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PubMed2002

Neurochemical regulation of cough response to capsaicin in guinea-pigs.

1. Although monumental efforts have been made to define the action sites of cough, the importance of neurotransmitter systems in the cough reflex has received limited attention. We studied the roles for four major neurotransmitters [acetylcholine, histamine, serotonin (5-hydroxytryptamine, 5-HT) and dopamine] in the modulation of the cough reflex. 2. Atropine (muscarinic cholinergic blocking agent), pyrilamine maleate (PM, histamine H1 blocker), cimetidine (histamine H2 blocker), 8-hydroxy-2-(di-n-propylamino)-tetralin (8-OH-DPAT, specific 5-HT1A receptor agonist) and SCH-23390 (selective dopamine D1 receptor antagonist) were examined on the cough response to inhaled capsaicin in conscious guinea-pigs. 3. All the drugs significantly decreased the number of capsaicin-induced coughs in a dose-dependent manner. To compare the sensitivity of these drugs on cough response, we calculated the effective doses for 50% inhibition of cough (ED50) when the animals were exposed to 3 x 10-4 m capsaicin. The ED50 values were 0.03 microm kg-1 for atropine, 0.2 microm kg-1 for 8-OH-DPAT, 6.2 microm kg-1 for SCH-23390, 8.5 microm kg-1 for PM and 13.9 microm kg-1 for cimetidine. 4. These findings indicated that all these four neurotransmitters may be involved in the regulation of the cough reflex. Multiple changes of these neurotransmitters in disorders of the central nervous system might synergically affect the cough reflex.

Animals↗
PubMed2001

The ACE gene polymorphism and cough threshold for capsaicin after cilazapril usage.

Persistent dry cough is an occasional but clinically important adverse reaction to angiotensin I-converting enzyme (ACE) inhibitors (ACEI). Its reported incidence is variable, and why cough occurs in only certain individuals has been unclear. An insertion/deletion (I/D) polymorphism of the ACE gene is associated with serum ACE activity. We have previously shown that susceptibility to cough induced by ACEI is associated with this polymorphism such that patients with genotype II are more susceptible to cough than patients with other genotypes. In order to confirm and extend our previous observation, we conducted a randomized, placebo-controlled, double-blind, cross-over study in 10 healthy volunteers with genotype II and 10 with genotype DD. The cough threshold was determined by the concentration of inhaled capsaicin causing two or more coughs. After the usage of an ACEI, cilazapril, for 4 weeks, changes in the cough threshold in subjects with genotype II [before: 6.6+/-3.7 nM (mean+/-SD); after: 5.0+/-4.6 nM] significantly differed from those in subjects with genotype DD (before: 9.0+/-9.4 nM; after: 9.3+/-9.1 nM). Skin responses to intradermal bradykinin, which is a substrate of ACE and tussigenic, were significantly increased in subjects with genotype II (before: 1.6+/-0.6 vs. after: 2.6+/-0.5 cm2, P<0.05) but not in subjects with genotype DD (before: 1.4+/-0.5 vs. after: 1.6+/-0.6 cm2, n.s.) after usage of cilazapril. By contrast, skin responses to intradermal substance P did not change in subjects with either genotype. These findings provide further evidence of a link between ACEI-induced cough and I/D polymorphism of the ACE gene and suggest that ACEIs induce cough by modulating the tissue level of bradykinin.

Adult↗
PubMed2003

Eosinophilic bronchitis as a cause of chronic cough.

