Acid-Base Acid-Base Abnormalities DuringAbnormalities During

Cardiopulmonary Cardiopulmonary Resuscitation (CPR)Resuscitation (CPR)

Anakapong Phunmanee M.D. Associated Professor

Faculty of Medicine, Khon Kaen University

Cardiac Output During Cardiac Output During CPRCPR

0

1

2

3

4

5

6

Normal CO CPR

Del Guercio LRM, et al. Circulation 1965; Del Guercio LRM, et al. Circulation 1965; 32:I171-180.32:I171-180.

Normal CO = 2.5-3.6 L/m2(BSA)/minNormal CO = 2.5-3.6 L/m2(BSA)/min

Metabolism During CPRMetabolism During CPRAerobic Metabolism

Anaerobic Metabolism

Progressive increase CO2 in cells

PCO2 90-475 mmHgPCO2 >475 EMD

ConfusionFollowing CPR

MacGregor DC,et al. J Thorac Cardiovasc MacGregor DC,et al. J Thorac Cardiovasc Surg 1974.Surg 1974. Niemann JT,et al. Ann Emerg Med 1984.Niemann JT,et al. Ann Emerg Med 1984.

Intamyocardial pH and cardiac venous blood

Planta M, et al. Circulation 1989;80:684-92.

CO2 transport during CPR

Planta M, et al. Circulation 1989;80:684-92.

Arterial pH and PCO2 different

Arterial vs Veneous blood Arterial vs Veneous blood during CPRduring CPR

CO2

CO2

CO2

CO2 Vein

Arterial blood

venous blood

pH less acidotic

pH acidoticpH 7.1PvCO2 74

Venous paradox

Weil MH,et al. N Eng J Med 1986; Weil MH,et al. N Eng J Med 1986; 314:153-156.314:153-156.

Myocardial K uptake during experimental CPR

Von Planta M, et al. Crit Care Med 1989;17:895-99.

Arterial blood during Arterial blood during CPRCPR

Severe Acidotic arterial blood

Inadequate V/Q

Improved mechanical technique

HyperventilationCorrect intubation

Alternate method for circulationOpen-chest compression

Venoarterial bypassOrnato JP, et al. Am J Emerg Med Ornato JP, et al. Am J Emerg Med

1985;3:498-502.1985;3:498-502.

Composition and physiochemical of buffer agents

AnorganicNaHCO3Na2CO3

OrganicTHAM

(Tris-hydroxymethyl amino-methane)

MixturesCABICARB

(NaHCO3, Na2CO3)

TRIBONATE (NaHCO3, THAM, Phosphate, Acetate)

NaHCO3 pH 8.0Na2CO3 pH 11.7

THAM pH 8.4

CARBICARB pH 9.6

TRIBONATE pH 8.1

NaHCO3

H + HCO3 <-- -->H2CO3 <-- --> H2O2 +CO2

Na 1000 , Osm 2000 mOsm/l

Na2CO3

Na2CO3+ CO2 +H2O <----> 2HCO3 + 2Na

HCO3 + H

Na 1000 , Osm 1500 mOsm/l

CARBIBARB

NaHCO3 + Na2CO3

Na 1000 , Osm 1667 mOsm/l

Buffering agents and CPR

Kette F, et al. Clin Res 1988;36:10.

Myocardial pH

Comparison of coronary perfusion pressure

Shijie Sun Pharmacology and Experimental Therapneutics;1999:773-777.

NaHCO3 administration NaHCO3 administration duringduringCPR: A MistakeCPR: A Mistake

NaHCO3(PCO2 260-280)

CO2 HCO3 Na

Falling Intracellular pH

Hyperosmolarity Na overload

DETRIMENDETRIMENTT

BENEFIBENEFITT

95%CI

CPR OUTCOME AFTER NaHCO3

Von Planta M. Circulatoire Aigue. 1994.

