Acid Base Balance And Disturbance

Acid-base balance and disturbance Yu-Hong Jia, Ph.D Department of pathophysiology Dalian medical university

[object Object],[object Object],[object Object],Acid-base balance is important for metabolic activity of the body

Changes in excitability of nerve and muscle cells ,[object Object],[object Object],[object Object],[object Object]

Alteration of enzymatic activity ,[object Object],pH change

Alteration of K + levels Acid-base state of ECF influence: K + distribution in ECF and ICF Renal excretion of K +

Acid-base balance: the process maintaining pH value in a normal range ﹥ Acid-base disturbance or imbalance 7 8 6 5 4 3 2 1 0 9 10 11 12 13 14 acid base pH ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Acid-base disturbances ,[object Object],[object Object]

(Ⅰ). Concept of acids and bases ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

[object Object],[object Object],[object Object],[object Object]

(Ⅱ). Generation of acids and bases ,[object Object],[object Object],[object Object],[object Object],CO 2 H 2 O H + +HCO 3 - H 2 CO 3 + Lung: 300L 15mol Respiratory regulation of acid-base balance

[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],Kidney: Renal regulation of acid-base balance

[object Object],[object Object],[object Object]

( Ⅲ ). Regulation of acid-base balance ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Henderson-Hasselbalch equation ,[object Object],= pK α + lg = 6.1 + lg = 6.1 + lg = 7.4 dCO 2 = α × PaCO 2 dissolubility pK α = 6.1 α = 0.03 [HCO 3 - ]=24mmol/L PaCO 2 =40mmHg [HCO 3 - ] [H 2 CO 3 ] [HCO 3 - ] α · PaCO 2 24 0.03 × 40 20 1

[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],1. Blood buffering H + OH - H + H + OH - OH - Buffer

Bicarbonate buffer system (HCO 3 - /H 2 CO 3 ) ,[object Object],[object Object],[object Object],[object Object],[object Object],CO 2 H 2 O H + + HCO 3 - H 2 CO 3 + lung kidney ventilation H + secretion HCO 3 - reabsorption

PROTEIN BUFFER SYSTEM ,[object Object],[object Object],- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - + + + + + + + + + + + + + + + + + + + + + + + + +

Blood buffering ,[object Object],[object Object],[object Object]

2. Respiratory regulation ,[object Object],pH = pK α + lg = pK α + lg [HCO 3 - ] [H 2 CO 3 ] [HCO 3 - ] α · PaCO 2

Regulation of alveolar ventilation (V A ) ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],CO 2 narcosis

How does alteration of alveolar ventilation regulate pH value? ,[object Object],↓ pH = pK α + lg [HCO 3 - ] [H 2 CO 3 ] ↓ ↑

3. Renal regulation ,[object Object],pH = pK α + lg = pK α + lg [HCO 3 - ] [H 2 CO 3 ] [HCO 3 - ] α · PaCO 2

(1). Bicarbonate conservation ,[object Object],[object Object]

Reclamation of HCO 3 - or secretion of H + in proximal tubules CA Na + (filtered) (CA)

ATPase + HPO 4 2- H 2 PO 4 - Cl - (filtered) Regeneration of HCO 3 - or secretion of H + in distal tubules and collecting duct Urine acidification Urine pH: 4.5-4.8 ～ 8.0

[object Object],[object Object],[object Object],[object Object],Bicarbonate conservation

(2). H + elimination (acid excretion) ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Glutamine NH 3 α -Ketoglutarate acid H 2 CO 3 H + HCO 3 - Na + glutaminase + NH 4 + Na + NH 4 + HCO 3 - H 2 CO 3 H + NH 3 H + CO 2 +H 2 O CA ATPase NH 3 Cl - Proximal tubular cells Distal and collecting tubular cell Tubular lumen Ammonia secretion in proximal tubule and distal and collecting tubule capillary

How does the renal regulation maintain the constant pH value? ,[object Object],↑ ↑ pH = pK α + lg [HCO 3 - ] [H 2 CO 3 ] ↓

