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Perioperative red blood cell transfusion requirement for various surgical procedures in dogs: 207 cases (2004–2013) Adrienne L. Haley, DVM; F. A. Mann, DVM, MS; John Middleton, DVM, PhD; Courtney A. Nelson Objective—To compare perioperative RBC transfusion among dogs undergoing liver lobectomy, splenectomy, partial gastrectomy, rhinotomy, thyroidectomy, perineal herniorrhaphy, and intrathoracic surgery. Design—Retrospective case series. Animals—207 client-owned dogs that underwent various surgeries. Procedures—Medical records were reviewed for dogs that had undergone liver lobectomy, splenectomy, partial gastrectomy, rhinotomy, neoplastic thyroidectomy, perineal herniorrhaphy, or intrathoracic surgery. Transfusion requirement (packed RBC, whole blood, and bovine hemoglobin-based oxygen carrier) and survival rate at 2 weeks after surgery were compared among dogs undergoing the various surgeries. Results—Patients undergoing splenectomy and liver lobectomy were significantly more likely to receive RBC transfusion when each was compared with patients undergoing all other procedures. A significant association was found between body weight and perioperative RBC transfusion, with greater odds of transfusion as body weight increased. Dogs receiving perioperative RBC transfusions were significantly less likely to survive to 2 weeks after surgery. Conclusions and Clinical Relevance—Results indicated that dogs undergoing splenectomy and liver lobectomy may require RBC transfusion perioperatively. Veterinarians who perform these procedures should plan accordingly and have packed RBCs or whole blood donors readily available. (J Am Vet Med Assoc 2015;247:85–91)
A
s challenging major surgeries are increasingly performed by veterinarians, the necessity for perioperative RBC transfusions can be expected.1 Whole blood or packed RBC transfusions are used to meet this need.1 Hemorrhage in surgical patients immediately prior to, during, and after surgery is usually related to surgery, trauma, or neoplasia.2,3 Factors that may influence the decision to perform a RBC transfusion in a surgical patient include PCV, estimated volume of blood loss, and clinical signs indicative of inadequate oxygen delivery.2–6 On the basis of the clinical impression of the authors, patients undergoing certain surgical procedures may be more likely than others to hemorrhage severely enough to require RBC transfusion. Within the abdominal cavity, surgeries particularly associated with a risk for hemorrhage include partial gastrectomy, liver lobectomy, and splenectomy.4,7–9 Intrathoracic surgeries, including congenital vascular abnormality revisions, pulmonary mass excisions, and heart base mass excisions, are also associated with a risk for life-threatening hemorrhage.10–13 Additionally, extra-abdominal or extrathoracic surgeries known for increased risk of hemorrhage include neoplastic thyroidectomy, rhinotomy, and perineal herniorrhaphy.14–17 To the authors’ knowledge, no studies have examined From the Veterinary Medical Teaching Hospital, College of Veterinary Medicine, University of Missouri, Columbia, MO 65211. The authors have no sources of funding, financial conflicts of interest, or disclaimers to declare. Address correspondence to Dr. Haley ([email protected]). JAVMA, Vol 247, No. 1, July 1, 2015
the frequency with which RBC transfusions are required in relation to specific surgical procedures. The purpose of the study reported here was to compare the rate of transfusion among dogs undergoing specifically selected surgeries. We hypothesized that that there would be no difference in transfusion rate among partial gastrectomy, liver lobectomy, splenectomy, neoplastic thyroidectomy, rhinotomy, perineal herniorrhaphy, and intrathoracic surgery (ie, thoracotomy or median sternotomy). Materials and Methods Study population—The electronic medical record database at the University of Missouri Veterinary Medical Teaching Hospital was reviewed for canine patients having undergone liver lobectomy, splenectomy, thoracotomy, median sternotomy, neoplastic thyroidectomy, rhinotomy, perineal herniorrhaphy, partial gastrectomy, or exploratory celiotomy or celiotomy for treatment of gastric dilatation and volvulus, gastric neoplasia, adenocarcinoma, leiomyoma, or leiomyosarcoma between December 6, 2004, and May 1, 2013. Medical records for all patients that underwent liver lobectomy, splenectomy, thoracotomy, median sternotomy, neoplastic thyroidectomy, rhinotomy, perineal herniorrhaphy, or partial gastrectomy were further reviewed for inclusion in the study. Dogs that underwent more than 1 surgical procedure during the same surgical event or on separate occasions in the study period were excluded from the study, with the exception of patients undergoing splenectomy and liver lobectomy and those undergoing splenectomy Scientific Reports
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and gastrectomy. A complete surgical report and medical record were required for inclusion in the study. Criteria for RBC transfusion applied post hoc to the patients having undergone RBC transfusion included a PCV ≤ 24%, hypotension despite aggressive fluid therapy with a PCV < 30%, acute hemorrhage with > 20% estimated total blood volume loss or clinical signs consistent with anemia including tachycardia, tachypnea, bounding pulses, ventricular tachycardia, altered mentation, pale mucous membranes, and prolonged capillary refill time. Patients were excluded from the study if they received packed RBCs, whole blood, or bovine hemoglobin-based oxygen carriera transfusions and had incomplete records in terms of the reason for administering transfusion or did not meet all transfusion criteria. The study population was grouped on the basis of the surgical procedure performed: splenectomy, liver lobectomy, liver lobectomy and splenectomy, partial gastrectomy, partial gastrectomy and splenectomy, perineal herniorrhaphy, rhinotomy, neoplastic thyroidectomy, and intrathoracic procedures. The intrathoracic-procedures group included patients undergoing median sternotomy and thoracotomy; however, intrathoracic surgeries were not categorized further by specific procedure because of large variations in the underlying surgical diseases and procedures performed limiting the population sizes. Data collection—From the medical records, the variables recorded for the study were patient signalment; patient body weight; type of surgery performed; perioperative whole blood, packed RBCs, or bovine hemoglobin-based oxygen carriera transfusion requirement (yes or no); preoperative PCV; pretransfusion PCV when applicable; and patient survival status (yes or no). For the purposes of this study, the perioperative period was considered to include the preoperative, intraoperative, and postoperative periods. The preoperative period included the time from arrival at the hospital on the day of surgery to induction of anesthesia. The intraoperative period was considered to include the period from induction of anesthesia to surgical closure. The postoperative period was considered to include up to 24 hours after surgery. Patient survival rate was defined by dogs that survived to 2 weeks after surgery. Statistical analyses—For the purposes of data analysis, a series of categorical variables were created on the basis of prevalence within the studied population, with the most prevalent group serving as the referent population. Surgical procedure type was coded on the basis of descending prevalence as splenectomy, liver lobectomy, liver lobectomy and splenectomy, partial gastrectomy, partial gastrectomy and splenectomy, perineal hernia, rhinotomy, thyroidectomy, and intrathoracic procedures. A similar numeric assignment for dog breed was followed. For dog breed, any breeds represented by < 3 individuals were grouped together in a single category as miscellaneous other breeds. Perioperative transfusion and surviving to 2 weeks after surgery were categorically assigned. Patient age and weight were included in the analyses as continuous variables. Mean age and body weight were compared among surgical procedure type categories by means of 1-way ANOVA with post hoc Tukey-Kramer multiple compar86
