Respiratory Rate as a Predictor of Clinical Deterioration and Mortality: A Scoping Review.

Introduction: Respiratory rate (RR) is a critical vital sign for assessing a patient's respiratory and overall health status. Despite its importance, RR is often underutilized and inconsistently measured in clinical practice. Monitoring RR can identify early signs of clinical deterioration, as it is often the first vital sign to deviate when a patient's condition worsens. This scoping review aims to map the current evidence on the role of RR monitoring in predicting mortality among hospitalized adult patients. We also evaluate the association of RR monitoring with early detection of clinical deterioration.

Method: A scoping review was performed using a structured search strategy across MEDLINE Ovid, EMBASE Ovid, and PubMed. The search was structured using the PICO framework, with mortality defined as the primary outcome of interest. Inclusion criteria were randomized controlled trials, cohort, cross-sectional, and observational studies in English, involving adults aged ≥ 16 years. Exclusion criteria included reviews, meta-analyses, and nonhuman studies. Two independent reviewers screened articles, with disagreements resolved by a third reviewer. Data extraction included study design, outcomes, and study-reported limitations.

Results: The literature search identified 881 records, with 562 studies screened after removing duplicates. After final screening, 21 studies were included, with sample sizes ranging from 34 to 556,848 patients. Most studies were observational, including 6 retrospective, 10 prospective, 1 case-control, and 2 comparative cohort studies. RR was reported to be frequently associated with mortality and clinical deterioration; though findings varied depending on clinical context and measurement method. Continuous monitoring detected more cases of sustained respiratory abnormalities than intermittent measurements and could hypothetically lead to earlier clinical interventions; though clinical impact requires further investigation.

Conclusion: RR was commonly identified as a predictor of mortality and clinical deterioration, with continuous monitoring showing higher detection rates of respiratory abnormalities compared with intermittent monitoring. However, variations in outcomes and study design highlight the need for standardized measurement.

Editorial comment: This scoping review presents current knowledge about how respiratory rate monitoring and assessment can inform about clinical deterioration with acute illness requiring hospitalization.