Agreement between radial and femoral arterial blood pressure measurements during orthotopic liver transplantation.

OBJECTIVE To study agreement between radial and femoral arterial pressure measurements in orthotopic liver transplantation (OLTx) surgery to determine whether arterial cannulation sites are interchangeable. DESIGN, SETTING AND PARTICIPANTS Prospective observational study of 25 patients undergoing OLTx surgery. METHODS Radial and femoral arteries were cannulated with standardised arterial line kits. Radial and femoral mean arterial pressure (MAP), systolic arterial pressure (SAP), diastolic arterial pressure (DAP) and pulse pressure (PP) were measured at four time points (30 minutes after induction of anaesthesia, 30 minutes after the start of the anhepatic phase, 30 minutes after liver graft reperfusion and 30 minutes after the start of bile duct anastomosis). MAIN OUTCOME MEASURES The bias, precision and limits of agreement between radial and femoral arterial pressures were calculated in accordance with Bland-Altman statistics. RESULTS Radial-femoral differences in MAP (mean difference, 4.8 mmHg [SD, 4.5 mmHg]), limits of agreement (- 13.6 and 8.8, P < 0.001) and DAP showed clinically acceptable agreement between measurement sites across all time points. However, clinically significant differences between radial and femoral SAPs (mean difference, - 14.9 mmHg [SD, 24.8 mmHg]) and limits of agreement (- 63.5 and 33.7, P < 0.001) occurred overall. This difference started after portal vein clamping and remained significant throughout the remainder of the operation. CONCLUSION Radial artery SAP underestimates femoral artery measurements significantly but unpredictably. As femoral measurement is more likely to reflect central arterial pressure, radial SAP measurement is not reliable in adults undergoing OLTx.