Estimation of cardiac preload changes by systolic pressure variation in pigs undergoing pneumoperitoneum

Background: Variations in systolic pressure arterial waveform (SPV) and its component have been shown to be a reasonable indicator of left ventricular preload. Creation of a pneumoperitoneum (PMOP) by insufflation of CO2 incr eases intrathoracic pressure, leading to overestimation of preload as asses sed by pressure methods. The purpose of this study was to compare SPV with other standard methods in anaesthetized pigs. Methods: We measured SPV and its DeltaDown component (Delta Down), pulmonar y artery occlusion pressure (PAOP) and left ventricular short-axis cross-se ctional area using transthoracic echocardiography (TTE) in 7 pigs, at basel ine, after 12 mmHg PMOP and after an intravascular load with 10 ml/kg hydro xylethylstarch (HES). Results: PMOP increased SPV from 12.9+/-4.9 to 16.9+/-5.5 mmHg (P<0.05) and decreased pulmonary compliance, with no change in PAOP or end-diastolic ar ea assesssed by TTE. Intravascular volume loading significantly decreased S PV from 16.9+/-5.5 to 11.2+/-4.9 mmHg and Delta Down from 9.9+/-7.1 to 5.2/-4.5 (P<0.05), and increased PAOP and end-diastolic area. Significant corr elation between changes in Delta Down and EDA was noted following HES (r=0. 78, P<0.05). Conclusion: In anaesthetized pigs, the creation of a PMOP alters SPV, likel y by decreasing lung compliance. Once PMOP is established, changes in cardi ac preload could be estimated by SPV analysis.