Original Study
Journal of Veterinary Emergency and Critical Care 24(4) 2014, pp 403–407 doi: 10.1111/vec.12197
Determination and validation of volume to be instilled for standardized intra-abdominal pressure measurement in dogs Leilani Ireland Way, DVM, MS and Eric Monnet, DVM, PhD, DACVS, DECVS Abstract
Objectives – The objectives of this study were to determine (1) most appropriate volume of saline to be infused into the bladder prior to intra-abdominal pressure (IAP) measurement, (2) to determine if a difference exists between IAP measurements before and after abdominal surgery, and (3) to assess the variability in IAP measurements associated with different saline volumes. Design – Prospective study. Setting – University teaching hospital. Animals – Fifteen female research dogs, 7 undergoing ovariohysterectomy (OHE), and 8 undergoing laparoscopy. Interventions – All dogs had urinary catheters placed and 4 consecutive IAP measurements measured using a different volume of instilled saline (0.25, 0.5, 1, and 2 mL/kg) at baseline. Measurements were repeated intraoperatively in laparoscopy dogs and postoperatively in OHE dogs. Measurements and main results – For both groups of dogs, the volume infused into the bladder significantly affected IAP measurement. An instilled volume of 1 mL/kg of saline produced the best correlation (R2 = 0.44, P = 0.04) between IAP measurement and laparoscopic insufflator pressure. The mean (±SD) preoperative IAP (cmH2 O) using 1 mL/kg instilled saline was 7.9 ± 1.4 and 9.6 ±1.9 for laparoscopy and OHE dogs, respectively. There was no difference in IAP before and after surgery in the dogs undergoing an OHE (P = 0.58). The volume of saline instilled into the bladder significantly affected the IAP (P = 0.0028). Conclusions – One milliliter per kilogram instilled saline is recommended for standardized IAP pressure measurement in dogs. IAP in clinically normal dogs was not affected by abdominal surgery. (J Vet Emerg Crit Care 2014; 24(4): 403–407) doi: 10.1111/vec.12197 Keywords: abdominal compartment syndrome, canine, intraabdominal hypertension
Introduction Abdominal compartment syndrome is characterized by adverse physiologic consequences due to an acute increase in intra-abdominal pressure (IAP).1 The clinical importance of increased IAP, also known as intraabdominal hypertension, has been well documented in human medicine.2–4 Intra-abdominal hypertension alters regional blood flow and impairs tissue perfusion, which may trigger the systemic inflammatory response syndrome and multiple organ failure.1
From the Department of Clinical Sciences, College of Veterinary Medicine, Colorado State University, Fort Collins, CO 80523. The authors declare no conflicts of interest. Address correspondence and reprint requests to Dr. Leilani Ireland Way, 300 West Drake Road, Fort Collins, CO 80523, USA. Email: [email protected] Submitted August 03, 2012; Accepted May 19, 2014. C Veterinary Emergency and Critical Care Society 2014
Abbreviations
IAP intra-abdominal pressure OHE ovariohysterectomy
The easiest method of IAP measurement in people is obtained using the urinary bladder (intravesicular technique), and provides consistent and accurate results compared to direct invasive measurements.5 This technique was first described by Kron,6 and involves placement of a Foley catheter into the urinary bladder and infusion of saline into the bladder via the catheter. The IAP is measured via a water manometer as the saline passively exits the urinary bladder. Although this technique of IAP measurement correlates with direct IAP measurement in dogs,7 the volume that should be infused into the urinary bladder of dogs for accurate IAP estimation has not been evaluated. 403
L. I. Way & E. Monnet
The volume infused into the urinary bladder for IAP measurement is important; if too much is infused the detrusor muscle will contract and falsely elevate IAP readings.8,9 In human medicine, this topic is controversial and recent literature supports the use of minimal instillation volume (2–10 mL) for IAP measurement.9,10 These lower volumes allow for passive emptying of the bladder and accurate IAP estimation. Because dogs vary in size and most are smaller than a typical person, it would make sense that some dogs may require less infusion volume, so as not to activate the detrusor muscle or not to stretch the wall of the bladder. The objectives of this study were to (1) quantify a dose of saline in milliliter per kilogram required for accurate IAP measurement, (2) determine if an abdominal surgery affects IAP in dogs, and (3) assess for interactions between the volume of saline instilled, and IAP measurements made before and after surgery.