Eosinophilic bronchitis is a recently described condition in patients with chronic cough, sputum eosinophilia, normal spirometry and no evidence of bronchial hyperreactivity. The aim of the study was to assess the causes of chronic cough and to identify the prevalence of eosinophilic bronchitis as a cause of chronic cough. Thirty-six patients [mean age 45.4 +/- 14.3 years (range 16-69 years), M/F: 4/32] with an isolated chronic cough lasting for more than 4 weeks were recruited from the outpatient clinic. In all patients, after a full history and physical examination, blood eosinophil count, eosinophilic cationic protein (ECP), serum total and specific IgE levels were measured. Spirometry, methacholine provocation test, skin prick tests, ear, nose and throat examination, induction of sputum and esophageal pH testing were performed. The mean duration of cough was 31.3 +/- 52.3 months. Sputum eosinophilia greater than 3% was present in 12 (33.3%) patients and they were diagnosed as eosinophilic bronchitis. Their induced sputum had a mean eosinophil count of 8.3% and a mean ECP level of 98.5 mg x l(-1), which were higher than the others (P=0.003, both). The diagnosis of the remaining patients were postnasal drip syndrome in eight, gastroesophageal reflux disease in eight, post-infectious cough in two and cough-variant asthma in one patient. In conclusion, eosinophilic bronchitis is an important cause of chronic cough and should be considered in the assessment of patients before regarding them as having idiopathic chronic cough.

Adolescent↗
PubMed2001

[Tracheostomy valve with integrated cough flap for improving hands-free speech in laryngectomized patients--development and clinical applications].

BACKGROUND: Following successful voice restoration after laryngectomy either by a voice prosthesis, a surgical shunt or microvascular laryngoplasty, a further goal in rehabilitation is the insertion of a tracheostoma valve, which enables the patient to speak without using his fingers for closure of the tracheostoma. One important disadvantage of the tracheostoma valves, which are available today, is the necessity of removal of the valve in case of coughing, because the valve could be thrown from the stoma by the strong air flow during coughing. As many laryngectomies suffer from chronic bronchitis, this coughing problem is one of the reasons why only few patients could be provided with this useful aid. METHOD: At the department of biomedical engineering of the faculty of medicine at the university of Groningen, the Netherlands, 1994 two prototypes of a tracheostoma valve with an integrated cough lid were developed. These devices contain two separate valve systems: the normal speaking valve and a special coughing valve, which opens at a certain air flow and closes automatically after the coughing attack. Thus no manipulations are necessary during coughing, the patient can speak undisturbed. The ADEVA company (Lübeck, Germany) undertook the industrial production of this new type of tracheostoma valve creating different modifications of the prototype #2. PATIENTS: In four series with 6-8 patients per group the modified tracheostoma valves were tested clinically and the occurring faults or lack of correct function eliminated by small changes in the production. RESULTS: Meanwhile a suitable model for routine use is available, which was tested in 30 patients so far. This suitability was achieved by improvements in the valve mechanism, the valve seal and the adjustment mechanisms for the individual pressure level of the speaking and the coughing valve. CONCLUSION: The newly developed tracheostoma valve with integrated coughing lid (Window, ADEVA-medical Company, Lübeck, Germany) provides further improvement in speech rehabilitation of laryngectomies. The low acceptance of tracheostoma valves, which enable the patient to speak without using his fingers for closure of the tracheostoma, possibly may be raised by this new aid.

Bronchitis↗
PubMed1984

Relation of respiratory water loss to coughing after exercise.

Exercise has been shown to result in bronchoconstriction, the extent of which is related to respiratory heat loss. Some normal subjects report coughing after exercise, and to determine whether this might also be related to respiratory heat loss, we monitored cough frequency after hyperpnea with air of varying temperature and water content in seven such subjects. Hyperpnea with fully saturated air at 37 degrees failed to provoke coughing and was not associated with heat loss or water loss. Hyperpnea with dry air at 37 degrees C resulted in more water loss (P less than 0.0005), less heat loss (P less than 0.01), and more coughing (P less than 0.001) than hyperpnea with subfreezing air. Hyperpnea with ambient air was associated with a similar cough frequency and water loss but with less heat loss (P less than 0.001) than hyperpnea with subfreezing air. There was a direct relation between cough frequency and respiratory water loss but no consistent relation between cough frequency and respiratory heat loss. This study indicates that coughing after hyperpnea with poorly conditioned air is related to the overall rate of respiratory water loss. Since strenuous exercise is associated with marked hyperpnea, coughing after exercise may also result from respiratory water loss.

