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Biomedical subjects

D M Geddes

Publications and source records attributed to D M Geddes.

At least 181 records · Page 10Linked to original sources
PubMed1985

Newly diagnosed cystic fibrosis in middle and later life.

Four patients with cystic fibrosis diagnosed in middle and later life are presented. All had chronic bronchopulmonary infection with a high sweat sodium concentration, and chest radiographic evidence of upper zone bronchiectasis. Two patients had pancreatic dysfunction. Sputum culture grew mucoid Pseudomonas aeruginosa in three patients and Haemophilus influenzae in one. Ages at diagnosis were 63, 42, 40, and 35 years. These patients confirm the possibility of occasional longevity in cystic fibrosis and emphasise the need to consider the diagnosis at all ages. They also provide encouragement for younger patients.

Adult↗
PubMed1985

Effect of oral high frequency ventilation by jet or oscillator on minute ventilation in normal subjects.

Normal subjects were asked to breathe through an open ended tube while high frequency oscillations were superimposed on tidal breathing via a side arm, either an eight inch (20 cm) loudspeaker or a jet ventilator being used. Both systems were comfortable and well tolerated. Spontaneous minute ventilation fell by 19-46% at frequencies up to 33 Hz without a rise in transcutaneous PCO2. Maximum ventilatory savings occurred at 1.6 Hz with the jet ventilator (p less than 0.01) and at a frequency corresponding to respiratory system resonance with the loudspeaker. This suggests that during oral high frequency ventilation pulmonary gas exchange is improved and leads to more efficient carbon dioxide excretion for a given minute ventilation. This technique provides a practical and simple method of supplementing breathing in conscious subjects, and it may also have application in the management of patients with acute or chronic respiratory failure, where intubation and conventional ventilation might be avoided.

Adult↗
PubMed1985

An oxygen conserving nasal cannula.

Oxygen administration via a nasal cannula incorporating a small collapsible reservoir (Oxymizer, Chad Therapeutics Inc, California) was compared with delivery via a standard nasal cannula. Twelve patients with chronic, stable hypoxaemia (arterial oxygen tension less than 60 mm Hg (8.0 kPa)) were studied. Transcutaneous oxygen and carbon dioxide tensions were recorded by skin electrodes and oxygen saturation by ear oximetry. Baseline measurements during the breathing of air were compared with those made during the breathing of oxygen at flow rates of 0.5, 1.0, and 2.0 l/min via each device. Increases in saturation and transcutaneous oxygen tension were significantly greater at each flow rate with the reservoir device than with the conventional cannula. To produce similar improvements in oxygenation the reservoir device required an oxygen flow rate about half that of the conventional cannula. Use of the reservoir device may reduce the inconvenience and perhaps the cost of supplying domiciliary oxygen, and prolong the time during which patients may rely on a portable cylinder.

Evaluation Studies as Topic↗
PubMed1985

Increase in mucociliary clearance in normal man induced by oral high frequency oscillation.

Data on the effect on mucociliary clearance of oral high frequency oscillation is conflicting. By means of a technique to superimpose high frequency oscillation on tidal breathing, changes in mucociliary clearance during high frequency oscillation were studied in seven normal non-smokers by monitoring the clearance of inhaled radiolabelled aerosol from the lungs. After inhalation of 5 microns technetium 99m labelled particles under controlled conditions, whole lung clearance was monitored by scintillation counters half hourly for six hours with a final count at 24 hours, from which tracheobronchial deposition and clearance could be calculated. Control and high frequency oscillation studies were performed on separate days in random order. Oral high frequency oscillation was applied by a bass loudspeaker through a mouthpiece to superimpose sinewave oscillations (RMS input pressure 1.2 cm H2O, mean pressure zero) on normal breaths. On high frequency oscillation days 30 minutes of oscillation alternated with 30 min of rest. Between 3 and 4.5 hours mucociliary clearance with high frequency oscillation exceeded control by about 10% (p less than 0.05). The mean time taken to eliminate 90% of deposited radioaerosol from the tracheobronchial tree fell from 4 hours 50 minutes (range 1 h 52 min-6 h 50 min) during control to 3 hours 43 minutes (range 2 hr 28 min-5 hr 54 min) during the high frequency oscillation run (p less than 0.05). Possibly this comfortable, simple technique would be of therapeutic benefit to patients with chronic sputum retention and merits further investigation.

Adult↗
PubMed1985

Transepithelial potential difference in cystic fibrosis.

