ISSN:
1432-2013
Keywords:
Acidosis
;
Alkalosis
;
Ideal alveolararterial O2 pressure difference
;
Physiological venous admixture
;
Oxyhemoglobin dissociation curve
Source:
Springer Online Journal Archives 1860-2000
Topics:
Medicine
Notes:
Abstract The effect of variation of blood hydrogen ion concentration on arterial and mixed venousP O 2,ideal alveolar-arterial O2 pressure difference (P AiO2−P aO2),venous admixture (Q s/Q t), arterio-alveolar CO2 pressure difference (a−A)D CO 2,physiological dead space to tidal volume ratio (V D/VT),cardiac output (Q t) and mean pulmonary arterial pressure ( $$\overline {{\text{PAP}}} $$ ) has been studied. Arterial and mixed venousP O 2increased and (P AiO2−P aO2)decreased with increasing blood hydrogen ion concentration. No change in (Q s/Q t), (a−A)-D CO 2,V D/VT,Q t and $$\overline {{\text{PAP}}} $$ was observed. The effect of hydrogen ion concentration on arterial and mixed venousP O 2and on (P AiO2−P aO2)is mainly due to a shift of the blood oxyhemoglobin dissociation curve (ODC), i.e. due to the Bohr effect. The upper part of the ODC is more flat in alkalosis (shift to the left) than in acidosis (shift to the right). Therefore the same end-capillary to arterial O2 content difference results in a greater (P AiO2−P aO2)in alkalosis than in acidosis. Any factor influencing the slope of the upper part of the ODC is expected to affect the arterialP O 2and the (P AiO2−P aO2)by this mechanism. Similarly any factor shifting the steep part of the ODC is expected to affect theP O 2of the mixed venous blood.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00582609
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