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Biomedical subjects

R Gilbert

Publications and source records attributed to R Gilbert.

At least 163 records · Page 9Linked to original sources

Prospective study of controlled oxygen therapy. Poor prognosis of patients with asynchronous breathing.

Thirty-two patients were evaluated within 24 hours of admission for 36 episodes of acute respiratory failure (arterial oxygen pressure less than or equal to 50 mm Hg). Clinical data, spirometric determinations, blood gas analysis, and synchronization of chest (rib cage) and abdominal (diaphragmatic) breathing movements were studied. All patients were initially treated with controlled oxygen therapy. In 25 episodes the patients recovered without intubation (successes). In nine episodes the patients required intubation and assisted ventilation; two of these patients died. Two patients died without intubation. The 25 successful episodes were compared with the 11 requiring intubation or associated with death (failures). The breathing pattern proved to be the best single factor for predicting success or failure (77 percent correct prediction). The breathing pattern plus the arterial carbon dioxide tension on admission was the best two-factor guide (86 percent correct prediction). Patients with asynchronous breathing and severe hypercapnia are so unlikely to do well with a program of controlled oxygen therapy that preparations for intubation and assisted ventilation should be made on admission and such measures should be instituted at the first sign of deterioration.

Airway Obstruction↗

Effect of cardiac, pulmonary, and vascular disease on one-minute oxygen uptake.

A simplified method for estimation of one-minute oxygen uptake (VO2-1) during treadmill grade walking at vertical power requirements of 250, 750, and 1,000 kg-meters/min was devised, where power=weight (kg) X grade (fractional) X walking speed. All subjects were men. There were 29 controls, 34 subjects with coronary arterial disease (of whom 18 had had myocardial infarction), nine subjects with diffuse pulmonary disease, and four subjects with ischemic vascular disease. Abnormally reduced values for VO2-1 were related to these diseases and, more specifically, to a history of myocardial infarction and (in pulmonary subjects) to reduced single-breath diffusing capacity. Lowest values of VO2-1 for a group were found in ischemic vascular disease. Reduced response of VO2-1 may therefore be caused by central defects of oxygen transport.

Adult↗

Nonshivering thermogenesis and cold resistance in rats under severe cold conditions.

Following either chronic exposure to 6 degrees C, or outdoor winter exposure, or chronic treatment with tyramine rats were exposed to -40 degrees C and their oxygen consumption and colonic temperature monitored. Fall in body temperature with time of exposure followed a sigmoid curve which had an inflection point around 32.9 degrees C. Both the time required for body temperature to reach this point and hypothermic resistance defined as the total O2 consumed up to the inflection time were useful indices of resistance to severe cold; Three days before the cold tests, capacity for norepinephrine-induced nonshivering thermogenesis was measured in all animals by examination of their metabolic response to tyraminemthe magnitude of response to tyramine correlated well with hypothermic resistance only for those rats chroncally treated with tyramine. It is concluded that it is impossible to predict with any reasonable degree of confidence the cold resistance of a rat from its tyramine response. In cold-acclimated rats, factors in addition to norepinephrine sensitivity are significantly involved in cold resistance and deserve further studies.

Acclimatization↗

Asynchronous breathing movements in patients with chronic obstructive pulmonary disease.

An electromagnetic ventilation monitor was used to record the separate anterior-posterior movements of the chest and abdomen during the breathing cycle in 30 patients with chronic obstructive pulmonary disease (COPD) and in 10 normal subjects. In all normal subjects and 17 COPD patients, the chest and abdomen movements were syndhronous and in phase with the flow of air as measured with a spirometer. In 13 COPD patients chest movement was synchronous with the flow of air, but the abdomen moved inward suddently near or at end inspiration and then outward during a variable part of expiration. Compared to COPD patients with a normal breathing pattern, those with asynchronous breathing movements had poorer ventilatory mechanics and 10 of the 13 were dependent on assisted ventilation. Nine of the 13 patients with asynchronous breathing have died in a 10 month period, a significantly higher mortality than in those with normal breathing.

Abdomen↗