In cystic fibrosis the potential difference between interstitial fluid and the surface of respiratory and sweat duct epithelia is abnormally large. This study attempted to confirm this finding and investigate its value for a diagnostic test. With a subcutaneous reference electrode the mean potential difference of the inferior turbinate was -25 mv in 19 patients with cystic fibrosis, which was significantly greater than the difference of -13 mv in 22 normal subjects (p less than 0.02). Of the observations in the patients with cystic fibrosis, 67% were greater than the largest potential difference observed in normal individuals. Potential differences from the lip and forearm were also significantly greater in cystic fibrosis than in normal subjects, but there was considerable overlap. Changes in the electrical properties of nasal epithelium and skin have been confirmed in cystic fibrosis, but these have limited use for diagnosis.

Adult↗
PubMed1985

Prognostic significance of laboratory parameters measured at diagnosis in small cell carcinoma of the lung.

An analysis of prognostic factors in small cell lung cancer has been carried out using data from 371 patients treated with identical chemotherapy in the context of a large prospectively randomized clinical trial. Prognosis was shown to be strongly correlated with initial performance status, disease extent, and routine biochemical tests at the time of diagnosis. Plasma albumin, plasma sodium, alkaline phosphatase, and gamma-glutamyl transpeptidase were all predictive of survival. An initial hemoglobin of less than 11 g/dl was also predictive, but age, sex, and initial WBC count were not. A multiple regression analysis identified performance status, plasma alkaline phosphatase, plasma sodium, disease extent, and plasma albumin as contributing independently to survival. Using these parameters, three prognostic groupings could be defined. The combination of performance status and the biochemical values more closely predicted survival than categorization on the basis of disease extent defined by clinical, radiological, and scanning criteria. Response to chemotherapy was strongly correlated with these prognostic groupings. A much higher response rate occurred in patients in the best prognostic category in whom the tumor mass is assumed to be smaller. These results provide a simple basis for predicting prognosis in small cell lung cancer and indicate that the better prognosis in chemotherapy responders is not solely due to the treatment.

Alkaline Phosphatase↗
PubMed1985

High frequency ventilation.

What is high frequency ventilation? Is it useful or just another transatlantic fad? Apart from appearing to break all the rules of physiology, this technique has definite advantages over conventional ventilation in certain areas and great potential in others.

Humans↗
PubMed1984

High frequency oscillations improve nasal mucociliary transport.

The saccharin clearance time technique was used to determine the effect upon nasal mucociliary transport of sine wave oscillations. Nasal air was oscillated at 8 Hz, 14 Hz, and 20 Hz by a loudspeaker attached to a nasal mask. Mucociliary transport was significantly increased at all frequencies with an overall mean rise of 161%. Because sine waves have zero mean pressure and flow, the improvement is more likely to be caused by changes in mucus viscoelasticity or ciliary function rather than by a direct physical effect on mucus velocity. This simple and comfortable technique may have practical application in patients with overproduction or retention of mucus within the nasal passages or intrathoracic airways.

Adult↗
PubMed1984

Self-administered home intravenous antibiotic therapy in bronchiectasis and adult cystic fibrosis.

10 patients (mean age 23.1, range 17.1-40.5 years), 8 with cystic fibrosis (CF), and 2 with advanced bronchiectasis without CF, were taught, while being treated in hospital for exacerbations of pseudomonas infection, how to continue to give themselves intravenous antibiotics at home. They were discharged after satisfactory antibiotic levels had been achieved, and 22 courses were given at home over a total of 116 patient-days. In 14 of these, the greater part of the course was given at home (mean duration 6.6, range 5-10 days); 2 of these were given without admission to hospital. In the 8 patients with two or more infective exacerbations within a 12-month period there was no difference between home and hospital treatments in clinical improvement or in relapse time, defined as the interval between completion of treatment and subsequent antibiotic therapy. Self-administration of antibiotics intravenously at home for selected adults with cystic fibrosis and severe bronchiectasis reduces hospital stay and does not seem to be associated with an increased rate of recurrent infection.

Adolescent↗
PubMed1984

Radiotherapy in small cell cancer of the lung treated with combination chemotherapy: a controlled trial.

Three hundred and seventy one patients with extensive or limited small cell cancer of the lung took part in a randomised trial to evaluate irradiation of the primary tumour in patients treated with combination chemotherapy. They were randomly allocated to treatment either with chemotherapy alone (198) or with both chemotherapy and radiotherapy (173). All 371 initially received 12 weeks of chemotherapy after which they were categorised according to response. Only those with stable or responding disease continued with their allotted treatment. Thus 144 received chemotherapy alone and 135 received both chemotherapy and radiotherapy. The design of the study permitted analysis of the effect of radiotherapy according to initial extent of disease and quality of early response to chemotherapy. Radiotherapy (40 Gy (4000 rad), one fraction a day over 20 days) did not improve the survival of patients in any category of initial extent of disease or early response to chemotherapy and was not effective in preventing local relapse.

