Does Moderate Hypothermia Really Carry Less Bleeding Risk than Deep Hypothermia For Circulatory...

Does Moderate Hypothermia Really Carry Less Bleeding Risk than Deep Hypothermia For Circulatory

Arrest? A Propensity-Matched Comparison in Hemiarch Replacement

Jeffrey E. Keenan, MD; Hanghang Wang, MD; Brian C. Gulack, MD;

Asvin M. Ganapathi, MD; Nicholas D. Andersen MD; Brian R. Englum, MD; Yamini Krishnamurthy, MSIV; Jerrold H. Levy, MD;

Ian J. Welsby, MD; G. Chad Hughes, MD

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American Association for Thoracic Surgery Annual Meeting

April 28, 2015

Seattle, WA

Disclosures

• The authors have no conflicts of interest to report

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Background

• Controversy exists over the optimal degree of hypothermia during surgery of aortic arch with circulatory arrest

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Background

• Controversy exists over the optimal degree of hypothermia during surgery of aortic arch with circulatory arrest

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• Greater suppression of metabolic activity

• May offer better organ

protection, particularly for the brain and spinal cord which are highly susceptible to hypoxic injury

• May provide adequate visceral and cerebral protection in conjunction with regional perfusion to the brain during systemic arrest

• Potentially mitigates hypothermia-related complications

Deep Hypothermia Moderate Hypothermia

Vs.

Background

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• Coagulopathic bleeding during aortic arch surgery– Multifactorial

• Hypothermia-related platelet dysfunction• Coagulation factor consumption during prolonged CPB

• Theoretically, milder degrees of hypothermia may reduce coagulopathy and bleeding-related complications– Lack of empirical data to support this claim

Objective

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• To determine whether moderate hypothermic circulatory arrest (MHCA) compared to deep hypothermic circulatory arrest (DHCA) reduced the risk of bleeding and the blood product transfusion in patients undergoing aortic hemiarch replacement

Methods

• Duke University Medical Center Aortic Surgery Database– Prospectively maintained– Contains >1500 procedures from 2005-present

• Study population– Patients who underwent replacement of aortic root or

supracoronary ascending aorta (+/- valve) with concomitant hemiarch replacement from 7/2005 to 8/2014

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Aortic Hemiarch Replacement

Deep HCAMinimum Systemic

Temperature ≤ 20°C

Moderate HCAMinimum Systemic

Temperature > 20°C

Methods





Temperature > 20°C

Methods

Recent expert consensus guidelines on deep vs. moderate degrees of hypothermia in aortic arch surgery:Yan et. al Annals of Cardiothoracic Surgery 2013

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Temperature > 20°C

Methods

1:1 Propensity Matchage, gender, race, BMI, hypertension, tobacco use, diabetes, coronary artery disease,

congestive heart failure, history of stroke, chronic renal insufficiency (baseline creatinine >1.5), connective tissue disease, ASA class, bicuspid aortic valve, acute

type A aortic dissection, chronic type A aortic dissection, preoperative malperfusion or shock, aortic rupture, procedural status, concomitant root replacement, redo

sternotomy, and preoperative hematologic labs

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Temperature > 20°C

Methods

Study Outcomes• Primary (bleeding-related): operative day transfusion,

reoperation for bleeding, cell saver transfusion, rFVIIa utilization, 12 hour postoperative chest tube output, post-op labs

• Secondary: mortality, organ-specific morbidity, intraoperative outcomes

Propensity Match

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N=571

Deep HCAN=401 (70.2%)

Min. Sys. Temp.= 17.1°C

Moderate HCAN=170 (29.8%)


Results

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Results: Frequency of DHCA and MHCA

Through 8/2014

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Deep HCAN=401


Moderate HCAN=170


Methods

Deep HCAN=155


Moderate HCAN=155


Propensity Matching

Results: Matched Baseline Characteristics

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VariableDeep HCA(N=155)

