A. Khalid1,2, S. Hakeem1, H. Mallick1, M. Khan1, S. Hashmi1, S. Shahabuddin1 1Aga Khan University Medical College, Cardiothoracic Surgery, Karachi, Sindh, Pakistan 2North Shore University And Long Island Jewish Medical Center, Surgery, Manhasset, NY, USA
Introduction:
Open heart surgery is a common procedure for various coronary artery diseases. Despite advancements in surgical techniques, postoperative complications, particularly hypoxemia, remain significant due to the systemic inflammatory response syndrome often seen in cardiac surgery. Hypoxemia can lead to reintubation and is influenced by factors like age, weight, smoking history, and surgery duration. This study aims to determine the prevalence, risk factors, and short-term outcomes of post-open heart surgery hypoxemia in a lower middle-income setting.
Methods:
This retrospective analysis included patients who underwent first-time open-heart surgery in 2020. Data were collected prospectively through a standardized database, excluding redo-cardiac and complex aortic surgeries. Variables were categorized into preoperative, intraoperative, and postoperative stages. Hypoxemia was defined as blood oxygen levels <70 mmHg within 6 hours post-extubation and on discharge from CICU. Statistical analysis included t-tests, chi-squared tests, and logistic regression to identify independent risk factors for hypoxemia.
Results:
Of 619 patients, 73 (11.8%) developed postoperative hypoxemia. Hypoxemic patients were younger (p=0.043), predominantly male (p=0.006), and more likely to have a low ejection fraction (76.7% vs. 20.9%, p<0.001) (Table 1). Urgent/emergent procedures were more common in the hypoxemia group (38.4% vs. 21.1% and 9.6% vs. 6.6%, p=0.002). The hypoxemia group had higher mean pump times (125.1±40.0 vs. 98.01±26.5 minutes, p<0.001) and cross-clamp times (80±33.3 vs. 73.63±22.4 minutes, p=0.034). Postoperatively, hypoxemic patients required prolonged ventilation more frequently (16.4% vs. 2.9%, p<0.001), had lower PO2 levels (44±11.6 vs. 110.26±40.3 mmHg, p<0.001), and higher PCO2 levels (54.3±13.8 vs. 45.91±5.9 mmHg, p<0.001). Outcomes indicated higher morbidity (56.2% vs. 31.1%, p<0.001) and mortality (16.4% vs. 1.1%, p<0.001) in hypoxemic patients. Length of hospital stay was longer for hypoxemic patients (12.9±7.6 vs. 8.4±7.6 days, p<0.001), and readmission rates were higher (9.6% vs. 3.8%, p=0.027). Independent risk factors for postoperative hypoxemia included diabetes (OR=2.52), hypertension (OR=2.62), low ejection fraction (OR=0.94), longer CPB time (OR=1.03), and higher preoperative PaCO2 (OR=1.07).
Conclusion:
Hypoxemia is a significant postoperative complication following open heart surgery, associated with increased morbidity and mortality. This study provides critical insights into the management of hypoxemia in open-heart surgery patients, particularly in lower-middle-income settings.