Biomedical subjects

J Coudert

Publications and source records attributed to J Coudert.

At least 91 records · Page 5Linked to original sources

PubMed1976

Pressure-flow-volume relationships in pulmonary circulation of normal highlanders.

Pulmonary vascular pressures and blood flow were measured with and without unilateral pulmonary arterial occlusion (UPAO) at rest and during exercise in 10 normal highlanders at La Paz, Bolivia (altitude, 3,750 m). In 6 other highlanders at rest and during exercise, pulmonary pressures, flow, and blood volume were measured during air breathing (PIO2 congruent to 100 Torr) and 29-30% oxygen (PIO2 congruent to 150 Torr). During air breathing, pulmonary vascular resistance was elevated at rest and did not change with exercise. Pulmonary arterial pressure rose less at rest with UPAO than during exercise without UPAO, and pulmonary vascular resistance was less in the former. Raising PaO2 to normal sea-level values had no effects on the pulmonary circulation at rest but prevented to a large extent the rise in pulmonary arterial pressure during exercise. Hence pulmonary vascular resistance during exercise was lower with oxygen than without. Thus, hypoxic vasoconstriction contributed to the pulmonary hypertension during exercise in normal highlanders. Circumstantial evidence suggests that this is related to the profound mixed venous hypoxemia caused by exercise in a hypoxic environment.

Adolescent↗

PubMed1975

Ccomparison of cisternal and lumbar cerebrospinal fluid pH in high altitude natives.

Samples of cisternal or lumbar cerebrospinal fluid were obtained from 20 young male volunteers born and living at high altitude (3500 to 4800 m). The pH, carbon dioxide and oxygen tensions, and bicarbonate concentration were measured and compared with those in the arterial and jugular venous blood. A consistent difference between the two CSF compartments was noted, particularly a lower pH (0.05), a higher PCO2 (7 Torr), and a lower PO2 (7 Torr) at the lumbar site. Mean bicarbonate concentration was not significantly different at the two sites. The main factor is PCO2, which controls the pH variation. These differences were more marked in high-altitude natives than in man at sea level. The existence of a consistent inhomogeneity of CSF acid-base content emphasizes the inaccuracy of using lumbar CSF pH to estimate the ECF pH as regulator of pulmonary ventilation and determinant of cerebral blood flow.

Acid-Base Equilibrium↗

PubMed1975

Regional distribution of pulmonary blood flow in normal high-altitude dwellers at 3,650 m (12,200 ft).

Simultaneous isotope dilution curves were recorded from the right upper (QRUZ) and right lower lung zones (QRLZ) by surface scanning in the sitting and recumbent positions in 15 normal high-altitude-born (HAD) males and in 1 HAD female as well as from 3 male newcomers, using 10 muCi of 131I-HSA as a bolus injection into the right ventricle. Similar information was also obtained at sea level from 5 normal males. The mean percent distribution of total pulmonary blood flow (Q) to RUZ and RLZ in the two body postures indicate (1) that in the vertical position RUZ in males receives about 17% of Q regardless of altitude and elevation in mean pulmonary artery pressure (MPAP) in HAD of 8.6 mm Hg above that extant at sea level; (2) recumbency at high altitude showed QRUZ also to be lower than at sea level; (3) elevation in MPAP at altitude has no significant effect on changing the sea-level distribution pattern of pulmonary blood flow.

Adolescent↗

PubMed1975