Effect of Left Paratracheal Pressure on Cerebral Oxygenation During General Anesthesia

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.

Inclusion criteria

• Age ≥18 years
• Scheduled for elective surgery requiring general anesthesia with orotracheal intubation
• American Society of Anesthesiologists (ASA) physical status I to III
• Ability to understand the study information
• Written informed consent obtained before study procedures

Exclusion criteria

• Refusal to participate
• Known or suspected pregnancy
• Emergency surgery
• Inability to provide informed consent
• History of stroke or transient ischemic attack within the previous 6 months
• Known severe carotid artery stenosis (>70%) or previous carotid surgery
• Known intracranial hypertension
• Cervical malformation or previous cervical surgery preventing correct application of left paratracheal pressure or cricoid pressure
• Technical inability to correctly position the NIRS sensors
• Any condition considered by the investigator to be incompatible with study participation