Heinz Brechtelsbauer

Changes in blood volume and hematocrit during acute preoperative volume loading with 5% albumin or 6% hetastarch solutions in patients before radical hysterectomy.

BackgroundThe impact of acute preoperative volume loading with colloids on blood volume has not been investigated sufficiently. MethodsBefore surgery, in 20 patients undergoing major gynecologic procedures, volume loading was performed during anesthesia by infusing approximately 20 ml/kg of colloid at a rate of 90 ml/min (group I: 5% albumin solution; group II: 6% hetastarch solution; n = 10 each). Plasma volume (indocyanine green dilution technique), erythrocyte volume (labeling erythrocytes with fluorescein), hematocrit, total protein, and hetastarch plasma concentrations (group II) were measured before and 30 min after the end of infusion. ResultsMore than 1,350 ml of colloid (approximately 50% of the baseline plasma volume) were infused within 15 min. Thirty minutes after the infusion had been completed, blood volume was only 524 ± 328 ml (group I) and 603 ± 314 ml (group II) higher than before volume loading. The large vessel hematocrit (measured by centrifugation) dropped more than the whole body hematocrit, which was derived from double-label measurements of blood volume. ConclusionsThe double-label measurements of blood volume performed showed that 30 min after the infusion of approximately 20 ml/kg of 5% albumin or 6% hetastarch solution (within 15 min), only mean 38 ± 21% and 43 ± 26%, respectively, of the volume applied remained in the intravascular space. Different, i.e., earlier or later, measuring points, different infusion volumes, infusion rates, plasma substitutes, or possibly different tracers for plasma volume measurement might lead to different results concerning the kinetics of fluid or colloid extravasation.

Changes in intravascular volume during acute normovolemic hemodilution and intraoperative retransfusion in patients with radical hysterectomy.

Background: Changes in blood volume during acute normovolemic hemodilution (ANH) and their consequences for the perioperative period have not been investigated sufficiently. Methods: In 15 patients undergoing radical hysterectomy, preoperative ANH to a hematocrit of 24% was performed using 5% albumin solution. Intraoperatively, saline 0.9% solution was used for volume substitution, and intraoperative retransfusion was started at a hematocrit of 20%. Plasma volume (indocyanine green dilution technique), hematocrit, and plasma protein concentration were measured before and after ANH, before retransfusion, and postoperatively. Red cell volume (labeling erythrocytes with fluorescein) was determined before and after ANH and postoperatively. Results: Mean normal plasma volumes (1,514 ± 143 ml/m2) and reduced red cell volumes (707 ± 79 ml/m2) were measured preoperatively. Blood (1,150 ± 196 ml) was removed and replaced with 1,333 ± 204 ml of colloid. Blood volume before and after ANH was equal and amounted to 3,740 ml. Intraoperatively, plasma volume did not increase until retransfusion despite infusing 3,389 ± 1,021 ml of crystalloid (corrected for urine output) to compensate for an estimated surgical blood loss of 727 ± 726 ml. Postoperatively, after retransfusion of all autologous blood, blood volume was 255 ± 424 ml higher than preoperatively before ANH. Despite mean calculated blood loss of 1,256 ± 892 ml, only one patient received allogeneic blood. Conclusions: During ANH, normovolemia was exactly maintained. After surgical blood loss of 1,256 ± 892 ml, crystalloid and colloid supplies of 5,752 ± 1,462 ml and 1,667 ± 548 ml, respectively, and complete intraoperative retransfusions of autologous blood in every patient, mean blood volume was 250 ml higher than preoperatively before ANH.

Acid-base changes caused by 5% albumin versus 6% hydroxyethyl starch solution in patients undergoing acute normovolemic hemodilution: a randomized prospective study.

