Respiration physiology
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Respiration physiology · Jan 2001
Effect of slow wave and REM sleep on thyropharyngeus and stylopharyngeus activity during induced central apneas.
The pharyngeal constrictors have been hypothesized to play an important role in the regulation of upper airway (UAW) patency in patients with sleep apnea. However, little research has focused on the activation and control of muscles that determine the lateral and posterior wall of the retropalatal airway dimensions. Our aim was to investigate the effects of slow wave sleep (SWS) and rapid eye movement (REM) sleep on the activation of pharyngeal constrictor (thyropharyngeus; TP) and dilator (stylopharyngeus; SP) muscles during eupneic breathing and induced central apneas. ⋯ During REM, TP and SP activity were not different from their reduced controls (P>0.02). The data supports our hypotheses that SWS and REM sleep causes a reduction in the eupneic TP and SP activity, as well as a reduction in TP response to induced apneas. However, the relative imbalance in TP vs SP activity during the recovery from an apnea (awake and SWS) suggest that an imbalance of active neuromuscular forces may contribute to upper airway narrowing in mixed apneas, but not in central apnea during sleep.
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Adult Respiratory Distress Syndrome is a disease with functional lung heterogeneity and thus a ventilator-delivered breath may over-distend non-involved areas. In rats we examined ventilator-delivered tidal volume (TV) breaths of 7 and 20 ml/kg on lung water as evidence of lung injury. We examined the role of aquaporins on ventilator-induced lung injury (VILI) by infusing HgCl(2) which inhibits aquaporins by binding cysteine. ⋯ Equimolar cysteine infusions prevented the HgCl(2) from increasing the W/D above that seen with TV 20 ml/kg. Thus ventilation with TV of 20 ml/kg produced a protein-rich lung edema. Aquaporin channels may have a protective effect in VILI.
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Respiration physiology · Oct 2000
Clinical TrialAcute hypoxia activates human 8-12 Hz physiological tremor.
Hypoxia causes arousal. Therefore, we hypothesized that hypoxia activates the human somatomotor system and should augment tremor. We determined the effects of hypoxia, PET(O2) = 45+/-2.2 mm Hg, hypocapnia, and the hypocapnic-hypoxic interaction on finger tremor during elastic loading. ⋯ Furthermore, six subjects (50%) exhibited significantly more tremor during hypocapnic hypoxia (hH) than during eucapnic hypoxia (eH). We conclude that acute hypoxia augments 8-12 Hz physiological tremor, and hypocapnia further augments this tremor in some subjects. As such, hypoxic tremor is activated physiological tremor, and entrainment of spinal alpha-motoneuron activity may be the final common pathway.
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Respiration physiology · Jun 1998
Effects of volatile anesthetics on vagal C-fiber activities and their reflexes in anesthetized dogs.
Effects of halothane, enflurane, isoflurane, and sevoflurane on vagal capsaicin (CAPS)-sensitive C-fibers were elucidated in anesthetized dogs. The CAPS-sensitive C-fibers were significantly stimulated by all volatile anesthetics with a significantly greater response to halothane than with sevoflurane. ⋯ The tachypnea induced by halothane, isoflurane, and sevoflurane was significantly reduced or no longer observed after perineural CAPS-treatment or bilateral vagotomy, whereas the slowing of respiration observed with enflurane was not affected by either of these treatments. These results suggest that vagal C-fibers play an important role in the reflex tachypnea that occurs with halothane, isoflurane, and sevoflurane.
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Respiration physiology · Feb 1998
Responses of laryngeal capsaicin-sensitive receptors to volatile anesthetics in anesthetized dogs.
The responses of laryngeal capsaicin (CAPS)-sensitive receptors to halothane, enflurane, isoflurane and sevoflurane were evaluated in anesthetized spontaneously breathing dogs from the afferent activity of the internal branch of the superior laryngeal nerve. The CAPS-sensitive receptors were clearly distinguished from irritant receptors by their responsiveness to CAPS and their lack of responsiveness to water. ⋯ In contrast, responses of irritant receptors to the volatile anesthetics were divided into three types (stimulation, inhibition or non-response), and did not differ among anesthetics. In conclusion, the present study demonstrated that the CAPS-sensitive receptors were consistently stimulated by halogenated volatile anesthetics and especially by halothane, enflurane, and isoflurane, and that these responses were dissimilar to the variable responses of irritant receptors.