Estimation of the difference between peritoneal microenvironment and core body temperature during laparoscopic surgery - a prospective observational study.

Maintaining patients' temperature during surgery is beneficial since hypothermia has been linked with perioperative complications. Laparoscopic surgery involves the insufflation of carbon dioxide (CO2) into the peritoneal cavity and has become the standard in many surgical indications since it is associated with better and faster recovery. However, the use of cold and dry CO2 insufflation can lead to perioperative hypothermia. We aimed to assess the difference between intraperitoneal and core temperatures during laparoscopic surgery and evaluate the influence of duration and CO2 insufflation volume by fitting a mixed generalized additive model. In this prospective observational single-center cohort trial, we included patients aged over 17 with American Society of Anesthesiology risk scores I to III undergoing laparoscopic surgery. Anesthesia, ventilation, and analgesia followed standard protocols, while patients received active warming using blankets and warmed fluids. Temperature data, CO2 ventilation parameters, and intraabdominal pressure were collected. We recruited 51 patients. The core temperature was maintained above 36 °C and progressively raised toward 37 °C as pneumoperitoneum time passed. In contrast, the intraperitoneal temperature decreased, thus creating a widening difference from 0.4 [25th-75th percentile: 0.2-0.8] °C at the beginning to 2.3 [2.1-2.3] °C after 240 min. Pneumoperitoneum duration and CO2 insufflation volume significantly increased this temperature difference (P < 0.001 for both parameters). Core vs. intraperitoneal temperature difference increased linearly by 0.01 T °C per minute of pneumoperitoneum time up to 120 min and then 0.05 T °C per minute. Each insufflated liter per unit of time, i.e. every 10 min, increased the temperature difference by approximately 0.009 T °C. Our findings highlight the impact of pneumoperitoneum duration and CO2 insufflation volume on the difference between core and intraperitoneal temperatures. Implementing adequate external warming during laparoscopic surgery effectively maintains core temperature despite the use of dry and unwarmed CO2 gases, but peritoneal hypothermia remains a concern, suggesting the importance of further research into regional effects.Trial registration: Clinicaltrials.gov: NCT04294758.

Cardiac index-guided therapy to maintain optimised postinduction cardiac index in high-risk patients having major open abdominal surgery: the multicentre randomised iPEGASUS trial.

BACKGROUND: It is unclear whether optimising intraoperative cardiac index can reduce postoperative complications. We tested the hypothesis that maintaining optimised postinduction cardiac index during and for the first 8 h after surgery reduces the incidence of a composite outcome of complications within 28 days after surgery compared with routine care in high-risk patients having elective major open abdominal surgery. METHODS: In three German and two Spanish centres, high-risk patients having elective major open abdominal surgery were randomised to cardiac index-guided therapy to maintain optimised postinduction cardiac index (cardiac index at which pulse pressure variation was <12%) during and for the first 8 h after surgery using intravenous fluids and dobutamine or to routine care. The primary outcome was the incidence of a composite outcome of moderate or severe complications within 28 days after surgery. RESULTS: We analysed 318 of 380 enrolled subjects. The composite primary outcome occurred in 84 of 152 subjects (55%) assigned to cardiac index-guided therapy and in 77 of 166 subjects (46%) assigned to routine care (odds ratio: 1.87, 95% confidence interval: 1.03-3.39, P=0.038). Per-protocol analyses confirmed the results of the primary outcome analysis. CONCLUSIONS: Maintaining optimised postinduction cardiac index during and for the first 8 h after surgery did not reduce, and possibly increased, the incidence of a composite outcome of complications within 28 days after surgery compared with routine care in high-risk patients having elective major open abdominal surgery. Clinicians should not strive to maintain optimised postinduction cardiac index during and after surgery in expectation of reducing complications. CLINICAL TRIAL REGISTRATION: NCT03021525.

Intraabdominal Pressure Targeted Positive End-expiratory Pressure during Laparoscopic Surgery: An Open-label, Nonrandomized, Crossover, Clinical Trial.

