Variation in Transfusion Practices and the Association with Perioperative Adverse Events in Patients Undergoing Open Abdominal Aortic Aneurysm Repair and Lower Extremity Arterial Bypass in the Vascular Quality Initiative

Association of Anemia and Transfusion with Major Adverse Cardiac Events and Major Adverse Limb Events in Patients Undergoing Open Infrainguinal Bypass

BACKGROUND

Anemia is highly prevalent in patients with peripheral vascular disease and has been associated with postoperative cardiac events and mortality and adverse limb events after revascularization procedures. Allogenic blood transfusions have also been associated with adverse events including hospital-acquired infections, cardiac morbidity, and reduced survival. The aim of this study was to evaluate the impact of blood transfusion on major adverse cardiac events (MACE) and major adverse limb events (MALE) in patients undergoing infrainguinal lower extremity bypass (LEB) operations.

METHODS

We performed a retrospective cohort analysis of patients undergoing infrainguinal LEB in the Society for Vascular Surgery Vascular Quality Initiative database between 2003 and 2020. Patients were first grouped by their preoperative hemoglobin (Hgb) number (severe anemia: Hgb 7-10 g/dL; moderate anemia: 10-12 g/dL; normal Hgb: >12 g/dL) and then stratified by their transfusion status (perioperative transfusion versus no perioperative transfusion). Primary end points were MACE, defined as myocardial infarction, new congestive heart failure, dysrhythmia, or stroke in the postoperative period, and MALE, defined as return to operating room for thrombosis, loss of primary patency on follow-up, and major ipsilateral amputation on follow-up. Secondary outcomes included wound complications, graft infections, 30-day mortality, and 1-year survival. Outcomes were compared between patients who received transfusions and those who did not at every anemic threshold. Multivariable logistic regression was performed to evaluate the impact of blood transfusion on primary outcomes.

RESULTS

A total of 55,884 patients were included for analysis, of which 16.3% had severe anemia, 25.9% had moderate anemia, and 57.8% had normal Hgb. Anemia severity was associated with increased rates of MACE (9.8% vs. 8.3% vs. 5.2%, P < 0.0001) and MALE (32.2% vs. 24.8% vs. 18.6%, P < 0.0001). On univariate analysis, transfusion was consistently associated with increased rates of MACE and MALE at every anemic threshold (P < 0.0001 for all). Transfusion was also associated with increased rates of 30-day mortality at all anemic thresholds (P < 0.0001 for all) and reduced 1-year survival at all anemic thresholds (log-rank P < 0.0001 for all). On multivariable analysis for MACE, an interaction factor was observed between preoperative Hgb and transfusion status (P < 0.0001). At every anemic threshold, transfusion was independently associated with MACE (severe: odds ratio [OR] 2.4 [95% confidence interval [CI]: 2.0-2.9]; moderate: OR 2.8 [95% CI: 2.5-3.2]; normal: OR 4.5 [95% CI: 4.0-5.0]). On multivariable analysis for MALE, an interaction factor was also observed between preoperative Hgb and transfusion status (P < 0.0001). At every anemic threshold, transfusion was independently associated with MALE (severe: OR 2.1 [95% CI: 1.9-2.3]; moderate: OR 1.8 [95% CI: 1.7-2.0]; normal: OR 2.6 [95% CI: 2.4-2.8]).

CONCLUSIONS

Perioperative blood transfusion in patients undergoing infrainguinal LEB is independently associated with MACE and MALE in all patients with preoperative Hgb >7 g/dL. Despite the morbidities associated with anemia, these findings highlight that transfusion may not be the optimal treatment modality, particularly in patients with higher preoperative Hgb. Future research is needed to define the transfusion threshold in this population.

Transfusion and Anemia in Patients Undergoing Vascular Surgery

This cohort study examines the association between blood transfusion and major adverse cardiovascular events and mortality among people undergoing elective open vascular operations.

Tourniquet use for people with peripheral arterial disease undergoing major lower limb amputations

BACKGROUND

At least 7000 major lower limb amputations (MLLAs) are performed in the UK each year, 80% of which are due to peripheral arterial disease (PAD). Intraoperative blood loss can have a deleterious effect on patient outcomes, and its replacement with transfused blood is not without risk. Tourniquets can be used in lower limb surgical procedures to provide a bloodless surgical field, minimise intraoperative blood loss, and reduce perioperative blood transfusion requirements. Although their safety has been demonstrated in certain orthopaedic operations, their use among people with PAD undergoing MLLA remains controversial. Many clinicians are concerned about tourniquets potentially compromising perfusion of the stump and thereby impacting wound healing through direct tissue injury, damage to the arterial supply of the wound, or both.