Materials and Methods Fifteen female research dogs were enrolled into a prospective study, including 7 research beagles undergoing ovariohysterectomy (OHE) and 8 research hound dogs undergoing laparoscopy. The beagles were adopted out at the end of the study. The hound dogs were part of a continuing education laparoscopy lab and were humanely euthanized at the end of the study. The Institutional Animal Care and Use Committee at the study facility approved this protocol. Dogs were sedated with a combination of atropine,a an opioid,b,c and occasionally acepromazine.d Dogs were induced with either ketaminee and diazepamf or propofolg and diazepam. They were maintained on isoflurane-inhalanth anesthetic through their procedure. Foley urinary cathetersi (6–8 French) were placed and the urinary bladder was emptied. An open urinary collection system was connected to the Foley catheter with two three-way stopcocks. The stopcock closest to the subject had a water manometerj attached to it. The second stopcock was attached to a 20 mL syringe and liter bag of 0.9% sodium chloride, as previously described by Conzemius et al.11 The urinary bladder was emptied completely between each measurement and the manometer was zeroed at the level of the pubic symphysis before each measurement. Four consecutive IAP measurements (each with a different volume of saline) were obtained by the primary investigator (L.I.W.) at 2 timepoints: preoperatively in all dogs (under sedation), immediately postoperatively for the dogs in the OHE group (while the dogs were still under general anesthesia), and during laparoscopy in the dogs in the laparoscopy group. The first measurement was obtained with instillation of 0.25 mL/kg of 404
Table 1: Correlation coefficients between direct (by laparoscopy insufflator) and indirect (intravesicular) intra-abdominal pressure measurements at different volumes of saline instilled into the urinary bladder of 8 healthy female dogs
Volume of intravesicular saline
0.25 mL/kg
0.5 mL/kg
1 mL/kg
2 mL/kg
R2 P-value
0.016 0.73
0.328 0.08
0.441 0.04
0.239 0.15
saline, second with 0.5 mL/kg of saline, third with 1 mL/kg of saline, and final with 2 mL/kg of saline instilled into the urinary bladder. Dogs in the laparoscopy group were maintained in lateral recumbency. The abdomen was clipped and aseptically prepared for laparoscopic surgery. A cannula was placed percutaneously into the peritoneal cavity and the automatic insufflator was introduced. Carbon dioxide was then instilled into the peritoneal cavity until the pressure transducer attached to the insufflators indicated the desired pressure. This pressure was maintained by the automatic insufflator with additional carbon dioxide as needed. After each saline aliquot was instilled into the bladder, simultaneous measurements were recorded from the water manometer and pressure transducer on the insufflators. Measurements were taken during the laparoscopic procedure. All measurements were obtained with the animals in lateral recumbency at the end of expiration. Baseline IAP was defined as the IAP measured before OHE or before laparoscopy.
Statistical Methods Data were analyzed using a commercially available statistical software program.k IAP was normally distributed in this population. Linear regression was used to compare the measured IAP to insufflator pressure in laparoscopy dogs. ANOVA for repeated measures was used to evaluate the effect of abdominal surgery, volume of saline injected, and the interaction between surgery and volume of saline infused on IAP in the OHE group. Data were reported as mean ± SD. A P-value of
Journal of Veterinary Emergency and Critical Care 24(4) 2014, pp 403–407 doi: 10.1111/vec.12197
Determination and validation of volume to be instilled for standardized intra-abdominal pressure measurement in dogs Leilani Ireland Way, DVM, MS and Eric Monnet, DVM, PhD, DACVS, DECVS Abstract
Objectives – The objectives of this study were to determine (1) most appropriate volume of saline to be infused into the bladder prior to intra-abdominal pressure (IAP) measurement, (2) to determine if a difference exists between IAP measurements before and after abdominal surgery, and (3) to assess the variability in IAP measurements associated with different saline volumes. Design – Prospective study. Setting – University teaching hospital. Animals – Fifteen female research dogs, 7 undergoing ovariohysterectomy (OHE), and 8 undergoing laparoscopy. Interventions – All dogs had urinary catheters placed and 4 consecutive IAP measurements measured using a different volume of instilled saline (0.25, 0.5, 1, and 2 mL/kg) at baseline. Measurements were repeated intraoperatively in laparoscopy dogs and postoperatively in OHE dogs. Measurements and main results – For both groups of dogs, the volume infused into the bladder significantly affected IAP measurement. An instilled volume of 1 mL/kg of saline produced the best correlation (R2 = 0.44, P = 0.04) between IAP measurement and laparoscopic insufflator pressure. The mean (±SD) preoperative IAP (cmH2 O) using 1 mL/kg instilled saline was 7.9 ± 1.4 and 9.6 ±1.9 for laparoscopy and OHE dogs, respectively. There was no difference in IAP before and after surgery in the dogs undergoing an OHE (P = 0.58). The volume of saline instilled into the bladder significantly affected the IAP (P = 0.0028). Conclusions – One milliliter per kilogram instilled saline is recommended for standardized IAP pressure measurement in dogs. IAP in clinically normal dogs was not affected by abdominal surgery. (J Vet Emerg Crit Care 2014; 24(4): 403–407) doi: 10.1111/vec.12197 Keywords: abdominal compartment syndrome, canine, intraabdominal hypertension
Introduction Abdominal compartment syndrome is characterized by adverse physiologic consequences due to an acute increase in intra-abdominal pressure (IAP).1 The clinical importance of increased IAP, also known as intraabdominal hypertension, has been well documented in human medicine.2–4 Intra-abdominal hypertension alters regional blood flow and impairs tissue perfusion, which may trigger the systemic inflammatory response syndrome and multiple organ failure.1
