Alternatives to allogeneic blood use in surgery: acute normovolemic hemodilution and preoperative autologous donation

Fluorine-19 magnetic resonance angiography of the mouse

Purpose

To implement and characterize a fluorine-19 (¹⁹F) magnetic resonance imaging (MRI) technique and to test the hypothesis that the ¹⁹F MRI signal in steady state after intravenous injection of a perfluoro-15-crown-5 ether (PCE) emulsion may be exploited for angiography in a pre-clinical in vivo animal study.

Materials and Methods

In vitro at 9.4T, the detection limit of the PCE emulsion at a scan time of 10 min/slice was determined, after which the T₁ and T₂ of PCE in venous blood were measured. Permission from the local animal use committee was obtained for all animal experiments. 12 µl/g of PCE emulsion was intravenously injected in 11 mice. Gradient echo ¹H and ¹⁹F images were obtained at identical anatomical levels. Signal-to-noise (SNR) and contrast-to-noise (CNR) ratios were determined for 33 vessels in both the ¹⁹F and ¹H images, which was followed by vessel tracking to determine the vessel conspicuity for both modalities.

Results

In vitro, the detection limit was ∼400 µM, while the ¹⁹F T₁ and T₂ were 1350±40 and 25±2 ms. The ¹⁹F MR angiograms selectively visualized the vasculature (and the liver parenchyma over time) while precisely coregistering with the ¹H images. Due to the lower SNR of ¹⁹F compared to ¹H (17±8 vs. 83±49, p<0.001), the ¹⁹F CNR was also lower at 15±8 vs. 52±35 (p<0.001). Vessel tracking demonstrated a significantly higher vessel sharpness in the ¹⁹F images (66±11 vs. 56±12, p = 0.002).

Conclusion

¹⁹F magnetic resonance angiography of intravenously administered perfluorocarbon emulsions is feasible for a selective and exclusive visualization of the vasculature in vivo.

Cardioprotective effects of acute isovolemic hemodilution in a rat model of transient coronary occlusion*

OBJECTIVES

Following isovolemic hemodilution (AIH), lowering blood viscosity induces acceleration of erythrocyte velocity resulting in improved tissue oxygen delivery. Using a rat model of myocardial infarct, we tested the hypothesis that AIH would attenuate myocardial damage due to transient coronary occlusion.

DESIGN

Prospective, randomized, and controlled animal study.

SETTING

Animal research laboratory in a university hospital.

SUBJECTS

Male Sprague-Dawley rats.

INTERVENTIONS

All rats were subjected to 30 mins of left coronary artery occlusion followed by 48 hrs of reperfusion. Before the ischemic period, the anesthetized rats were randomly allocated to undergo either 15 mins of waiting (controls) or AIH to achieve a hematocrit of 30% (AIH-CO) by stepwise blood withdrawal and isovolemic compensation with 6% hydroxyethylstarch 200-0.5.

MEASUREMENTS AND MAIN RESULTS

Hemodynamic variables were comparable in the two groups, except for higher indexes of stroke volume in the AIH-CO group. During coronary occlusion and the reperfusion period, AIH resulted in a lower incidence of fatal ventricular tachyarrhythmia (17% vs. 50% in control group, p < .05) and higher survival at 48 hrs of postreperfusion (83% vs. 42%, p < .05).Preischemic hemodilution significantly attenuated myocardial damage as shown by lower release of cardiac troponin I and reduction in myocardial infarct size as measured by tetrazolin staining. Histologic examination revealed no difference regarding peri-ischemic infiltration with neutrophil granulocytes.

CONCLUSIONS

Our data provide the first experimental demonstration that preischemic moderate AIH confers cardioprotection and improves survival in a rat model of myocardial infarct.

Red blood cell recovery and reinfusion

This article describes the intraoperative washed cell salvage process and principles of cell salvage technology and addresses the parameters that can maximize the effectiveness of the process. Used appropriately, this technique can be used to recover and readminister several blood volumes of red cells.

Cardiovascular response to acute normovolemic hemodilution in patients with coronary artery diseases: Assessment with transesophageal echocardiography

OBJECTIVE

Preoperative acute normovolemic hemodilution induces an increase in circulatory output that is thought to be limited in patients with cardiac diseases. Using multiple-plane transesophageal echocardiography, we investigated the mechanisms of cardiovascular adaptation during acute normovolemic hemodilution in patients with severe coronary artery disease.

DESIGN

Prospective case-control study.

SETTING

Operating theater in a university hospital.

