Acutely ill patient Flashcards
What organs help maintaing the aci-base balance and arterial blood pH?
The kidneys - remove acid + regenerate bicarbonate
Lungs - regulate the removal of acid (CO2) by varying respiratory rate
Liver - removes and recycles lactate
What is the pH determined by?
pH is determined by the ratio of
HCO3– to CO2
What does the kidney buffering system control?
hydrogen (H+) and bicarbonate (HCO3–) excretion or reabsorption
the conversion of ammonia (NH3) to ammonium (NH4+) in the urine
What does the lung buffering system control?
carbon dioxide (CO2) in the blood - increasing expired CO2 when more is produced or to compensate for metabolic acidosis
In which 3 types of acute illness is there a risk of acid-base abnormalities?
chronic kidney disease (eGFR
What are dangerous pH levels?
Below pH 7.1 or above pH 7.6
What principle is the Stewart approach, termed the Strong Ion Difference (SID) based on and who is it favoured by?
Based on the principle that the serum bicarbonate concentration does not alter blood pH
This approach is favoured by intensivists and anaesthetists
What does severe acidaemia (pH
cardiac function and vascular tone.
What does severe alkalaemia (pH >7.6) affect?
irritability of cardiac and skeletal muscle
What conditions are associated with acid-base disorders?
vomiting/diarrhoea cardiogenic or septic shock hypovolaemia acute kidney injury respiratory failure altered neurological status decompensated diabetes prolonged and excessive infusions of 0.9% sodium chloride
What should you do if acid-base disturbance is suspected?
perform following: Urea, creatinine and electrolytes Bicarbonate Chloride Arterial blood gases (including lactate)
What is a normal anion gap?
5-11 mmol/l
What does an abnormal ion gap indicate?
increase in anion gap indicates
acidosis
decrease in anion gap indicates
alkalosis.
What can cause high anion gap acidosis?
Methanol Uraemia Diabetes Paraldehyde Alcohol Lactate Ethelyne glycol Salicylate (aspirin)
How do you calculate osmolality?
2 X [Na+] + glucose + urea
