Blood loss and replacement in total hip arthroplasty: a multicenter study P.T.C.Y. TOY,E.B. K A P w ,P.A. MCVAY,S.J. LEE, R.G. Smuss, L.C. STEHLING, AND THE PREOPERATIVE AUTOLOGOUS BLOODDONATION STUDYGROUP To determine blood loss, the number of transfusions, and the hemoglobin levels achieved in patients via transfusion in the course of total hip arthroplasty, 324 patient records from 1987 through 1989 were reviewed at three university and three community hospitals. Calculated blood loss was 3.2 k 1.3 units in rimary procedures and 4.0 & 2.1 units in revision procedures (mean f SD). d 7 7 7 red cell units transfused, 455 (59%) were autologous units. Transfused patients received 2.0 f 1.8 units for primary procedures and 2.9 f 2.3 units for revision procedures (mean 2 SD). The maximum number of units given to 95 percent of the transfused patients was 4 for primary procedures and 6 for revision procedures. The mean postoperative hemoglobin level after all transfusions was 103 to 110 g per L, re ardless of patient age roup or physical status, autolo ous donor status, or hospid No difference in len t f of hospital stay was observer?for patients less than 65 ears old with hemoglobn concentrations of 80 to 139 g per L at discharge. TRANSthSION 1992;32:6367.

Abbrevlatlons: ASA = Amerlcan Society of Anestheslologlsts; Hb = hemoglobln; Hct = hematocrlt; Postop Hb/Hct = po8toperatlve hemoglobln and hematocrlt; Prsop Hb/ Hct = preoperatlve hemoglobln and hemaocrlt; RBC(s) = red cell(s); THR = total hlp replacement.

Material and Methods

THENUMBER OF RED CELL (RBC) units for which a need is anticipated during surgery has been based on the RBC transfusion history of patients who previously underwent the With the increased awareness since 1985 of transfusion-associated risks, transfusions may be administered more cautiously,6 autologous RBCs are used, and lower hemoglobin (Hb)goals of 80 to 100 g per L are advocated, if the clinical status of the patient warrants it.' Therefore, the number of RBC transfusions administered in the past may not be the standard for current practice. The purposes of the present study of patients undergoing elective total hip replacement (THR)were to determine the amount of blood lost during the entire hospitalization, to determine the number of RBC transfusions given, and to determine the Hb concentrations achieved in THR patients with transfusion.

Elective surgery patients who underwent either primary or revision unilateral THR were evaluated at three university and three community hospitals. The study periods at each of the six hospitals from 1987 through 1989 ranged from 7.5 to 16 months. Included from this group were all autologous blood donors and patients who did not donate blood for autologous use but who were considered by the study group as eligible to do so: these patients were 212 years of age, had Hb 2110 g per L, had American Society of Anesthesiologists (ASA) physical status of 1 to 3, and had not been hospitalized during the previous 5 weeks.

Blood loss We obtained the intraoperative blood loss estimate of the anesthesiologist from the anesthesia record or operative note. In addition, we calculated the amount of blood lost during the entire hospitalization. To do this, we assumed that blood volume was 67.8 mL per kg for men and 62.3 mL per kg for womens (height was not always available) and that blood volumes were unchanged by surgery, that is, that preoperative and 272-hour postoperative blood volumes were the same. We also assumed that there was 200 mL of packed RBCs in 1 homologous blood unit and 177 mL of RBCS in 1 autologous blood unk9 We assumed that the hematocrit (Hct) reflected the total RBC volume, because Huber et al.'O found a good correlation between Hct from 0.20 to 0.50 and the total RBC volume. Conditions that alter this relationship include splenomegaly, pregnancy, nephritis, and cirrhosis, which were unlikely to occur in our patient population. We assumed the b0dy:venous Hct ratio was 0.91."

From the Department of Laboratory Medicine, University of California at San Francisco, San Francisco, California; the Northern California Cancer Center, Belmont, California; the Dcpments of Pathology and Pediatrics, University of Iowa College of Medicine, Iowa City, Iowa; and the Department of Anesthesiology, SUNY Health Science Center, Syracuse, New York. Supported by Public Health SeMce Award R 0 1 HU6715 and Transfusion Medicine Academic Awards KO7 HL01270, KO7 HLO1257, and KO7 HU1426 from the National Heart, Lung. and Blood Institute, NIH. Received for publication January 30, 1991; revision received May 23. 1991, and accepted June 3, 1991.

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Included in this calculation were patients for whom the following data were available: weight, preoperative Hb and Hct (Preop Hb/Hct), and last Hb/Hct 4 to 14 days after the operation (Postop Hb/Hct), determined after all transfusions have been given. We calculated the blood loss as follows: 1. Preop RBC volume = Preop Hct x blood volume x 0.91 2. Postop RBC volume = Postop Hct x blood volume x 0.91 3. Change in RBC volume = Preop RBC volume - Post4.

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op RBC volume Transfused RBC volume = number of homologous RBC units transfused x 200 mL number of autologous RBC units transfused x 177 mL Total RBC volume lost = change in RBC volume + transfused RBC volume Total RBC units lost = total RBC volume lost/200 Percentage of RBC volume lost =

+

Total RBC volume lost x 100%. Preop RBC volume In this calculation, we excluded patients with massive blood loss (210 units of RBCs), because such loss was probably unexpected; patients in whom intraoperativeblood salvage was used; and patients for whom a lack of data on Preop Hb, Postop Hb, or weight precluded calculation of blood loss. Coagulation test results were not always available and were not part of this study.

