Increasing cardiac output by fluid loading: effects on indocyanine green plasma disappearance rate and splanchnic microcirculation.
BACKGROUND
Sufficient cardiac pre-load for maintaining adequate cardiac output is a major goal in the treatment of critically ill patients. We studied the effects of increasing cardiac output by fluid loading on the indocyanine green plasma disappearance rate (ICG-PDR) and gastric mucosal regional CO2 tension (PRco2) as an indicator of splanchnic microcirculation.


METHODS
With approval by our ethics committee and written consent, we studied post-operatively 12 patients (1 female, 11 males; 66 +/- 13 years) with elective coronary artery bypass grafting (n = 10) or aortic valve replacement (n = 2). All patients had received pulmonary artery and left atrial catheterization previously for clinical indications. Cardiac output and filling pressures were measured immediately after intensive care unit (ICU) admission and 1 h after the beginning of fluid loading.


RESULTS
Overall, 630 +/- 130 ml of 6% hydroxyethylstarch (130 kDa) was infused with the splanchnic perfusion pressure remaining constant. Norepinephrine and epinephrine dosages were unchanged. The cardiac index increased significantly from 2.8 +/- 0.7 to 3.5 +/- 0.6 l/min/m2 and the stroke volume index from 30 +/- 7 to 38 +/- 8 ml/m2. ICG-PDR showed no significant change, i.e. from 21.2 +/- 6.5 to 21.6 +/- 6.5%/min. Gastric mucosal PRco2 and the Pco2 gap (difference between regional and end-tidal CO2 tension) were constant, i.e. changed from 5.1 +/- 0.8 to 5.5 +/- 1.1 kPa and from 0.9 +/- 0.5 to 1.0 +/- 0.7 kPa, respectively.


CONCLUSIONS
Increasing cardiac output to supranormal values by fluid loading is not associated with a significant change in ICG-PDR or gastric mucosal PRco2.
Hofmann
D
D
Department of Anesthesiology and Intensive Care Medicine, Friedrich-Schiller-University of Jena, Jena, Germany.
Thuemer
O
O
Schelenz
C
C
van Hout
N
N
Sakka
S G
SG
D018806:APACHE; D000368:Aged; D000369:Aged, 80 and over; D002245:Carbon Dioxide / Q000097:blood; D002302:Cardiac Output / Q000502:physiology*; D002315:Cardiopulmonary Bypass; D004396:Coloring Agents; D004837:Epinephrine / Q000097:blood; D005260:Female; D019918:Heart Valve Prosthesis Implantation; D006801:Humans; D006895:Hydroxyethyl Starch Derivatives / Q000494:pharmacology; D007208:Indocyanine Green; D008111:Liver Function Tests; D008297:Male; D008833:Microcirculation / Q000502:physiology*; D008875:Middle Aged; D009638:Norepinephrine / Q000097:blood; D010952:Plasma Substitutes / Q000494:pharmacology; D012121:Respiration, Artificial; D013152:Splanchnic Circulation / Q000502:physiology*
D004396:Coloring Agents; D006895:Hydroxyethyl Starch Derivatives; D010952:Plasma Substitutes; D002245:Carbon Dioxide; D007208:Indocyanine Green; D009638:Norepinephrine; D004837:Epinephrine