Augmented autologous transfusions in major reconstructive spine surgery

Elevated preoperative blood pressure and its relationship to intraoperative mean arterial pressure and blood loss in posterior spinal fusion for adolescent idiopathic scoliosis

PURPOSE

The relationship between preoperative blood pressure (BP) and intraoperative mean arterial pressure (MAP) and estimated blood loss (EBL) in pediatric spine surgery is currently unknown. The objectives of this study were to determine if elevated preoperative BP is associated with elevated intraoperative MAP, EBL, and percentage estimated blood volume (EBV) lost, and to determine if intraoperative MAP is associated with percentage of EBV lost during posterior spinal fusion (PSF) for adolescent idiopathic scoliosis (AIS).

METHODS

This is a retrospective cohort analysis of 209 patients undergoing PSF for AIS between 2016 and 2019 by a single surgeon. Data extracted included demographic characteristics, preoperative systolic and diastolic BP, continuous intraoperative MAP measured by arterial line, EBL, radiographic, and surgical characteristics. Time points of interest for MAP included incision and exposure. Elevated BP was defined as > 1 standard deviation above the mean BP of patients included in the study, and elevated MAP was defined as > 65 mmHg.

RESULTS

Elevated preoperative systolic BP was associated with elevated MAP at incision (p = 0.002). Patients with elevated preoperative diastolic BP had significantly higher MAP at exposure and throughout the procedure (p = 0.04). MAP > 65 at incision was associated with a 5% increase in EBV lost (p < 0.001).

CONCLUSIONS

Patients with elevated preoperative BP parameters have increased MAPs at incision, exposure, and throughout surgery. Elevated MAP at incision is associated with an increased percentage of EBV lost in a small number of patients undergoing PSF for AIS.

Perioperative blood conservation strategies for major spine surgery

BACKGROUND

Orthopedic surgery, especially spine and spinal deformity surgery, may be associated with high perioperative blood loss. In order to reduce the risk of excessive blood loss and unnecessary blood transfusions, strategies such as Patient Blood Management including goal-directed coagulation management have been developed.

RECENT FINDINGS

Adverse effects of allogeneic blood transfusions have been shown for most surgical fields including orthopedic surgery. Several efforts have been made to increase the preoperative red blood cell (RBC) mass, to reduce the intraoperative blood loss, and to use restrictive transfusion triggers in order to minimize or avoid RBC transfusions. Measures to reduce intraoperative blood loss include new surgical techniques, use of cell salvage where possible, bedside coagulation management with point-of-care devices, substitution of coagulation factors, antifibrinolytic agents, and desmopressin, induced hypotension, and avoidance of hypothermia.

SUMMARY

Blood conservation in spinal surgery is a multidisciplinary approach and the efficacy of most single measures has been shown. Cost-effectiveness and the benefits of long-term patient outcomes are the subjects of current and future research.

Practice guidelines for perioperative blood management: an updated report by the American Society of Anesthesiologists Task Force on Perioperative Blood Management*

The American Society of Anesthesiologists Committee on Standards and Practice Parameters and the Task Force on Perioperative Blood Management presents an updated report of the Practice Guidelines for Perioperative Blood Management.

Supplemental Digital Content is available in the text.

Preoperative acute normovolemic hemodilution: a meta-analysis

BACKGROUND

Acute normovolemic hemodilution (ANH) involves withdrawal of whole blood with concurrent infusion of fluids to maintain normovolemia. The aim of this study was to quantify the efficacy and safety of preoperative ANH with a systematic review and meta-analysis.

STUDY DESIGN AND METHODS

Randomized controlled trials were identified through MEDLINE (1966-2002) and the Cochrane Controlled Trials Database and with hand searching of journals. All trials of preoperative ANH reporting on allogeneic transfusion, bleeding, or adverse outcomes were included. Paired reviewers independently abstracted data. Outcomes were pooled using random-effects models.

