Acid Base Balance

Normal pH range in body

7.35-7.45

Sources of H+ (2)

Cell metabolism (CO2) → Higher CO2 equates to higher H+

Metabolic intermediate biproducts

Metabolic intermediate biproducts (4)

Pyruvic acid

Lactic acid

Acetoacetic acid

Fatty acid

H+ external sources (8)

Grains

Nuts

Dairy

Citric acid in food

Legumes

Meats

Medications

Disease processes e.g. diabetes

Bicarbonate sources (3)

Fruits

Vegetables

Ant-acids e.g. tums

Acidosis effects (2)

Neurons become less exciteable

CNS depression

Alkalosis effects (2)

Neurons become hyperexciteable

Tingling/twitches

Aldosterone K+ effect (1)

K+ excretion when [K+] is high

Hyperkalemia effect (1)

Cardiac arrythmia

Hypokalemia effects (3)

Muscle weakness

Failure of respiratory muscles

Heart failure

Acidosis effect on K+ (2)

Kidney K+/H+ exchanger excretes H+ and retains K+

Resultant K+ affects cardiac functions

Unbalanced pH effect of enzymes (2)

Enzymes can become non-function

Affects metabolic activity

pH homeostasis mechanisms (3)

Buffers → combine/release H+ → fastest response

Ventilation → 75% of disturbances

Renal regulation → slowest of the three (3-5 days) → directly excreting/reabsorbing H+

Buffer types (3)

Phosphate

Protein (e.g. Hemoglobin)

Bicarbonate

Respiratory correction for acidosis (1)

Increased breathing

Respiratory correction for alkalosis (1)

Decreased breathing

Kidney correction for acidosis (1)

Type A intercalated cells secrete H+ & reabsorb HCO3-

Kidney correction for alkalosis (1)

Intercalated B cells secrete HCO3- and reabsorb H+

pCO2 normal range

35-45

HCO3- normal range

22-26

Acute respiratory alkalosis values (3)

High pH

Low pCO2

Normal HCO3-

Causes of acute respiratory alkalosis (9)

Anxiety

Hypoxia

Lung disease

CNS disease

Drug use → salicylates, catecholamines, progesterone

Pregnency

Sepsis

Hepatic encephalopathy (brain dysfunction due to liver dysfunction)

Mechanical ventilation

Acute respiratory acidosis values (3)

Low pH

High CO2

Normal HCO3-

Acute respiratory acidosis causes (8)

CNS depression (e.g. from drugs, CNS event)

Neuromuscular disorders (e.g. myopathies, neuropathies)

Acute airway obstruction

Pneumonia

Pulmonary edema

Impaired lung motion (e.g. hemothorax, pneumothorax)

Thoracic cage injury

Ventilator dysfunction

Chronic respiratory acidosis causes (3)

Chronic lung disease

Chronic neuromuscular disorders

Chronic respiratory center depression → central hypoventilation

Metabolic alkalosis values (3)

High pH

Normal pCO2

Normal-high HCO3-

Metabolic alkalosis causes (5)

Vomiting

Diuretics

Excess mineralocorticoid activity

Excess alkali administration

Refeeding alkalosis

Metabolic acidosis values (3)

Low pH

Normal pCO2

HCO3- normal-low

Metabolic acidosis non-gap causes (3)

GI HCO3 loss (e.g. diarrhea, ureteral diversions)

Renal HCO3 loss (e.g. RTA, aldosterone inhibitors, carbonic anhydrase inhibitors)

Iatrogenic: normal saline

Metabolic acidosis anion-gap causes (5)

Ketoacidosis (e.g., diabetic, alcoholic)

Renal failure

Lactic Acidosis

Rhabdomyolysis

Toxins (e.g. methanol, ethylene glycol, paraldehyde, salicylates)