OBJECTIVES

To assess the safety and effectiveness of tourniquet use in people undergoing MLLA for complications of PAD, specifically with regard to intraoperative blood loss, change in haemoglobin levels, transfusion rates, wound healing, need for revision surgery, and postoperative complications including mortality.

SEARCH METHODS

We searched the Cochrane Vascular Specialised Register, CENTRAL, MEDLINE, Embase, and CINAHL databases and World Health Organization International Clinical Trials Registry Platform and ClinicalTrials.gov trials registers from inception to 17 May 2022.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) comparing tourniquet use to no tourniquet use among people with PAD undergoing MLLA.

DATA COLLECTION AND ANALYSIS

We used standard Cochrane methods. Primary outcomes were intraoperative blood loss, fall in haemoglobin levels, and perioperative blood transfusion requirement. Secondary outcomes were primary wound-healing rates, stump revision rates, other postoperative complications defined as per Clavien-Dindo classification, and postoperative mortality at 30 days and at maximal follow-up. We used GRADE to assess the certainty of evidence for each outcome.

MAIN RESULTS

One RCT met our inclusion criteria, which was a prospective randomised blinded controlled trial conducted in Sheffield, UK in 2006. In total 64 participants undergoing transtibial amputation for non-reconstructable PAD were randomised to either tourniquet or no tourniquet to assess for intraoperative blood loss, fall in haemoglobin, transfusion requirement, wound healing, stump breakdown and revision. Ten participants were excluded postrandomisation (five from the tourniquet group and five from the no tourniquet group). The reported median volume of intraoperative blood loss was significantly less in the tourniquet group (255 mL (interquartile range (IQR) 150 to 572.5 mL))) compared to the control group (550 mL (IQR 255 to 1050 mL)) (P = 0.014). There was a significantly lower median drop in haemoglobin concentration in the tourniquet group (1.0 g/dL (IQR 0.6 to 2.4 g/dL)) compared to the control group (1.8 g/dL (IRQ 0 to 1.2 g/dL)) (P = 0.035). There was a significantly lower perioperative blood transfusion requirement in the tourniquet group (8 participants, 32%) compared to the control group (14 participants, 48%) (P = 0.047). There were no clear differences in wound breakdown, stump revision, primary wound healing at six weeks, postoperative complications (myocardial infarction, cardiac arrhythmias, pulmonary oedema), and death between groups. We assessed the one included study as at low risk of bias for sequence generation and blinding of outcome assessors; high risk of bias for incomplete outcome data and selective outcome reporting; and unclear risk of bias for allocation concealment, blinding of participants and personnel, and other sources of bias. We assessed the certainty of the evidence as low or very low due to risk of bias, small sample size, and the study being insufficiently powered for most outcomes.

AUTHORS' CONCLUSIONS

This review identified only one small historical RCT evaluating tourniquet use in MLLA. Tourniquets appeared to reduce intraoperative blood loss, drop in haemoglobin, and blood transfusion requirements following transtibial amputations for people with PAD. However, it is unclear whether tourniquets affect wound healing, stump revision rates, postoperative complications, or mortality. High-certainty evidence is required to inform clinical decision-making for the use of tourniquets in these patients.

Open repair of abdominal aortic aneurysms in patients with vascular Ehlers-Danlos syndrome

Vascular Ehlers-Danlos syndrome (VEDS) is rare, affecting an estimated 1 per 50,000 individuals, and is associated with abdominal aortic aneurysms (AAAs), among other arteriopathies. We present three patients with genetically confirmed VEDS who underwent successful open AAA surgical repair and demonstrate that elective open AAA repair with careful tissue manipulation is safe and feasible for patients with VEDS. These cases also demonstrate that the VEDS genotype is associated with the aortic tissue quality (genotype-surgical phenotype correlation), with the most friable tissue encountered in the patient with a large amino acid substitution and the least friable tissue in the patient with a null (haploinsufficiency) variant.

Intravenous Tranexamic Acid Reduces Post-Operative Bleeding and Blood Transfusion in Patients Undergoing Aortic Surgery: A PRISMA-Compliant Systematic Review and Meta-Analysis

Background

Tranexamic acid (TXA), an antifibrinolytic agent, has been demonstrated to reduce blood loss and transfusion requirements in both cardiac and non-cardiac surgery. However, the evidence regarding the efficacy of intravenous TXA in aortic surgery has been seldomly analyzed. Therefore, the current study was performed to address this question.