PATIENTS

Consecutive patients treated with beta-blockers, scheduled to undergo coronary artery bypass (n = 50).

INTERVENTIONS

After anesthesia induction, blood withdrawal and isovolemic exchange with iso-oncotic starch (1:1.15 ratio) to achieve a hematocrit value of 28%.

MEASUREMENTS AND MAIN RESULTS

In addition to heart rate and intravascular pressures, echocardiographic recordings were obtained before and after acute normovolemic hemodilution to assess cardiac preload, afterload, and contractility. In a control group, not subjected to acute normovolemic hemodilution, hemodynamic variables remained stable during a 20-min anesthesia period. Following acute normovolemic hemodilution, increases in cardiac stroke volume (+28 +/- 4%; mean +/- sd) were correlated with increases in central venous pressure (+2.0 +/- 1.3 mm Hg; R = .56) and in left ventricular end-diastolic area (+18 +/- 5%, R = .39). The unchanged left ventricular end-systolic wall stress and preload-adjusted maximal power indicated that neither left ventricular afterload nor contractility was affected by acute normovolemic hemodilution. Diastolic left ventricular filling abnormalities (15 of 22 cases) improved in 11 patients and were stable in the remaining four patients. Despite reduction in systemic oxygen delivery (-20.5 +/- 7%, p < .05), there was no evidence for myocardial ischemia (electrocardiogram, left ventricular wall motion abnormalities).

CONCLUSIONS

In anesthetized patients with coronary artery disease, moderate acute normovolemic hemodilution did not compromise left ventricular systolic and diastolic function. Lowering blood viscosity resulted in increased stroke volume that was mainly related to increased venous return and higher cardiac preload.

Allogenic blood transfusion does not predispose to infection after cardiac surgery

BACKGROUND

Many retrospective studies report increased postoperative infection after allogenic blood transfusion. To investigate this phenomenon, we prospectively studied 232 patients undergoing cardiac surgery.

METHODS

Patients were screened daily for evidence of culture positive infections. Wounds were examined daily and defined on the ASEPSIS score. Chest radiographs and white cell counts and differentials were recorded on days 1, 2, and 4. The use of blood products was monitored blindly and independently. Patients were grouped according to transfusion status and compared using chi2 or Fisher's test. Logistic regression analyses were performed to identify predictors of transfusion and infection.

RESULTS

Of 232 patients, 116 (50%) received blood product transfusion. Patients receiving blood had lower preoperative hemoglobin, were older, with a greater proportion of urgent/emergency or revision surgery, and were higher risk. Despite this, there were no differences in the frequency of chest infection (20% versus 15%, p = 0.38), urinary infection (3.5% versus 5.3%, p = 0 0.75), wound infection (3.5% versus 8.0%, p = 0.16), or overall infection (28% versus 30%, p = 0.89) comparing the transfused versus untransfused groups. There was no evidence to suggest that administration of blood products was associated with infection (odds ratio 0.92, p = 0.77).

CONCLUSIONS

The administration of blood per se did not lead to increased postoperative infection. Clinicians should reconsider withholding blood transfusion in patients solely owing to concerns of predisposition to infection.

Postoperative intravenous iron used alone or in combination with low-dose erythropoietin is not effective for correction of anemia after cardiac surgery

OBJECTIVES

The aim of this study was to examine whether intravenous iron III-hydroxide sucrose complex (IHSC) used alone was sufficient to provide rapid correction of anemia after cardiac surgery and whether additional stimulation of erythropoiesis is possible by means of a single low dose of recombinant-human erythropoietin (r-HuEPO) administration.

DESIGN

Prospective, randomized, double-blind study.

SETTING

The study was conducted in a university hospital.

PARTICIPANTS

One hundred twenty American Society of Anesthesiologists II or III patients, who underwent elective cardiac surgery using cardiopulmonary bypass and in whom postpump hemoglobin ranged between 7 and 10 g/dL.

INTERVENTIONS

Patients were divided into 3 groups: group I = control; group II received postoperative intravenous iron supplementation with an iron III-hydroxide sucrose complex (IHSC); and group III received IV iron and a single dose of r-HuEPO (300 U/kg).