RESULTS

A total of 42 trials compared hemodilution to usual care or to another blood conservation method. The risk of allogeneic transfusion was similar among patients receiving ANH and those receiving usual care (relative risk [RR], 0.96; 95% CI, 0.90-1.01), or another blood conservation method (RR, 1.11; 95% CI, 0.96-1.28). Hemodiluted patients, however, were transfused from 1 to 2 fewer units of allogeneic blood. They had less total bleeding than patients receiving usual care (91 mL; 95% CI, 25-158 mL), although more intraoperative bleeding. Only one-third of studies reported on adverse events.

CONCLUSIONS

The literature supports only modest benefits from preoperative ANH. The safety of the procedure is unproven. Widespread adoption of ANH cannot be encouraged.

Quantifying risk of transfusion in children undergoing spine surgery

BACKGROUND CONTEXT

The risks and costs of transfusion are a great concern in the area of pediatric spine surgery, because it is a blood-intensive procedure with a high risk for transfusion. Therefore, determining the predictors of transfusion in this patient population is an important first step and has the potential to improve upon the current approaches to reducing transfusion rates. In this study, we reveal several predictors of transfusion in a pediatric patient population undergoing spine surgery. In turn, we present a general rule of thumb ("rule of two's") for gauging transfusion risk, thus enhancing the surgeon's approach to avoiding transfusion in certain clinical scenarios.

PURPOSE

This study was conducted to determine the main factors of transfusion in a population of pediatric patients undergoing scoliosis surgery. The goal was to present an algorithm for quantifying the true risk of transfusion for various patient groups that would highlight patients "at high risk" for transfusion. This is especially important in light of the various risks associated with undergoing a transfusion, as well as the costs involved in maintaining and disposing of exogenous blood materials.

STUDY DESIGN/SETTING

This is a retrospective review of a group of children who underwent scoliosis surgery between 1988 and 1995 at an academic institution.

PATIENT SAMPLE

A total of 290 patients were analyzed in this study, of which 63 were transfused and 227 were not.

OUTCOME MEASURES

No outcomes measures were used in this study.

METHODS

A retrospective review of 290 patients presenting to our institution for scoliosis surgery was conducted, with a focus on socioclinical data related to transfusion risk. Univariate analysis and logistic regression were used to quantify the determinants of transfusion risk.

RESULTS

Univariate analysis identified many factors that were associated with the risk of transfusion. However, it is clear that several of these factors are dependent on each other, obscuring the true issues driving transfusion need. We used multivariate analysis to control for the various univariate predictors of transfusion. Our logistic regression model suggested that the type of scoliosis (odds ratio [OR], 2.02; 95% confidence interval [CI], 1.07 to 3.82), degree of curvature (OR, 1.012/degree curve; 95% CI, 1.01 to 1.03), and use of erythropoietin (OR, 0.29; 95% CI, 0.14 to 0.62) were the main determinants of transfusion risk for our population.

CONCLUSIONS

The main risk factors of transfusion were used to formulate a simple algorithm, which can be used to quantify transfusion risk and to guide efforts to avoid transfusion in children undergoing spinal surgery. Given a 10% baseline risk for transfusion, our "rule of two's" indicates that each risk factor approximately doubles the chance of transfusion, whereas the administration of recombinant human erythropoietin roughly halves the risk of transfusion.

Intraoperative autotransfusion in hip arthroplasty

Two groups of patients having primary or revision total hip replacement were studied during a period of 11 months. The first group of 40 consecutive patients consented to have whole blood collected coincident with acute normovolemic hemodilution. An inventory of autologous red blood cells, plasma, and platelets was prepared in the operating room as a preliminary to surgery. Subsequently, the same supplies and equipment were used for autotransfusion intraoperatively. In a case-control study, another 40 patients having total hip replacements were matched for age, gender, and weight. The second group of patients refused hemodilution and received autotransfusion alone. The perioperative transfusion requirements of the two groups were compared. The total blood product donor exposure rate of the first group was 1/4 of the controls (0.6 and 2.4 donor units per patient, respectively). The average length of stay in the hospital after surgery for the first group was shortened significantly (6.2 versus 8.4 days), possibly from less immunogenic insult associated with increased transfusions of autologous blood products. Hemodilution, followed by autotransfusion, was cost effective in primary and revision total hip replacements, autotransfusion alone was cost effective only in revision arthroplasty.