Vasopressor Use for Severe Hypotension-A Multicentre Prospective Observational Study

Abstract

Background: The optimal approach to titrate vasopressor therapy is unclear. Recent sepsis guidelines recommend a mean arterial pressure (MAP) target of 65 mmHg and higher for chronic hypertensive patients. As data emerge from clinical trials comparing blood pressure targets for vasopressor therapy, an accurate description of usual care is required to interpret study results. Our aim was to measure MAP values during vasopressor therapy in Canadian intensive care units (ICUs) and to compare these with stated practices and guidelines.

Method: In a multicenter prospective cohort study of critically ill adults with severe hypotension, we recorded MAP and vasopressor doses hourly. We investigated variability across patients and centres using multivariable regression models and Analysis of variance (ANOVA), respectively.

Results: We included data from 56 patients treated in 6 centers. The mean (standard deviation [SD]) age and Acute Physiology and Chronic Health Evaluation (APACHE) II score were 64 (14) and 25 (8). Half (28 of 56) of the patients were at least 65 years old, and half had chronic hypertension. The patient-averaged MAP while receiving vasopressors was 75 mm Hg (6) and the median (1st quartile, 3rd quartile) duration of vasopressor therapy was 43 hours (23, 84). MAP achieved was not associated with history of underlying hypertension (p = 0.46) but did vary by center (p<0.001).

Conclusions: In this multicenter, prospective observational study, the patient-level average MAP while receiving vasopressors for severe hypotension was 75 mmHg, approximately 10 mmHg above current recommendations and stated practices. Moreover, our results do not support the notion that clinicians tailor vasopressor therapy to individual patient characteristics such as underlying chronic hypertension but MAP achieved while receiving vasopressors varied by site.

Fig 1. MAP over time for hours on vasopressors.

Dots depict the individual patient hourly MAP measurements. The shaded area and thick line represent the LOESS smoothed hourly interquartile range and median respectively. The needles represent the number of patient contributing to each hour as labeled on the right axis.

Fig 2. Distribution of patient averaged MAP for hours on vasopressors by site.

Fig 3. Association between average hourly MAP and vasopressor dose.

a) All patients. b) Patients separated by chronic hypertension status. Vertical and horizontal dashed lines represent, respectively, the median-patient averaged arterial pressure and vasopressor dose.