NaHCO3 administration NaHCO3 administration during CPRduring CPR

Should not be used until other Should not be used until other proven interventions (ET tube, proven interventions (ET tube, defibrillation, cardiac defibrillation, cardiac compression, adrenaline)compression, adrenaline)

Estimated that this interventions Estimated that this interventions required at least 10 min.required at least 10 min.

Guideline for NaHCO3 Guideline for NaHCO3 administration during CPRadministration during CPR

Known preexisting metabolic Known preexisting metabolic acidosis with or without acidosis with or without hyperkalemiahyperkalemia

Known hypercalcemiaKnown hypercalcemia DoasageDoasage

1 mEQ/kg then no more than half for 1 mEQ/kg then no more than half for subsequent dosesubsequent dose

No more frequently than every 10 minNo more frequently than every 10 min Postresuscitation phase, guideed Postresuscitation phase, guideed

by arterial blood gasby arterial blood gas

Alternate buffer agents Alternate buffer agents during CPRduring CPR

THAM (tromethamine), potent amine THAM (tromethamine), potent amine bufferbuffer

DCA (Dichloroacetate), stimulating DCA (Dichloroacetate), stimulating pyruvate dehydrogenase (oxidative pyruvate dehydrogenase (oxidative enzyme in step of lactate to pyruvate)enzyme in step of lactate to pyruvate)

However, no alternate buffer However, no alternate buffer agents improve survival during agents improve survival during CPRCPR

Lee WH, et al. Am Surg 1962. Lee WH, et al. Am Surg 1962. Stacpoole PW, et al. N Engl J Med Stacpoole PW, et al. N Engl J Med

1983.1983.

Buffering agents and Buffering agents and survivalsurvival

Shijie Sun Pharmacology and Experimental Therapneutics;1999:773-777.

CapnographyCapnography

Normal respiration, circulation, the PETCO2 about 4-5 % (1% Normal respiration, circulation, the PETCO2 about 4-5 % (1% approximately 7 mmHg)approximately 7 mmHg)

CapnographyCapnography

Minute Ventilation

PETCO2

PETCO2 & PETCO2 & HyperventilationHyperventilation

Normal CO; PETCO2 ~ PCO2

PETCO2

PETCO2 & Cardiac PETCO2 & Cardiac OutputOutput

Cardiac Output

PETCO2 ¼ of normal

ROSC Increase PETCO2

Common causes of low Common causes of low PETCO2PETCO2(< 2%)(< 2%)

Inadequate ventilationInadequate ventilation Esophageal intubationEsophageal intubation Airway obstructionAirway obstruction

V/Q mismatchV/Q mismatch Pulmonary emboliPulmonary emboli

Inadequate blood flowInadequate blood flow Inadquate chest compressionInadquate chest compression Hypovolumia Hypovolumia Tension pneumothoraxTension pneumothorax Pericardial tamponadePericardial tamponade

Decrease metabolic productionDecrease metabolic production eq. eq. hypothermiahypothermia

End-tidal CO2 End-tidal CO2 concentration (PETCO2)concentration (PETCO2)

Clinical indicationClinical indication Confirm ET tube placement (sen, spec, Confirm ET tube placement (sen, spec,

100, 90%)100, 90%) Esophageal intubation results in Esophageal intubation results in

PETCO2 < 0.5%PETCO2 < 0.5% Guide hemodynamic status: inadequate Guide hemodynamic status: inadequate

chest compression PETCO2 < 1%chest compression PETCO2 < 1% Prognostic value: PETCO2 20 min after Prognostic value: PETCO2 20 min after

CPR < 10 mmHg accurately predicts CPR < 10 mmHg accurately predicts deathdeath

Acid-Base Abnormalities Acid-Base Abnormalities During CPR: ConclusionDuring CPR: Conclusion

Intracellular acidosis plays an Intracellular acidosis plays an important roleimportant role

The treatment is properly The treatment is properly performed CPR and airway performed CPR and airway managementmanagement

Pharmacologic buffers have no Pharmacologic buffers have no benefit and potentially riskbenefit and potentially risk

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