OBES SURG DOI 10.1007/s11695-014-1329-4
ORIGINAL CONTRIBUTIONS
Perioperative Fluid Guidance with Transthoracic Echocardiography and Pulse-Contour Device in Morbidly Obese Patients Tomi Pösö & Ola Winsö & Roman Aroch & Doris Kesek
# Springer Science+Business Media New York 2014
Abstract Background In bariatric surgery, non- or mini-invasive modalities for cardiovascular monitoring are addressed to meet individual variability in hydration needs. The aim of the study was to compare conventional monitoring to an individualized goal-directed therapy (IGDT) regarding the need of perioperative fluids and cardiovascular stability. Methods Fifty morbidly obese patients were consecutively scheduled for laparoscopic bariatric surgery (ClinicalTrials.gov Identifier: NCT01873183). The intervention group (IG, n=30) was investigated preoperatively with transthoracic echocardiography (TTE) and rehydrated with colloid fluids if a low level of venous return was detected. During surgery, IGDT was continued with a pulse-contour device (FloTrac™). In the control group (CG, n=20), conventional monitoring was conducted. The type and amount of perioperative fluids infused, vasoactive/inotropic drugs administered, and blood pressure levels were registered. Results In the IG, 213±204 mL colloid fluids were administered as preoperative rehydration vs. no preoperative fluids in the CG (p8 mL/kg IBW to maintain accuracy of the FloTrac device. In the control group, slightly lower tidal volumes were accepted (>7 mL/ kg IBW). During pneumoperitoneum, intra-abdominal pressure levels were kept at 12–14 mmHg (always 70 % of the pre-induction baseline and/or ≥65 mmHg, heart rate ≥50/min] were obtained by i.v. administration of colloids
OBES SURG Fig. 1 The flow chart of the perioperative logistics. IGDT individualized goal-directed therapy; asterisk, conventional monitoring was conducted by ECG, heart rate, SpO2, and blood pressure measurements (noninvasively in the control group and invasively in the intervention group); TTE transthoracic echocardiography, MAP mean arterial pressure, SVV stroke volume variation, CO cardiac output, SV stroke volume of the left ventricle, RSI rapid sequence induction, IAP intraabdominal pressure, IBW ideal body weight, ECG electrocardiogram, SpO2 peripheral oxygen saturation
3 mL/kg IBW and/or ephedrine and/or phenylephrine. The administration of these drugs and fluids was conducted by the anesthetist in charge. Neither TTE nor preoperative rehydration was applied in the control group. In the operating room, before pneumoperitoneum, prophylactic i.v. antibiotics were administered in a total of 550 mL crystalloids (NaCl 0.9 %, Fresenius Kabi, Sweden). Infusion of buffered glucose solution (25 mg/mL, Fresenius Kabi, Sweden) at a rate of 1.5 mL/kg IBW/h was initiated. Postoperatively, infusion of buffered glucose solution (50 mg/mL) was administered at a fixed rate of 100 mL/h. In addition, during the stay at the postoperative recovery unit, 850 mL of crystalloids (antibiotics, paracetamol, and NSAIDs) were infused. Administration of these fluids was identical for both groups.
The Intervention Group In the intervention group, the individualized goal-directed therapy was implemented in two steps. First, preoperative transthoracic echocardiography scanning and rehydration was performed 45 min before surgery. Second, maintained guidance of the fluid therapy during surgery was conducted utilizing the FloTrac device. The preoperative rehydration was implemented by 6 mL colloid fluids (Volulyte™, Fresenius Kabi, Sweden)/kg ideal body weight [7] if a low level of venous return was detected by TTE [10]. After a colloid bolus, the second TTE investigation was performed to check the level of venous return. If remaining hypovolemia was found, additional colloids 3 mL/ kg IBW was given. Moreover, if systolic left ventricular
OBES SURG
failure was detected in the preoperative TTE, infusion of dobutamine 3–4 μg/kg IBW was started before induction of anesthesia. Stroke volume variation ≥12 % was used as a threshold for administration of additional colloids 3 mL/kg/IBW during surgery. In addition to fluids, i.v. ephedrine and/or phenylephrine was used when necessary to ensure adequate tissue perfusion (MAP >70 % of the baseline and/or ≥65 mmHg, cardiac index ≥2.0, and heart rate ≥50/min). Data Gathering The baseline for MAP and heart rate was registered in a supine position before induction of anesthesia in both groups. Five minutes after endotracheal intubation, before pneumoperitoneum, and i.v. antibiotics, the conventional and the first FloTrac-derived functional hemodynamic parameters [stroke volume variation (SVV), stroke volume (SV), cardiac output (CO), and cardiac index (CI)] were collected. From then on, registration of hemodynamic parameters was performed every 5 min. The FloTrac-guided fluid administration and monitoring was terminated at the end of surgery. Conventional monitoring was implemented at the postoperative recovery unit (POP) in both groups. Blood samples were collected at the day of surgery and on the first postoperative day between 6:00 and 6:30 a.m. Urinary output was measured hourly at the postoperative recovery unit only. In the intervention group, IAP levels were measured twice via a urinary drain with the Foley catheter system. The first IAP measurement was conducted before pneumoperitoneum in general anesthesia ensuring zero train-of-four ratio, a supine position, zero PEEP, and an expiratory pause of 10 s. The pubic bone was used as the reference level. The second measurement was carried out 4 h postoperatively without significant postoperative nausea and vomiting (PONV) and pain [visual analog scale (VAS) ≤3/10] in a supine position. Length of stay at POP, length of hospital stay (LOS), primary and 30-day outcome, and complications were registered in both groups.
