Effect of perioperative sigh ventilation on postoperative hypoxemia and pulmonary complications after on-pump cardiac surgery (E-SIGHT): study protocol for a randomized controlled trial

Abstract

Background: Postoperative hypoxemia and pulmonary complications remain a frequent event after on-pump cardiac surgery and mostly characterized by pulmonary atelectasis. Surfactant dysfunction or hyposecretion happens prior to atelectasis formation, and sigh represents the strongest stimulus for surfactant secretion. The role of sigh breaths added to conventional lung protective ventilation in reducing postoperative hypoxemia and pulmonary complications among cardiac surgery is unknown.

Methods: The perioperative sigh ventilation in cardiac surgery (E-SIGHT) trial is a single-center, two-arm, randomized controlled trial. In total, 192 patients scheduled for elective cardiac surgery with cardiopulmonary bypass (CPB) and aortic cross-clamp will be randomized into one of the two treatment arms. In the experimental group, besides conventional lung protective ventilation, sigh volumes producing plateau pressures of 35 cmH₂O (or 40 cmH₂O for patients with body mass index > 35 kg/m²) delivered once every 6 min from intubation to extubation. In the control group, conventional lung protective ventilation without preplanned recruitment maneuvers is used. Lung protective ventilation (LPV) consists of low tidal volumes (6-8 mL/kg of predicted body weight) and positive end-expiratory pressure (PEEP) setting according to low PEEP/FiO₂ table for acute respiratory distress syndrome (ARDS). The primary endpoint is time-weighted average SpO₂/FiO₂ ratio during the initial post-extubation hour. Main secondary endpoint is the severity of postoperative pulmonary complications (PPCs) computed by postoperative day 7.

Discussion: The E-SIGHT trial will be the first randomized controlled trial to evaluate the impact of perioperative sigh ventilation on the postoperative outcomes after on-pump cardiac surgery. The trial will introduce and assess a novel perioperative ventilation approach to mitigate the risk of postoperative hypoxemia and PPCs in patients undergoing cardiac surgery. Also provide the basis for a future larger trial aiming at verifying the impact of sigh ventilation on postoperative pulmonary complications.

Trial registration: ClinicalTrials.gov NCT06248320. Registered on January 30, 2024. Last updated February 26, 2024.

Keywords: Cardiac surgery; Cardiopulmonary bypass; Mechanical ventilation; Postoperative hypoxemia; Postoperative pulmonary complications; Sigh.

Fig. 1

Consolidated Standards of Reporting Trials (CONSORT) diagram for the E-SIGHT trial. ECMO, extracorporeal membrane oxygenation; IABP, intra-aortic balloon pump; CPAP, continuous positive airway pressure; LPV, lung protective ventilation

Fig. 2

E-SIGHT trial schedule during the study period. HFNC high-flow nasal cannula, ICU intensive care unit, IMV intensive mechanical ventilation, NIV non-invasive ventilation, PaO₂ arterial pressure in oxygen, POD postoperative day, SpO₂ pulse oximetry, FiO₂ inspired oxygen fraction