Antioxidant effect of muscle relaxants (vecuronium, rocuronium) on the rabbit abdominal aortic endothelial damage induced by reactive oxygen species / 대한마취과학회지

BACKGROUND: Muscle relaxants induce vascular smooth muscle relaxation by inducing synthesis of the prostaglandins that influence vasomotor tone. However, the effects of muscle relaxants on endothelial cells and tissues following injury by reactive oxygen species (ROS) are unclear. We tested the effects of the muscle relaxants vecuronium and rocuronium on impaired acetylcholine (ACh)-induced relaxation following induction of ROS in rabbit aorta in vitro. METHODS: Isolated rabbit abdominal aortic ring segments were pretreated with vecuronium or rocuronium at 10(-4), 3 x 10(-4), 10(-3) or 3 x 10(-3) M, with or without inhibitors of Cu/Zn superoxide dismutase (diethyldithiocarbamate; DETCA, 0.8 mM) or catalase (3-amino-1,2,4-triazole; 3AT, 50 mM). All groups of aortic rings were then exposed to ROS generated by electrolysis in the organ bath medium (Krebs-Henseleit solution). The effects of vecuronium and rocuronium on ROS-induced impairment of relaxation induced by ACh (10(-6) M) were assessed. RESULTS: Aortic rings treated with vecuronium or rocuronium at 10(-4), 3 x 10(-4), 10(-3) or 3 x 10(-3) M preserved the capacity for ACh-induced endothelial relaxation following ROS exposure in a dose-dependent manner. Pretreatment with DETCA partially inhibited the protective effects of vecuronium and rocuronium on ACh-induced relaxation (P < 0.001), but pretreatment with 3AT had no effect. CONCLUSIONS: Muscle relaxants protected the endothelium in isolated rabbit abdominal aorta from free-radical injury in a dose-dependent manner. These results suggest that vecuronium and rocuronium may act as superoxide anion scavengers.

Optimal positive end-expiratory pressure during robot-assisted laparoscopic radical prostatectomy / 대한마취과학회지

BACKGROUND: Increased intra-abdominal pressure during laparoscopic surgery causes cephalad displacement of the diaphragm, resulting in the formation of atelectasis, which can be overcome by positive end-expiratory pressure (PEEP). The aim of this prospective study was to investigate the level of optimal PEEP to maintain adequate arterial oxygenation and hemodynamics during robot-assisted laparoscopic radical prostatectomy (RLRP). METHODS: One hundred patients undergoing RLRP were randomly allocated to one of five groups (n = 20) (0, 3, 5, 7 and 10 cmH2O of PEEP). Hemodynamic variables and respiratory parameters were measured at baseline with the patient in the supine position; at 30 min, 1, 2, 3 and 4 h during CO2 insufflation with the patient in the post-Trendelenburg position; and after deflation in the supine position with increasing PEEP. RESULTS: The PaO2 levels and alveolar-arterial difference in oxygen tension (AaDO2) were improved in patients with PEEPs compared with patients in whom PEEP was not used. The application of PEEP (10 cmH2O) resulted in higher PaO2 levels compared to those with lower PEEP levels, but excessive peak airway pressure (PAP) was sometimes observed. The application of a PEEP of 7 cmH2O resulted in similar PaO2 levels without causing excessive PAP. There was a significant difference in central venous pressure between the groups, but there were no significant differences in heart rate, mean arterial pressure or minute ventilation between the groups. CONCLUSIONS: A PEEP of 7 cmH2O is associated with the greater improvement of PaO2 and AaDO2 without causing excessive PAP during RLRP.