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ison tests. Age and body weight met the assumptions of normality and equality of variances. Proportional data were compared between groups by means of the χ2 test or Fisher exact test, as appropriate. Multivariable logistic regression was performed to determine the relationship between transfusion as the dependent variable and surgery type, sex, breed, survival rate at 2 weeks after surgery, age, and body weight as the independent variables. Survival rate at 2 weeks after surgery was similarly analyzed with the replacement of survival rate at 2 weeks after surgery with transfusion as an independent variable and survival rate at 2 weeks after surgery as the dependent variable. Post hoc analysis was performed with dummy variables to compare each surgical type against all other procedures with multiple logistic regression where the dependent variable was the need for transfusion; the independent variables were surgery type, survival rate at 2 weeks after surgery, and body weight (other variables such as age, sex, and breed were excluded because they were previously found to be not significant). Survival rate at 2 weeks after surgery was similarly analyzed with the replacement of survival rate at 2 weeks after surgery with transfusion as an independent variable and survival rate at 2 weeks after surgery as the dependent variable. Values of P < 0.05 were considered significant. Statistical analysis was performed with the aid of statistical software.b,c Results Signalment—During the study period, 218 dogs underwent liver lobectomy, splenectomy, thoracotomy, median sternotomy, neoplastic thyroidectomy, rhinotomy, perineal herniorrhaphy or partial gastrectomy procedures. Excluded from the study were 2 dogs with incomplete transfusion records, 3 dogs that failed to meet the criteria for undergoing blood transfusion as already described, 4 dogs that underwent multiple surgical procedures on different occasions during the study period, 1 dog that had an incomplete medical record, and 1 dog that was misclassified as undergoing a splenectomy in the medical record. The final study included 207 dogs. The median age of dogs included in the study was 9 years (range, 0.5 to 17 years). Included in the study were 6 (2.9%) sexually intact females, 78 (37.7%) spayed females, 39 (18.8%) sexually intact males, and 84 (40.6%) castrated males. Sixty-two dog breeds were included in the study, including mixed breed (n = 47 [22.7%]), Labrador Retriever (32 [15.5%]), Golden Retriever (12 [5.8%]), German Shepherd Dog (11 [5.3%]), Beagle (7 [3.4%]), Border Collie (7 [3.4%]), Boxer (7 [3.4%]), Shetland Sheepdog (5 [2.4%]), American Staffordshire Terrier (3 [1.4%]), English Bulldog (3 [1.4%]), Dachshund (3 [1.4%]), Great Dane (3 [1.4%]), Shih Tzu (3 [1.4%]), and Yorkshire Terrier (3 [1.4%]). The remaining breeds were grouped as miscellaneous breeds (n = 61 [29.5%]). The median body weight of dogs included in the study was 26.7 kg (58.7 lb; range, 3.1 to 58.4 kg [6.8 to 128.5 lb]). Analysis by use of the Tukey-Kramer multiple comparison test revealed that mean body weight differed significantly among surgical types (Table 1). Multiple logistic regression analysis revealed that there was no association between age, sex, or breed and the need for transfusion JAVMA, Vol 247, No. 1, July 1, 2015
Table 1—Descriptive statistics by surgery type in 207 dogs. No. (%) that received a transfusion
Mean ± SEM age (y)
Mean ± SEM weight (kg)
27 (41.5) 6 (40.0) 4 (28.6) 4 (36.4) 2 (28.5)
9.6 ± 0.4a 9.5 ± 0.8 10.2 ± 0.8 8.1 ± 0.9 8.6 ± 1.2
27.9 ± 1.5 23.3 ± 3.2 27.8 ± 3.3 33.3 ± 3.7b 35.9 ± 4.7c
1 (4.5) 0 (0.0) 0 (0.0) 4 (9.3)
8.8 ± 0.7 7.4 ± 0.8 9.6 ± 0.8 7.5 ± 0.5a
18.6 ± 2.6b,c 25.1 ± 3.1 25.9 ± 3.3 23.2 ± 1.9
Splenectomy (n = 65) Liver lobectomy (n = 15) Liver lobectomy and splenectomy (n = 14) Partial gastrectomy (n = 11) Partial gastrectomy and splenectomy (n = 7) Perineal hernia repair (n = 22) Rhinotomy (n = 16) Neoplastic thyroidectomy (n = 14) Intrathoracic procedures (n = 43)
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Surgical procedure
a Mean age differed significantly (P = 0.015) between splenectomy and intrathoracic surgery groups. Mean weight differed significantly (P = 0.009) between partial gastrectomy and perineal herniorrhaphy groups. cMean weight differed significantly (P = 0.009) between partial gastrectomy and splenectomy and perineal herniorrhaphy groups. b
Table 2—Results of multivariable logistic regression evaluating the association between the need for a transfusion and surgical procedure, survival rate, sex, breed, age, and body weight for 207 dogs. Variable Surgical procedure Survival rate* Sex Breed Age (0.5–17 y) Weight (3.1–58.4 kg)
Coefficient
OR
5% lower confidence limit
95% upper confidence limit
P value
–0.41 –2.43 0.23 –0.0006 0.07 0.04
0.66 0.09 1.3 1.0 1.07 1.04
0.55 0.03 0.75 0.93 0.93 1.01
0.79 0.25 2.11 1.07 1.23 1.07
< 0.001 < 0.001 0.383 0.986 0.343 0.024
*Surviving to 2 weeks after surgery.
(Table 2). However, there was a significant association between the need for perioperative RBC transfusion and surgery type, survival rate at 2 weeks after surgery, and body weight. The odds of transfusion increased with body weight (OR, 1.039; P = 0.024). Surgical type—During the study period, there were 65 splenectomies, 15 liver lobectomies, 11 partial gastrectomies, 14 liver lobectomy and splenectomies, 7 partial gastrectomy and splenectomies, 14 neoplastic thyroidectomies, 16 rhinotomies, 22 perineal herniorrhaphies, and 43 intrathoracic procedures performed. Intrathoracic procedures performed included lung lobectomy (20), esophagotomy (4), exploratory for pyothorax (4), thoracic duct ligation and pericardectomy (4), mediastinal mass excision (2), mediastinal biopsy (2), thoracic wall excision (2), heart base mass excision (1), lymph node biopsy (1), lung biopsy (1), pericardectomy (1), and vascular ring anomaly repair (1). Transfusion—Of the 207 dogs included in the study, 48 (23.2%) required perioperative packed RBCs, whole blood, or bovine hemoglobin-based oxygen carriera transfusion. No cell-salvage procedures were performed in any dogs. The timing of transfusion was determined for dogs that received blood transfusions in each surgical category (Table 3). No significant differences were found in the proportions of dogs receiving transfusions during each time frame. The number of dogs that received blood transfusions in each surgical category was determined (Table 4). Patients within the intrathoracic group that received RBC transfusions included those undergoing thoracic duct ligation (n = JAVMA, Vol 247, No. 1, July 1, 2015
2), pyothorax exploratory (1), and mediastinal mass excision (1). No significant (P = 0.129) differences were found in the proportions of dogs that had a transfusion between the different intrathoracic procedures. A significant association was identified between RBC transfusion and surgical type. Compared with splenectomy, all other procedures had significantly (P < 0.001) lower odds of transfusion (OR, 0.159). Likewise, compared with liver lobectomy, all other procedures had significantly (P = 0.042) lower odds of transfusion (OR, 0.299). Conversely, compared with intrathoracic procedures, all other procedures had significantly (P = 0.007) greater odds of transfusion (OR, 5.524). Survival rate analysis—Of 207 total dogs in the study population, 173 (83.6%) survived. Of the 34 total dogs that did not survive to 2 weeks after surgery, 27 (79.4%) were euthanized, with the most common reason for euthanasia being poor prognosis resulting from continued decline in condition despite all efforts to stabilize the patient. The total number of dogs that survived in each surgical category was determined (Table 4). For those patients not requiring transfusion (159), 144 (90.6%) survived. Of the 48 total dogs in the study population that received perioperative RBC transfusions, 29 (60.4%) survived. The number of dogs that received blood transfusions and survived in each surgical category was determined (Table 4). As there were no significant (P ≥ 0.055) differences in the survival rate between procedure types in the intrathoracic category regardless of transfusion, the intrathoracic procedures were not categorized further for logistic regression. No significant (P ≥ 0.349) association was found between survival rate at 2 Scientific Reports
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Table 3—Number of 48 dogs receiving an RBC transfusion, organized according to procedure and timing of transfusion. Timing of RBC transfusion relative to surgery Procedure
Before
During
After
Before and during
4 0 0 1 0 0 0
8 0 1 1 1 0 0
7 1 2 2 1 1 3
2 0 0 0 0 0 0
Splenectomy Liver lobectomy Liver lobectomy and splenectomy Gastrectomy Gastrectomy and splenectomy Perineal hernia Thoracotomy
Before and During and after after 4 0 0 0 0 0 0
Before, during, and after
Total
P value
0 1 0 0 0 0 0
27 6 4 4 2 1 4
0.136 0.105 0.687 0.687 1.000 NA 0.486
2 4 1 0 0 0 1
Columns listing more than 1 period represent multiple single transfusions, each administered during a separate period of time. P values represent the outcome of a Fisher exact test performed on within-row data. The denominator for the Fisher exact test in each cell was the row total minus the cell value. Procedures with no patients receiving transfusions were excluded from the table. NA = Not applicable.
Table 4—Transfusion and 2-week survival rate data for each surgical procedure in 207 dogs. Transfusion*
Transfusion and survived†
No transfusion*
No transfusion and survived†
Total survivors*
Splenectomy (n = 65) Liver lobectomy (n = 15) Liver lobectomy and splenectomy (n = 14) Partial gastrectomy (n = 11) Gastrectomy and splenectomy (n = 7)
27 (42) 6 (40) 4 (29) 4 (36) 2 (29)
20 (74) 5 (83) 2 (50) 1 (25) 0 (0)
38 (58) 9 (60) 10 (71) 7 (64) 5 (71)
37 (97) 8 (89) 8 (80) 5 (71) 4 (80)
57 (88) 13 (87) 10 (71) 6 (55) 4 (57)
Neoplastic thyroidectomy (n = 14) Rhinotomy (n = 16) Perineal herniorrhaphy (n = 22) Intrathoracic procedures (n = 43) Total (n = 207)
0 (0) 0 (0) 1 (5) 4 (9) 48 (23)
NA NA 0 (0) 1 (25) 29 (60)
14 (100) 16 (100) 21 (95) 39 (91) 159 (77)
14 (100) 16 (100) 20 (95) 32 (82) 144 (91)
14 (100) 16 (100) 20 (91) 33 (77) 173 (84)
Surgical procedure
Values are number (%). *Denominator is within-row total number of dogs. †Denominator is number of dogs that received a transfusion or number of dogs that did not, as applicable. NA = Not applicable.
