Elevated pulmonary artery pressures are associated with longer duration of intubation following open heart surgery
Background: The distinct differences in pulmonary circulatory loading between various cardiac lesions affect their postoperative outcomes. This study investigates hemodynamic and CPB factors affecting time to extubation in patients undergoing CABG and mitral valve replacements (MVR). Methods: After the study protocol was approved by the IRB, we studied 25 adult patients (15 CABG and 10 MVR) prospectively. Patient selection criteria included EF ≥45% and absence of additional valvular lesions or significant pulmonary, renal or hepatic disease. CABG patients had no mitral regurgitation and MVR patients had moderate to severe regurgitation. Measurements were collected under mechanical ventilation before and 1, 2, 4, and 6 hours after CPB. The outcome variable was time to extubation. Predictive variables included: i) patient characteristics (age, BSA), ii) hemodynamic profiles (HR, MAP, CO, PA pressure), iii) CPB elements (duration of CPB, cooling temp, total cardioplegia volume, iv) IV fluid intake (in OR and ICU), and v) oxygenation (CaO2, PaO2, PaO2/ FiO2) and ventilation (PaCO2) indices. Results: Of all hemodynamic factors studied, only PA pressures were correlated to time to extubation. When stratified by type of surgery, this positive correlation was more significant in the CABG group (table 1). Whereas both PA pressures and time to extubation were not correlated to oxygenation and ventilation, increase in total OR fluid intake was associated with increase in PA pressure (correlation coefficient = 0.6, p value< 0.001) and longer time to extubation in CABG procedures. Longer intubation times were also associated with older age and smaller BSA in both procedures. Conclusions: PA pressures may be predictive of postoperative intubation time following open heart surgery. Evidence of an association with prolonged time to extubation warrants for careful iv fluid administration in the OR. The role of perioperative ischemia in CABG procedures needs to be elucidated in further studies. Clinical Implications: Correlation Coefficient 1 hr post- CPB 0.9 (p<.0001) 2 hr post-CPB 0.9 (p<.0001) 4 hr post-CPB 0.8 (p<.0001) 6 hr post-CPB 0.6 (p<.04) Table 1. Relationship between systolic PA pressures and time to extubation in CABG procedures.
Afifi, MS; Grecu, L; Janaby, M
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