Abstract
We evaluated the effect of posture on the sensitivity and specificity of abnormalities in the flow-volume loop in 30 patients with suspected obstructive sleep apnoea. Flow-volume loops were judged as abnormal if the FEF50/FIF50 ratio was greater than 1 or if the sawtooth sign was judged to be present by at least two of three chest physicians. Detailed nocturnal recordings confirmed the presence of obstructive sleep apnoea in 17 of the 30 patients. Our results showed that both the sensitivity and the specificity of each of the flow-volume criteria for the diagnosis of obstructive sleep apnoea were higher when the loops were recorded in the supine than when they were recorded in the sitting position. The sensitivities were low, however, even with the supine posture--sawtoothing 41% and FEF50/FIF50 ratio greater than 1 47%. The highest sensitivity (71%) was obtained by considering a positive result as being the presence of either of the abnormalities in either the sitting or the supine posture. This sensitivity of the flow-volume loop was too low to recommend it as a routine screening test for the diagnosis of obstructive sleep apnoea but the presence of the sawtooth sign had a high specificity (92%) for the diagnosis of obstructive sleep apnoea. Furthermore, there was a greater fall in oxygen saturation in patients with apnoea who had sawtoothing than in those without sawtoothing. The presence of the sawtooth sign should increase the suspicion of sleep apnoea and suggest the need for further investigation. The effect of posture on the occurrence of abnormalities in the flow-volume loop suggests that position alters the configuration of the upper airway.
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Selected References
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- Block A. J., Boysen P. G., Wynne J. W., Hunt L. A. Sleep apnea, hypopnea and oxygen desaturation in normal subjects. A strong male predominance. N Engl J Med. 1979 Mar 8;300(10):513–517. doi: 10.1056/NEJM197903083001001. [DOI] [PubMed] [Google Scholar]
- Haponik E. F., Bleecker E. R., Allen R. P., Smith P. L., Kaplan J. Abnormal inspiratory flow-volume curves in patients with sleep-disordered breathing. Am Rev Respir Dis. 1981 Nov;124(5):571–574. doi: 10.1164/arrd.1981.124.5.571. [DOI] [PubMed] [Google Scholar]
- Haponik E. F., Smith P. L., Bohlman M. E., Allen R. P., Goldman S. M., Bleecker E. R. Computerized tomography in obstructive sleep apnea. Correlation of airway size with physiology during sleep and wakefulness. Am Rev Respir Dis. 1983 Feb;127(2):221–226. doi: 10.1164/arrd.1983.127.2.221. [DOI] [PubMed] [Google Scholar]
- Haponik E. F., Smith P. L., Kaplan J., Bleecker E. R. Flow-volume curves and sleep-disordered breathing: therapeutic implications. Thorax. 1983 Aug;38(8):609–615. doi: 10.1136/thx.38.8.609. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Rotman H. H., Liss H. P., Weg J. G. Diagnosis of upper airway obstruction by pulmonary function testing. Chest. 1975 Dec;68(6):796–799. doi: 10.1378/chest.68.6.796. [DOI] [PubMed] [Google Scholar]
- Sanders M. H., Martin R. J., Pennock B. E., Rogers R. M. The detection of sleep apnea in the awake patient. The 'saw-tooth' sign. JAMA. 1981 Jun 19;245(23):2414–2418. [PubMed] [Google Scholar]
- Suratt P. M., Dee P., Atkinson R. L., Armstrong P., Wilhoit S. C. Fluoroscopic and computed tomographic features of the pharyngeal airway in obstructive sleep apnea. Am Rev Respir Dis. 1983 Apr;127(4):487–492. doi: 10.1164/arrd.1983.127.4.487. [DOI] [PubMed] [Google Scholar]
- Tammelin B. R., Wilson A. F., Borowiecki B. B., Sassin J. F. Flow-volume curves reflect pharyngeal airway abnormalities in sleep apnea syndrome. Am Rev Respir Dis. 1983 Oct;128(4):712–715. doi: 10.1164/arrd.1983.128.4.712. [DOI] [PubMed] [Google Scholar]