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Anesth Analg 2004;98:537-542 © 2004 International Anesthesia Research Society doi: 10.1213/01.ANE.0000096193.49714.92
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Abstract |
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There are many methods for preventing allogeneic blood administration during radical retropubic prostatectomy, and many of these methods have been compared with each other, but no studies have compared preoperative autologous donation (PAD) and cell salvage (CS). In this study, we evaluated these two methods in patients undergoing radical retropubic prostatectomy. In a prospective cohort model, allogeneic exposure in patients from one surgeon who routinely had his patients donate blood before surgery was compared with that in patients from a different surgeon who predominantly used CS. Fifty patients were enrolled in the study: 26 in the PAD group and 24 in the CS group. No difference in allogeneic exposure was seen between the two groups. A significant difference was seen in the volume of red blood cells lost (891 ± 298 mL versus 1134 ± 358 mL in the PAD and CS groups, respectively). We conclude that PAD and CS are equivalent in their ability to avoid allogeneic transfusion. Larger surgical blood loss in the CS group would suggest that in a more rigorously designed study, CS might provide better allogeneic avoidance than PAD.
IMPLICATIONS: In this prospective cohort study, cell salvage and preoperative autologous donation were compared with respect to their ability to avoid allogeneic transfusion. There was a suggestion that cell salvage might offer better allogeneic transfusion avoidance.
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Introduction |
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A growing interest in blood conservation has developed in recent years. This interest has been stimulated by an allogeneic blood shortage (1), a concern over the immunosuppressive effects of allogeneic transfusion (2), and the possible transmission of variant Creutzfeldt-Jakob disease through blood transfusion (3). Multiple strategies can be applied to avoid allogeneic transfusion. These primary strategies involve preoperative erythropoietin and iron supplementation, preoperative autologous donation (PAD), acute normovolemic hemodilution (ANH), and the application of cell salvage (CS) systems. These modalities have stimulated interest in the optimal method of providing allogeneic avoidance.
In our institution, patients undergoing radical retropubic prostatectomy (RRP) have had PAD offered as the primary method of allogeneic blood avoidance. An editorial in the journal Transfusion criticized PAD for its cost-ineffectiveness, the large waste of PAD units, and the potential for leaving patients more anemic after surgery than they may have been without PAD (4). Thus, evaluations of alternatives to PAD are needed. Several comparisons have been made between PAD and ANH (5,6). With respect to allogeneic avoidance, these studies showed equivalence between the two techniques, but less cost was found to be associated with ANH. Monk et al. (7) compared ANH (with and without erythropoietin) with PAD and demonstrated that all three blood-conservation strategies resulted in similar allogeneic blood exposure rates in patients undergoing RRP.
A fourth strategy for allogeneic blood avoidance, CS, has not been compared with PAD. In this study, we compared the avoidance of allogeneic blood by using CS when compared with PAD. The hypothesis of this study was that CS would offer superior allogeneic blood avoidance when compared with PAD in patients undergoing RRP.
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Methods |
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After receiving IRB approval and written and verbal consent, this study was initially attempted as a randomized, prospective trial, with randomization at the point of surgical scheduling, or approximately 6 wk before surgery. After 2 yr of very limited enrollment because of strong patient and surgeon bias, the study was re-designed to allow patients to self-select their preferred blood-conservation method. This new design enrolled patients undergoing RRP by one of two surgeons, with enrollment into either the PAD or CS group on the day of surgery. Most patients from one surgeon (EK) chose PAD, whereas all patients from the other surgeon (CZ) were enrolled in the CS group. Patients were excluded if they had preexisting anemia, thrombocytopenia, known coagulopathy, or unstable cardiac or pulmonary disease.