BACKGROUND: Pneumoperitoneum for laparoscopic surgery is associated with a rise of driving pressure. The authors aimed to assess the effects of positive end-expiratory pressure (PEEP) on driving pressure at varying intraabdominal pressure levels. It was hypothesized that PEEP attenuates pneumoperitoneum-related rises in driving pressure. METHODS: Open-label, nonrandomized, crossover, clinical trial in patients undergoing laparoscopic cholecystectomy. "Targeted PEEP" (2 cm H2O above intraabdominal pressure) was compared with "standard PEEP" (5 cm H2O), with respect to the transpulmonary and respiratory system driving pressure at three predefined intraabdominal pressure levels, and each patient was ventilated with two levels of PEEP at the three intraabdominal pressure levels in the same sequence. The primary outcome was the difference in transpulmonary driving pressure between targeted PEEP and standard PEEP at the three levels of intraabdominal pressure. RESULTS: Thirty patients were included and analyzed. Targeted PEEP was 10, 14, and 17 cm H2O at intraabdominal pressure of 8, 12, and 15 mmHg, respectively. Compared to standard PEEP, targeted PEEP resulted in lower median transpulmonary driving pressure at intraabdominal pressure of 8 mmHg (7 [5 to 8] vs. 9 [7 to 11] cm H2O; P = 0.010; difference 2 [95% CI 0.5 to 4 cm H2O]); 12 mmHg (7 [4 to 9] vs.10 [7 to 12] cm H2O; P = 0.002; difference 3 [1 to 5] cm H2O); and 15 mmHg (7 [6 to 9] vs.12 [8 to 15] cm H2O; P < 0.001; difference 4 [2 to 6] cm H2O). The effects of targeted PEEP compared to standard PEEP on respiratory system driving pressure were comparable to the effects on transpulmonary driving pressure, though respiratory system driving pressure was higher than transpulmonary driving pressure at all intraabdominal pressure levels. CONCLUSIONS: Transpulmonary driving pressure rises with an increase in intraabdominal pressure, an effect that can be counterbalanced by targeted PEEP. Future studies have to elucidate which combination of PEEP and intraabdominal pressure is best in term of clinical outcomes.

A multifaceted individualized pneumoperitoneum strategy for laparoscopic colorectal surgery: a multicenter observational feasibility study.

BACKGROUND: While guidelines for laparoscopic abdominal surgery advise using the lowest possible intra-abdominal pressure, commonly a standard pressure is used. We evaluated the feasibility of a predefined multifaceted individualized pneumoperitoneum strategy aiming at the lowest possible intra-abdominal pressure during laparoscopic colorectal surgery. METHODS: Multicenter prospective study in patients scheduled for laparoscopic colorectal surgery. The strategy consisted of ventilation with low tidal volume, a modified lithotomy position, deep neuromuscular blockade, pre-stretching of the abdominal wall, and individualized intra-abdominal pressure titration; the effect was blindly evaluated by the surgeon. The primary endpoint was the proportion of surgical procedures completed at each individualized intra-abdominal pressure level. Secondary endpoints were the respiratory system driving pressure, and the estimated volume of insufflated CO2 gas needed to perform the surgical procedure. RESULTS: Ninety-two patients were enrolled in the study. Fourteen cases were converted to open surgery for reasons not related to the strategy. The intervention was feasible in all patients and well-accepted by all surgeons. In 61 out of 78 patients (78%), surgery was performed and completed at the lowest possible IAP, 8 mmHg. In 17 patients, IAP was raised up to 12 mmHg. The relationship between IAP and driving pressure was almost linear. The mean estimated intra-abdominal CO2 volume at which surgery was performed was 3.2 L. CONCLUSION: A multifaceted individualized pneumoperitoneum strategy during laparoscopic colorectal surgery was feasible and resulted in an adequate working space in most patients at lower intra-abdominal pressure and lower respiratory driving pressure. ClinicalTrials.gov (Trial Identifier: NCT03000465).