Echocardiographic and Hemodynamic Evaluation of Cardiovascular Performance during Laparoscopy of Morbidly Obese Patients

Background: The effects of morbid obesity, pneumoperitoneum (PP) and body position on cardiac function during laparoscopy were studied. Methods: Transesophageal echocardiography (TEE) was performed on 10 obese patients (body mass index, BMI, 48.1±1.8 kg/m²) and 10 normal weight patients (BMI = 22.6±0.8 kg/m²) in supine, Trendelenburg and reverse Trendelenburg positions before and after PP. Left ventricular end-systolic wall stress (LVESWS) was calculated from invasive blood pressure (BP) values and LV dimensions obtained by TEE. Diastolic filling was assessed by mitral valve and pulmonary vein flow velocities. Results: LVESWS was higher in obese patients both at baseline (46.0±4.0x10³dyn/cm ²) and with PP (69.3±8.2x10³ dyn/cm²), than normal weight subjects (31.9±3.7x10³ dyn/cm² and 45.7±5.9x10³ dyn/cm²; P<0.05 obese vs normal weight patients at baseline). Systolic BP was not different between groups at baseline (normal weight 111±4 mmHg, obese 119±3 mmHg), but increased significantly with PP only in obese patients (normal weight 129±6 mmHg, obese 157±8 mmHg; P<0.05). Postural changes during PP had no impact on cardiac function in either obese or normal weight subjects. Conclusions: Anesthetized obese patients undergoing laparoscopy have higher LVESWS before pneumoperitoneum (due to increased end-systolic left ventricular dimensions) and during pneumoperitoneum (due to more pronounced increases in blood pressure). Since LVESWS is a determinant of myocardial oxygen demand, more aggressive control of blood pressure (ventricular afterload) in MO patients may be warranted to optimize the myocardial oxygen requirements.