Peripheral arterial blood pressure monitoring adequately tracks central arterial blood pressure in critically ill patients: an observational study.

INTRODUCTION: Invasive arterial blood pressure monitoring is a common practice in intensive care units (ICUs). Accuracy of invasive blood pressure monitoring is crucial in evaluating the cardiocirculatory system and adjusting drug therapy for hemodynamic support. However, the best site for catheter insertion is controversial. Lack of definitive information in critically ill patients makes it difficult to establish guidelines for daily practice in intensive care. We hypothesize that peripheral and central mean arterial blood pressures are interchangeable in critically ill patients.

METHODS: This is a prospective, observational study carried out in a surgical-medical ICU in a teaching hospital. Fifty-five critically ill patients with clinical indication of invasive arterial pressure monitoring were included in the study. No interventions were made. Simultaneous measurements were registered in central (femoral) and peripheral (radial) arteries. Bias and precision between both measurements were calculated with Bland-Altman analysis for the whole group. Bias and precision were compared between patients receiving high doses of vasoactive drugs (norepinephrine or epinephrine >0.1 microg/kg/minute or dopamine >10 microg/kg/minute) and those receiving low doses (norepinephrine or epinephrine <0.1 microg/kg/minute or dopamine <10 microg/kg/minute).

RESULTS: Central mean arterial pressure was 3 +/- 4 mmHg higher than peripheral mean arterial pressure for the whole population and there were no differences between groups (3 +/- 4 mmHg for both groups).

CONCLUSION: Measurement of mean arterial blood pressure in radial or femoral arteries is clinically interchangeable. It is not mandatory to cannulate the femoral artery, even in critically ill patients receiving high doses of vasoactive drugs.