Methods

Searches of PubMed, EMBASE, OVID, Cochrane Library and CNKI were conducted comprehensively for randomized controlled trials (RCTs) comparing intravenous TXA versus no-TXA. Independently and in duplicate, we reviewed titles, abstracts and full-text articles, extracted data and evaluated bias risks. A random effect or fixed effect model was utilized to pool data.

Results

The database search yielded 4 RCTs involving 273 patients. Meta-analysis revealed that, there was a significant reduction in bleeding volume within the first 4 hours post-operatively [(weighted mean difference (WMD) = -74.33; 95% confidence interval (CI): -133.55 to -15.11; p = 0.01)], and the first 24 hours post-operatively [(WMD = -228.91; 95% CI: -352.60 to -105.23; p = 0.0003)], post-operative red blood cell (RBC) transfusion volume [(WMD = -420.00; 95% CI: -523.86 to -316.14; p < 0.00001)], fresh frozen plasma (FFP) transfusion volume [(WMD = -360.35; 95% CI: -394.80 to -325.89; p < 0.00001)] and platelet concentrate (PC) transfusion volume [(WMD = -1.27; 95% CI: -1.47 to -1.07; p < 0.0001)] following intravenous TXA administration. In addition, intravenous TXA administration significantly decreased the incidence of postoperative complications (53/451 (8.2%) vs. 75/421 (13.9%); odds ratio (OR) = 0.47; 95% CI: 0.30 to 0.75; p = 0.001), according to this present meta-analysis.

Conclusions

The current study preliminarily demonstrated that, TXA significantly reduced postoperative bleeding, blood transfusion requirements and postoperative complications among patients undergoing aortic surgery. More well-designed studies are warrant to confirm the efficacy and safety of intravenous TXA in patients undergoing aortic surgery.

Increased Regional Market Competition is Associated with a Lower Threshold for Revascularization in Asymptomatic Carotid Artery Stenosis

BACKGROUND

Revascularization practices with respect to asymptomatic carotid stenosis (ACAS) are known to vary widely among proceduralists. In addition, regional market competition has been previously shown to drive more aggressive practices in a number of surgical procedures. The aim of our study was to examine the association of regional market competition with revascularization thresholds for ACAS.

METHODS

All patients undergoing carotid revascularization in the Vascular Quality Initiative carotid endarterectomy and stenting databases (2016-2020) were included. High-grade carotid stenosis was defined as ≥80%. We calculated the Herfindahl-Hirschman Index (HHI; a measure of physician market competition) for each U.S region as defined by the U.S Department of Health and Human Services. Logistic regression was used to examine the association of degree of carotid stenosis at revascularization with HHI stratified by symptomatology, adjusting for age, sex, race, insurance, and revascularization modality.

RESULTS

Of 92,243 carotid interventions, 57,094 (61.9%) were performed for ACAS and 35,149 (38.1%) were performed for symptomatic carotid stenosis (SCAS). ACAS patients undergoing revascularization for moderate-grade stenosis were significantly less likely to be aspirin (85.6% vs. 86.3%), clopidogrel (41.3% vs. 45.1%), dual anti-platelet therapy (35.9% vs. 39.2%) and systemic anticoagulants (10.9 vs. 11.7%) compared to high-grade stenosis (all P < 0.05). Multivariable analysis demonstrated that decreased local market competition was independently associated with a lower odds of revascularization for moderate versus high-grade ACAS (odds ratio OR: 0.99 per 10 point increase in HHI, 95% confidence interval CI: 0.98-0.99). There was no association of local market competition with degree of carotid stenosis at time of revascularization among patients with SCAS (OR: 1.00 per 10 point increase in HHI, 95% CI: 0.99-1.00). Among ACAS patients, patients with moderate-grade stenosis had a higher odds ratio of in-hospital stroke or death compared to patients with high-grade stenosis (OR: 1.22, 95% CI 1.03-1.45). This association was not redemonstrated in the SCAS group (OR: 0.92, 95% CI: 0.80-1.06).

CONCLUSIONS

Increased local market competition is associated with a lower threshold for revascularization of ACAS. There is no association between regional market competition and revascularization threshold for SCAS. These findings, combined with the significantly increased risk of perioperative stroke/death among moderate-grade ACAS patients, suggest that competition among proceduralists may result in a higher tolerance for increased operative risk in patients who might otherwise be reasonable candidates for surveillance.

Association of Intraoperative and Perioperative Transfusions with Postoperative Cardiovascular Events and Mortality after Infrainguinal Revascularization

BACKGROUND

Patients undergoing open or endovascular infrainguinal revascularization are at elevated risk for postoperative cardiovascular complications due to high rates of comorbidities and the physiologic stress of surgery. Transfusions are known to be associated with adverse events, but knowledge of specific risks associated with transfusion timing, product type, and long-term outcomes while accounting for preoperative cardiovascular risk factors is not well understood in this population.

