Individual and combined effects of chemical and mechanical power on postoperative pulmonary complications: a secondary analysis of the REPEAT study

Introduction: Intra-operative supplemental oxygen and mechanical ventilation expose the lungs to potentially injurious energy. This can be quantified as 'chemical power' and 'mechanical power', respectively. In this study, we sought to determine if intra-operative chemical and mechanical power, individually and/or in combination, are associated with postoperative pulmonary complications. Methods: Using an individual patient data analysis of three randomised clinical trials of intra-operative ventilation, we summarised intra-operative chemical and mechanical power using time-weighted averages. We evaluated the association between intra-operative chemical and mechanical power and a collapsed composite of postoperative pulmonary complications using multivariable logistic regression to estimate the odds ratios related to the effect of 1 J.min-1 increase in chemical or mechanical power with adjustment for demographic and intra-operative characteristics. We also included an interaction term to assess for potential synergistic effects of chemical and mechanical power on postoperative pulmonary complications. Results: Of 3837 patients recruited to three individual trials, 2492 with full datasets were included in the analysis. Intra-operative time-weighted average (SD) chemical power was 10.2 (3.9) J.min-1 and mechanical power was 10.5 (4.4) J.min-1. An increase of 1 J.min-1 in chemical power was associated with 8% higher odds of postoperative pulmonary complications (OR 1.08, 95%CI 1.05-1.10, p < 0.001), while the same increase in mechanical power raised odds by 5% (OR 1.05, 95%CI 1.02-1.08, p = 0.003). We did not find evidence of a significant interaction between chemical and mechanical power (p = 0.40), suggestive of an additive rather than synergistic effect on postoperative pulmonary complications. Discussion: Both chemical and mechanical power are independently associated with postoperative pulmonary complications. Further work is required to determine causality

Efficacy and Safety of Prothrombin Complex Concentrates in Liver Transplantation: Evidence from Observational Studies

The risk/benefit ratio of using prothrombin complex concentrates (PCCs) to correct coagulation defects in patients with end-stage liver disease is still unclear. The primary aim of this review was to assess the clinical effectiveness of PCCs in reducing transfusion requirements in patients undergoing liver transplantation (LT). This systematic review of non-randomized clinical trials was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. The protocol was previously registered (PROSPERO:CRD42022357627). The primary outcome was the mean number of transfused units for each blood product, including red blood cells (RBCs), fresh frozen plasma, platelets, and cryoprecipitate. Secondary outcomes included the incidence of arterial thrombosis, acute kidney injury, and haemodialysis, and hospital and intensive care unit length of stay. There were 638 patients from 4 studies considered for meta-analysis. PCC use did not affect blood product transfusions. Sensitivity analysis, including only four-factor PCC, showed a significant reduction of RBC effect size (MD: 2.06; 95%CI: 1.27–2.84) with no true heterogeneity. No significant differences in secondary outcomes were detected. Preliminary evidence indicated a lack of PCC efficacy in reducing blood product transfusions during LT, but further investigation is needed. In particular, future studies should be tailored to establish if LT patients will likely benefit from four-factor PCC therapy

Perioperative management

Perioperative Managemen

Suction catheter guided insertion of ProSeal laryngeal mask airway: Experience by untrained physicians

BACKGROUND: The use of suction catheter (SC) has been shown to improve success rate during ProSeal laryngeal mask airway (PLMA) insertion in expert users. AIMS: The aim of this study was to compare insertion of PLMA performed by untrained physicians using a SC or the digital technique (DT) in anaesthetised non-paralysed patients. METHODS: In this prospective randomised double-blind study, conducted in the operating setting, 254 patients (American Society of Anaesthesiologists I-II, aged 18-65 years), undergoing minor surgery were enrolled. Exclusion criteria were body mass index >35 kg/m(2), laryngeal or oesophageal varices, risk of aspiration or difficult face mask ventilation either referred or suspected (Langeron's criteria 652) and modified Mallampati classification score >2. Participants were randomly allocated to one of the two groups in which PLMA was inserted using DT (DT-group) or SC (SC-group). STATISTICAL ANALYSIS: Chi-square test with Yates' correction, Mann-Whitney U-test or Student's t-test were carried-out as appropriate. RESULTS: The final insertion success rate was greater in SC-groupcompared with DT-group 90.1% (n = 109) versus 74.4% (n = 99) respectively (P = 0.002). Mean airway leak pressure was higher in SC-group compared to DT-group (23.7 \ub1 3.9 vs. 21.4 \ub1 3.2 respectively; (P = 0.001). There were no differences in insertion time, post-operative airway morbidity and complications. CONCLUSION: The findings of this study suggest that SC-technique improves the success rate of PLMA insertion by untrained physicians