Severe portal and systemic acidosis during CO2-laparoscopy compared to helium or gasless laparoscopy and laparotomy in a rodent model: an experimental study

Background and aims This experimental study assesses the influence of different gases and insufflation pressures on the portal, central-venous and peripheral-arterial pH during experimental laparoscopy. Methods Firstly, 36 male WAG/Rij rats were randomized into six groups (n = 6) spontaneously breathing during anaesthesia: laparoscopy using carbon dioxide or helium at 6 and 12 mmHg, gasless laparoscopy and laparotomy. 45 and 90 min after setup, blood was sampled from the portal vein, vena cava and the common femoral artery with immediate blood gas analysis. Secondly, 12 animals were mechanically ventilated at physiological arterial pH during 90 min of laparotomy (n = 6) or carbon dioxide laparoscopy at 12 mmHg (n = 6) with respective blood gas analyses. Results Over time, in spontaneously breathing rats, carbon dioxide laparoscopy caused significant insufflation pressure-dependent portal acidosis (pH at 6 mmHg, 6.99 [6.95–7.04] at 45 min and 6.95 [6.94–6.96] at 90 min, pH at 12 mmHg, 6.89 [6.82–6.90] at 45 min and 6.84 [6.81–6.87] at 90 min; p < 0.05) compared to laparotomy (portal pH 7.29 [7.23–7.30] at 45 min and 7.29 [7.20–7.30] at 90 min; p > 0.05). Central-venous and peripheral-arterial acidosis was significant but less severely reduced during carbon dioxide laparoscopy. Laparotomy, helium laparoscopy and gasless laparoscopy showed no comparable acidosis in all vessels. Portal and central-venous acidosis during carbon dioxide laparoscopy at 12 mmHg was not reversible by mechanical hyperventilation maintaining a physiological arterial pH (pH portal 6.85 [6.84–6.90] (p = 0.004), central-venous 6.93 [6.90–6.99] (p = 0.004), peripheral-arterial 7.29 [7.29–7.31] (p = 0.220) at 90 min; Wilcoxon–Mann–Whitney test). Conclusion Carbon dioxide laparoscopy led to insufflation pressure-dependent severe portal and less severe central-venous acidosis not reversible by mechanical hyperventilation.

Effects of Deep Versus Moderate Neuromuscular Blockade in Laparoscopic Gynecologic Surgery on Postoperative Pain and Surgical Conditions: Protocol for a Randomized Controlled Trial (Preprint)

BACKGROUND Postoperative pain, especially shoulder pain, is commonly reported after laparoscopic gynecologic procedures. Some studies suggest that a lower insufflation pressure may reduce the risk of postoperative pain; however, there is no agreement on the optimal pneumoperitoneum pressure during gynecologic laparoscopic surgery or whether lower pressure would lead to clinically significant improvements without increasing operative complications. Questions remain regarding the clinical significance of improvements, safety, and cost-effectiveness of deep neuromuscular blockade with low-pressure pneumoperitoneum. OBJECTIVE The primary objective of this study was to assess the superiority of anesthesia with deep neuromuscular blockade with pneumoperitoneum 8 mm Hg over moderate blockade with pneumoperitoneum 12 mm Hg in terms of overall pain 24 hours after surgery in adult women undergoing pelvic surgery for hysterectomy or benign adnexal diseases. Effects on the intensity and timing of postoperative pain in specific locations, surgeon satisfaction, respiratory and hemodynamic stability, operating times, and direct and indirect costs will be assessed. METHODS In this multicenter, randomized controlled trial with a superiority design, 300 patients will be randomly allocated in the ratio 1:1 to moderate neuromuscular blockade with a target insufflation pressure of 12 mm Hg or deep neuromuscular blockade with a target insufflation pressure of 8 mm Hg, with stratification by type of surgery and clinical center. The patient, the statistician, and the nurse who will assess the primary endpoint will be blinded to the allocation. RESULTS Recruitment to this trial is expected to open in June 2018 and is expected to close in June 2019. CONCLUSIONS This study is designed to confirm the reported benefits of postoperative pain and provide additional data needed to address questions regarding the effects of this intervention on operating theater management and direct and indirect costs. Strengths of this protocol include the large sample size distributed among diverse institutions across the Italian territory and the collection and analysis of data on numerous secondary objectives. Limitations include the possible introduction of bias because the surgeon and anesthesiologist are not blinded to the intervention. REGISTERED REPORT IDENTIFIER RR1-10.2196/9277