Table 5—Results of multivariable logistic regression evaluating the association between patient 2-week survival rate and surgery type, transfusion, sex, breed, age, and body weight in 207 dogs. Variable Surgical procedure Transfusion Sex Breed Age (0.5–17 y) Weight (3.1–58.4 kg)
Coefficient
OR
5% lower confidence limit
95% upper confidence limit
P value
–0.19 –2.45 0.08 –0.003 –0.06 –0.12
0.82 0.09 1.08 1.00 1.06 0.99
0.70 0.03 0.68 0.93 0.94 0.96
0.97 0.25 1.72 1.07 1.21 1.02
0.020 < 0.001 0.743 0.937 0.349 0.474
weeks after surgery and sex, breed, age, and body weight (Table 5). However, there was a negative association between survival rate and transfusion, with dogs that had a transfusion having lower odds of surviving to 2 weeks after surgery than those that did not have a transfusion (OR, 0.087; P < 0.001). Similarly, there was a negative association between survival rate at 2 weeks after surgery and surgery type, irrespective of RBC transfusion (OR, 0.824; P = 0.020). Compared with splenectomy, all other procedures had lower odds of the dogs’ surviving to 2 weeks after surgery (OR, 0.246; P = 0.008). Conversely, compared with partial gastrectomy, all other procedures had higher odds of the dogs’ surviving to 2 weeks after surgery (OR, 4.602; P = 0.029). Similarly, compared with thoracotomy, all other procedures had higher odds of the 88
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dogs’ surviving to 2 weeks after surgery (OR, 3.392; P = 0.014). Discussion Limited information has been published on the rate of perioperative RBC transfusion in dogs undergoing splenectomy, liver lobectomy, partial gastrectomy, thyroidectomy, rhinotomy, perineal herniorrhaphy, or intrathoracic procedures. Current resources indicate that there is increased risk of hemorrhage when performing these surgical procedures; however, to the authors’ knowledge, the number of patients undergoing these procedures that receive RBC transfusion has never been quantified.8–11,14–17 JAVMA, Vol 247, No. 1, July 1, 2015
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risk for severe hemorrhage.12,13 If our study population contained a greater number of dogs that underwent cardiovascular procedures, intrathoracic procedures could have been analyzed in subcategories rather than as a single group. Body weight was another variable found to be significantly related to increased odds of perioperative RBC transfusion. Although the only significant differences in mean body weight were found between patients undergoing partial gastrectomy and partial gastrectomy and splenectomy and those undergoing perineal herniorrhaphy, the lack of significant differences in mean body weight among all surgical types may reflect sample size and within-category variation. Many of the surgical procedures considered in this study are performed more often in medium- to large-breed dogs; therefore, it seems likely that the type of surgery performed would be associated with body weight, but this assertion was not confirmed in the present study. Large- and giantbreed dogs are often deep chested, making observation of organs in the thorax and cranial portion of the abdomen more difficult. In addition, some dogs in the study population could be considered overweight or obese. Obesity is an accepted risk factor for increased surgical difficulty because excess adipose tissue may impede the surgeon’s ability to view the surgical site and may also contribute to the slippage of ligatures.20,21 In this study, 61.2% of all dogs that underwent perioperative RBC transfusions survived. This result is similar to the results in a study by Callan et al,22 in which 61% of 307 dogs that received RBC transfusions survived to hospital discharge. In another study by Godinho-Cunha et al,23 15 dogs and cats received 19 RBC transfusions, and 60% survived to discharge from the hospital. In a study by Kerl and Hohenhaus,5 only 47% of 131 dogs receiving RBC transfusions survived to hospital discharge. Because these studies were specifically designed to examine patients receiving RBC transfusions, these investigators were unable to examine the survival rate in patients receiving RBC transfusion versus a control population that did not have a transfusion.5,22,23 They also examined a broader population of patients requiring blood transfusion, including those with nonsurgical hemorrhage, hemolysis, and ineffective erythropoiesis.5,22,23 In the present study, survival rate at 2 weeks after surgery was inversely related to perioperative blood transfusion, meaning that those dogs undergoing perioperative RBC transfusion had a decreased chance of surviving to 2 weeks after surgery. Because of the retrospective nature of this study and the variability of information consistently included in all patient medical records, multiple factors that likely affected postoperative survival rate were not included in statistical analysis, including underlying disease processes, concurrent illnesses, and patient physical status on the veterinary modification of the American Society of Anesthesiologists scale.24 Because these data were not consistently available and thus not included in statistical analysis, it is unclear what role RBC transfusion alone plays in the survival rate of surgical patients after surgery. It is likely that patients requiring preoperative RBC transfusion would have been classified as having a higher physical status on the veterinary modification of Scientific Reports
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Dogs undergoing splenectomy and those undergoing liver lobectomy had greater odds of receiving perioperative RBC transfusions than those undergoing the remaining surgical procedures. One possible explanation for this finding is that the most common reason for surgical removal of these organs is neoplasia. Organ removal as a result of neoplasia may be complicated because of increased blood supply to the tumors and sometimes decreased ability to view important structures as a result of tumor size.9 In addition, some tumors, especially hemangiosarcoma, a common splenic tumor, can often be friable and bleed easily when handled.18 Patients with splenic and liver tumors may even require preoperative or intraoperative RBC transfusion prior to surgical manipulation of the organs in cases of hemorrhagic peritoneal effusion.4,8 At the authors’ hospital (University of Missouri Veterinary Teaching Hospital), partial gastrectomy is most commonly performed to remove gastric tissue damaged secondary to gastric dilation and volvulus. It has been reported that during gastric dilation and volvulus, both mucosal and serosal hemorrhage occur.19 Meticulous surgical technique can prevent excessive hemorrhage during thyroidectomy, rhinotomy, perineal herniorrhaphy, and intrathoracic surgery.10,11,15,17 Patients undergoing these procedures are not often actively hemorrhaging at the time of surgery and generally do not require preoperative RBC transfusion. Although there is risk of hemorrhage in dogs undergoing these procedures,14–17 there were no significantly increased odds of RBC transfusion in the present study for these dogs, compared with those undergoing splenectomy or liver lobectomy. For the purposes of the present study, patients were included if they received one or multiple RBC transfusions in the preoperative, intraoperative, or postoperative period, as already defined. No significant differences were identified in the proportions of dogs receiving RBC transfusions during each of these periods; therefore, the data were grouped together as 1 perioperative period. In the case of patients receiving RBC transfusions in the preoperative period, the need for transfusion cannot be attributed to the surgical procedure itself. However, many patients receiving RBC transfusions in the preoperative period require transfusions because of acute blood loss secondary to surgical diseases such as trauma or neoplasia. It was for this reason that the authors opted to include those patients in the study. In the present study, patients undergoing intrathoracic procedures were not further categorized on the basis of specific procedure type for statistical analysis. This was because preliminary statistical analysis comparing the need for transfusion and survival rate among intrathoracic procedures revealed that there were no significant differences among specific procedures within this category. The population of dogs that underwent intrathoracic procedures in the present study included most patients undergoing lung lobectomy, none of which received transfusions. In addition, only a single patient underwent heart base mass excision, with another undergoing vascular ring anomaly repair, procedures that would generally be considered at greater
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the American Society of Anesthesiologists scale perioperatively and therefore would have had multiple factors contributing to an overall decreased chance of surviving.24 Likewise, patients needing perioperative transfusion likely had more complicated disease processes impacting their prognosis. Despite growing concerns over the risks versus benefits of RBC transfusions in anemic patients, there continues to be a lack of definitive guidelines for when blood products should be administered. Kerl and Hohenhaus5 developed a transfusion need scale on the basis of current hospital transfusion practices and available human literature in 1989; this scale assigned point values to criteria including anemia determined by PCV, history of rapid blood loss versus gradual decrease in RBC production, need for anesthesia, and clinical signs related to anemia, such as weakness, tachypnea, and tachycardia. It was concluded that although the scale identified many patients that required blood transfusions, some patients were assigned inappropriately high scores (increased need for transfusion) on the basis of clinical appearance.5 Conversely, the scale failed in dogs with acute blood loss that would not yet have changes in their PCV or anesthetized patients that would not acquire points for clinical signs such as tachypnea or weakness.5 The published scale was therefore considered inappropriate for use in the present study. Patients in the present study were examined post hoc for appropriateness of blood transfusion on the basis of the most current recommendations from multiple resources and examination of available medical records.2–6 The transfusion criteria were compared with the medical records of those patients that had received RBC transfusions. If those patients met one or more of the criteria, it was deemed that the clinician had medically sound and documented reasons for administering an RBC transfusion. Patients that did not receive RBC transfusion were not compared with the transfusion criteria to determine whether they potentially should have received a transfusion, given that some clinical information pertinent to the transfusion inclusion criteria was recorded only for those patients that received RBC transfusions. Change in patient PCV and estimated blood loss were not included in analysis because of inconsistent recording and variations in the amount of fluids administered perioperatively, estimated blood loss, and postoperative and post-transfusion PCV. Limitations of the present study included the retrospective nature and the variation in sample size within surgical groups. Also, the surgeries included in this study are only a sample of intraabdominal, intrathoracic, and extraabdominal or extrathoracic surgeries performed by veterinary surgeons, and many procedures that could have been included were not examined. The surgeries included were chosen by the authors as a sample of procedures for inclusion on the basis of the clinical impression that they were likely to be equally at risk for excessive hemorrhage and perioperative RBC transfusion requirement; however, they do not represent all surgeries performed by veterinarians. This potentially may have unintentionally created a bias in the study results. An additional limitation is that although the authors can document that the dogs that 90
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underwent transfusion met the inclusion criteria, they cannot state with certainty that all the dogs that did not receive a transfusion did not need one. In addition, 79.4% of nonsurvivors were euthanized, with the most common reason for euthanasia being poor prognosis resulting from continued decline in condition despite all efforts to stabilize the patient. Although the decision to perform euthanasia was made to relieve signs of pending natural death in most cases, it may have introduced bias into the survival rate data, inasmuch as outcome was determined by owner decision rather than natural causes. As veterinarians take on the task of increasingly difficult surgeries, the use of perioperative RBC transfusion may increase. Given this fact, hospitals where these procedures are being performed need to be prepared to administer such blood products, by keeping packed RBCs in stock and having readily available whole blood donors. According to our findings, dogs undergoing splenectomy and liver lobectomy were at increased risk for requiring perioperative RBC transfusion, compared with those undergoing concurrent liver lobectomy and splenectomy, partial gastrectomy, concurrent partial gastrectomy and splenectomy, rhinotomy, neoplastic thyroidectomy, perineal herniorrhaphy, or thoracotomy or median sternotomy. Further prospective study is required to determine how RBC transfusion affects survival rate in postoperative patients. a. b. c.
