PubMed Health⌕ Search

Biomedical subjects

K Page

Publications and source records attributed to K Page.

58 records · Page 4Linked to original sources
PubMed1985

Ventricular performance in human hearts aged 61 to 73 years.

The effects of increasing and decreasing cardiac preload by 15% on the left ventricular (LV) performance of 11 carefully screened normal subjects aged 61 to 73 years were examined. Comparisons were made with 11 subjects aged 21 to 28 years. Two-dimensional echocardiograms were obtained before and at the termination of 5 degrees of head-down tilt for 90 minutes and at the termination of graded lower body negative pressure to -40 mm Hg. Heart rates and blood pressures were unchanged after physiologic interventions. Changes in LV end-diastolic and stroke volumes were similar but of a smaller magnitude in the older subjects compared with changes in younger subjects. When LV end-diastolic volumes obtained at each extreme of preload variation were compared, the range of mean change was less in the older (23 ml, 26%) than in the younger subjects (31 ml, 41%). Control LV end-diastolic and end-systolic volumes were greater in the older subjects. This study shows that despite larger control LV volumes, alterations in preload produce changes in the LV end-diastolic and stroke volumes of these older subjects that conform to the normal LV function curve, but that these responses are diminished compared with changes in younger subjects, suggesting an age-related change in diastolic stiffness.

Age Factors↗
PubMed1981

The physiological responses of mild pulmonary impaired subjects while using a "demand" respirator during rest and work.

This investigation determined the cardiorespiratory responses of subjects with normal lung function and exercise tolerance and compared them with subjects with moderate and severe impairment of lung function and exercise tolerance. Comparisons were made during work while wearing an industrial respirator. The respirator was a full-face mask (MSA-ultravue) "demand" breathing type equipped with an inspiratory resistance of 85 mm H2O at 85 L/min air flow and an expiratory resistance of 25 mm H2O at 85 L/min air flow. Physiologically and subjectively the response of the normal and moderately impaired subjects to respirator wear during rest, 35%, 50% and 63% of their maximal workloads were not different. However, when the moderately impaired worked at 63% of their maximum the workload was equivalent to 50% of maximum of the normal subject. Significant differences in the peak flow/pressure ratio of the severely impaired compared to the normals and moderately impaired were found. By relating work performance to the dyspnea index (VI/MBC) it was suggested that the relationship between maximal lung function and maximal work performance needs to be identified both with and without respirators. This relationship may prove suitable in predicting performance during respirator wear.

Adult↗
PubMed1981

Clinical pulmonary function and industrial respirator wear.

This investigation was the initial step in determining a clinical pulmonary test which could be used to evaluate workers as to their suitability to industrial respirator wear. Sixty subjects, 12 superior, 37 normal, and 11 moderately impaired with respect to lung function tests were evaluated with a battery of clinical pulmonary tests while wearing an industrial respirator. The respirator was a full-face mask (MSA-Ultravue) "demand" breathing type equipped with an inspiratory resistance of 85 mm H2O at 85 L/min air flow and an expiratory resistance of 25 mmH2O at 85 L/min air flow. Comparisons of these tests were made between the three groups of subjects both with and without a respirator. It appears that those lung tests which measure the flow characteristics of the lung especially those that are effort dependent are more susceptible to change as a result of respirator wear. Hence, the respirator affects the person with superior lung function to a greater degree than the moderately impaired person. It was suggested that the clinical test of 15 second maximum voluntary ventilations (MVV.25) may be the test of choice for determining worker capability in wearing an industrial respirator.

Adolescent↗