Overnight Vital Signs — Are They Always Beneficial?

Financial Disclosure: Hospital Medicine Alert's physician editor, Kenneth P. Steinberg, MD, peer reviewer William Thompson, MD, executive editor Russ Underwood, and associate managing editor Jill Drachenberg have no relevant financial relationship related to the material presented in this issue.

By Jennifer A. Best, MD, FACP, Assistant Professor, University of Washington School of Medicine, Seattle, WA. Dr. Best reports no financial relationships in this field of study.

SYNOPSIS: Low MEWS score may be beneficial in identifying a subset of hospitalized patients unlikely to benefit from nocturnal vital sign monitoring.

SOURCE: Yoder JC, Yuen TC, Churpek MM, Arora VM, Edelson DP. A prospective study of nighttime vital sign monitoring frequency and risk of clinical deterioration. JAMA Intern Med. Published online July 1, 2013

The practice of checking vital signs at regular intervals in hospitalized patients throughout the day and night (i.e. q4 hours) is long standing, yet has never been prospective evaluated in regards to its utility. Though new derangements in temperature, blood pressure, respiratory rate or pulse may herald the development of a new or worsening condition, routine interruptions in a patient's clinical care or sleep routine may increase fatigue and decrease patient satisfaction. This practice is also labor intensive, which may decrease staff satisfaction and detract from other clinical duties.

Increasingly, scoring systems such as the Modified Early Warning System (MEWS) Score have been used to identify a subset of hospitalized patient at higher risk of clinical deterioration. The MEWS score is a composite of five variables: temperature (in degrees C), systolic blood pressure, pulse, respiratory rate and level of consciousness, as determined by the acronym AVPU (whether the patient is Alert, uses his Voice, responds to Pain or is Unresponsive). Each of these variables is assigned a point score of 0-3, based on its percent derangement from baseline or absolute value. A MEWS score of 5 or more has been shown to be linked with higher mortality and risk of ICU admission.1 Until now, it has been unknown whether the MEWS score may also identify a subset of patients unlikely to benefit from frequent monitoring of vital signs, notably overnight, where the potential for sleep interruption is greatest.

In a research letter published online in the July 1, 2013 issue of JAMA Internal Medicine, Dr. Jordan Yoder and hospital medicine colleagues at the University of Chicago describe a prospective, cohort study in which the risks of adverse events and sleep disruption for hospitalized patients were stratified by an evening MEWS score, documented prior to 11:00 pm. Vital sign data were extracted from the electronic health record. Tracked adverse events included ICU transfers and cardiac arrests within 24 hours of MEWS score documentation. Disruptions and adverse event rates were then compared across all MEWS categories.

By study's end, 54,096 patients (reflecting 182,828 patient-days) had been included. The study population was predominately female (57%) with a median age of 56 years and a median MEWS score of 2. A total of 1699 adverse events occurred. As MEWS score increased, the adverse event rate also increased (ranging from 5 events per 1000 patient-days for scores of ≤1 to 157 events per 1000 patient-days for scores of ≥7; P=0.003). All patients, regardless of MEWS score, were found to have had frequent vital signs checks, with a median of 2 vital sign checks nightly, accounting for at least 1 sleep disruption for the vast majority of nights (99%). In addition, 45% of these sleep disruptions affected patients with MEWS scores of ≤1 — the population shown to have the lowest adverse event rates.

These investigators conclude that in this study population, routine vital sign collection was common and did not appear to be linked to clinical risk, as patients with the lowest MEWS scores had vitals checked as frequently as those with higher scores. A low evening MEWS score was found to be associated with a low risk of cardiac arrest and ICU admission, suggesting that some evening disruptions might be eliminated without harm to these patients. Such elimination may reduce sleep deprivation, which has been linked to readmissions.2 Furthermore this may allow for shifts in resource allocation toward more acutely ill hospitalized patients, allowing for earlier recognition of decline and rapid intervention.

Though this is a single site study utilizing only one clinical index of risk and does not investigate the risks and benefits of specific intervals of vital sign monitoring (i.e. q4H, q6H, q8H), these results suggest that routine monitoring of overnight vital signs for all patients may not be beneficial. These data suggest that further determination of the effects of more targeted vital sign monitoring on a general hospital population from the standpoint of safety, sleep deprivation and patient satisfaction may be worthwhile.


  1. Subbe CP, Kruger M, Rutherford P, Gemmel L. Validation of a modified early warning score in medical admissions. QJM 2001;94(10):521-526.
  2. Dharmarajan K, Hseih AF, Lin Z, et al. Diagnoses and timing of 30-day readmissions after hospitalization for heart failure, acute myocardial infarction or pneumonia. JAMA 2013;309(4):355-363.