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 h. 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.