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Crit Care Med. 2010 Aug;38(8):1709-17. doi: 10.1097/CCM.0b013e3181e7dd29.

Quantitative assessment of somatosensory-evoked potentials after cardiac arrest in rats: prognostication of functional outcomes.

Author information

1
Department of Biomedical Engineering, John Hopkins University School of Medicine, Baltimore, MD, USA.

Abstract

OBJECTIVE:

High incidence of poor neurologic sequelae after resuscitation from cardiac arrest underscores the need for objective electrophysiological markers for assessment and prognosis. This study aims to develop a novel marker based on somatosensory evoked potentials (SSEPs). Normal SSEPs involve thalamocortical circuits suggested to play a role in arousal. Due to the vulnerability of these circuits to hypoxic-ischemic insults, we hypothesize that quantitative SSEP markers may indicate future neurologic status.

DESIGN:

Laboratory investigation.

SETTING:

University Medical School and Animal Research Facility.

SUBJECTS:

: Sixteen adult male Wistar rats.

INTERVENTIONS:

None.

MEASUREMENTS AND MAIN RESULTS:

SSEPs were recorded during baseline, during the first 4 hrs, and at 24, 48, and 72 hrs postasphyxia from animals subjected to asphyxia-induced cardiac arrest for 7 or 9 mins (n = 8/group). Functional evaluation was performed using the Neurologic Deficit Score (NDS). For quantitative analysis, the phase space representation of the SSEPs-a plot of the signal vs. its slope-was used to compute the phase space area bounded by the waveforms recorded after injury and recovery. Phase space areas during the first 85-190 mins postasphyxia were significantly different between rats with good (72 hr NDS >or=50) and poor (72 hr NDS <50) outcomes (p = .02). Phase space area not only had a high outcome prediction accuracy (80-93%, p < .05) during 85-190 mins postasphyxia but also offered 78% sensitivity to good outcomes without compromising specificity (83-100%). A very early peak of SSEPs that precedes the primary somatosensory response was found to have a modest correlation with the 72 hr NDS subscores for thalamic and brainstem function (p = .066) and not with sensory-motor function (p = .30).

CONCLUSIONS:

Phase space area, a quantitative measure of the entire SSEP morphology, was shown to robustly track neurologic recovery after cardiac arrest. SSEPs are among the most reliable predictors of poor outcome after cardiac arrest; however, phase space area values early after resuscitation can enhance the ability to prognosticate not only poor but also good long-term neurologic outcomes.

Comment in

PMID:
20526197
PMCID:
PMC3050516
DOI:
10.1097/CCM.0b013e3181e7dd29
[Indexed for MEDLINE]
Free PMC Article
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