Sir,

I thank the authors for their interesting case series describing the use of ketamine sedation for the treatment of retinopathy of prematurity.1 I agree that no ideal agent exists but have reservations about the use of ketamine in this age group, which merits discussion.

There still remain questions over the potential neurotoxic effects of some anaesthetic agents in this age group, and ketamine has been the most strongly implicated in the debate.2 Volatile agents, midazolam, and ketamine can cause neuroapoptosis (programmed neuronal cell death) in the neonatal rat model, evidence which has concerned the Food and Drug Administration in the United States to instigate trials in a primate model.2 Exposure may result in adverse cognitive sequelae, but at present, the risk is difficult to quantify.2

Remifentanil has been shown to have predictable pharmacokinetics and pharmacodynamics in neonates, importantly an offset time similar to that of older children and adults.3 This allows early extubation, and can be used on a neonatal unit, negating the need for transfer to theatre.4, 5

Remifentanil is a unique opioid in neonatal practice and may be an ideal agent either alone or as a sedative in combination with Sub-Tenons block. As described, ketamine has significant potential disadvantages. I would suggest that more data are needed as well as careful consideration before recommending its widespread use in management of retinopathy of prematurity.