Restrictive use of perioperative blood transfusion does not increase complication rates in microvascular breast reconstruction

Accepted Manuscript Restrictive use of perioperative blood transfusion does not increase complication rates in microvascular breast reconstruction Anne C. O’Neill, MBBCh PhD, Marina Barandun, MD, Jieun Cha, MD MSc, Toni Zhong, MD, MHS, Stefan O.P. Hofer, MD PhD PII:

S1748-6815(16)30061-4

DOI:

10.1016/j.bjps.2016.04.021

Reference:

PRAS 4977

To appear in:

Journal of Plastic, Reconstructive & Aesthetic Surgery

Received Date: 6 January 2016 Revised Date:

24 April 2016

Accepted Date: 26 April 2016

Please cite this article as: O’Neill AC, Barandun M, Cha J, Zhong T, Hofer SOP, Restrictive use of perioperative blood transfusion does not increase complication rates in microvascular breast reconstruction, British Journal of Plastic Surgery (2016), doi: 10.1016/j.bjps.2016.04.021. This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

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Restrictive use of perioperative blood transfusion does not increase complication rates in microvascular breast reconstruction

Anne C. O’Neill, MBBCh PhD

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Division of Plastic and Reconstructive Surgery, Department of Surgery and Surgical Oncology, University Health Network, University of Toronto, Toronto, Ontario, Canada.

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Marina Barandun MD

Division of Plastic and Reconstructive Surgery, Department of Surgery and Surgical Oncology, University Health Network, University of Toronto, Toronto, Ontario,

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Canada and Department of Plastic Surgery, University Hospital of Basel, Basel, Switzerland.

Jieun Cha, MD MSc

Division of Plastic and Reconstructive Surgery, Department of Surgery and Surgical

Canada.

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Toni Zhong, MD, MHS

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Oncology, University Health Network, University of Toronto, Toronto, Ontario,

Division of Plastic and Reconstructive Surgery, Department of Surgery and Surgical

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Oncology, University Health Network, University of Toronto, Toronto, Ontario, Canada.

Stefan O.P. Hofer MD PhD Division of Plastic and Reconstructive Surgery, Department of Surgery and Surgical Oncology, University Health Network, University of Toronto, Toronto, Ontario, Canada. Presented at the Canadian Society of Plastic Surgeons Annual Meeting, Montreal, Quebec, Canada. June 1014. 1

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Abstract Introduction: With increasing appreciation of the possible adverse effects of peri-

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operative blood transfusion, restrictive policies regarding use of blood products have been adopted in many surgical specialties. Although microvascular breast

reconstruction has become a routine procedure, high peri-operative transfusion

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rates continue to be reported in the literature. In this study we examine the impact of our restrictive approach on blood transfusion rates and postoperative

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complications in patients undergoing microvascular blood transfusion. Methods: A retrospective review of patients undergoing microvascular breast reconstruction with abdominal flaps at a single institution was performed. Patient age and body mass index as well as type, timing and laterality of reconstruction was

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recorded. Pre-operative and post-operative hemoglobin and hematocrit were recorded. Peri-operative blood transfusion rates were calculated. Post-operative complication rates were compared between patients with higher and lower post-

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operative hemoglobin levels.

Results: Five hundred and twelve patients were included in this study. The peri-

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operative transfusion rate was 0.98% in this series. There was no significant difference between transfusion rates in unilateral and bilateral reconstructions (0.68 vs 1.36% p=0.08) or immediate and delayed reconstructions (1.02 vs 0.51% p=0.72 and 1.01 vs 1.60% p=0.09 for unilateral and bilateral respectively). Lower post-operative hemoglobin levels were not associated with increased flap related, surgical or medical complications rates.

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Conclusion: A restrictive approach to peri-operative blood transfusion can be safely adopted in microvascular breast reconstruction without compromising flap viability

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or overall complication rates.

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Keywords: Breast Reconstruction; microvascular; preoperative blood transfusion.

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Introduction

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Post mastectomy breast reconstruction has many physical and psychosocial benefits and had rapidly established itself as an integral part of the breast cancer care

pathway for many women.(1) Microvascular free tissue transfer is the current gold

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standard in breast reconstruction as it provides an aesthetically superior result that is natural in both feel and appearance and is associated with high patient

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satisfaction rates.(2) Although breast reconstruction using microvascular transfer of abdominal tissue has become a routine procedure in many centres surprisingly high rates of peri-operative blood transfusion continue to be reported in the literature. A recent study of factors influencing blood transfusion in deep inferior epigastric

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perforator (DIEP) flaps reports a transfusion rate of 18.8% increasing to 28.2% in obese patients.(3) Transfusions were more likely in patients undergoing bilateral reconstruction and in cases with longer operating times. Many other recent studies

