Elsevier

Journal of Critical Care

Volume 49, February 2019, Pages 187-192
Journal of Critical Care

Cardiovascular
Rapid response team review of hemodynamically unstable ward patients: The accuracy of cardiac index assessment

https://doi.org/10.1016/j.jcrc.2018.09.002Get rights and content

Highlights

  • Non-invasive technology recorded the cardiac index in almost all rapid response team reviews

  • In such reviews for tachycardia and or hypotension, most patients had a high cardiac index

  • 1 in 5 intensive care doctors correctly identified the cardiac index category (low/normal/high)

  • Clinicians were unable to identify the presence of a low or a high cardiac index

Abstract

Purpose

Intensive care doctors commonly attend rapid response team (RRT) reviews of hospital-ward patients with hemodynamic instability and estimate the patient’s likely cardiac index (CI). We aimed to non-invasively measure the CI of such patients and assess the level of agreement between such measurements and clinically estimated CI categories (low <2L/min/m2, normal 2-2.99L/min/m2 or high ≥3L/min/m2).

Materials and methods

A prospective, observational study of non-invasive measurement and clinical estimation of CI categories in 50 adult hospital-ward patients who activated the RRT for ‘hemodynamic instability’ (tachycardia > 100BPM or hypotension < 90mmHg or both).

Results

The CI was measured in 47/50(94%) patients and the mean CI was 3.5(95% CI 3.2-3.7) L/min/m2. Overall, 30(64%) patients had a high CI, 13(28%) and 4(9%) had a normal and a low CI, respectively. The level of agreement between measured and clinically estimated CI categories was low(19.2%). Sensitivity and positive predictive values of clinical estimation were low(0% and 3.3% for high CI, and 0% and 50% for low CI, respectively).

Conclusions

Non-invasive CI measurement was possible in almost all hospital-ward patients triggering RRT review for hemodynamic instability. In such patients, the CI was high, and intensive care clinicians were unable to identify a low or a high CI state.

Introduction

Delay in assessment and management of deteriorating hospital-ward patients has been associated with increased morbidity and mortality [[1], [2], [3]]. In many countries, intensive care doctors have responded to these issues by implementing and staffing rapid response teams. Thus, rapid response teams (RRT) are now part of the work of many intensive care units worldwide and are an established approach to the recognition and treatment of such patients [4,5].

Approximately one third of RRT reviews are triggered by hypotension or tachycardia [[6], [7], [8]], hereafter termed ‘hemodynamic instability’ (HI). Currently, assessment of the hemodynamic state of such patients consists of clinical assessment based on examination and vital signs. Therefore, the diagnosis of either a low, a normal or a high cardiac index state is dependent on the skills and experience of the attending clinician.

Unfortunately, no studies to date have attempted to rapidly and objectively measure a patient's cardiac index during a RRT review for HI. This knowledge gap is due to the fact that currently available methods to measure cardiac output and index may be invasive, operator or reporter-dependent and intermittent (echocardiography), and require time and expertise to perform, monitor and evaluate. The ClearSight™ (Edwards, Irvine, CA, USA) is one of several novel non-invasive devices that can measure the CI and other hemodynamic parameters and is FDA approved for such use [[9], [10], [11], [12]].

Accordingly, the primary outcome was to non-invasively measure the CI of adult patients who trigger a RRT review for HI. The secondary outcomes were assessment of the level of agreement (LOA) between the CI obtained with such technology, and the CI estimated through clinical assessment by members of an intensive care-based RRT. Our hypothesis was that most patients would be in the low or normal CI category and that there would be a moderate level of agreement between clinical assessment and non-invasive measurement.

Section snippets

Selection and description of participants

This was a single-center, prospective, observational study conducted in a large metropolitan hospital where the RRT is intensive care led. Ethical approval (LNR/15/Austin/382) was obtained through the Institutional Review Board, which waived the need for informed consent. Adult patients age 18 or over who triggered a RRT review for tachycardia (>100 beats per minute(BPM)) or hypotension (< 90 mmHg) were included. Patients with Raynaud's disease or severe peripheral vascular disease were

Details of patient cohort

We non-invasively recorded the CI in almost all RRT reviews for HI (47 of 50, 94%). Three patients were excluded due to failure to obtain a reliable photoplethysmograph. In these 47 patients, we recorded over 4000 observations (median 115, IQR 73–137 observations per patient). Most were male (28, 60%), aged between 50 and 80 years (median 65, IQR: 57–77 years). Most patients had a least one comorbidity (39, 83%) and the median hospital length of stay was 6 days (IQR 3–11.5) (Table 1). Of the

Discussion

We non-invasively recorded the CI in hospital-ward patients triggering RRT review for HI. Two thirds of such patients had a high CI and a low CI was uncommon. Almost all patients with tachycardia or suspected vasodilatation had a high CI. However, there was poor agreement between the non-invasively measured and clinically estimated CI categories. Moreover, no clinicians correctly identified the CI category if the suspected cause for RRT activation was vasodilatation. Finally, clinicians were

Conclusions

We applied a novel non-operator dependent device to non-invasively measure CI in hospital-ward patients triggering review by an intensive care-based RRT for HI. We found that a high mean CI and a high CI category were common, while a low CI category was uncommon. Moreover, we found that ICU-based clinicians were unable to accurately estimate the CI category. Finally, such ICU-based clinicians were unable to identify the presence of a low CI or a high CI. These findings imply that, in selected

Sources of Funding

This study was supported by a $10,000 (AUD) unrestricted educational grant from Edwards Lifesciences, who also supplied some of the single-use finger probes. Edwards Lifesciences were not involved in any other capacity (study concept and design; data collection, analysis, and interpretation; writing and editing of the manuscript; decision to submit for publication). This work was supported by an unrestricted educational grant from the Austin Hospital Anesthesia and Intensive Care Trust Fund.

Acknowledgements

Preliminary data was presented in at the 2017 Australian and New Zealand Intensive Care Society Rapid Response Team Safety and Quality Annual Meeting in Sydney, 7th august 2017 and in poster form at the 2017 Australian and New Zealand Intensive Care Society Annual Scientific Meeting in the Gold Coast, 12th October 2017.

All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with

Non-regular abbreviations

    BMI

    Body Mass Index

    BSA

    Body Surface Area

    CE

    Clinical Estimation

    CI

    Cardiac Index

    CO

    Cardiac Output

    HI

    Hemodynamic Instability

    LOA

    Level of Agreement

    RRT

    Rapid Response Team

    NPV

    Negative Predictive Value

    NIM

    Non-Invasive Measurement

    PPV

    Positive Predictive Value

    PAC

    Pulmonary Artery Catheter

    SVI

    Stroke Volume Index

    SIRS

    Systemic Inflammatory Response Syndrome

    SVR

    Systemic Vascular resistance

    SVRI

    Systemic Vascular Resistance Index

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