Xenon may improve gas exchange, during general anesthesia in morbidly obese patients. This study compared the effect of xenon-remifentanil (XR) with sevoflurane-remifentanil (SR) anesthesia on a PaO2/FiO2 ratio in morbidly obese patients. In this prospective, randomized, partially blinded, controlled trial — 20 adult, morbidly obese patients scheduled for roux-en-Y laparoscopic gastric bypass were randomly recruited. All intraoperative continuous variables were recorded every 3 min. Arterial blood gas analysis was performed in the preoperative assessment, at 15 min after the induction of anesthesia and every 60 min during surgery. All patients received remifentanil continuous infusion after intubation, starting with 0.25 mcg/kg/min ideal body weight (IBW) and cisatracurium 0.02 mg/kg IBW every 40 min titrated to clinical needs. Xe administration started after accurate patient denitrogenation; midazolam 0.05 mg/kg IBW was given in order to keep A-line ARX index (AAI) < 30 for the time, 7 to 10 min, occurring to reach 40% FeXe in closed circuit. In SR group, hypnosis was maintained with sevoflurane 1 MAC in a mixture of oxygen-air.
At 15 min after the induction of anesthesia, the two groups in PaO2- FiO2 ratio displayed no differences. However, in XR group, PaO2-FiO2 ratio was significantly higher after 60 and 120 min. Heart rate was significantly lower in XR group, but systolic pressure was significantly lower in SR group. Plateau pressure was significantly higher in XR group, and overall remifentanil consumption was significantly lower. The eyes opening and the extubation time were significantly shorter in XR group, and morphine consumption after 72 hours was significantly lower. PONV was more common in XR group, and only nausea was noticed. Hypotension occurred rarely, but more frequently in SR group.
The “high-density effect” of the inhaled mixture, and its organoprotective and preconditioning effects, may be related to the improvement of PaO2/FiO2 ratio. Recovery times recorded after xenon anesthesia were faster, according to the blood-gas coefficient of the molecule. Xenon anesthesia was characterized by a significantly higher arterial systolic pressure and a minimal variation from preoperative baseline. Heart rate was lower; bradycardia, hypertension, and incidence of postoperative nausea were more evident; and airway pressure was significantly and constantly increased.
Important Findings: The authors showed xenon anesthesia to be associated with improved arterial oxygenation and cardiovascular stability in morbidly obese patients.