Adult↗
PubMed2002

Cough and bronchial responsiveness in firefighters at the World Trade Center site.

BACKGROUND: Workers from the Fire Department of New York City were exposed to a variety of inhaled materials during and after the collapse of the World Trade Center. We evaluated clinical features in a series of 332 firefighters in whom severe cough developed after exposure and the prevalence and severity of bronchial hyperreactivity in firefighters without severe cough classified according to the level of exposure. METHODS: "World Trade Center cough" was defined as a persistent cough that developed after exposure to the site and was accompanied by respiratory symptoms severe enough to require medical leave for at least four weeks. Evaluation of exposed firefighters included completion of a standard questionnaire, spirometry, airway-responsiveness testing, and chest imaging. RESULTS: In the first six months after September 11, 2001, World Trade Center cough occurred in 128 of 1636 firefighters with a high level of exposure (8 percent), 187 of 6958 with a moderate level of exposure (3 percent), and 17 of 1320 with a low level of exposure (1 percent). In addition, 95 percent had symptoms of dyspnea, 87 percent had gastroesophageal reflux disease, and 54 percent had nasal congestion. Of those tested before treatment of World Trade Center cough, 63 percent of firefighters (149 of 237) had a response to a bronchodilator and 24 percent (9 of 37) had bronchial hyperreactivity. Chest radiographs were unchanged from precollapse findings in 319 of the 332 with World Trade Center cough. Among the cohort without severe cough, bronchial hyperreactivity was present in 77 firefighters with a high level of exposure (23 percent) and 26 with a moderate level of exposure (8 percent). CONCLUSIONS: Intense, short-term exposure to materials generated during the collapse of the World Trade Center was associated with bronchial responsiveness and the development of cough. Clinical and physiological severity was related to the intensity of exposure.

Adult↗
PubMed2002

Antitussive effect of the leukotriene receptor antagonist zafirlukast in subjects with cough-variant asthma.

Cough-variant asthma (CVA) occurs in a subgroup of asthmatics whose sole or predominant respiratory symptom is cough. Although bronchodilators are often sufficient to treat CVA, refractory cough may require therapy with inhaled or systemic corticosteroids. In a randomized, double-blind, placebo-controlled, crossover study, we examined the effect of a 14-day course of the leukotriene receptor antagonist zafirlukast on subjective cough score and cough-reflex sensitivity to inhaled capsaicin in eight subjects with CVA refractory to inhaled beta agonists, and in five subjects refractory to inhaled corticosteroids. Seven of eight subjects experienced significant subjective and objective improvement in cough after treatment with zafirlukast. Mean (+/- SEM) cough score improved from 7.75 +/- 0.56 to 3.25 +/- 0.84 (p = 0.0006). Cough sensitivity to capsaicin was suppressed by zafirlukast in all subjects. Patients with CVA may represent a distinct subgroup of asthmatics whose afferent cough receptors within the respiratory epithelium are hypersensitive relative to those of patients with the typical form of asthma. Zafirlukast appears to be particularly effective in treating CVA by inhibiting the sensitivity of these receptors. Leukotriene receptor antagonists may offer an alternative to corticosteroids for the treatment of CVA refractory to inhaled bronchodilators.

Adult↗
PubMed2005

Assessment of the cough reflex after propofol anaesthesia for colonoscopy.

