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M S Simmons

Publications and source records attributed to M S Simmons.

50 records · Page 3Linked to original sources
PubMed1984

Hypoxia-altitude simulation test. Evaluation of patients with chronic airway obstruction.

Increasing hypoxia with altitude ascent is a potentially serious problem for patients with hypoxemic chronic airway obstruction (CAO) at sea level. We developed a hypoxia-altitude simulation test (HAST) to assess acute cardiopulmonary responses to the inhalation of hypoxic gas mixtures (equivalent to the inspired oxygen tension (PO2) present at 5,000, 8,000, and 10,000 feet above sea level) alone and in combination with supplemental oxygen (O2). Twenty-two subjects with stable normocapnic CAO were studied at sea level with a computer-based system that measured on-line, breath-by-breath resting ventilatory and gas exchange variables. Subjects breathed 20.9% (baseline), 17.1, 15.1, 13.9, and 20.9% (recovery) O2, and measurements were obtained once a "steady state" was reached at each level. Steady-state arterial PO2 (PaO2) and O2 saturation, alveolar PO2, and alveolar-to-arterial PO2 gradient decreased markedly during successive hypoxic levels, whereas arterial carbon dioxide tensions decreased only modestly. Minute ventilation and heart rate during 13.9% O2 increased only 12 and 10% above baseline. Ten subjects had asymptomatic cardiac arrhythmias during the HAST. Supplemental O2 significantly improved nearly all physiologic indexes. Sea level PaO2 best predicted acute, resting altitude PaO2. Sea level PaO2 values of 68 and 72 mmHg successfully classified more than 90% of the subjects with a PaO2 greater than 55 mmHg at 5,000 feet and a PaO2 greater than 55 mmHg at 8,000 feet, respectively. A regression equation and nomogram were derived to estimate PaO2 at altitudes between 5,000 to 10,000 feet in patients with normocapnic CAO.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1983

Respiratory symptoms of flight attendants during high-altitude flight: possible relation to cabin ozone exposure.

The smaller size and lighter weight of the Boeing 747SP aircraft, introduced into passenger service in 1976, permitted higher-altitude flight than older commercial aircraft and thus potentially greater ozone exposure for those of board. Concerned flight attendants distributed questionnaires relating to symptoms experienced on the Boeing 747SP and/or conventional 747 aircraft to Los Angeles- and New York-based flight attendants. Respondents reported symptoms by frequency and severity and by in-flight and after-flight occurrence. Based on the assessment of three health scientists as to ozone-relatedness, the frequency of "definite" and "probable" ozone-related symptoms of any severity reported by both groups of attendants was significantly associated with 747SP flights (chi-squares: P less than 0.05). After-flight symptoms significantly associated with 747SP experience, although fewer in number than in-flight symptoms, were all in the scientists' "definite" category. In 21 flight attendants who complained of moderate to severe symptoms during 747SP flights, a battery of pulmonary function tests performed approximately two weeks after their last 747SP flight failed to reveal abnormalities. The symptom questionnaire results are consistent with possible exposure of cabin attendants to toxic levels of ozone during the higher-altitude flights of the Boeing 747SP compared to conventional 747 aircraft.

Aerospace Medicine↗
PubMed1982

Residents' training goals in respiratory knowledge and skills: perspective of three parties.

Medical residents, full-time respiratory teaching staff, and community-based doctors rated the importance of fifty-five respiratory training goals involving knowledge and skills necessary for the future practices of all medical residents. Residents also rated their perceived preparedness in these training areas. Intra- and inter-group analyses indicated that residents agreed more often, and consistently assigned more importance (94% of goals) to the training goals, than did the teachers and doctors. Although the residents considered themselves prepared for 69% of the training goals, they also had moderate intra-group disagreement. These results may reflect variable training experiences and/or institutional practices, but areas of less than adequate preparation were identified and can be corrected. The other two groups were in general agreement except regarding some clinical skills. This study offers possible explanations for the group responses and indicates the potential benefit for groups to discuss, identify, and survey training goals.

California↗
PubMed1982

The UCLA population studies of chronic obstructive respiratory disease. 5. Agreement and disagreement of tests in identifying abnormal lung function.

The relative sensitivity and specificity of symptoms, spirometry, the flow-volume (FV) curve, the single-breath nitrogen test (SBNT), and specific airway conductance (SGaw) were estimated by cross comparison of these tests with the FEV1/FVC ratio and other tests in 1,201 residents of Los Angeles. Spirometry and the flow-volume curve were estimated to be the most sensitive, yet reasonably specific composite measures, and FEV1/FVC and V75 to be the most sensitive individual indices. Among current smokers, FEV1/FVC was more frequently abnormal (23 percent) than FEF25-75% (16 percent), showed higher concordance with an abnormal FEF25-75% (88 percent), and identified a greater percentage of individuals as abnormal when the FEF25-75% was normal (9 percent) than vice versa. SGaw and SBNT showed a poor concordance with FEV1/FVC and identified more individuals as abnormal who had a normal FEV1/FVC. Although the proportion of current smokers with productive cough was relatively high (26 percent), none of the function tests showed a reasonable concordance with this symptom. These findings suggest that: 1) spirometry, the flow-volume curve, V75 and FEV1/FVC are relatively sensitive and specific indicators of respiratory impairment; 2) spirometry and the FV curve provide similar but not completely overlapping information; 3) SGaw and SBNT yield different (or less specific) information than the other tests; and 4) effects of cigarette smoking identified by productive cough are different from those identified by other tests.