Oxyglobin, OPK Biotech LLC, Cambridge, Mass. NCSS 2007, Number Cruncher Statistical Software, Kaysville, Utah. Sigmaplot, version 12.0, SigmaStat Statistical Software, San Rafael, Calif.
References 1.
Jutkowitz LA, Rozanski EA, Moreau JA, et al. Massive transfusion in dogs: 15 cases (1997–2001). J Am Vet Med Assoc 2002;220:1664–1669. 2. Ari Jutkowitz L. Blood transfusion in the perioperative period. Clin Tech Small Anim Pract 2004;19:75–82. 3. Giacomo S, Otto CM. Shock. In: Tobias KM, Johnston SA, eds. Veterinary surgery: small animal. Philadelphia: Saunders Elsevier, 2012;73–93. 4. Herold LV, Devey JJ, Kirby R, et al. Clinical evaluation and management of hemoperitoneum in dogs. J Vet Emerg Crit Care 2008;18:40–53. 5. Kerl ME, Hohenhaus AE. Packed red blood cell transfusions in dogs: 131 cases (1989). J Am Vet Med Assoc 1993;202:1495– 1499. 6. Silverstein D, Campbell J. Fluid therapy. In: Tobias KM, Johnston SA, eds. Veterinary surgery: small animal. Philadelphia: Saunders Elsevier, 2012;43–72. 7. Risselada M, Ellison GW, Bacon NJ, et al. Comparison of 5 surgical techniques for partial liver lobectomy in the dog for intraoperative blood loss and surgical time. Vet Surg 2010;39:856– 862. 8. Marino DJ, Matthiesen DT, Fox PR, et al. Ventricular arrhythmias in dogs undergoing splenectomy: a prospective study. Vet Surg 1994;23:101–106. 9. Monarski CJ, Jaffe MH, Kass PH. Decreased surgical time with a vessel sealing device versus a surgical stapler in performance of canine splenectomy. J Am Anim Hosp Assoc 2014;50:42–45. 10. Burton CA, White RN. Review of the technique and complications of median sternotomy in the dog and cat. J Small Anim Pract 1996;37:516–522. 11. Radlinsky MG. Thoracic cavity. In: Tobias KM, Johnston SA, JAVMA, Vol 247, No. 1, July 1, 2015
13. 14. 15. 16. 17. 18.
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1: epidemiologic, clinical characteristics as well as histopathologic diagnosis in 249 cases (2000–2011). Tierarztl Prax Ausg K Kleintiere Heimtiere 2012;40:250–260. Volk SW. Gastric dilatation-volvulus and bloat. In: Silverstein DC, Hopper K, eds. Small animal critical care medicine. St Louis: Saunders Elsevier, 2009;584–588. Van Goethem BE, Rosenveldt KW, Kirpenstein J. Monopolar versus bipolar electrocoagulation in canine laparoscopic ovariectomy: a nonrandomized, prospective, clinical trial. Vet Surg 2003;32:464–470. Chan DL. Metabolism and nutritional needs of surgical patients. In: Tobias KM, Johnston SA, eds. Veterinary surgery: small animal. Philadelphia: Saunders Elsevier, 2012;121–124. Callan MB, Oakley DA, Shofer FS, et al. Canine red blood cell transfusion practice. J Am Anim Hosp Assoc 1996;32:303–311. Godinho-Cunha LF, Ferreira RM, Silvestre-Ferreira AC. Whole blood transfusion in small animals: indications and effects. An Acad Bras Cienc 2011;83:611–617. Swanson EA, Mann FA. Preoperative patient assessment. In: Mann FA, Constantinescu GM, Yoon HY, eds. Fundamentals of small animal surgery. Ames, Iowa: Wiley-Blackwell, 2011;3–7.
From this month’s AJVR
Cardiovascular effects of equipotent doses of isoflurane alone and isoflurane plus fentanyl in New Zealand White rabbits (Oryctolagus cuniculus) Caitlin C. Tearney et al Objective—To determine effects of equipotent concentrations of fentanyl and isoflurane, compared with isoflurane alone, on cardiovascular variables in New Zealand White rabbits (Oryctolagus cuniculus). Animals—6 adult female New Zealand White rabbits. Procedures—Rabbits were anesthetized with isoflurane, and lungs were mechanically ventilated. The minimum alveolar concentration (MAC) of isoflurane alone (baseline) and with fentanyl administered IV to achieve 3 targeted plasma concentrations was determined for each rabbit by means of an electrical stimulus. Cardiovascular variables were measured in a separate experiment at 1.3X the isoflurane MAC and equipotent doses of isoflurane plus fentanyl at the same 3 targeted plasma concentrations. Blood samples were collected for measurement of blood gas variables and plasma fentanyl concentrations. Treatment effects were evaluated by repeated-measures ANOVA followed by 2-tailed paired t tests with sequentially rejective Bonferroni correction. Results—Mean ± SD MAC of isoflurane was 1.95 ± 0.27%. Mean measured plasma fentanyl concentrations of 4.97, 8.93, and 17.19 ng/mL reduced isoflurane MAC by 17%, 37%, and 56%, respectively. Mean measured plasma fentanyl concentrations during cardiovascular measurements were 5.49, 10.26, and 18.40 ng/mL. Compared with baseline measurements, heart rate was significantly lower at all 3 plasma fentanyl concentrations, mean arterial blood pressure and systemic vascular resistance were significantly higher at mean fentanyl concentrations of 10.26 and 18.40 ng/mL, and cardiac output was significantly higher at 18.40 ng of fentanyl/mL. Conclusions and Clinical Relevance—Administration of fentanyl in isoflurane-anesthetized rabbits resulted in improved mean arterial blood pressure and cardiac output, compared with isoflurane alone. This balanced anesthesia technique may prove useful in the management of clinical cases in this species. (Am J Vet Res 2015;76:591–598)
JAVMA, Vol 247, No. 1, July 1, 2015
July 2015
See the midmonth issues of JAVMA for the expanded table of contents for the AJVR or log on to avmajournals.avma.org for access to all the abstracts.