BACKGROUND: Dysfunction of the cough reflex as a result of the lingering effects of anaesthetics may lead to aspiration pneumonia or retained secretions after general anaesthesia. It is unknown whether low concentrations of propofol alter the cough reflex in the early period after anaesthesia. The objective of this study was to investigate the effect of low concentrations of propofol on the cough reflex sensitivity as assessed by the cough reflex threshold to an inhaled irritant. METHODS: Fifteen, ASA I-II, non-smoking patients undergoing elective colonoscopy were studied. Anaesthesia was induced and maintained with a blood target-controlled propofol infusion. Cough reflex threshold was measured with citric acid. Increasing concentrations of nebulized citric acid (2.5, 5, 10, 20, 40, 80, 160, 320, and 640 mg ml(-1)) were delivered during inspiration until a cough was evoked. The citric acid concentration eliciting one cough (C1) was defined as the cough reflex threshold. C1 was log transformed for statistical analysis (Log C1). Log C1 was measured before anaesthesia and during the recovery period with estimated decreasing propofol concentrations of 1.2, 0.9, 0.6, and 0.3 microg ml(-1). RESULTS: Log C1 (median; interquartile range) measured with propofol concentrations of 1.2, 0.9, 0.6, 0.3, and 0 microg ml(-1) were 1.9 (0.6), 1.9 (1.0), 1.9 (1.1), 1.9 (0.6), and 1.9 (0.7) mg ml(-1) (NS), respectively. However, light sedation was observed with propofol concentrations of 1.2 and 0.9 microg ml(-1). CONCLUSION: This study indicates that residual sedation after propofol anaesthesia for colonoscopy does not adversely affect the cough reflex.

Adult↗
PubMed2005

Autosomal dominant hereditary sensory neuropathy with chronic cough and gastro-oesophageal reflux: clinical features in two families linked to chromosome 3p22-p24.

Autosomal dominant hereditary sensory neuropathy (HSN I) is a clinically and genetically heterogeneous group of disorders, and in some families it is due to mutations in the serine palmitoyltransferase (SPTLC1) gene. We have characterized two families with HSN I associated with cough and gastro-oesophageal reflux (GOR). From a large Australian family, 27 individuals and from a smaller family, 11 individuals provided clinical information and blood for genetic analysis. Affected individuals had an adult onset of paroxysmal cough, GOR and distal sensory loss. Cough could be triggered by noxious odours or by pressure in the external auditory canal (Arnold's ear-cough reflex). Other features included throat clearing, hoarse voice, cough syncope and sensorineural hearing loss. Neurophysiological and pathological studies demonstrated a sensory axonal neuropathy. Gastric emptying studies were normal, and autonomic function and sweat tests were either normal or showed distal hypohidrosis. Cough was likely to be due to a combination of denervation hypersensitivity of the upper airways and oesophagus, and prominent GOR. Most affected individuals were shown on 24 h ambulatory oesophageal pH monitoring to have multiple episodes of GOR, closely temporally associated with coughing. Hoarse voice was probably attributable to acid-induced laryngeal damage, and there was no evidence of vocal cord palsy. No other cause for cough was found on most respiratory or otorhinological studies. Linkage to chromosome 3p22-p24 has been found in both families, with no evidence of linkage to loci for known HSN I, autosomal dominant hereditary motor and sensory neuropathy, hereditary GOR or triple A syndrome. These families represent a genetically novel variant of HSN I, with a distinctive cough owing to involvement of the upper aerodigestive tract.

Adult↗
PubMed1991

Cough and enalapril: assessment by spontaneous reporting and visual analogue scale under double-blind conditions.

The incidence and prevalence of cough related to enalapril was assessed by spontaneous reporting and a visual analogue scale during a 6 month random double-blind parallel-group study comparing enalapril with nifedipine. Cough was reported spontaneously by 6.2% of enalapril-treated patients, and by none on nifedipine (NS). No patient had to discontinue enalapril because of cough. After 24 weeks treatment increases in visual analogue scale scores for cough frequency greater than or equal to 8 mm were more common for enalapril than nifedipine (difference 21.5%, 95% CI 7.3-35.7%). Increased cough frequency by visual analogue scale was present throughout the study in women, but less consistently in men. High scores for cough were not related to the dose of enalapril. Cough with enalapril was not an important problem during the 6 months of treatment. However increased cough frequency could be detected by visual analogue scale, with a frequency consistent with that observed in open clinic-based studies of longer duration. These findings suggest that ACE inhibitor-induced cough may increase in severity over time, and that even a period of 6 months treatment is too short to evaluate this side-effect adequately.

Adult↗
PubMed1994

The effect of anticholinergic bronchodilator therapy on cough during upper respiratory tract infections.