Pulse-Contour Device FloTrac/Vigileo™ The FloTrac/Vigileo device produces continuous data of stroke volume and cardiac output. The calculations are based on an analysis of the pulse pressure of the arterial waveform in the FloTrac algorithm. No manual calibration is needed. The device has been utilized in many kinds of surgery [25–28], even in laparoscopic surgery [29]. The third generation software (version 3.01) was used. In this software, the conversion factor Khi (K) accounting for arterial compliance is updated every 60 s automatically. Consequently, the 1-min time frame for the display was used and data were registered a minimum of 1 min from treatments that might have an effect on arterial compliance (e.g., administration of potential i.v. drugs or a position change) [30, 31]. All measurements with the FloTrac were performed in general anesthesia, controlled ventilation with tidal volumes >8 mL/kg IBW, and without arrhythmias in sinus rhythm. Possible arrhythmias or other nonsinus rhythms were corrected before reading of mean arterial pressures and the FloTrac-derived functional hemodynamic parameters. Individuals with persistent nonsinus rhythms were excluded from the study. Statistical Methods The data processing was done with Statistical Package for Social Sciences (SPSS) version 20.0. All data were expressed as mean values±SD if not otherwise stated. Levene’s test was used to assess equality of variances of the data. Kolmogorov– Smirnov tests for normality were performed. Two-tailed Student’s t test and/or Mann–Whitney U test were used for comparisons of mean values. When appropriate, χ2 and/or Fisher’s exact tests were performed for comparison of binominal data. Two-tailed p values less than 0.05 were considered statistically significant. Power and a sample size of the study were calculated on the primary variable total fluids given. A minimum of 23 subjects in each group would be needed to achieve power at 0.8 (power=1−β=0.8) with an α level 0.05, β=0.2, and a standard deviation of 600 mL to detect a 500-mL difference in overall fluids given.
Protocol for TTE All study subjects in the intervention group were investigated preoperatively in a supine position with transthoracic echocardiography with the main focus on the level of venous return and screening of heart function. Criteria for hypovolemia (i.e., low level of venous return) were estimated right atrial pressure (eRAP) 10 mmHg. Right atrial pressures were assessed by transthoracic echocardiography, converting IVC diameter and IVCCI to RAP [10, 24]. Ultrasound devices (Sequoia-512, Acuson-Siemens, Mountain View, CA or Vivid 6, GE Vingmed, Horten, Norway) were used for this purpose.
