A Comparison of the Shock Index and Conventional Vital Signs to Identify Acute, Critical Illness in the Emergency Department☆,☆☆,★
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INTRODUCTION
Conventional vital signs (eg, heart rate [HR], systolic blood pressure [SBP], and diastolic blood pressure [DBP]), are commonly measured to evaluate hemodynamic stability of critically ill patients in the emergency department. However, several studies have established that the normal values of such measurements may conceal significant deficiency in systemic oxygenation and cardiac function and an increased likelihood of death.1, 2, 3 The shock index (SI) is a ratio calculated to weigh HR and
MATERIALS AND METHODS
This quasi-prospective study was approved by the Institutional Review Board for Human Research of Henry Ford Hospital. The purpose was to identify if either conventional vital signs (HR, SBP, and DBP) or SI measured on arrival to the ED could identify acute, critical illness requiring immediate treatment and admission to the ICU. A consecutive sample of 275 patients who presented to the ED for urgent medical care served as the study population. Exclusion criteria were age less than 18 years,
RESULTS
Our study included a total of 275 patients, of whom 145 were men. Mean age was 52±20 years. The mean SI was 0. 7±0.3 and ranged from 0.3 to 3.0 (normal range, 0.5 to 0.7).4 Patients were divided into two groups (1 and 2) using an SI of 0.9 as a cutoff value because an SI of more than 0.9 was found to be clinically significant and frequently associated with deficient global oxygenation and ischemia after resuscitation and hemodynamic stabilization.6, 7
The nature of acute illness in these
DISCUSSION
Conventional vital signs (HR, SBP, and DBP) are measured commonly to evaluate cardiovascular and hemodynamic stability in the ED, although apparent normality of these measurements can mask significant global ischemia and cardiac dysfunction in critically ill patients.8, 9, 10 Allgower et al were the first to use the SI to evaluate patients presenting with gastrointestinal hemorrhage.11 They found that an elevation of the SI was an earlier and better indicator than HR, SBP, or DBP measured
CONCLUSION
The stability of conventional vital signs (HR, SBP, and DBP) considered individually failed to identify critically ill patients in the ED. An elevation of the SI to more than 0.9 and stable vital signs implied a critical illness that required immediate treatment, admission to the hospital, and continued intensive monitoring and therapy in the ICU. The SI is a ratio calculated to weigh HR and SBP differently and may be better than HR, SBP, and DBP measured individually to identify critically ill
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Cited by (0)
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From the Department of Emergency Medicine, Henry Ford Hospital, Detroit, Michigan.
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Address for reprints: Mohamed Rady, MD, PhD, Department of Emergency Medicine, Henry Ford Hospital, 2799 West Grand Blvd, Detroit, Michigan 48202
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Reprint no. 47/1/59539