Comparison Of Preoperative And Postoperative Hemodynamic Variability In Obstructive Sleep Apnea Vs Non-Obstructive Sleep Patients: A Prospective Cohort Study

Abstract

Background: Obstructive Sleep Apnea (OSA) is a prevalent condition involving periodic closure of the airway specifically upper airway during sleep, resulting in hypoxemia, sympathetic excitation, and autonomic dysfunction. Such changes can be detrimental for the cardiovascular system during surgery. Nevertheless, studies comparing intraoperative variability of the hemodynamics between OSA patients and patients without OSA are sparse.

Aim: To compare heart rate, blood pressure, and oxygen saturation variability both preoperatively and postoperatively among OSA and non-OSA patients going through elective non-cardiac surgeries under general anesthesia.

Methodology: In this prospective observational study, 118 adult participants undergoing elective non-cardiac surgery were enrolled. The risk of OSA was determined with STOP-BANG criteria and stratified into low, moderate, and high-risk participants. Data on demographic characteristics, comorbid conditions, and American Society of Anesthesiologists (ASA) classification were noted. Heart rate, systolic, and diastolic blood pressure, and SpO₂ were taken before surgery and after surgery. Three time points of postoperative changes were evaluated using repeated measures analysis of variance. The independent sample t-test and effect size estimation were done for OSA vs. non-OSA groups.

Results: The Mean age of subjects was 45.74 ± 11.65 years with almost an equal proportion of gender distribution. Most patients had ASA II category (66.1%), with hypertension being the most frequent co-morbid condition in 49.2% patients. Patients at higher risk for OSA based on STOP-BANG score constituted 43.2% in our study. Prior to surgery, OSA patients showed statistically higher values of heart rate (p<0.001), systolic blood pressure (p=0.003), and diastolic blood pressure (p=0.001) compared to non-OSA patients, whereas preoperative oxygen saturation value was not statistically significant among two groups. After surgery, differences between both groups were seen for heart rate and diastolic blood pressure measurements at later time intervals (T2, T3), whereas systolic blood pressure and SpO2 were statistically comparable in two groups.

Conclusion: Patients with OSA exhibit a higher degree of pre-existing cardiovascular pathology, as shown by an elevated resting heart rate and blood pressure, which play a role in producing selective postoperative variations in the cardiovascular system, primarily the heart rate and diastolic blood pressure. It should be noted that overall perioperative cardiovascular variability does not differ much between patients with OSA and those without OSA.