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Biomedical subjects

M Simmons

Publications and source records attributed to M Simmons.

At least 19 recordsLinked to original sources
PubMed1992

An evaluation of the esophageal detector device using a cadaver model.

The study was conducted to evaluate the usefulness of an esophageal detector device (EDD) to correctly differentiate between esophageal and tracheal intubation. The study was conducted in the emergency department using 10 recently decreased cadavers (nine males, one female, age range 50-72 years). An 8-mm internal diameter endotracheal tube was placed orally into the trachea, and a second 8-mm ID tube was placed orally into the esophagus. Both tubes extended the same distance from the mouth, and the cuffs were not inflated. After placement of the tubes, the EDD was used by advanced life support providers (physicians, nurses, paramedics, and respiratory therapists) to determine if each tube was in the trachea or the esophagus. The persons who assessed the tube placement were not present when the tubes were placed into the cadavers. Multiple evaluators were allowed for each cadaver, but each evaluator only participated one time for each cadaver. The bulb of the EDD was squeezed by the evaluator, who then attached it to the endotracheal tube and rated the bulb inflation as immediate inflation, delayed inflation, or no inflation. Prior to participation in the study, evaluators were instructed in the use of the EDD. There were a total of 45 trials performed on the cadavers (median, four evaluations/cadaver, range, one-eight). For the tracheal tube, the EDD inflated immediately in all cases; it was thus 100% correct in identification of tracheal intubation. For the esophageal tube, the EDD did not inflate in 44 cases, and in one case it filled with vomitus; it thus correctly identified esophageal intubation in all cases.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1992

Respiratory effects of cocaine freebasing among habitual cocaine users.

Smoking of alkaloidal cocaine ("crack") has become increasingly prevalent in our society. Recent evidence suggests that crack smoking can cause acute respiratory symptoms, abnormalities in lung function and, in some instances, severe, life-threatening acute lung injury. To evaluate further the relationship between frequent cocaine smoking and respiratory symptoms and lung dysfunction, we studied a sample of 177 heavy, habitual smokers of freebase cocaine (mean 6.6 gm/wk for an average of 27 months) with or without concomitant smoking of tobacco and/or marijuana. Results in this sample were compared with those in a control sample of 75 age-, sex- and race-matched nonsmokers of cocaine who did or did not also smoke tobacco and/or marijuana. After controlling for the use of other smoked substances, heavy, habitual cocaine smoking was associated with the following: (1) a high frequency of acute respiratory symptoms (cough, black sputum, chest pain) in temporal association with freebase use; (2) an obstructive ventilatory abnormality involving the large airways; and (3) a mild but significant impairment in the diffusing capacity of the lung. These findings suggest that heavy, habitual crack smoking produces (1) respiratory tract injury manifested by acute respiratory symptoms and evidence of chronic airflow obstruction in large airways, and (2) an abnormality in diffusion of gas at the alveolar-capillary level. The mechanism of the diffusion defect is unknown but could reflect damage to the alveolar-capillary membrane. Further study of the magnitude, persistence, reversibility, mechanism and clinical significance of the abnormality in diffusing capacity is needed.

Adult↗
PubMed1992

The effect of two intraoperative heat-conserving methods on orthopedic patients receiving regional and general anesthesia.

Postoperative hypothermia is a serious complication of surgery. The best way to prevent postoperative hypothermia is to prevent perioperative heat loss. The purpose of this study was to compare the efficacy of Thermadrape (O.R. Concepts, Inc., Roanoke, TX), a heat-retaining surgical covering, with cotton blankets in maintaining core body temperature for patients receiving general or regional anesthesia. One hundred seventeen patients having hand, wrist, or elbow surgery were covered with either cotton blankets or Thermadrape covering throughout the perioperative period. Core body temperature was measured using a tympanic membrane device (FirstTemp, Intelligent Medical Systems, Carlsbad, CA) preoperatively, on PACU admission, and at discharge. Thermadrape covering and cotton blankets were equally effective in conserving body heat. Patients receiving general anesthesia were cooler on PACU admission than those receiving regional anesthesia, regardless of the type of covering. Hospital decisions regarding choice of perioperative heat conservation interventions will be guided by the cost of the intervention as well as efficacy. If overall hospital cost of cotton blankets is greater than that associated with Thermadrape covering, a decision to use Thermadrape covering may be warranted. Important factors for consideration in future research are presented and discussed.

Anesthesia, Conduction↗
PubMed1991

A nebulizer chronolog to monitor compliance with inhaler use.