Carcinoma, Small Cell↗
PubMed1984

Bronchoalveolar lavage in the diagnosis of diffuse pulmonary shadowing.

Bronchoalveolar lavage (BAL) was performed during fibreoptic bronchoscopy in 79 patients with undiagnosed diffuse radiographic pulmonary shadowing and in 20 control subjects undergoing investigation for respiratory symptoms not associated with diffuse radiographic shadowing. The highest percentages of cells other than macrophages found in BAL fluid from the controls were 11% for lymphocytes and a total of 10% for neutrophils and eosinophils. 72 (91%) of the patients with diffuse shadowing had higher percentages of one or more of these inflammatory cell types than were found in any of the controls. Patients with increased lymphocytes differed in their eventual diagnosis from those without increase lymphocytes but with increases in other inflammatory cells (P less than 0.001). The use of BAL cell profiles as an aid to diagnosis in certain situations is illustrated by calculation of predictive values using Bayes' theorem. BAL has diagnostic value in the investigation of diffuse pulmonary shadowing if the cell profile is considered in conjunction with other information.

Adolescent↗
PubMed1983

Theophylline prescribing, serum concentrations, and toxicity.

Slow-release theophylline preparations have been prescribed increasingly at the Brompton Hospital, and a serum theophylline assay is requested about once for every ten prescriptions. In a period of eighteen months 1913 such assays were performed, and their influence on management was assessed by retrospective analysis in two groups--113 outpatients on stable dosage with no recent exacerbations of disease; and 28 inpatients and outpatients with concentrations exceeding 25 mg/l. In those with stable treatment, there was only a loose relation between dose and serum theophylline level. High serum levels were associated with abnormal liver function, diuretic use, and duplicate prescribing. When serum theophylline levels were reported high, dosage was always reduced, whereas a low serum theophylline prompted dosage increase in only one-third of patients. Of the patients with very high serum theophylline concentrations (over 25 mg/l), 18 had been receiving oral theophylline and 10 aminophylline by infusion. 3 had seizures, of whom 2 died, and 1 patient was resuscitated after cardiac arrest. Unsuspected theophylline toxicity may be responsible for considerable hidden morbidity.

Administration, Oral↗
PubMed1983

Dihydrocodeine for breathlessness in "pink puffers".

Eighteen patients with severe breathlessness due to chronic airflow obstruction completed a randomised placebo controlled double blind cross over trial of the effect of dihydrocodeine 15 mg on breathlessness, disability, and exercise tolerance. There were three periods of one week each. During the first two weeks patients were instructed to take dihydrocodeine 15 mg or placebo 30 minutes before exercise as required up to three times daily. During the third week patients received either dihydrocodeine or placebo on alternate days. During the weekly dihydrocodeine period patients were more mobile (pedometer distance increased by 16.8%) and less breathless (daily visual analogue score of breathlessness reduced by 17.8%). This benefit was confirmed by treadmill testing at the end of each treatment period, when maximum distance walked was 16.5% higher and breathlessness 11.8% less after dihydrocodeine compared with placebo. Similar benefit in breathlessness occurred during alternate day treatment. No adverse effects were encountered. Dihydrocodeine 15 mg 30 minutes before exercise offers appreciable benefit to patients with severe breathlessness due to chronic airflow obstruction.

Aged↗
PubMed1983

Are "pink puffers" more breathless than "blue bloaters"?

Breathlessness, disability, and exercise tolerance were assessed in 26 patients with severe chronic airflow limitation (forced expiratory volume in one second (FEV1) less than or equal to 1 litre) divided into two groups--15 patients who were normocapnic (pressure of arterial carbon dioxide (Paco2) less than 5.5 kPa (less than 41.4 mm Hg)), and 11 patients who were hypercapnic (Paco2 greater than 6 kPa (greater than than 45.1 mm Hg)). The two groups were well matched for spirometric values (FEV1 0.59 1 and 0.62 1, respectively). All of the hypercapnic patients could improve blood gas tensions towards normal by hyperventilation. There were no significant differences in visual analogue scores of breathlessness during treadmill exercise, disability (oxygen-cost diagram, dyspnoea grade), or exercise tolerance (six-minute walk, maximal consumption of oxygen during bicycle ergometry, distance walked to exhaustion in progressive treadmill test). The findings show that the "fight" to maintain normal blood gas tensions in the face of severe airflow limitation does not have an appreciable cost in terms of disability.

Carbon Dioxide↗