Simple Acid/Base Disorders Flashcards
Simple Acid/base disorder occur if
Renal or respiratory functions abnormal
Acid or base load overwhelm the body
What do respiratory disorder affect
The Partial pressure of CO2
What do renal disorder affect
Bicarbonate concentration
What is important to consider in acid/base disorders
dont just occur in isolation and in otherwise healthy individuals need a combination of factors
What occurs in respiratory acidosis
an acidosis resulting from reduced ventilation, casusing a retention of CO2
this increases CO2, causing the pH to decrease
What is the causes of respiratory acidosis
Acute
- drugs which depress the medullary respiratory centres such as barbiturates and opiates
- Obstruction of major airway
Chronic
- Lung disease
{Bronchitis, emphysema, asthma}
What is the response to respiratory acidosis to protect the pH
Need to Increases HCO3 concentration:
How does HCO3 concentration increase ins response to respiratory acidosis
-Increased partial pressure of CO2 (due to retention of CO2) will increase H+ secretion and increase ability to reabsorbs HCO3
- Acid conditions will stimulate renal glutaminase Increasing NH3+ production so increase the generation of new HCO3 increase reabsorption of
new HCO3
How do you treat respiratory acidosis
Need to correct original disturbance, so only restoration of ventilation can remove primary disturbance
Why in bronchitis which is a case of chronic respiratory acidosis the blood gas values are never normalised but the pH is normal
as the underlying disease process prevents the correction of ventilation but because the kidney maintains high (HCO3) the pH is protected
When does problems arise for patients with lung disease
so problems arise when patients with lung disease develop renal dysfunction
as lung disease patients have chronic respiratory acidosis, but as long as kidney function is not impaired pH can be maintained at a level compatible with life
Why is there a smaller decrease in pH in chronic respiratory acidosis than in acute respiratory acidosis
This is due to the mechanism to raise (HCO3) and balance out the pH,
as renal compensations takes time due to renal glutaminase taking 4-5 days to reach maximum,
So acutely there is a big drop in pH as renal compensation hasn’t kicked in, but chronic there isn’t a great change in pH as is controlled by renal compensation
What is occurs in respiratory alkalosis
alkalosis of respiratory origin so must be due to fall in PCO2 and this can only occur through increased ventilation and CO2 blow off
What is the causes of respiratory alkalosis
Acute
- Voluntary hyperventilation
- Aspirin
- First ascent to altitude
Chronic
- Long tem residue at altitude
How does altitude increased affect your PCO2
decrease Partial pressure of oxygen to <60mmHg(kPa) stimuates peripheral chemoreceptors to increase ventilation, increased ventilation causes fall in PCO2
What is the response to respiratory alkalosis to protect the pH
(HCO3) should decreases
How does HCO3 concentration decrease ins response to respiratory alkalosis
if decreased PCO2, less H+ is available for secretion
therefore less filtered load of HCO3- is reanbsorbed so HCO3 is lost in the urine