Dear Editor,

It was with great interest that we read the article by Choong et al. - Remifentanil for endotracheal intubation in neonates: a randomised controlled trial. First of all, we would like to congratulate the authors for their relevant RCT. However, there are some aspects that should be pointed out. The premedication protocol for endotracheal intubation of this study includes many classes of drugs besides opioids that might interfere with physiological responses. For instance, the administration of succinylcoline (a short action muscle relaxant) might have biased the results. Indeed, premedication with succinylcoline could be able to influence the evaluation of intubation conditions by intubators. Since both groups received atropine, the pharmacodynamic responses were probably more influenced by this drug than by the opioids themselves. It should have been more appropriate if the comparison had included only the opioids (remifentanil versus fentanyl). Another issue is the evaluation of intubation conditions per se. The use of subjective impression of intubation rather than specific and validated scores1 seems to be not the ideal approach. In addition, the enrollment of six different intubators instead of just one2 could also have influenced this evaluation. The authors did not show any sample size calculation to support one of the outcomes (adverse events) and also one of the main conclusions of this trial. Even though, no differences in adverse events were detected in the comparison between groups. However, the study suggested that remifentanil was more frequently responsible for chest wall rigidity. To date, synthetic opioid administration as a cause of chest wall rigidity in adults has been recently questioned3. The general idea is that the opioids produce transient vocal cord closure rather than chest wall rigidity and this phenomenon could also happen with neonates. In this regard, succinylcoline administration might again avoid this adverse event in the group treated with fentanyl.4 Finally, the experience with remifentanil in neonates is not large enough and the RCTs with this opioid are very important. Indeed, the American Academy of Pediatrics has recently recommended the use of remifentanil as a possible premedication for neonatal endotracheal intubation.5,6 However, further properly designed and larger clinical trials are needed before any conclusion concerning the best opioid recommended for neonatal intubation.

Yerkes Pereira e Silva, MD, PhD; Juliana Marcatto, RN; Rosilu Barbosa, MD, MSc; Ana Cristina Simoes e Silva, MD, PhD

1- Viby-Mogensen J, Engbaek J, Eriksson LI et al. Good clinical research practice (GCRP) in pharmacodynamic studies of neuromuscular blocking agents. Acta Anaesthesiol Scand 1996;40:59-74.

2- E Silva Y, Gomez R, de Oliveira Marcatto J, et al. Morphine versus remifentanil for intubating preterm neonates. Arch Dis Child Fetal Neonatal Ed 2007;18:176-83.

3- Bennett JA, Abrams JT, Van Riper DF, et al. Difficult or impossible ventilation after sufentanil-induced anesthesia is caused primarily by vocal cord closure. Anesthesiology 1997;87:1070-1074.

4- Fahnenstich H, Steffan J, Kau N et al. Fentanyl induced chest wall rigidity and laryngospasm in preterm and term infants. Crit Care Med, 2000;28:836-839.

5- Kumar P, Denson, SE, Mancuso TJ and Committee of Fetus and Newborn, Section on Anesthesiology and Pain Medicine. Pediatrics 2010;125;608-615.

6- Greenwood CS, Colby CE. Pharmacology Review: Premedication for endotracheal intubation of the neonate: What is the evidence? NeoReviews 2009;10:e31-e35

Conflict of Interest:

None declared