SSEP in Therapeutic Hypothermia Era

Area of Science:

• Neurology
• Critical Care Medicine
• Neurophysiology

Background:

• Therapeutic hypothermia (TH) improves outcomes for comatose cardiac arrest survivors.
• The prognostic value of somatosensory evoked potentials (SSEPs) during TH is debated.
• Reliable predictors of neurological outcome are crucial for guiding patient management.

Purpose of the Study:

• To evaluate the reliability of SSEPs, specifically the N20 cortical response, in predicting neurological outcome in comatose cardiac arrest survivors treated with TH.
• To determine if the absence of N20 responses is a reliable indicator of poor outcome (non-awakening).

Main Methods:

• Retrospective review of 73 cardiac arrest survivors treated with TH from 2010-2013.
• SSEPs, including N20 responses, were analyzed at various time points.
• Neurological outcome was assessed using the Cerebral Performance Category (CPC) scale at discharge.

Main Results:

• Ninety-three SSEP studies were analyzed.
• Fourteen patients with absent N20 responses all had poor outcomes (CPC 4-5).
• Eleven patients had absent N20 responses during hypothermia; 3 remained absent post-rewarming.
• Technical artifacts affected 11.4% of SSEPs during cooling.

Conclusions:

• SSEPs remain a reliable prognostic tool in patients undergoing TH.
• Interpreting SSEPs during cooling requires caution due to technical challenges and potential self-fulfilling prophecy.
• Further prospective, multicenter studies are needed to validate SSEP reliability during and after TH.