Patients underwent surgical resection of the prostate by the surgeon, who used his standard operative technique. Transfusion of allogeneic blood was modeled on the practice guidelines of the American Society of Anesthesiologists (8). Patients with preexisting pulmonary or cardiac disease received transfusions when the hemoglobin (Hgb) concentration was <10 g/dL. Patients with no preexisting pulmonary or cardiac disease received transfusions when the Hgb concentration was <7 g/dL. Hgb was monitored at the point of care by using the HemoCue B-Haemoglobin analyzer (HemoCue, Inc., Ängelholm, Sweden). Fresh frozen plasma (FFP) was administered when the prothrombin time (PT) or partial thromboplastin time (PTT) was >1.5 times normal. PT and PTT monitoring were performed at the point of care with a Coaguchek Pro DM (Roche Diagnostics, Indianapolis, IN). Platelets were transfused when Sonoclot testing (Sienco, Denver, CO) showed evidence of platelet dysfunction, which was also measured at the point-of-care.
CS was initiated with only CS suction tubing and reservoir. If blood in the reservoir exceeded 800 mL or the patient’s Hct decreased to less than the transfusion guidelines, a 125-mL Latham bowl was set up, and CS processing proceeded; all salvaged blood was re-administered to the patient on processing. Management of the CS device was performed by trained blood bank technicians. Blood was washed with a Hemonetics Cell Saver 5 (Braintree, MA) at 300 mL/min, with a total wash of 1000 mL of normal saline solution at a centrifuge speed of 5600 rpm. At the point of reinfusion of the CS unit, the blood was filtered by using a leukocyte depletion filter (LeukoGuard RS; Pall Biomedical Products Co., East Hills, NY).
PAD was performed per American Association of Blood Banks (9,10) standards regulating PAD. Patients were scheduled for 2 U of predonation, but donations did not occur if a patient’s Hgb was <11 g/dL. PAD units were retransfused by using the same strategy as was used for allogeneic units.
Anesthetic management was limited to epidural analgesia. The epidural catheter was placed at a low lumbar level. Mepivacaine 2% plus fentanyl 2 µg/mL, or mepivacaine 2% with epinephrine 1 µg/mL was used for perioperative anesthesia. After completion of the surgical procedure, a standard pain infusion consisting of bupivacaine 0.06% and fentanyl 1 µg/mL was initiated.
The patients were hydrated during and after surgery with a standard regimen. Approximately 15 mL of lactated Ringer’s solution per kilogram per hour throughout the surgery was administered. Initial blood loss was replaced with either crystalloid in a 4:1 ratio or colloid in a 1:1 ratio. Fluids were administered after surgery at 3.5 mL · kg-1 · h-1 during the first 24 h.
Temperature was maintained during surgery with the use of upper-body forced-air convection warming devices set to 41°C and blood warmers. Core body temperature was monitored with a rectal temperature probe placed after anesthetic induction.
The volume of red blood cells lost (RBC-lost) during surgery was calculated by a method previously described by Goodnough et al. (11). For each case, this was calculated by the following formula:
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where the BV of the patient was calculated by the method of Nadler et al. (12) Hctpre was the Hct at the start of surgery, whereas Hctpost was the Hct at hospital discharge. RCVolumetransfused was modified to reflect that red cells could be added by allogeneic transfusion, PAD, or CS. RCVolume for CS was calculated by multiplying the CS returned volume by the Hct of each returned unit. The RCVolume of PAD was estimated by using the previously published value of 186 mL/U, whereas the RCVolume of an allogeneic unit was estimated as 200 mL/U (13).
The primary outcome end-point was the number of allogeneic blood products administered. Secondary end-points included the following: the number of autologous units transfused/wasted, volume of crystalloid or colloid used in the operating room (OR) and 24 h after surgery, discharge Hct, and hospital length of stay. In addition, hemodynamics (mean arterial blood pressure [MAP] and heart rate) were continuously measured during the operative period and for the first hour in the recovery room. MAP of <20% of the baseline MAP for >5 min was compared. Postoperative fever (>38°C), serous discharge, wound erythema, wound dehiscence, and postoperative duration of antibiotic use were also recorded. Finally, pre- and postoperative serum electrolytes (Na+, K+, Cl-, and HCO3), blood urea nitrogen, and creatinine were measured by using hospital laboratory services.
The 
2 test (or Fisher’s exact test, if the expected cell counts were small) was used to compare the difference between groups on categorical variables. Student’s t-test (or Wilcoxon’s ranked sum test, if variables failed the normal assumption) was applied to compare the continuous variables. A P value of <0.05 was considered statistically significant. Data are reported as mean ± SD unless otherwise noted.