The Lung Health Study is a 10-center 5-year clinical trial sponsored by the National Heart, Lung, and Blood Institute to evaluate the effectiveness of early intervention in chronic obstructive pulmonary disease (COPD). The specific objectives of the trial are to determine whether the accelerated decline in lung function characteristic of COPD and morbidity due to COPD can be reduced by special intervention at a relatively early stage in the evolution of the disease. Special intervention consists of a smoking-cessation program and the use of an inhaled bronchodilator to suppress airway hyperreactivity. The use of the inhaler canister is monitored every 4 months by canister weighing and, at two of the 10 centers, by an electronic recording device, the Nebulizer Chronolog. Among trial participants assigned the latter device, results from the first 4 months of the study indicate that only 52% of trial participants who were uninformed as to the nature of the chronolog used their inhaler at least twice daily as measured by the chronolog, compared with 87% as determined by self-report. Satisfactory or good compliance was achieved by 52% of these subjects as measured by the chronolog compared with 85% as assessed by canister weighing. Eighteen percent of uninformed participants "dumped" their inhalers within a 3-hour time period, contributing to the inaccuracy of canister weights as an indicator of compliance. Feedback of information to the participants from the chronolog improved the level of compliance and eliminated the "dumping" phenomenon. We conclude that, when accurate determinations of compliance are important, as in a drug trial, objective medication monitors should be considered. Electronic monitoring of inhaler use can provide valuable feedback, which encourages improved compliance.

Adult↗
PubMed1991

Aluminum chloride stimulates the release of endogenous glutamate, taurine and adenosine from cultured rat cortical astrocytes.

Primary astrocyte cultures derived from neonatal rat cerebral cortex were treated for 5 min with 0.5 mM or 5.0 mM AlCl3, and the incubation medium was analyzed by HPLC for the content of released glutamate (Glu), taurine (Tau), serine (Ser) and the nucleoside adenosine (Ade). At 0.5 mM, AlCl3 stimulated Tau release to about 170% of basal levels, but did not affect the release of the other compounds. Treatment with 5.0 mM AlCl3 enhanced the release of Tau, Glu and Ade, to 800%, 1000% and 250%, respectively, but decreased the release of Ser to 70% compared to basal levels. The enhanced release of these neuroactive compounds from astrocytes may contribute to changes in neural transmission known to accompany exposure to aluminum.

Adenosine↗
PubMed1991

Tc-99m HMPAO SPECT imaging of the central nervous system in tuberous sclerosis.

Tc-99m HMPAO was used to evaluate cerebral perfusion in a patient with tuberous sclerosis. The SPECT images demonstrated reduced HMPAO uptake in regions corresponding with MRI-confirmed locations of cortical tubers. These results indicate that the lesions are characterized by vascular perfusion deficits and support the hypothesis that cortical tubers result from developmental abnormalities of the embryonic central nervous system.

Brain↗
PubMed1991

Retrieval analysis of a hydroxyapatite-coated hip prosthesis.

A 61-year-old woman fitted with a hydroxyapatite (HA)-coated macrotexture all-purpose hip prosthesis died three weeks after implantation. The retrieved femoral and acetabular components were examined using contact roentgenograms, the back-scattered mode of the scanning electron microscope, and light microscopy. Newly formed bone was observed in the marrow spaces and along the morselized autograft bone chips, which had been surgically placed in the medullary canal at the time of implantation. New bone was observed along 10% of the HA surface of the femoral component and 20% of the acetabular component. Some bone was also observed connecting the surrounding bone chips to the HA coating. Light microscopy showed the presence of osteoid on 20% of the femoral component and on 40% of the acetabular component. HA coating on total hip prostheses appears to enhance early skeletal attachment, which may be attributed to the osteoconductive properties of the composite.

Durapatite↗
PubMed1990

Skin score. A semiquantitative measure of cutaneous involvement that improves prediction of prognosis in systemic sclerosis.

Cutaneous sclerosis, assessed yearly by a semiquantitative skin scoring technique (sum of 10 body areas, each scored on a scale of 0-3 for tethering, by clinical palpation), and outcome at 10 years were evaluated in 90 systemic sclerosis patients enrolled in a 3-year, prospective drug trial. The inverse relationship of survival to the skin score at study entry (increasing skin score associated with decreasing survival) (P less than 0.003) was more significant than was the relationship found by using classification schemata that rely only on distribution of cutaneous sclerosis. Six-year survival was 40% in patients with entry skin scores greater than or equal to 15 and 73% when skin scores were less than 15 (P less than 0.005). An entry skin score greater than or equal to 15 was associated with a high risk of early fatal renal and cardiac complications.