1. Oxitropium bromide (Oxivent), an anticholinergic bronchodilator, inhibits coughing induced by hypotonic aerosols in both asthmatic and non-asthmatic individuals. We have now extended this work to investigate whether this antitussive activity is reproducible in cough associated with viral infection. 2. The effect of oxitropium bromide (200 micrograms three times daily) on cough and pulmonary function has been studied in 56 non-asthmatic volunteers with upper respiratory tract infections (URTI) in a double-blind, randomised, parallel group, placebo controlled study over 10 days. 3. Lung function, symptom questionnaire and cough response to ultrasonically nebulised distilled water (UNDW) inhalation were initially recorded within 72 h of development of cough and again after the 10 day treatment period. By use of a diary card at home, frequency and severity of cough, nocturnal symptoms and general malaise were assessed daily throughout the treatment period using 5 cm visual analogue scales (VAS). Peak expiratory flow rate (PEFR) was recorded thrice daily before treatment over this 10 day period. 4. VAS scores of symptoms and UNDW-induced cough frequency all decreased over the 10 days of observation whether oxitropium bromide or placebo was administered. The mean PEFR showed a statistically significant fall in morning values during the early stages of infection which lessened with recovery but no effect of treatment with oxitropium bromide was observed (P > 0.05). 5. Oxitropium bromide, which inhibits the cough response to UNDW, does not offer an effective therapy for cough associated with an upper respiratory tract viral infection.

Adolescent↗
PubMed2006

Paroxysmal coughing, subdural and retinal bleeding: a computer modelling approach.

Unexplained subdural and retinal haemorrhages in an infant are commonly attributed to 'shaking', the mechanism of which is believed to be traumatic venous rupture. However, the haemorrhagic retinopathy reported as a result of Valsalva manoeuvres and the subdural bleeding that is a rare complication of pertussis together demonstrate that if a sustained rise in intrathoracic pressure is transmitted to cerebral and retinal vessels, it may result in bleeding, similar to that reported in inflicted injury. Such haemorrhages would be expected to occur whenever severe paroxysmal coughing were induced, whatever the cause. This study used a computer modelling approach to investigate feeding accidents as the trigger for bleeding. A dynamic circulatory model of a 3-month-old infant was induced to 'cough', and the response to changes in physiological variables monitored. It showed that coughing causes intracranial pressures to build up exponentially to approach a maximum, proportional to the amount of pressure the musculature of the thorax can produce, as venous return is impeded. They do not have time to become dangerous during individual coughs, as blood quickly returns after the cough is over, reestablishing normal pressures. Paroxysmal coughing, however, does not allow blood to return between coughs, with the result that very high luminal pressures may be generated, sufficient to damage veins. A history of coughing, vomiting or choking is not uncommon in otherwise normal infants with retinal and subdural bleeding. Our findings suggest that paroxysmal coughing could account for such bleeding in some cases.

Brain↗
PubMed2006

A prospective longitudinal study of clinical characteristics, laboratory findings, diagnostic spectrum and outcomes of specific therapy in adult patients with chronic cough in a general respiratory clinic.

Chronic cough with established diagnostic protocols has been well described in secondary and tertiary centres. Little information is available about adult patients to a general respiratory clinic where no such protocols exist. The objective of this study is to determine clinical characteristics, laboratory findings, diagnostic spectrum and outcomes of specific therapy in adult patients with chronic cough in a general respiratory clinic. In this prospective, longitudinal, descriptive study for patients with chronic cough defined as more than 8 weeks, we studied, according to a questionnaire, chest radiography, spirometry and reversibility, methacholine challenge and other measures. Treatment was prescribed on the basis of diagnosis informed by investigation results.We evaluated 147 patients (102 females) of a mean age of 48 years and complaining of cough an average of 24 weeks. On the basis of a successful response to treatment, the causes of cough were determined in 92% and the frequencies were asthma in 39%, COPD in 11%, chronic upper airway cough syndrome (CUACS) in 9%, gastro-oesophageal reflux disease (GERD) in 9% and no diagnosis in 8%. Cough was due to one condition in 82%. Our treatment success rate was 92%. The most frequent causes of chronic cough (asthma, COPD, CUACS and GERD) could be determined in a general respiratory clinic with a sequential approach. The frequencies are different from those in a tertiary cough clinic, but outcome of specific therapy is successful in our patients.