AIM

This study aimed to characterize the association of intraoperative and perioperative transfusion, anemia, and cardiovascular risk factors with cardiovascular events and mortality in patients undergoing infrainguinal revascularization.

METHODS

A single-center retrospective study was performed on 564 infrainguinal revascularization procedures, including both open (n=250) and endovascular (n=314) approaches (2016-2020). Comprehensive clinical data were collected including patient demographics, cardiovascular risk factors, preoperative hemoglobin, and detailed transfusion data. Multivariable logistic regression tested the association of transfusions with composite 30-day outcomes of cardiac complications (postoperative myocardial infarction [postop-MI], congestive heart failure [CHF], or dysrhythmia) and with major adverse cardiovascular events (MACE- postop-MI or death). Kaplan-Meier analysis and cox-proportional hazard modeling examined the association of transfusions, anemia, and cardiovascular risk factors with mortality up to 1 year.

RESULTS

Intraoperative transfusion was performed in 15% of cases and 13% underwent transfusion in the early postoperative period. Intraoperative transfusion was associated with higher Revised Cardiac Risk Index (RCRI), lower preoperative hemoglobin, increased blood loss and open procedures (all p<0.05). Within each RCRI score, intraoperative transfusion was associated with 2-4 fold increased MACE at 30 days. Intraoperative pRBC transfusion and early postoperative pRBC transfusion was associated with more than 2-fold adjusted odds of any cardiovascular complication and intraoperative transfusion was also associated with MACE (all p<0.05). Intraoperative transfusion was associated with mortality at one year on unadjusted analysis, but after adjustment for RCRI, age, and preoperative hemoglobin, only RCRI scores of 2 and 3+ and preoperatively hemoglobin remained significant risk factors for mortality.

CONCLUSIONS

Intraoperative and early perioperative transfusions are strongly associated with worse cardiovascular outcomes after infrainguinal revascularization. These findings may have prognostic value for further risk stratifying patients perioperatively at high risk for complications. However, prospective studies are needed to elucidate whether optimizing transfusion strategies mitigates these risks.

Significant Variation in Blood Transfusion Practice Persists Following Adolescent Idiopathic Scoliosis Surgery

STUDY DESIGN

Retrospective case control study.

OBJECTIVE

To review current transfusion practise following Adolescent Idiopathic Scoliosis (AIS) surgery and assess risks of complication from transfusion in this cohort.

SUMMARY OF BACKGROUND DATA

No study to date has investigated variation in blood transfusion practices across surgeons and hospitals following AIS surgery.

METHODS

Data were extracted from the Statewide Planning and Research Cooperative System. Using International Classification of Diseases (ICD-9) all patients with (ICD-9) code for AIS (737.30) ("idiopathic scoliosis") and underwent spinal fusion between 2000 and 2015 were included. Bivariate and mixed-effects logistic regression analyses were performed to assess patient, surgeon, and hospital factors associated with perioperative allogeneic red blood cell transfusion. Additional multivariable analyses examined the association between transfusion and infectious complications.

RESULTS

Of the 7689 patients who underwent AIS surgery, 21.1% received a perioperative blood transfusion. After controlling for patient factors, wide variation in risk-adjusted transfusion rates was present with a 10-fold difference in transfusion rates observed across surgeons (4.4%-46.1%) and hospitals (5.1%-50%). Patient factors did not explain any of the surgeon or hospital variation. Use of autologous blood transfusion, higher surgeon procedure volume, and greater surgeon years in practice were independently associated with lower odds of allogeneic blood transfusion (P < 0.001), and surgeon and hospital characteristics explained 45% of surgeon variation but only 2.4% of hospital variation. Allogeneic blood transfusion was independently associated with postoperative wound infection (OR = 1.87, 95% CI = 1.20-2.93), pneumonia (OR = 1.68, 95% CI = 1.26-2.44), and sepsis (OR = 2.42, 95% CI = 1.11-5.83).

CONCLUSION

Significant variation exists across both surgeons and hospitals in perioperative blood transfusion utilization following AIS surgery. Use of autologous blood transfusion and implementing institutional transfusion protocols may reduce unwarranted variation and potentially decrease infectious complication rates.Level of Evidence: 3.

