Comparison of Changes in Thoracic Fluid Content Between On-Pump and Off-Pump CABG by Use of Electrical Cardiometry

Abstract

To compare the changes in thoracic fluid content, PaO2/FIO2 ratio, plateau pressure, compliance, and postoperative ventilation duration in off-pump coronary artery bypass grafting (OPCAB) and on-pump coronary artery bypass grafting (ONCAB). Prospective observational study. Tertiary-care cardiac center. Over an 18-month period, from December 2019 to May 2021, 111 patients who underwent CAB grafting were enrolled. Group I constituted OPCAB patients and Group II the ONCAB patients. After induction, the authors measured thoracic fluid content (TFC), pulmonary compliance, airway pressures, and the PaO2/FIO2 ratio before skin incision (T1) and after skin closure (T2). The input, output, as well as the duration of postoperative ventilation, also were recorded. At T2, the ONCAB group had a significantly higher change in TFC than the OPCAB group (5.4 ± 1.86 kOhm-1v 4.32 ± 1.84 kOhm-1, p=0.012). The fluid balance was significantly higher in the OPCAB group compared with the ONCAB group (2,159.21 ± 108.73 mL v 1,792.50 ± 151.88 mL, p=0.0001). The decrease in PaO2/FIO2 ratio was significantly lower in the OPCAB group compared with the ONCAB group (-71.34 ± 23.42 v -123.65 ± 36.81, p=0.000). The increase in plateau pressure, decrease in compliance, and postoperative ventilation period were significantly higher in the patients who underwent ONCAB than the patients who underwent OPCAB (p < 0.05). The change in TFC was greater in the ONCAB group, despite the fact that the fluid balance was higher in the OPCAB group. A higher TFC in ONCAB led to lower PaO2/FIO2 ratio, lower compliance, higher plateau pressures, and longer postoperative ventilation.