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Primary Disorder   Defect   Causes Effect on pH and Ratio of Bicarbonate: Carbonic acid  Compensatory Response
Metabolic Acidosis

HCO3-

Decreased

Gain in H+ or loss of HCO3-

 

(A) High anion gap (Acid gain)

1) Ketoacidosis

  • Diabetes
  • Chronic alcoholism
  • Under nutrition
  • Fasting

2) Lactic Acidosis

  • Shock
  • Primary hypoxia due to lung disorders
  • Seizures

3) Renal Failure

4) Toxins Metabolized to acids

  • Alcohol
  • Methanol (formate)
  • Ethylene glycol (oxalate)
  • Salicylates

B) Normal Anion Gap-Acidosis(Bicarbonate loss- Hyperchloremic acidosis)

1) GI HCO3 loss

  • Colostomy
  • Diarrhea
  • Enteric fistulas
  • Ileostomy

2)Urologic procedures

3) Renal HCO3 loss

  • Tubulointerstitial renal disease
  • Renal tubular acidosis

4) Ingestions

  • Acetazolamide
  • CaCl2
  • Mg sulfate (MgSO4)

 

pH –decreased,

Ratio- decreased

 

Respiratory Mechanism-Respiratory Alkalosis(Hyperventilation)

Pa CO2 Decreased 

Renal mechanisms

1) Increased excretion of H+ ions

2) Decreased excretion of K+ ions in the distal tubules

3) Decreased bicarbonate excretion

4)Increased ammonia formation

5) Increased acid phosphate excretion

 

 

Metabolic Alkalosis

HCO3- Increased

Gain in HCO3-or loss of H+ Chloride-responsive alkalosis

  • Loss of gastric secretions – Vomiting, NG suction
  • Loss of colonic secretions
  • Thiazides and loop diuretics (after discontinuation)
  • Cystic fibrosis( Due to loss of chloride in the sweat)
  • Ingestion of large doses of nonabsorbable antacids

Chloride-resistant alkalosis

  • Primary hyperaldosteronism
  • Cushing syndrome
  • Exogenous mineralocorticoids or glucocorticoids
  • Reno vascular hypertension
  • Renin- or deoxy corticosterone-secreting tumors
  • Current use of thiazides and loop diuretics
  • Hypomagnesaemia(Through Hypokalemia)
  • Milk Alkali Syndrome

 

pH increased,

Ratio increased

Respiratory Mechanism-

Respiratory Acidosis(Hypoventilation)

PaCO2 Increased.

Renal Mechanism

1) Decreased excretion of H+ ions

2) Increased excretion of K+ ions in the distal tubules

3) Increased bicarbonate excretion

4) Decreased ammonia formation

5) Decreased acid Phosphate excretion

 

Respiratory Acidosis

PaCO2

Increased

CO2 Retention A) Central

  • Drugs- Sedatives, Alcohol, General Anesthetic agents
  •  Infections
  • Injuries- head trauma
  • Diseases-  Intracranial tumor
  • Syndromes of sleep-disordered breathing, including the primary alveolar   and obesity-hypoventilation syndromes.

B)Airway obstruction

  • Severe asthma,
  • Anaphylaxis
  • Inhalational burn
  • Toxic injury
  • Laryngeal obstruction
  • End-stage obstructive lung disease.

C) Parenchymatous damage /Inflammation

  • Emphysema
  • Bronchitis
  • Adult Respiratory distress syndrome
  • Pleurisy
  • Barotrauma

D) Neuromuscular

  • Poliomyelitis
  • Kyphoscoliosis
  • Myasthenia gravis
  • Muscular dystrophies

E) Misc.

  • Certain congenital heart diseases
  • Mechanical ventilation
  • Rebreathing from a closed space

 

pH- decreased,

Ratio- decreased

Metabolic Alkalosis

HCO3-Increased.

Renal mechanisms 1) Increased excretion

of H+ ions

2) Decreased bicarbonate excretion

3) Increased ammonia formation

4) Increased acid phosphate excretion

 

Respiratory Alkalosis

PaCO2 Decreased

CO2 Washout A) Central nervous system

  • Pain
  • Hyperventilation syndrome
  • Anxiety
  • Psychosis
  • Fever
  • Cerebrovascular accident
  • Meningitis
  • Encephalitis
  • Tumor
  • Trauma
  • Hypoxia
    • High altitude
    • Severe anemia
    • Right-to-left shunts
  • Drugs
    • Progesterone
    • Methylxanthines
    • Salicylates
    • Catecholamines
    • Nicotine
  • Endocrine
    • Pregnancy
    • Hyperthyroidism
  • Pulmonary
    • Pneumothorax/hemothorax
    • Pneumonia
    • Pulmonary edema
    • Pulmonary embolism
    • Aspiration
    • Interstitial lung disease
    • Asthma
    • Emphysema
    • Chronic bronchitis
  • Miscellaneous
    • Sepsis
    • Hepatic failure
    • Mechanical ventilation
    • Heat exhaustion
    • Recovery phase of metabolic acidosis
    • Congestive heart failure

 

pH –Increased,

Ratio- Increased

Metabolic Acidosis

HCO3-Decreased

Renal Mechanism

1)Decreased excretion of H+ ions

2)Increased bicarbonate excretion

3)Decreased ammonia formation

4)Decreased phosphate excretion

 

 

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