Background: Guidelines do not provide clear recommendations with regard to the use of low intra-abdominal pressure (IAP) during laparoscopic surgery. The aim of this meta-analysis is to assess the influence of low versus standard IAP during laparoscopic surgery on the key-outcomes in perioperative medicine as defined by the StEP-COMPAC consensus group. Materials and methods: We searched the Cochrane Library, PubMed, and EMBASE for randomized controlled trials comparing low IAP (<10 mmHg) with standard IAP (10 mmHg or higher) during laparoscopic surgery without time, language, or blinding restrictions. According to the PRISMA guidelines, two review authors independently identified trials and extracted data. Risk ratio (RR), and mean difference (MD), with 95% CIs were calculated using random-effects models with RevMan5. Main outcomes were based on StEP-COMPAC recommendations, and included postoperative complications, postoperative pain, postoperative nausea and vomiting (PONV) scores, and length of hospital stay. Results: Eighty-five studies in a wide range of laparoscopic procedures (7349 patients) were included in this meta-analysis. The available evidence indicates that the use of low IAP (<10 mmHg) leads to a lower incidence of mild (Clavien–Dindo grade 1–2) postoperative complications (RR=0.68, 95% CI: 0.53–0.86), lower pain scores (MD=−0.68, 95% CI: −0.82 to 0.54) and PONV incidence (RR=0.67, 95% CI: 0.51–0.88), and a reduced length of hospital stay (MD=−0.29, 95% CI: −0.46 to 0.11). Low IAP did not increase the risk of intraoperative complications (RR=1.15, 95% CI: 0.77–1.73). Conclusions: Given the established safety and the reduced incidence of mild postoperative complications, lower pain scores, reduced incidence of PONV, and shorter length of stay, the available evidence supports a moderate to strong recommendation (1a level of evidence) in favor of low IAP during laparoscopic surgery.

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. Editor’s Perspective: What We Already Know about This Topic: What This Article Tells Us That Is New:

Background and objectives In the context of opioid-sparing perioperative management, there is still little evidence from randomized controlled trials regarding the effectiveness of interfascial thoracic blocks. This study hypothesizes that receiving a serratus plane block reduces opioid requirements, pain scores, and rescue medication needs. Methods This double-blind, randomized controlled study was conducted on 60 adult females undergoing oncologic breast surgery. After general anesthesia, patients were randomly allocated to either conventional analgesia (control group, n=30) or single-injection serratus block with L-bupivacaine 0.25% 30mL (study group, n=30). First 24-hour total morphine consumption (primary outcome), pain scores at 1, 3, 6, 12, and 24 hours, time-to-first opioid rescue analgesia, and adverse effects were recorded. Results Median 24 hours’ opioid dose was greater in the control group (median difference 9 mg (95% CI 4 to 14.5 mg); p<0.001). Proportional odds model showed that the study group has a lower probability of receiving opioid drugs (OR=0.26 (95% CI 0.10 to 0.68); p<0.001), while mastectomies have a higher probability of receiving them (OR=4.11 (95% CI 1.25 to 13.58); p=0.002). Pain scores in the study group were significantly lower throughout the follow-up period (p<0.001). Control group subjects needed earlier morphine rescue and had a higher risk of rescue dose requirement (p=0.002). Conclusions Interfascial serratus plane block reduces opioid requirements and is associated with better pain scores and lower and later rescue analgesia needs in the first 24 hours, compared with conventional intravenous analgesia, in breast surgery. Trial registration number NCT02905149.

Background: It is uncertain whether the association of the intraoperative driving pressure (ΔP) with postoperative pulmonary complications (PPCs) depends on the surgical approach during abdominal surgery. Our primary objective was to determine and compare the association of time–weighted average ΔP (ΔP_TW) with PPCs. We also tested the association of ΔP_TW with intraoperative adverse events. Methods: Posthoc retrospective propensity score–weighted cohort analysis of patients undergoing open or closed abdominal surgery in the ‘Local ASsessment of Ventilatory management during General Anaesthesia for Surgery’ (LAS VEGAS) study, that included patients in 146 hospitals across 29 countries. The primary endpoint was a composite of PPCs. The secondary endpoint was a composite of intraoperative adverse events. Results: The analysis included 1128 and 906 patients undergoing open or closed abdominal surgery, respectively. The PPC rate was 5%. ΔP was lower in open abdominal surgery patients, but ΔP_TW was not different between groups. The association of ΔP_TW with PPCs was significant in both groups and had a higher risk ratio in closed compared to open abdominal surgery patients (1.11 [95%CI 1.10 to 1.20], P < 0.001 versus 1.05 [95%CI 1.05 to 1.05], P < 0.001; risk difference 0.05 [95%CI 0.04 to 0.06], P < 0.001). The association of ΔP_TW with intraoperative adverse events was also significant in both groups but had higher odds ratio in closed compared to open abdominal surgery patients (1.13 [95%CI 1.12– to 1.14], P < 0.001 versus 1.07 [95%CI 1.05 to 1.10], P < 0.001; risk difference 0.05 [95%CI 0.030.07], P < 0.001). Conclusions: ΔP is associated with PPC and intraoperative adverse events in abdominal surgery, both in open and closed abdominal surgery. Trial registration: LAS VEGAS was registered at clinicaltrials.gov (trial identifier NCT01601223).

Background: The influence of high positive end-expiratory pressure (PEEP) with recruitment maneuvers on the occurrence of postoperative pulmonary complications after surgery is still not definitively established. Bayesian analysis can help to gain further insights from the available data and provide a probabilistic framework that is easier to interpret. The objective was to estimate the posterior probability that the use of high PEEP with recruitment maneuvers is associated with reduced postoperative pulmonary complications in patients with intermediate-to-high risk under neutral, pessimistic, and optimistic expectations regarding the treatment effect. Methods: Multilevel Bayesian logistic regression analysis was performed on individual patient data from three randomized clinical trials carried out on surgical patients at intermediate to high risk for postoperative pulmonary complications. The main outcome was the occurrence of postoperative pulmonary complications in the early postoperative period. This study examined the effect of high PEEP with recruitment maneuvers versus low PEEP ventilation. Priors were chosen to reflect neutral, pessimistic, and optimistic expectations of the treatment effect. Results: Using a neutral, pessimistic, or optimistic prior, the posterior mean odds ratio for high PEEP with recruitment maneuvers compared to low PEEP was 0.85 (95% credible interval, 0.71 to 1.02), 0.87 (0.72 to 1.04), and 0.86 (0.71 to 1.02), respectively. Regardless of prior beliefs, the posterior probability of experiencing a beneficial effect exceeded 90%. Subgroup analysis indicated a more pronounced effect in patients who underwent laparoscopy (odds ratio, 0.67 [0.50 to 0.87]) and those at high risk for postoperative pulmonary complications (odds ratio, 0.80 [0.53 to 1.13]). Sensitivity analysis, considering severe postoperative pulmonary complications only or applying a different heterogeneity prior, yielded consistent results. Conclusions: High PEEP with recruitment maneuvers demonstrated a moderate reduction in the probability of postoperative pulmonary complication occurrence, with a high posterior probability of benefit observed consistently across various prior beliefs, particularly among patients who underwent laparoscopy.