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Results |
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Twenty-six patients were enrolled in the PAD group and 24 in the CS group. One patient in the CS group was excluded from analysis because the blood loss for the case was 9000 mL, which was more than 4 SD outside of the mean blood loss for the study.
The PAD and CS groups were comparable in their demographic and surgical characteristics, cardiac risk factors, and chronic medications, although the PAD group had a significantly more frequent incidence of hypercholesterolemia (Table 1). There was no difference in Hgb values (14.8 ± 1.1 g/dL and 14.5 ± 1.1 g/dL for the PAD and CS groups, respectively) when patients were initially scheduled for surgery, but on presentation to the OR, after PAD patients had predonated their blood, the PAD group had Hgb values (13.4 ± 1.1 g/dL) that were significantly less than those of the CS group (14.5 ± 1.1 g/dL; P = 0.001). The PAD group patients were discharged with significantly lower Hgb (8.9 ± 1.1 g/dL) than were the CS patients (10.1 ± 1.4 g/dL; P = 0.002). RBC-lost showed a significant difference in blood loss between the two groups; the CS group lost more RBCs than did the PAD group, yet they left the hospital with a significantly higher Hct (Table 2). No differences were seen in pre- and postoperative electrolyte (Na+, K+, Cl-, and HCO3) or renal function (blood urea nitrogen and creatinine) values.
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For the PAD group, 48 U of packed red blood cells (PRBC) were collected, and 24 (50%) of the units were transfused back to the donor. In addition, 10 U of autologous FFP were generated from the donated units, from which 2 U were retransfused. For the CS group, an average of 668 ± 417 mL of blood was returned to the patient. In one case, no processing was performed because the patient’s blood loss did not meet processing criteria. For allogeneic units, no difference was found between the two groups in transfusion of PRBC, FFP, or platelet use. Of the allogeneic units transfused, the PAD group used 2 U of PRBC and 2 U of FFP in three patients, whereas the CS group had 5 U of PRBC units transfused into 5 patients. No difference was found in crystalloid or colloid use.
No difference between the PAD and CS groups was seen in any of the perioperative hemodynamic variables. No difference was seen in the incidence of postoperative fever, serous wound discharge, wound erythema, or wound dehiscence. A significant difference in postoperative duration of antibiotic use was seen: the PAD group was placed on antibiotics for 13.2 ± 0.9 days, whereas the CS group received antibiotics for 14.4 ± 1.6 days.
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Discussion |
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TopAbstractIntroductionMethodsResultsDiscussionReferences |
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For the two study groups, no difference in allogeneic transfusion was seen; however, the blood loss in the CS group was significantly more than it was for the PAD group. The CS group had a mean RCVolume loss that was 242 mL more than in the PAD group. This difference of 242 mL of blood loss is approximately equivalent to 1 U of PRBC. At a minimum, one can conclude that there was no difference in allogeneic avoidance for the two cohorts.
Most patients from one surgeon (EK) chose to be in the PAD group, whereas all patients from the other surgeon (CZ) chose to be in the CS group. Comparable demographic and presurgical characteristics between the two groups would suggest that the patient populations were equivalent; however, the significant differences in operative blood loss would suggest that caution be used when interpreting the allogeneic transfusion rates in the two study groups.
In addition to tolerating a larger blood loss than the PAD group, the CS patients left the hospital with a significantly higher Hct than did the PAD group. The advantage of higher discharge Hcts was highlighted by Fleisher et al. (14), who found that patients who underwent transfusion at a low Hgb value of 7.5 g/dL, as opposed to a group that underwent transfusion at an Hgb of 10 g/dL, were significantly more fatigued and reported a worse quality of life on discharge. It should be noted that this difference in discharge Hct may have been changed if all of the PAD units had been retransfused. Additionally, the study design may have contributed to this discrepancy through different transfusion triggers. For the PAD group, the blood was transfused when traditional transfusion triggers were crossed, whereas in the CS group, blood was processed and re-administered when 800 mL of blood was lost or a traditional transfusion trigger was crossed. Thus, CS blood may have been administered at a different circulating Hgb level. This difference in transfusion strategy was decided on primarily for two reasons. First, surgeon and anesthesiologist compliance with the protocol would have been difficult when large quantities of blood had accumulated in the CS reservoir yet a transfusion trigger had not been crossed. The reasoning was that the shed blood could not be saved for future use, as could the PAD unit. Second, the transfusion of PAD blood is perceived to incur the additional risk of clerical error and possible transfusion error, so it is easier to obtain compliance with recognized transfusion triggers.