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12.
eds. Veterinary surgery: small animal. Philadelphia: Saunders Elsevier, 2012;1787–1812. Hunt GB, Simpson DJ, Beck JA, et al. Intraoperative hemorrhage during patent ductus arteriosus ligation in dogs. Vet Surg 2001;30:58–63. Morges M, Worley DR, Withrow SJ, et al. Pericardial free patch grafting as a rescue technique in surgical management of right atrial HSA. J Am Anim Hosp Assoc 2011;47:224–228. Slensky KA, Volk SW, Schwarz T, et al. Acute severe hemorrhage secondary to arterial invasion in a dog with thyroid carcinoma. J Am Vet Med Assoc 2003;223:649–653. Radlinsky MG. Thyroid surgery in dogs and cats. Vet Clin North Am Small Anim Pract 2007;37:789–798. Aronson LR. Rectum, anus, and perineum. In: Tobias KM, Johnston SA, eds. Veterinary surgery: small animal. Philadelphia: Saunders Elsevier, 2012;1564–1600. Hedlund CS, Tangner CH, Elkins AD, et al. Temporary bilateral carotid artery occlusion during surgical exploration of the nasal cavity of the dog. Vet Surg 1983;12:83–85. Eberle N, von Babo V, Nolte I, et al. Splenic masses in dogs. Part
Perioperative red blood cell transfusion requirement for various surgical procedures in dogs: 207 cases (2004–2013) Adrienne L. Haley, DVM; F. A. Mann, DVM, MS; John Middleton, DVM, PhD; Courtney A. Nelson Objective—To compare perioperative RBC transfusion among dogs undergoing liver lobectomy, splenectomy, partial gastrectomy, rhinotomy, thyroidectomy, perineal herniorrhaphy, and intrathoracic surgery. Design—Retrospective case series. Animals—207 client-owned dogs that underwent various surgeries. Procedures—Medical records were reviewed for dogs that had undergone liver lobectomy, splenectomy, partial gastrectomy, rhinotomy, neoplastic thyroidectomy, perineal herniorrhaphy, or intrathoracic surgery. Transfusion requirement (packed RBC, whole blood, and bovine hemoglobin-based oxygen carrier) and survival rate at 2 weeks after surgery were compared among dogs undergoing the various surgeries. Results—Patients undergoing splenectomy and liver lobectomy were significantly more likely to receive RBC transfusion when each was compared with patients undergoing all other procedures. A significant association was found between body weight and perioperative RBC transfusion, with greater odds of transfusion as body weight increased. Dogs receiving perioperative RBC transfusions were significantly less likely to survive to 2 weeks after surgery. Conclusions and Clinical Relevance—Results indicated that dogs undergoing splenectomy and liver lobectomy may require RBC transfusion perioperatively. Veterinarians who perform these procedures should plan accordingly and have packed RBCs or whole blood donors readily available. (J Am Vet Med Assoc 2015;247:85–91)
A
s challenging major surgeries are increasingly performed by veterinarians, the necessity for perioperative RBC transfusions can be expected.1 Whole blood or packed RBC transfusions are used to meet this need.1 Hemorrhage in surgical patients immediately prior to, during, and after surgery is usually related to surgery, trauma, or neoplasia.2,3 Factors that may influence the decision to perform a RBC transfusion in a surgical patient include PCV, estimated volume of blood loss, and clinical signs indicative of inadequate oxygen delivery.2–6 On the basis of the clinical impression of the authors, patients undergoing certain surgical procedures may be more likely than others to hemorrhage severely enough to require RBC transfusion. Within the abdominal cavity, surgeries particularly associated with a risk for hemorrhage include partial gastrectomy, liver lobectomy, and splenectomy.4,7–9 Intrathoracic surgeries, including congenital vascular abnormality revisions, pulmonary mass excisions, and heart base mass excisions, are also associated with a risk for life-threatening hemorrhage.10–13 Additionally, extra-abdominal or extrathoracic surgeries known for increased risk of hemorrhage include neoplastic thyroidectomy, rhinotomy, and perineal herniorrhaphy.14–17 To the authors’ knowledge, no studies have examined From the Veterinary Medical Teaching Hospital, College of Veterinary Medicine, University of Missouri, Columbia, MO 65211. The authors have no sources of funding, financial conflicts of interest, or disclaimers to declare. Address correspondence to Dr. Haley ([email protected]). JAVMA, Vol 247, No. 1, July 1, 2015
the frequency with which RBC transfusions are required in relation to specific surgical procedures. The purpose of the study reported here was to compare the rate of transfusion among dogs undergoing specifically selected surgeries. We hypothesized that that there would be no difference in transfusion rate among partial gastrectomy, liver lobectomy, splenectomy, neoplastic thyroidectomy, rhinotomy, perineal herniorrhaphy, and intrathoracic surgery (ie, thoracotomy or median sternotomy). Materials and Methods Study population—The electronic medical record database at the University of Missouri Veterinary Medical Teaching Hospital was reviewed for canine patients having undergone liver lobectomy, splenectomy, thoracotomy, median sternotomy, neoplastic thyroidectomy, rhinotomy, perineal herniorrhaphy, partial gastrectomy, or exploratory celiotomy or celiotomy for treatment of gastric dilatation and volvulus, gastric neoplasia, adenocarcinoma, leiomyoma, or leiomyosarcoma between December 6, 2004, and May 1, 2013. Medical records for all patients that underwent liver lobectomy, splenectomy, thoracotomy, median sternotomy, neoplastic thyroidectomy, rhinotomy, perineal herniorrhaphy, or partial gastrectomy were further reviewed for inclusion in the study. Dogs that underwent more than 1 surgical procedure during the same surgical event or on separate occasions in the study period were excluded from the study, with the exception of patients undergoing splenectomy and liver lobectomy and those undergoing splenectomy Scientific Reports
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and gastrectomy. A complete surgical report and medical record were required for inclusion in the study. Criteria for RBC transfusion applied post hoc to the patients having undergone RBC transfusion included a PCV ≤ 24%, hypotension despite aggressive fluid therapy with a PCV < 30%, acute hemorrhage with > 20% estimated total blood volume loss or clinical signs consistent with anemia including tachycardia, tachypnea, bounding pulses, ventricular tachycardia, altered mentation, pale mucous membranes, and prolonged capillary refill time. Patients were excluded from the study if they received packed RBCs, whole blood, or bovine hemoglobin-based oxygen carriera transfusions and had incomplete records in terms of the reason for administering transfusion or did not meet all transfusion criteria. The study population was grouped on the basis of the surgical procedure performed: splenectomy, liver lobectomy, liver lobectomy and splenectomy, partial gastrectomy, partial gastrectomy and splenectomy, perineal herniorrhaphy, rhinotomy, neoplastic thyroidectomy, and intrathoracic procedures. The intrathoracic-procedures group included patients undergoing median sternotomy and thoracotomy; however, intrathoracic surgeries were not categorized further by specific procedure because of large variations in the underlying surgical diseases and procedures performed limiting the population sizes. Data collection—From the medical records, the variables recorded for the study were patient signalment; patient body weight; type of surgery performed; perioperative whole blood, packed RBCs, or bovine hemoglobin-based oxygen carriera transfusion requirement (yes or no); preoperative PCV; pretransfusion PCV when applicable; and patient survival status (yes or no). For the purposes of this study, the perioperative period was considered to include the preoperative, intraoperative, and postoperative periods. The preoperative period included the time from arrival at the hospital on the day of surgery to induction of anesthesia. The intraoperative period was considered to include the period from induction of anesthesia to surgical closure. The postoperative period was considered to include up to 24 hours after surgery. Patient survival rate was defined by dogs that survived to 2 weeks after surgery. Statistical analyses—For the purposes of data analysis, a series of categorical variables were created on the basis of prevalence within the studied population, with the most prevalent group serving as the referent population. Surgical procedure type was coded on the basis of descending prevalence as splenectomy, liver lobectomy, liver lobectomy and splenectomy, partial gastrectomy, partial gastrectomy and splenectomy, perineal hernia, rhinotomy, thyroidectomy, and intrathoracic procedures. A similar numeric assignment for dog breed was followed. For dog breed, any breeds represented by < 3 individuals were grouped together in a single category as miscellaneous other breeds. Perioperative transfusion and surviving to 2 weeks after surgery were categorically assigned. Patient age and weight were included in the analyses as continuous variables. Mean age and body weight were compared among surgical procedure type categories by means of 1-way ANOVA with post hoc Tukey-Kramer multiple compar86
