Predictors of clinically relevant differences between noninvasive versus arterial blood pressure

Blood pressure (BP) measurements are important for managing patients with hypertensive emergencies (HE). Previous studies showed that there was significant difference between IABP and NIBP but no information whether these differences changed management. Our study investigated the factors associated with the differences affecting BP management of patients with HE.

This was a retrospective study involving adult patients admitted to a resuscitation unit. We screened all patients who received IABP upon admission between 06/01/2017 and 12/31/2017 as sample size calculation recommended 64 patients. Primary outcome was the clinical relevance of the difference of IABP vs. NIBP, which was defined as having both: a) difference of 10 mm of mercury (mmHg), and b) resulting in possible change of blood pressure managements according to treatment guidelines. We performed backward stepwise multivariable logistic regression to measure associations.

We analyzed 147 patients whose mean age was 69 (±16) years and included 69 (47%) patients with spontaneous intracerebral hemorrhage (sICH). Mean difference between IABP and NIBP was 21 (±16) mmHg while 41 (28%) patients who had difference affecting managements. In multivariable regression, sICH (Odd Ratios 13.5, 95%CI 2.3-79.5, p-value < 0.001) was significantly associated with clinically relevant difference between the two modalities of BP monitoring.

There was a large difference between IABP and NIBP among patients with hypertensive emergencies. Up to 30% of patients had clinically relevant differences. Patients with sICH were more likely to have differences affecting BP management. Further studies are needed to confirm our observation.