We thank Murki and Sethuraman with their colleagues for their interest in our paper on bubbling CPAP. Both letters discuss variations of a theme and so we will respond to them together.

The first point made is that the system we describe is the same as that described by Gregory, et al. long back in 1971 and one which has now been discarded in favor of a CPAP apparatus that provides warmed, humidified oxygen and ‘stable pressure’. Indeed the authors are right, that the system we describe is not new. We have been using it in our hospital for over 10 years now. When we started, we used it rather apologetically as a poor man’s alternative, when more posh units were using the expensive CPAP machines giving ‘stable pressure.’ Then suddenly, America discovered ‘bubbling CPAP’ and the advantages that it brought. Instantly the old system became the state-of-the-art CPAP machine, vastly superior to the expensive system giving ‘stable pressure’. We are no longer apologetic about using bubbling CPAP and that is the context in which we sent our paper for publication. The message is simple - the inexpensive devise is superior to ‘stable pressure CPAP’ and even people working in resource poor settings can use it to save lives.

The correspondents say we have advocated use of bubble CPAP without saturation monitoring. This is not correct. We have said that bubble CPAP with air is safe and saturation monitoring is not required. This is true and we stand by what we wrote.

The correspondents suggest that only humidifiers provided with heating coils in the tubing must be used. Voltaire has written of the ‘best as the enemy of the good’- how by exalting only the ‘best’, we discourage other good solutions and lower the overall level of quality. Now that humidifiers and heating coils for the tubing are available, are we to say that doctors working in remote areas of India are not allowed to use oxygen from a cylinder unless they have all the equipment for providing it warmed and humidified at 37º C. In fact, even some of the older positive pressure ventilators we use in our unit do not have heating coils in the tubing but only condensation collection traps. It is pertinent here to point out that the latest Fisher and Paykel MR 810 (Aukland, New Zealand) humidifier we have bought does not even have a temperature read-out but it has 3 heat settings. One does not know when 37º C temperature is achieved. In contrast, the low cost humidifiers provided by Appropriate Technologies, Jan Swasthya Sahyoj (1626/33 First floor, Naiwala, Karol Bagh, New Delhi) has incorporated a temperature read-out for the heating chamber. We do not feel that heating wires for the tubing are crucial. The authors misunderstand the principle of primum-non-nocere. If the principle of do-no-harm were an absolute and overriding principle, one would never use antibiotics because we know there is a small chance of anaphylaxis and the possibility of death. The principle applies only to interventions where the chance of harm is more than the likelihood of benefit. Primum-non-nocere gives way to primum succurrere-‘first hasten to help,’ in most circumstances. In the context of using oxygen for a hypoxic child, to deny the child oxygen, just for want of a heating coil would be reprehensible.

Our correspondents write of the superiority of nasal prongs. This may well be true, but they are costly, not widely available, and the nasopharyngeal tube works well. There are two other points. Murki and colleague say that a FiO2 monitor costing Rs. 15000 to 25000 must be used if an expensive blender is not utilized. We disagree. The FiO2 monitor is not used in any CPAP system. It can be used to measure oxygen concentration in apparatus like the head box but not in-line, in ventilator tubings.

We hope that the simple, state-of-the-art apparatus we described can be used widely and that it will make a difference to the survival of babies.

Charanjit Kaur,
Jacob Puliyel,
Department of Pediatrics,
St Stephens Hospital,
Tis Hazari, Delhi 110 054,
India.
E-mail: [email protected]