MEASUREMENTS AND RESULTS

No significant difference in transfusion needs was observed among the 3 groups (22%, 25%, and 17% of patients transfused in groups I, II, and III, respectively). Hemoglobin levels, reticulocyte counts, and serum ferritin levels were evaluated at different time intervals (until day 30 postoperatively). No side effects because of iron administration were noted in the study. Reticulocyte counts increased rapidly at day 5 (2.24% +/- 1.11%, 1.99% +/- 1.44%, and 3.84% +/- 2.02% in groups I, II, and III, respectively) and decreased after day 15 in the 3 groups. Ferritin levels increased significantly at day 5 in the 2 treated groups (899.33 +/- 321.55 ng/mL in group II, 845.75 +/- 289.96 ng/mL in group III v 463.15 +/- 227.74 ng/mL in group I). In group I, ferritin levels, after a slight elevation on day 5, decreased at day 15 to lower than baseline levels. No significant difference in hemoglobin increase was noted among the 3 groups.

CONCLUSION

Postoperative intravenous iron supplementation alone or in combination with a single dose of r-HuEPO (300 U/kg) is not effective in correcting anemia after cardiac surgery.

Post-operative course of coronary artery bypass surgery patients who pre-donate autologous blood

BACKGROUND

Pre-operative autologous blood donation is used to reduce the need of allogeneic blood in patients undergoing coronary bypass surgery operations, but it is not clear what impact the blood donation has on the post-operative course of these patients.

METHODS

We studied the post-operative course of 210 patients who pre-donated autologous blood before their coronary bypass operation (donors) and of 67 patients who were eligible to pre-donate but did not (controls).

RESULTS

The clinical variables and the technical operative parameters of the patients in the two groups were similar. There was no significant difference between the duration of assisted ventilation post-operatively (756 +/- 197 vs. 802 +/- 395 min; P=0.54) or length of stay in the intensive care unit (1.8 +/- 1.1 vs. 1.7 +/- 0.9 days; P=0.52) of the two groups. The number of autologous units of packed red cells and of fresh frozen plasma (FFP) received by the donors was significantly higher than the number of units of allogeneic packed red cells (1.5 +/- 0.9 vs. 0.3 +/- 0.9; P=0.001) and the units of homologous FFP received by the controls (2.3 +/- 0.8 vs. 0.6 +/- 1; P=0.001).

CONCLUSIONS

We found no evidence that autologous blood donation exerted a negative influence on the post-operative course of patients undergoing coronary bypass surgery. Patients who pre-donated blood received no allogeneic blood products, but the number of autologous blood products received by donors was higher than the number of blood products received by patients who did not pre-donate.

Haemodilutional Effect of Standard Fluid Management Limits the Effectiveness of Acute Normovolaemic Haemodilution in AAA Surgery—Results of a Pilot Trial

OBJECTIVE

To evaluate the impact of standard fluid management on the effectiveness of ANH as a blood conservation method in elective open AAA repair.

DESIGN

Prospective randomised controlled study.

METHODS

Thirty-four patients undergoing elective AAA repair were randomised to have ANH (16) or act as controls (18). Intra-operative cell salvage was permitted in both groups. Haemoglobin (Hb) concentrations were determined at variable intervals peri-operatively. Blood loss and the use of heterologous blood were recorded.

RESULTS

The pre- and post-operative Hb concentrations, surgical blood loss and the use of cell salvage were similar in both groups. Hb concentration (median, range) decreased significantly from pre-operative to aortic clamping (with blood loss <100 ml) in ANH patients from 8.8 (7.5-10.2) to 5.7 (4.2-6.6)mmol/l following ANH but also in controls from 8.6 (7.5-9.7) to 7.0 (4.5-9.0)mmol/l due to fluid infusion (P<0.01 for every comparison). Bank blood requirements were similar: median 2 units in ANH and 2.5 units in control patients (P=0.68).

CONCLUSIONS

Large volumes of fluids infused during AAA repair already conserve blood by the mechanism of hypervolaemic haemodilution. When cell salvage is used with standard fluid management during AAA repair, additional ANH is ineffective in saving blood.

Factors influencing the uptake of technologies to minimize perioperative allogeneic blood transfusion: an interview study of national and institutional stakeholders

BACKGROUND

Alternatives to allogeneic blood transfusion exist and are being used to varying extents in Australian hospitals. Evidence on effectiveness and cost-effectiveness is generally inconclusive and provides a suboptimal basis for policy development.

AIM

To describe the influences on uptake of transfusion technologies as perceived by national and institutional stakeholders.

METHODS

Qualitative interview study. Interview transcripts were coded and analysed independently by at least two researchers. Participants had opportunity to comment on their transcript and the manuscript.

