The European respiratory journal : official journal of the European Society for Clinical Respiratory Physiology
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Comparative Study
Force-frequency relationships of in vivo human and in vitro rat diaphragm using paired stimuli.
Supramaximal stimuli, with time intervals of 100 ms (10 Hz) to 10 ms (100 Hz), were delivered in pairs to the phrenic nerves, bilaterally, in five seated normal subjects, while transdiaphragmatic pressure swings (Pdi,s) were recorded at relaxed end-expiratory lung volume with airways closed. In fresh diaphragms, Pdi,s increased between 10-20 Hz and reached a plateau between 20-30 Hz. Diaphragmatic fatigue decreased Pdi,s at all frequencies. ⋯ The ratio of T2 at 10 Hz over 100 Hz (T2(10/100)) thus decreased from 1.33 +/- 0.05 before fatigue to 0.97 +/- 0.12 after fatigue, and to 0.81 +/- 0.06 after 15 min rest. Similar results were obtained in isolated rat diaphragmatic strips stimulated and fatigued in vitro, from which we found a highly linear relationship (r = 0.94, p < 0.001) between the ratio of T2(10/100) and that of tetanic force at 10 Hz over 100 Hz (P10/100). We conclude that phrenic nerve paired twitches provide similar information when obtained from phrenic tetanic stimulation in terms of diaphragmatic contractility, and the decrease in T2(10/100) ratio indicates diaphragm low frequency fatigue.
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We wished to study how pleural effusion affects dynamic mechanics of the lung and the chest wall. We also determined if these changes could be reversed by deep lung inflations. Pleural effusion was produced by saline infusion into the pleural space. ⋯ Dynamic elastance and resistance of the chest wall were little affected by these procedures. Thus, pleural effusion can have significant effects on dynamic elastance and resistance of the respiratory system (ERS, RRS). The transient nature of the change in lung parameters after deep inflation suggests that therapies based on periodic lung inflations may be of little benefit to patients with this condition.
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Randomized Controlled Trial Multicenter Study Clinical Trial
Sequential treatment with low dose almitrine bismesylate in hypoxaemic chronic obstructive airways disease.
Daily dose schedules of 100-200 mg of almitrine bismesylate improve arterial blood gases in patients with hypoxaemic chronic obstructive airways disease (COPD) but dose related side effects are evident. In the present study, daily doses approximately half of those previously used were employed in a randomised double blind manner in 85 patients (age 35-79 years) with hypoxaemic COPD. After a one month period to check stability of arterial blood gases, patients were allocated to almitrine (A) or placebo (P) using an unequal code (60% A, 40% P). ⋯ After withdrawal of therapy arterial blood gases and spirometry reverted to pre-treatment levels, suggesting no permanent reversal of pathophysiology. Dose related side effects of breathlessness, indigestion and peripheral neuropathy were not observed. Nerve conduction studies revealed no difference in peripheral nerve dysfunction in hypoxaemic COPD between active and placebo therapy.(ABSTRACT TRUNCATED AT 250 WORDS)
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Randomized Controlled Trial Comparative Study Clinical Trial
Comparison of nebulized and sprayed topical anaesthesia for fibreoptic bronchoscopy.
We compared the efficacy of nebulized (N) and sprayed (S) topical anaesthesia prior to fibreoptic bronchoscopy in a blinded study involving 54 patients aged 57 +/- 26 yrs (mean +/- SD). Cough frequency, recorded on cassette tape, was the index of efficacy. All patients received 100 mg lignocaine sprayed into the pharynx, or nebulized in random order prior to bronchoscopy, and all received intravenous diazepam sedation. ⋯ Furthermore, no differences were found in cough frequency between N and S among smokers, patients with asthma and COPD, and patients who had a biopsy procedure, although a trend was seen in all comparisons towards a lower cough frequency with the nebulized route. Most patients in the S group found the spray unpleasant, whereas only one in the N group complained. We conclude that nebulized and sprayed lignocaine have similar efficacy as topical anaesthetics in fibreoptic bronchoscopy, but patient preference favours the nebulized route.
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Randomized Controlled Trial Clinical Trial
Influence of posture on mechanical parameters derived from respiratory impedance.
The influence of posture on respiratory mechanics was investigated in 10 healthy volunteers, using the forced pseudorandom noise technique. Subjects were studied in four randomly selected positions: sitting; sitting with the head turned sideways; supine; and prone with the head turned sideways. ⋯ R4 was significantly higher in the supine position than in either of the sitting or the prone positions. These results demonstrate that changes in lung volume cannot completely explain the influence of posture on respiratory resistance, and indicate upper airway geometry as a determinant factor of respiratory resistance.