Does BICARBONATECorrect Coagulation Function impaired by Acidosis in Swine ? The Journal of TRAUMA injury, infection and Critical Care Wenjun S. Martini, Ph D, Michael A. Dubick, PhD … … ACCEPTED FOR PUBLICATION FEB 8,2006 PRESENTOR : 8901157 INT 黃曉禹
RESULT: • Reduced • fibrinogen • Platelet counts • Thrombin generation • clotting rapidity and MA • Prolonged • PT and PTT • After pH neutralization, no reversal Abstract Objective: The effects of acidosis and bicarbonate neutralization on coagulation function were investigated in vivo. CONCLUSION: coagulopathy induced by acidosis can’t be reversed • METHODS: • 12 pigs by infusing 0.2 mol/L HCl to pH 7.1. • LR to maintain a pH of 7.1 (A-LR, n= 6) • or 0.3 mol/L bicarbonate to a pH of 7.4 (A-Bi, n= 6). • 15 min after A-bi bicarbonate neutralization. • Coagulation function was assessed • by PT, PTT, thrombin generation,initial clot formation time (R), • clotting rapidity (α), and clot strength(MA).
Introduction ---why do this experiment ? • Acidosis in trauma patients • High mortality • Due to tissue hypoxia from massive hemorrhage and massive transfusion of stored blood.Disruption in coagulation (PT & PTT prolonged) • Study: ISS (Injury Severity Scores)=30 with 58 massively transfused patient 58% coagulopathy, if hypothermia & low SBP(<70mmHg)98%
Acidosis in trauma patients • Cause of disruption in coagulation • Hypothermia (reported) hypothermia reversal may correct hypothermia associated coagulation defects. • Thrombin – • detrimental effects of acidosis and hypothermia on thrombin generation kinetics in a swine model. • How about correct with pH neutralization??
Injury Severity Score • The Injury Severity Score (ISS) is an anatomical scoring system that provides an overall score for patients with multiple injuries. Each injury is assigned an Abbreviated Injury Scale (AIS) score and is allocated to one of six body regions (Head, Face, Chest, Abdomen, Extremities (including Pelvis), External). Only the highest AIS score in each body region is used. The 3 most severely injured body regions have their score squared and added together to produce the ISS score. • The ISS score takes values from 0 to 75. If an injury is assigned an AIS of 6 (unsurvivable injury), the ISS score is automatically assigned to 75. The ISS score is virtually the only anatomical scoring system in use and correlates slinearly with mortality, morbidity, hospital stay and other measures of severity.
The Abbreviated Injury Scale (AIS) is an anatomical scoring system first introduced in 1969. Since this time it has been revised and updated against survival so that it now provides a reasonably accurrate was of ranking the severity of injury. The latest incarnation of the AIS score is the 1990 revision. The AIS is monitored by a scaling committee of the Association for the Advancement of Automotive Medicine. Injuries are ranked on a scale of 1 to 6, with 1 being minor, 5 severe and 6 an unsurvivable injury. This represents the 'threat to life' associated with an injury and is not meant to represent a comprehensive measure of severity. The AIS is not an injury scale, in that the difference between AIS1 and AIS2 is not the same as that between AIS4 and AIS5. There are many similarities between the AIS scale and the Organ Injury Scales of the American Association for the Surgery of Trauma.