RESULTS

A total of 71 interviews were conducted with representatives of the media, specialist medical societies, consumer special interest groups, the Australian Red Cross Blood Service (ARCBS), government, private health insurers, technology manufacturers, prominent clinicians in the area and a sample of clinicians drawn from hospitals with variable use of blood-saving technologies. Technical advances and acceptance of lower transfusion triggers were identified as the main influences on the decrease in use of allogeneic blood transfusion in the past decade. Participants indicated that patients were most aware and supportive of autologous predonation. Participants noted that 'enthusiasts' were involved in educating about the need for alternatives, negotiating resourcing and maintaining the use of a technology. Funding mechanisms were seen as main barriers to use of alternatives. A discrepancy was noted in the rigour of evaluation and regulation of pharmaceuticals and devices/procedures.

CONCLUSIONS

Uptake of blood transfusion technologies by institutions was dependent mostly on funding arrangements and the presence of an 'enthusiast'. Critical review of the evidence for effectiveness or cost-effectiveness of these technologies was rarely mentioned. Opportunities exist for evidence-based medicine principles to play a greater role in policy decisions in this area.

Acute normovolemic hemodilution for radical prostatectomy: can it replace preoperative autologous blood transfusion?

BACKGROUND

Although preoperative autologous blood donation (PAD) is accepted as a standard of care for radical prostatectomy, it is costly, time-consuming and has risks associated with blood storage. Acute normovolemic hemodilution (ANH) is reported to be less expensive and to preserve blood components more effectively than PAD. In the present study, the efficacy and safety of these two autologous blood-collection techniques were compared.

METHODS

The study included 16 consecutive patients scheduled for radical prostatectomy. The first eight patients underwent conventional preoperative autologous blood donation of 400 mL 1 week before the operation (PAD group) and the second eight patients underwent acute normovolemic hemodilution followed by immediate operation (ANH group). All blood collected was transfused in the perioperative period. Preoperative and postoperative hematocrit levels in these two groups were compared.

RESULTS

There were no differences in preoperative hematocrit, time of operation or operative blood loss between the two groups. In the ANH group, 1080 +/- 160 mL of blood were collected. The postoperative hematocrit level did not differ significantly between the groups. No patient in either group received allogeneic blood transfusion or experienced an adverse event directly related to blood transfusion.

CONCLUSION

The two blood-conservation strategies resulted in similar postoperative hematologic outcomes. Given its advantages, which include lower cost, lower risk and higher convenience, ANH is one of the procedures that may replace conventional PAD for use in radical prostatectomy.

Effect of acute hemodilution on intestinal perfusion and intramucosal pH after shock

BACKGROUND

Restoration of oxygen delivery, especially to the splanchnic bed, is of critical importance during trauma resuscitation. Acute normovolemic hemodilution (ANH) has been used to reduce blood transfusion requirement during elective surgery. The effect of hemodilution on the splanchnic circulation during hemorrhagic shock (HS) is not well defined.

METHODS

Swine were instrumented to measure systemic and splanchnic circulation effects of ANH after HS. The adequacy of the splanchnic circulation was assessed by changes in measured mucosal blood flow, mucosal tonometry, as well as by portal venous blood O2 saturation, portal venous CO2 saturation, and lactate.

RESULTS

ANH after HS resulted in a final hematocrit of 18+/-2%. Superior mesenteric artery blood flow was returned to baseline levels; however, mucosal blood flow was still only 64% of baseline levels. However, at the same time mucosal PCO2 and intramucosal pH as well as portal venous O2 and CO2 saturation had normalized.

CONCLUSION

As long as an adequate intravascular volume is maintained, hemodilution is well tolerated by the gut after HS. Concern about the adequacy of gut perfusion should not be a transfusion trigger after HS.

New transfusion strategies

The "new transfusion strategies" are designed to minimize exposure to allogeneic transfusion while maximizing the use of autologous red cells. While not always possible in all clinical situations, this approach appears to be the current transfusion strategy paradigm. Physician and patient concerns about the risk of transfusion therapy are driving these strategies. When combined with management of the elements of cardiopulmonary physiology responsible for cardiac output and tissue perfusion, the autologous techniques of hemodilution, cell salvage, and predeposit are reasonable strategies for achieving the desired goals of allogeneic transfusion avoidance. Of the 11 policies and interventions proposed by the Blood Management Conference6 several need to be iterated as underpinnings for these strategies. They include: 1. assessing transfusion needs on a patient case basis; 2. transfusions are to be given and effect-benefit assessed before proceeding with additional transfusion; 3. limited exposure to allogeneic blood if possible; 4. minimize perioperative blood loss ranging from surgical technique to decreasing laboratory assessments; and 5. maximize oxygen delivery physiology as a first step in improving basic oxygen delivery.