Elsevier

Resuscitation

Volume 62, Issue 2, August 2004, Pages 137-141
Resuscitation

Association between clinically abnormal observations and subsequent in-hospital mortality: a prospective study

https://doi.org/10.1016/j.resuscitation.2004.03.005Get rights and content

Abstract

Background: Patients with unexpected in-hospital cardiac arrest often have an abnormal clinical observation prior to the arrest. Previous studies have suggested that a medical emergency team responding to such patients may decrease in-hospital mortality from cardiac arrest, but the association between any abnormal clinical observation and subsequent increased mortality has not been studied prospectively. The aim of this study was to determine the predictive value of selected abnormal clinical observations in a ward population for subsequent in-hospital mortality. Design and setting: Prospective data collection in five general hospital ward areas at Dandenong Hospital, Victoria, Australia. Interventions: None. Results: During the study period, 6303 patients were admitted to the study areas. Of those, 564 (8.9%) experienced 1598 pre-determined clinically abnormal events and 146 of these patients (26%) died. The two commonest abnormal clinical events were arterial oxygen desaturation (51% of all events), and hypotension (17.3% of all events). Using a multiple linear logistic regression model, there were six clinical observations which were significant predictors of mortality. These were: a decrease in Glasgow Coma Score by two points, onset of coma, hypotension (<90 mmHg), respiratory rate <6 min−1, oxygen saturation <90%, and bradycardia >30 min−1. The presence of any one of the six events was associated with a 6.8-fold (95% CI: 2.7–17.1) increase in the risk of mortality. Conclusions: Six abnormal clinical observations are associated with a high risk of mortality for in-hospital patients. These observations should be included as criteria for the early identification of patients at higher risk of unexpected in-hospital cardiac arrest.

Sumàrio

Contexto: Os doentes vı́timas de paragem cardı́aca intra-hospitalar inesperada têm frequentemente uma observação clı́nica anormal antes da paragem. Estudos prévios sugerem que se esses doentes forem socorridos por uma equipa médica de emergência pode-se diminuir a mortalidade intra-hospitalar por paragem cardı́aca, mas a associação entre alterações clı́nicas e aumento da mortalidade subsequente não foi estudada de forma prospectiva. O objectivo deste estudo foi determinar o valor preditivo, para mortalidade intra-hospitalar de alterações clı́nicas, seleccionadas, numa população de enfermaria. Desenho: Recolha prospectiva de dados em cinco áreas de enfermaria geral hospitalar no Hospital Dandenong, Victoria, Austrália. Intervenções: Nenhuma. Resultados: Durante o perı́odo de estudo, foram admitidos 6303 doentes nas áreas de estudo. Em 564 (8.9%) ocorreram 1598 alterações clı́nicas de um grupo pré-determinado e 146 (26%) morreram. As duas alterações clı́nicas mais frequentes foram a dessaturação de oxigénio arterial (51% de todos os eventos), e a hipotensão (17.3% de todos os eventos). Utilizando um modelo de regressão logı́stica linear múltipla, houve seis observações clı́nicas que significativamente preditivas de mortalidade: Deterioração do Score da Escala de Coma de Glasgow em 2 pontos, inı́cio de coma, hipotensão (<90 mmHg), frequência respiratória <6 min, saturação de oxigénio <90%, e bradicardia >30 min. A presença de qualquer um destes seis acontecimentos associou-se ao aumento de 6.8 vezes (95% CI: 2.7–17.1) no risco de morte. Conclusões: Identificaram-se seis alterações clı́nicas associadas a aumento de risco de morte em doentes hospitalizados. Estas observações devem ser incluı́das como critérios para a identificação precoce dos doentes com risco mais elevado de paragem cardı́aca intra-hospitalar inesperada.

