Acute Heart Failure in the Emergency Department: Respiratory Rate as a Risk Predictor

Area of Science:

• Cardiology
• Emergency Medicine
• Respiratory Physiology

Background:

• Acute heart failure (AHF) patient stratification in the Emergency Department (ED) relies on risk scores.
• Vital signs like blood pressure (BP), heart rate (HR), and respiratory rate (RR) are routinely monitored.
• Measurement of RR is often overlooked despite its potential clinical significance.

Purpose of the Study:

• To investigate the predictive value of respiratory rate (RR) and its derivative indices in classifying patients with acute heart failure (AHF).
• To assess the utility of RR-derived metrics for predicting patient outcomes in the ED setting.

Main Methods:

• Analysis of vital signs, including HR and RR, recorded upon admission in the ED.
• Calculation and evaluation of derivative indices such as HR:RR ratio and Respiratory Efficacy Index (REFI = RR×100/SatO2).
• Utilizing Receiver Operating Characteristic (ROC) curves to determine the accuracy, sensitivity, and specificity of these indices in predicting outcomes.

Main Results:

• Individual HR and RR measurements did not effectively discriminate patient outcomes regarding hospitalization length, ICU admission, mechanical ventilation, or mortality.
• Derivative indices, specifically the HR:RR ratio and REFI, demonstrated the ability to differentiate patients based on hospitalization length.
• ROC analysis revealed high accuracy, sensitivity, and specificity for REFI >27 and HR:RR ≥4 in predicting mortality and ICU admission.

Conclusions:

• Respiratory rate (RR) and its derivative indices (HR:RR, REFI) are valuable, easily accessible vital signs in the ED.
• These metrics show significant potential for improving risk stratification and outcome prediction in acute heart failure (AHF) patients.
• Revitalization of RR monitoring and analysis in the ED is warranted for enhanced patient management.