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have reported transfusion rates between 8.2% and 80.3% in abdominally based free tissue transfer.(4-8)

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The use of perioperative blood transfusion in free flap surgery is controversial. Older studies indicated that maintaining hemoglobin (Hb) greater than 10g/dL was important for flap survival as it optimised oxygen delivery to the tissues.(9) It has been suggested that pre-operative Hb values less than 10g/dL are a significant predictor of thrombosis and flap failure.(10) Lower post-operative Hb levels have also been associated with increased incidence of medical complications and extended post-operative hospital stay.(11, 12) More recently, however, it has been 4

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shown that peri-operative anemia does not increase flap-related complications in microvascular breast reconstruction.(13, 14) Increasing knowledge of the possible risks associated with transfusion has driven a

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more conservative approach to the use of blood products in medicine in

general.(15-17) Apart from the known risks of disease transmission there is

growing evidence to suggest that blood transfusion is an independent risk factor for

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bacterial post-operative infection in elective surgery.(18-20) There are also

concerns that perioperative blood transfusion may increase recurrence and

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mortality rates in many types of malignancy.(21-23) Blood transfusion is increasingly recognized as an independent risk factor for perioperative morbidity and mortality.(24) A recent study of intra-operative transfusion in free flap surgery, using the NSQIP dataset found transfusion to be significantly associated with higher

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rates of overall complications.(12)

Our centre has a conservative approach to perioperative blood transfusion in autologous breast reconstruction. In accordance with the guidelines of the

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American Society of Anesthesiologist’s guidelines we reserve transfusion for

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patients with Hb <6.0 gram/deciliter (g /dL), those who become symptomatic or those with decreasing Hb suggestive of ongoing blood loss.(25) In this study we examine our institutional perioperative transfusion rate and the impact of our restrictive strategy on surgical and medical post-operative complications.

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Methods

Data Collection: A retrospective chart review of all patients undergoing

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microvascular breast reconstruction using abdominal free flaps at University Health Network, Toronto, Canada between December 2008 and June 2014 was performed. The study was approved by our institutional ethical review board. All patients with

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recorded pre-operative and post-operative (day 1) hemoglobin and hematocrit levels were eligible for inclusion in the study. Data were compiled on patient

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demographics (age, body mass index, comorbidities), surgical procedure (flap type, laterality, timing), blood parameters (pre- and post-operative Hb and hematocrit, intra- or post-operative blood transfusion, units transfused, other blood products received), post-operative complications (flap related, general surgical and general

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medical) and length of hospital stay.

Surgical Procedure: All patients underwent breast reconstruction at Toronto General Hospital or Mount Sinai Hospital, Toronto by one of three staff surgeons (S.O.P.H.,

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T.Z. or A.C.O’N.). Breast reconstructions were performed using abdominal free flaps

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in all cases. Computed tomography angiography was performed on all patients to delineate the perforators preoperatively. A blood-sparing technique was used in all cases with meticulous hemostasis and judicious use of monopolar cautery for initial dissection and elevation of the flaps. Bipolar cautery was used for dissection of the perforators throughout their intramuscular course and ligasure clips were used for ligation of all vascular branches. No formal measures of blood loss were performed intra-operatively. Patients were grouped and screened but not cross-matched 6

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preoperatively. Crystalloid volume replacement was delivered at a rate of 3.5 – 6ml/ kg/ hour in the 24-hour peri-operative period as we have previously determined this to be optimal in minimizing morbidity.(26)

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Statistical Analysis: All statistical analyses were conducted using Statistical Package for the Social Sciences (SPSS, Chicago IL). Data are presented as number and rate

(%) or mean and standard deviation. Parametric and non-parametric variables were

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analysed using χ2 or Fischer’s exact test and ANOVA with Bonferroni correction

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respectively. Values of P <0.05 were considered to be statistically significant.

Results

Five hundred and twelve patients undergoing 732 breast reconstructions were

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eligible for inclusion in the study. The mean age was 50.3 years (range 29-77 years). The mean body mas index (BMI) was 30.1kg /m2 (range 23-42kg /m2). The majority of flaps were DIEP flaps (84%) while the remainder (16%) were

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muscle sparing transverse rectus abdominis muscle (MS-TRAM) flaps. Two hundred

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and ninety two patients had unilateral reconstructions while 220 patients had bilateral reconstructions. Immediate reconstructions were performed in 33.6% of unilateral cases and 45% of bilateral cases. The internal mammary vessels were the recipients in all cases.