CS may offer some advantage economically over PAD in that it is a point-of-care blood-conservation technique. A study comparing ANH with PAD in RRP patients advocated the advantage of point-of-care techniques (15). This sort of service has been advocated as a cost-saving measure (16). Like normovolemic hemodilution, CS offers point-of-care service. The value of bedside blood conservation strategies is illustrated in Figure 1, which is a histogram illustrating the frequency of specific levels of blood loss during the RRPs in this study. It illustrates a broad range of blood loss with a median of 910 mL. In general, if a patient presents with a reasonable starting Hct and a normal BVolume, 
910 mL of blood loss should not lead to allogeneic transfusion in most patients. In patients who have predonated blood and 910 mL of blood is lost, then resources are expended that might not otherwise have needed to be expended. This point is highlighted by the 50% rate of PAD unit discard seen in this study. Comparatively, CS can be offered in a financially tiered approach. In our institution, CS was initiated with just a blood-collection reservoir. By doing so, the resources expended were minimized in case of minimal blood loss. In our institution, the cost of this setup is less than the cost of a type and cross for 2 U of PRBC and dramatically less expensive than 2 U of PAD blood. If the patient’s Hct decreased to less than 30%, then the Latham bowl and tubing were set up and blood processing was initiated. In this way, 60% of the disposable cost is saved if the blood loss is not significant.
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).Because no previous studies have been performed that compared PAD and CS, other possible differences between the two techniques were postulated. It was proposed that electrolyte differences might be seen because CS blood is composed of red blood cells suspended in saline. It was also proposed that infection rates might be different, because it is often recognized that CS blood is frequently contaminated with bacteria. Finally, it was believed that PAD might affect hemodynamics differently than CS, so this was evaluated with continuous MAP measurement throughout surgery. For all of these postulated differences, no differing effects were found.
The extensive recent interest in blood-conservation strategies makes the lack of comparisons between CS and the other techniques a curiosity. Extensive work has been performed comparing PAD and ANH in RRPs. The lack of an equivalent comparison between PAD or ANH and CS may relate to a fear of using CS in a cancer operation. The manufacturers of CS equipment have historically recommended against use of this technology in tumor surgery for fear of entraining tumor cells into the CS blood and the theoretical metastatic spread of tumor that might result. This theoretical fear appears to be unsupported by clinical studies. In fact, multiple studies support the removal of tumor cells during CS when CS is used in combination with a leukocyte-depletion filter (17–20). Gray et al. (21), in a historical cohort study, compared the incidence of biochemical recurrence rates between 101 patients who received PAD and 62 patients who received CS. Three years after surgery, they found no difference between the two groups in progression of disease. In a similar study, Davis et al. (22) compared 87 CS patients, 264 PAD patients, and 57 patients who received no transfusion during RRP. In this study, no association between type of transfusion technique and cancer recurrence was found at an average of 40 months of follow-up. Thus, CS in RRP appears to be a safe alternative to PAD.
Despite the nonrandomized cohort study design, it appears that CS and PAD may offer similar blood avoidance opportunity; however, the lack of randomization and potential introduction of surgeon bias would suggest that further comparisons of these two techniques are warranted. Comparisons between ANH and CS are also needed.
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Acknowledgments |
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Supported by the General Medical Sciences Research Planning Council, Cleveland Clinic Foundation.
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References |
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- Edelman MJ, Potter P, Mahaffey KG, et al. The potential for reintroduction of tumor cells during intraoperative blood salvage: reduction of risk with use of the RC-400 leukocyte depletion filter. Urology 1996; 47: 179–81.[Web of Science][Medline]
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