Agreement between invasive blood pressure measured centrally and peripherally in anaesthetized horses

Abstract

ObjectiveTo determine the agreement of invasive blood pressure measured in the facial, metatarsal and carotid arteries, and evaluate the effects of two haemodynamic conditions on agreement. Study designProspective randomized study. AnimalsA group of eight horses aged 7 (4–23) years with a body weight of 493 ± 33 kg. MethodsHorses were anaesthetized and positioned in dorsal recumbency. Invasive blood pressure was measured simultaneously via catheters placed in the facial, metatarsal and carotid arteries. Cardiovascular function and agreement between arteries was assessed before and during administration of phenylephrine and sodium nitroprusside. These were administered until carotid mean pressure (MAPc) increased or decreased from baseline (65 ± 5) to >90 or <50 mmHg, respectively. Data recorded at each sample time included systolic (SAP), mean (MAP) and diastolic (DAP) arterial pressures for carotid (c), facial (f) and metatarsal (m) arteries as well as cardiac output (Q˙t) and systemic vascular resistance (SVR). Bland–Altman analysis was used to assess agreement between peripheral and central sites, and regression analysis to determine influence of Q˙t and SVR. ResultsThe largest difference was observed in SAPc and SAPm with a bias and limits of agreement (LOA) of 2 (−15 to 19) mmHg. The bias (LOA) for MAPc and MAPf was 2 (−4 to 9) mmHg and for MAPc and MAPm was 5 (−4 to 14) mmHg. The best agreement for DAP was seen between DAPc and DAPf with bias (LOA) of 1 (−3 to 5) mmHg. Regression analysis indicated marginal influence on agreement by Q˙t on MAPc and MAPf. Conclusions and clinical relevanceMAP and DAP of the carotid artery were higher than those of the peripheral arteries, which may lead to overzealous treatment of hypotension, albeit maintaining central pressures. Q˙t and SVR did not largely influence the difference between sites.