4. ion exchange between intra- and extracellular compartment & intracellular buffering ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

(Ⅳ). Laboratory tests ,[object Object],[object Object],[object Object],[object Object],pH = pK α + lg = pK α + lg [HCO 3 - ] [H 2 CO 3 ] [HCO 3 - ] α · PaCO 2

[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

2. PaCO 2 (partial pressure of CO 2 in arterial blood) ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],pH = pK α + lg = pK α + lg — Respiratory parameter [CO 2 ] dissolved +H 2 O H 2 CO 3 [HCO 3 - ] [H 2 CO 3 ] [HCO 3 - ] α · PaCO 2

3. [HCO 3 - ] ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],— metabolic parameter

4. Anion gap (AG) ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],Na + Cl - HCO 3 - UA UC Measured cation Measured anion

Ⅱ . Simple acid-base disorders

[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],Classification of simple acid-base disorders [HCO 3 - ] Primarily ↓, from 20 to 10 If [H 2 CO 3 ] secondarily↓, from 1 to 0.5-> pH normal If [H 2 CO 3 ] secondarily ↓, from 1 to 0.8-> pH↓ Metabolic parameter pH = pK α + lg [HCO 3 - ] [H 2 CO 3 ] = 6.1 + lg [HCO 3 - ] α · PaCO 2 = 6.1+ lg 20 1 =7.4 respiratory parameter

(Ⅰ). Metabolic acidosis ,[object Object],[object Object],H 2 CO 3 HCO 3 - 1 10 : = 7.4 H 2 CO 3 HCO 3 - 1 20 : = 7.4

2. Primary causes ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

(1). Direct excessive loss of HCO 3 - ,[object Object],[object Object],[object Object],[object Object],Na +

(2). Excessive production of nonvolatile acid ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

(3). Excessive intake of nonvolatile acids ,[object Object],[object Object],[object Object]

(4). Decreased renal excretion of acid ,[object Object],[object Object],[object Object],Cl - +HPO 4 2- H 2 PO 4 - filter

3. Classification of metabolic acidosis ,[object Object],[object Object],[object Object],[object Object],[object Object]

4. compensation ,[object Object],[object Object],[object Object]

[object Object],[object Object]

[object Object],[object Object],[object Object],[object Object],[object Object],↑ [HCO 3 - ], and [HCO 3 - ] /[H 2 CO 3 ] near 20/1 pH is near to normal

METABOLIC ACIDOSIS - metabolic balance before onset of acidosis - pH 7.4 ,[object Object],[object Object],- HCO 3 - decreases because of excess presence of ketones, chloride or organic ions - body’s compensation - hyperactive breathing to “ blow off ” CO 2 - kidneys conserve HCO 3 - and eliminate H + ions in acidic urine - therapy required to restore metabolic balance - lactate solution used in therapy is converted to bicarbonate ions in the liver 0.5 10

5. Alteration of metabolism and function ,[object Object],[object Object]

(1). Cardiovascular system ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Excitation-Contraction Coupling × × ×

(2). CNS ,[object Object],[object Object],[object Object],[object Object],－ depression

(Ⅱ). Respiratory acidosis ,[object Object],[object Object],H 2 CO 3 HCO 3 - 2 20 : H 2 CO 3 HCO 3 - 1 20 : =7.4 =7.4

2. Primary causes ,[object Object],[object Object]

(1). Decreased alveolar ventilation ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],Physiological processes involving alveolar ventilation: Respiratory center Respiratory muscle Thoracic cage Lung Respiratory tract

(2). Increased CO 2 inhalation ,[object Object],[object Object]

3. Classification ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

4. compensation ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

[object Object],[object Object],[object Object],[object Object],Carbonic anhydrase When PaCO 2 is 60mmHg, then PaCO 2 increase 20mmHg, and through compensation [HCO 3 - ] increase 2mmol/L, pH=6.1+lg(24+2)/0.03×60=6.1+lg26/1.8 ↑ [H 2 CO 3 ] H 2 CO 3 HCO 3 - H 2 O CO 2 Cl - H + H + CO 2 H 2 O H + HCO 3 - + + + + K + HCO 3 - Buffered by intracellular buffer system ICF ECF

