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211 results on '"ROBERTSON, H. THOMAS"'

1. Glossary of Terms

Author

Luks, Andrew M., Glenny, Robb W., Robertson, H. Thomas, Luks, Andrew M., Glenny, Robb W., and Robertson, H. Thomas

Published
2013
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3. Self-Assessment Cases

Author

Luks, Andrew M., Glenny, Robb W., Robertson, H. Thomas, Luks, Andrew M., Glenny, Robb W., and Robertson, H. Thomas

Published
2013
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43. Characteristics of peak aerobic capacity in symptomatic and asymptomatic subjects with left ventricular dysfunction

Author

Liang, Chang-seng, Stewart, Douglas K., LeJemtel, Thierry H., Kirlin, Philip C., McIntyre, Kevin M., Robertson, H. Thomas, Brown, Robert, Moore, Andrea W., Wellington, Karen L., Cahill, Linda, Galvao, Marie, Woods, Patricia A., Garces, Carlos, and Held, Peter

Subjects
Aerobic exercises -- Physiological aspects, Heart ventricle, Left -- Physiological aspects, Exercise tests, Blood gases -- Analysis, Health
Abstract

Expired gas analysis was used to determine the aerobic exercise performance of subjects with depressed left ventricular (LV) systolic function and congestive heart failure (CHF). To determine whether subjects with no or minimal CHF have better aerobic exercise performance than do those with overt CHF, oxygen consumption (V[O.sub.2]) at anaerobic threshold (AT) and peak exercise was measured in 184 subjects with LV ejection fraction [is less than or equal to] 0.35 who participated in the Studies of Left Ventricular Dysfunction. Subjects were divided into those with overt CHF needing treatment (treatment trial; n = 20) and those who had neither overt CHF nor treatment for CHF (prevention trial; n = 164). Treatment trial subjects had a lower LV ejection fraction (0.25 [+ or -] 0.07) than did prevention trial ones (0.29 [+ or -] 0.05; p = 0.001), but there were no differences in age, gender, body weight, resting heart rate and blood pressure. Treadmill exercise testing was performed after 2 to 3 weeks of placebo (no angiotensin-converting enzyme inhibitor) treatment. Treatment trial subjects exercised for a shorter time (493 [+ or -] 160 seconds) and attained a lower peak V[O.sub.2] (13 [+ or -] 4 ml/kg/min) and V[O.sub.2] at AT (11 [+ or -] 4 ml/kg/min) than did prevention trial ones (842 [+ or -] 277 seconds, and 20 [+ or -] 6 and 16 [+ or -] 5 ml/kg/min, respectively). Analysis of covariance showed that the the differences in peak [VO.sub.2] and V[O.sub.2] at AT were statistically significant between the 2 trials after adjusting for age, gender, LV ejection fraction and New York Heart Association functional class. In contrast, there was no correlation between the expired gas measurements and LV ejection fraction or New York Heart Association classification after adjusting for other factors. Thus, it is concluded that of subjects with reduced LV ejection fraction, those with no or minimal CHF have higher aerobic exercise performance than do those with overt CHF, and this difference cannot be explained by gender, age, LV ejection fraction or New York Heart Association functional class. (Am J Cardiol 1992;69:1207-1211)

Published
1992

46. Sporadic coordinated shifts of regional ventilation and perfusion in juvenile pigs with normal gas exchange

Author

Robertson, H Thomas, Neradilek, Blazej, Polissar, Nayak L, and Glenny, Robb W

Subjects
Aging, Pulmonary Circulation, Time Factors, Pulmonary Gas Exchange, Swine, Models, Biological, Microspheres, Fractals, Spectrometry, Fluorescence, Administration, Inhalation, Injections, Intravenous, Respiratory, Animals, Pulmonary Ventilation, Lung, Fluorescent Dyes
Abstract

Repeated high-resolution measurements of both regional pulmonary ventilation (rV˙A) and regional blood flow (rQ˙) have revealed that ∼6 to 10% of the summed spatial and temporal heterogeneity can be attributed to spontaneous temporal variability. To test the hypothesis that the spontaneous temporal shifts of rV˙ and rQ˙ are coordinated, 12 anaesthetized juvenile pigs had pairs of colours of aerosol and intravenous fluorescent microspheres (FMS) administered simultaneously at 20 min intervals to mark rV˙ and rQ˙. The animals were killed, the lungs inflated, air-dried and cut into ∼2 cm3 cubes. The concentrations of FMS colours from each cube, representing rV˙ and rQ˙ at every 20 min interval, were measured with a fluorescence spectrophotometer. The correlation between per-piece temporal shifts in rV˙ and rQ˙, calculated as the mean within-piece covariance, was positive (P < 0.001) for every temporally adjacent pair of measurements in every animal, although there were large differences in the magnitude of the mean temporal covariance among animals. The individual cubes with the most positive temporal covariance across all measurement periods usually demonstrated a large single-interval coordinated shift of rV˙ and rQ˙, with average temporal covariance observed at the other intervals. The largest between-interval shifts in rV˙A and rQ˙ included equal proportions of coordinated increases and coordinated decreases. High-resolution measurements of rV˙ and rQ˙ acquired over 20 min intervals reveal that the overall positive correlation between temporal changes in rV˙A and rQ˙ is driven by relatively infrequent large-magnitude changes within small regions of the lung.

Published
2007

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