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ison tests. Age and body weight met the assumptions of normality and equality of variances. Proportional data were compared between groups by means of the χ2 test or Fisher exact test, as appropriate. Multivariable logistic regression was performed to determine the relationship between transfusion as the dependent variable and surgery type, sex, breed, survival rate at 2 weeks after surgery, age, and body weight as the independent variables. Survival rate at 2 weeks after surgery was similarly analyzed with the replacement of survival rate at 2 weeks after surgery with transfusion as an independent variable and survival rate at 2 weeks after surgery as the dependent variable. Post hoc analysis was performed with dummy variables to compare each surgical type against all other procedures with multiple logistic regression where the dependent variable was the need for transfusion; the independent variables were surgery type, survival rate at 2 weeks after surgery, and body weight (other variables such as age, sex, and breed were excluded because they were previously found to be not significant). Survival rate at 2 weeks after surgery was similarly analyzed with the replacement of survival rate at 2 weeks after surgery with transfusion as an independent variable and survival rate at 2 weeks after surgery as the dependent variable. Values of P < 0.05 were considered significant. Statistical analysis was performed with the aid of statistical software.b,c Results Signalment—During the study period, 218 dogs underwent liver lobectomy, splenectomy, thoracotomy, median sternotomy, neoplastic thyroidectomy, rhinotomy, perineal herniorrhaphy or partial gastrectomy procedures. Excluded from the study were 2 dogs with incomplete transfusion records, 3 dogs that failed to meet the criteria for undergoing blood transfusion as already described, 4 dogs that underwent multiple surgical procedures on different occasions during the study period, 1 dog that had an incomplete medical record, and 1 dog that was misclassified as undergoing a splenectomy in the medical record. The final study included 207 dogs. The median age of dogs included in the study was 9 years (range, 0.5 to 17 years). Included in the study were 6 (2.9%) sexually intact females, 78 (37.7%) spayed females, 39 (18.8%) sexually intact males, and 84 (40.6%) castrated males. Sixty-two dog breeds were included in the study, including mixed breed (n = 47 [22.7%]), Labrador Retriever (32 [15.5%]), Golden Retriever (12 [5.8%]), German Shepherd Dog (11 [5.3%]), Beagle (7 [3.4%]), Border Collie (7 [3.4%]), Boxer (7 [3.4%]), Shetland Sheepdog (5 [2.4%]), American Staffordshire Terrier (3 [1.4%]), English Bulldog (3 [1.4%]), Dachshund (3 [1.4%]), Great Dane (3 [1.4%]), Shih Tzu (3 [1.4%]), and Yorkshire Terrier (3 [1.4%]). The remaining breeds were grouped as miscellaneous breeds (n = 61 [29.5%]). The median body weight of dogs included in the study was 26.7 kg (58.7 lb; range, 3.1 to 58.4 kg [6.8 to 128.5 lb]). Analysis by use of the Tukey-Kramer multiple comparison test revealed that mean body weight differed significantly among surgical types (Table 1). Multiple logistic regression analysis revealed that there was no association between age, sex, or breed and the need for transfusion JAVMA, Vol 247, No. 1, July 1, 2015
Table 1—Descriptive statistics by surgery type in 207 dogs. No. (%) that received a transfusion
Mean ± SEM age (y)
Mean ± SEM weight (kg)
27 (41.5) 6 (40.0) 4 (28.6) 4 (36.4) 2 (28.5)
9.6 ± 0.4a 9.5 ± 0.8 10.2 ± 0.8 8.1 ± 0.9 8.6 ± 1.2
27.9 ± 1.5 23.3 ± 3.2 27.8 ± 3.3 33.3 ± 3.7b 35.9 ± 4.7c
1 (4.5) 0 (0.0) 0 (0.0) 4 (9.3)
8.8 ± 0.7 7.4 ± 0.8 9.6 ± 0.8 7.5 ± 0.5a
18.6 ± 2.6b,c 25.1 ± 3.1 25.9 ± 3.3 23.2 ± 1.9
Splenectomy (n = 65) Liver lobectomy (n = 15) Liver lobectomy and splenectomy (n = 14) Partial gastrectomy (n = 11) Partial gastrectomy and splenectomy (n = 7) Perineal hernia repair (n = 22) Rhinotomy (n = 16) Neoplastic thyroidectomy (n = 14) Intrathoracic procedures (n = 43)
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Surgical procedure
a Mean age differed significantly (P = 0.015) between splenectomy and intrathoracic surgery groups. Mean weight differed significantly (P = 0.009) between partial gastrectomy and perineal herniorrhaphy groups. cMean weight differed significantly (P = 0.009) between partial gastrectomy and splenectomy and perineal herniorrhaphy groups. b
Table 2—Results of multivariable logistic regression evaluating the association between the need for a transfusion and surgical procedure, survival rate, sex, breed, age, and body weight for 207 dogs. Variable Surgical procedure Survival rate* Sex Breed Age (0.5–17 y) Weight (3.1–58.4 kg)
Coefficient
OR
5% lower confidence limit
95% upper confidence limit
P value
–0.41 –2.43 0.23 –0.0006 0.07 0.04
0.66 0.09 1.3 1.0 1.07 1.04
0.55 0.03 0.75 0.93 0.93 1.01
0.79 0.25 2.11 1.07 1.23 1.07
< 0.001 < 0.001 0.383 0.986 0.343 0.024
*Surviving to 2 weeks after surgery.
(Table 2). However, there was a significant association between the need for perioperative RBC transfusion and surgery type, survival rate at 2 weeks after surgery, and body weight. The odds of transfusion increased with body weight (OR, 1.039; P = 0.024). Surgical type—During the study period, there were 65 splenectomies, 15 liver lobectomies, 11 partial gastrectomies, 14 liver lobectomy and splenectomies, 7 partial gastrectomy and splenectomies, 14 neoplastic thyroidectomies, 16 rhinotomies, 22 perineal herniorrhaphies, and 43 intrathoracic procedures performed. Intrathoracic procedures performed included lung lobectomy (20), esophagotomy (4), exploratory for pyothorax (4), thoracic duct ligation and pericardectomy (4), mediastinal mass excision (2), mediastinal biopsy (2), thoracic wall excision (2), heart base mass excision (1), lymph node biopsy (1), lung biopsy (1), pericardectomy (1), and vascular ring anomaly repair (1). Transfusion—Of the 207 dogs included in the study, 48 (23.2%) required perioperative packed RBCs, whole blood, or bovine hemoglobin-based oxygen carriera transfusion. No cell-salvage procedures were performed in any dogs. The timing of transfusion was determined for dogs that received blood transfusions in each surgical category (Table 3). No significant differences were found in the proportions of dogs receiving transfusions during each time frame. The number of dogs that received blood transfusions in each surgical category was determined (Table 4). Patients within the intrathoracic group that received RBC transfusions included those undergoing thoracic duct ligation (n = JAVMA, Vol 247, No. 1, July 1, 2015
2), pyothorax exploratory (1), and mediastinal mass excision (1). No significant (P = 0.129) differences were found in the proportions of dogs that had a transfusion between the different intrathoracic procedures. A significant association was identified between RBC transfusion and surgical type. Compared with splenectomy, all other procedures had significantly (P < 0.001) lower odds of transfusion (OR, 0.159). Likewise, compared with liver lobectomy, all other procedures had significantly (P = 0.042) lower odds of transfusion (OR, 0.299). Conversely, compared with intrathoracic procedures, all other procedures had significantly (P = 0.007) greater odds of transfusion (OR, 5.524). Survival rate analysis—Of 207 total dogs in the study population, 173 (83.6%) survived. Of the 34 total dogs that did not survive to 2 weeks after surgery, 27 (79.4%) were euthanized, with the most common reason for euthanasia being poor prognosis resulting from continued decline in condition despite all efforts to stabilize the patient. The total number of dogs that survived in each surgical category was determined (Table 4). For those patients not requiring transfusion (159), 144 (90.6%) survived. Of the 48 total dogs in the study population that received perioperative RBC transfusions, 29 (60.4%) survived. The number of dogs that received blood transfusions and survived in each surgical category was determined (Table 4). As there were no significant (P ≥ 0.055) differences in the survival rate between procedure types in the intrathoracic category regardless of transfusion, the intrathoracic procedures were not categorized further for logistic regression. No significant (P ≥ 0.349) association was found between survival rate at 2 Scientific Reports
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Table 3—Number of 48 dogs receiving an RBC transfusion, organized according to procedure and timing of transfusion. Timing of RBC transfusion relative to surgery Procedure
Before
During
After
Before and during
4 0 0 1 0 0 0
8 0 1 1 1 0 0
7 1 2 2 1 1 3
2 0 0 0 0 0 0
Splenectomy Liver lobectomy Liver lobectomy and splenectomy Gastrectomy Gastrectomy and splenectomy Perineal hernia Thoracotomy
Before and During and after after 4 0 0 0 0 0 0
Before, during, and after
Total
P value
0 1 0 0 0 0 0
27 6 4 4 2 1 4
0.136 0.105 0.687 0.687 1.000 NA 0.486
2 4 1 0 0 0 1
Columns listing more than 1 period represent multiple single transfusions, each administered during a separate period of time. P values represent the outcome of a Fisher exact test performed on within-row data. The denominator for the Fisher exact test in each cell was the row total minus the cell value. Procedures with no patients receiving transfusions were excluded from the table. NA = Not applicable.