Number of transfusions and transfusion goals We used blood bank and medical records to determine the number of transfusions given from the day of surgery until discharge. In patients who were transfused, the Postop Hb was determined after all transfusions had been given. We used only those Hb values from 4 to 14 days after the operation.

Statbtical methob We used the t test to compare means. To determine the factors associated with RBC volume lost (total and percentage), we performed analysis of covariance and multiple linear regression using a software package (Statistical Analysis System, SAS Institute Inc., Cary, NC).

Results The study included 324 unilateral THR procedures. All patients survived and were discharged. Forty-seven percent of the patients were male, and the mean ( fSD)age was 63 -C 15 years.

Blood loss Table 1 shows that the mean blood loss was 34 percent of RBC volume in primary THR and 43 percent in revision THR. For some patients, the anesthesiologist’s estimate of intraoperative whole blood loss was available; it was 738 2 549 mL (n = 235) and 943 f 604 mL (n = 70), respectively, for primary and revision THR (mean 2 SD). Among primary THR patients, greater RBC volume loss was associated with higher Preop Hb concentration, heavier weight, and younger age. However, only a weak correlation was found (r2 = 0.24). Surgeon, patient gender, autologous donor status, and blood loss were not significant factors. The percentage of RBC vol-

Table 1. Calculated red cell (RBC) volume lost in total hip arthmplasfy (THR) patients Mean Primary THR (n = 239) RBC volume lost 635 Units lost 3.2 Percentage of RBC volume lost 34 Revision THR (n = 70) RBC volume lost 797 Units lost 4.0 Percentage of RBC volume lost 43

f

SD

Median

f 259 mL 572 mL f 1.3 2.8

95th mrcentile 1100 mL 5.5

f 14% 2 416

f

mL

2.1

696 mL 3.5

1633 mL 8.1

f 20%

ume lost was greater for younger and thinner patients (rZ = 0.10).

Number of transfitsions Patients received a mean ( 2SD) of 2.0 2 1.8 units for primary and 2.9 5 2.3 units for revision procedures. The maximum number of units given to 50 percent .of transfused patients undergoing primary THR was 2; the maximum number given to 95 percent of transfused patients undergoing the same procedure was 4. In revision THR, the maximum number of units given to 50 percent of transfused patients was 3 units; the number of units given to 95 percent of patients was 6. Tables 2 and 3 provide data on transfusion in autologous blood donors and in patients who did not make autologous blood donation. University and community hospitals did not differ in the number of transfusions administered. Of 777 RBC units transfused, 455 (59%) were used from autologous donations, and 322 (41%) from homologous donations. No plasma or platelet transfusions were given.

RBC transfusion goal In untransfused patients undergoing primary and revision THR, the mean ( k SD)Postop Hb concentrations prior to discharge were, respectively, 109 f 16 and 103 f 18 g per L.

In transfused patients, the mean Postop Hb concentrations were 103 to 110 g per L in three age groups (18-39, 40-59, 60-89 years) in autologous donors and nondonors, and at each of the six hospitals. The mean (2SD) Postop Hb for patients with ASA status 1 (n = 25), 2 (n = 106), and 3 (n = 27) was 107 -C 13 g per L, 109 f 12 g per L, and 105 f 90 g per L, respectively. The mean ( f SD)Postop Hb in patients who received only intraoperative transfusions (n = 55) was 103 f 12 g per L, as compared to 110 2 11 g per L for those who received postoperative transfusions (n = 110), p 3). Only patients who donated autologous blood or who were considered eligible to do so were included. Other investigators have reported similar procedures for which smaller volumes of blood were administered.

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Nelson and Bower” performed 65 primary and 24 revision THR procedures in Jehovah’s Witness patients, none of whom were given a transfusion. They used an anterolateral approach, did not perform an osteotomy of the greater trochanter, and used hypotensive anesthesia to decrease blood loss. Such approaches were not used for the patients in this study. Gneskiewicz et a1.16 reported a lower mean transfusion of 1.7 units in 189 patients undergoing unilateral primary and revision procedures. However, they did not include postoperative transfusions administered after 24 hours. Higher transfusion volumes were reported by McMurray et al. I* Average total volumes of homologous blood transfused when intraoperative blood salvage was not used were 914 and 1391 mL in primary and revision THR, or 4.6 and 7.0 units if the volumes represent packed RBCs (200 mL RBCshnit). The mean Postop Hb concentrations were 114 and 113 g per L, respectively, in primary and revision THR patients. Their study showed a savings of 1 unit in primary and 2 units in revision THR when intraoperative blood salvage was used. Two s t u d i e ~ ~of~ *patients ’ ~ who underwent qperation between 1982 and 1985 reported similar mean numbers of units transfuseds and mean discharge Hct values. One study17 reported mean transfusion of 3.1 autologous units and 3.9 homologous units in two groups of patients who underwent THR procedures of unspecified type. The mean postoperative Hct values were 0.32 for the group receiving autologous units and 0.31 for those receiving homologous units. A second study1* of primary THR patients reported mean transfusions of 1512 and 1539 mL, respectively, in homologous and autologous transfusion groups, an amount equivalent to 3 units, as the stated volumes appear to represent whole blood (500mL per unit). The average Postop Hct in these patients was 0.33. These transfusion goals are similar to those in our study patients who underwent surgery between 1987 and 1989, and they suggest that transfusion goals have not changed since the early 1980s. Average posttransfusion Hb concentrations were between 103 and 110 g per L in this study at all six hospitals, in ASA status groups 1 through 3, and in patients between 18 and 89 years of age. This was surprising, given the conclusions of a National Institutes of Health consensus conference, reported during the study period,’ that Postop Hb concentrations