Comparison of Radial and Femoral Artery Site Invasive Blood Pressure Measurement in Septic Patients on High Dose of Noradrenaline: A Prospective Observational Study

Invasive arterial blood pressure monitoring is common in critically ill patients admitted in intensive care units (ICUs). The most common indication for invasive arterial blood pressure monitoring is for continuous measurement in hemodynamically unstable patients on vasopressor therapies Invasive arterial blood pressure monitoring is a standard of care during shock management in the ICU. The Surviving Sepsis Campaign international consensus guidelines (2016) recommend maintaining a mean arterial pressure (MAP) of 65 mmHg or greater, as a goal of initial resuscitation, and to apply vasopressors, if required, to maintain MAP at this level. The radial artery is most commonly used, with the femoral artery being the second choice; both site accounting as 92% of all arterial cannulations.

Accuracy of invasive blood pressure monitoring is crucial in evaluating the cardiocirculatory system and adjusting vasopressor therapy for hemodynamic support. However, the best site for catheter insertion is controversial. Compared with arterial pressure waveforms measured in the central arteries (eg, aorta or femoral artery), those at the periphery (eg, radial artery) characteristically have steeper upstrokes, higher systolic peaks, a later appearing diastolic notch, more prominent diastolic waves and lower end-diastolic pressure. Yet, under normal physiological conditions, only a negligible decrement in MAP occurs. In critically ill patients during aberrant hemodynamic conditions like septic shock, gradients in MAP may develop from the central to the peripheral arterial site.

There are some available studies where simultaneous measurement of radial and femoral was done in different patient population. In all studies where patients of cardiopulmonary bypass were included showed that there was significant difference in MAP and SBP between femoral and radial invasive blood pressure measurements with femoral site IBP being greater than radial site. Similar difference in SBP and MAP was noted in reperfusion stage of liver transplant patients. The difference was also found in septic shock patients in MAP with vasopressor usage but one study did not find significant difference in invasive MAP and SBP.

Work plan methodology:

This is a prospective observational study to know the difference in blood pressure recordings of invasive arterial BP (radial versus femoral site) in patients of septic shock on high dose of noradrenaline therapy (≥0.1 mcg/kg/min) for at least 30 minutes. Participant will be included from ICU of department of critical care medicine. All adult critically ill patients with septic shock requiring noradrenaline infusion (≥0.1 mcg/kg/min) will be considered for inclusion in this study. Participant will be included if treating team considered to change the site of arterial invasive blood pressure monitoring from radial to femoral site (same side, left or right).