Resumen

Antecedentes: Los pacientes con paro cardı́aco no esperado intrahospitalario tienen frecuentemente hallazgos clı́nicos anormales previos al paro. Estudios previos sugieren que el equipo de emergencias médicas que responde a tales pacientes podrı́a disminuir la mortalidad intrahospitalaria, pero la asociación entre los hallazgos clı́nicos anormales y mortalidad aumentada subsiguiente no ha sido estudiada prospectivamente. El objetivo de este estudio fue determinar el valor de determinados hallazgos clı́nicos anormales para predecir mortalidad intrahospitalaria. Diseño y Ambiente: Recolección prospectiva de datos en cinco áreas de salas generales en el Hospital Dandenong, en Victoria, Australia. Intervenciones: ninguna. Resultados: Durante el perı́odo de estudio, 6303 pacientes fueron admitidos en las áreas del estudio. De aquellos, 564 (8.9%) experimentaron 1598 eventos clı́nicamente anormales y 164 de estos pacientes (26%) murieron. Los dos eventos clı́nicos anormales mas comunes fueron la des saturación (51% de las alertas), y la hipotensión (17.3% de los eventos). Se analizó usando un modelo de regresión logı́stica linear múltiple, y se encontraron seis hallazgos clı́nicos que eran predictores significativos de mortalidad. Estos fueron: una disminución en dos puntos en la escala de coma de Glasgow, instalación de coma, hipotensión (<90 mmHg), frecuencia respiratoria < 6 min−1, saturación de oxı́geno <90%, y bradicardia >30 min−1. La presencia de cualquiera de estos 6 eventos se asoció con un aumento en 6.8 veces del riesgo de mortalidad (95% CI, 2.7–17.1). Conclusiones: Seis hallazgos clı́nicos anormales están asociadas con mayor riesgo de mortalidad intrahospitalaria de pacientes. Estos hallazgos clı́nicos deberı́an incluirse como criterios para la identificación temprana de pacientes en mayor riesgo de paro cardı́aco intrahospitalario inesperado.

Introduction

Unexpected in-hospital cardiac arrest is common and associated with a high mortality rate [1], [2], [3], [4]. When cardiac arrest occurs in a general ward area, many hospitals use a “cardiac arrest team” to respond and provide immediate resuscitation. However, this approach has not been associated with an improvement in the mortality rate.

Previous studies have suggested that 66–84% of in-hospital cardiac arrests are preceded by at least one abnormal clinical observation [5], [6], [7], [8]. Traditionally, these observations are reported by nursing staff to junior medical staff, leading to delays in evaluation and definitive care.

In order to decrease the incidence of unexpected cardiac arrest, the concept of the medical emergency team (MET) has been described [9], [10], [11]. The MET consists of experienced clinicians who are called to respond immediately to patients with any abnormal clinical observations and/or laboratory findings. The rationale of a MET system is that early intervention might prevent subsequent cardiac arrest and/or unplanned intensive care admission. We reported in a previous study that the introduction of a MET significantly decreased the mortality rate of unexpected cardiac arrest in our hospital [11].

However, the clinical criteria for the paging of the MET have been based on retrospective studies of the clinically abnormal observations which have been found to precede cardiac arrest. This methodology may significantly underestimate the true incidence of these observations among hospital in-patients. Therefore, we undertook this study to determine prospectively the incidence of selected abnormal clinical observations and their association with discharge mortality status for in-hospital patients.

Section snippets

Study design and methods

This study was a prospective, observational investigation at Dandenong Hospital, Melbourne, Victoria, Australia. Dandenong Hospital is a 320-bed, university affiliated teaching hospital and provides most clinical services (except elective cardiac surgery and neurosurgery) to a population of approximately 500,000 in the outer south-eastern suburbs of Melbourne, Australia. During 1999, the hospital admitted 28,000 patients and there were 520 ICU admissions.

The study was conducted as part of an

Results

During the 7-month study period, 6303 patients were admitted to the study wards, with a total of 38,115 bed-days and a mean length of stay of 6 days. During this period, 1598 abnormal bedside observations were observed in 564 patients; making the incidence of abnormal bed observations 4.2 per 100 bed-days in 8.9% patients.

The prevalence of adverse events is shown in Fig. 1. The two commonest events were the bedside observation of oxygen desaturation to less than 90% (on or off oxygen therapy),

Discussion

Recent studies have proposed that the introduction of a MET may prevent subsequent unexpected cardiac arrest and therefore decrease in-hospital mortality [10], [11]. However, the clinical criteria which have been used in previous reports for the calling of a MET have been based on clinical experience and/or retrospective data [5], [6], [7], [8], [9], [13]. Since the introduction of a MET requires additional resources, the development of accurate clinical criteria is required to avoid

References (13)

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