CARDIOVASCULAR JOURNAL OF AFRICA • Volume 35, No 3, September – October 2024 AFRICA 175 and secondary outcomes, such as 30-day mortality rate, and incidence of re-intubation, postoperative stroke and renal failure. However, in this study, an early extubation protocol did not significantly reduce the rate of patients extubated after 12 hours. In current studies, the variables affecting early extubation have been examined and various findings have been obtained. Nguyen et al.8 stated that male patients and those who had isolated valve surgery with a BMI > 30 kg/m2 could be extubated earlier. Aksoy et al.10 observed that the duration of ventilation was prolonged in female patients with long CPB duration and high leukocyte and lactate values. Although the female gender was observed as a risk factor in both studies, the findings obtained in terms of age and BMI are inconsistent. In another study examining risk factors, age, BMI, COPD, DM, albumin level, isolated aortic valve replacement, and multiple surgeries affected extubation time.9 In this study, Subramaniam et al.,9 contrary to Nguyen et al.,8 stated that female gender was not a risk factor. Additionally, an increase in BMI (> 30 kg/m2) facilitated early extubation for Nguyen et al.,8 while Subramaniam et al.9 argued that an increase in BMI made early extubation difficult. In our study, age, gender, BMI and presence of co-morbidities did not differ between the groups. Among the intra-operative variables, as in the study by Aksoy et al.,10 we observed longer CPB duration in those who were extubated late. Another similarity is that Aksoy et al.10 showed that increased lactate levels cause delayed extubation. However, these researchers did not specify the lactate sampling times. In our study, a significant increase was observed in all serial serum lactate measurements (except L0 and L1) of patients who were extubated late. Studies have shown that serum lactate levels are an independent risk factor in predicting morbidity and mortality in cardiac surgery. Hajjar et al.16 concluded that 10% of the patients they examined developed major complications and that lactate, age and left ventricular ejection fraction < 40% were the main predictors. Similarly, Duval et al.17 observed that an increase in intra-operative lactate level was important for determining morbidity. However, they concluded that only difference in lactate level (ΔL) > 1 mmol/l for 30-day mortality was an independent factor. Reviewing 779 elective cardiac surgeries, Govender et al.18 showed that increased intra-operative lactate level was associated with mortality, ICU length of stay, and the risk of developing postoperative renal failure. Michaud et al.13 reported that a serum lactate level of > 4 mmol/l at admission to the ICU prolonged the mechanical ventilation time. The increase in lactate levels during cardiac surgery has been associated with various factors. In a retrospective study of 917 patients who had undergone mitral valve surgery, Evans et al.19 determined that factors that increased the lactate level at admission to the ICU were gender (male patient), long duration of CPB and blood transfusion. However, in patients with a successful fast-track management protocol, lactate levels were observed to decrease significantly at admission to the recovery unit.20 In the same study, the baseline excess simultaneously decreased significantly. In our study, the serum lactate levels increased significantly less in patients who were extubated early. Prolongation of CPB duration and ACCT were the main reasons for the increase in serum lactate levels in both groups. However, we observed that lactate levels were at lower threshold values, such as 1.7–2.2 mmol/l in patients with a long intubation time, unlike in the study by Michaud et al.13 Limitations Our research has several limitations. First, our research was designed retrospectively. Second, only patients who had undergone isolated CABG surgery were included in the study. Third, the study period covered patients for one year. The last limitation was that pre- and post-extubation blood gas analysis was not included. The main reason for this was the difficulty in standardisation of timing of samples taken before and after extubation. These four limiting factors led to the small number of patients included in the study. Conclusion We conclude that intra-operative serial serum lactate levels, particularly ΔL, are important in predicting early extubation after isolated CABG surgery. Extended CPB and ACCT can prolong the mechanical ventilation time. References 1. Grocott HP. 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