BackgroundPreoperative acute normovolemic hemodilution (ANH) is an excellent model for evaluating the effects of different colloid solutions that are free of bicarbonate but have large chloride concentrations on acid–base equilibrium. MethodsIn 20 patients undergoing gynecologic surgery, ANH to a hematocrit of 22% was performed. Two groups of 10 patients each were randomly assigned to receive either 5% albumin or 6% hydroxyethyl starch solutions containing chloride concentrations of 150 and 154 mm, respectively, during ANH. Blood volume (double label measurement of plasma and red cell volumes), pH, Paco2, and serum concentrations of sodium, potassium, chloride, lactate, ionized calcium, phosphate, albumin, and total protein were measured before and 20 min after completion of ANH. Strong ion difference was calculated as serum sodium plus serum potassium minus serum chloride minus serum lactate. The amount of weak plasma acid was calculated using a computer program. ResultsAfter ANH, blood volume was well maintained in both groups. ANH caused slight metabolic acidosis with hyperchloremia and a concomitant decrease in strong ion difference. Plasma albumin concentration decreased after hemodilution with 6% hydroxyethyl starch solution and increased after hemodilution with 5% albumin solution. Despite a three-times larger decrease in strong ion difference after ANH with 6% hydroxyethyl starch solution, the decrease in pH was nearly the same in both groups. ConclusionsANH with 5% albumin or 6% hydroxyethyl starch solutions led to metabolic acidosis. A dilution of extracellular bicarbonate or changes in strong ion difference and albumin concentration offer explanations for this type of acidosis.

First Clinical Implications of Perioperative Red Cell Volume Measurement with a Nonradioactive Marker (Sodium Fluorescein)

PhD Institute of Anesthesiology, Ludwig-Maximilians-Universitat, Klinikum Grophadern, Miinchen, Germany We measured red cell volume (RCV) with the nonradio- active marker sodium fluorescein (SoF) in 30 patients undergoing gynecological operations. Sixteen patients underwent preoperative isovolemic hemodilution (PIHD). RCV measurements were performed before and after PIHD and at the end of the operation. All RCVs were related to corresponding hematocrit (hct) levels. We report a simplified method for its clinical ap- plication by reducing the number of blood samples re- quired. To validate our method, we compared RCV within the PIHD bags (bag RCV) with the difference of the patients’ RCV before and after PIHD. Bag RCV ob- tained during PIHD (mean 399 -’ 81 mL) was measured with a precision of 4.2% by using SoF. There was a sig- nificant difference (mean 286 ? 401 mL; P < 0.05) be- tween intraoperatively estimated and measured blood loss. The blood loss tended to be underestimated and, in some cases, was underestimated or overestimated sub- stantially. Preoperative and postoperative hct values only offered an imprecise estimation of the patients’ RCV. We conclude that RCV measurement using SoF is a precise method for monitoring changes in RCV dur- ing PIHD and surgical operation. Implications: We measured red cell volume changes of 30 patients with the nonradioactive marker sodium fluorescein before and after hemodilution and postoperatively with a high precision. We frequently found large differences be- tween intraoperatively estimated and measured blood loss. Preoperative hematocrit values offered an impre- cise estimation of the patients’ red cell volume. (Anesth Analg 1998;87:1234-8)

Veränderungen des Blutvolumens während akuter normovolämer Hämodilution mit 5% Albumin oder 6% Hydroxyäthylstärke und intraoperativer Retransfusion

