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Classes of tissue hypoxia
Author(s) -
SlGGAARDANDERSEN O.,
ULRICH A.,
GTHGEN I. H.
Publication year - 1995
Publication title -
acta anaesthesiologica scandinavica
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.738
H-Index - 107
eISSN - 1399-6576
pISSN - 0001-5172
DOI - 10.1111/j.1399-6576.1995.tb04348.x
Subject(s) - hypoxia (environmental) , oxygen , medicine , oxygen tension , endocrinology , anesthesia , chemistry , organic chemistry
We identify eight causes of tissue hypoxia, falling into three classes, A, B, and C, depending upon the effect on the critical mixed venous p O 2 and the optimal oxygen consumption rate. The critical mixed venous p O 2 is the value above which the oxygen consumption rate is optimal and independent of the mixed venous p O 2 and below which the oxygen consumption rate decreases towards zero. Class A hypoxia: primary decrease in mixed venous p O 2 . Causes: 1) ischaemic hypoxia (decrease in cardiac output), 2) low‐extractivity hypoxia (decrease in oxygen extraction tension, p 8 ). Class B hypoxia: primary increase in critical mixed venous p O 2 . Causes: 1) shunt hypoxia (increased a‐v shunting), 2) dysperfusion hypoxia (increased diffusion length from erythrocytes to mitochondria and/or decreased total capillary endothelial diffusion area, e. g., tissue oedema, microembolism), 3) histotoxic hypoxia (inhibition of the cytochrome chain). Class C hypoxia: primary increase in optimal oxygen consumption rate. Causes: 1) uncoupling hypoxia (uncoupling of the ATP formation associated with O 2 reduction), 2) hypermetabolic hypoxia (increased energy metabolism, e. g., due to hyperthermia).