Assignment global acute respiratory acidosis questions
Assignment global acute respiratory acidosis questions
In the space that follows you will find a series of cases that include arterial blood
gases. Each case is then followed by an explanation of the acid-base status, the
oxygenation status and a summary of the patient’s clinical picture.
The explanations of the acid-base status utilize the 5-step approach to
interpreting acid-base status that is laid out in the Arterial Blood Gas Primer,
which you can access by clicking here. In some of the cases below, information
is not available to calculate the anion gap or the delta delta. In such cases, you
should focus solely on identifying the primary and compensatory processes.
Case 1:
A 24 year-old woman is found down in Pioneer Square by some
bystanders. The medics are called and, upon arrival, find her with an
oxygen saturation of 88% on room air and pinpoint pupils on exam. She is
brought into the Harborview ER where a room air arterial blood gas is
performed and reveals: pH 7.25, PCO
2
60, PO
2
65, HCO
3-
26, Base Excess 1.
On his chemistry panel, her sodium is 137, chloride 100, bicarbonate 27.
Acid-base status:
• The patient has a low pH (acidemia)
• The PCO
2
is high (respiratory acidosis) and the bicarbonate is at the upper
end of normal. The low pH and high PCO
2
imply that the respiratory acidosis
is the primary process
• The anion gap is 10 and is, therefore, normal. The patient does not have an
elevated anion gap acidosis.
• There is no compensatory process. Although the measured bicarbonate is
just above normal, the base excess of 1 tells us that there is no metabolic
alkalosis
• The delta gap is 10 -12 = -2 and the delta-delta is -2 + 27 = 25. There is,
therefore, no metabolic process.
• Summary: An acute, uncompensated respiratory acidosis leading to
acidemia.
Alveolar-arterial oxygen difference:The alveolar-arterial difference is 10
mmHg, a normal value, which tells us that her hypoxemia is entirely due to
hypoventilation.
Explanation for the clinical picture: The respiratory acidosis implies that the
patient is hypoventilating. This fact, in combination with the pinpoint pupils
suggests the patient is suffering from an acute narcotic overdose. In this case,
the narcotic is most likely heroin.