Case 1: Use the following lab results to answer the
CO2 = 39; pCO2 = 40; pH = 7.6; K = 3.0. The patient has been
a. List the condition - acidosis or alkalosis, metabolic or
respiratory, compensated or uncompensated.
Use Table 2. pH = 7.6 and K = 3.0 both indicate an alkalosis
condition. The pCO2 = 40 value is normal and therefore indicates
a metabolic condition. The CO2= 39 value is measuring HCO3- and
indicates an uncompensated condition.
Therefore, Metabolic Alkalosis - Uncompensated.
b. What is the primary cause of the condition?
Consult Table 2 and answer (a) above and consider the vomiting.
This indicates a high pH and therefore deficit of H+.
c. Explain the other lab results using the primary cause and
Solution: Use the equilibrium:
CO2 + H2O === H2CO3 === H+ + HCO3-
pCO2 is normal. If pH is increased and H+ ions are decreased,
the equilibrium shifts to the right and HCO3- is increased as
indicated in the CO2 = 39 value.
d. State and explain how the compensation will return pH to
normal using equilibrium principles.
Table 2 indicates that the lungs retain CO2. If CO2 is increased,
the equilibrium in (c) will shift right and H2CO3- and H+ ions
will increase, therefore the pH will decrease.
f. Explain how the treatment with NH4Cl will work?
NH4Cl is a salt of a weak base, therefore, its solution is
acidic, therefore an increase of H+ ions will correct a H+ deficit
and decrease the pH.
NH4Cl + HOH <===> NH4OH + H+ + Cl
weak base strong acid