Impact of Perioperative Blood Transfusion in Anemic Patients Undergoing Infra Inguinal Bypass

OBJECTIVE

Patients who present with lower extremity ischemia are frequently anemic and the optimal transfusion threshold for this cohort remains controversial. We sought to evaluate the impact of blood transfusion on postoperative major adverse cardiac events (MACE), including myocardial infarction, dysrhythmia, stroke, congestive heart failure, and 30-day mortality for these patients.

METHODS

All consecutive patients who underwent infra-inguinal bypass at our institution from 2011 to 2020 were included. Perioperative red blood cell transfusion was the primary exposure, and the primary outcome was MACE. Univariate and multivariable analyses were performed to assess the impact of patient and procedural variables, including red blood cell transfusion, stratified by hemoglobin (Hgb) nadir: <7, 7-8, and >8 g/dL.

RESULTS

Of the 287 patients reviewed for analysis, 146 (50.9%) had a perioperative transfusion (mean: 1.6 ± 3 units). Patients who received a transfusion had a mean nadir Hgb of 8.3 ± 1.0 g/dL, compared to 10.1 ± 1.7 g/dL without a transfusion. The overall incidence of MACE was 15.7% (45 of 287 patients). Univariate analysis demonstrated that MACE was associated with blood transfusion (P = 0.009), lower Hgb nadir (P = 0.02), and higher blood loss (P = 0.003). On multivariate analysis, transfusion was independently associated with MACE for patients with a Hgb nadir >8 g/dL (OR: 3.09; P = 0.006), but not for patients with Hgb nadir 7-8 g/dL (OR: 0.818; P = 0.77). Additionally, patients with MACE had significantly longer length of hospital stay than for patients without (13 vs. 7.7 days, P = 0.001).

CONCLUSIONS

For patients undergoing infra-inguinal bypass, receiving a red blood cell transfusion with a Hgb nadir >8 g/dL was associated with a 3-fold increase in MACE, with nearly twice the length of stay. For patients with a Hgb 7-8 g/dL, transfusion did not increase or reduce the incidence of MACE. These findings suggest no benefit of blood transfusion for patients with Hgb nadir >7 g/dL and harm for Hgb >8 g/dL, however causation cannot be proven due to the retrospective nature of the study and randomized studies are needed to confirm or refute these findings.

Quantifying the risk-adjusted hospital costs of postoperative complications after lower extremity bypass in patients with claudication

OBJECTIVE

Increasing evidence has shown that the risks associated with surgical revascularization for intermittent claudication outweigh the benefits. The aim of our study was to quantify the cost of care associated with perioperative complications after elective lower extremity bypass (LEB) in patients presenting with intermittent claudication.

METHODS

All patients undergoing first-time LEB for claudication in the Healthcare Database (2009-2015) were included. The primary outcome was in-hospital postoperative complications, including major adverse limb events (MALE), major adverse cardiac events (MACE), acute kidney injury, and wound complications. The overall crude hospital costs are reported, and a generalized linear model with log link and inverse Gaussian distribution was used to calculate the predicted hospital costs for specific complications.

RESULTS

Overall, 7154 patients had undergone elective LEB for claudication during the study period. The median age was 66 years (interquartile range, 59-73 years), 67.5% were male, and 75.3% were white. Two thirds of patients (61.2%) had Medicare insurance, followed by private insurance (26.9%), Medicaid (7.7%), and other insurance (4.2%). In-hospital complications occurred in 8.5% of patients, including acute kidney injury in 3.0%, MALE in 2.8%, wound complications in 2.3%, and MACE in 1.0%. The overall median crude hospital cost was $11,783 (interquartile range, $8911-$15,767) per patient. The incremental increase in cost associated with a postoperative complication was significant, ranging from $6183 (95% confidence interval, $4604-$7762) for MALE to $10,485 (95% confidence interval, $6529-$14,441) for MACE after risk adjustment.

CONCLUSIONS

Postoperative complications after elective LEB for claudication are not uncommon and increase the in-hospital costs by 46% to 78% depending on the complication. Surgical revascularization for claudication should be used sparingly in carefully selected patients.

Bleeding and thrombotic outcomes associated with postoperative use of direct oral anticoagulants after open peripheral artery bypass procedures

OBJECTIVE

Widespread adoption of direct oral anticoagulants (DOACs) for atrial fibrillation and venous thromboembolism treatment has resulted in peripheral bypass patients receiving therapeutic anticoagulation with DOACs postoperatively. This study was undertaken to evaluate patient outcomes after open peripheral bypass based on anticoagulation treatment.

METHODS

Postoperative treatment and outcomes of patients undergoing peripheral bypass operations between January 2012 and December 2017 from a statewide multicenter quality improvement registry were examined. Surgeons participating in the registry were surveyed on practice patterns regarding DOACs in bypass patients. Multivariate logistic regression was performed for 30-day transfusion outcomes, and multiple linear regression was performed for length of stay.

