Lecture 46: Acid Base Pathophysiology Flashcards
what is the biggest source of acid in the body and how is it excreted
- carbonic acid from cell resp
- excreted by lungs
what is another source of acid in body and how is it excreted
- non-carbonic in volatile acid from cell metabolism
- excreted by kidneys
what is the pH buffer equation
CO2 + H20 H2CO3 H+ + HCO3-
outline how asthma an cause acute respiratory alkalosis
- acute asthma
- irregular bronchoconstriction
- ventilation/perfusion mismatch –> hypoxia and hypocapnia
- acute resp alkalosis
how is acute resp alkalosis as a result of asthma treated
use bronchodilators
outline how asthma can cause acute respiratory acidosis
- asthma deterioration
- fatigue
- -> hypoventilation
- -> hypoxia and normocapnia
- -> hypercapnia
- acute resp acidosis
hos is acute resp acidosis as a result of asthma treated
assisted ventilation
outline how hyperventilation can cause acute resp alkalosis and chronic resp alkalosis
- anxiety –> ^ ventilation
- -> hypocapnia, ^ resp exchange ratio, tetany
- acute resp alkalosis
- chronic
- -> hypocapnia, normalisation of resp exchange ratio, renal compensation
- chronic resp alkalosis
how would you treat/reverse acute resp alkalosis and chronic resp alkalosis as a result of hyperventilation
- reassure Px and explain
- treat cause 2nd to other disease
- treat underlying disease
outline how COPD causes chronic resp acidosis
- normal ventilation –> impaired ventilation and ventilation perfusion mismatch
- hypoxia and hypercapnia
- chronic resp acidosis
- exacerbations –> further hypoventilation
- more hypercapnia
- acute on chronic resp acidosis
list the causes of resp alkalosis
- hyperventilation
- -> acute
- -> chronic
- -> anxiety
- -> 2nd to other systemic disease
- hypoxia
- -> altitude
- -> ventilation perfusion mismatch
- -> asthma
- -> pulmonary vascular disease
- liver disease
- heart failure
- intake of resp stimulants
- -> aspirin
list causes of resp acidosis
- hypoventilation
- -> acute:
- resp centre
- resp muscles
- asthma
- airway obstruction
- -> chronic:
- COPD
- restriction
- intake of resp depressants
- -> morphine, barbiturates
list causes of metabolic alkalosis
- gastric secretion loss
- -> vomiting
- -> nasogastric suction
- hyperaldosteronism
- hypovolaemia
- post hypercapnia
- alkali ingestion
- -> antacids
- -> bicarbonate
- -> citrate e.g. blood transfusions
- diuretics
- -> inhibition of lumen negativity
- -> aldosterone response
- sweat loss in cystic fibrosis
- hypokalaemia –> movement of H+ into cells
list the causes of metabolic acidosis
normal anion gap:
- renal tubular acidosis
- chronic renal disease occasionally
- diarrhoea
- ingestion
- -> ammonium chloride
increased anion gap
- chronic renal disease
- lactic acidosis
- ketoacidosis
- liver disease
- ingestion of acids
- -> aspirin
- -> methanol
- -> ethylene glycol
how is chronic resp acidosis as a result of COPD treated
- bronchodilators
- inhaled steroids
- controlled O2 therapy
- assisted ventilation
outline how COPD can cause metabolic alkalosis
- too high FIO2
- more hypercapnia
- assisted ventilation
- normocapnia
- post hypercapnic metabolic alkalosis
outline how CKD can result in metabolic acidosis
- failure to excrete non-carbonic acids and failure to reabsorb bicarbonate
- high anion gap metabolic acidosis
- failure to excrete K
- hyperkalaemia
- H+ displaced from cells
- further metabolic acidosis
how is metabolic acidosis as a result of CKD treated
- give bicarbonate
- treat cause of kidney disease
- alter diet
- fluid balance
- dialysis
- transplant
outline how type 1 renal tubular acidosis can result in metabolic acidosis
- failure to secrete H+ (distal tubular)
- normal anion gap metabolic acidosis
- failure to secrete and excrete K+
- hyperkalaemia
- further metabolic acidosis
how is metabolic acidosis as a result of type 1 renal tubular acidosis treated
give bicarbonate
outline how type 2 renal tubular acidosis can result in metabolic acidosis
- failure to reabsorb bicarbonate (proximal tubular)
- normal anion gap metabolic acidosis
how is metabolic acidosis as a result of type 2 renal acidosis
give bicarbonate (requires large doses)
what can occur in a Px w/ type 1 and treated type 2 renal tubular acidosis
unusual combination of acidosis and hypokalaemia
outline how diarrhoea can result in metabolic acidosis
- loss of fluids and bicarbonate
- normal anion gap metabolic acidosis
- loss of K+
- unusual combination of acidosis w/ hypokalaemia
how can metabolic acidosis as a result of diarrhoea be treated
give fluids and electrolytes
outline how vomiting can result in metabolic alkalosis
- loss of gastric acid
- metabolic alkalosis
- loss of K+
- hypokalaemia
- further alkalosis
- loss of fluids
- hypovolaemia
- hyperaldosteronism
- further metabolic alkalosis
- inability of kidneys to excrete bicarbonate
- prolongation of alkalosis
outline how hyperaldosteronism can result in metabolic alkalosis
- hyperaldosteronism
- ^ H+ secretion
- metabolic alkalosis
- ^ K+ secretion
- hypokalaemia
how might metabolic alkalosis as a result of hyperaldosteronism be resolved
adrenalectomy
outline how hypoaldosteronism can result in metabolic acidosis
- hypoaldosteronism
- reduced H+ secretion
- normal anion gap metabolic acidosis
how might metabolic acidosis as a result of hypoaldosteronism be resolved
give aldosterone
outline how diabetic ketoacidosis can result in metabolic acidosis
- low cell glucose
- shift to fat metabolism
- mitochondria overwhelmed
- acetone, acetoacetate and B-hydroxybutarate
- high anion gap metabolic acidosis
- K+ from cells
- loss in diuresis
- hyperkalaemia
how can metabolic acidosis as a result of diabetic ketoacidosis be treated
- insulin
- fluids
- bicarbonate
- electrolytes
outline how hepatocellular dysfunction can cause resp alkalosis and metabolic alkalosis
- abnormal levels of toxins and hormones stimulate resp centre
- chronic resp alkalosis
- hypoalbunimaemia
- further metabolic alkalosis
outline how hepatocellular dysfunction can result in metabolic acidosis
- abnormal amino acids and other acids
- metabolic acidosis
how might metabolic acidosis as a result of hepatocellular dysfunction be resolved
- treat underlying cause e.g. alcohol abuse
- liver transplant
outline how salicylate ingestion can result in metabolic acidosis
- non carbonic acid
- high anion gap metabolic acidosis
outline how salicylate ingestion can result in resp alkalosis
- stimulation of ventilation
- additional hyperventilation
- resp alkalosis
how might resp alkalosis as a result of salicylate ingestion be resolved
forced alkaline diuresis
outline how IV saline pH 7.0 can result in metabolic acidosis
- dilution of bicarbonate
- hyperchloraemia
- metabolic acidosis
how might metabolic acidosis as a result of IV saline pH 7.0 be resolved
citrate based infusions