Table 4—Transfusion and 2-week survival rate data for each surgical procedure in 207 dogs. Transfusion*
Transfusion and survived†
No transfusion*
No transfusion and survived†
Total survivors*
Splenectomy (n = 65) Liver lobectomy (n = 15) Liver lobectomy and splenectomy (n = 14) Partial gastrectomy (n = 11) Gastrectomy and splenectomy (n = 7)
27 (42) 6 (40) 4 (29) 4 (36) 2 (29)
20 (74) 5 (83) 2 (50) 1 (25) 0 (0)
38 (58) 9 (60) 10 (71) 7 (64) 5 (71)
37 (97) 8 (89) 8 (80) 5 (71) 4 (80)
57 (88) 13 (87) 10 (71) 6 (55) 4 (57)
Neoplastic thyroidectomy (n = 14) Rhinotomy (n = 16) Perineal herniorrhaphy (n = 22) Intrathoracic procedures (n = 43) Total (n = 207)
0 (0) 0 (0) 1 (5) 4 (9) 48 (23)
NA NA 0 (0) 1 (25) 29 (60)
14 (100) 16 (100) 21 (95) 39 (91) 159 (77)
14 (100) 16 (100) 20 (95) 32 (82) 144 (91)
14 (100) 16 (100) 20 (91) 33 (77) 173 (84)
Surgical procedure
Values are number (%). *Denominator is within-row total number of dogs. †Denominator is number of dogs that received a transfusion or number of dogs that did not, as applicable. NA = Not applicable.
Table 5—Results of multivariable logistic regression evaluating the association between patient 2-week survival rate and surgery type, transfusion, sex, breed, age, and body weight in 207 dogs. Variable Surgical procedure Transfusion Sex Breed Age (0.5–17 y) Weight (3.1–58.4 kg)
Coefficient
OR
5% lower confidence limit
95% upper confidence limit
P value
–0.19 –2.45 0.08 –0.003 –0.06 –0.12
0.82 0.09 1.08 1.00 1.06 0.99
0.70 0.03 0.68 0.93 0.94 0.96
0.97 0.25 1.72 1.07 1.21 1.02
0.020 < 0.001 0.743 0.937 0.349 0.474
weeks after surgery and sex, breed, age, and body weight (Table 5). However, there was a negative association between survival rate and transfusion, with dogs that had a transfusion having lower odds of surviving to 2 weeks after surgery than those that did not have a transfusion (OR, 0.087; P < 0.001). Similarly, there was a negative association between survival rate at 2 weeks after surgery and surgery type, irrespective of RBC transfusion (OR, 0.824; P = 0.020). Compared with splenectomy, all other procedures had lower odds of the dogs’ surviving to 2 weeks after surgery (OR, 0.246; P = 0.008). Conversely, compared with partial gastrectomy, all other procedures had higher odds of the dogs’ surviving to 2 weeks after surgery (OR, 4.602; P = 0.029). Similarly, compared with thoracotomy, all other procedures had higher odds of the 88
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dogs’ surviving to 2 weeks after surgery (OR, 3.392; P = 0.014). Discussion Limited information has been published on the rate of perioperative RBC transfusion in dogs undergoing splenectomy, liver lobectomy, partial gastrectomy, thyroidectomy, rhinotomy, perineal herniorrhaphy, or intrathoracic procedures. Current resources indicate that there is increased risk of hemorrhage when performing these surgical procedures; however, to the authors’ knowledge, the number of patients undergoing these procedures that receive RBC transfusion has never been quantified.8–11,14–17 JAVMA, Vol 247, No. 1, July 1, 2015
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risk for severe hemorrhage.12,13 If our study population contained a greater number of dogs that underwent cardiovascular procedures, intrathoracic procedures could have been analyzed in subcategories rather than as a single group. Body weight was another variable found to be significantly related to increased odds of perioperative RBC transfusion. Although the only significant differences in mean body weight were found between patients undergoing partial gastrectomy and partial gastrectomy and splenectomy and those undergoing perineal herniorrhaphy, the lack of significant differences in mean body weight among all surgical types may reflect sample size and within-category variation. Many of the surgical procedures considered in this study are performed more often in medium- to large-breed dogs; therefore, it seems likely that the type of surgery performed would be associated with body weight, but this assertion was not confirmed in the present study. Large- and giantbreed dogs are often deep chested, making observation of organs in the thorax and cranial portion of the abdomen more difficult. In addition, some dogs in the study population could be considered overweight or obese. Obesity is an accepted risk factor for increased surgical difficulty because excess adipose tissue may impede the surgeon’s ability to view the surgical site and may also contribute to the slippage of ligatures.20,21 In this study, 61.2% of all dogs that underwent perioperative RBC transfusions survived. This result is similar to the results in a study by Callan et al,22 in which 61% of 307 dogs that received RBC transfusions survived to hospital discharge. In another study by Godinho-Cunha et al,23 15 dogs and cats received 19 RBC transfusions, and 60% survived to discharge from the hospital. In a study by Kerl and Hohenhaus,5 only 47% of 131 dogs receiving RBC transfusions survived to hospital discharge. Because these studies were specifically designed to examine patients receiving RBC transfusions, these investigators were unable to examine the survival rate in patients receiving RBC transfusion versus a control population that did not have a transfusion.5,22,23 They also examined a broader population of patients requiring blood transfusion, including those with nonsurgical hemorrhage, hemolysis, and ineffective erythropoiesis.5,22,23 In the present study, survival rate at 2 weeks after surgery was inversely related to perioperative blood transfusion, meaning that those dogs undergoing perioperative RBC transfusion had a decreased chance of surviving to 2 weeks after surgery. Because of the retrospective nature of this study and the variability of information consistently included in all patient medical records, multiple factors that likely affected postoperative survival rate were not included in statistical analysis, including underlying disease processes, concurrent illnesses, and patient physical status on the veterinary modification of the American Society of Anesthesiologists scale.24 Because these data were not consistently available and thus not included in statistical analysis, it is unclear what role RBC transfusion alone plays in the survival rate of surgical patients after surgery. It is likely that patients requiring preoperative RBC transfusion would have been classified as having a higher physical status on the veterinary modification of Scientific Reports
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Dogs undergoing splenectomy and those undergoing liver lobectomy had greater odds of receiving perioperative RBC transfusions than those undergoing the remaining surgical procedures. One possible explanation for this finding is that the most common reason for surgical removal of these organs is neoplasia. Organ removal as a result of neoplasia may be complicated because of increased blood supply to the tumors and sometimes decreased ability to view important structures as a result of tumor size.9 In addition, some tumors, especially hemangiosarcoma, a common splenic tumor, can often be friable and bleed easily when handled.18 Patients with splenic and liver tumors may even require preoperative or intraoperative RBC transfusion prior to surgical manipulation of the organs in cases of hemorrhagic peritoneal effusion.4,8 At the authors’ hospital (University of Missouri Veterinary Teaching Hospital), partial gastrectomy is most commonly performed to remove gastric tissue damaged secondary to gastric dilation and volvulus. It has been reported that during gastric dilation and volvulus, both mucosal and serosal hemorrhage occur.19 Meticulous surgical technique can prevent excessive hemorrhage during thyroidectomy, rhinotomy, perineal herniorrhaphy, and intrathoracic surgery.10,11,15,17 Patients undergoing these procedures are not often actively hemorrhaging at the time of surgery and generally do not require preoperative RBC transfusion. Although there is risk of hemorrhage in dogs undergoing these procedures,14–17 there were no significantly increased odds of RBC transfusion in the present study for these dogs, compared with those undergoing splenectomy or liver lobectomy. For the purposes of the present study, patients were included if they received one or multiple RBC transfusions in the preoperative, intraoperative, or postoperative period, as already defined. No significant differences were identified in the proportions of dogs receiving RBC transfusions during each of these periods; therefore, the data were grouped together as 1 perioperative period. In the case of patients receiving RBC transfusions in the preoperative period, the need for transfusion cannot be attributed to the surgical procedure itself. However, many patients receiving RBC transfusions in the preoperative period require transfusions because of acute blood loss secondary to surgical diseases such as trauma or neoplasia. It was for this reason that the authors opted to include those patients in the study. In the present study, patients undergoing intrathoracic procedures were not further categorized on the basis of specific procedure type for statistical analysis. This was because preliminary statistical analysis comparing the need for transfusion and survival rate among intrathoracic procedures revealed that there were no significant differences among specific procedures within this category. The population of dogs that underwent intrathoracic procedures in the present study included most patients undergoing lung lobectomy, none of which received transfusions. In addition, only a single patient underwent heart base mass excision, with another undergoing vascular ring anomaly repair, procedures that would generally be considered at greater
