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J Appl Physiol (1985). 2014 Dec 15;117(12):1478-85. doi: 10.1152/japplphysiol.00259.2014. Epub 2014 Oct 16.

Test of the Starling resistor model in the human upper airway during sleep.

Author information

1
Division of Sleep Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts; awellman@rics.bwh.harvard.edu.
2
Division of Sleep Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts;
3
Department of Anesthesia, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts;
4
Department of Engineering, Boston University, Boston, Massachusetts; and.
5
Institute of Public Health, University of Aarhus, Aarhus, Denmark.

Abstract

The human pharyngeal airway during sleep is conventionally modeled as a Starling resistor. However, inspiratory flow often decreases with increasing effort (negative effort dependence, NED) rather than remaining fixed as predicted by the Starling resistor model. In this study, we tested a major prediction of the Starling resistor model--that the resistance of the airway upstream from the site of collapse remains fixed during flow limitation. During flow limitation in 24 patients with sleep apnea, resistance at several points along the pharyngeal airway was measured using a pressure catheter with multiple sensors. Resistance between the nose and the site of collapse (the upstream segment) was measured before and after the onset of flow limitation to determine whether the upstream dimensions remained fixed (as predicted by the Starling resistor model) or narrowed (a violation of the Starling resistor model). The upstream resistance from early to mid inspiration increased considerably during flow limitation (by 35 ± 41 cmH2O · liter(-1) · s(-1), P < 0.001). However, there was a wide range of variability between patients, and the increase in upstream resistance was strongly correlated with the amount of NED (r = 0.75, P < 0.001). Therefore, patients with little NED exhibited little upstream narrowing (consistent with the Starling model), and patients with large NED exhibited large upstream narrowing (inconsistent with the Starling model). These findings support the idea that there is not a single model of pharyngeal collapse, but rather that different mechanisms may dominate in different patients. These differences could potentially be exploited for treatment selection.

KEYWORDS:

choke point; flow limitation; pharynx; sleep apnea; wave speed theory

PMID:
25324514
PMCID:
PMC4269684
DOI:
10.1152/japplphysiol.00259.2014
[Indexed for MEDLINE]
Free PMC Article

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