Adult↗
PubMed1989

Outpatient paediatric dental anaesthesia. A comparison of halothane, enflurane and isoflurane.

One hundred and fifty unpremedicated children who presented for dental extractions were anaesthetised with nitrous oxide and halothane, enflurane or isoflurane. Ventricular arrhythmias occurred only in the halothane group (14%). Respiratory problems and desaturation were significantly more common in the isoflurane group. Induction times differed significantly between the groups halothane less than enflurane less than isoflurane, while recovery time and induction to recovery time were significantly shorter in the enflurane group. We suggest that enflurane is the most suitable agent for anaesthetising these patients.

Ambulatory Surgical Procedures↗
PubMed1988

Decreased serum cotinine levels in smokers of both tobacco and marijuana as compared with smokers of tobacco only.

Serum and salivary cotinine levels were determined in tobacco smokers (n = 125) who smoked only tobacco (n = 47) or who smoked both marijuana and tobacco (n = 78) as part of a field study of the pulmonary effects of heavy, habitual use of marijuana alone or with tobacco. After adjustment for current daily amount of tobacco use and time since the last tobacco cigarette was smoked, the smokers of both marijuana and tobacco were found to have lower levels of cotinine than those who smoked only tobacco, in serum [258 +/- 113 ng/ml (S.D.) and 332 +/- 109, respectively; p = 0.003] and in saliva (331 +/- 170 and 395 +/- 170, respectively; p = 0.058). Serum cotinine showed a significantly negative relationship to the daily amount of marijuana currently smoked (p = 0.026). Possible explanations include inhibition by marijuana component(s) of the enzymes that participate in the conversion of nicotine to cotinine, differences in nicotine absorption patterns between the two groups of tobacco smokers, and acceleration of cotinine metabolism by marijuana smoking. Carefully controlled pharmacokinetic studies, not possible in a large-scale survey such as this one, are required both to confirm the differences in blood cotinine levels observed between the dual smokers and smokers of tobacco only and to define more clearly nicotine-marijuana interactions.

Adult↗
PubMed1987

Longitudinal changes in lung function and respiratory symptoms in progressive systemic sclerosis. Prospective study.

Most patients with progressive systemic sclerosis (PSS) exhibit lung involvement. However, the natural history of lung disease in PSS remains poorly defined. To evaluate lung function over time in PSS, a battery of lung function tests were prospectively performed serially between 1973 and 1982 in 61 patients with PSS. Functional indexes of restriction (vital capacity and total lung capacity) and diffusion impairment (diffusing capacity) showed greater-than-expected annual rates of change. Male subjects showed a trend toward faster declines in forced vital capacity, forced expired volume in one second, total lung capacity, and functional residual capacity and a more rapid increase in static recoil pressure at 90 percent of total lung capacity than did female subjects. Nonsmokers had greater rates of decline in total lung capacity and static lung compliance (but not in forced vital capacity or diffusing capacity) and a greater rate of increase in static recoil pressure than did current and former smokers. Level of lung function at initial study visit, age, race, and chlorambucil therapy had no significant effect on the annual rates of change in lung function, whereas longer duration of disease prior to study entry was associated with a slower annual decrease in lung volumes. Between the first and last visits (mean interval 3.1 years, maximum nine years), the frequency of abnormality in pulmonary function test results showed significant change only in the diffusing capacity (60 percent increasing to 82 percent) and static lung compliance (40 percent increasing to 54 percent), whereas the frequency of respiratory symptoms showed little change. These findings indicate an overall indolent progression of PSS-related lung disease, with substantial individual variability.

Adult↗
PubMed1987

Factor analysis of clinical data from asbestos workers: implications for diagnosis and screening.

Clinical data from 624 asbestos exposed workers were analysed by factor analysis. Fifteen clinical variables were found to reflect several underlying factors: "obstruction," "interstitial disorder," "x ray change," "air tapping," and "age/exposure." Scoring individual subjects along these axes can facilitate identifying early cases and avoiding false diagnosis. The analysis suggests that screening should be multimodal and that radiographic abnormality need not imply physiological impairment.

Asbestosis↗
PubMed1987

Respiratory symptoms and lung function in habitual heavy smokers of marijuana alone, smokers of marijuana and tobacco, smokers of tobacco alone, and nonsmokers.

