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Sedation Confounds Outcome Prediction in Cardiac Arrest Survivors Treated with Hypothermia

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Abstract

Background

Therapeutic hypothermia is commonly used in comatose survivors’ post-cardiopulmonary resuscitation (CPR). It is unknown whether outcome predictors perform accurately after hypothermia treatment.

Methods

Post-CPR comatose survivors were prospectively enrolled. Six outcome predictors [pupillary and corneal reflexes, motor response to pain, and somatosensory-evoked potentials (SSEP) >72 h; status myoclonus, and serum neuron-specific enolase (NSE) levels <72 h] were systematically recorded. Poor outcome was defined as death or vegetative state at 3 months. Patients were considered “sedated” if they received any sedative drugs ≤12 h prior the 72 h neurological assessment.

Results

Of 85 prospectively enrolled patients, 53 (62%) underwent hypothermia. Furthermore, 53 of the 85 patients (62%) had a poor outcome. Baseline characteristics did not differ between the hypothermia and normothermia groups. Sedative drugs at 72 h were used in 62 (73%) patients overall, and more frequently in hypothermia than in normothermia patients: 83 versus 60% (P = 0.02). Status myoclonus <72 h, absent cortical responses by SSEPs >72 h, and absent pupillary reflexes >72 h predicted poor outcome with a 100% specificity both in hypothermia and normothermia patients. In contrast, absent corneal reflexes >72 h, motor response extensor or absent >72 h, and peak NSE >33 ng/ml <72 h predicted poor outcome with 100% specificity only in non-sedated patients, irrespective of prior treatment with hypothermia.

Conclusions

Sedative medications are commonly used in proximity of the 72-h neurological examination in comatose CPR survivors and are an important prognostication confounder. Patients treated with hypothermia are more likely to receive sedation than those who are not treated with hypothermia.

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Acknowledgments

The authors would like to thank Stephanie Kemp for administrative support for this study and Marion Buckwalter, Chitra Venkatasubramanian, Amie Hsia, Maarten Lansberg, Neil Schwartz, and Gregory Albers for their assistance with patient enrollment. Dr. Wijman has received funding from the following grants for this research: AHA Scientist Development Award, 043275N, and NIH RO1 HL089116-01A2.

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Authors and Affiliations

  1. Stanford University School of Medicine, Stanford University Medical Center, 780 Welch Road, Suite 205, Palo Alto, CA, 94304, USA

    Edgar A. Samaniego, Michael Mlynash, Anna Finley Caulfield, Irina Eyngorn & Christine A. C. Wijman

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  1. Edgar A. Samaniego
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  2. Michael Mlynash
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  3. Anna Finley Caulfield
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  5. Christine A. C. Wijman
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Corresponding author

Correspondence to Christine A. C. Wijman.

Additional information

The statistical analyses were conducted by Drs. Michael Mlynash and Edgar A. Samaniego.

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Samaniego, E.A., Mlynash, M., Caulfield, A.F. et al. Sedation Confounds Outcome Prediction in Cardiac Arrest Survivors Treated with Hypothermia. Neurocrit Care 15, 113–119 (2011). https://doi.org/10.1007/s12028-010-9412-8

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