RESULTS

Among 9682 patients, 7685 patients received no anticoagulation, whereas 1379 received a vitamin K antagonist (VKA) and 618 received a DOAC postoperatively. Patients receiving anticoagulation compared with no anticoagulation had a higher body mass index and were more likely to have preoperative anemia, congestive heart failure, and atrial fibrillation (all P < .001). Compared with patients receiving VKAs, patients receiving DOACs were less likely to have chronic kidney disease (P = .002) and more likely to have atrial fibrillation (P < .001). The shortest length of stay was among patients receiving no anticoagulation (median, 5 days; interquartile range, 3-9 days; P < .001), followed by DOACs (median, 6 days; interquartile range 3-11 days; P < .001) and VKAs (median, 8 days; interquartile range, 5-13 days; P < .001). Compared with patients receiving VKAs postoperatively, there was no difference in readmission for anticoagulation complications, bypass thrombectomy or thrombolysis, major amputation, or graft patency at 1 year among patients receiving DOACs. On multivariate logistic regression, patients receiving a DOAC (odds ratio, 0.743; confidence interval, 0.59-0.94; P = .011) or no anticoagulation (odds ratio, 0.792; confidence interval, 0.69-0.91; P = .001) were less likely to require transfusion within 30 days than patients taking VKAs. Approximately 70% of the surveyed surgeons reported that they "sometimes" or "always" use DOACs instead of VKAs for protection of a high-risk bypass.

CONCLUSIONS

Among patients undergoing lower extremity surgical bypass, those receiving a DOAC postoperatively had a shorter length of stay and were less likely to receive a transfusion in 30 days without compromising graft patency and readmission for anticoagulation complications, thrombectomy, or thrombolysis or affecting amputation rate compared with those receiving a VKA. A majority of surgeons within the quality collaborative have adopted the use of DOACs after peripheral bypass, suggesting the need for a prospective trial evaluating DOAC safety and efficacy in patients requiring anticoagulation for high-risk bypass grafts.

Effect of postoperative haemoglobin variation on major cardiopulmonary complications in high cardiac risk patients undergoing anatomical lung resections

OBJECTIVES

Recent evidence shows that permissive anaemia strategies are safe in different surgical settings. However, effects of variations in haemoglobin (Hb) levels could have a negative impact in high-risk patients. We investigated the combined effect of postoperative Hb concentration and cardiac risk status on major cardiopulmonary complications after anatomical lung resections.

METHODS

We retrospectively analysed the records, collected in a prospective clinical database, of 154 consecutive patients undergoing anatomical lung resections at our institution (February 2017-February 2019). Hb levels were displayed as preoperative concentration, nadir Hb level before onset of complications and delta Hb (ΔHb). Cardiac risk was stratified according to the Thoracic Revised Cardiac Risk Index (ThRCRI). Univariable and multivariable logistic regression analyses were used to test the associations between patients, surgical variables and cardiopulmonary complications according to the European Society of Thoracic Surgeons definitions.

RESULTS

Cardiopulmonary complications occurred in 63 patients (17%). In the fully adjusted multivariable model, higher values of ΔHb were associated with increased risk of complications [odds ratio (OR) 1.07; P < 0.001], along with higher ThRCRI classes (classes A-B versus C-D: OR 0.09; P < 0.001). Interaction terms with transfusion were not statistically significant, indicating that the harmful effect of ΔHb was independent. According to receiver operating characteristic curve analysis, a ΔHb of 29 g/l was found to be the best cut-off value for predicting complications.

CONCLUSIONS

In our series, ΔHb, rather than nadir Hb, was associated with an increased risk of complications, particularly in patients with higher cardiac risk. Restrictive transfusion strategies should be carefully applied in patients undergoing lung resections and balanced according to individual clinical status.

Elective infrainguinal lower extremity bypass for claudication is associated with high postoperative intensive care utilization

BACKGROUND

The overall use of intensive care units (ICUs) in the United States has been steadily increasing and is associated with tremendous health care costs. We suspect that the burden of ICU utilization after elective infrainguinal lower extremity bypass (LEB) procedures is high, despite relatively low risks of complications in the immediate postoperative period. We sought to identify the burden of ICU utilization after elective LEB in patients with claudication.

METHODS

We queried the Premier Healthcare Database for all adult patients undergoing first recorded elective infrainguinal LEB for claudication from 2009 to 2015. Baseline characteristics and ICU utilization on postoperative day 0 (POD 0) were identified for each patient using Premier room and board chargemaster codes. A bivariate logistic regression was performed and postestimation concordance statistics were calculated to identify predictors of postoperative ICU vs regular surgical floor admission immediately after surgery.

