• Hyperventilation resulting in excess loss of carbon dioxide
• This will result in increasing pH

Causes

• Psychogenic: anxiety leading to hyperventilation
• Hypoxia causing a subsequent hyperventilation: pulmonary embolism, high altitude
• Early salicylate poisoning -
  • Salicylate overdose leads to a mixed respiratory alkalosis and metabolic acidosis. Early stimulation of the respiratory centre leads to a respiratory alkalosis whilst later the direct acid effects of salicylates (combined with acute renal failure) may lead to an acidosis
• CNS stimulation: stroke, subarachnoid haemorrhage, encephalitis
• Pregnancy