| Assessment of the impedance cardiogram recorded by an automated external defibrillator during clinical cardiac arrest. | |
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MedLine Citation:
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PMID: 19864942 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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OBJECTIVE: To assess the impedance cardiogram recorded by an automated external defibrillator during cardiac arrest to facilitate emergency care by lay persons. Lay persons are poor at emergency pulse checks (sensitivity 84%, specificity 36%); guidelines recommend they should not be performed. The impedance cardiogram (dZ/dt) is used to indicate stroke volume. Can an impedance cardiogram algorithm in a defibrillator determine rapidly circulatory arrest and facilitate prompt initiation of external cardiac massage? DESIGN: Clinical study. SETTING: University hospital. PATIENTS: Phase 1 patients attended for myocardial perfusion imaging. Phase 2 patients were recruited during cardiac arrest. This group included nonarrest controls. INTERVENTIONS: The impedance cardiogram was recorded through defibrillator/electrocardiographic pads oriented in the standard cardiac arrest position. MEASUREMENTS AND MAIN RESULTS: Phase 1: Stroke volumes from gated myocardial perfusion imaging scans were correlated with parameters from the impedance cardiogram system (dZ/dt(max) and the peak amplitude of the Fast Fourier Transform of dZ/dt between 1.5 Hz and 4.5 Hz). Multivariate analysis was performed to fit stroke volumes from gated myocardial perfusion imaging scans with linear and quadratic terms for dZ/dt(max) and the Fast Fourier Transform to identify significant parameters for incorporation into a cardiac arrest diagnostic algorithm. The square of the peak amplitude of the Fast Fourier Transform of dZ/dt was the best predictor of reduction in stroke volumes from gated myocardial perfusion imaging scans (range = 33-85 mL; p = .016). Having established that the two pad impedance cardiogram system could detect differences in stroke volumes from gated myocardial perfusion imaging scans, we assessed its performance in diagnosing cardiac arrest. Phase 2: The impedance cardiogram was recorded in 132 "cardiac arrest" patients (53 training, 79 validation) and 97 controls (47 training, 50 validation): the diagnostic algorithm indicated cardiac arrest with sensitivities and specificities (+/- exact 95% confidence intervals) of 89.1% (85.4-92.1) and 99.6% (99.4-99.7; training) and 81.1% (77.6-84.3) and 97% (96.7-97.4; validation). CONCLUSIONS: The impedance cardiogram algorithm is a significant marker of circulatory collapse. Automated defibrillators with an integrated impedance cardiogram could improve emergency care by lay persons, enabling rapid and appropriate initiation of external cardiac massage. |
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Authors:
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Nick Alexander Cromie; John Desmond Allen; C?sar Navarro; Colin Turner; John McC Anderson; A A Jennifer Adgey |
Publication Detail:
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Type: Journal Article |
Journal Detail:
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Title: Critical care medicine Volume: 38 ISSN: 1530-0293 ISO Abbreviation: Crit. Care Med. Publication Date: 2010 Feb |
Date Detail:
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Created Date: 2010-01-19 Completed Date: 2010-02-22 Revised Date: - |
Medline Journal Info:
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Nlm Unique ID: 0355501 Medline TA: Crit Care Med Country: United States |
Other Details:
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Languages: eng Pagination: 510-7 Citation Subset: AIM; IM |
Affiliation:
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Department of Cardiology, Belfast Heart Centre, Royal Victoria Hospital, Belfast, Northern Ireland. nacromie@doctors.org.uk |
Export Citation:
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| MeSH Terms | |
Descriptor/Qualifier:
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Adult Aged Aged, 80 and over Cardiac Output Cardiography, Impedance / standards* Defibrillators / standards* Electrocardiography Female Heart Arrest / diagnosis, physiopathology* Heart Massage / methods Humans Male Middle Aged Myocardial Perfusion Imaging Sensitivity and Specificity Stroke Volume / physiology |
| Comments/Corrections | |
Comment In:
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Crit Care Med. 2010 Feb;38(2):712-3
[PMID:
20083940
]
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From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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