Adolescent↗
PubMed2005

Noscapine suppresses angiotensin converting enzyme inhibitors-induced cough.

BACKGROUND: Dry cough is a common side-effect of the angiotensin converting enzyme inhibitors (ACEI) and is a major limiting factor of their use. It has been suggested that ACEI cause this side-effect by potentiation of the bradykinin effect. Previous work in our laboratory has shown that noscapine, an antitussive drug, inhibits the effect of bradykinin. METHODS: To investigate the effect of noscapine on ACEI-induced cough, 611 hypertensive patients who were being treated with ACEI were evaluated for the incidence of persistent dry cough. RESULTS: A cough had developed in 65 (10.6%) patients, two (3.1%) of whom also had severe respiratory distress that required hospitalisation and immediate discontinuation of the ACEI. Forty-two (64.6%) patients had developed a mild cough and 21 (32.3%) patients had developed a moderate to severe cough. The patients with moderate to severe cough received 15 mg of noscapine, orally three times daily, while they continued ACEI. Noscapine effectively resolved the cough in 19 (90%) patients within 4-9 days of starting treatment. CONCLUSION: Noscapine, possibly by inhibition of bradykinin synthesis, eliminates ACEI-induced cough in the majority of patients and allows them to continue with ACEI therapy.

Adult↗
PubMed1994

Peripheral and central sites of action of GABA-B agonists to inhibit the cough reflex in the cat and guinea pig.

1. The GABA-B receptor agonists baclofen and 3-aminopropylphosphinic acid (3-APPi) have antitussive activity in the cat and guinea pig. The purpose of this study was to investigate the sites of action of these GABA-B receptor agonists to inhibit the cough reflex. 2. Single intracerebroventricular (i.c.v.) cannulas were placed in the lateral ventricles of anaesthetized guinea pigs. Approximately 1 week later, the animals were exposed to aerosols of capsaicin (0.3 mM) to elicit coughing. Coughs were detected with a microphone and counted. 3. Cough was produced in anaesthetized cats by mechanical stimulation of the intrathoracic trachea and was recorded from electromyograms of respiratory muscle activity. Cannulas were placed for intravenous (i.v.) or, in separate groups of animals, intravertebral arterial (i.a.) administration of baclofen, 3-APPi, the centrally active antitussive drug codeine or the peripherally active antitussive drug BW443c. Dose-response relationships for i.v. and i.a. administration of each drug were generated to determine a ratio of i.v. ED50 to i.a. ED50, known as the effective dose ratio (EDR). The EDR will be 20 or greater for a centrally acting drug. 4. In the guinea pig, baclofen (3 mg kg-1, s.c.) and 3-APPi (10 mg kg-1, s.c.) inhibited capsaicin-induced cough by 50% and 35% respectively. The antitussive activity of baclofen was completely blocked by i.c.v. administration of the GABA-B receptor antagonist CGP 35348 (10 micrograms). Conversely, the antitussive effect of 3-APPi was unaffected by i.c.v. CGP 35348. However, systemic administration of CGP 35348 (30 mg kg-1, s.c.) completely blocked the antitussive activity of 3-APPi (10 mg kg-1, s.c.). In separate experiments baclofen alone (1 microg, i.c.v.) inhibited capsaicin-induced cough by 78%. 3-APPi (10 and 100 microg, i.c.v.) had no effect on capsaicin-induced cough in the guinea pig.5. In the cat, potencies (ED50) of the standards and GABA-B agonists by the i.v. route were: codeine(0.34 mg kg-1), BW443C (0.17 mg kg-1), baclofen (0.63 mg kg-1) and 3-APPi (2.3 mg kg-1). Potencies of these drugs by the i.a. route were: codeine, 0.013 mg kg-1; BW443C, 0.06mg kg-1; baclofen,0.016mg kg-1; and 3-APPi, 0.87 mg kg-1. The EDRs for each drug were: codeine, 26; BW443C, 3;baclofen, 39; and 3-APPi, 3.6 We conclude that in both the cat and guinea pig baclofen inhibits cough by a central site of action,while 3-APPi inhibits cough by a peripheral site of action.

