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Biomedical subjects

R D Stevenson

Publications and source records attributed to R D Stevenson.

At least 55 records · Page 3Linked to original sources
PubMed1992

Improving management of asthma: closing the loop or progressing along the audit spiral?

OBJECTIVE: To assess whether the management of asthma has improved from three consecutive surveys. DESIGN: Retrospective case note survey of acute asthma admissions in 1983 and 1989; case notes selected from 1985-6 survey of prospectively identified patients to include only patients with a final discharge code of asthma. SETTING: A large city teaching hospital. Patients--101 patients with acute asthma as the primary diagnosis in 1983; 85 in 1985-6; and 133 in 1989, 14 of whom were subsequently transferred elsewhere. MAIN MEASURES: Conformity with a checklist of important aspects of the process of asthma management including initial assessment, treatment, supervision, and discharge and review arrangements. RESULTS: All patient groups were similar in age, smoking habit, and stay in hospital and, as an objective guide to severity of asthma, had similar initial pulse rates. Major improvements occurred in management: by 1989, 119(90%) patients were treated with oral corticosteroids (69(68%), 67(79%) in 1983, 1985-6 respectively) and 109(82%) with oxygen (62(61%), 51(60%)) (both p < 0.001). 114(86%) had regular recording of peak flow measurements (53(52%), 54(64%); p < 0.001), and 103/119(86%) were discharged taking oral corticosteroids (66(65%), 63(74%); p < 0.01). Significantly fewer patients, however, had their regular inhaled corticosteroid treatment increased on discharge (38/119(32%) v 53(52%), 39(46%); p < 0.01), but more were receiving high dose inhaled treatment on admission. CONCLUSIONS: The management of asthma improved significantly, and the normal practice of doctors has changed in an area of practice with longstanding problems.

Asthma↗
PubMed1991

Subclinical pulmonary function defects following autologous and allogeneic bone marrow transplantation: relationship to total body irradiation and graft-versus-host disease.

Pulmonary function results pre- and post-transplant, to a maximum of 4 years, were analyzed in 98 patients with haematological disorders undergoing allogeneic (N = 53) or autologous bone marrow transplantation (N = 45) between 1982 and 1988. All received similar total body irradiation based regimens ranging from 9.5 Gy as a single fraction to 14.4 Gy fractionated. FEV1/FVC as a measure of airway obstruction showed little deterioration except in patients experiencing graft-versus-host disease in whom statistically significant obstructive ventilatory defects were evident by 6 months post-transplant (p less than 0.01). These defects appeared to be permanent. Restrictive ventilatory defects, as measured by reduction in TLC, and defects in diffusing capacity (DLCO and KCO) were also maximal at 6 months post-transplant (p less than 0.01). Both were related, at least in part, to the presence of GVHD (p less than 0.01) or use of single fraction TBI with absorbed lung dose of 8.0 Gy (p less than 0.05). Fractionated TBI resulted in less marked restricted ventilation and impaired gas exchange, which reverted to normal by 2 years, even when the lung dose was increased from 11.0 Gy to between 12.0 and 13.5 Gy. After exclusion of patients with GVHD (30% allografts) there was no significant difference in pulmonary function abnormalities between autograft and allograft recipients.

Adolescent↗
PubMed1991

The development of normal feeding and swallowing.

The development of feeding skills is an extremely complex process influenced by multiple anatomic, neurophysiologic, environmental, social, and cultural factors. Most children negotiate the necessary developmental sequence without significant difficulties. An understanding of the development of normal feeding abilities aids the pediatrician in monitoring this remarkable process in his or her normal patients. This understanding also helps equip the pediatrician who is challenged by a child with complex feeding problems. The following statements summarize the major elements of feeding development. 1. Structural integrity is essential to the development of normal feeding and swallowing skills. Infant anatomy differs from adult anatomy. Anatomic changes associated with growth affect feeding function. 2. Normal infant feeding is reflexive, under brainstem control, and does not require suprabulbar input. As feeding development progresses, basic brainstem-mediated responses come under voluntary control through the process of encephalization. 3. The mature swallow consists of a voluntary oral-preparatory phase, a voluntary oral phase, and involuntary pharyngeal and esophageal phases. The infant swallow does not have a voluntary oral-preparatory and oral phase but is otherwise similar. 4. The neurophysiologic control of feeding and swallowing is complex and involves sensory afferent nerve fibers, motor efferent fibers, paired brainstem swallowing centers, and suprabulbar neural input. Close integration of sensory and motor functions is essential to the development of normal feeding skills. 5. Feeding development, although dependent on structural integrity and neurologic maturation, is a learned progression of behaviors. This learning is heavily influenced by oral sensation, fine and gross motor development, and experiential opportunities. 6. The basic physiologic complexity of feeding is compounded by individual temperament, interpersonal relationships, environmental influences, and culture. 7. The main goal of feeding is the acquisition of sufficient nutrients for optimal growth and development. Malnutrition may result directly from feeding problems and may also help perpetuate them. 8. Protection of the airway during swallow is a reflexive, multileveled function consisting of the apposition of the epiglottis and aryepiglottic folds and the adduction of both false and true vocal folds.

