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Biomedical subjects

Federico Lavorini

Publications and source records attributed to Federico Lavorini.

8 recordsLinked to original sources
PubMed2006

Cough and ventilatory adjustments evoked by aerosolised capsaicin and distilled water (fog) in man.

Airway receptors mediate cough and ventilatory adjustments. Simultaneous assessment of cough sensory-motor components and changes in breathing pattern may provide insights into the receptor(s) prevailingly stimulated by inhaled irritants. Nineteen subjects inhaled capsaicin and fog up to threshold concentrations for cough. Cough intensity, respiratory sensations and changes in breathing pattern induced by the two irritants were compared. Capsaicin and fog cough threshold values did not correlate. Coughing induced by both agents was preceded by qualitatively similar sensations and by significant increases in minute ventilation and respiratory drive due to selective increases in tidal volume (P<0.01). Cough intensity was similar with both agents. Cough frequency and the intensity of the urge to cough were higher with capsaicin (P<0.01). The lack of correlation between fog and capsaicin cough threshold values suggests differences in the neural mechanisms activated. The selective increase in tidal volume suggests prevailing involvement of rapidly adapting receptors. The stronger sensations evoked by capsaicin may contribute to the higher cough frequency observed with this agent.

Adult↗
PubMed2006

Cough motor mechanisms.

Cough is a defensive airway mechanisms which involves the sequential activation of several laryngeal and respiratory muscles in the generation of the typical four-phase motor pattern. Activation of such muscles can be considered to represent the "primary" cough motor mechanism, and its functional significance, although complex, appears to be fairly well established. Nonetheless, the outflows of cough are numerous, and may additionally involve the reflex or mechanical activation of other respiratory and non-respiratory motor systems. These additional, or "secondary", outflows of cough can mainly be regarded as being involved in either enhancing the defensive function of cough, or opposing the possible noxious effects exerted by the mechanical stresses of coughing. In addition, both the primary and secondary cough motor mechanisms are known to play multiple functional roles, thus considerably complicating the cough panorama. Finally, some of the secondary cough motor responses, such as the changes in the pattern of breathing, seem to be devoid of any favourable action and their functional meaning, if any, is not fully understood. Although it is well known that all patterns of cough can be produced voluntarily, the extent to which also volitional cough is accompanied by an array of motor responses similar to that of reflex cough remains to be elucidated.

Animals↗
PubMed2006

Speed of onset of bronchodilator response to salbutamol inhaled via different devices in asthmatics: a bioassay based on functional antagonism.

AIMS: To evaluate the speed of onset of bronchodilation following salbutamol administered via a metered-dose inhaler with a spacer (pMDI + Volumatic) and a dry-powder inhaler (Diskus), as well as the relative potencies of these devices in asthmatic patients with methacholine-induced bronchoconstriction. METHODS: Eighteen patients inhaled methacholine (MCh) until FEV(1) decreased by 35% of control. Following administration of placebo, 200 microg salbutamol or 400 microg salbutamol through the pMDI + Volumatic or the Diskus, we calculated the time elapsed from drug administration and the appearance of a 90% increase in post-MCh forced vital capacity (FVC), FEV(1) and volume-adjusted mid-expiratory flow (recovery times). The salbutamol doses to be delivered by the two inhalation devices to achieve similar recovery times and the relative potencies of the devices were calculated by using the 2-by-2 Finney parallel regression method. RESULTS: For all functional variables, recovery times were significantly (P < 0.01) shorter in pMDI + Volumatic than Diskus trials. The salbutamol doses to be delivered by the Diskus to achieve recovery times for FVC, FEV(1) and volume-adjusted mid-expiratory flow similar to those obtained with 200 microg salbutamol administered via the pMDI + Volumatic were 558 (95% CI 537, 579) microg, 395 (95% CI 388, 404) microg and 404 (95% CI 393, 415) microg, respectively, and corresponded to relative potencies of 2.79 (95% CI 2.68, 2.90), 1.98 (95% CI 1.94, 2.02), and 2.02 (95% CI 1.96, 2.07). CONCLUSIONS: Administration of salbutamol via the pMDI + Volumatic provides faster reversal of induced bronchoconstriction than via the Diskus. The salbutamol dose targeting the lungs with the pMDI + Volumatic is approximately twice that with the Diskus.

Administration, Inhalation↗
PubMed2004

Cough in children with congenital central hypoventilation syndrome.

Congenital central hypoventilation syndrome (CCHS) is defined as failure of the chemical (autonomic) control of breathing causing alveolar hypoventilation in the absence of pulmonary, cardiac, neuromuscular or patent brainstem lesions. Hypoventilation is predominant in non-rapid-eye-movement sleep, during which breathing is primarily under chemical control. Failure of the central integration of chemosensory inputs is proposed as the putative defect. A genetic basis for CCHS is supported by lines of evidence. In some diseases of the central nervous system there is more or less complete depression of the cough reflex, whereas spontaneous ventilation is generally preserved. Little is known regarding cough in CCHS patients. Parents consistently report that their children cough 'normally' during airway infections; in contrast, experimental lines of evidence suggest that CCHS children lack a cough response following inhalation of a tussigenic agent. Although several factors may account for the discrepancy, the possibility of a weakened or even absent cough reflex remains to be fully ascertained. Conceivably, a defective cough reflex, in conjunction with the well established lack of perception of respiratory discomfort, might result in an increased risk of potentially serious respiratory complications in CCHS patients.

