Preoperative haemodilution

Preoperative Management of a Jehovah's Witness Patient Undergoing Head and Neck Surgery With High Risk of Bleeding

ABSTRACT

Surgery in head and neck district is often associated with bleeding as major complication and need of blood transfusions. Homologous blood transfusions may be unacceptable to some patient groups such as the Jehovah's Witness (JW) patients. Refusal of potentially life-saving treatment creates ethical dilemmas for treating clinicians.This is the first report in literature which examines the management and treatment of a female JW patient who underwent major surgical procedure for squamous cell carcinoma of the jaw with a high risk of hemorrage which rejected any possibility of blood and hemocomponent transfusion by virtue of her religious principles.

Blood sparing in craniosynostosis surgery

One of the main risks of craniosynostosis surgery is the possible need for an allogenic blood transfusion (ABT). Most patients are operated on in the first months of life, when physiological conditions are particularly sensitive to even limited blood losses. Furthermore, most surgical techniques proposed in the past were based on extensive craniectomies and cranial remodeling. Because of the known infective and immunologic risks of ABT, in recent years more attention has been dedicated to factors that might help reduce the risk of ABT. We review recent preoperative (ie, erythropoietin administration), intraoperative (ie, acute normovolemic hemodilution, intraoperative blood salvage), and postoperative (ie, clinical monitoring, postoperative blood salvage) anesthesiologic procedures developed with this aim in mind. We also consider operative techniques and technical apparatus that reduce surgical invasiveness, particularly preoperative planning, age selection, and the role of endoscopic assistance and gradual distraction devices.

Acute normovolemic hemodilution

Patients and physicians continue to be motivated to find methods to reduce the use of allogeneic blood. Even though donor screening has increased the safety of donated blood products, autologous blood is the most desirable source of red cells during the perioperative period. The methods commonly used to obtain autologous blood during the perioperative period can be initiated prior to the operative procedure (autologous preoperative donation, acute normovolemic hemodilution) or during surgery (cell scavenging). Acute normovolemic hemodilution (ANH) involves a controlled removal of whole blood immediately prior to the operation. The patient's intravascular volume is maintained with solutions that contain non-red cells. The operative procedure is conducted with a normal blood volume, but with a reduced red cell mass. At the conclusion of the operation, the stored autologous blood is restored to the patient. If operative blood loss is not excessive, the replacement of autologous blood may provide an acceptable red cell mass. In addition to surgical blood loss, some of the key factors in determining how effective acute normovolemic hemodilution will be in limiting allogeneic transfusion are: the patient's initial hematocrit and blood volume; the volume of autologous blood removed prior to the operation; the effectiveness of the hemodilution; and the timing of autologous blood replacement. In contrast to autologous pre-donation, autologous blood removed during acute normovolemic hemodilution is usually stored and re-infused in the operating room.

A prospective randomized study comparing two techniques of perioperative blood conservation: isovolemic hemodilution and hypervolemic hemodilution

We compared hypervolemic hemodilution (HVH) and isovolemic hemodilution (IVH) as means of perioperative blood conservation under standardized conditions. Thirty ASA status I/II adults slated for orthopedic, ear-nose-throat, or general surgery with expected blood loss of >500 mL underwent either IVH (n = 15) or HVH (n = 15). They were hemodiluted to a hematocrit (Hct) of 25% by blood withdrawal and simultaneous polygeline (Hemaccel((R))) infusion (IVH) or by infusing polygeline without blood withdrawal, thus creating hypervolemia (HVH). Further blood loss to a Hct of 20% was allowed before autologous/allogeneic blood transfusion to aim for a 24-h postoperative Hct of > or =25%. Systolic blood pressure (P = 0.0107) and central venous pressure (P = 0.0281) were significantly higher during HVH. The mean difference (MD) between the target postdilution Hct of 25% and the Hct achieved was not statistically significant in either group (MD [95% confidence interval; CI], 0% [-0.7% to 0.7%] for IVH and 0.6% [-0.1% to 1.3%] for HVH). The actual amount of allogeneic blood used was similar in the two groups, with an MD (95% CI) of -7 (-326 to 312), and was significantly less than the corresponding projected amount (MD [95% CI], -581 mL [-753 to -409 mL] in IVH; -376 mL [-531 to -221] in HVH). The two techniques were similar in time taken (MD [95% CI] = 7 min [-0.5 to 14.5 min]), cost incurred (MD [95% CI] = $1.7 (-$4.10 to $7.50]), and volumes of polygeline used (MD [95% CI] = -6 mL/kg body weight [-16 to 4 mL/kg body weight]). This study found IVH and HVH comparable in significantly reducing perioperative allogeneic blood requirements, time needed, and cost incurred. The formula used for achieving the desired HVH appears promising.

