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Biomedical subjects

P Lockwood

Publications and source records attributed to P Lockwood.

6 recordsLinked to original sources
PubMed1991

Lung function and radiation response.

This study investigated whether impaired respiratory function affected the response to radiotherapy. A prospective study was performed in which lung function, arterial oxygen and haemoglobin concentration were examined, before treatment with radical radiotherapy, in 141 patients with advanced non-small cell lung cancer and head and neck cancer. The findings were considered to reflect the physiological conditions present at the time of radiotherapy and these were related to acute normal tissue reactions and tumour control. Although 53% of the patients showed some impairment of lung function and 47% demonstrated a haemoglobin oxygen saturation below the normal range, oxygen partial pressure was below expected levels in fewer patients (27%) and total arterial oxygen content was below normal in only 12% of patients. No correlation was found between the tests performed and the severity of acute morbidity or with local tumour control. In the patients with carcinoma of the bronchus, there was a trend for incomplete tumour control to be associated with a lower haemoglobin level, but this did not reach statistical significance. In patients selected for curative radiotherapy, lung function would not appear to be an important factor influencing the response of normal tissues or tumour to irradiation.

Adult↗
PubMed1990

Thermal debracketing of orthodontic resins.

Ten commercial brands of orthodontic bonding materials representing three modes of delivery systems (two-paste, no-mix, and powder/liquid) were used to bond stainless steel brackets to bovine teeth. Heat was applied to the bracket, and the temperature at debonding was noted for each type of resin. The two-paste systems required a higher temperature to debond than did the no-mix systems. The powder/liquid system required the lowest temperature. There is a direct relationship between filler content and debonding temperature. There is an inverse exponential relationship between debonding temperature and load needed to cause debracketing. Room-temperature debonding showed failure at the bracket/resin interface with evidence of cohesive enamel fracture. Thermal debonding showed no evidence of overt enamel fracture, and failure site shifted toward the tooth/resin interface. Ceramic brackets required almost twice the time to debracket than did stainless steel brackets.

Animals↗
PubMed1990

Bronchoscopic cryotherapy for advanced bronchial carcinoma.

A prospective study was carried out to assess the value of bronchoscopic cryotherapy for palliation of inoperable bronchial carcinoma with bronchial obstruction. Symptoms, lung function, and chest radiographic and bronchoscopic findings were recorded serially before and after 81 cryotherapy sessions in 33 consecutive patients. Most patients improved in terms of overall symptoms, stridor, and haemoptysis and they had an overall improvement in dyspnoea. Objective improvement in lung function was seen in 58% of patients and the changes in lung function correlated with symptoms. Bronchoscopic evidence of relief of bronchial obstruction was seen in 77% of patients and 24% showed improvement in degree of collapse on the radiograph. There were no important complications. These results compare favourably with the results in published series of patients having laser therapy. It is concluded that bronchoscopic cryotherapy is valuable for the palliation of inoperable bronchial carcinoma.

Aged↗
PubMed1978

Airway obstruction in patients with carcinoma of the bronchus.

Two types of airway obstruction can be displayed by patients with carcinoma of the bronchus: localised obstruction due to the tumour alone and generalised obstruction due to the tumour plus bronchitis. The presence of bronchitis is known to increase the risk of cardiopulmonary complications after lung resection. The patients studied who had function-related post-operative complications differed from those without complications in the levels of the maximal mid-expiratory flow rate determined before operation. This difference is suggested as displaying the presence of significant degrees of bronchitis. A possible explanation for the maximal mid-expiratory flow rate findings in the two types of airway obstruction is put forward and the use of this measurement is recommended in the pre-operative assessment of patients with carcinoma of the bronchus prior to thoracotomy. Values below 1.2 litres/sec are considered to imply increased risks of the complications, whilst values above 1.8 litres/sec are thought to indicate decreased risks.

Aged↗
PubMed1975

Treatment of trigeminal neuralgia in the aged by a simplified surgical approach (percutaneous electrocoagulation).

Trigeminal neuralgia can be excruciatingly painful. For aged patients, among whom trigeminal neuralgia most commonly occurs, medical therapy may often afford relief of pain. However, since this disorder is likely to become worse with increasing age, medical therapy eventually may fail because of increasing drug requirements and intolerable side effects. Major forms of surgical treatment requiring craniotomy may afford longstanding relief but are associated with significant side effects in 3-5 per cent of cases. For these reasons the authors began to test a new surgical approach, i.e., stereotaxic percutaneous electrocoagulation of the trigeminal nerve. More than 300 patients have been treated by this technique in the past five years. Successive radiofrequency lesions allow the production of a graded sensory deficit sufficient to relieve pain while preserving touch and motor function in the face. Unnecessary suffering from the severe pain of trigeminal neuralgia need not occur because of age or a debilitated condition which might ordinarily preclude surgical treatment. More than 100 patients over 65 years of age (4 of them older than 90) have been treated. Of this group, 93 per cent reported good to excellent results. Seven per cent have had some recurrent pain during the follow-up period; however, recoagulation has been required in only 5 per cent of these patients. Recoagulation may be readily performed in any patient who shows evidence of fading of the sensory deficit. The electrocoagulation technique and the results in elderly patients are discussed.

Aged↗