Premium
Venous oxygen saturation during normovolaemic haemodilution in the pig
Author(s) -
Krantz T.,
Warberg J.,
Secher N. H.
Publication year - 2005
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.1399-6576.2005.00778.x
Subject(s) - hydroxyethyl starch , cardiac output , medicine , anesthesia , blood volume , central venous pressure , oxygen , hemodynamics , cardiology , heart rate , blood pressure , chemistry , organic chemistry
Background: Hypovolaemia may be considered to represent a volume‐restricted cardiac output (CO), but CO varies inversely with the haemoglobin concentration (Hb) and a maximal mixed venous oxygen saturation (S v O 2 ) may be a better target for volume administration than a maximal CO. Methods: In 10 anaesthetized pigs, volume loading with 6% hydroxyethyl starch was performed to obtain a maximal S v O 2 followed by normovolaemic haemodilution with 6% hydroxyethyl starch. Results: Volume loading increased S v O 2 from 55.0 ± 5.2% to 64.8 ± 9.0% (mean ± SD) associated with an increase in CO (2.3 ± 0.4 to 3.5 ± 0.9 l/min) and central venous oxygen saturation (S cv O 2 ; 68.2 ± 9.3% to 79.4 ± 7.2%; P < 0.05). Heart rate (HR), mean arterial (MAP), central venous (CVP), pulmonary arterial mean (PAMP), and occlusion pressures (PAOP) increased as well ( P < 0.05). In contrast, during progressive haemodilution, S v O 2 and S cv O 2 remained statistically unchanged until the haemoglobin concentration had decreased from 5.5 ± 0.4 to 2.9 ± 0.2 mM, while CO and HR increased at a haemoglobin value of 4.4 ± 0.4 and 4.0 ± 0.4 mM and CVP and PAOP decreased at a haemoglobin of 4.0 ± 0.4 and 2.9 ± 0.2 mM, respectively ( P < 0.05) leaving MAP unaffected. Conclusion: This study found that volume loading increased cardiac output and mixed and central venous oxygen saturations in parallel, but during normovolaemic haemodilution an increase in cardiac output left mixed and central venous oxygen saturations statistically unchanged until haemoglobin concentration was reduced by ∼50%. Accordingly, volume therapy should be directed to maintain a high venous oxygen saturation rather than a change in cardiac output.