Changes in the Rheologic Properties of Blood after a High Altitude Expedition

Abstract

The changes in blood rheologic properties induced by exposure to high altitude plus heavy and prolonged physical strain were investigated in 14 climbers of an Italian expedition to Himalaya (maximum altitude reached m 7350). In blood samples collected immediately after return, alterations of some haemorheologic parameters were observed in comparison with baseline values, and namely an increase in relative blood viscosity, fibrinogen and erythrocyte filtration time along with a fall in platelet count. Treatment with a drug acting on the red cell deformability (Pentoxifylline) appeared to prevent the changes in blood viscosity and erythrocyte filterability. In the 9 climbers whom we were able to re-examine after three months, all altered parameters were found to be restored to baseline values. These results contribute to the knowledge of the pathogenesis of high altitude disease and stress the significance of altered haemorheology as one of the mechanisms possibly involved in the vascular events observed in this condition.

Acetazolamide and chronic hypoxia: effects on haemorheology and pulmonary haemodynamics

“…The increase in PVR induced by chronic hypoxia might be due to several factors, such as blood rheological changes [10], hypoxic vasoconstriction or the muscularisation of pulmonary vasculature [2,8]. Our data do not support a role of aggregation and deformability of RBCs in the increase in PVR under hypoxia.…”

“…However, no data are currently available regarding the effects of acetazolamide on blood viscosity. The changes in PVR observed in chronic hypoxia could be related to several mechanisms, such as pulmonary vascular remodelling [2,8], haemorheological changes [9,10], hypoxic vasoconstriction [11] or greater nitric oxide scavenging by erythrocytes as a consequence of the rise of Hct [12]. Polycythaemia in various models (mice, rats and guinea pigs) appears to be involved in pulmonary hypertension by increasing blood viscosity [13].…”

“…Blood viscosity depends on Hct but also on the ability of [14]. These latter haemorheological factors may considerably modulate blood flow resistance at the lung level [14][15][16] and can be influenced by chronic hypoxic exposure [10,17].…”

Effects of Demographic Characteristics, Health-Related Behaviors and Lifestyle Factors on the Prevalence of Hypertension for the Middle-Aged and Elderly in the Guangxi Hei Yi Zhuang and Han Populations

“…(1) The vast majority of the Hei Yi Zhuang people live in mountainous areas at an altitude of 900-1,600 m, with a relative altitude of 200-500 m. It has been found that as the altitude increases gradually, the reference value of whole-blood contrast viscosity also increases gradually [27,28] . A recent study has shown that chronic hypoxia causes marked activation of the sympathetic nervous system in healthy humans and increased systemic arterial pressure [29] , the secretion of catecholamine [29,30] , vasopressin [31,32] , and adrenocorticotropin [33,34] was also increased, and may promote the development of hypertension by the renin-angiotensin-aldosterone system [35,36] .…”

The Role of Hypoxia and Platelets in Air Travel-Related Venous Thromboembolism

“…In humans, altitude has been reported to either increase [59][60][61] or decrease [62,63] platelet count and platelet aggregation has been reported to be decreased [64] or to be either increased, decreased or normal, depending on the measurement technique used [65]. In chronic respiratory disease, platelet survival time has been reported to be reduced [66], platelet volume to be increased [67] or not affected [68], platelet count to be unaffected [68] and platelet aggregation to be increased [69,70].…”