ZusammenfassungFragestellung. Welche Auswirkung hat die akute präoperative normovoläme Hämodilution (ANH) auf das Blutvolumen, den intravasalen Kolloidbestand und den Verlust an Erythrozyten in der perioperativen Phase? Methodik. Bei 20 Patientinnen mit Zervixkarzinom wurde vor Wertheim-Meigs-Operation unter Verwendung von 5%igem Albumin (Albumin-Gruppe; n=10) oder 6%iger Hydroxyäthylstärke (HES; HES-Gruppe; n=10) eine ANH bis zu einem Hämatokrit von 22% durchgeführt. Ab einem intraoperativen Hämatokrit von 18% fand die Retransfusion des Hämodilutionsbluts statt. Gemessen wurden vor und nach ANH, vor Retransfusion und am OP-Ende das Plasmavolumen (Farbstoffverdünnungsmethode mit Indozyaningrün), der Hämatokrit und die Gesamteiweißkonzentration. Das Erythrozytenvolumen (Markierung von Erythrozyten mit Fluoreszein) bestimmten wir vor und nach ANH sowie am OP-Ende. In der HES-Gruppe wurden die HES-Konzentrationen im Plasma und Urin gemessen. Ergebnisse. Nach einem Blutentzug von rund 1500 ml und einer 15% höheren Kolloidinfusion konnte in beiden Gruppen das Blutvolumen während ANH aufrechterhalten werden. Bei einem Blutverlust von rund 1800 ml wurden in beiden Gruppen etwa 150 ml Erythrozyten durch die Hämodilution eingespart. Schlussfolgerungen. Die Double-label-Messungen des Blutvolumens zeigten, dass bei den verwendeten Kolloiden ein 15% höheres Infusionsvolumen in Relation zum Blutentzug Isovolämie nach ANH gewährleistete.AbstractQuestion. What is the impact of acute preoperative normovolemic hemodilution (ANH) on blood volume, intravascular colloid, and loss of red cells in the perioperative period? Methods. In 20 patients undergoing radical hysterectomy, preoperative ANH was performed to a hematocrit of 22% using 5% albumin (albumin group; n=10) or 6% hydroxyethylstarch solution (HES group; n=10). Intraoperative retransfusion of ANH blood was started at a hematocrit of 18%. Plasma volume (indocyanine green-dilution technique), hematocrit, and plasma protein concentration were measured before and after ANH, before retransfusion, and postoperatively. Red cell volume (labelling erythrocytes with fluorescein) was determined before and after ANH and postoperatively. In the HES group hydroxyethylstarch concentrations were measured in plasma and urine. Results. After removal of about 1,500 ml of blood and replacement with 15% more colloid solution, the blood volume was maintained in both groups after ANH. After a mean blood loss of about 1,800 ml, an average of 150 ml of red cells were saved due to ANH in both groups. Conclusions. Double label measurements of blood volume demonstrated that with the colloids used a surplus of 15% of colloid infusion in relation to blood removal was necessary to generate isovolemia after ANH.

Four cases of radical hysterectomy with acute normovolemic hemodilution despite low preoperative hematocrit values.

The study was approved by the institutional ethics committee at our institution with all patients giving their written, informed consent. Four patients from a continuing study with preoperative diagnosis of carcinoma of the cervix are presented. They had a preoperative Hct of ,33%, were ASA physical status I or II, were without cardiovascular, pulmonary, or hormonal dysfunctions, and were scheduled for radical hysterectomy. They fasted for 10 h, and neither preoperative bowel cleansing nor any preoperative infusions were administered before measurement. After the induction of general anesthesia and insertion of central and arterial catheters, baseline measurements of plasma volume (PV), Hct, and RCV were performed. (For measuring procedures, see below.) These baseline measurements showed that all four patients had low preoperative Hct values because of extraordinarily large PVs rather than small RCVs. Therefore, ANH to a target Hct of 20% was performed. A median of 1,300 mL of blood was removed and simultaneously replaced by 1,550 mL of colloid (5% albumin solution or 6% hydroxyethylstarch). After completion of ANH and a steady-state interval of 30 min without any further infusions, simultaneous measurements of PV, Hct, and RCV were performed. After these measurements, the surgical procedure began. The intraoperative transfusion trigger for beginning retransfusion was a Hct of 16%. After having reached this Hct value, the fraction of inspired oxygen was switched from 0.5 to 1.0. All autologous blood was retransfused in every patient late in surgery when major blood loss had ceased. Postoperative measurements of PV, Hct, and RCV were performed immediately after closure of the abdominal wall during a period of stable anesthesia without obvious blood loss. Preoperative PV and Hct measurements before ANH and postoperative measurements were performed in duplicate in a time interval of 30 min without any infusions.