American journal of respiratory and critical care medicine
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Am. J. Respir. Crit. Care Med. · Aug 1998
The tension-time index and the frequency/tidal volume ratio are the major pathophysiologic determinants of weaning failure and success.
We have previously shown (Am. J. Respir. ⋯ To clarify on pathophysiologic grounds what determines inability to wean from mechanical ventilation, we performed multiple logistic regression analysis with the weaning outcome as the dependent variable. The TTI and the f/VT ratio were the only significant variables in the model. We conclude that the TTI and the f/VT are the major pathophysiologic determinants underlying the transition from weaning failure to weaning success.
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Am. J. Respir. Crit. Care Med. · Aug 1998
Defective motor control of coughing in Parkinson's disease.
The high incidence of serious chest infections in patients with Parkinson's disease is unexplained, but an impairment in cough reflex may have a role. Maximal voluntary cough (MVC) and reflex cough (RC) to inhalation of ultrasonically nebulized distilled water were analyzed in patients with Parkinson's disease and age-matched control subjects by monitoring the integrated electromyographic activity (IEMG) of abdominal muscles. The peak amplitude of IEMG activity (IEMGP) was expressed as a fraction of the highest IEMGP value observed during MVC corrected to account for possible losses in abdominal muscle force due to reduced central muscle activation. ⋯ Consequently, the rate of rise of IEMG activity during cough was always lower in patients (p < 0. 01), especially during RC. Finally, PEmax, and both the peak and rate of rise of IEMG activity during RC were inversely related to the level of clinical disability (Spearman rank correlation coefficient, rs = -0.88, -0.86, and -0.85, respectively, p always < 0.01). The results indicate that the central neural mechanisms subserving the recruitment of motor units and/or the increase in their frequency of discharge during voluntary and, even more markedly, RC are impaired in patients with Parkinson's disease.
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Am. J. Respir. Crit. Care Med. · Aug 1998
Development of a disease-specific health-related quality of life questionnaire for sleep apnea.
The Calgary Sleep Apnea Quality of Life Index (SAQLI) was developed to record key elements of the disease that are important to patients. All items felt to influence the quality of life of these patients were identified. Final questionnaire items were selected by interviewing 113 patients with sleep apnea and 50 snorers who rated each item on whether it was a problem and the importance of it to their overall quality of life. ⋯ It includes items shown to be important to patients with sleep apnea and is designed as a measure of outcome in clinical trials in sleep apnea. Flemons WW, Reimer MA. Development of a disease-specific health-related quality of life questionnaire for sleep apnea.
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Am. J. Respir. Crit. Care Med. · Jul 1998
Acute respiratory distress syndrome caused by pulmonary and extrapulmonary disease. Different syndromes?
To assess the possible differences in respiratory mechanics between the acute respiratory distress syndrome (ARDS) originating from pulmonary disease (ARDSp) and that originating from extrapulmonary disease (ARDSexp) we measured the total respiratory system (Est,rs), chest wall (Est,w) and lung (Est,L) elastance, the intra-abdominal pressure (IAP), and the end-expiratory lung volume (EELV) at 0, 5, 10, and 15 cm H2O positive end-expiratory pressure (PEEP) in 12 patients with ARDSp and nine with ARDSexp. At zero end-expiratory pressure (ZEEP), Est,rs and EELV were similar in both groups of patients. The Est,L, however, was markedly higher in the ARDSp group than in the ARDSexp group (20.2 +/- 5.4 versus 13.8 +/- 5.0 cm H2O/L, p < 0.05), whereas Est,w was abnormally increased in the ARDSexp group (12.1 +/- 3.8 versus 5.2 +/- 1.9 cm H2O/L, p < 0.05). ⋯ Increasing PEEP to 15 cm H2O caused an increase of Est,rs in ARDSp (from 25.4 +/- 6.2 to 31.2 +/- 11.3 cm H2O/L, p < 0.01) and a decrease in ARDSexp (from 25.9 +/- 5.4 to 21.4 +/- 55.5 cm H2O/L, p < 0.01). The estimated recruitment at 15 cm H2O PEEP was -0.031 +/- 0.092 versus 0.293 +/- 0.241 L in ARDSp and ARDSexp, respectively (p < 0.01). The different respiratory mechanics and response to PEEP observed are consistent with a prevalence of consolidation in ARDSp as opposed to prevalent edema and alveolar collapse in ARDSexp.
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Am. J. Respir. Crit. Care Med. · Jul 1998
Involvement of tachykinin NK3 receptors in citric acid-induced cough and bronchial responses in guinea pigs.
Aerosolized citric acid induces several pulmonary effects including bronchoconstriction, airway inflammation, and cough. Evidence from the use of tachykinin NK1 and NK2 receptor antagonists, as well as chronic treatment with high doses of capsaicin, have suggested that these effects are mediated through the release of tachykinins from sensory nerve endings. In the present study, we have investigated the effects of a tachykinin NK3 receptor antagonist, SR 142801 (osanetant), on cough, bronchoconstriction, and bronchial hyperresponsiveness induced by aerosolized citric acid (0.4 M) in guinea pigs. ⋯ A microvascular leakage hypersensitivity also occurred and was demonstrated by a potentiation of the plasma protein extravasation from bronchial vessels induced by histamine. When given once intraperitoneally at 1 mg . kg-1 30 min before the citric acid exposure, SR 142801 inhibited both hyperresponsiveness to acetylcholine and the potentiation of histamine-induced increase in microvascular permeability. The results suggest that tachykinin NK3 receptors are involved in citric acid-induced effects on airways.