Metabolic acidosis Flashcards
What should arterial pH be maintained at?
7.35-7.45
What should intracellular pH be maintained at?
7-7.3
Which organs work together to control body pH
Lungs& kidney
List the different acid base disorders
- Metabolic acidosis
- Metabolic alkalosis
- Respiratory acidosis
- Respiratory alkalosis
What are the characteristics(pH, primary disturbance& compensatory response) of Metabolic acidosis
pH= low
primary disturbance= low bicarbonate ion( HCO3-)
compensatory mechanism= decreased PCO2( so hyperventilation occurs)
What are the characteristics(pH, primary distrubance& compensatory response) of Metabolic alkalosis
pH=high
primary disturbance= increased concentration of bicarbonate ion
Compensatory response= increased PCO2 so hypoventilation occurs
What are the characteristics(pH, primary distrubance& compensatory response) of respiratory acidosis
pH=low
primary disturbance= increased pco2
Compensatory response= increased concentration of bicarbonate ion
What are the characteristics(pH, primary distrubance& compensatory response) of respiratory alkalosis
pH=high
primary disturbance= reduced pco2
Compensatory response= readuced concentration of bicarbonate ion
What is metabolic acidosis
-A low arterial blood pH in conjuction with a reduced serum HCO3- conc.
What is the normal range for serum bicarbonate ion conc.?
24-26mmol/L
What is the anion gap?
- Usually around 8-12mmol/L
- The difference between the primary measured cations(na+ and k+) and the primary measured anions( Cl- and HCO3-)
- Determines the presence of metabolic acidosis
- Since there are more unmeasured anions than unmeasured cations, the value of anion gap is usually positive.
What can we say about the neutrality of plasma with regards to the anion gap?
- Plasma is always electroneutral
- Measured cations+ unmeasured cations=measured anions+ unmeasured anions
What does an increased anion gap indicate?
-An increase in the concentration of anions other than chloride or bicarbonate
What is the clinical correlation with the anion gap?
-The anion gap identifies an abnormal increase in plasma anions
Outline the increased anion gap acidosis
- Caused by increased amount of organic acids
- The h+ ions are buffered by bicarbonate ions
- The negatively charged organic acid component e.g lactate ion contributes to the proportion of unmeasured anions, resulting in an increased anion gap.
Outline the normal anion gap acidosis
- Loss of bicarbonate ions
- Kidney compensates by increasing reabsorption of chloride ions
- cL- ions are included in our anion gap calculation so anion gap remains normal and plasma remains electroneutral
- May also be referred to as hyperchloraemic acidosis
- The serum is acidotic cos there are fewer bicarbonate ions to buffer the hydrogen ions
What causes normal anion gap acidosis?
- ) GI losses of bicarbonate:
- diarrhoea
- surgical drains/fistulae - ) Renal losses of bicarbonate:
- renal tubular acidosis( may be caused by decreased bicarbonate reabsorption in the distal convuluted tube
Why doesnt vomiting usually cause acidosis?
-Cos even though there is loss of bicarbonate, there is also loss of hydrogen ions from gastric acid.
What is the cause of increased anion gap acidosis?
pneumonic GOLDMARK Glycols(ethylene, propylene) Oxyproline Lactate (lactic acidosis- salicylates/shock) D-lactate Methanol poisoning Aspirin Renal failure Ketoacidosis (diabetics)
What is lactic acidosis and what causes it?
- Result of lactate production- anaerobic respiration
- Caused by shock:
1. )hypovolaemic
2. ) cardiogenic
3. )anaphylactic
4. ) septic
What is ketoacidosis and what causes it?
- Result of ketone production, fat metabolism
- Main causes: diabetes, starvation and alcohol
What is the desired range for arterial pH ?
7.35-7.45
What is the desired range for paco2 ?
4.5-6kPa
What is the desired range for pao2 ?
10-13kPa
What is the desired range for HCO3- ?
24-26mmol/L
What is the desired range for o2 sat?
96-100%
What is the desired range for base excess?
+/- 2 mEq/L
How is respiratory acidosis/alkalosis compensated for
Renal compensation(metabolic)
How is metabolic acidosis/alkalosis compensated for
Respiratory compensation
