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

OBJECTIVES: 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). DESIGN: Prospective observational study. SETTING: Tertiary-care cardiac center. PARTICIPANTS: 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. INTERVENTIONS: 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. RESULTS: 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). CONCLUSION: 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.

Balancing a single-ventricle circulation: 'physiology to therapy'.

The parallel supply of the pulmonary and systemic circuits complicates the management of single-ventricle lesions. Achieving a balance between the two limbs of the circulation forms the basis of optimizing the systemic oxygen delivery, with the oxygen availability being highly sensitive to alterations in pulmonary/systemic blood flow ratio (Q p/Q s). The identification of a 'balanced' circulation is challenging wherein various parameters should be evaluated in close conjunction with each other. The prompt identification of circulatory maldistribution should be backed up with a sound management strategy aimed at attaining an equitable systemic and pulmonary perfusion. Any degree of ventricular dysfunction compromises the total output (Q p + Q s) supplying the two circuits explaining the role of inodilators in improving the myocardial performance in addition to lowering the systemic vascular resistance and optimizing Q p/Q s in setting of a single-ventricle physiology. Moreover, the pulmonary circulation is modulated by a multitude of factors intricately linked to the single-ventricle lesion, including anatomical characteristics unique to the underlying lesion (branch pulmonary arterial and venous stenosis), preoperative interventions, associated aortopulmonary and venovenous collaterals, plastic bronchitis, pulmonary arteriovenous fistulae, underlying ventricular dysfunction,, and many others. The article highlights the physiology, diagnosis, therapeutic optimization of a single-ventricle circulation, and the peculiarities pertaining to the pulmonary circulation of the uni-ventricular lesions.