The prevalence and significance of abnormal vital signs prior to in-hospital cardiac arrest

Abstract

Background: Patients suffering in-hospital cardiac arrest often show signs of physiological deterioration before the event. The purpose of this study was to determine the prevalence of abnormal vital signs 1-4h before cardiac arrest, and to evaluate the association between these vital sign abnormalities and in-hospital mortality.

Methods: We included adults from the Get With the Guidelines(®)- Resuscitation registry with an in-hospital cardiac arrest. We used two a priori definitions for vital signs: abnormal (heart rate (HR) ≤ 60 or ≥ 100 min(-1), respiratory rate (RR) ≤ 10 or >20 min(-1) and systolic blood pressure (SBP) ≤ 90 mm Hg) and severely abnormal (HR ≤ 50 or ≥ 130 min(-1), RR ≤ 8 or ≥ 30 min(-1) and SBP ≤ 80 mm Hg). We evaluated the association between the number of abnormal vital signs and in-hospital mortality using a multivariable logistic regression model.

Results: 7851 patients were included. Individual vital signs were associated with in-hospital mortality. The majority of patients (59.4%) had at least one abnormal vital sign 1-4h before the arrest and 13.4% had at least one severely abnormal sign. We found a step-wise increase in mortality with increasing number of abnormal vital signs within the abnormal (odds ratio (OR) 1.53 (CI: 1.42-1.64) and severely abnormal groups (OR 1.62 (CI: 1.38-1.90)). This remained in multivariable analysis (abnormal: OR 1.38 (CI: 1.28-1.48), and severely abnormal: OR 1.40 (CI: 1.18-1.65)).

Conclusion: Abnormal vital signs are prevalent 1-4h before in-hospital cardiac arrest on hospital wards. In-hospital mortality increases with increasing number of pre-arrest abnormal vital signs as well as increased severity of vital sign derangements.

Keywords: Blood pressure; Cardiopulmonary resuscitation; Heart arrest; Heart rate; Mortality; Respiration.

Figure 1. Patient Inclusion/Exclusion Criteria

A total of 7,851 patient were included in the primary study cohort

Figure 2. The Association Between Individual Vital Signs and Mortality – Univariate Analysis

The * indicates statistical significance compared to the reference group (marked with a #) defined as the group with the lowest mortality (50–59 min⁻¹ for heart rate [A], 11–15 min⁻¹ for respiratory rate [B] and 170–179 mm Hg for systolic blood pressure [C]).

Figure 3. The Association Between Number of Abnormal Vital Signs and Mortality

We found a step-wise increase in mortality with increasing number of abnormal vital signs using both of our predefined categories (abnormal: OR 1.53 (CI: 1.42 – 1.64) per increased abnormal vital sign, and severely abnormal: OR 1.62 [CI: 1.38 – 1.90] per increased abnormal vital sign). Error bars represent exact binomial 95% confidence intervals.