Comparison between invasive and noninvasive blood pressure measurements in critically ill patients receiving inotropes.

OBJECTIVE: The aim of this study was to compare invasive and noninvasive monitoring of blood pressure (BP) in patients on inotropes.

SETTINGS AND DESIGN: This study was carried out in the ICU of a tertiary care centre. The design was comparative analytical.

PATIENTS AND METHODS: Thirty-six adult patients receiving inotropes with invasive arterial BP monitoring were studied. Systolic and diastolic BPs were recorded simultaneously using invasive (radial arterial cannula) and noninvasive (Philips Intellivue MP-60 oscillometric monitor attached to the opposite arm) methods every 30 min.

STATISTICAL ANALYSIS: Agreement (precision) between both the methods was assessed using Bland-Altman analysis. A difference of more than 10 mmHg was considered clinically unacceptable. Linear regression of difference with invasive BP and analysis of variance with Tukey's correction of difference with the number of inotropes were carried out.

RESULTS: Overall, 1400 pairs of systolic and diastolic BP measurements were obtained. Systolic and diastolic pressures showed a difference of 2.3±16.9 and 0.7±10.6 mmHg, respectively. In all, 93.4% of systolic and 98.6% of diastolic pressure measurements were within the limits of agreement. The difference was clinically acceptable in 54.2% of measurements of systolic and 74.1% of diastolic measurements. Both systolic and diastolic BP differences were correlated with the number of inotropes that the patient was receiving.

CONCLUSION: Noninvasive BP measurement using an oscilllometric monitor (Philips Intellivue MP-60) is not a reliable alternative to invasive intra-arterial measurement in patients receiving inotropes. The observed difference increased with the number of inotropes that the patient was receiving.