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Biomedical subjects

T W Chick

Publications and source records attributed to T W Chick.

50 records · Page 3Linked to original sources
PubMed1977

Pulmonary dysfunction after lymphangiography.

Pulmonary function tests were done on 15 patients before and after bipedal lymphangiography. Lymphangiography was associated with an approximate 10 per cent reduction in lung volume. This phenomenon persisted for 48 to 72 hours. The probable mechanism for this reduction is closure of terminal airways or alveolar ducts or both and is reversible by beta-adrenergic drugs. The reduction does not correlate with the severity of pre-existing pulmonary disease. The degree of pulmonary impairment can be assessed roughly by measurement of the vital capacity. An operation can be performed safely 3 to 5 days after lymphangiography.

Aged↗
PubMed1977

Comparative bronchodilator responses to atropine and terbutaline in asthma and chronic bronchitis.

We have compared bronchodilator responses to atropine and terbutaline in 39 chronic bronchitics and 16 stable asthmatics. Fasting subjects were given either 1.05 mg atropine of 5.0 mg terbutaline orally. Pulmonary function was assessed using the peak responses, namely: three 60-minute intervals for terbutaline and three 30-minute intervals for atropine. A subgroup of five reactive bronchitis patients was given a placebo with no response. Areas under the percent response-time interval curve were compared. Both patient groups responded to the same degree to atropine and terbutaline with respect to reduction of airway resistance. However, the FEV1 and V50 responses to terbutaline were markedly enhanced compared to atropine in the asthmatics while equal to the atropine response in the bronchitis patients. Thus, atropine appears to exert its effect upon both large and small airways in bronchitis, but predominantly on large airways in asthma. The results are consistent with a state of enhanced vagal tone in small airways in bronchitis compared to asthma, but other explanations are conceivable.

Airway Resistance↗
PubMed1977

Apparent theophylline half-life fluctuations during treatment of acute left ventricular failure.

The administration of theophylline in a 63-year-old man with arteriosclerotic heart disease and chronic bronchitis is discussed to illustrate the pharmacokinetics of theophylline in an abnormal host state. The case demonstrates that clearly acute congestive heart failure and its treatment may dramatically affect the kinetics of theophylline elimination. Possible explanations for this phenomenon are presented, and the therapeutic implications are discussed.

Administration, Oral↗
PubMed1976

Pulmonary dysfunction in systemic lupus erythematosus without pulmonary symptoms.

Pulmonary function was measured in a group of 28 patients with systemic lupus erythematosus (SLE) who were free of pulmonary involvement at the time of the study. When compared with age and sex matched controls, the SLE patients had a pattern of restriction with reduced lung volumes and vital capacity. Diffusing capacity was reduced in proportion to the reduction in lung volume. This is felt to be most compatible with inapparent pleural thickening resulting in impaired lung expansion. There was no evidence of airway obstruction on maximal expiratory flow-volume curves. The effect of cigarette smoking in the SLE patients was a reduction in flows at low lung volumes, which was indistinguishable from the effects in the control smokers. Both SLE and control smokers had a significant reduction in DL/VA when compared with control nonsmokers. Pulmonary function was not influenced by the presence of renal disease.

Female↗
PubMed1975

The effect of nitroglycerin in gas exchange on chronic obstructive pulmonary disease.

Nitroglycerin was administered to a group of 11 patients with chronic obstructive pulmonary disease in a dose of 0.4 mg sublingually. Arterial blood gases and blood pressure and pulse were measured at 5-min intervals for 30 min after nitroglycerin. There was a slight decrease in arterial O2 tension for the duration of the study; the maximal change was from a mean pre-nitroglycerin value of 53.5 mm Hg to 50.3 mm Hg at 20 min. In addition, there was a slight reduction in arterial CO2 tension and bicarbonate for 25 min. It is postulated that decreased O2 transport (due to increased hypoxemia and probably decreased cardiac output) plus hypocapnia were a sufficient stimulus to raise blood lactate. It is recommended that in patients receiving nitroglycerin who have obstructive airway disease, attention be directed toward the effect on arterial blood gases.

Acid-Base Equilibrium↗
PubMedDate not supplied

Evaluation of the relationship between heart rate and ventilation for epidemiologic studies.

Estimation of pulmonary exposure and dose in air pollution epidemiology has been impaired by the lack of methods for directly measuring ventilation in ambulatory subjects. Heart-rate monitoring offers an approach to estimate ventilation by using ventilation-on-heart-rate (VE-HR) regressions established during exercise testing to estimate ventilation in the field. Conventional methods and protocols for testing were used to evaluate the relationship between VE and HR during three tasks: (1) exercising on a cycle ergometer, (2) lifting, and (3) vacuuming. The relationship between VE and HR was curvilinear and was best fit with linear regression models, using a natural log transformation of VE. Considerable interindividual variability in slopes and intercepts was observed across all types of exercise tests. The variability about the fitted regression lines for individual subjects was minimal; for example, individual R2 values for the maximum exercise test on 15 men ranged from 0.90 to 0.99 (mean = 0.97). The regression slopes established during upper-body exercise were greater by approximately 30%, relative to those derived in lower-body exercise (paired t test, p < .001). However, VE-HR regression slopes derived from tests in which progressively increasing workloads were used were comparable to those obtained during variable and nonprogressive protocols. These findings indicate that predictive accuracy is maximized by deriving VE-HR regressions for individual subjects and for both lower- and upper-body activities.

Adolescent↗
PubMedDate not supplied

Oronasal distribution of ventilation at different ages.

The route of breathing, oral or nasal, is a determinant of the doses of inhaled pollutants delivered to target sites in the upper and lower respiratory tracts. We measured partitioning of ventilation, using a divided oronasal mask during a submaximal exercise test, in 37 male and female subjects who ranged in age from 7 to 72 y. The following four patterns of breathing were evident during exercise: (1) nasal only (13.5%), nasal shifting to oronasal (40.5%), oronasal only (40.5%), and oral only (5.4%). Children (i.e., 7-16 y of age) displayed more variability than adults with respect to their patterns of ventilation with exercise. Young adults (i.e., 17-30 y of age) who initially breathed nasally with exercise switched to oral ventilation at a lower percentage of the previously measured maximum ventilation (10.8%) than older subjects (31.8%). The partitioning of ventilation between the nasal and oral routes follows complex patterns that cannot be predicted readily by the age, gender, or nasal airway resistance of the subject.

Adolescent↗
PubMedDate not supplied

The effect of nitroglycerin on gas exchange, hemodynamics, and oxygen transport in patients with chronic obstructive pulmonary disease.

The present study was designed to investigate pharmacological vasodilation in patients with chronic obstructive pulmonary disease (COPD). This may have long-term therapeutic implications. Sublingual nitroglycerin (GTN) was administered to 16 patients with COPD and no evidence of organic heart disease (except one patient) in an attempt to determine severity of the decrease in arterial oxygenation. Gas exchange and hemodynamic studies were performed before and after GTN. Alverolar-arterial O2 tension gradient increased 5 mm Hg, arterial PO2 decreased 2 mm Hg, and cardiac output decreased from 4.36 to 3.85 liters/min. There was a decrease in pulmonary artery pressures, but pulmonary vascular resistance did not change. Total O2 transport (the product of cardiac output and arterial O2 content) decreased, due mainly to a decrease in cardiac output. From these studies we conclude that GTN significantly decreases O2 transport in patients with COPD and normal left ventricular function; this decrease is due mainly to a reduction in cardiac output. Impairment of gas exchange is slight. Based on these considerations pharmacological vasodilation with nitroglycerine in COPD is probably not warranted.

Adult↗