Quantitative pupillometry in comatose out-of-hospital cardiac arrest patients: A post-hoc analysis of the TTH48 trial.

BACKGROUND

Quantitative pupillometry is an objective method to examine pupil reaction and subsequently grade the response on a neurological pupil index (NPi) scale from 0 to 5. The aim of the present sub-study was to explore the long-term prognostic value of NPi in comatose out-of-hospital cardiac arrest patients undergoing targeted temperature management (TTM).

METHODS

This planned sub-study of the "Targeted temperature management for 48 versus 24 h and neurological outcome after out-of-hospital cardiac arrest: A randomized clinical trial." NPi was assessed from admission and throughout day 3 and linked to the Cerebral Performance Categories score at 6 months. We compared the prognostic performance of NPi in 65 patients randomized to a target temperature of 33 ± 1°C for 24 or 48 h.

RESULTS

The NPi values were not different between TTM groups (p > .05). When data were pooled, NPi was strongly associated with neurological outcome at day 1 with a mean NPi of 3.6 (95% CI 3.4-3.8) versus NPi 3.9 (3.6-4.1) in the poor versus good outcome group, respectively (p < .01). At day 2, NPi values were 3.6 (3.1-4.0) and 4.1 (3.9-4.2) (p = .01) and at day 3, the values were 3.3 (2.6-4.0) and 4.3 (4.1-4.6), respectively (p < .01). The prognostic ability of NPi, defined by area under the receiver operating characteristic curve was best at day three.

CONCLUSION

Quantitative pupillometry measured by NPi was not different in the two TTM groups, but overall, significantly associated with good and poor neurological outcomes at 6 months. NPI has a promising diagnostic accuracy, but larger studies are warranted.