Under normal physiologic conditions, an increase in PCO2 causes a decrease in pH
The increased CO2 is what leads to an increase in hydrogen ions and a slight increase in bicarbonate, as seen by a right shift in the following equilibrium reaction of carbon dioxide: CO2 + H2O -> H2CO3- -> HCO3- + H+
Calculate blood pH from given values
Draw a Davenport diagram to indicate how pH and [HCO3-] alter with changes to PCO2 and changes to non-volatile acid or base
List the primary causes of acid-base disturbances
respiratory or metabolicly caused H+/HCO3- imbalances
Respiratory causes - Alkalosis
hyperventilation = dec Pco2 causing respiratory alkalosis
Increased ventilation, from hypoxic drive in pneumonia, diffuse interstitial lung diseases, high altitude, mechanical ventilation – Hyperventilation – brainstem damage, infection driving fever
Acidosis
Hypoventilation = inc Pco2 causing respiratory acidosis
COPD – Blocked airway – foreign body or tumour – Lung collapse – Injury to chest wall – Drugs reducing respiratory drive, eg morphine, barbiturates, general anaesthetics