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Biomedical subjects

C A Keller

Publications and source records attributed to C A Keller.

13 recordsLinked to original sources
PubMed1988

Effect of posture, hydralazine, and nifedipine on hemodynamics, ventilation, and gas exchange in patients with chronic obstructive pulmonary disease.

A transient relationship between change in cardiac output (CO) and ventilation and a steady-state relationship between VCO2 and ventilation has been documented. We sought to evaluate the steady-state relationship between CO, and minute ventilation (VE) after positional change and after vasodilator administration in 24 patients with chronic obstructive pulmonary disease (COPD) and mild pulmonary hypertension. Cardiac output was 25% higher (p = 0.003) and VE was 25% lower (p = 0.0001) in the supine position. The change in VE showed a strong correlation with the change in VCO2 (r = 0.693; p = 0.0004), but not with the change in CO. Twelve patients received hydralazine 200 mg orally over 24 h, and 12 patients received nifedipine as a single 10-mg oral dose. Cardiac output increased from 5.05 +/- 1.25 L/min to 6.91 +/- 2.07 L/min (p = 0.008) after hydralazine and increased from 4.34 +/- 1.47 L/min to 5.85 +/- 2.15 L/min (p = 0.001) after nifedipine. Minute ventilation increased from 14.8 +/- 3.0 L/min to 17.3 +/- 4.4 L/min (p = 0.008) after hydralazine, but did not change after nifedipine. The change in VE showed a strong correlation with the change in VCO2 after hydralazine (r = 0.889; p = 0.0004) and after nifedipine (r = 0.756; p = 0.005), but did not correlate with the change in CO. These data demonstrate that the change in VE that accompanies positional change or vasodilator administration in patients with COPD is strongly correlated with the change in VCO2 but not with the change in CO when measured under steady-state conditions.

Carbon Dioxide↗
PubMed1987

Intramuscular imipenem/cilastatin for treatment of mild and moderately severe bacterial infections.

The efficacy and safety of intramuscularly administered imipenem/cilastatin was studied in 70 patients with mild or moderately severe bacterial infections (skin and soft tissue infections, respiratory tract infections, urinary tract infections and pelvic infections). Doses of imipenem/cilastatin ranged from 0.5 to 0.75 g twice daily. Fifty-five patients were evaluable for bacteriological efficacy; in the remaining 15 patients no pathogens were isolated or susceptibility data were lacking. MIC50 and MIC90 of imipenem were 0.12 mg/l and 0.5 mg/l, respectively, for Gram-negative pathogens isolated and 0.25 mg/l and 0.5 mg/l, respectively, for Gram-positive pathogens. Only one strain (a Flavobacterium odoratum) was resistant to imipenem. Clinical cure and bacteriological elimination was achieved in 94% of evaluable patients while 3% showed marked clinical improvement. Two patients were considered therapeutic failures. No clinical adverse effects were noted. Abnormal liver transaminases were recorded in 23% of the patients and 11% developed eosinophilia. In no patient was imipenem/cilastatin discontinued due to adverse effects. It is concluded that intramuscular imipenem/cilastatin in these patients was well tolerated and efficacious.

Adolescent↗
PubMed1986

Pulmonary hypertension in chronic obstructive pulmonary disease. Multivariate analysis.

The severity of pulmonary hypertension was evaluated by right cardiac catheterization in 89 patients with stable chronic obstructive pulmonary disease, both at rest and during maximum treadmill exercise. Thirty-one patients were found to have pulmonary hypertension at rest, defined as a mean pulmonary arterial pressure of 20 mm Hg or more. Although the remaining 58 patients had normal mean pulmonary arterial pressure at rest, three developed pulmonary hypertension during exercise (mean pulmonary arterial pressure greater than or equal to 35 mm Hg). Multiple anthropometric, spirometric, radiographic, and gas-exchange variables were analyzed and correlated with the hemodynamic data to define their value in predicting mean pulmonary arterial pressure. While arterial oxygen pressure (PaO2) at maximum exercise was the variable most highly correlated with resting mean pulmonary arterial pressure (r = -0.67), stepwise multiple linear regression analysis indicated that measurement of the diameter of the right descending pulmonary artery and arterial carbon dioxide tension (PaCO2) also contributed to the prediction of mean pulmonary arterial pressure. Spirometric indices of airflow obstruction, hyperinflation, and the diffusing capacity of the lung for carbon monoxide correlated poorly with the severity of pulmonary hypertension and consequently were not useful predictors of mean pulmonary arterial pressure. The threshold criteria of a PaO2 less than 60 mm Hg or a PaCO2 more than 40 mm Hg were reasonably accurate for a diagnosis of pulmonary hypertension. These arterial blood gas criteria were superior to the spirometric and radiographic variables examined in predicting pulmonary hypertension prior to the development of clinically overt cor pulmonale.

Aged↗
PubMedDate not supplied

Morbidity studies of workers exposed to whole body vibration.

Insurance claims for medical services submitted on behalf of a group of workers in the construction industry were collected over a 20-month period. The morbidity experience of those workers exposed to whole body vibration was contrasted with that of an unexposed control group eligible for benefits under the same plan. Using Mantel-Haenszel adjustment for age and experience, a significantly elevated relative risk was found among the exposed group in three of the thirty disease categories studied. In no disease category did the control group possess a significantly higher risk of requiring medical services. A striking proportion of the disease categories showed an initial increase in risk for exposed workers followed by a decrease with experience. This pattern suggests a selection process in which workers leave exposed-group jobs as they become afflicted with certain disease conditions.

Adult↗