Moderate HCA(N=155) P-value

Age 60 (47, 69) 58 (51.5, 68) 0.82

Female 50 (32.3%) 49 (31.6%) 0.99

White Race 108 (69.7%) 114 (73.5%) 0.53

Body Mass Index 28.4 (25.0, 31.8) 28.4 (25.3, 32.3) 0.66

Hypertension 124 (80.0%) 123 (79.4%) 0.99

Hyperlipidemia 78 (50.3%) 86 (55.5%) 0.43Smoker 62 (40.0%) 55 (35.5%) 0.48Diabetes 12 (7.7%) 13 (8.4%) 0.99Coronary Artery Disease 38 (24.5%) 38 (24.5%) 0.99History of MI 10 (6.5%) 16 (10.3%) 0.31CHF (NYHA ≥2) 52 (33.5%) 43 (27.7%) 0.32History of Stroke/TIA 11 (7.1%) 12 (7.7%) 0.99COPD 13 (8.4%) 17 (11.0%) 0.57Chronic Kidney Disease 24 (15.5%) 23 (14.8%) 0.99Peripheral Artery Disease 6 (3.9%) 11 (7.1%) 0.32

Results: Matched Aortic Characteristics

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Connective Tissue Disease 4 (2.6%) 5 (3.2%) 0.99

Bicuspid Aortic Valve 58 (37.4%) 56 (36.1%) 0.91

Ascending Aortic Dissection 45 (29.0%) 48 (31.0%) 0.80

Acute 35 (77.8%) 42 (87.5%) 0.28

Chronic 10 (22.2%) 7 (14.6%) 0.42

Acute Dissection with Malperfusion or Shock

10 (6.5%) 12 (7.7%) 0.83

Max Aortic Diameter 5.4 (5.0, 5.8) 5.3 (5.0, 5.8) 0.53Aortic Rupture 8 (5.2%) 9 (5.8%) 0.99

Results: Matched Procedural Characteristics

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ASA class 0.28

2 18 (11.6%) 27 (17.4%)

3 94 (60.6%) 83 (53.5%)

4 43 (27.7%) 45 (29.0%)

Procedural Status 0.45

Elective 111 (71.6%) 104 (67.1%) Urgent 16 (10.3%) 14 (9.0%) Emergent 28 (18.1%) 37 (23.9%) Previous Aortic Surgery 25 (16.1%) 22 (14.2%) 0.75Redo Sternotomy 28 (18.1%) 25 (16.1%) 0.76Root Replacement 49 (31.6%) 49 (31.6%) 0.99

Results: Preoperative Hematologic Labs

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Hemoglobin (g/dL) 13.3 (11.9, 14.7) 13.5 (12.1, 14.7) 0.28

INR 1.0 (1.0, 1.1) 1.0 (1.0, 1.1) 0.47

Platelets (109/L) 204 (170.5, 249) 197 (165, 242) 0.26

PTT 30.1 (27.8, 32.7) 30.5 (28.0, 32.7) 0.70

Creatinine 1.0 (0.9, 1.2) 1.0 (0.9, 1.2) 0.58

Results: Bleeding-Related Outcomes

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Outcome Deep HCA(N=155)


Operative Day Transfusion

PRBC (units) 2 (0, 4) 2 (0, 4) 0.86

Plasma (units) 6 (4, 8) 4 (4, 8) 0.1

Platelets (units) 2 (1, 3) 2 (1.5, 3) 0.45

Cryoprecipitate (units) 0 (0, 1) 0 (0, 1) 0.02 ≥1 unit Cryoprecipitate 60 (36.1%) 70 (44.5%) 0.003

Cell Saver (mL) 500 (250, 744) 472 (250, 700) < 0.001Intraoperative rFVIIa 35 (22.6%) 52 (33.5%) 0.04Postoperative rFVIIa 8 (5.2%) 5 (3.2%) 0.5712hr Chest Tube Output (mL) 405 (262, 740) 360 (230, 633) < 0.001Reoperation for Bleeding 5 (3.2%) 5 (3.2%) 1


