Dear Editor

We read with interest the article “Noise levels within the ear and post-nasal space in neonates in Intensive care” by SS Surenthiran et al.[1] The article makes neonatal care providers conscious of the respiratory support generated turbulence of air in the post nasal space with potentially dangerous high levels of noise. Therefore, the article has potential to change the attitude of neonatal ventilatory support providers with long term neonatal benefits . However, we wish to seek clarifications on following points which are of research relevance.

1. In this study all the babies were nursed inside incubator. As per study of Gupta V et al,[2] it is known that incubators of different make produce varying levels of noises. Therefore it is pertinent to know whether all babies were kept in the incubators of same or different make, and what were their baseline sound preserve levels (SPL). This will permit adjustment to external confounder.

2. The sound produced by CPAP which was nasal has been compared with conventional mechanical ventilation (CMV). It would be relevant for research analysis to know that how many babies were given CMV with Nasotracheal tube and how many with orotracheal tube? As the nasal endotracheal tube is likely to have more SPL in post nasal space than orotracheal tube.

3. The SPL of various flow rates has been analyzed for CPAP. It would be relevant to know the effects on SPL of flow variations during CMV.

We therefore, solicit author’s comments for more effective answer to such an important research question.

References

(1) Surenthiran S S, Wilbrham K, May J, Chant T, Emmerson AJB, Newton VE. Noise levels within the ear and post-nasal space in neonates in intensive care. Arch Dis Child Fetal Neonatal Ed 2003;88;F315-F318.

(2) Gupta V, Gupta G, Nair MNG, Soodan KS. Sound levels in NICU. (ICMR supported research Yr 2003, not yet published)