Acid base disorders Flashcards
_ is the most important way of preventing H+ accumulation in the body
exhaling CO2 via the lungs
what is PH
the negative logarithm to base 10 of H+ activity expressed in concentration
ph = -log10 [H+]. OR log 1/[H+]
reference interval of arterial blood ph
7.35 -7.45
what is pKa
this is the negative logarithm of the ionization constant of a WEAK acid
the stronger the acid
the lower the pka
the higher the pka
the stronger the conjugate base
what is a buffer
compound that resists a change in ph when a strong acid or base is added to the system
when do buffers work best at resisting ph change
in the interval of one ph unit of its pka when ratio of acid : base is (1:10/10:1)
pka of bicarbonate buffer
6.1 (makes it a poor buffer)
most important buffer
bicarbonate buffer (most abundant)
what is compensation
when the body’s innate mechanisms are able to maintain/attempt to maintain homoeostasis in the face of acid-base disturbance
henderson/hasselbach equation
ph = pka + log (base)/(acid) = 20/1
reference interval for anion gap is
6-22mmol/l
normal gap metabolic acidosis is also called
hyperchloraemic metabolic acidosis
what causes chloride responsive metabolic alkalosis
volume depletion (contraction alkalosis)
characteristics of chloride responsive metabolic alkalosis
1) renal retention of HCO3
2) urinary Cl- = <10mmol/l
3) increased exchange of sodium for potassium & H+
chloride resistant metabolic alkalosis is associated with _
presence of an underlying disease
e.g Cohn’s, Cushing’s or Bartter’s syndrome
characteristics of chlorine resistant metabolic alkalosis
1) urine chlorine > 20mmol/l
2) excessive loss of K+, H+ & Cl-
3) increased reabsorption of Na+ & HCO3-
metabolic acidosis can coexist with alkalosis in
DKA + CCF on diuretics
metabolic acidosis & resp. alkalosis can exist in
salicylate (aspirin) overdose
metabolic alkalosis & resp acidosis exists in
COAD + diuretics
metabolic acidosis & alkalosis + resp. alkalosis can occur in
vomiting, sepsis + dehydration
metabolic acidosis & alkalosis + resp. alkalosis can occur in
vomiting, sepsis + dehydration
plastic containers not recommended for sample collection because
- they are not air tight
*blood must be collected anaerobically & transported in ice sludge
HCO3 - reference interval
18-31mmol/l
(H+) & PCO2 reference interval
35-45 (mmol/l. // mmHg)
pO2 reference interval
83-108mmHg
