Perioperative goal-directed hemodynamic optimization using noninvasive cardiac output monitoring in major abdominal surgery: a prospective, randomized, multicenter, pragmatic trial: POEMAS Study (PeriOperative goal-directed thErapy in Major Abdominal Surgery).

BACKGROUND: In this study, our objective was to determine whether a perioperative hemodynamic protocol based on noninvasive cardiac output monitoring decreases the incidence of postoperative complications and hospital length of stay in major abdominal surgery patients requiring intensive care unit admission. Secondary objectives were the time to peristalsis recovery and the incidence of wound infection, anastomotic leaks, and mortality. METHODS: A randomized clinical trial was conducted in 6 tertiary hospitals. One hundred forty-two adult patients scheduled for open colorectal surgery, gastrectomy, or small bowel resection were enrolled. A hemodynamic protocol including fluid administration and vasoactive drugs based on arterial blood pressure, cardiac index, and stroke volume response was compared with standard practice. Patients were followed until hospital discharge (determined by a surgeon blinded to the study) or death. In contrast to previous studies, we designed a pragmatic trial (as opposed to explanatory trials) to mimic real practice and obtain maximal external validity for the study. RESULTS: Fluid administration was similar except for the number of colloid boluses (2.4 ± 1.8 [treated] vs 1.3 ± 1.4 [control]; P < 0.001) and packed red blood cell units (0.6 ± 1.3 [treated] vs 0.2 ± 0.6 [control]; P = 0.019). Dobutamine was used in 25% (intraoperatively) and 19.4% (postoperatively) of the treated patients versus 1.4% and 0% in the control group (P < 0.001). We have observed a reduction in reoperations in the treated group (5.6% vs 15.7%; P = 0.049). However, no significant differences were observed in overall complications (40% vs 41%; relative risk 0.99 [0.67-1.44]; P = 0.397), length of stay (11.5 [8-15] vs 10.5 [8-16]; P = 0.874), time to first flatus (62 hours [40-76] vs 72 hours [48-96]; P = 0.180), wound infection (7 vs 14; P = 0.085), anastomotic leaks (2 vs 5; P = 0.23), or mortality (4.2% vs 5.7%; P = 0.67). CONCLUSIONS: The results of our pragmatic study indicate that a perioperative hemodynamic protocol guided by a noninvasive cardiac output monitor was not associated with a decrease in the incidence of overall complications or length of stay in major abdominal surgery.

Arterial and plethysmographic waveform analysis in anesthetized patients with hypovolemia.

BACKGROUND: Respiratory-induced arterial and plethysmographic (pulse oximetry) waveform changes were shown to be good predictors of cardiac output response to increased preload. The aim of this study was to evaluate the reliability of arterial and plethysmographic waveform variables in patients with mild hypovolemia. METHODS: Patients undergoing autologous hemodilution were studied. After anesthesia induction, hemodilution was performed by withdrawing blood in steps of 2% of estimated circulating blood volume (ECBV), up to 20%. The patients who did not develop hypotension (systolic blood pressure < 80 mmHg) were studied. Arterial and plethysmographic waveforms were recorded and analyzed off-line at baseline and after each withdrawal of blood. Variations in arterial systolic and pulse pressure were analyzed using standard methods. Plethysmographic waveform variation and delta pulse oximetry plethysmography were determined by using pulse oximetry recordings. RESULTS: There were 33 study participants. Systolic blood pressure decreased by 11%, and heart rate increased from 73 to 76 beats/min after a 20% reduction of ECBV. Systolic pressure and pulse pressure variations increased (P < 0.005) after a 4% reduction of ECBV. The values of arterial pressure and pulse oximetry waveform variables almost doubled in value after a 20% reduction of ECBV. Systolic pressure variation was the most reliable variable during hypovolemia. Plethysmographic waveform variation increased significantly after a 6% reduction of ECBV and delta pulse oximetry plethysmography after an 8% reduction of ECBV. CONCLUSIONS: Arterial and pulse oximetry respiratory-induced changes in waveform variables are reliable indicators of mild hypovolemia in anesthetized patients. The pulse oximetry plethysmographic waveforms accurately reflect arterial waveforms during more progressive hypovolemia.