Imagine this case:
-An obese pt BIBEMS for a change in mental status
-You get a STAT CTH, which is neg for any acute findings
-Pt becomes very agitated and is given Haldol for safety but requires repeat dosing
-After repeat dosing, patient calms down
-You obtain an EKG because of repeat doses of Haldol but it shows no QTc prolongation
-You hear the monitor alarm go off and come back to see the patient is hypxoic
-You obtain a stat portable CXR, which is clear
-You put the patient on supplemental oxygen via NC and improve his saturation to 99%
-You admit the patient to Medicine for AMS
Potential Hospital Course:
-12 hours later on medicine floor, pt has cardiac arrest
-Has ROSC after intubation
-Eventually discharged with presumed mild hypoxic injury
The Discussion Points:
- Any sedated patient should have Cardiac and Pulse ox monitoring (which you should constantly reassess)
- If a pt is not on oxygen and their pulse ox is above 96 or 97%, you know that pt has a pCO2 of 50 or less
- In other words, you can tell if a patient’s pCO2 is rising when their pulse ox is concomitantly going down
- However, once a pt is on supplemental oxygen, you cant tell the pt’s pCO2 based on SpO2 anymore.
- In this case, the pt should be placed on end tidal CO2 to monitor the pCO2 and the direction it is going in.
- Even if the pt is not on supplemental oxygen, there is the argument that ETCO2 is an earlier warning sign that the CO2 is going up compared to watching the pulse ox going down
- That being said, it has never been shown that this earlier warning in a pt not on oxygen makes a clinical difference
- Be especially cognisant when sedating an obese patient for worry of Obesity Hypoventilation Syndrome