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PRBC (units) 2 (0, 4) 2 (0, 4) 0.86

Plasma (units) 6 (4, 8) 4 (4, 8) 0.1

Platelets (units) 2 (1, 3) 2 (1.5, 3) 0.45




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PRBC (units) 2 (0, 4) 2 (0, 4) 0.86

Plasma (units) 6 (4, 8) 4 (4, 8) 0.10

Platelets (units) 2 (1, 3) 2 (1.5, 3) 0.45




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PRBC (units) 2 (0, 4) 2 (0, 4) 0.86

Plasma (units) 6 (4, 8) 4 (4, 8) 0.1

Platelets (units) 2 (1, 3) 2 (1.5, 3) 0.45




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PRBC (units) 2 (0, 4) 2 (0, 4) 0.86

Plasma (units) 6 (4, 8) 4 (4, 8) 0.1

Platelets (units) 2 (1, 3) 2 (1.5, 3) 0.45




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PRBC (units) 2 (0, 4) 2 (0, 4) 0.86

Plasma (units) 6 (4, 8) 4 (4, 8) 0.1

Platelets (units) 2 (1, 3) 2 (1.5, 3) 0.45




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OutcomeDeep HCA(N=155)


Hemoglobin (g/dL) 9.9 (9.25, 10.5) 10.0 (9.4, 10.55) 0.23

Platelets (109/L) 140 (115, 176.5) 147 (127, 173) 0.08

INR 1.1 (1.0, 1.2) 1.1 (0.9, 1.2) 0.03

INR ≥ 1.2 72 (46.8%) 53 (35.6%) 0.048

PTT (sec) 28.7 (25.95, 37.0) 28.6 (21.3, 31.4) 0.26

Results: Secondary Outcomes - Intraoperative

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Cardiopulmonary Bypass Time 204 (182, 232) 182 (150, 215) < 0.001Crossclamp Time 127 (107, 154) 117 (95, 147) 0.07Circulatory Arrest Time 17 (15, 22) 16.5 (13, 20) 0.04Operative Time 329 (297, 378) 320 (281, 367) 0.27


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Results: Secondary Outcomes - Clinical

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30-Day/Inpatient Mortality 3 (1.9%) 5 (3.2%) 0.72

AKI ( Creatinine > 2.0 & 2x baseline) 11 (7.1%) 16 (10.3%) 0.42

New Onset Dialysis 1 (0.6%) 7 (4.5%) 0.07Stroke 2 (1.3%) 1 (0.6%) 0.99Transient Ischemic Attack 1 (0.6%) 0 0.99Prolonged Ventilation (>24 hours) 19 (12.3%) 13 (8.4%) 0.3530-Day Readmission 20 (12.9%) 16 (10.3%) 0.60Discharge to location other than home 3 (1.9%) 3 (1.9%) 0.99


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Summary

• MHCA compared to DHCA may have led to a slight statistical decrease in perioperative bleeding (decreased cell saver transfusion, post-operative output)

• However, this did not translate to clinically apparent benefit such as reduced rate of transfusion or reoperation for bleeding

• Mortality and morbidity did not appear to differ between patients managed with MHCA vs. DHCA

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Limitations

• Potential for unobserved confounding

• Non-standardization of transfusion and surgical practice over the entire course of the study– Institution of transfusion (~2010) algorithm may account for

increased cryoprecipitate and rFVIIa use in MHCA patients

• Lack of functional coagulation assessments

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Conclusions

• MHCA compared to DHCA did not appear to lead to a clinically significant reduction in bleeding or blood product transfusion – This draws into question whether reduced severity of bleeding

should be used to justify use of MHCA over DHCA

• Comparable mortality and morbidity between the DHCA and MHCA confirms clinical equipoise and supports the need for prospective study to better elucidate the optimal degree of hypothermia during aortic reconstruction with circulatory arrest

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