IMPLICATIONS

Both hypervolemic hemodilution (HVH) and isovolemic hemodilution (IVH) claim to reduce red blood cell loss during surgery by diluting the patient's blood. This study found both comparable in significantly reducing the exposure to bank blood in the perioperative period, the time needed, and the cost incurred. HVH, being simpler, because it does not involve blood withdrawal, appeared superior to IVH in the healthy adults studied. Larger studies are needed to substantiate the results.

Pulsed venous flow pattern with hemodilution

Venous flow pattern changes and venous flow were assessed in relation to the degree of hemodilution. Femoral vein flow was measured with a duplex scanner in two groups of 11 patients 20 days and 5 days preoperatively, and 1 day postoperatively. In group I, hemodilution was used and patients gave three autologous blood predonations between day 20 and day 5. Perioperative blood loss was reintegrated by electrolyte solution. In group II, hemodilution was not used and autologous blood predonations were not carried out. These patients received a perioperative homologous blood transfusion of 800 mL. Hemoglobin was lower on day 5 (11.3 +/-1.4 vs 13.1 +/-1 g/dL, p<0.05) and on postoperative day 1 (8.9 +/-1.6 vs 10.6 +/-1, p<0.05) in group I. The decrease in hemoglobin was associated with an increase in blood flow and a pulsed venous flow pattern in 14 of 22 veins after autologous blood predonation and in 21 of 22 veins on postoperative day 1 (p<0.05). Increased venous flow in hemodilution is associated with a pulsed venous flow pattern.

Cardiovascular effects of moderate normovolaemic haemodilution during enflurane-nitrous oxide anaesthesia in man

The cardiovascular effects of mild normovolaemic haemodilution during enflurane-nitrous oxide anaesthesia were studied in 20 patients with normal cardiac function before, during and after total hip replacement. After induction of anaesthesia, patients were randomly allocated to one control group (C), or one haemodiluted group (H) where Hct was decreased to 30% by replacement of blood volume by an identical volume of hydroxyethyl starch 200/05. Each patient was monitored with a pulmonary artery catheter allowing the measurement of right ventricular ejection fraction. During haemodilution, stroke index and right ventricular end-diastolic volume index increased from 33.1 +/- 7.9 to 39.3 +/- 7.1 ml.M-2 and from 73.8 +/- 20.3 to 94.9 +/- 18.5 ml.M-2 respectively (mean +/- s.d., both P < 0.05). However, heart rate decreased so that cardiac index did not change. O2 delivery decreased significantly (from 389 +/- 70 to 311 +/- 63 ml.min-1.m-2; P < 0.05), but was not different to the control group. O2 consumption was maintained by an increase in O2 extraction. During the surgical procedure, cardiac index was higher in the haemodiluted group than in the control group, so that O2 delivery was similar in the two groups. O2 consumption tended to be greater in the haemodiluted group. In patients with normal cardiac function, enflurane-nitrous oxide anesthesia could alter the normal physiologic response to mild normovolaemic haemodilution.

Acute normovolaemic haemodilution and idiopathic scoliosis surgery: effects on homologous blood requirements

After the introduction of acute normovolaemic haemodilution(NVHD) in our hospital, we prospectively studied 19 patients managed with moderate NVHD (mean haematocrit 0.28, SD 0.02) during idiopathic scoliosis surgery (mean angle 53.2, SD 16.7 degrees) with the Cotrel-Dubousset instrumentation (CDI). Our standard scoliosis anaesthetic technique was used. Intraoperatively, one patient received one unit of homologous blood. Postoperatively, seven patients received ten units of homologous blood. Homologous blood used was reduced by about 83% for this procedure in our institution. In the assessment of fluid and blood requirements we found physical signs reflecting tissue perfusion and oxygen supply more reliable than the estimated blood loss using the suction bottle and swabs. The similar postoperative complications (nine fever, five atelectasis/pneumonia, one urinary infection, one phlebitis), anaesthetic duration (mean 5.21, SD 1.13) hours, hospitalisation (mean 6.67, SD 1.19) days and return to normal activity (mean 8, SD 7.68) weeks indicate that the NVHD patients did just as well as with our previous regimen when only homologous blood was used.

[Normovolemic hemodilution]

Transfusion of homologous blood to surgical patients is not without risks. Thus, strategies to prevent blood loss must be considered. This article deals with one of them: normovolaemic haemodilution together with its advantages, physiological consequences and technical aspects. In particular, it is important to follow certain inclusion criteria. The technique is safe, effective and relatively easy to implement. In the future, it could be used in non-surgical patients, when it is necessary to increase tissue perfusion.