Lungs volume status and oxygen transport in patients with coronary artery disease with various types of comorbidity before and after coronary artery bypass grafting

Abstract

Aim. Assessment of lung volume status and oxygen transport system in patients with coronary artery disease (CAD) with different clinical types of comorbidity before and after coronary artery bypass grafting (CABG).Material and methods. The observational controlled study included 66 patients with CAD with a median age of 67 years (95% confidence interval [59; 74]), admitted to the Far Eastern Federal University Hospital for elective CABG. Depending on the prevalence of clinical manifestations of comorbidities, CAD patients were ranked into 3 groups of comorbidity: cardiovascular, respiratory and metabolic. The first of them was represented by a combination of CAD and peripheral artery disease, the second — CAD and chronic obstructive pulmonary disease (COPD),the third — CAD and metabolic syndrome. All patients underwent isolated CABG under cardiopulmonary bypass (CPB). Volume and hemodynamic monitoring was carried out by transpulmonary thermodilution using the Pulsion PiCCO Plus (Germany) technology and the following indices: cardiac function index (CFI), extravascular lung water (EVLW), pulmonary vascular permeability index (PVPI). Pulmonary blood volume and oxygen transport indices were determined: oxygen delivery (DO₂I) and consumption (VO₂I) indices, oxygen-utilization coefficient, and pulmonary shunt fraction (Qs/Qt). The study was carried out in three stages: before the onset of CABG, after its completion and one day after CABG.Results. The analysis of volume and hemodynamic monitoring data demonstrated the heterogeneity of their changes during CABG and one day after with different comorbidity profile. A more noticeable inhibition of the circulatory component of oxygen transport was revealed in patients with COPD, which was illustrated by the lowest CFI (3,2-3,4 ml/min) in relation to other groups of patients. The imbalance of cardio-respiratory interactions in this cohort after withdrawal from cardiopulmonary bypass was manifested by lower DO₂I and VO₂I and a maximum increase in Qs/Qt, exceeding 1,6 times the comparison groups. The respiratory and metabolic comorbidity of CAD was characterized by a significantly larger volume of extravascular lung water due to the higher permeability of the pulmonary vessels, which was documented by EVLW values, which exceeded the upper reference limit by 1,8-2 times and an increase in PVPI. In patients with cardiovascular comorbidity, lung volume violation was less noticeable.Conclusion. A comprehensive analysis of lung volume status and oxygen transport makes it possible to more accurately assess the functional status of patients with CAD, to increase the effectiveness of risk stratification and to prevent possible complications during CABG and in the early postoperative period.