Deglutition↗
PubMed1991

Alveolar macrophage chemotaxis in fire victims with smoke inhalation and burns injury.

In vitro migration of alveolar macrophages was studied in 24 fire victims and 19 controls; all subjects were cigarette smokers. Unstimulated (P = 0.01) and stimulated migration towards casein-(P = 0.01) and zymosan-activated serum (P = 0.002) of macrophages from smoke inhalation patients (SI) (n = 19) was increased when compared to control subjects (CS). Migration of alveolar macrophages from patients with burns without smoke inhalation (burns only, BO) was not increased. Patients with smoke inhalation and no burns (smoke only, SO) (n = 9) had increased migration when compared to controls but this was not statistically significant. Patients with smoke inhalation and burns (SB) (n = 10) had increased unstimulated migration (P = 0.01) and increased migration towards casein (P less than 0.005), ZAS (P less than 0.002) and F-met-leu-phe (P less than 0.05) when compared to controls (CS). Lavage fluid from the fire victims displayed chemotactic activity towards normal human neutrophils and its analysis for the components of the complement cascade proved positive (Clq, Clr, Factor B and C3). These data suggest that activation of alveolar macrophages may contribute to the development of pathophysiological changes in patients with smoke inhalation (SI) and particularly those with smoke inhalation and burns (SB).

Burns↗
PubMed1991

The efficiency of a flight muscle from the locust Schistocerca americana.

1. The efficiency of the metathoracic tergosternal muscle of the locust Schistocerca americana was examined by simultaneously measuring work output from the muscle and oxygen consumption by the muscle. The work output was determined using the work-loop technique in which the muscle is subjected to periodic strain and to phasic stimulation in the strain cycle. The area of the loop formed by plotting muscle force against muscle length over a cycle is the net work output for that cycle. 2. The tergosternal muscle is a synchronous, parallel-fibred muscle containing two motor units with similar contraction kinetics. The average twitch rise time (30 degrees C) was 15 ms, the twitch duration (to 50% relaxation) was 26 ms, and the peak twitch tension with both units active was 73 kN m-2. The maximum mechanical power output during sinusoidal shortening at 20 Hz with both motor units active and stimulated once per cycle averaged 37 W kg-1. 3. The overall efficiency of the tergosternal muscle averaged 6.4% (range 4-10%) where efficiency is defined as the ratio of the net work done (20 Hz sinusoidal strain, 1 stimulus per cycle, optimum strain amplitude and stimulus phase) to the caloric equivalent of the oxygen consumed. The efficiency was independent of the duration of the test period (examined range = 10-30 s) and the same when both motor units were active as when only one was stimulated. 4. Stimulating the muscle with two stimuli per cycle (interstimulus interval = 6 ms) increased the work per cycle by about 13% above that with single stimuli per cycle, but the muscle fatigued more rapidly and after 15-25 s the power output was less with two stimuli per cycle than with one. The efficiency with two stimuli per cycle was slightly less than that with one shock per cycle. 5. The oxygen consumption during normal work cycles at 20 Hz with optimum stimulus phase and strain was greater by about 15% than the oxygen consumption during isometric contractions at the same frequency.

Animals↗
PubMed1990

Munchausen syndrome by proxy presenting as a developmental disability.

