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Biomedical subjects

T Higenbottam

Publications and source records attributed to T Higenbottam.

At least 145 records · Page 8Linked to original sources
PubMed1982

Responses to cigarettes of various tar contents.

Specific conductance was measured before and within ten minutes of smoking a cigarette in 36 smokers on 210 occasions. Five types of cigarette were used including the equivalent of a 1956 unfiltered cigarette. Cigarettes were smoked in the smokers' usual fashion. Significant decreases in specific conductance occurred on only 19 occasions in 13 subjects and were most frequent with the cigarette with the highest tar content currently available. Examining the overall results the only significant change was an increase in specific conductance in the control, non-smoking period. We conclude that irritant qualities of tobacco smoke increase with tar content but airway narrowing lasting up to ten minutes is an uncommon event when cigarettes are smoked normally. Most smokers adapt to or avoid any sustained acute airway response to tobacco smoke whatever its tar content.

Airway Resistance↗
PubMed1981

Influence of breath holding at total lung capacity on maximal expiratory flow measurements.

1. Forced exhalations performed from volumes below total lung capacity, so-called partial expiratory flow-volume curves, are suggested to be more sensitive in detecting airways bronchoconstriction than maximal expiratory flow-volume curves begun at total lung capacity. 2. In eight healthy men both maximal and partial expiratory flow-volume curves were measured where breath was held at total lung capacity of 70% of vital capacity respectively, for either 0 or 15 s before performing the forced exhalation. An histamine aerosol was used to provoke bronchoconstriction. 3. The results showed that the 15 s breath hold caused greater reduction in expiratory flow rates after histamine for both maximal and partial expiratory flow-volume curves than either manoeuvres performed with no breath hold. 4. A breath hold of 15 s at total lung capacity appeared to make the maximal expiratory flow-volume curve as sensitive as a partial expiratory flow-volume curve in detecting the response to histamine as well as providing measurements of forced expiratory volume in 1 s and vital capacity. Forced spirometry after a 15 s breath hold at total lung capacity therefore provides an easy and sensitive technique for detecting bronchoconstriction.

Airway Obstruction↗
PubMed1981

Respiratory activity of the vocal cords in normal subjects and patients with airflow obstruction: an electromyographic study.

1. A surface electrode was used to record electromyographic activity of the posterior cricoarytenoid muscle during breathing in normal subjects and patients with airflow obstruction. 2. Phasic activity of the posterior cricoarytenoid muscle was demonstrated. This was present on inspiration and absent on expiration. 3. Phasic inspiratory activity in normal subjects was present only during periods of voluntary hyperventilation, increasing with tidal volume, whereas in patients with airflow obstruction inspiratory activity was present even during resting breathing and failed to increase further during voluntary hyperventilation. 4. The posterior crico-arytenoid muscle may be considered as an inspiratory muscle acting analogously to other accessory respiratory muscles.

Adult↗
PubMed1980

Lung function and symptoms of cigarette smokers related to tar yield and number of cigarettes smoked.

In a survey of over 18 000 male civil-servants, tar yield and number of cigarettes smoked daily were related to lung function and respiratory symptoms. Both phlegm production and airflow obstruction among smokers increased with daily cigarette consumption. Tar yield influenced phlegm production but not the degree of airflow obstruction. However, those smoking more than twenty cigarettes per day lost most of the advantage of smoking low-tar cigarettes since their phlegm production was the same as that of high-tar cigarette smokers. Ex-smokers had better lung function than current smokers with comparable total cigarette consumption; the difference between ex-smokers and current smokers was not related to the length of time that ex-smokers had abstained from smoking. Despite a reduction in phlegm production a change to low-tar cigarettes, may only be associated with an improvement in lung function if dialy cigarette consumption is also reduced. After stopping smoking there may be an initial improvement in lung function but ex-smokers never fully restore their lung function, no matter how long they have abstained from smoking. Although lower tar yield may reduce phlegm production and the risk of cancer, the development of airways obstruction may not be related to the tar content of cigarettes. Rather, the gaseous phase of tobacco smoke may contain the irritant agents leading to airways obstruction.

Adult↗
PubMed1980

Practical importance of a preceding full inhalation or exhalation upon the measurement of airway resistance.

