Agreements between mean arterial pressure from radial and femoral artery measurements in refractory shock patients

Radial and femoral artery catheterization is the most common procedure for monitoring patients with shock. However, a disagreement in mean arterial pressure (MAP) between the two sites has been reported. Hence, the aim of this study was to compare the MAP from the radial artery (MAP radial ) with that of the femoral artery (MAP femoral ) in patients with refractory shock. A prospective study was conducted in the medical intensive care unit. The radial and femoral were simultaneously measured MAP in the patients every hour, for 24 hours. In total, 706 paired data points were obtained from 32 patients. MAP radial strongly correlated with MAP femoral (r = 0.89, p <0.0001). However, overall MAP radial was significantly lower than MAP femoral 7.6 mmHg. The bias between MAP radial and MAP femoral was -7.6 mmHg (95% limits of agreement (LOA), -24.1 to 8.9). In the subgroup of patients with MAP radial < 65 mmHg, MAP radial moderately correlated with MAP femoral (r = 0.63) and the bias was increased to -13.0 mmHg (95% LOA, -28.8 to 2.9). There were 414 (58.6%) measurements in which the MAP gradient between the two sites was > 5 mmHg. In conclusion, the radial artery significantly underestimated MAP compared with the femoral artery in patients with refractory shock.