Central Nervous System Diseases↗
PubMed2004

Clinical and functional responses to salbutamol inhaled via different devices in asthmatic patients with induced bronchoconstriction.

AIMS: This study aimed at evaluating changes in airway patency, lung volumes and perception of breathing discomfort intensity following salbutamol administration via the Diskus dry-powder inhaler (DPI) or a pressurized metered-dose inhaler with the Volumatic valved holding chamber (pMDI + Volumatic) in asthmatic patients with methacholine-induced bronchoconstriction. METHODS: On six different study days, 18 patients inhaled methacholine until forced expiratory volume in 1 s (FEV(1)) decreased by approximately 35% of baseline. Following placebo, 200 and 400 microg of salbutamol through the pMDI + Volumatic or the Diskus, changes in FEV(1), volume-adjusted mean forced expiratory flow from 25 to 75% of the forced vital capacity (isoFEF(25-75)), lung volumes and breathing discomfort intensity, assessed by visual analogue scale (VAS) score, were repeatedly measured over a 60-min observation period. RESULTS: Induced bronchoconstriction was accompanied by obvious reductions in lung volumes and increases in VAS score. After salbutamol administration, FEV(1) and VAS score changes were similar in all experimental conditions. However, following 400 microg salbutamol via pMDI + Volumatic, isoFEF(25-75) values increased up to 4.48 l s(-1) (95% confidence interval 4.06, 4.90), a significantly (P < 0.01) higher value than those attained in all other experimental conditions. Independently of the salbutamol dose, lung volumes rose to significantly (P < 0.01) higher levels in pMDI + Volumatic than in Diskus trials. The low salbutamol dose via the pMDI + Volumatic and the high dose via the DPI increased isoFEF(25-75) and lung volumes to similar extents. CONCLUSIONS: Salbutamol via the pMDI + Volumatic provides greater isoFEF(25-75) and lung volume increases in asthmatic patients with induced bronchoconstriction; salbutamol-induced changes in VAS scores poorly reflect those in small airway patency. The lack of differences in FEV(1) increases observed after 200 and 400 microg salbutamol may reflect attainment of the flat portion of the dose-response curve using either device.

Administration, Inhalation↗
PubMed2002

Water aerosols and cough.

Inhalation of ultrasonically nebulised distilled water (fog) induces cough; however, the receptor type(s) mediating this reflex are poorly defined. In humans, cough threshold can be determined by inhalation of progressively increasing fog concentrations; the intensity of the associated motor response can be indexed in terms of flow-related variables as well as of the peak and slope of the integrated electromyographic activity of the abdominal muscles. We have evaluated coughing in patients with Parkinson's disease who show a high incidence of serious chest infections. These patients turned out to have a normal cough threshold but reduced expiratory muscle force during reflex coughing; this suggests an impairment in the central mechanisms subserving muscle activation possibly leading to inefficient airway clearing. Recurrent chest infections also affect laryngectomised patients. These patients have a normal cough threshold but reduced muscle force during coughing in response to threshold stimuli. Voluntary coughing is preserved in these patients, and this should be used to facilitate mucus removal. In normal subjects, fog inhalation causes cough and increases in respiratory drive and minute ventilation, mainly accounted for by increases in tidal volume, possibly due to activation of airway rapidly adapting receptors. Nedocromil sodium administration increases cough threshold and attenuates the ventilatory responses. The assessment of sensory and motor components of coughing may represent a useful tool for those investigating cough in humans.

Aerosols↗
PubMed2002

Handgrip-induced airway dilation in asthmatic patients with bronchoconstriction induced by MCh inhalation.

We investigated the effects of static and rhythmic handgrip on the time course of recovery of airway resistance measured with the interrupter technique (Rint) following bronchoconstriction induced by methacholine (MCh) inhalation in 17 asthmatic patients. On three separate occasions, a 100 +/- 5% increase in baseline Rint was induced by MCh inhalation. Subsequently, patients either rested [control trials (CTs)] or performed 3-min bouts of static or rhythmic handgrip. Respiratory and cardiovascular variables were continuously monitored. Rint changes were assessed at 1-min intervals for 30 min after rest and both types of handgrip. Plasma catecholamine concentrations were also determined at scheduled intervals. Bronchoconstriction increased ventilation (P < 0.01) but did not affect cardiovascular variables and plasma catecholamine concentrations. Handgrip provoked an increase in cardiovascular variables (P < 0.01) and plasma norepinephrine concentrations (P < 0.05) but caused no additional changes in ventilation. Rint only partially recovered within 30 min after CTs, whereas it consistently decreased 1 min after both handgrip paradigms and remained lower than after CTs (P always <0.01) for the whole 30-min observation period. Sympathetic activation and withdrawal of cholinergic input to the airway smooth muscle reflexly induced by activation of skeletal muscle and carotid sinus receptors may be the primary events accounting for the bronchodilator response induced by handgrip. Mediators co-released in response to sympathetic activation may also have contributed.

Administration, Inhalation↗