Munchausen syndrome by proxy (MSBP) is a form of child abuse in which a parent falsifies illness in a child by fabricating or producing symptoms and presenting the child for medical care while disclaiming knowledge as to the cause of the problem. This report presents the case history of a child diagnosed with MSBP who was portrayed as having multiple developmental disabilities by her mother. Three elements of the case are noteworthy. The emphasis by the mother on multiple developmental disabilities has not been reported. The complexity of this case is unusual and may reflect the complexity of the mother's psychopathology. The interdisciplinary team evaluation was instrumental in making the diagnosis.

Cerebral Palsy↗
PubMed1989

Stimulant medication therapy in the treatment of children with attention deficit hyperactivity disorder.

Despite the tremendous research advances that have increased our knowledge regarding the pharmacodynamics, clinical pharmacology, pharmacokinetics, and adverse effects of stimulant medications in the treatment of children with ADHD, our knowledge is yet incomplete. Perhaps the most central unresolved issue concerns our understanding of the pathogenesis, pathophysiology, and diagnosis of ADHD. This review has touched briefly on the controversy and confusion surrounding this issue. Although our understanding of the use of stimulant medications in this disorder is similarly incomplete, a review of the literature does allow certain conclusions to be made that are helpful to the practitioner. 1. Stimulant medications are an effective treatment modality for most children with ADHD. Short-term efficacy is well documented, and long-term outcome may be improved when stimulants are used with other therapeutic strategies. Stimulants in and of themselves are not a panacea. 2. It is impossible to predict which children will have a favorable response to stimulant medications and which children may have a placebo response. The use of individual single-blind medication trials is a practical solution to this problem and should be considered for all children who are candidates for stimulant therapy as a means for preventing overuse or inappropriate use of these medications. 3. The precise mechanism of action of stimulants is not yet completely understood, but stimulants appear to exert their therapeutic effects through their influence on multiple neurotransmitters in the catecholamine, dopamine, norepinephrine axis in the central nervous system. 4. The three major stimulants--methylphenidate, dextroamphetamine, and pemoline--appear to be equally efficacious, although methylphenidate has emerged as the most commonly used and most studied drug. Because of its potential for causing liver toxicity, pemoline has remained a second-line medication. 5. The three major stimulants appear to have somewhat different mechanisms of action so that failure of a patient to respond to one medication does not mean that he or she will not respond to another. 6. The recommended starting doses for the stimulants are 0.3 mg per kg of methylphenidate, 0.15 mg per kg of dextroamphetamine, and 37.5 mg of pemoline. There is a great deal of individual variability in dose response, so doses must be titrated for optimal effects in each child. Sustained release preparations are much more expensive than regular preparations and may be less effective. 7. There is no evidence that stimulants have any effect on ultimate adult height. 8. Although relatively uncommon, motor tics have been observed in children on stimulants, and all children on stimulants need to be carefully monitored for the development of tics. (ABSTRACT TRUNCATED AT 250 WORDS)

Attention Deficit Disorder with Hyperactivity↗
PubMed1989

Serological cross-reactivity among chlamydial strains in a family outbreak of psittacosis.

Three members of a family of nine persons contracted psittacosis with severe pneumonia, respiratory failure, delirium, hepatitis and renal involvement. A newly purchased cockatiel was probably the primary source of infection but person-to-person transmission is likely to have taken place between twin brothers who shared a bedroom, one of whom had no direct contact with birds. Type-specific chlamydial serological tests identified the infecting agent as Chlamydia psittaci. The highest titres in the initial samples of serum from the patients, however, were to C. psittaci TWAR (Taiwan Acute Respiratory) and serological cross-reactivity among chlamydial strains was demonstrated. This study of a clearly defined outbreak of psittacosis provides useful information for those undertaking larger population surveys of chlamydial disease and emphasises the need for detailed serological investigation of cases.

Adolescent↗
PubMed1989

Long term haemodynamic, pulmonary function and symptomatic effects of pirbuterol in COPD.

