Effect of Hypoxemia in the Determination of Short-Term Prognosis of Coronary Artery Bypass Graft Patients: A Prospective Study

Respiratory failure and hypoxemia are the known complications of anesthesia and surgery. As a major surgery mainly at advanced ages, the coronary artery bypass graft (CABG) surgery could lead to hypoxemia in the early post-operative phase. Currently, the fraction of partial pressure of arterial oxygen to the fraction of inspired oxygen (PiO2/FiO2) is used to determine the severity of the respiratory assault. This study aimed to find the effect of hypoxemia measured by PaO2/FiO2 at the first hour following CABG in the determination of short-term prognosis of CABG. Being approved by a local ethics committee, this observational cross-sectional study was conducted in 212 patients undergoing CABG on the cardiopulmonary pump, with no concurrent surgery or other cardiac pathologies. Factors like age, sex, weight, height, the duration of pump and cross-clamp, as well as other medical conditions including chronic obstructive pulmonary disease (COPD), diabetes mellitus (DM), opioid use, ejection fraction (EF), and creatinine clearance (CrCl) before the surgery were brought into consideration as possible confounders. The ratio of PiO2/FiO2 in the first hour after the surgery was measured, and its effect on intubation time and intensive care unit (ICU) length of stay was evaluated as the primary outcomes. The t-test and chi-squared were used to compare quantitative and qualitative variables, respectively. The repeated measures ANOVA test was used to compare the means. There was no significant relationship between hypoxemia measured as the ratio of PaO2/FiO2 and the duration of ICU length of stay (P value = 0.220) and the total intubation time (P value = 0.661). Among the qualitative variables, just opium addiction in patients with PaO2/FiO2 > 300 was associated with significantly longer intubation time (P value = 0.016). Furthermore, in the quantitative variables, longer intubation time was associated with higher cross-clamp time (P value = 0.035) in hypoxemia in the range of ARDS patients. Hypoxemia after the CABG surgery is common and does not affect the short-term prognosis of CABG patients.