Results In the intervention group, four subjects were excluded during the study period due to inadequate acquisition circumstances in subcostal windows (n=3) and persistent nodal rhythm after the start of infusion of remifentanil (n=1). Consequently, data of 26 subjects in the intervention group and 20 controls were used for the statistics. Patient demographics were similar in both groups. Preoperative loss of weight (% of TBW) at 3 weeks was 8.8±1.8 in the intervention group compared to
OBES SURG
8.5±2.0 in the CG (NS). In the intervention group, the prevalence of preoperative hypovolemia was 13/26, euvolemia 12/ 26, and hypervolemia 1/26. Patient characteristics and comorbidities are summarized in Table 1. No differences in time for surgery, consumption of anesthetics, length of stay at POP, or length of hospital stay were found between the groups. No postoperative renal failure was found. Thirty-day mortality rate was 0 in both groups. One patient was converted to open surgery due to multiple adherences and another patient was reoperated due to postoperative tachycardia (bleeding), both in the intervention group. The perioperative data is summarized in Table 2. Overall, more fluids (crystalloids + colloids) were administered in the intervention group compared to the CG (4,053± 734 vs. 3,499±342 mL, respectively; p=0.009). Preoperative colloid fluids were only administered in the intervention group (213±204 mL) compared to no preoperative rehydration in the CG (p
ORIGINAL CONTRIBUTIONS
Perioperative Fluid Guidance with Transthoracic Echocardiography and Pulse-Contour Device in Morbidly Obese Patients Tomi Pösö & Ola Winsö & Roman Aroch & Doris Kesek
# Springer Science+Business Media New York 2014
Abstract Background In bariatric surgery, non- or mini-invasive modalities for cardiovascular monitoring are addressed to meet individual variability in hydration needs. The aim of the study was to compare conventional monitoring to an individualized goal-directed therapy (IGDT) regarding the need of perioperative fluids and cardiovascular stability. Methods Fifty morbidly obese patients were consecutively scheduled for laparoscopic bariatric surgery (ClinicalTrials.gov Identifier: NCT01873183). The intervention group (IG, n=30) was investigated preoperatively with transthoracic echocardiography (TTE) and rehydrated with colloid fluids if a low level of venous return was detected. During surgery, IGDT was continued with a pulse-contour device (FloTrac™). In the control group (CG, n=20), conventional monitoring was conducted. The type and amount of perioperative fluids infused, vasoactive/inotropic drugs administered, and blood pressure levels were registered. Results In the IG, 213±204 mL colloid fluids were administered as preoperative rehydration vs. no preoperative fluids in the CG (p8 mL/kg IBW to maintain accuracy of the FloTrac device. In the control group, slightly lower tidal volumes were accepted (>7 mL/ kg IBW). During pneumoperitoneum, intra-abdominal pressure levels were kept at 12–14 mmHg (always 70 % of the pre-induction baseline and/or ≥65 mmHg, heart rate ≥50/min] were obtained by i.v. administration of colloids
OBES SURG Fig. 1 The flow chart of the perioperative logistics. IGDT individualized goal-directed therapy; asterisk, conventional monitoring was conducted by ECG, heart rate, SpO2, and blood pressure measurements (noninvasively in the control group and invasively in the intervention group); TTE transthoracic echocardiography, MAP mean arterial pressure, SVV stroke volume variation, CO cardiac output, SV stroke volume of the left ventricle, RSI rapid sequence induction, IAP intraabdominal pressure, IBW ideal body weight, ECG electrocardiogram, SpO2 peripheral oxygen saturation
3 mL/kg IBW and/or ephedrine and/or phenylephrine. The administration of these drugs and fluids was conducted by the anesthetist in charge. Neither TTE nor preoperative rehydration was applied in the control group. In the operating room, before pneumoperitoneum, prophylactic i.v. antibiotics were administered in a total of 550 mL crystalloids (NaCl 0.9 %, Fresenius Kabi, Sweden). Infusion of buffered glucose solution (25 mg/mL, Fresenius Kabi, Sweden) at a rate of 1.5 mL/kg IBW/h was initiated. Postoperatively, infusion of buffered glucose solution (50 mg/mL) was administered at a fixed rate of 100 mL/h. In addition, during the stay at the postoperative recovery unit, 850 mL of crystalloids (antibiotics, paracetamol, and NSAIDs) were infused. Administration of these fluids was identical for both groups.
The Intervention Group In the intervention group, the individualized goal-directed therapy was implemented in two steps. First, preoperative transthoracic echocardiography scanning and rehydration was performed 45 min before surgery. Second, maintained guidance of the fluid therapy during surgery was conducted utilizing the FloTrac device. The preoperative rehydration was implemented by 6 mL colloid fluids (Volulyte™, Fresenius Kabi, Sweden)/kg ideal body weight [7] if a low level of venous return was detected by TTE [10]. After a colloid bolus, the second TTE investigation was performed to check the level of venous return. If remaining hypovolemia was found, additional colloids 3 mL/ kg IBW was given. Moreover, if systolic left ventricular
OBES SURG
failure was detected in the preoperative TTE, infusion of dobutamine 3–4 μg/kg IBW was started before induction of anesthesia. Stroke volume variation ≥12 % was used as a threshold for administration of additional colloids 3 mL/kg/IBW during surgery. In addition to fluids, i.v. ephedrine and/or phenylephrine was used when necessary to ensure adequate tissue perfusion (MAP >70 % of the baseline and/or ≥65 mmHg, cardiac index ≥2.0, and heart rate ≥50/min). Data Gathering The baseline for MAP and heart rate was registered in a supine position before induction of anesthesia in both groups. Five minutes after endotracheal intubation, before pneumoperitoneum, and i.v. antibiotics, the conventional and the first FloTrac-derived functional hemodynamic parameters [stroke volume variation (SVV), stroke volume (SV), cardiac output (CO), and cardiac index (CI)] were collected. From then on, registration of hemodynamic parameters was performed every 5 min. The FloTrac-guided fluid administration and monitoring was terminated at the end of surgery. Conventional monitoring was implemented at the postoperative recovery unit (POP) in both groups. Blood samples were collected at the day of surgery and on the first postoperative day between 6:00 and 6:30 a.m. Urinary output was measured hourly at the postoperative recovery unit only. In the intervention group, IAP levels were measured twice via a urinary drain with the Foley catheter system. The first IAP measurement was conducted before pneumoperitoneum in general anesthesia ensuring zero train-of-four ratio, a supine position, zero PEEP, and an expiratory pause of 10 s. The pubic bone was used as the reference level. The second measurement was carried out 4 h postoperatively without significant postoperative nausea and vomiting (PONV) and pain [visual analog scale (VAS) ≤3/10] in a supine position. Length of stay at POP, length of hospital stay (LOS), primary and 30-day outcome, and complications were registered in both groups.
