Factors Associated with Prolonged Mechanical Ventilation in Late Repair of Tetralogy of Fallot

Abstract

Research establishing factors associated with duration of mechanical ventilation after Tetralogy of Fallot repair, is mainly based on population presenting at early infancy. There are fewer reports regarding repair after infancy, during childhood and preadolescence. To compare two groups of late TOF repair based on post-operative invasive mechanical ventilation duration and explore associations with pre-operative clinical markers of severity of right ventricular outflow tract obstruction. A single-center retrospective cohort study based on medical charts review of patients older than 12 months who underwent primary complete TOF repair between 2017 and 2023. Patients younger than 12 months or those who had distinct anatomical variants were excluded. Pre-operative characteristics reflecting the severity of right ventricular outflow tract obstruction were collected, including baseline oxygen saturation, the occurrence of hypercyanotic spells, maximum right ventricular outflow tract pressure gradient. Perioperative variables included repair type, cardiopulmonary bypass and aortic cross-clamp duration, and rates of residual lesions. 280 patients from 27 countries were screened; 181 remained eligible and were significantly older than previously reported. 129 (71%) were extubated early post-operatively, while 52 (29%) had a longer ventilation course. In a multivariate analysis, only baseline oxygen saturation and repair type maintained a significant association with length of mechanical ventilation. In distinctly older patients undergoing TOF repair, those with lower base line saturation undergoing a non-valve preserving repair are more likely to have a longer course of mechanical ventilation. Other clinical markers reflecting the severity of right ventricular outflow tract obstruction were not independently associated with mechanical ventilation duration.

Keywords: Hypercyanotic spells; Invasive mechanical ventilation; Late repair; Right ventricular outflow tract obstruction; Tetralogy of Fallot.