Comparison of invasive and non-invasive blood pressure measurements in anesthetized female Dorset cross-bred lambs (Ovis aries)

The purpose of this study was to determine the level of agreement between invasive and noninvasive blood pressure measurements in anesthetized, non-surgically manipulated Dorset cross-bred lambs. Twelve healthy female Dorset cross-bred lambs, weighing 37.3 ± 7.4 kg (mean ± SD) underwent isoflurane anesthesia for simultaneous measurement of systolic arterial pressure (SAP), mean arterial pressure (MAP) and diastolic arterial pressure (DAP) from an invasive blood pressure source and a noninvasive oscillometric source (O-NIBP). The femoral artery was catheterized for invasive blood pressure measurements, while noninvasive blood pressure was measured from a cuff placed on the antebrachium. The Bland-Altman method was used to calculate agreement between SAP, MAP and DAP measurements. The bias ± SD between SAP, MAP and DAP measurements was 3.6 ± 12.0, 4.9 ± 9.1 mmHg and 4.1 ± 8.0, respectively. The 95% limits of agreement for SAP, MAP and DAP were − 19.9 to 27.1, −13.0 to 22.8 mmHg, and − 11.7 to 19.9, respectively. Overall, agreement was poor between femoral IBP and O-NIBP monitoring techniques in anesthetized Dorset cross-bred lambs, with O-NIBP underestimating the femoral IBP. Arterial blood pressure should be most accurately measured using an invasive blood pressure monitoring technique in lambs undergoing isoflurane anesthesia.