Pulse-Contour Device FloTrac/Vigileo™ The FloTrac/Vigileo device produces continuous data of stroke volume and cardiac output. The calculations are based on an analysis of the pulse pressure of the arterial waveform in the FloTrac algorithm. No manual calibration is needed. The device has been utilized in many kinds of surgery [25–28], even in laparoscopic surgery [29]. The third generation software (version 3.01) was used. In this software, the conversion factor Khi (K) accounting for arterial compliance is updated every 60 s automatically. Consequently, the 1-min time frame for the display was used and data were registered a minimum of 1 min from treatments that might have an effect on arterial compliance (e.g., administration of potential i.v. drugs or a position change) [30, 31]. All measurements with the FloTrac were performed in general anesthesia, controlled ventilation with tidal volumes >8 mL/kg IBW, and without arrhythmias in sinus rhythm. Possible arrhythmias or other nonsinus rhythms were corrected before reading of mean arterial pressures and the FloTrac-derived functional hemodynamic parameters. Individuals with persistent nonsinus rhythms were excluded from the study. Statistical Methods The data processing was done with Statistical Package for Social Sciences (SPSS) version 20.0. All data were expressed as mean values±SD if not otherwise stated. Levene’s test was used to assess equality of variances of the data. Kolmogorov– Smirnov tests for normality were performed. Two-tailed Student’s t test and/or Mann–Whitney U test were used for comparisons of mean values. When appropriate, χ2 and/or Fisher’s exact tests were performed for comparison of binominal data. Two-tailed p values less than 0.05 were considered statistically significant. Power and a sample size of the study were calculated on the primary variable total fluids given. A minimum of 23 subjects in each group would be needed to achieve power at 0.8 (power=1−β=0.8) with an α level 0.05, β=0.2, and a standard deviation of 600 mL to detect a 500-mL difference in overall fluids given.
Protocol for TTE All study subjects in the intervention group were investigated preoperatively in a supine position with transthoracic echocardiography with the main focus on the level of venous return and screening of heart function. Criteria for hypovolemia (i.e., low level of venous return) were estimated right atrial pressure (eRAP) 10 mmHg. Right atrial pressures were assessed by transthoracic echocardiography, converting IVC diameter and IVCCI to RAP [10, 24]. Ultrasound devices (Sequoia-512, Acuson-Siemens, Mountain View, CA or Vivid 6, GE Vingmed, Horten, Norway) were used for this purpose.
Results In the intervention group, four subjects were excluded during the study period due to inadequate acquisition circumstances in subcostal windows (n=3) and persistent nodal rhythm after the start of infusion of remifentanil (n=1). Consequently, data of 26 subjects in the intervention group and 20 controls were used for the statistics. Patient demographics were similar in both groups. Preoperative loss of weight (% of TBW) at 3 weeks was 8.8±1.8 in the intervention group compared to
OBES SURG
8.5±2.0 in the CG (NS). In the intervention group, the prevalence of preoperative hypovolemia was 13/26, euvolemia 12/ 26, and hypervolemia 1/26. Patient characteristics and comorbidities are summarized in Table 1. No differences in time for surgery, consumption of anesthetics, length of stay at POP, or length of hospital stay were found between the groups. No postoperative renal failure was found. Thirty-day mortality rate was 0 in both groups. One patient was converted to open surgery due to multiple adherences and another patient was reoperated due to postoperative tachycardia (bleeding), both in the intervention group. The perioperative data is summarized in Table 2. Overall, more fluids (crystalloids + colloids) were administered in the intervention group compared to the CG (4,053± 734 vs. 3,499±342 mL, respectively; p=0.009). Preoperative colloid fluids were only administered in the intervention group (213±204 mL) compared to no preoperative rehydration in the CG (p
