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Biomedical subjects

R H Secker-Walker

Publications and source records attributed to R H Secker-Walker.

8 recordsLinked to original sources
PubMed1979

Helium-oxygen flow volume curves in young healthy adults.

Helium-oxygen (HeO2) flow volume curves were done in young, healthy, nonsmoking adults. This paper discusses the theoretical design of the test, the nomenclature, and the results in this population. Our study shows that HeO2 and air curves crossed around 15% of vital capacity; one point of identical flow occurs more frequently than has been appreciated; and fully developed laminar flow occurs infrequently at low lung volumes in young adults.

Adult↗
PubMed1979

Observations on regional ventilation and perfusion in kyphoscoliosis.

Studies of regional ventilation and perfusion have been made in 10 patients with kyphoscoliosis. In 7 of the 10 patients ventilation was more severely impaired in the region of the maximum convexity than in the opposite lung. Perfusion was not impaired to the same degree. The resulting locally diminished ventilation-perfusion ratios may account for the hypoxemia and increased PA-aO2 gradient seen in patients with kyphoscoliosis. It is suggested that the local distortion of the chest wall, with the splayed out ribs, may account for the local change in lung mechanics.

Adolescent↗
PubMed1976

Estimating relative renal function.

Radionuclide measurements of relative renal function have been made using conventional dual-probe renography, computer assisted triple-probe renography, rectilinear kidney scanning and computer assisted gamma camera renography and kidney scanning. The relative area of each kidney from the excretory urogram also has been used to measure relative function. The best correlation between renography and kidney scanning was obtained with the gamma camera computer system. The relative function of each kidney was obtained by outlining regions of interest that corresponded closely to the renal images and subtracting the blood and tissue background activity, using a special background region. Triple-probe renography, using computer assisted blood background subtraction, provides another reliable indicator of relative function, which is considerably more accurate than conventional dual-probe renography. Relative renal function also may be determined, but with less precision, from the relative counts in a rectilinear kidney scan, from the relative scan areas and from the relative areas found on excretory urography. Both relative area methods are less reliable in the presence of outflow tract obstruction, renal tumors and renal cysts.

Aged↗
PubMed1975

Regional ventilation-perfusion relationships.

Regional ventilation-perfusion ratios have been determined in 12 healthy subjects, 16 patients with pulmonary embolism, and 22 patients with chronic obstructive lung disease. The ventilation-perfusion ratios were determined from xenon-133 ventilation studies and 99-tc-m-labeled particle perfusion scans, using either the fractional exchange of air or the relative distribution of tidal volume per unit volume as the numerator of the ratio. A comparison of these two methods showed comparable distributions of regional ventilation-perfusion relationships in the healthy subjects and patients with pulmonary embolism. However, in the patients with chronic obstructive pulmonary disease, the fractional exchange method clearly separated this group of patients from the others.

Chemotherapy, Cancer, Regional Perfusion↗
PubMed1975

The measurement of regional ventilation during tidal breathing: a comparison of two methods in healthy subjects, and patients with chronic obstructive lung disease.

Regional ventilation has been measured in 17 healthy volunteers, and 24 patients with chronic obstructive lung disease during tidal breathing using 133-Xe. The wash-in and wash-out of 133-Xe were recorded by a gamma camera interfaced to a small digital computer. Regional ventilation was calculated as the distribution of tidal volume per unit lung volume-a measure of relative ventilation--and from the wash-out curves as the fractional exchange of air per second. Determination of the regional fractional exchange of air showed a significant difference between the patients with chronic obstructive lung disease and normal subjects for all regions. The distribution of tidal volume per unit lung volume did not effect such a clear separation. Significant correlations were found between the whole-lung fractional exchange of air in the patients with chronic obstructive lung disease and their FEV1 r equal 0-70, MMFR r equal 0-70, FVC r equal 0-56 and FEV1/FVC r equal 0-57. It is suggested that measurement of regional ventilation as the fractional exchange of air is more realistic than methods that determine relative ventilation or only make use of the early part of the wash-out 133-Xe.

Adult↗