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the American Society of Anesthesiologists scale perioperatively and therefore would have had multiple factors contributing to an overall decreased chance of surviving.24 Likewise, patients needing perioperative transfusion likely had more complicated disease processes impacting their prognosis. Despite growing concerns over the risks versus benefits of RBC transfusions in anemic patients, there continues to be a lack of definitive guidelines for when blood products should be administered. Kerl and Hohenhaus5 developed a transfusion need scale on the basis of current hospital transfusion practices and available human literature in 1989; this scale assigned point values to criteria including anemia determined by PCV, history of rapid blood loss versus gradual decrease in RBC production, need for anesthesia, and clinical signs related to anemia, such as weakness, tachypnea, and tachycardia. It was concluded that although the scale identified many patients that required blood transfusions, some patients were assigned inappropriately high scores (increased need for transfusion) on the basis of clinical appearance.5 Conversely, the scale failed in dogs with acute blood loss that would not yet have changes in their PCV or anesthetized patients that would not acquire points for clinical signs such as tachypnea or weakness.5 The published scale was therefore considered inappropriate for use in the present study. Patients in the present study were examined post hoc for appropriateness of blood transfusion on the basis of the most current recommendations from multiple resources and examination of available medical records.2–6 The transfusion criteria were compared with the medical records of those patients that had received RBC transfusions. If those patients met one or more of the criteria, it was deemed that the clinician had medically sound and documented reasons for administering an RBC transfusion. Patients that did not receive RBC transfusion were not compared with the transfusion criteria to determine whether they potentially should have received a transfusion, given that some clinical information pertinent to the transfusion inclusion criteria was recorded only for those patients that received RBC transfusions. Change in patient PCV and estimated blood loss were not included in analysis because of inconsistent recording and variations in the amount of fluids administered perioperatively, estimated blood loss, and postoperative and post-transfusion PCV. Limitations of the present study included the retrospective nature and the variation in sample size within surgical groups. Also, the surgeries included in this study are only a sample of intraabdominal, intrathoracic, and extraabdominal or extrathoracic surgeries performed by veterinary surgeons, and many procedures that could have been included were not examined. The surgeries included were chosen by the authors as a sample of procedures for inclusion on the basis of the clinical impression that they were likely to be equally at risk for excessive hemorrhage and perioperative RBC transfusion requirement; however, they do not represent all surgeries performed by veterinarians. This potentially may have unintentionally created a bias in the study results. An additional limitation is that although the authors can document that the dogs that 90
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underwent transfusion met the inclusion criteria, they cannot state with certainty that all the dogs that did not receive a transfusion did not need one. In addition, 79.4% of nonsurvivors were euthanized, with the most common reason for euthanasia being poor prognosis resulting from continued decline in condition despite all efforts to stabilize the patient. Although the decision to perform euthanasia was made to relieve signs of pending natural death in most cases, it may have introduced bias into the survival rate data, inasmuch as outcome was determined by owner decision rather than natural causes. As veterinarians take on the task of increasingly difficult surgeries, the use of perioperative RBC transfusion may increase. Given this fact, hospitals where these procedures are being performed need to be prepared to administer such blood products, by keeping packed RBCs in stock and having readily available whole blood donors. According to our findings, dogs undergoing splenectomy and liver lobectomy were at increased risk for requiring perioperative RBC transfusion, compared with those undergoing concurrent liver lobectomy and splenectomy, partial gastrectomy, concurrent partial gastrectomy and splenectomy, rhinotomy, neoplastic thyroidectomy, perineal herniorrhaphy, or thoracotomy or median sternotomy. Further prospective study is required to determine how RBC transfusion affects survival rate in postoperative patients. a. b. c.
Oxyglobin, OPK Biotech LLC, Cambridge, Mass. NCSS 2007, Number Cruncher Statistical Software, Kaysville, Utah. Sigmaplot, version 12.0, SigmaStat Statistical Software, San Rafael, Calif.
References 1.
Jutkowitz LA, Rozanski EA, Moreau JA, et al. Massive transfusion in dogs: 15 cases (1997–2001). J Am Vet Med Assoc 2002;220:1664–1669. 2. Ari Jutkowitz L. Blood transfusion in the perioperative period. Clin Tech Small Anim Pract 2004;19:75–82. 3. Giacomo S, Otto CM. Shock. In: Tobias KM, Johnston SA, eds. Veterinary surgery: small animal. Philadelphia: Saunders Elsevier, 2012;73–93. 4. Herold LV, Devey JJ, Kirby R, et al. Clinical evaluation and management of hemoperitoneum in dogs. J Vet Emerg Crit Care 2008;18:40–53. 5. Kerl ME, Hohenhaus AE. Packed red blood cell transfusions in dogs: 131 cases (1989). J Am Vet Med Assoc 1993;202:1495– 1499. 6. Silverstein D, Campbell J. Fluid therapy. In: Tobias KM, Johnston SA, eds. Veterinary surgery: small animal. Philadelphia: Saunders Elsevier, 2012;43–72. 7. Risselada M, Ellison GW, Bacon NJ, et al. Comparison of 5 surgical techniques for partial liver lobectomy in the dog for intraoperative blood loss and surgical time. Vet Surg 2010;39:856– 862. 8. Marino DJ, Matthiesen DT, Fox PR, et al. Ventricular arrhythmias in dogs undergoing splenectomy: a prospective study. Vet Surg 1994;23:101–106. 9. Monarski CJ, Jaffe MH, Kass PH. Decreased surgical time with a vessel sealing device versus a surgical stapler in performance of canine splenectomy. J Am Anim Hosp Assoc 2014;50:42–45. 10. Burton CA, White RN. Review of the technique and complications of median sternotomy in the dog and cat. J Small Anim Pract 1996;37:516–522. 11. Radlinsky MG. Thoracic cavity. In: Tobias KM, Johnston SA, JAVMA, Vol 247, No. 1, July 1, 2015
13. 14. 15. 16. 17. 18.
19. 20. 21. 22. 23. 24.
1: epidemiologic, clinical characteristics as well as histopathologic diagnosis in 249 cases (2000–2011). Tierarztl Prax Ausg K Kleintiere Heimtiere 2012;40:250–260. Volk SW. Gastric dilatation-volvulus and bloat. In: Silverstein DC, Hopper K, eds. Small animal critical care medicine. St Louis: Saunders Elsevier, 2009;584–588. Van Goethem BE, Rosenveldt KW, Kirpenstein J. Monopolar versus bipolar electrocoagulation in canine laparoscopic ovariectomy: a nonrandomized, prospective, clinical trial. Vet Surg 2003;32:464–470. Chan DL. Metabolism and nutritional needs of surgical patients. In: Tobias KM, Johnston SA, eds. Veterinary surgery: small animal. Philadelphia: Saunders Elsevier, 2012;121–124. Callan MB, Oakley DA, Shofer FS, et al. Canine red blood cell transfusion practice. J Am Anim Hosp Assoc 1996;32:303–311. Godinho-Cunha LF, Ferreira RM, Silvestre-Ferreira AC. Whole blood transfusion in small animals: indications and effects. An Acad Bras Cienc 2011;83:611–617. Swanson EA, Mann FA. Preoperative patient assessment. In: Mann FA, Constantinescu GM, Yoon HY, eds. Fundamentals of small animal surgery. Ames, Iowa: Wiley-Blackwell, 2011;3–7.
From this month’s AJVR
Cardiovascular effects of equipotent doses of isoflurane alone and isoflurane plus fentanyl in New Zealand White rabbits (Oryctolagus cuniculus) Caitlin C. Tearney et al Objective—To determine effects of equipotent concentrations of fentanyl and isoflurane, compared with isoflurane alone, on cardiovascular variables in New Zealand White rabbits (Oryctolagus cuniculus). Animals—6 adult female New Zealand White rabbits. Procedures—Rabbits were anesthetized with isoflurane, and lungs were mechanically ventilated. The minimum alveolar concentration (MAC) of isoflurane alone (baseline) and with fentanyl administered IV to achieve 3 targeted plasma concentrations was determined for each rabbit by means of an electrical stimulus. Cardiovascular variables were measured in a separate experiment at 1.3X the isoflurane MAC and equipotent doses of isoflurane plus fentanyl at the same 3 targeted plasma concentrations. Blood samples were collected for measurement of blood gas variables and plasma fentanyl concentrations. Treatment effects were evaluated by repeated-measures ANOVA followed by 2-tailed paired t tests with sequentially rejective Bonferroni correction. Results—Mean ± SD MAC of isoflurane was 1.95 ± 0.27%. Mean measured plasma fentanyl concentrations of 4.97, 8.93, and 17.19 ng/mL reduced isoflurane MAC by 17%, 37%, and 56%, respectively. Mean measured plasma fentanyl concentrations during cardiovascular measurements were 5.49, 10.26, and 18.40 ng/mL. Compared with baseline measurements, heart rate was significantly lower at all 3 plasma fentanyl concentrations, mean arterial blood pressure and systemic vascular resistance were significantly higher at mean fentanyl concentrations of 10.26 and 18.40 ng/mL, and cardiac output was significantly higher at 18.40 ng of fentanyl/mL. Conclusions and Clinical Relevance—Administration of fentanyl in isoflurane-anesthetized rabbits resulted in improved mean arterial blood pressure and cardiac output, compared with isoflurane alone. This balanced anesthesia technique may prove useful in the management of clinical cases in this species. (Am J Vet Res 2015;76:591–598)
JAVMA, Vol 247, No. 1, July 1, 2015
July 2015
See the midmonth issues of JAVMA for the expanded table of contents for the AJVR or log on to avmajournals.avma.org for access to all the abstracts.
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