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Biomedical subjects

R A Gabel

Publications and source records attributed to R A Gabel.

50 records · Page 3Linked to original sources
PubMed1976

Alkaline shift in lumbar and intracranial CSF in man after 5 days at high altitude.

In six healthy male volunteers at sea level (PB 747-759 Torr), we measured pH and PCO2 in cerebrospinal fluid (CSF), and in arterial and jugular bulb blood; from these data we estimated PCO2 (12) and pH for the intracranial portion of CSF. The measurements were repeated after 5 days in a hypobaric chamber (PB 447 Torr). Both lumbar and intracranial CSF were significantly more alkaline at simulated altitude than at sea level. Decrease in [HCO3-] IN lumbar CSF at altitude was similar to that in blood plasma. Both at sea level and at high altitude, PCO2 measured in the lumbar CSF was higher than that estimated for the intracranial CSF. At altitude, hyperoxia, in comparison with breathing room air, resulted in an increase in intracranial PCO2, and a decrease in the estimated pH in intracranial CSF. With hyperoxia at altitude, alveolar ventilation was significantly higher than during sea-level hyperoxia or normoxia, confirming that a degree of acclimatization had occurred. Changes in cerebral arteriovenous differences in CO2, measured in three subjects, suggest that cerebral blood flow may have been elevated after 5 days at altitude.

Acid-Base Equilibrium↗
PubMed1975

Hydrochloric acid in the correction of metabolic alkalosis.

Intravenous infusion of hydrochloric acid was used as a safe, effective, and quantitative method for correction of metabolic alkalosis in two patients. The first shows the risks of intravenously administered ammonium chloride, the currently available alternative to hydrochloric acid therapy. The second shows the efficacy of intravenously administered hydrochloric acid. While breathing spontaneously throughout the period of severe alkalosis, this patient showed compensatory hypoventilation with conspicuous increase in arterial carbon dioxide pressure. Normal spontaneous ventilation returned with correction of the metabolic alkalosis.

Aged↗
PubMed1975

Normal chemoreceptor function in obesity before and after ileal bypass surgery to force weight reduction.

Ventilatory responses to progressive isocapnic hypoxia and rebreathing of carbon dioxide in oxygen were determined in four obese women before and approximately 1 year after ileal bypass surgery to force weight reduction. None of the patients was hypoventilating and all had normal pulmonary function tests. The ventilatory responses to hypoxia were normal before surgery and were not effected by weight reduction. The ventilatory responses to hypercapnia did not change in slope but a shift of the carbon dioxide response line toward a lower arterial carbon dioxide tension occurred in two subjects after weight reduction. We conclude that obesity per se does not necessarily cause loss of hypoxic ventilatory drive.

Adult↗
PubMed1975

Ventilatory interaction between hypoxia and [H+] at chemoreceptors of man.

By measuring ventilation during isocapnic progressive hypoxia, peripheral chemoreceptor sensitivity to acute hypoxia (deltaV40) was measured in five normal young men under four sets of conditions: 1) at sea level at the subject's resting PCO2, 2) at sea level with PCO2 5 Torr above resting PCO2, 3) after 24 h at a simulated altitude of 4,267 m (PB = 447 Torr) at the subject's resting PCO2 measured during acute hyperoxia, and 4) after 24 h at high altitude, with PCO2 elevated to the subject's sea-level resting PCO2. With this experimental design, we were able to systematically vary the PCO2 and [H+] at the peripheral and central chemoreceptors of man. When mean pHa was decreased from 7.424 to 7.377 without significant change in PACO2, the mean deltaV40 increased from 18.0 to 55.9 1/min. Conversely, when mean PACO2 was altered between 33.8 and 41.6 Torr with pHa held relatively constant, the mean deltaV40 did not change. This suggests that it is the H+ and not CO2 which interacts with hypoxia in stimulating the ventilation of man. An additional finding was that the intrinsic sensitivity of the peripheral chemoreceptors to acute hypoxia did not change during 24 h of acclimatization to high altitude.

Adult↗
PubMed1975

Depression of ventilation hypoxia in man.

In five normal male subjects, ventilation, PaO2, and PaCO2 were measured during the rapid progressive isocapnic production of hypoxia (5 min) and during the equally rapid isocapnic reversal of hypoxia. At similar PaO2, PaCO2, and pH, ventilation was less at a time when alveolar PO2 was increasing than when alveolar PO2 was decreasing. We interpret these results as showing that human ventilation is depressed by mild-to-moderate hypoxia (40-60 Torr), that such depression is probably central, and that it is ordinarily masked by peripheral chemoreceptor stimulation. We are not able to distinguish whether the ventilatory depression is caused by decreased central chemoreceptor PCO2 due to an increase in cerebral flow, direct hypoxic depressing of the central respiratory mechanism, or both.

Adult↗