1. Airway resistance was measured close to functional residual capacity before and after a full inhalation of total lung capacity, as well as before and after a full exhalation to residual volume. 2. The effects of these volume manoeuvres upon airway resistance (and associated lung volume) were determined in four resting normal male subjects and in six normal men during experimentally induced bronchoconstriction after breathing an air/histamine mist from a Wright's nebulizer. 3. In four men the duration of the effect of a full inhalation upon airway resistance after induced bronchoconstriction was assessed separately. 4. Neither a full inhalation nor a full exhalation altered airway resistance under normal conditions. However, a full inhalation reduced airway resistance in the presence of bronchoconstriction and this effect lasted for a period of 45 s. Even with bronchoconstriction, a full exhalation had no effect on airway resistance. 5. Account must therefore be taken of the potential reduction in airway resistance which may result from a full inhalation, particularly when indirect measurements of airway function which involve a full inhalation, such as forced spirometry, are used to assess airway obstruction.

Airway Resistance↗
PubMed1980

Cigarette smoke inhalation and the acute airway response.

The acute airway response to smoking varying numbers (one to four) of identical cigarettes in rapid succession and smoking single cigarettes of differing tar/nicotine yields was assessed repeatedly in 13 healthy smokers. The airway response was variable, indicating airway narrowing consistently in only three subjects. There appeared no difference between forced spirometry and measurement of airway resistance in detecting the airway response. No relationship was observed between the airway response and amount of smoke inhaled into the lungs as measured either by changes in venous blood nicotine or percentage carboxyhaemoglobin. When five smokers inhaled smoke directly from a cigarette acute airway narrowing was consistently observed. A normal smoking pattern consisting of an initial drag of smoke into the mouth, followed after a pause by inhalation of smoke diluted with air, did not consistently cause airway narrowing although similar amounts of smoke as the direct drag were inhaled as assessed by changes in venous blood nicotine. The manner of smoke inhalation affects the relative concentrations of the different constituents of smoke reaching the lungs and also appears to be the main determinant of the acute airway response to smoking, which was unrelated to the number of cigarettes smoked or the tar content of the smoke. This suggests that patterns of smoke inhalation may influence the pathogenesis of bronchial disease associated with smoking.

Adult↗
PubMed1980

Bronchial disease in ulcerative colitis.

Ten patients with ulcerative colitis, all of whom were non-smokers, presented with a productive cough. In six, the chest radiography was normal and cough was the only symptom; three of these patients had a minor obstructive ventilatory defect on testing. Four patients complained of exertional dyspnoea and had both an abnormal chest radiograph with bilateral pulmonary shadows and a mixed obstructive and restrictive ventilatory defect. Bronchial epithelial biopsies from four patients (two with and two without pulmonary shadows) revealed basal reserve cell hyperplasia, basement membrane thickening, and submucosal inflammation, changes more usually associated with cigarette smoking. Inhaled beclomethasone diproprionate relieved cough in seven patients. The occurrence of airway epithelial disease in association with ulcerative colitis raises the possibility of a systemic mechanism affecting both bronchial and colonic epithelium. It does not seem likely that sulphasalazine was the cause of the pulmonary syndrome in these subjects.

Adult↗
PubMed1980

Narrowing of glottis opening in humans associated with experimentally induced bronchoconstriction.

An index of the separation of the vocal cords during tidal breathing was obtained in humans; the area of the glottis opening was assessed from photographs of the vocal cord taken on inspiration and expiration via a fiber-optic bronchoscope. The index of glottis width was calculated from the area by dividing it with, as reference, the anteroposterior diameter of the glottis, a relatively invariant measurement of the glottis during breathing. Both inspiratory and expiratory glottis width decreased after histamine had been inhaled (dose range 2.4-9.6 mg) or injected intravenously (dose of 4 micrograms/kg), being associated with a reduction in forced expired volume in 1.0 s. Histamine, which acts directly on smooth muscle or bronchial irritant receptors, is unlikely to have directly caused contraction of the striated laryngeal musculature or to have stimulated receptors above the vocal cords. The narrowing of the glottis opening observed in humans may represent a reflex narrowing of the glottis in association with a reduction of intrapulmonary airway caliber.

Adult↗
PubMed1980

Acute effects of smoking a single cigarette on the airway resistance and the maximal and partial forced expiratory flow volume curves.

The acute airway response to smoking a single cigarette was assessed in eight symptom-free male smokers. The changes in airway function were determined using a computer analysis of maximal and partial expiratory flow volume curves together with measurement of airway resistance. The amount of smoke inhaled was assessed by measuring levels of nicotine in venous blood. When the results of all studies were analysed for the group as a whole only small and inconsistent changes in airway function were observed after smoking a cigarette, although all the subjects appeared to inhale the smoke. Although the group showed inconsistent changes, one subject exhibited a change on all four occasions in the studies using the maximal and partial expiratory flow volume curves. This was seen particularly for Vmax50 and Vmax40 obtained from the maximal and partial expiratory flow volume curves respectively. There appeared to be no difference between the two manoeuvres in their sensitivity to smoke-induced change. One subject showed a response to smoking when airways resistance was measured but this was on only one of two occasions. It is therefore possible that certain smokers are more susceptible to inhaled cigarette smoke and such individuals may be those who develop chronic airflow obstruction. The absence of a group effect was attributed to any smoking response being smaller than the other factors which affect measurements of airway function.

