SAQ 773 – Respiratory – acute respiratory acidosis and oxygen-induced hypercapnia

An 80-year-old man is transferred from his nursing home with altered conscious state. His arterial blood gas on room air is shown.

Interpret the arterial blood gas, stating three (3) points.

(Marked out of 3.0)

Arterial blood gas

Test	Result	Reference range
FiO2	0.21
pH	7.09	7.35-7.45
PaCO2	72 mmHg	35-45
HCO3	27 mmol/L	22-26
PaO2	50 mmHg	80-100

/ 3

Show four (4) calculations to justify your interpretation.

(Marked out of 4.0)

/ 4

Give two (2) likely causes for his acid-base status and, for each, one (1) intervention likely to quickly reduce PaCO2. Do not repeat the same intervention.

(Marked out of 4.0)
</p> <table class="saq-prop-table" style="width: 100%; max-width: 100%; table-layout: fixed; border-collapse: collapse;"> <thead> <tr> <th style="overflow-wrap: anywhere; word-break: normal; white-space: normal; vertical-align: top; box-sizing: border-box;">Cause</th> <th style="overflow-wrap: anywhere; word-break: normal; white-space: normal; vertical-align: top; box-sizing: border-box;">Intervention</th> </tr> </thead> <tbody> <tr> <td style="overflow-wrap: anywhere; word-break: normal; white-space: normal; vertical-align: top; box-sizing: border-box;">1</td> <td style="overflow-wrap: anywhere; word-break: normal; white-space: normal; vertical-align: top; box-sizing: border-box;"></td> </tr> <tr> <td style="overflow-wrap: anywhere; word-break: normal; white-space: normal; vertical-align: top; box-sizing: border-box;">2</td> <td style="overflow-wrap: anywhere; word-break: normal; white-space: normal; vertical-align: top; box-sizing: border-box;"></td> </tr> </tbody> </table> <p>

/ 4

What is his oxygen saturation approximately?

(Marked out of 1.0)

/ 1

If a patient with chronic CO2 retention receives excessive oxygen, list two (2) important mechanisms by which CO2 may rise.

(Marked out of 2.0)

/ 2

Total Score: 0 / 14

Percentage: 0%