Background Hypothermia is becoming a common treatment for newborns with hypoxic ischaemic encephalopathy. Cerebral metabolic effects have been studied extensively. However, acute effects on peripheral microcirculation are unknown. The effects of therapeutic hypothermia on peripheral microcirculation assessed by side-stream dark field (SDF) imaging technique are presented.

Methods Peripheral microcirculation was assessed in seven newborns undergoing selective head-cooling treatment with SDF imaging video recordings during core temperature 34°C, and then after re-warming at 37°C, and also in seven control patients with rectal temperature 37°C. Microvascular flow index (MFI) and per cent of vessels with sluggish flow were determined by using appropriate software.

Results Sluggish microcirculation was observed during hypothermia compared with controls. MFI and per cent of vessels with sluggish flow returned to normal after re-warming.

Conclusions The results of this small group of newborns going through therapeutic hypothermia suggests that microcirculation is effected with this treatment. Whether this finding has other clinical impacts requires further research.