does moderate hypothermia really carry less bleeding risk than deep hypothermia for circulatory...
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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
1
American Association for Thoracic Surgery Annual Meeting
April 28, 2015
Seattle, WA
Disclosures
• The authors have no conflicts of interest to report
2
Background
• Controversy exists over the optimal degree of hypothermia during surgery of aortic arch with circulatory arrest
3
Background
• Controversy exists over the optimal degree of hypothermia during surgery of aortic arch with circulatory arrest
4
• 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
5
• 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
6
• 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
7
Aortic Hemiarch Replacement
Deep HCAMinimum Systemic
Temperature ≤ 20°C
Moderate HCAMinimum Systemic
Temperature > 20°C
Methods
Aortic Hemiarch Replacement
Deep HCAMinimum Systemic
Temperature ≤ 20°C
Moderate HCAMinimum Systemic
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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Aortic Hemiarch Replacement
Deep HCAMinimum Systemic
Temperature ≤ 20°C
Moderate HCAMinimum Systemic
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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Aortic Hemiarch Replacement
Deep HCAMinimum Systemic
Temperature ≤ 20°C
Moderate HCAMinimum Systemic
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
12
Aortic Hemiarch Replacement
N=571
Deep HCAN=401 (70.2%)
Min. Sys. Temp.= 17.1°C
Moderate HCAN=170 (29.8%)
Min. Sys. Temp.= 24.0°C
Results
13
Results: Frequency of DHCA and MHCA
Through 8/2014
14
Aortic Hemiarch Replacement
Deep HCAN=401
Min. Sys. Temp.= 17.1°C
Moderate HCAN=170
Min. Sys. Temp.= 24.0°C
Methods
Deep HCAN=155
Min. Sys. Temp.= 17.0°C
Moderate HCAN=155
Min. Sys. Temp.= 24.0°C
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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VariableDeep HCA(N=155)
Moderate HCA(N=155) P-value
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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VariableDeep HCA(N=155)
Moderate HCA(N=155) P-value
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
18
VariableDeep HCA(N=155)
Moderate HCA(N=155) P-value
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
19
Outcome Deep HCA(N=155)
Moderate HCA(N=155) P-value
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
Results: Bleeding-Related Outcomes
20
Outcome Deep HCA(N=155)
Moderate HCA(N=155) P-value
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
Results: Bleeding-Related Outcomes
21
Outcome Deep HCA(N=155)
Moderate HCA(N=155) P-value
Operative Day Transfusion
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
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
Results: Bleeding-Related Outcomes
22
Outcome Deep HCA(N=155)
Moderate HCA(N=155) P-value
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
Results: Bleeding-Related Outcomes
23
Outcome Deep HCA(N=155)
Moderate HCA(N=155) P-value
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
Results: Bleeding-Related Outcomes
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Outcome Deep HCA(N=155)
Moderate HCA(N=155) P-value
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
Results: Bleeding-Related Outcomes
25
OutcomeDeep HCA(N=155)
Moderate HCA(N=155) P-value
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
26
VariableDeep HCA(N=155)
Moderate HCA(N=155) P-value
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
Results: Secondary Outcomes - Intraoperative
27
VariableDeep HCA(N=155)
Moderate HCA(N=155) P-value
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
Results: Secondary Outcomes - Intraoperative
28
VariableDeep HCA(N=155)
Moderate HCA(N=155) P-value
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
Results: Secondary Outcomes - Clinical
29
OutcomeDeep HCA(N=155)
Moderate HCA(N=155) P-value
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
Results: Secondary Outcomes - Clinical
30
OutcomeDeep HCA(N=155)
Moderate HCA(N=155) P-value
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
Results: Secondary Outcomes - Clinical
31
OutcomeDeep HCA(N=155)
Moderate HCA(N=155) P-value
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
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
33
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
34
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