Cardiopulmonary,echodopplercardiographic and cardiac output effects of isoflurane anaesthesia in male sheep

Abstract

Eight male Dorper sheep were anesthetized with isoflurane to evaluate the effects of anesthesia on cardiopulmonary parameters, echocardiographic variables and cardiac output (CO) using echocardiography methods compared with thermodilution. Heart rate (HR), respiratory rate (f R), systolic arterial pressure (SAP), diastolic arterial pressure (DAP) and mean arterial pressure (MAP) were recorded. CO was obtained by thermodilution using a pulmonary artery catheter (CO_THERMO), Teichholz method (CO_Teichholz) and pulmonary artery Doppler (CO_PA). Echocardiographic variables (interventricular septum (IVSs and IVSd), left ventricular chamber (LVIDs and LVIDd) and left ventricular free wall (LVFWs and LVFWd) in systole and diastole, respectively; ejection fraction (EF%); fractional shortening (FS%); pulmonary artery pressure gradient (PG), peak flow velocity (V_max) and velocity-time integral of the flow (VTI) were recorded. All parameters were measured at baseline and every 15 min during the transanesthetic and recovery periods (T15, T30, T45, T60, T15_REC, T30_REC, T45_REC, T60_REC). Significant reductions in SAP, MAP, DAP and CO_THERMO were observed during the transanesthetic period. Bland–Altman analysis comparing CO_THERMO and CO_Teichholz showed mean biases of 0.49 l min^–1 (limits of agreement (LOA), –2.12 to 3.12 l min^–1), 0.56 l min^–1 (–1.82 to 2.96 l min^–1) and 0.75 l min^–1 (–2.04 to 3.56 l min^–1) at baseline, during anesthesia and in recovery, respectively. For CO_THERMO and CO_PA, mean biases were −0.53 l min^–1 (–2.90 to 1.90 l min^–1), –0.66 l min^–1 (–4.72 to 3.39 l min^–1) and −0.94 l min^–1 (–4.62 to 2.73 l min^–1) at baseline, during anesthesia and in recovery, respectively. Isoflurane decreases blood pressure and CO without affecting echocardiographic parameters. CO values obtained by thermodilution and echocardiography methods are not interchangeable.