From the Department of Clinical Sciences, College of Veterinary Medicine, Colorado State University, Fort Collins, CO 80523. The authors declare no conflicts of interest. Address correspondence and reprint requests to Dr. Leilani Ireland Way, 300 West Drake Road, Fort Collins, CO 80523, USA. Email: [email protected] Submitted August 03, 2012; Accepted May 19, 2014. C Veterinary Emergency and Critical Care Society 2014
Abbreviations
IAP intra-abdominal pressure OHE ovariohysterectomy
The easiest method of IAP measurement in people is obtained using the urinary bladder (intravesicular technique), and provides consistent and accurate results compared to direct invasive measurements.5 This technique was first described by Kron,6 and involves placement of a Foley catheter into the urinary bladder and infusion of saline into the bladder via the catheter. The IAP is measured via a water manometer as the saline passively exits the urinary bladder. Although this technique of IAP measurement correlates with direct IAP measurement in dogs,7 the volume that should be infused into the urinary bladder of dogs for accurate IAP estimation has not been evaluated. 403
L. I. Way & E. Monnet
The volume infused into the urinary bladder for IAP measurement is important; if too much is infused the detrusor muscle will contract and falsely elevate IAP readings.8,9 In human medicine, this topic is controversial and recent literature supports the use of minimal instillation volume (2–10 mL) for IAP measurement.9,10 These lower volumes allow for passive emptying of the bladder and accurate IAP estimation. Because dogs vary in size and most are smaller than a typical person, it would make sense that some dogs may require less infusion volume, so as not to activate the detrusor muscle or not to stretch the wall of the bladder. The objectives of this study were to (1) quantify a dose of saline in milliliter per kilogram required for accurate IAP measurement, (2) determine if an abdominal surgery affects IAP in dogs, and (3) assess for interactions between the volume of saline instilled, and IAP measurements made before and after surgery.
Materials and Methods Fifteen female research dogs were enrolled into a prospective study, including 7 research beagles undergoing ovariohysterectomy (OHE) and 8 research hound dogs undergoing laparoscopy. The beagles were adopted out at the end of the study. The hound dogs were part of a continuing education laparoscopy lab and were humanely euthanized at the end of the study. The Institutional Animal Care and Use Committee at the study facility approved this protocol. Dogs were sedated with a combination of atropine,a an opioid,b,c and occasionally acepromazine.d Dogs were induced with either ketaminee and diazepamf or propofolg and diazepam. They were maintained on isoflurane-inhalanth anesthetic through their procedure. Foley urinary cathetersi (6–8 French) were placed and the urinary bladder was emptied. An open urinary collection system was connected to the Foley catheter with two three-way stopcocks. The stopcock closest to the subject had a water manometerj attached to it. The second stopcock was attached to a 20 mL syringe and liter bag of 0.9% sodium chloride, as previously described by Conzemius et al.11 The urinary bladder was emptied completely between each measurement and the manometer was zeroed at the level of the pubic symphysis before each measurement. Four consecutive IAP measurements (each with a different volume of saline) were obtained by the primary investigator (L.I.W.) at 2 timepoints: preoperatively in all dogs (under sedation), immediately postoperatively for the dogs in the OHE group (while the dogs were still under general anesthesia), and during laparoscopy in the dogs in the laparoscopy group. The first measurement was obtained with instillation of 0.25 mL/kg of 404
Table 1: Correlation coefficients between direct (by laparoscopy insufflator) and indirect (intravesicular) intra-abdominal pressure measurements at different volumes of saline instilled into the urinary bladder of 8 healthy female dogs
Volume of intravesicular saline
0.25 mL/kg
0.5 mL/kg
1 mL/kg
2 mL/kg
R2 P-value
0.016 0.73
0.328 0.08
0.441 0.04
0.239 0.15
saline, second with 0.5 mL/kg of saline, third with 1 mL/kg of saline, and final with 2 mL/kg of saline instilled into the urinary bladder. Dogs in the laparoscopy group were maintained in lateral recumbency. The abdomen was clipped and aseptically prepared for laparoscopic surgery. A cannula was placed percutaneously into the peritoneal cavity and the automatic insufflator was introduced. Carbon dioxide was then instilled into the peritoneal cavity until the pressure transducer attached to the insufflators indicated the desired pressure. This pressure was maintained by the automatic insufflator with additional carbon dioxide as needed. After each saline aliquot was instilled into the bladder, simultaneous measurements were recorded from the water manometer and pressure transducer on the insufflators. Measurements were taken during the laparoscopic procedure. All measurements were obtained with the animals in lateral recumbency at the end of expiration. Baseline IAP was defined as the IAP measured before OHE or before laparoscopy.
Statistical Methods Data were analyzed using a commercially available statistical software program.k IAP was normally distributed in this population. Linear regression was used to compare the measured IAP to insufflator pressure in laparoscopy dogs. ANOVA for repeated measures was used to evaluate the effect of abdominal surgery, volume of saline injected, and the interaction between surgery and volume of saline infused on IAP in the OHE group. Data were reported as mean ± SD. A P-value of
