Pulmonary Reserve and Respiratory Recovery After Cardiac Surgery: Insights from Preoperative Spirometric Phenotyping

Background: Postoperative respiratory dysfunction remains a frequent complication after cardiac surgery, yet the influence of preoperative pulmonary reserve on postoperative respiratory recovery remains incompletely understood. We investigated whether preoperative spirometric phenotype was associated with postoperative ventilatory burden following cardiac surgery. Methods: We performed a secondary analysis of a prospective cohort of adults undergoing elective cardiac surgery with cardiopulmonary bypass. Preoperative spirometry was used to classify patients as having normal spirometry, a restrictive spirometric pattern, or an obstructive spirometric pattern according to ERS/ATS recommendations. The primary endpoint was VBI, a study-specific, unweighted composite defined as the cumulative duration of IPPV, SIMV, invasive CPAP, and post-extubation CPAP/AIRVO support. Univariable and multivariable linear regression analyses were performed to evaluate variables associated with postoperative VBI. Results: A total of 129 patients were included. Preoperative spirometry was normal in 82 patients (63.6%), demonstrated a restrictive spirometric pattern in 20 (15.5%), and an obstructive spirometric pattern in 25 (19.4%). VBI did not differ significantly among spirometric phenotypes (p = 0.443). In the multivariable analysis, preoperative spirometric phenotype was not significantly associated with VBI. Older age was associated with higher VBI (β = 0.0095, p = 0.015), whereas higher left ventricular ejection fraction was associated with lower VBI (β = −0.0161, p = 0.032). Exploratory analyses demonstrated a numerical tendency toward longer invasive respiratory-support duration among patients with a moderate restrictive spirometric pattern. Conclusions: Broad preoperative spirometric phenotype was not significantly associated with cumulative postoperative respiratory-support burden. Exploratory findings should be regarded as hypothesis-generating. Larger prospective studies are needed to determine whether restrictive spirometric abnormalities are associated with delayed liberation from invasive mechanical ventilation.