The mean pre-operative Hb was 13.3g/ dl (range 9.8-15.8 g/dl) and the mean postoperative Hb was 10.1 (range 5.9-12.8 g/dl) (Table 1). The mean change in Hb was 3.1g/dl (range 0.6-6.9 g /dl) corresponding to a mean reduction of 23.4% (range 7

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4.1-51.6%). The mean pre-operative hematocrit (HCT) was 0.391 (range 0.2930.486) and the mean post-operative HCT was 0.305 (range 0.174-0.486). The mean change in HCT was 0.093 (range 0.005-0.901).

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Two hundred and eighty (54.7%) patients had a Hb ≥10 g/dl on the first post-

operative day while 171 (33.4%) had Hb <10g /dl ≥ 8g /dl and 61 (11.9%) had Hb < 8g/dl.

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The overall post-operative complication rate in this series was 17.0%. Flap related complications were seen in 4.1%, general surgical complications were seen in

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11.7% and general medical complications were seen in 1.2% of patients. The complications are outlined in Table 2. There was no significant difference in complication rates or mean length of stay between the 3 post-operative Hb groups. No patients received intra-operative blood transfusions while 5 patients (0.98%)

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received post-operative transfusions. Four of the patients who received blood transfusion had Hb <8g/dl on the first post-operative day while the fifth had Hb >8g /dl but it subsequently dropped when they developed a hematoma on the

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second post-operative day. The mean post-operative hemoglobin in patients who

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received transfusion was 6.4 g/ dl (range 5.9 – 7.0 g/dl). The commonest indication for transfusion was dyspnea at rest (4 out of 5 cases) while in the fifth case it was Hb <6 g/dl. All 5 patients who received blood transfusions had returned to the operating room for secondary surgery due to surgical complications (3 evacuation of hematoma, 2 venous congestion of flap). Three patients received 2 units of packed red cells while 2 received one unit. All transfused patients were prescribed 2 units as per hospital protocol but in 1 case only one unit was administered due to 8

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fever and in another case the patient refused a second unit as her symptoms of dyspnea had resolved. No other blood products were administered in this patient cohort.

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There was no significant difference between the transfusion rates in unilateral

(0.68%) and bilateral (1.36%) cases (p=0.08) (Table 3). In unilateral cases there

was no significant difference between transfusion rates in immediate (1.02%) and

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delayed (0.51%) cases (p=0.72). Similarly in bilateral cases there was no significant difference between transfusion rates in immediate (1.01%) and delayed (1.60%)

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cases (p=0.09). There was no significant difference between the mean age of transfused and non-transfused patients (49.1 ± 6.4 and 51.2 ± 7.1 respectively, p=0.18). Similarly there was no significant difference between the mean BMI of

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Discussion

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p=0.23).

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transfused and non-transfused patients (29.7± 3.8 and 31.2 ± 4.1 respectively,

Our perioperative transfusion rate of 0.98% is among the lowest reported in the literature. This is a 50% reduction on the transfusion rate reported in an earlier cohort at our centre.(26) Our rates contrast starkly with those reported in recent literature.(3, 6, 7, 27) We consider perioperative transfusion to be an adverse event in microsurgical breast reconstruction and strive to reduce the risk to negligible. All

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patients who received transfusions in this series had experienced surgical complications resulting in excessive blood loss. For many years the decision to transfuse red blood cells was based on the “10/30

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rule” which aimed to keep Hb above 10g/dl and HCT above 30% or 0.3. Increasing awareness of the potential risks of allogeneic blood transfusions led to a re-

evaluation of transfusion protocols in the 1980s, concluding that no single criterion

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should govern the administration of blood products but the decision should consider multiple factors relating to the patients clinical status and oxygen

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delivery.(15) Oxygen delivery (DO2) is determined by the following formula: DO2 = cardiac output X arterial oxygen content

In healthy patients increasing cardiac output can compensate for the decrease in arterial oxygen content that occurs as a result of post-operative anemia. As the

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majority of patients undergoing breast reconstruction surgery are relatively healthy they can be expected to maintain adequate oxygen delivery post-operatively. Many patients develop postoperative tachycardia following microvascular breast

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reconstruction in the absence of other symptoms of hypovolemia.(28) In our centre

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we do not consider tachycardia alone to be an indication for transfusion but rather a physiological response to decreased arterial oxygen content. Normal oxygen delivery rates exceed consumption rates by a factor of four. In the absence of cardiovascular compromise oxygen delivery will theoretically be adequate until the HCT falls below 0.1 due to increased cardiac output, shift of the oxygen-Hb dissociation curve to the right and increased oxygen extraction. The mean postoperative HCT in this study was 0.391 and there were no cases where 10

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HCT fell below 0.1. In the absence of underlying cardiovascular compromise this reduction in HCT should be well tolerated. This study illustrates that strict adherence to the guidelines of the American