RESULTS

There were 6010 patients who met the selection criteria, of whom 2772 (46.1%) were admitted to the ICU and 3238 (53.9%) to the regular surgical floor on POD 0. Whereas patient-level factors were responsible for minor differences found in postoperative admission to the ICU after elective LEB, hospital characteristics made up the majority of variation in admission practices. Specifically, patients undergoing elective infrainguinal LEB in rural, nonteaching, small hospitals and those in certain geographic regions were more likely to be admitted to the ICU than to the floor (all, P < .001). Patient-level factors were poorly predictive of admission to the ICU immediately postoperatively, with C statistics ranging from 0.50 to 0.53. In contrast, hospital-level factors had higher C statistics ranging from 0.51 to 0.66, with geographic location being the strongest predictor of post-LEB ICU admission. There were no significant differences in the incidence of postoperative wound complications, major adverse limb events, major adverse cardiac events, or in-hospital mortality between groups (all, P ≥ .32). The median total hospital cost was $2340 higher for ICU compared with floor admission ($13,273 [interquartile range, $10,136-$17,883] vs $10,927 [interquartile range, $8342-$14,523]; P < .001).

CONCLUSIONS

Nearly half of patients are admitted to an ICU directly after elective infrainguinal LEB for claudication. This practice is associated with significantly higher hospital cost and is predominantly influenced by hospital-level rather than by patient-level factors. Perioperative morbidity and mortality were similar regardless of postoperative disposition. To minimize ICU utilization, postoperative care intensity should be determined by clinical severity of the patient rather than by hospital routine.

Issues in the development of hemoglobin based oxygen carriers

Hemoglobin based oxygen carriers (HBOCs) have been developed as alternative oxygen transporting formulations for the acute treatment of anemia and ischemia. Efficacy has been demonstrated in a variety of preclinical models and selected human patients; however, a higher overall incidence of mortality and myocardial infarction in those dosed with HBOCs in later stage clinical trials has prevented widespread regulatory approval. Diagnosis of myocardial infarction is confounded by the fact that HBOCs interfere with troponin assays, as well as other clinical chemistry measurements. Analysis of data pertaining to potential toxicity mechanisms suggests that coronary vasoconstriction is an unlikely contributor, but promotion of intravascular thrombosis may occur by several mechanisms. In addition, fluid and anemia management in patients infused with HBOCs has been suboptimal. Elucidation of potential toxicity mechanisms, refinement of use protocols, and definition of improved patient inclusion/exclusion criteria remain active areas of inquiry in understanding the best manner in which to utilize HBOCs.

Transfusion Timing and Postoperative Myocardial Infarction and Death in Patients Undergoing Common Vascular Procedures

BACKGROUND

Perioperative allogenic blood transfusions, specifically packed red bloods cells (pRBC), after vascular surgery procedures are modifiable risk factors that are associated with increased cardiovascular events and 30-day mortality. The aim of this study is to evaluate the effect of transfusion timing (intraoperative vs. postoperative) on the rate of postoperative myocardial infarction (POMI) and death.

METHODS

Six surgical and endovascular modules within the Vascular Quality Initiative (VQI) from 2013 to 2017 were reviewed at a single institution. Transfusion data on elective and urgent cases were abstracted and all patients who underwent inpatient procedures had routine postoperative troponin/ECG testing. The primary endpoint was POMI utilizing the American Heart Association's third universal definition for myocardial infarction. These criteria include the detection of a rise/and or fall of cTnT with at least one value above the 99th percentile and with at least one of the following 1) symptoms of acute myocardial ischemia, 2) new ischemic ECG changes, 3) development of pathological Q waves, 4) imaging evidence of new loss of viable myocardium or new regional wall motion abnormality in a pattern consistent with ischemic etiology. The secondary endpoint was 30-day all-cause mortality. Multivariable logistic regression analysis was utilized to evaluate the risk of transfusions on POMI and death.

