Effect of Left Paratracheal Pressure on Cerebral Oxygenation During General Anesthesia

Overview

Left paratracheal pressure (LPP) has been proposed as an alternative to cricoid pressure to reduce the risk of regurgitation during induction of general anesthesia. Previous studies suggest that LPP can effectively compress the esophagus without significantly reducing left carotid blood flow. However, its effect on cerebral oxygenation has not yet been evaluated. The aim of this prospective randomized crossover study is to assess whether application of LPP affects regional cerebral oxygen saturation measured by near-infrared spectroscopy (NIRS) during general anesthesia. Seventy adult patients undergoing elective surgery under general anesthesia with tracheal intubation will be included. After induction of anesthesia and stabilization, cerebral oxygen saturation will be continuously measured under three conditions: no cervical pressure, left paratracheal pressure at 30 N, and cricoid pressure at 30 N. The order of the two pressure maneuvers will be randomized. The primary objective is to determine the change in left regional cerebral oxygen saturation during LPP compared with baseline without cervical pressure.

Pulmonary aspiration of gastric contents remains a potentially serious complication of general anesthesia. Cricoid pressure has traditionally been used during induction of anesthesia to reduce the risk of regurgitation, although its effectiveness and its potential effects on airway management remain debated. Left paratracheal pressure (LPP) has been proposed as an alternative technique based on the frequent left-sided position of the cervical esophagus. Anatomical and clinical studies have suggested that LPP may provide effective esophageal compression while preserving airway management conditions. Previous work from the investigators also showed that application of LPP at 30 N did not significantly decrease left carotid blood flow. However, carotid blood flow is an indirect marker of cerebral perfusion, and the effect of LPP on cerebral oxygenation remains unknown. PARANIRS is a prospective, single-center, randomized, controlled crossover study designed to evaluate the effect of LPP on regional cerebral oxygen saturation during general anesthesia. Each participant will serve as their own control. After induction of general anesthesia, neuromuscular blockade, tracheal intubation, and hemodynamic stabilization, bilateral regional cerebral oxygen saturation will be continuously monitored using near-infrared spectroscopy. Measurements will be obtained during a baseline period without cervical pressure and during application of two cervical pressure maneuvers: left paratracheal pressure at 30 N and cricoid pressure at 30 N. The order of the two cervical pressure maneuvers will be randomized. Each maneuver will be applied for 60 seconds using a calibrated force-measuring device to ensure a constant force of 30 N, with a 60-second washout period between interventions. Hemodynamic and respiratory variables, including mean arterial pressure, heart rate, peripheral oxygen saturation, and end-tidal carbon dioxide, will also be continuously recorded. The study is intended to determine whether LPP produces a clinically relevant change in regional cerebral oxygenation and to compare its physiological effects with those of conventional cricoid pressure.