Provocation of aspiration reflexes and their effects on the pattern of cough and reflex apnea in cats.
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Aspiration reflexes (AspRs) manifesting as reflex spasmodic inspirations and their effects on motor pattern of tracheobronchial cough and reflex apnea were studied on 22 spontaneously breathing pentobarbitone-anesthetized cats. AspRs induced during cough inspiration enhanced peak inspiratory (P<0.01) and expiratory (P<0.02) esophageal pressures, amplitudes of diaphragm (P<0.01) and abdominal muscles (P<0.05) EMG activity, and prolonged the entire expiratory period (P<0.01) and total cycle duration (P<0.05) of cough. Transient inhibitions and splits of cough expiration frequently occurred with AspR within active cough expiratory period; however, cough spatiotemporal characteristics were not altered significantly. Sub-threshold nasopharyngeal stimulation failing to provoke AspR had no significant effects on coughing. Hering-Breuer inflation apnea was moderately prolonged by AspRs (20%; P<0.05), unlike the apnea produced by continual mechanical laryngeal stimulation. AspRs are inducible during tested behaviors interacting with their motor pattern. Central mechanisms involving pulmonary stretch receptor stimulation is suggested for modulation of cough and inflation apnea by AspR. (+info)
Excitability and rhythmicity of tracheobronchial cough is altered by aspiration reflex in cats.
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Effects of nasopharyngeal stimulation on excitability and rhythmicity of mechanically induced tracheobronchial cough were examined on 18 pentobarbitone anesthetized cats. After the 17.2+/-2.4 aspiration reflexes (AspRs), tracheobronchial stimulation evoked lower number of coughs (P<0.05) with longer latency to the diaphragm activation (P<0.02), compared to control. AspRs induced within "inter-cough" periods (motor quiescence between individual coughs; 3.3 AspRs per period) reduced cough number by 50% (P<0.01), shortened cough-related abdominal activity (P<0.02), prolonged inter-cough period (P<0.02), and the total cough cycle duration (P<0.05). Cough efforts occurred irregularly with very variable "inter-cough" distances and total cough cycle durations. The subthreshold nasopharyngeal stimulation (failing to evoke AspR) did not affect rhythmic coughing. AspRs induced during persisting post-stimulation coughs did not significantly reduce their number. Excitability and rhythmicity of mechanically induced tracheobronchial cough can be reduced by AspRs, but not by subthreshold nasopharyngeal stimulation. The suppressive effect of spasmodic inspirations on chronic cough is suggested. (+info)
Lateral-horizontal patient position and horizontal orientation of the endotracheal tube to prevent aspiration in adult surgical intensive care unit patients: a feasibility study.
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BACKGROUND: Recent data suggest that during mechanical ventilation the lateral-horizontal patient position (in which the endotracheal tube is horizontal) decreases the risk of ventilator-associated pneumonia, compared to the recommended semi-recumbent position (in which the endotracheal tube slopes downward into the trachea). We tested the feasibility of the lateral-horizontal patient position, measured the incidence of aspiration of gastric contents, and watched for any adverse effects related to the lateral-horizontal position. METHODS: Ten adult intensive care unit patients were ventilated for 64 hours in the standard semi-recumbent position, and ten for 12-24 hours in the lateral-horizontal position. Tracheal secretions were collected every 8 hours and every 4 hours, respectively, and tested for pepsin, which is a marker of gastric contents. We also recorded clinical, physiologic, and outcome variables. RESULTS: The patients remained stable during ventilation in the lateral-horizontal position, and no adverse events occurred. Pepsin was detected in the trachea of 7 semi-recumbent patients and in five of the lateral-horizontal patients (P = .32). The number of ventilator-free days was 8 days (range 0-21 days) in the semi-recumbent patients, versus 24 days (range 12-25 days) in the lateral-horizontal patients (P = .04). CONCLUSIONS: Implementing the lateral-horizontal position for 12-24 hours in adult intubated intensive care unit patients is feasible, and our patients had no adverse events. The incidence of aspiration of gastric contents in the lateral-horizontal position seems to be similar to that in the semi-recumbent position. (+info)
Quantitative videofluoroscopic analysis of penetration-aspiration in post-stroke patients.
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A review of the potential applications and controversies of non-invasive testing for biomarkers of aspiration in the lung transplant population.
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