Haemodynamic studies at rest and during exercise together with radionuclide ventriculography, pulmonary function and clinical well-being assessment were evaluated in ten patients with COPD and secondary pulmonary hypertension (mean PAP 25 mm Hg), before and after 6 months therapy with pirbuterol 20 mg thrice daily. Despite the continued pharmacological action of pirbuterol on the heart and systemic circulation during peak pirbuterol levels at 6 months, no significant effect on the pulmonary circulation was observed. Seven patients reported an improvement in the level of fatigue, the partial pressure of carbon dioxide fell significantly (6.5 +/- 0.9 to 6.1 +/- 0.9 kPa: P less than 0.01) and there was a slight bronchodilator effect [forced expiratory volume in 1s (FEV1) 0.60 +/- 0.18 to 0.71 +/- 0.2 1s-1: P less than 0.02] after 6 months. The drug was generally well tolerated but three patients with pre-existing biliary tract disease developed obstructive jaundice.

Aged↗
PubMed1988

Management of asthma in hospital: a prospective audit.

In a prospective study of management of asthma in hospital patients with acute asthma admitted to a single hospital over a calendar year were surveyed. Altogether 157 out of 194 admissions (81%) were studied. The patients (16 of whom had been admitted twice and one three times) were interviewed at home about two weeks after discharge, and their hospital records were reviewed. When interviewed an appreciable proportion of patients said that their asthma had been poorly controlled after their discharge from the hospital: 54 reported regular sleep disturbance due to wheeze, 78 tightness of the chest in the morning, and 77 wheeze after climbing one flight of stairs. Patients had been described on admission as having had symptoms of deteriorating asthma for a median of three days. Closer questioning of 71 patients, however, elicited that 50 had had regular symptoms indicating poor control for weeks or months. Most patients did not know how their drugs worked, and many did not have an appropriate plan of action in the event of a further attack. In all the cases studied 114 patients were treated with oral corticosteroids, only 70 had had their previous maintenance treatment increased at the time of discharge, and 107 had a follow up appointment booked for an average of three and a half weeks after discharge. These findings show that undersupervision and undertreatment of patients with asthma are common and not confined to those dying of the condition.

Asthma↗
PubMed1988

Differences in hospital asthma management.

Asthma management was audited prospectively for one year in a large teaching hospital. Full details were available on 77% of all patients admitted, or readmitted, with asthma during that year (150 of 195 admissions). 64 patients were admitted to general wards with a special interest in respiratory medicine, and 86 to general wards without this specialist interest. Cases in the two groups were similar in terms of age, previous severity of asthma, previous treatment, and initial pulse rate. Fewer cases in the non-specialist group were treated with oral corticosteroids (67%, vs 83%), had regular peak flow recordings (42%, vs 73%), or were given return appointments (56%, vs 92%); and fewer had their regular inhaled therapy increased after discharge (28%, vs 55%). At interview 13 days later, more patients from the non-specialist group reported sleep disturbance (41%, vs 23%), morning chest tightness (55%, vs 37%), ow wheeze on 1 flight of stairs (58%, vs 34%). 20% of first admissions in the non-specialist group were readmitted within the year, compared to 2% of the group treated on wards with a specialist interest in respiratory medicine. These data suggest that the intensive management of asthmatic patients, practised in respiratory units, prevents much unnecessary morbidity.

Acute Disease↗
PubMed1988

Bronchial hyperreactivity in patients who cough after receiving angiotensin converting enzyme inhibitors.

Angiotensin converting enzyme inhibitors cause cough in some patients, but the mechanism of this effect is not known. Six patients in whom these inhibitors had caused cough and a further two patients in whom they were suspected to have caused worsening of bronchial asthma were studied. Nine patients in whom angiotensin converting enzyme inhibitors had not been associated with cough served as controls. In the controls lung function and bronchial reactivity were measured once; for the study patients these and the cough index were measured twice before rechallenge for two weeks with an angiotensin enzyme inhibitor and once afterwards. Rechallenge with drug for two weeks caused a significant decrease in the mean concentration of histamine causing a 35% fall in airways conductance and a significant increase in the cough index. Patients with cough showed bronchial hyperactivity compared with the controls, which increased after rechallenge with the inhibitors. Cough associated with converting enzyme inhibitors may be a variant of the cough in asthma.

Adult↗
PubMed1988

Apical pulmonary fibrosis in psoriasis.

Apical pulmonary fibrosis has been established as a non-articular complication of ankylosing spondylitis. Although psoriasis is frequently associated with arthropathy and spondylitis, there is only one previous report of apical fibrosis occurring in a patient with psoriasis. We report two patients with psoriasis complicated by apical pulmonary disease in whom extensive investigations were negative.

Aged↗