Influence of passive leg elevation on the right ventricular function in anaesthetized coronary patients

Abstract

Introduction: The aim of the present study was to evaluate the haemodynamic effects of passive leg elevation on the right ventricular function in two groups of patients, one with a normal right ventricular ejection fraction (RVEF) and one with a reduced RVEF. Methods: Twenty coronary patients undergoing elective coronary artery bypass grafting surgery were studied by a RVEF pulmonary artery catheter. The haemodynamic data reported were collected before the induction of anaesthesia (time point 1), just before (time point 2) and 1 min (time point 3) after the legs were simultaneously raised at 60°, and 1 min after the legs were lowered (time point 4). The patients were divided into two groups: group A, with preinduction RVEF > 45%; and group B, with preinduction RVEF < 40%. Results: In group A (n=10), at time point 3 compared with time point 2, the heart rate significantly decreased (from 75±10 to 66±7 beats/min). The right ventricular end diastolic volume index (from 105±17 to 133±29 ml/m2), the right ventricular end systolic volume index (from 61±13 to 77±24 ml/m2), the systolic systemic arterial/right ventricular pressure gradient (from 93±24 to 113±22 mmHg) and the diastolic systemic arterial/right ventricular pressure gradient (from 58±11 to 66±12 mmHg) significantly increased. Also in group A, the cardiac index did not significantly increase (from 3.28±0.6 to 3.62±0.6 l/min/m2), the RVEF was unchanged, and the right ventricular end diastolic volume/pressure ratio (RVED V/P) did not significantly decrease (from 48±26 to 37±13 ml/mmHg). In group B (n=6) at the same time, the heart rate (from 72±15 to 66±12 beats/min), the right ventricular end diastolic volume index (from 171±50 to 142±32 ml/m2) and the RVED V/P (from 71±24 to 39±7 ml/mmHg) significantly decreased. The cardiac index and the diastolic systemic arterial/right ventricular pressure gradient were unchanged in group B, while the RVEF and the systolic systemic arterial/right ventricular pressure gradient did not significantly increase, and the right ventricular end-systolic volume index did not significantly decrease. All results are expressed as mean±standard deviation. Conclusions: We conclude that passive leg elevation caused a worse condition in the right ventricle of group B because, with stable values of cardiac index, of systolic systemic arterial/right ventricular pressure gradient and of diastolic systemic arterial/right ventricular pressure gradient (which supply oxygen), the RVED V/P (to which oxygen consumption is inversely related) markedly decreased. This is as opposed to group A, where the cardiac index, the systolic systemic arterial/right ventricular pressure gradient and the diastolic systemic arterial/right ventricular pressure gradient increased, and the RVED V/P slightly decreased. Passive leg elevation must therefore be performed cautiously in coronary patients with a reduced RVEF.