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Mark E. Fenton, MD, FCCP; Karen Heathcote, MD; Rhonda Bryce, MD; Robert Skomro, MD, FCCP; John K. Reid, MD, FCCP; John Gjevre, MD, FCCP; David Cotton, MD, FCCP
Author and Funding Information

From the Division of Respirology, Critical Care and Sleep Medicine (Drs Fenton, Heathcote, Skomro, Reid, Gjevre, and Cotton) and Clinical Research Support Unit (Dr Bryce), University of Saskatchewan.

CORRESPONDENCE TO: Mark E. Fenton, MD, FCCP, Division of Respirology, Critical Care and Sleep Medicine, 5th Floor Ellis Hall, Royal University Hospital, 103 Hospital Dr, Saskatoon, SK, S7N 0W8, Canada; e-mail: mark.fenton@usask.ca

FINANCIAL/NONFINANCIAL DISCLOSURES: The authors have reported to CHEST that no potential conflicts of interest exist with any companies/organizations whose products or services may be discussed in this article.

Reproduction of this article is prohibited without written permission from the American College of Chest Physicians. See online for more details.

Chest. 2014;146(3):e113-e114. doi:10.1378/chest.14-1071
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To the Editor:

We thank Dr Hunasikatti for his interest in our recent article1 and his comments. The study was designed to evaluate whether the elbow sign can improve the pretest probability of OSA, and it clearly does. We are not advocating that, based on our single-center study, broad application of the elbow sign as an alternative to polysomnography (PSG) or other testing be implemented. Rather, we were merely pointing out the excellent operating characteristics of this simple clinical sign in obese men and its ability to improve pretest prediction in patients with lower pretest probabilities. The idea of it replacing PSG is intriguing and would need to be studied in a clinical trial with appropriate patient selection before being considered. As Dr Hunasikatti states, cost control is an important issue; however, we would also point out the benefit to an individual patient to avoid the inconvenience of a test. As in all areas of medicine, a PSG or level 3 test should be used to buttress the clinical impression of the physician. One could argue that there is little improvement to be made beyond a specificity of 97%. Tests should not be done just for the sake of doing them.

We are very well aware that sleep apnea is not a homogeneous disorder and have not advocated for autotitrating CPAP (autoCPAP) for everyone, as Dr Hunasikatti states. Additionally, we suggest that comparison with atrioventricular nodal ablation, an invasive procedure with the potential for arrhythmia and other serious morbidities, misses the mark, as CPAP is a fairly benign therapy with no serious side effects.

The possibility of central sleep apnea (CSA) in any patient being prescribed autoCPAP is a concern. In our center, for patients with clinical conditions predisposing to CSA (eg, heart failure), autoCPAP is routinely avoided in favor of PSG. Occasionally, patients without significant comorbidities who are diagnosed with OSA by PSG or level 3 test and prescribed autoCPAP experience CSA on treatment related to high loop gain. Identification of such patients prior to starting CPAP is currently impossible, regardless of the diagnostic test used. Hence, we would argue that such a patient receiving a diagnosis of OSA by the elbow sign and prescribed autoCPAP would be identified by the high residual apnea-hypopnea index and referred for a more definitive assessment of CSA by PSG. Furthermore, one could argue that such an algorithm would save patients time and inconvenience and reduce costs to the system by reserving PSG for such selected cases.

In summary, the elbow sign is a clinical tool that significantly improves the pretest prediction of OSA. However, it has not been validated as an alternative to PSG in the diagnosis of this disorder.


Fenton ME, Heathcote K, Bryce R, et al. The utility of the elbow sign in the diagnosis of OSA. Chest. 2014;145(3):518-524. [CrossRef] [PubMed]




Fenton ME, Heathcote K, Bryce R, et al. The utility of the elbow sign in the diagnosis of OSA. Chest. 2014;145(3):518-524. [CrossRef] [PubMed]
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