Summary of Methods/Findings:

Study #1: 

A prospective, observational study involving 24 adult patients in an ICU. The principal inclusion criterion for the study was the use of simultaneous monitoring with radial arterial and femoral arterial catheters in patients requiring vasoactive medications. 

The overall mean difference between radial and femoral MAP measurements was 4.27 mmHg, with limits of agreement ranging from −3.41 to 11.94 mmHg. In every case, femoral MAP was equal to or greater than radial MAP. There were also marked discrepancies in femoral and radial systolic arterial pressure, with a mean difference of 8.8 mmHg, with limits of agreement ranging from −21 to 38mmHg. 

However, multiple regression analysis failed to identify any statistically significant associations between a hemodynamic/demographic factor and MAP gradient. 

Study#2: 

A prospective study involving 60 adult patients who required high inotropic/vasopressor support on weaning from cardio-pulmonary bypass (CPB) in a cardiac surgery unit. Systolic arterial pressure, diastolic arterial pressure and mean arterial pressures were noted for both radial and femoral arteries at 5, 15 and 30 minutes of weaning from cardiopulmonary bypass. 

The MAPs after five minutes of weaning using femoral access were 76.28±10.21 mmHg versus 64.15±6.76 mmHg in radial arterial access (p-value <0.001). After 15 minutes of weaning from cardiopulmonary bypass, MAPs were 78.70±10.12 mmHg in femoral access versus 72.03±6.76 mmHg using peripheral access (p-value <0.001). SBP was also significantly higher in femoral artery as compared to the radial artery. 

Overall, the study noted a significant difference in systolic blood pressure, diastolic blood pressure and mean arterial pressure between the radial artery and femoral artery readings after 5, 15 and 30 minutes of weaning from cardiopulmonary bypass.

Summary: 

The first case demonstrated that femoral MAP was equal to or greater than radial MAP in all cases, but did not identify any statistically significant associations between a hemodynamic/demographic factor and MAP gradient. 

The second study noted a significant difference in systolic blood pressure, diastolic blood pressure and mean arterial pressure between the radial artery and femoral artery readings. 

References:

Galluccio, et al. Femoral–radial arterial pressure gradients in critically ill patients. Critical Care and Resuscitation, March 2009. Volume 11, Number 1. 

Ahmad RA, Ahmad S, Naveed A, Baig MAR. Peripheral arterial blood pressure versus Central arterial blood pressure monitoring in critically ill patients after Cardio-pulmonary Bypass. Pak J Med Sci. 2017;33(2):310-314.