RESULTS

We identified 1,154 cases for analysis (299 abdominal aortic aneurysm [EVAR], 117 infrainguinal bypasses, 127 open abdominal aortic aneurysm [AAA], 41 suprainguinal bypasses, 168 thoracic endovascular aortic repair [TEVAR], and 402 peripheral vascular interventions). Overall, the POMI rate was 2% and mortality 1%. Rates of POMI differed by procedure type (P = 0.04), where infrainguinal bypass had the highest rate of POMI at 4%. Death rates did not vary by type of procedure (P = 0.89). Mean number of intraoperative pRBC and postoperative pRBC transfusion was higher for patients with POMI (intraop: 1.3 vs. 0.3, postop: 1.8 vs. 0.4, both P < 0.01) and death (intraop: 1.4 vs. 0.3, postop: 2.5 vs. 0.4, both P < 0.01). In addition, older age and coronary artery disease (CAD) were associated with POMI on univariate analysis. On multivariable analysis for POMI, CAD (odds ratio [OR] = 5.15, 95% confidence interval [CI] [2.00-13.24], P < 0.001), receiving both an intraoperative and postoperative transfusion (OR = 6.20, 95% CI [1.78-21.55], P < 0.01) as well as a postoperative transfusion only (OR = 5.70, 95% CI [1.81-17.94], P < 0.01) compared to no transfusion were associated with higher odds of POMI; however intraoperative transfusion only was not (OR = 3.42, 95% CI [0.88-13.31], P = 0.08). On multivariable analysis, increasing age of the patient was associated with higher odds of death (OR = 1.08, 95% CI [1.01-1.15], P = 0.02) and statin use was highly protective (OR = 0.27, 95% CI [0.10-0.74], P = 0.01), but any intraoperative or postoperative transfusion compared to no transfusion was not associated with death after adjustment.

CONCLUSIONS

In our series with routine postoperative troponin screening in the inpatient setting, the use of an isolated postoperative transfusion as well as cases requiring both an intraoperative and postoperative transfusion was associated with POMI. However, isolated intraoperative transfusion was not associated with POMI, and we did not identify an association of transfusion with 30-day mortality. These data suggest that the perioperative setting of transfusions is important in its impact on postoperative outcomes and needs to be accounted for when evaluating transfusion outcomes and indications.

Risk score for nonhome discharge after lower extremity bypass

OBJECTIVE

Patients undergoing lower extremity bypass (LEB) for peripheral artery disease require intensive health care resource utilization including rehabilitation and skilled nursing facilities. However, few studies have evaluated factors that lead to nonhome discharge (NHD) in this population of patients. This study sought to predict NHD by preoperative risk factors in patients undergoing LEB for peripheral artery disease using a novel risk score.

METHODS

The Vascular Study Group of New England database was queried for elective LEB for peripheral artery disease including claudication and critical limb ischemia from 2003 to 2017. Patients were excluded if the procedure was not elective, if they were not admitted from home, if they were bedridden, or if they died during the index admission. Only preoperative factors were considered in the analysis. The primary end point was NHD including rehabilitation and skilled nursing facilities. Data were split two-thirds for model derivation and one-third for validation. In the derivation cohort, bivariate analysis assessed the association of preoperative factors with NHD. A parsimonious manual stepwise binary logistic regression for NHD aimed at maximizing the C statistic while maintaining model simplicity was performed. A risk score was developed using the β coefficients and applied to the validation data set. The risk score performance was assessed using a C statistic and Hosmer-Lemeshow test for model fit.

RESULTS

There were 10,145 cases included with an overall NHD rate of 26.4% (n = 2676). Mean age was 66 years (range, 41-90 years). NHD patients were older (72 years vs 64 years; P < .01) and more frequently male (57.2% vs 42.8%; P < .01) and nonwhite (16.1% vs 9.9%; P < .01); they more frequently had tissue loss (54.2% vs 23.0%; P < .01), anemia (16.0% vs 5.3%; P < .01), severe cardiac comorbidity (21.8% vs 10.5%; P < .01), and insulin-dependent diabetes (33.3% vs 18.2%; P < .01). On multivariable analysis, factors associated with NHD included age, sex, nonwhite race, tissue loss, cardiac comorbidity, partial ambulatory deficit, and insulin-dependent diabetes. The C statistic was 0.78 in the derivation group and 0.79 in the validation group, with Hosmer-Lemeshow P > .999. The risk score ranged from 0 to 18, with a mean score of 4 (standard deviation ±3.5). The risk score was divided into low risk (0-4 points; n = 5272 [52%]; NHD = 10.1%]), moderate risk (5-9 points; n = 3663 [36.7%]; NHD = 36.7%), and high risk (≥10 points; n = 1210 [11.9%]; NHD = 66.1%).

CONCLUSIONS

This novel risk score was highly predictive for NHD after LEB for peripheral artery disease using only preoperative comorbidities. High-risk patients account for 12% of LEB but nearly a third of all patients requiring NHD. This risk score can be used preoperatively to determine high-risk patients for NHD, which may help improve preoperative counseling and hospital efficiency by allocating resources appropriately.