Adult↗
PubMed1979

Further clinical observations on the pulmonary effects of paraquat ingestion.

Five patients are reported who developed evidence of acute lung damage after proved ingestion of paraquat. In two the lung changes resolved; in one an aspiration pneumonia occurred, which was successfully treated, while two developed fatal pulmonary oedema. These pulmonary complications after paraquat intoxication appear more common than the progressive pulmonary fibrosis previously described. It is suggested that acute pulmonary oedema is a response to large doses, usually of Gramoxone, that subclinical lung changes result from small doses, usually of Weedol, and that pulmonary fibrosis occurs after intermediate doses. Preliminary data on plasma paraquat concentrations suggest that these are of value in prognosis.

Adult↗
PubMed1978

Acute renal failure from the use of acetazolamide (Diamox).

The clinical histories of two patients are presented, who both developed haemorrhagic anuria after a short course of therapy with the carbonic anhydrase inhibitor, acetazolamide (Diamox). The clinical findings, in particular the radiological changes, are illustrated in this potentially fatal condition. The therapeutic success of immediate relief of the ureteric obstruction is emphasized and it is hoped that this report will act as a reminder of the importance of this agent as a cause of anuria.

Acetazolamide↗
PubMedDate not supplied

Methemoglobin levels in smokers and non-smokers.

The authors analyzed the blood of a group of 336 smokers and 336 non-smokers to determine if tobacco smoke, potentially the major source of nitrogen oxide pollution for 40% of the adult population, significantly reduces oxygen carrying capacity as a result of methemoglobin formation. Each blood sample was analyzed for carboxyhemoglobin, methemoglobin, and hemoglobin using an automated spectrophotometer. The mean value of methemoglobin in the smokers did not exceed that in the non-smokers; in fact, the level in the non-smokers was significantly greater. As expected, carboxyhemoglobin levels in smokers substantially exceeded those in non-smokers. The authors conclude that methemoglobin arising from cigarette smoke exposure does not interfere with the oxygen carrying capacity of the blood in smokers.

Carboxyhemoglobin↗
PubMedDate not supplied

Controlled-release theophylline in the treatment of nocturnal asthma.

A total of 104 asthmatic patients with symptoms of asthma and/or a 'morning dip' in the peak expiratory flow rate (PEFR) who were receiving multiple therapies, including inhaled or oral steroids, were treated in addition once nightly with controlled-release theophylline in an 8-week double-blind, placebo-controlled cross-over study. Theophylline produced an improvement in symptoms of cough, wheeze, sleep disturbance and PEFR in the 73 completing patients compared to run-in and placebo treatment. Theophylline also produced an improvement in the forced expiratory volume in 1 s and forced vital capacity relative to baseline, and in the difference between actual and predicted PEFR values. Nausea was the most frequent side-effect but both patients' and investigator's global impressions of the effect of study medication were in favour of theophylline.

Adolescent↗
PubMedDate not supplied

Prospective study of transbronchial biopsies in the management of heart-lung and single lung transplant patients.

A prospective study of 219 bronchoscopies in 54 heart-lung and in 2 single lung transplant recipients was undertaken over a 12-month period by a single operator. For histologic study, an average of 17.3 transbronchial biopsy specimens (range, 6 to 56) were taken from three lobes (or from two lobes and lingula of one lung). A further two specimens were taken for culture. The average procedure time was 14.4 minutes (SE 0.31). An estimate of the probability of rejection being missed, depending on the number of specimens taken and based on the method of Gilman and Wang, suggests 18 biopsy specimens are required to have 95% confidence of diagnosing rejection. Sensitivity for diagnosing rejection by histologic study of transbronchial biopsy specimens was 94%, and specificity was 90%. The simple grading of severity of rejection that was used was related both to the number of specimens demonstrating rejection and to the severity of graft airway mucosal inflammation seen at bronchoscopy. The major complication encountered, on 27 occasions, was bleeding of more than 100 ml. On no occasion did bleeding result in any long-term complication. Extensive transbronchial biopsy is a simple, relatively safe, and quick procedure, with a high sensitivity and specificity for diagnosing rejection and lung infection.

Adolescent↗