Light reflexes during CPR may indicate survival chances

By Ingrid Grasmo

The presence of the papillary light reflex (PLR) during cardiopulmonary resuscitation (CPR) is associated with early survival and favorable neurologic status during recovery, suggest findings from a case series.

"Accurate assessment of brain function during resuscitation would be valuable, as corrective action based on measurements of circulation or brain function might decrease the presence of severe neurological deficits in patients who survive," say Merlin Larson (University of California, San Francisco, USA) and co-authors.

For the study, which appears in Resuscitation, the researchers used infrared pupillometry to measure light reflexes in 30 patients with in-hospital cardiopulmonary arrest. Resuscitation attempts lasted a median of 11 minutes, with an average 1.9-minute interval between PLR measurements.

The PLR was detectable in 83% of patients. No initial PLR was observed in eight patients, but was recovered in less than 5 minutes. The average pupil size observed in patients with a PLR was 4.3 mm compared with 4.7 mm in patients with no PLR.

Return of spontaneous circulation (ROSC) was achieved in 20 patients, of whom 10 were still alive after 72 hours. In total, 13 patients achieved ROSC but showed poor outcomes, while the remaining seven were free of neurologic deficits on the third postarrest day.

The researchers note that patients who had favorable neurologic outcomes after 72 hours typically had increasing amplitude of the light reflex during CPR, which was either present throughout or absent for less than 5 minutes. Conversely, among patients who did not survive, light reflexes were either already absent or decreased in amplitude until they were absent.

Regression analysis showed that presence of the PLR significantly predicted early survival from resuscitation, and was a very good predictor for a favorable neurologic outcome among patients who survived for at least 72 hours after resuscitation.

The administration of adrenaline, atropine, or muscle relaxants did not block the light reflex.

In an associated editorial, Jack Breckwoldt (Charite University Medicine Berlin, Germany) and co-authors describe infrared pupillometry as "an objective tool which may help to avoid premature termination of CPR," but stress that, although predictive for poor outcomes, the absence of the PLR is not sufficient reason to call a halt to CPR.

They also note that the findings need to be verified in a much larger population, ideally involving patients with out-of-hospital cardiac arrest.

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