Vergleichende Untersuchungen zur postoperativen Volumentherapie bei kardiochirurgischen Patienten

Zusammenfassung

Die Auswirkung einer hyperton-hyperonkotischen Lösung (HHL) auf kardiozirkulatorische Parameter wurden in dieser Studie an 21 hypovolämischen Patienten nach kardiochirurgischen Eingriffen mit den Effekten zweier isoton-isoonkotischer Lösungen (HA, HÄS) verglichen. Insbesondere wollten wir prüfen, ob durch Gabe der HHL (10% HÄS 200/0,5 in 7,2% NaCl) in Form einer „small-volume-resuscitation“ eine Kreislaufstabilisierung mit geringerer Volumenbelastung als durch Gabe von HA (5% Humanalbumin) bzw. HÄS (6% HÄS 200/0,5 in 0,9% NaCl) erreicht werden kann. Die Hypovolämie ließ sich mit HHL in wesentlich geringerer Dosierung (236±80 ml) ausgleichen als durch HA bzw. HÄS (857±244 ml, bzw. 1000±0 ml), wie aus dem Verlauf hämodynamischer Parameter (Herzindex, rechts- und linksventrikulärer Füllungsdruck) und der intravasalen Volumina (totales zirkulierendes Blutvolumen, intrathorakales Blutvolumen) hervorging. Diese größere Volumenwirksamkeit der HHL gegenüber HA und HÄS war jedoch nur ca. 2 h lang nachzuweisen. Über den gesamten Beobachtungszeitraum von 20 h ließ sich kein volumensparender Effekt der HHL feststellen. Für die akute Therapie einer hypovolämischen Kreislaufsituation stellt die HHL jedoch eine sichere und effektive Alternative zu anderen kolloidalen Volumenersatzmitteln dar.

Abstract

Patients who have undergone cardiac surgery with use of extracorporeal circulation frequently reveal marked hypovolaemia in spite of a highly positive fluid balance. This is thought to be due to transient microvascular damage and extravascular fluid shift. Further volume replacement to achieve haemodynamic stability in the postoperative period may cause fluid overload and congestive heart failure. The present study was designed to investigate whether this fluid overload could be avoided by using a hypertonic-hyperoncotic solution (group I: HHL, 10% hydroxyethylstarch 200/0.5 in 7.2% saline) instead of two different standard colloid solutions (group II: HA, 5% albumin; group III: HES, 6% hydroxyethylstarch in 0.9% saline).

Methods. Twenty-one patients meeting our criteria for hypovolaemia immediately after cardiac surgery were randomly assigned to three groups. Patients in group I received HHL in increments of 150 ml, while patients in group II and group III were given HA and HES respectively in increments of 500 ml until hypovolemia was corrected. Haemodynamic assessment was done using a pulmonary artery thermodilution catheter. Intra- and extravascular volumes, including extravascular lung water (EVLW), intrathoracic blood volume (ITBV), and total blood volume (TBV) were measured by the double indicator technique using lung water software (COLD-System, Pulsion, Munich, Germany).

Results. Correction of hypovolaemia-related haemodynamic parameters and restoration of normal TBV were achieved by 236±80 ml of HHL (group I), 857±244 ml of HA (group II) and 1000±0 ml of HES (group III) respectively. TBV increased significantly in each group, compared to baseline values. EVLW did not change significantly in any group. We found that the volume-augmenting effect of HHL per millilitre infused solution was more than four times that of HA and HES, primarily as a result of increasing plasma osmolality due to an increase of plasma sodium levels.

This pronounced effect on intravascular volume of HHL lasted for only 2 h following infusion, however, and did not lead to any unwanted side effects. In the period between 2 and 20 h after primary volume replacement, further fluid therapy with colloids and crystalloids, guided by clinical signs of hypovolaemia, was necessary in each group of patients. The overall fluid requirements for the first 20 h after operation did not differ among the three resuscitation regimens.

Conclusion. We found that HHL is a safe and effective solution for acute correction of hypovolaemia after cardiac surgery. The advantages of a smaller initial volume load by HHL cannot be maintained for longer than 2 h.