RESPIRATORY ACIDOSIS ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],- therapy required to restore metabolic balance - lactate solution used in therapy is converted to bicarbonate ions in the liver 40

5. Alteration of metabolism and function ,[object Object],[object Object],[object Object],[object Object]

(Ⅲ). Metabolic alkalosis ,[object Object],[object Object],= 7.4 H 2 CO 3 HCO 3 - 1 20 : = 7.4 HCO 3 - 1 40 : H 2 CO 3

[object Object],[object Object],[object Object],[object Object],2. Primary causes

(1). Excessive gain of HCO 3 - ,[object Object],[object Object]

(2). excessive loss of H + ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Alkaline tide: net HCO 3 - release into the blood stream during gastric acid secretion Sustaining factor: hypokalemia,hypochloremia and hypovolemia chyme

(3). Volume contraction ,[object Object],[object Object],[object Object]

3. compensation ,[object Object],[object Object],[object Object],[object Object]

[object Object],[object Object],[object Object],[object Object],[object Object]

METABOLIC ALKALOSIS - metabolic balance before onset of alkalosis - pH = 7.4 ,[object Object],[object Object],- HCO 3 - increases because of loss of chloride ions or excess ingestion of NaHCO 3 - body’s compensation - breathing suppressed to hold CO 2 - kidneys conserve H + ions and eliminate HCO 3 - in alkaline urine - therapy required to restore metabolic balance - HCO 3 - ions replaced by Cl - ions 1.25 25

4. Alterations of metabolism and function ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

(1). Dysfunction of CNS— hyperexcitability ,[object Object],[object Object],[object Object],[object Object]

(2). Left-shift of oxygen-Hb dissociation curve ,[object Object]

(3) hypocalcemia ,[object Object],[object Object],[object Object],OH - H + Carpopedal Spasm

(4). hypokalemia ,[object Object],[object Object],[object Object]

(Ⅳ). Respiratory alkalosis ,[object Object],[object Object],= 7.4 0.5 20 : = 7.4 H 2 CO 3 HCO 3 - 1 20 : H 2 CO 3 HCO 3 -

2. Primary causes ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

3. classification ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

4. compensation ,[object Object],[object Object]

[object Object],[object Object],[object Object],[object Object],H 2 CO 3 H 2 CO 3 [HCO 3 - ] relatively increase H 2 O CO 2 Cl - H + CO 2 H 2 O H + HCO 3 - + + + + K + HCO 3 - ICF ECF H 2 CO 3 HCO 3 - H + primary decrease of [H 2 CO 3 ] When PaCO2 is 20mmHg, then PaCO2 decrease 20mmHg, and through compensation [HCO3-] decrease 4mmol/L, pH=6.1+lg(24-4)/0.03×20=6.1+lg20/0.6=7.63

RESPIRATORY ALKALOSIS ,[object Object],[object Object],[object Object],[object Object],- hyperactive breathing “ blows off ” CO 2 - body’s compensation - kidneys conserve H + ions and eliminate HCO 3 - in alkaline urine - therapy required to restore metabolic balance - HCO 3 - ions replaced by Cl - ions

5. Alterations of metabolism and function ,[object Object],[object Object],[object Object]

Ⅲ . mixed acid-base disorders

[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],Metabolic acidosis Metabolic alkalosis Respiratory acidosis Respiratory alkalosis Metabolic acidosis Metabolic alkalosis Respiratory acidosis Respiratory alkalosis ,[object Object],[object Object]

1. Metabolic acidosis+ Metabolic alkalosis ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

2. Metabolic acidosis+ Respiratory alkalosis ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

3. Metabolic acidosis+ Respiratory acidosis ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

4. Metabolic alkalosis+ Respiratory alkalosis ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

5. Metabolic alkalosis+ Respiratory acidosis ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Acid Base Balance And Disturbance

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Acid Base Balance And Disturbance