Point-of-Care Ultrasound of Upper Airway Changes During Cardiopulmonary Bypass in Coronary Artery Bypass Grafting: A Randomized Controlled Trial

Background and Objectives: Elevated endotracheal tube (ETT) cuff pressure impairs tracheal mucosal perfusion and may contribute to upper airway soft-tissue changes. During cardiopulmonary bypass (CPB), the cuff usually remains inflated although ventilation is suspended, yet the relevance of cuff pressure management during CPB is unclear. We compared two ETT cuff pressure strategies during CPB (0 vs. 20–30 cmH2O) on point-of-care ultrasound (POCUS) measurements of upper airway soft tissue in patients undergoing coronary artery bypass grafting (CABG). Materials and Methods: In this single-center, prospective, randomized, observer-blinded trial, 76 patients (ASA III–IV, aged 18–80 years) undergoing elective CABG were randomized 1:1 to a 0 cmH2O or 20–30 cmH2O ETT cuff pressure strategy throughout CPB (n = 38 per group). Transesophageal echocardiography (TEE) was not used in any patient. POCUS measurements of lateral pharyngeal wall (LPW) thickness, tongue thickness, parapharyngeal distance, midsagittal tongue area, and tongue width were obtained at four time points (T0–T3). The primary analysis was the omnibus group × time interaction for LPW thickness in a generalized estimating equations (GEE) model; the between-group difference in change from T0 to T2 was a planned supporting contrast. Results: All 76 randomized patients completed the study and were analyzed. The group × time interaction for LPW thickness was significant (p < 0.001); the between-group difference in the increase in LPW thickness from T0 to T2 was 1.50 mm (95% CI 1.27 to 1.73), and 1.00 mm (95% CI 0.82 to 1.18) at postoperative hour 2. Parapharyngeal distance and tongue thickness showed the same pattern. No multiplicity-adjusted between-group difference in LPW thickness was detected at T0 or T1, and a sensitivity analysis using the pre-intervention time point (T1) as baseline gave consistent results (T2 vs. T1: 1.43 mm, 95% CI 1.30 to 1.57). In an exploratory, unadjusted secondary analysis, difficult extubation occurred in 0/38 vs. 7/38 patients (absolute risk difference 18.4 percentage points, 95% CI 5.4 to 33.4; p = 0.012). Conclusions: Complete cuff deflation during CPB was associated with smaller ultrasonographic upper airway soft-tissue changes after CPB. The trial was not powered for clinical outcomes; the lower frequency of difficult extubation is hypothesis-generating, and these data do not support a change in routine practice before confirmation in trials with patient-centered endpoints.