To evaluate the possible pulmonary effects of habitual marijuana smoking with and without tobacco, we administered a detailed respiratory and drug use questionnaire and/or lung function tests to young, habitual, heavy smokers of marijuana alone (n = 144) or with tobacco (n = 135) and control subjects of similar age who smoked tobacco alone (n = 70) or were nonsmokers (n = 97). Mean amounts of marijuana and/or tobacco smoked were 49 to 57 joint-years marijuana (average daily number of joints times number of years smoked) and 16 to 22 pack-years of tobacco. Among the smokers of marijuana and/or tobacco, prevalence of chronic cough (18 to 24%), sputum production (20 to 26%), wheeze (25 to 37%) and greater than 1 prolonged acute bronchitic episode during the previous 3 yr (10 to 14%) was significantly higher than in the nonsmokers (p less than 0.05, chi square). No difference in prevalence of chronic cough, sputum production, or wheeze was noted between the marijuana and tobacco smokers, nor were there additive effects of marijuana and tobacco on symptom prevalence. We noted significant worsening effects of marijuana but not to tobacco on specific airway conductance and airway resistance (tests of mainly large airways function) in men and of tobacco but not of marijuana on carbon monoxide diffusing capacity and on closing volume, closing capacity, and the slope of Phase III of the single-breath nitrogen washout curve (tests reflecting mainly small airways function) (p less than 0.03, two-way ANCOVA). No adverse interactive effects of marijuana and tobacco on lung function were found.

Adult↗
PubMed1987

Physiologic categorization of asbestos-exposed workers.

Categorization of the pattern of physiologic abnormalities in patients with asbestos-associated disease may be important for clinical, compensation, and epidemiologic reasons. A population of 658 asbestos-exposed workers was divided into six groups (restrictive, mixed restrictive-obstructive, obstructive, abnormal diffusing capacity, small airway disease, and normal) based upon pulmonary function test results. Use of two commonly employed prediction equations for diffusing capacity produced divergent results. Adjustment of the forced vital capacity for airtrapping based upon measurement of residual volume or of total lung capacity can improve the accuracy of categorization, particularly in smokers. Hence, the process of interpretation of pulmonary function testing should be chosen carefully.

Adult↗
PubMed1987

A comparison of psychotropic drug use between the general population and clients of health and social service agencies.

The purpose of this research was to study the epidemiology of psychotropic drug use among the general population and to draw comparisons to drug use among clients of medical, mental health, and social services in the same jurisdiction. Results showed considerably higher percentages of users for all drug categories among agency clientele. Age and sex differences in drug use replicated previous research in the general population but were noticeably absent among the clients of local services. Notably, the proportion of long-term daily users of minor tranquilizers in the agency population was about three times that of the general population. However, tranquilizer users in the two populations were similar in many respects. Results of the study are discussed in terms of the need for screening for persons with psychotropic drug problems in health and social services.

Adult↗
PubMed1987

Adrenoleukodystrophy: imaging with CT, MRI, and PET.

A patient with adrenoleukodystrophy (ALD) was tested with a series of CT scans, magnetic resonance imaging (MRI), and positron emission tomographic (PET) images. The computed tomographic (CT) scan revealed the classical pattern described in ALD but showed little relation to the clinical presentation and the evolution of the disease. The MRI showed a larger area of abnormality than the one detected with the CT scan and was more sensitive to progression of the disease process. The PET scan done for cerebral blood flow and glucose metabolism showed derangements on gray matter that were not detected with either of the previous tests.

Adrenoleukodystrophy↗
PubMed1985

Potassium supplementation in hypertensive patients with diuretic-induced hypokalemia.

Changes in potassium balance have been found to have variable effects on the blood pressure of animals, and the administration of potassium supplements has been reported to lower the blood pressure of normokalemic hypertensive patients. To assess the effect of potassium repletion in hypokalemic hypertension, we administered either potassium chloride, 60 mmol per day, or placebo tablets, each for six weeks, in a randomized, double-blind, crossover trial to 16 hypertensive patients who had diuretic-induced hypokalemia and who continued to take a constant amount of diuretic. We selected patients whose control serum potassium levels were below 3.5 mmol per liter. In association with an average rise in the serum potassium concentration of 0.56 mmol per liter, the mean blood pressure fell by an average of 5.5 mm Hg (P = 0.004), with at least a 4 mm Hg fall observed in 9 of the 16 patients. The fall in blood pressure correlated with a fall in plasma renin activity (r = 0.568, P = 0.043) but not with changes in plasma aldosterone levels or other variables. We conclude that short-term potassium supplementation that ameliorates diuretic-induced hypokalemia may induce a significant fall in blood pressure.

Adult↗