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ARTICLES: Lalit Bajaj, Carol G. Turner, and Joan Bothner A Randomized Trial of Home Oxygen Therapy From the Emergency Department for Acute Bronchiolitis Pediatrics 2006; 117: 633-640 [Abstract] [Full text] [PDF]

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What are we actually treating here?

Michael J Verive   (12 March 2006)

What are we actually treating here? 12 March 2006
Michael J Verive, Physician Sinai Children's Hospital Send letter to journal: Re: What are we actually treating here? mverive{at}yahoo.com Michael J Verive	This article introduces a great concept - home oxygen therapy for bronchiolitis rather than hospital admission and inpatient treatment. However, there are a few problems with the study, one more semantic in nature, and others that are more fundamental. The semantic issue is easy to discuss, as the study refers to "hypoxia" reflected by room-air saturations <= 87%. Hypoxia refers to tissue that is deficient in oxygen, while pulse oximetry estimates oxyhemoglobin saturation. The two are not synonymous, and in fact many individuals (particularly those with single-ventricle physiology) have far lower oxyhemoglobin saturations without tissue hypoxia. The confusion between hypoxia and hypoxemia is at the root of one of the fundamental problems with the study; treatment based on oxyhemoglobin saturation is treating the number, and not the patient. In fact, one of the references used for this study (Bergman AB. Pulse oximetry, good technology misapplied. Arch Pediatr Adolesc Med 2004; 158:594-595) confirms this notion. Treating the pulse ox may give a sense of comfort to the physician, but may result in unnecessary therapeutic interventions (at home or in the hospital). Another problem in the study is a bit more subtle; oxygen delivery by nasal cannula was administered at a mean flow rate of just under 0.5 liters per minute (range 0.125 - 1). Although these flow rates are unlikely to deliver very high oxygen concentrations in adults, the same flow rates in infants can achieve concentrations of > 40%. I'm fairly certain that few physicians would discharge any infant who required 40% oxygen (eg, using a venturi device). It was also not stated whether the home oxygen systems were humidified. Non-humidified oxygen at the higher flow rates may be injurious to mucous membranes, and may also inspissate nasal secretions, making them more difficult to suction, and more prone to cause obstruction. I applaud efforts to reduce hospitalization rates for infants and children who have mild, self-limited illnesses. However, let's be certain that we're not just treating numbers, no matter how innocuous our therapy is (or appears to be). Conflict of Interest: None declared