Journal of applied physiology
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Numerous studies have demonstrated upper-airway neuromuscular abnormalities during wakefulness in snorers and obstructive sleep apnea (OSA) patients. However, the functional role of sensorimotor impairment in OSA pathogenesis/disease progression and its potential effects on protective upper-airway reflexes, measures of respiratory sensory processing, and force characteristics remain unclear. This study aimed to gain physiological insight into the potential role of sensorimotor impairment in OSA pathogenesis/disease progression by comparing sensory processing properties (respiratory-related evoked potentials; RREP), functionally important protective reflexes (genioglossus and tensor palatini) across a range of negative pressures (brief pulses and entrained iron lung ventilation), and tongue force and time to task failure characteristics between 12 untreated OSA patients and 13 controls. ⋯ Upper-airway protective reflexes across a range of negative pressures as measured by electromyography and the early P1 component of the RREP are preserved in OSA patients during wakefulness. Consistent with an adaptive training effect, tongue protrusion force is increased, not decreased, in untreated OSA patients. However, OSA patients may be vulnerable to fatigue of upper-airway dilator muscles, which could contribute to disease progression.
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The purpose of this study was to test the hypotheses that digital infrared thermographic imaging (DITI) during simulated uncontrolled hemorrhage will reveal 1) respiratory rate and 2) changes of skin temperature that track reductions of stroke volume. In 45 healthy volunteers (25 men and 20 women), we recorded the ECG, finger photoplethysmographic arterial pressure, respiratory rate (pneumobelt and DITI of the nose), cardiac output (inert rebreathing), and skin temperature of the forehead during lower body negative pressure (LBNP) at three continuous decompression rates; slow (-3 mmHg/min), medium (-6 mmHg/min), and fast (-12 mmHg/min) to an ending pressure of -60 mmHg. Respiratory rates calculated from the pneumobelt (14.7 ± 0.9 breaths/min) and DITI (14.9 ± 1.2 breaths/min) were not different (P = 0.21). ⋯ Our results suggest that a thermographic camera may prove useful for the remote assessment of traumatically injured patients. Life sign detection may be determined by verifying respiratory rate. Determining the magnitude and rate of hemorrhage may also be possible based on future algorithms derived from associations between skin temperature and stroke volume.