Materials and Methods • Protocol
Materials and Methods ~ 1 • Materials • 12 crossbred Yorkshire swine • 33 kg +/- 1 kg≈ • Overnight fast • Preaneshetized with glycopyrrolate (0.1 mg/kg) and Telazol (6 mg/kg) • Induced with 5% isoflurane in 100% oxygen and maintained 1%~3% isoflurane after intubation • Right femoral artery and the right external jugular vein were cannulated for blood sampling and fluid infusion • Arterial BT BP HR PH by XXXbrand
Materials and Methods ~ 2 • Induce metabolic acidosis • 0.2 mol/L HCL in LR solution • 0.07 mL/KG/min for initial 60ml solution • followed by increase to 0.14 mL/kg/min to reach pH 7.3, • then 0.21 mL/kg/min to reach pH 7.25, • then 0.28 mL/kg/min to reach pH 7.1 • Divide 2 group • A-Bi infusion of sodium bicarbonate at the rate of 0.28 mL/kg/min to neutralize arterial pH to 7.4. after 15 min with stable PH
Materials and Methods ~ 3 • Minimize coagulation effects from shear-induced platelet activation • 25mm single use catheter made from Tygon tubing • Withdrawn from the catheter and the first 3 mL of blood withdrawn • Hct, Platelet count, blood chemistry, PT, PTT, ACT by XXXbrand
Materials and Methods ~ 4 • Statistical analysis • Mixed model ANOVA with SAS statistical • Approved by the Institutional Animal Care and Use Committee • Guide for the Care and Use of Laboratory Animals, National Research Council, 1996
Results • HR, MAP, BE, Hct … … no significant change in acidosis induction • pH, Na, K, CA++, Cl-, HCO3- • Coagulation Profile • Fibrinogen, • platelet, • PT, PTT, ACT, • clotting rapidity, clot strength • thrombin generation
235±34 min 15 min after stabilized
Conclusion -1 • Infusion 0.2N HCL solution over nearly a 4 hr period • 35% depletion in fibrinogen concentration • 50% decrease in platelet count • 50% inhibition in thrombin generation • Blood clotting time was prolonged and clot formation and strength were impaired
Conclusion -2 • Lack of improvement while Infusion of bicarbonate neutralized pH to 7.4 • Based on previous observations: drug or resuscitation fluid may not be sufficient to restore normal coagulation function. • Specific clotting factor replacement may be necessary for the ultimate reversal of impaired coagulation associated with acidosis
Disscussion - OUTLINE • Possible mechanisms of coagulopathy in acidosis • PT, PTT, Thrombin time, fibrinogen, total protein (albumin and fibrinogen) • Comparison with other studies • Lactic acid vs hydrochloric acid • Hemodilutional effects
Disscussion ~ possible mechanism-1 • 35% depletion in fibrinogen concentration • Infusion 0.2N HCL solution over nearly a 4 hr period • Degradation or inhibit? • 2-4% fibrinogen synthesis rate per hr (in swine) degradation, irreversible • Without intervention, 10 hr for endogenous synthesis to replenish fibrinogen availability to normalize coagulation folowing acidosis even if there were no degradation
Total protein was only decreased about 10% - 15% during the infusion • Fibrinogen MW340,000 primarily confined in vascular pool, precursor in the coagulation process, T1/2= 3~4 day • Albumin MW 65,000 50% in vascular pool,, T1/2=16-18 days. Only 10% decrease in albumin concentration. • different protein different vulnerable level??
35% depletion in fibrinogen concentration significant degradation • Prospective study of 202 major torso trauma p’t Mckinley et al.. • Coagulopathy remained uncorrected throughout a 24 hr ICU period • Possible need for fibrinogen supplementation
Disscussion ~ possible mechanism-2 • 50% decrease in platelet count • Unable to explain, further studies is needed • 50% inhibition in thrombin generation • Acidosis depleted some coagulation substrates and inhibiting the thrombin generation burst • Bicarbonate prevented the return of normal thrombin generation • PT, PTT prolong • Unable to define specific sites due to too many enzymes , factors and cofactors
Disscussion ~Comparison with other studies • Coagulation & bicarbonate administration • Wong et al. • Bicarbonate increased from 12 mEq/L blood to 37 mEq/L • Thrombin time increased by 20% • In acidotic patients(n=4), a 50% to 100% prolongation in PT and PTT occurred. • Our report shows that bicarbonate interferes with fibrin monomer assembly into fibrin polymer and inhibits thrombin production. • MATCH!
Disscussion ~Lactic acid vs hydrochloric acid • Life threatening acidosis lactate • hemolysis and high mortality
Disscussion ~Hemodilutional effects • 1st portion: infusing 1.5L of 0.2N HCL in LR for 4 hrs • no changes observed in fibrinogen concentration, platelet counts and coagulation function in the group • 2nd Portion A-Bi 0.9 L of bicarbonate was infusing • Did not cause significant changes in plasma total protein, albumin and fibrinogen levels • PT, PTT?? • Present study: • At least 50% is required before a significant change in clotting parameters is observed • Estimate 10% - 15% in this hemodilution effect
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