Adult↗
PubMed1981

Survey of hospital doctors' training goals in diagnosis and management of pulmonary diseases.

Although subspecialty training goals for junior hospital doctors have not been evaluated, they are potentially useful for assessing clinical competence. A questionnaire was sent to medical residents, full-time pulmonary teaching staff, and community-based physicians who were asked to rate the importance of diagnosing and managing selected pulmonary diseases for the future practices of young hospital doctors. The latter also rated their perceived preparedness for the same training goals. Generally good intra- and intergroup agreement about the relevance of most of the training goals was observed, although the hospital doctors rated a greater number of items to be more important than did the two other groups. This finding may be attributed to institutional influences and to many clinical abilities expected of all physicians. Immunological or fibrotic and paediatric respiratory disorders were rated least important by most respondents. The hospital doctors disagreed on the basis of the distribution of their ratings about their preparedness for the same goals, which probably reflects varying training experiences and background. The process of developing general professional training goals in a subspecialty requires discussion, identification, and consensus to identify and potentially correct areas of weakness, with allowance for institutional training patterns. A survey such as described in this study can provide data that can help measure clinical competence and support or define curricular changes.

California↗
PubMed1980

Respiratory status of seventy-four habitual marijuana smokers.

Previous studies of the long-term effects of habitual marijuana smoking on respiratory status and lung function have yielded conflicting results. In the present study, lung function tests obtained in 74 regular marijuana smokers (duration of smoking > two-five years; frequency of smoking three days/week to several times/day) who denied intravenous narcotic drug abuse were compared with similar tests performed in two groups of control subjects. One group consisted of individuals tested in a mobile laboratory who were computer-matched to the marijuana smokers for anthropometric characteristics and quantity and duration of tobacco smoking; the other group was comprised of 41 nonsmokers of marijuana who were tested in the same laboratory as the marijuana smokers. Paired and unpaired t analyses revealed lower values for specific airway conductance (-0.07 to -0.08 +/- 0.02; P < 0.001) in the marijuana smokers compared with either group of control subjects, but no differences in spirometric indices, closing volume or delta N2 750-1250. When non-tobacco smoking marijuana users (n = 50) were matched with either non-tobacco smoking or tobacco smoking control subjects, significant differences were again noted in specific airway conductance (P < 0.001) but not in spirometric tests, closing volume or delta N2 750-1250. These results suggest that habitual smoking of marijuana may cause mild, but significant, functional impairment predominantly involving large airways which is not detectable in individuals of the same age who regularly smoke tobacco. The clinical implications of these findings await further study.

Adult↗
PubMed1978

Biorhythm theory and asthma.

The hypothesis that bronchial asthma might follow a biorhythmic pattern was tested in 25 asthmatics with moderate to severe obstruction who completed daily diaries of respiratory symptoms and medication use. Biorhythm cycles (for 23-, 28- and 33-day periods) were calculated. Analysis of scores of medication use or respiratory symptomatology failed to demonstrate any relationship between asthma and biorhythm cycles or any other periodicity.

Adolescent↗
PubMedDate not supplied

Relationship between acute ozone responsiveness and chronic loss of lung function in residents of a high-ozone community.

We hypothesized that acute respiratory responsiveness to ozone predicts chronic lung injury from repeated exposure to ozone-containing air pollution. We tested this hypothesis in 164 middle-aged nonsmoking residents of an ozone-polluted community who underwent lung-function measurements during 1986 and 1987 (i.e., time 3). The time-3 study was a follow up of more comprehensive studies conducted in 1977-1978 (time 1) and in 1982-1983 (time 2). In contrast to the apparent rapid (i.e., approximately 60 ml/y) decline in lung-function measurements between times 1 and 2, our subjects showed little change in forced vital capacity (FVC) or forced expired volume in 1 s (FEV1.0) between times 2 and 3, and they experienced a normal decline between times 1 and 3. A subgroup (n = 45) underwent 2-h laboratory ozone exposures to 0.4 ppm ozone, accompanied by intermittent exercise, and they experienced mild acute reductions in FEV1.0 and FVC, but there was little change in bronchial responsiveness to methacholine. Individual acute responses to laboratory ozone were not correlated with individual long-term changes between times 1 and 3. In summary, the results did not support our initial hypothesis, and they did not confirm rapid function decline in nonsmokers chronically exposed to ozone-containing air pollution.

Adult↗