The Circulation in Rest and Work on Mount Evans (4,300 M.)

Asmussen, Erik; Consolazio, F. C.

doi:10.1152/ajplegacy.1941.132.2.555

Cited by 38 publications

(7 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Although Asmussen and Consolazio 6 found the initial decrease in plasma volume on Mount Evans (4,300 m) to be accompanied by an increased cardiac output, their rebreathing method may have overestimated cardiac output at high altitude. 2 Klausen 2 considered that the early decrease in blood volume at high altitude played an important role in causing the decrease of cardiac output, because the only subject of three who failed to show a decrease in stroke volume at an altitude of 3,800 m also failed to show a decrease in blood volume.…”

Section: Discussionmentioning

confidence: 93%

Maintained stroke volume but impaired arterial oxygenation in man at high altitude with supplemental CO2.

Grover¹,

Reeves²,

Maher³

et al. 1976

Circulation Research

View full text Add to dashboard Cite

Hypobaric hypoxia causes hypocapina and alkalosis, hemoconcentration and increased hematocrit, and a decreased cardiac stroke volume. To assess the role of the hypocapnic alkalosis in causing these other changes, five men were exposed to hypobaric hypoxia at a barometric pressure (PB) of 440 torr with an alveolar O2 tension of 55 torr for 5 days with 3.77% CO2 added to the atmosphere to prevent alkalosis. They did not lose weight, and arterial CO2 tension, pH, and cardiac stroke volume were unchanged. An unchanged hematocrit implied an unchanged plasma volume. During exercise to maximum, stroke volumes equaled sea level values but arterial hypoxemia was profound, the arterial O2 tension being 39 torr. By contrast, three men at high altitude without CO2 supplementation (PB=455 torr; alveolar PO2=56 torr) had weight loss, hypocapnia, alkalosis, and decreased stroke volume. Increased hematocrits suggested decreased plasma volumes. During exercise, arterial PO2 (48 torr) was higher than in the group receiving CO2. Maximum oxygen uptakes were decreased to a similar degree in the two groups. Catecholamine excretion doubled in the group with CO2 but in the group without CO2 catechoamine excretion was unchanged. A normal pH at high altitude apparently maintained plasma volume, which, with the increased catecholamine excretion, may have prevented a decrease in stroke volume. However, the subjects with CO2 added did not have enhanced oxygen transport, because their arterial oxygenation was impaired.

show abstract

Section: Discussionmentioning

confidence: 93%

Maintained stroke volume but impaired arterial oxygenation in man at high altitude with supplemental CO2.

Grover¹,

Reeves²,

Maher³

et al. 1976

Circulation Research

View full text Add to dashboard Cite

show abstract

“…Like us, they observed major reductions in plasma volume during the first 2-4 months at altitude. Earlier observations by Asmussen & Consolazio (1941) on Mount Evans had suggested that plasma volume reduction is an early response to altitude and causes an increase in haemoglobin concentration of 10-15 % during the first few days at altitude, the continued rise in subsequent weeks being due to increased erythropoiesis.…”

Section: Discussionmentioning

confidence: 99%

Blood volume and haemoglobin concentration at altitudes above 18,000 ft. (5500 m)

Pugh¹

1964

The Journal of Physiology

109

View full text Add to dashboard Cite

The haemoglobin levels of climbers ascending to great altitudes in the Himalaya or the Karakoram do not as a rule reach the high values (22.9 + 2*6 g/100 ml.) reported on South American miners living at 17,500 ft. (5340 m;Dill, Talbott & Consolazio, 1937). Observations on sixty subjects on eight mountaineering expeditions (including the present one) showed a final mean haemoglobin value of 20-19 g/100 ml. (Table 1). On Mount Cho Oyu (1952) Pugh, unpublished). These results (as well as the small variation between expeditions) suggest that 20 + 1-5 g/100 ml. is a physiological limit for plainsmen living at heights above 18,000 ft. (5500 m). However, rather large variations have been observed occasionally in small groups after final assaults on high peaks. For example, Luft (1941) reported a mean value of 24 g/100 ml. on four subjects, while Somervell (1925) and Brendel (1956) noted falls in haemoglobin. The Himalayan Scientific and Mountaineering expedition of 1960/61 made a further contribution to the subject by measuring blood volume and haemotocrit changes as well as haemoglobin. This expedition spent 81 months above 15,000 ft. (4570 m), including 5 months at 19,000 ft. (5800 m), and was therefore in the field much longer than previous expeditions, most of which have lasted 3 months and none longer than 6 months. METHODSBlood volumes were estimated by a carbon monoxide method twice before leaving England and three times in the Himalaya. The procedure was as follows:The subjects rebreathed a gas mixture containing a known quantity of carbon monoxide. Venous blood samples were drawn without stasis before and after 10 min of rebreathing. The rebreathing system consisted of a mouthpiece, soda-lime container and 2-1. anaesthetic bag, to which oxygen could be added from another bag via a three-way tap. The other arm of the tap was connected to a calibrated chamber of either 150 or 250 ml. capacity, according to the altitude. This was similar to the absorption chamber of a Van Slyke manometric apparatus, and was fitted with a water jacket. Carbon monoxide of measured purity was drawn into this chamber over mercury and stored at known temperature,

show abstract

“…

INTRODUCTIONE XPOSURE TO HYPOXIA increases heart rate both at rest and during submaximal exercise (Asmussen and Consolazio, 1941). At near maximal and maximal workloads, however, there is a reduction in heart rate with increasing altitude and with time spent in altitude (Christensen and Forbes, 1937).

…”

mentioning

confidence: 99%

Peak Heart Rates at Extreme Altitudes

Lundby

Hall

2001

High Altitude Medicine & Biology

View full text Add to dashboard Cite

We have measured maximal heart rate during a graded maximal bicycle exercise test to exhaustion in five healthy climbers before and during an expedition to Mt. Everest. Maximal heart rates at sea level were 186 (177-204) beats/min(-1) at sea level and 170 (169-182) beats/min(-1) with acute hypoxia. After 1, 4 and 6 weeks of acclimatization to 5400 m, maximal heart rates were 155 (135-182), 158 (144-182), and 155 (140-183) beats/min(-1), respectively. Heart rates of two of the climbers were measured during their attempt to reach the summit of Mt. Everest without the use of supplemental oxygen. The peak heart rates at 8,750 m for the two climbers were 142 and 144 beats/min(-1), which were similar to their maximal heart rates during exhaustive bicycle exercise at 5,400 m, the values being 144 and 148 beats/min(-1), respectively. The peak heart rates at 8,750 m are in agreement with other field studies, but considerably higher than values reported from hypobaric chamber studies.

show abstract

The Circulation in Rest and Work on Mount Evans (4,300 M.)

Cited by 38 publications

References 0 publications

Maintained stroke volume but impaired arterial oxygenation in man at high altitude with supplemental CO2.

Maintained stroke volume but impaired arterial oxygenation in man at high altitude with supplemental CO2.

Blood volume and haemoglobin concentration at altitudes above 18,000 ft. (5500 m)

Peak Heart Rates at Extreme Altitudes

Contact Info

Product

Resources

About