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Association of Anesthesiologist’s results in very minimal use of blood transfusions in patients undergoing microsurgical breast reconstruction.(25) Other investigators

identified multiple risk factors for perioperative blood transfusion.(4) Appleton et al

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reported an increased transfusion rate of 28.8% in obese patients.(3) We found no significant difference in mean BMI in our transfused group. Immediate

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reconstructions and bilateral reconstructions have also been found to be associated with increased transfusion rates but we found no significant differences in our cohort.(3, 4). We acknowledge however that the small number of transfused patients in our cohort limits the power of our statistical analysis and the results

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must be interpreted accordingly. We demonstrate that our restrictive approach does not adversely affect outcomes following microvascular breast reconstruction with no significant difference in the rates of microsurgical, general surgical or

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medical complications with lower postoperative hemoglobin levels. Although some

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studies have indicated that postoperative anemia may increase morbidity these findings must be interpreted with caution when considering a healthy population such as patients undergoing breast reconstruction.(11) Previous studies indicate that restrictive transfusion strategies can reduce medical complications following breast reconstruction.(4) Our study did not directly address the relationship between increased operating time and transfusion rates. Appleton et al found increased operative times to be an 11

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important independent risk factor for blood transfusion.(3) While we did not record operative time in our database we did not observe increased transfusion rates in bilateral cases, which we have previously shown to have a significantly longer

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duration than unilateral reconstructions.(26) Similarly we did not objectively measure intraoperative blood loss as part of our study. As peri-operative

transfusion is an extremely rare occurrence at our centre we do not formally

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measure blood loss during the procedure. In cases where transfusion was required it was more likely related to excessive post-operative bleeding (hematoma or

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venous congestion) than intraoperative loss. In addition, while we demonstrated that low post-operative Hb did not adversely affect medical or surgical complication rates we did not examine the impact on patient well-being and quality of life. This has not been studied specifically in a breast reconstruction population but low post-

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operative Hb has been shown to be well tolerated without negative impact on quality of life scores following other elective surgeries.(29) This study demonstrates that a restrictive approach to peri-operative blood

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transfusion can be safely adopted in microvascular breast reconstruction. The

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possible adverse effects of transfusion can therefore be avoided without increasing post-operative complication rates.

Disclosures: The authors have no conflicts of interest to disclose.

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Mean 13.3 g/dL 10.1 g/dL 3.1 g/dL 23.4%

Range 9.8-15.8 g/dL 6.1-12.8 g/dL 0.6-6.9 g/dL 4.1-51.6%

Preoperative HCT Postoperative HCT Change in HCT

0.391L/L 0.305L/L 0.093L/L

0.293-0.486 L/L 0.174-0.378 L/L 0.005-0.900 L/L

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Preoperative Hb Postoperative Hb Change in Hb Loss of Hb (%)

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Table 1: Blood parameters before and after microvascular autologous breast reconstruction.

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Table 2: Complications by day 1 post-operative hemoglobin level.

Flap Takeback

Surgical Complications Hematoma Wound Dehiscence

P- values

21/512 4.1% 3/512 0.6% 4/512 0.8% 14/512 2.7%

6/280 2.1% 0/280 0% 1/280 0.4% 5/282 1.8%

11/171 6.4% 2/171 1.2% 2/171 1.2% 7/171 4.1%

4/61 6.5% 1/61 1.6% 1/61 1.6% 2/61 3.2%

0.62

27/280 9.6% 8/280 2.9% 12/280 4.3% 7/280 2.5%

27/171 15.8% 12/171 7.0% 10/171 5.8% 5/171 2.9%

6/61 9.8% 4/61 6.5% 2/61 3.2% 0/61 0.0%

0.14

6/512 1.2% 2/512 0.4%

3/280 1.1% 0/280 0.0%

3/171 1.8% 2/171 1.2%

0/61 0.0% 0/61 0.0%

0.51

2/512 0.4% 2/512 0.4%

1/280 0.4% 2/280 0.7%

1/171 0.6% 0/171 0.0%

0/61 0.0% 0/61 0.0%

0.84

4.6 ± 1.3

4.2 ± 1.0

4.8 ± 0.8

4.5 ± 1.6

60/512 11.8% 24/512 4.7% 24/512 4.7% 12/512 2.3%

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Wound Infection

Group C Hb < 8

Medical Complications

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Venous Thrombembolic disease Cardiorespiratory

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Other

Length of Stay (days)

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Partial Flap Failure

Group B Hb ≥8<10

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Total Flap Failure

Group A Hb ≥ 10

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Flap Complications

Total

0.92 0.78 0.09

0.09 0.61 0.30

0.31

0.61

0.86