[Acute perioperative hemodilution without using hydroxyethyl starch : hemodynamic alterations under "controlled" hypovolemia].
BACKGROUND
Up to now hydroxyethyl starch preparations have frequently been used to compensate for volume deficits accompanying blood withdrawal during acute normovolemic hemodilution. This approach was questioned with respect to the current limitations for use of hydroxyethyl starch solutions imposed by the European Medicines Agency. Because crystalloids distribute evenly across the whole extracellular compartment, 80 % of the infused solution will be "lost" to the interstitial space. Thus, a physiological adjustment of blood loss caused by hemodilution with crystalloids alone (1:5 ratio) seems hardly feasible and according to current data perhaps not even desirable. A 3:1 ratio (crystalloids versus blood loss) as applied in the current study can be regarded as a practical compromise between physiological needs and recommendations according to the literature (1.4:1) but will lead to moderate hypovolemia the hemodynamic consequences of which are not well described.


OBJECTIVE
The current study investigates the hemodynamic impact of a hemodilution with crystalloids under the precondition of a 3:1 substitution ratio compared to withdrawn blood.


METHODS
In the context of acute perioperative hemodilution 10 otherwise healthy women graded I and II on the American Society of Anesthesiologists (ASA) classification scheduled for open gynecological cancer surgery underwent an average blood withdrawal of 1097 ± 285 ml which was substituted by an average of 3430 ± 806 ml of Ringer's lactate. The resulting deficit in blood volume was exactly quantified by a double tracer technique. Hemodynamic changes were evaluated by a combination of thermodilution and pulse contour analysis (PiCCO system®). Subsequently, the remaining volume deficit was compensated by 245 ± 64 ml of a 20 % albumin solution and hemodynamic parameters were again evaluated.


RESULTS
When infusing Ringer's lactate in a 3:1 ratio compared to the actual blood loss, the blood volume decreased by 12 %. The volume effect of Ringer's lactate proved to be 17 %. While mean arterial pressure and heart rate remained constant, key hemodynamic parameters changed relevantly during the time course. A significant rise in cardiac output and myocardial contractility could be observed which was accompanied by a decrease in systemic vascular resistance. In contrast, cardiac preload and the parameters representing pulmonary vascular permeability remained unaltered. The infusion of 245 ± 64 ml of a 20 % albumin solution nearly completely restituted blood volume and led to an insignificant rise in systemic vascular resistance but did not normalize cardiac output or myocardial contractility.


CONCLUSIONS
In the study population, the loss of intravascular fluid during perioperative haemodilution could be compensated by an increase in cardiac performance. However, whether patients with a reduced cardiac capacity (i.e. older patients) are capable to improve their cardiac output sufficiently in order to compensate hypovolemia accompanying perioperative haemodilution with crystalloids remains questionable.
Klinik für Anaesthesiologie, Klinikum der Universität München, München, Deutschland, Klaus.Hofmann-Kiefer@med.uni-muenchen.de.
K
K
Hofmann-Kiefer
D
D
Chappell
M
M
Jacob
A
A
Schülke
T
T
Helfen
J
J
Anetzberger
M
M
Rehm
D000328:Adult; D000368:Aged; D001794:Blood Pressure / Q000187:drug effects; D002302:Cardiac Output / Q000187:drug effects; D000077324:Crystalloid Solutions; D005260:Female; D013509:Gynecologic Surgical Procedures; D006438:Hemodilution / Q000379:methods*; D006439:Hemodynamics / Q000187:drug effects*; D006801:Humans; D006895:Hydroxyethyl Starch Derivatives / Q000009:adverse effects*; D020896:Hypovolemia / Q000503:physiopathology*; D007552:Isotonic Solutions / Q000627:therapeutic use*; D008297:Male; D008875:Middle Aged; D010952:Plasma Substitutes / Q000627:therapeutic use*; D011182:Postoperative Care; D000077325:Ringer's Lactate
D000077324:Crystalloid Solutions; D006895:Hydroxyethyl Starch Derivatives; D007552:Isotonic Solutions; D010952:Plasma Substitutes; D000077325:Ringer's Lactate