Skin sympathetic nerve activity as a biomarker for neurologic recovery during therapeutic hypothermia for cardiac arrest

BACKGROUND Targeted temperature management (TTM) improves neurologic outcome after cardiac arrest. However, better neurologic prognostication is needed. OBJECTIVE The purpose of this study was to test the hypothesis that noninvasive recording of skin sympathetic nerve activity (SKNA) and its association with heart rate (HR) during TTM may serve as a biomarker of neurologic status. METHODS SKNA recordings were analyzed from 29 patients undergoing TTM. Patients were grouped based on Clinical Performance Category (CPC) score into group 1 (CPC 1-2) representing a good neurologic outcome and group 2 (CPC 3-5) representing a poor neurologic outcome. RESULTS Of the 29 study participants, 18 (62%) were deemed to have poor neurologic outcome. At all timepoints, low average skin sympathetic nerve activity (aSKNA) was associated with poor neurologic outcome (odds ratio 22.69; P = .002) and remained significant (P = .03) even when adjusting for presenting clinical factors. The changes in aSKNA and HR during warming in group 1 were significantly correlated (rho = 0.49; P < .001), even when adjusting for corresponding temperature and mean arterial pressure measurements (P = .017), whereas this correlation was not observed in group 2. Corresponding to high aSKNA, there was increased nerve burst activity during warming in group 1 compared to group 2 (0.739 +/- 0.451 vs 0.176 +/- 0.231; P = .013). CONCLUSION Neurologic recovery was retrospectively associated with SKNA. Patients undergoing TTM who did not achieve neurologic recovery were associated with low SKNA and lacked a significant correlation between SKNA and HR. These preliminary results indicate that SKNA may potentially be a useful biomarker to predict neurologic status in patients undergoing TTM.

Automated summary

Neurologic recovery was associated with SKNA. Patients who did not achieve neurologic recovery during TTM were associated with low SKNA and lacked a significant correlation between SKNA and HR. Preliminary results suggest that SKNA may be a useful biomarker for predicting neurologic status in patients undergoing TTM.