Animals↗
PubMed2004

Identification of the tracheal and laryngeal afferent neurones mediating cough in anaesthetized guinea-pigs.

We have identified the tracheal and laryngeal afferent nerves regulating cough in anaesthetized guinea-pigs. Cough was evoked by electrical or mechanical stimulation of the tracheal or laryngeal mucosa, or by citric acid applied topically to the trachea or larynx. By contrast, neither capsaicin nor bradykinin challenges to the trachea or larynx evoked cough. Bradykinin and histamine administered intravenously also failed to evoke cough. Electrophysiological studies revealed that the majority of capsaicin-sensitive afferent neurones (both Adelta- and C-fibres) innervating the rostral trachea and larynx have their cell bodies in the jugular ganglia and project to the airways via the superior laryngeal nerves. Capsaicin-insensitive afferent neurones with cell bodies in the nodose ganglia projected to the rostral trachea and larynx via the recurrent laryngeal nerves. Severing the recurrent nerves abolished coughing evoked from the trachea and larynx whereas severing the superior laryngeal nerves was without effect on coughing. The data indicate that the tracheal and laryngeal afferent neurones regulating cough are polymodal Adelta-fibres that arise from the nodose ganglia. These afferent neurones are activated by punctate mechanical stimulation and acid but are unresponsive to capsaicin, bradykinin, smooth muscle contraction, longitudinal or transverse stretching of the airways, or distension. Comparing these physiological properties with those of intrapulmonary mechanoreceptors indicates that the afferent neurones mediating cough are quite distinct from the well-defined rapidly and slowly adapting stretch receptors innervating the airways and lungs. We propose that these airway afferent neurones represent a distinct subtype and that their primary function is regulation of the cough reflex.

Anesthesia↗
PubMed1987

Nocturnal cough in asthma.

The timing of nocturnal cough and its association with change in ambient temperature was documented in 11 asthmatic children, median age 5.1 years, while they were receiving continuous prophylaxis. Studies were performed in their homes on three nights. A voice activated system with electronic time signal recorded coughing. Ambient temperature was recorded every five minutes throughout the night on a Grant Squirrel data logger. Ten children coughed on 27 nights with a median of six bouts of coughing a night (range 0-272). The cough rate in the two hours after going to bed was significantly higher than the cough rate in the middle of the night (2-4 am or 4-6 am). Peak coughing times were 7-9 pm and 6-8 am. The room temperature was lowest between 5 and 7 am. There were no significant differences between cough rates during periods of rapid temperature change (more than 1 degree C an hour). The timing of nocturnal cough observed in this study differed from the known basophase of circadian cycles described for adults and children.

Asthma↗
PubMed1989

Chronic cough in a hospital population; its relationship to atopy and defects in host defence.

The background and aetiology of chronic cough were investigated by comparing 60 children under 6 years with simple cough, 60 children with asthma, and 60 controls. Both cough and asthma were more common in boys and associated with a history of eczema, chest deformity, and skin reactivity to inhaled allergens, but these findings were more prevalent in asthma than cough. House dust mite sensitivity was found in 34 (57%) children with cough, 45 (75%) with asthma, and six (10%) controls. Tests of immunological function showed some high concentrations of IgM in groups with both cough and asthma, but high IgE concentrations, eosinophilia, and lymphocytosis were significant only in asthma. IgG1 and IgG2 concentrations were raised in some children with cough or asthma, but the only low subclass concentrations were of IgG3 observed in the group with cough. Children with simple cough represented a heterogeneous population but many showed evidence of atopy. Major defects of immunity were not observed.

Asthma↗