Reduction in FEV₁ following spinal anesthesia is associated with intraoperative complications: A prospective study

Background and Aims: Although Spinal Anesthesia (SA) remains the technique of choice for many surgeries below the umbilicus, it is associated with multiple intraoperative complications. Sympathetic blockade and Bezold-Jarisch reflex do not fully explain SA-related cardiopulmonary complications. Reduction in FEV₁ has been reported as a predictor of sudden cardiac death. This study aimed to determine the association between reduction in FEV₁ following SA and adverse intraoperative cardiopulmonary complications. Materials and Methods: A prospective study of 48 patients of ASA status I and II with no history of primary cardiopulmonary disease scheduled for elective surgery under SA. Spirometry was performed based on ATS/ERS guidelines before induction and 30 min after induction of SA. FEV₁% predicted was determined using GLI 2012 equations. Participants were grouped into two (∆FEV₁% < 10% and ∆FEV₁% ≥ 10%) based on reductions (∆) in FEV₁% predicted following SA. Logistic regression analyses were used to examine associations between ∆FEV₁% and intraoperative hypoxia, hypotension, bradycardia, and nausea/vomiting, with adjustments for age, gender, and BMI. Results: The mean FEV₁% predicted following SA was lower than the mean FEV₁% predicted before SA (83.42 vs. 95.31, p = 0.001). In a fully adjusted model, ∆FEV₁% ≥ 10% was associated with an increased risk of hypoxia [AOR 13.55; 95% CI, 1.07–171.24, p = 0.044]. The positive associations between ∆FEV₁% ≥ 10% and hypotension [2.02 (0.33–12.46), 0.449], bradycardia [1.10 (0.28–4.25), 0.895] and nausea/vomiting [9.74 (0.52–183.94), 0.129] were not statistically significant. Conclusion: Reduction in FEV₁% predicted following SA was associated with adverse intraoperative outcomes. FEV₁ may play an important role in the association between SA and cardiopulmonary complications.