Biomedical subjects
Publications and source records attributed to M R Hetzel.
Bronchial carcinoma causes some 30,000 deaths per year in the UK and only 10-20% of patients have any chance of surgical care. Radiotherapy and chemotherapy are mainly palliative treatments, yet they have considerable toxicity. In recent years laser bronchoscopy, with its advantages of speed, safety and freedom from toxicity, has proved a valuable addition to the established palliative therapy.
To obtain more accurate information about respiratory function in the elderly, we carried out spirometry and constructed maximum expiratory flow-volume curves in 136 volunteers over the age of 60 years (90 women, 46 men). Significant age related differences were found. Although vital capacity appeared well preserved in all groups, mid expiratory flow rates were low, even in lifelong non-smokers. On the basis of previous work, many of the subjects in this study would have been assessed as having small airways obstruction. The number of subjects is larger than in previous studies of airflow in this age group. Old people have often smoked, and many have a history of cardiovascular disease. Such individuals were included provided that they were fit and active for their age, and had no overt respiratory disease. It is argued that our findings will be of more clinical relevance to the elderly population than values derived either from population studies or studies that have used rigorous selection criteria to exclude subjects who smoked or had a history of non-respiratory disease.
Twenty one patients with tracheal tumours (10 primary and 11 secondary) have been treated with the neodymium YAG laser under general anaesthesia. Fourteen of these patients presented with impending asphyxia and in 11 cases this was dramatically relieved with emergency laser treatment. The improvements in peak expiratory flow (PEF) ranged from 26% to 512%. The three patients who did not respond were immediately given other treatments but died in hospital. The remaining seven patients were not in severe respiratory distress and were treated electively; all were thought to have benefited from their treatment, the mean increase in PEF being 36%. The improvement obtained in the 11 patients who responded to emergency laser treatment provided time in which to assess the disease carefully and plan the most appropriate longer term management with surgery, radiotherapy, tracheal stenting, or repeat laser treatment. The patients who were treated electively have either not required further treatment of have been managed with repeat laser treatments alone. Laser treatment provides an excellent method of resuscitating patients with life threatening tracheal obstruction and enables subsequent management to be carefully planned. In some cases this longer term management should be with further laser treatment alone.
Ninety seven patients with tracheobronchial tumours have been treated with the neodymium yttrium-aluminium-garnet (Nd YAG) laser over a period of 33 months. Fifty one of these patients were treated under local anaesthesia and 46 under general anaesthesia. The results obtained with the two methods have been compared retrospectively. The numbers of patients responding to treatment, the magnitude of the response, and the duration of palliation were similar in the two groups; significantly more treatment sessions, however, were required during each course of treatment under local anaesthesia. This advantage of general anaesthesia was thought to arise from the ability to continue treatment for longer and with greater efficiency. The use of the rigid bronchoscope with jet ventilation under general anaesthesia was also thought to provide better control of the airway and to allow more efficient clearance of blood and mucus. Two operative deaths occurred under local anaesthesia, when bleeding led to asphyxiation, but none have occurred under general anaesthesia. Treatment under general anaesthesia is not, however, without risk and is potentially hazardous in patients with severe chronic hypoxic lung disease.
Three consecutive doses of approximately 10 mg/kg of a once daily slow-release theophylline preparation (Uniphyllin) were given at 22.00 hours to 15 patients with nocturnal asthma who were recovering from an acute exacerbation of their asthma. Twenty-four hour plasma theophylline profiles were obtained after the first and third doses. Following the first dose, the mean peak level was 12.5 mg/litre, mean time to peak was 8.1 hours and mean apparent elimination half-life was 6.6 hours. Pharmacokinetic data were similar following the third dose. In nocturnal asthma, Uniphyllin should be given at about 20.00 hours to coincide peak levels with the time of maximum airflow obstruction.
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One hundred patients with tracheobronchial tumours were treated with the neodymium YAG (yttrium-aluminium-garnet) or argon laser for symptoms of airways obstruction caused by tumour (59 cases), complete collapse of a lung (17 cases), or recurrent haemoptysis (24 cases). Seventy four of them had relapsed or failed to respond to radiotherapy or chemotherapy and all were inoperable. Objective improvement in results of lung function tests or haemoptysis diary charts was seen in 37 patients with airways obstruction (63%), five (29%) with collapsed lung, and 14 (58%) with haemoptysis. Overall, 68 patients had symptomatic benefit and there was objective improvement in 56. Two deaths occurred in 288 treatment sessions both occurring as a result of asphyxia from minor haemorrhage in patients with advanced cylindromas and critical narrowing of the trachea or single remaining bronchus. In suitable patients with intraluminal tumour laser phototherapy is a valuable addition to conventional treatment.
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Laser treatment in carcinoma of the bronchus is essentially palliative and is suitable for only a few patients. Patients selected for laser treatment must have predominantly endobronchial growth with normal bronchial anatomy still identifiable and symptoms due to the obstruction or to haemoptysis. A total of 34 patients with carcinoma of the bronchus were treated with argon gas or neodynium yttrium aluminium garnet crystal lasers. Good palliation was obtained in just over half the cases of partial obstruction of the trachea or main bronchus, but best results were obtained in lesions of the trachea or main carina. Re-expansion of the collapsed lung was achieved in some cases but with considerable risk of pneumonia. Haemoptysis was controlled at least partly in several cases. Laser treatment has the advantage of having no toxicity or dose limit and may be used in cases of poor respiratory function. The procedure was better tolerated than radiotherapy or chemotherapy and its relatively lower cost may justify setting up laser units in major cities.
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The effect of inhaled or oral terbutaline on the subsequent response to inhaled terbutaline was studied using a double-blind cross-over technique in 12 asthmatic patients. 12 indices of respiratory function were obtained from the maximal flow-volume loop and a single-breath inert gas technique. These were used to evaluate the effect and to attempt to distinguish the site of action of the drug. Although the initial dose of inhaled terbutaline had a greater immediate effect than its oral counterpart there were no significant differences in the response to subsequently inhaled terbutaline. These findings do not support recent suggestions that oral administration has a greater effect on distal airways or promotes the effects of inhaled bronchodilators.