That phrase, which has been used to denote the urgency of early stroke treatment in adults, has been purloined by Marianne Thoresen and her colleagues for their article about the importance of timely hypothermia treatment, and now by me for this blog post.
The Bristol group have recently published a prospective cohort study detailing the treatment and outcomes of about 80 babies who were treated with brain cooling. The 65 survivors were examined and evaluated with Bayley scores at 18 to 20 months of age. Frequent readers of this blog will know of my great concerns that the Bayley is a poor predictor of long term functioning in very preterm babies. It does, however, seem to be more useful as a predictor of long term outcomes in the asphyxiated term infant, as confirmed both by the Coolcap study group and the NICHD trial group.
The Bristol group performed an initial analysis which showed that survivors had cooling initiated at an average of 180 minutes, so they then divided the babies into those cooled before and after 180 minutes of age. The babies cooled earlier had more severe grades of encephalopathy, slightly lower first hour pH and no other real clinical differences to the later cooled infants.
The early cooled babies had about the same number of deaths as the late (8 vs 7) and the same number of overall poor outcomes, but the motor scores on the Bayley were significantly better in the early cooled group, despite them having more stage 3 HIE.
This is entirely consistent with some data from animal models, and with a secondary analysis of the Coolcap trial which did not show a significant difference, but did show a trend to improved outcomes with earlier randomization. However there wasn’t much spread in the randomization times in any of the RCTs, when they were being done we still had a lot of work to do to get timely referrals, so there were few babies cooled in the first 3 hours, median times of randomization being 4 to 4.5 hours of age.
Cooling on transport has been studied and can be done safely if you institute simple protocols.
The simple message is that ‘time is brain’, cooling is quite safe if carefully monitored, and should be started as soon as possible in affected infants.