Background/Objectives: Obstructive sleep apnea is a prevalent, yet often underdiagnosed, condition characterized by recurrent upper airway obstruction during sleep, leading to significant perioperative risks in surgical patients. This systematic review aims to evaluate the incidence and impact of objectively diagnosed obstructive sleep apnea on postoperative outcomes across various surgical specialties—including bariatric, orthopedic, cardiac, and otorhinolaryngologic surgeries—and to assess the effectiveness of preoperative screening and perioperative management strategies. Methods: A comprehensive literature search of PubMed was conducted for studies published between January 2013 and December 2024, following Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Included studies involved adult surgical patients with OSA confirmed by polysomnography or respiratory polygraphy. Studies were assessed for methodological quality using the Oxford Centre for Evidence-Based Medicine Levels of Evidence framework. Results: The findings consistently indicated that obstructive sleep apnea significantly increases the risk of postoperative complications, such as respiratory depression, atrial fibrillation, acute kidney injury, delirium, and prolonged hospital stay. Continuous positive airway pressure therapy demonstrated a protective effect in bariatric and cardiac surgeries, though its effectiveness in orthopedic and otorhinolaryngologic contexts was inconsistent, largely due to adherence variability and limited implementation. Preoperative screening tools such as the STOP-BANG questionnaire were widely used, but their utility depended on integration with confirmatory diagnostics. Conclusions: Obstructive sleep apnea represents a significant, modifiable risk factor in surgical populations. Preoperative identification and risk-adapted perioperative management, including CPAP therapy and multimodal analgesia, may substantially reduce postoperative morbidity. However, further randomized trials and cost-effectiveness studies are needed to optimize care pathways and ensure consistent implementation across surgical disciplines.

Background: The perioperative impact of calcium and vitamin D on left ventricular (LV) performance during major cardiac surgery remains unexplored. We aimed to assess the relation of calcium and vitamin D measured at different time points with the LV ejection fraction (EF), and to investigate whether changes in EF correlate with postoperative outcomes. Methods: We enrolled 83 patients, in whom ionized calcium was measured before, during, and after surgery (until discharge), vitamin D preoperatively, and EF pre- and postoperatively at 24 h. The postoperative outcomes were cardiopulmonary bypass (CPB) time, aortic cross-clamp time, mechanical ventilation time, vasoactive inotropic score (VIS) (intraoperative, day 0, day 1), and ICU stay time. Results: The mean age was 64.9 ± 8.5 years, with 21 of the patients (25%) having an EF < 50%. The median change from preoperative to postoperative EF was −2.0 (−10.0–0.0) % (p < 0.001). At the baseline, the EF < 50% group had significantly lower preoperative vitamin D levels than the EF ≥ 50% group (p = 0.048). The calcium trend did not differ across the groups. Preoperative EF was significantly associated with CPB time (r = 0.22, p = 0.044) and aortic cross-clamp time (r = 0.24, p = 0.031). Postoperative EF was significantly and inversely associated with intraoperative VIS (r = −0.28, p = 0.009), VIS day 0 (r = −0.25, p = 0.020), VIS day 1 (r = −0.23, p = 0.036), and ICU length of stay (r = −0.22, p = 0.047). Finally, the change in ejection fraction was significantly and inversely associated with CPB time (r = −0.23, p = 0.037), aortic cross-clamp time (r = −0.22, p = 0.044), intraoperative VIS (r = −0.42, p < 0.001), VIS day 0 (r = −0.25, p = 0.024), mechanical ventilation time (r = −0.22, p = 0.047), and ICU length of stay (r = −0.23, p = 0.039). Conclusions: The fluctuations in perioperative ionized calcium levels were not associated with the evolution of LVEF, although preoperative vitamin D levels may affect those with low EF. Correspondingly, a reduced EF significantly impacted all the studied postoperative outcomes. Further investigation into biomarkers affecting cardiac inotropic function is warranted to better understand their significance.