Lecture: Toxicology: Antipsychotics and Opioids

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Antipsychotics and Opioids - Alex

CO Poisoning

That was a good case by Neil below.

A study in Annals showed that venous measurements of CO level accurately reflect arterial levels. Ann Emerg Med. 1995 Apr;25(4):481-3.

I will make the follow comments advocating arterial blood sample, though:

1. Few patients in the above study had high CO levels (>20%)
2. Pulse oximeter will give falsely elevated O2 sat values even in cases of extremely high COHb levels (Ann Emerg Med. 1994 Aug;24(2):252-5). In the setting of concomitant hypoxia (smoke inhalation), only an arterial sample will give an accurate measurement of arterial oxygen content when measured by lab CO-oxymetry Chest. 1998 Oct;114(4):1036-41.
3. ABG will allow evaluation for metabolic acidosis, which is very important, as several studies have shown that the degree of acidosis is a better predictor of severity than absolute CO level. J Accid Emerg Med. 1999 Mar;16(2):96-8 This is partially b/c CO also binds intracellular cytochromes needed for oxidative metabolism.
-Alex

CO Poisoning

Case Summary: A daughter, mother and grandaughter present to Jeff ED c/o nausea, lightheadedness, vomiting, and headache for several hours. The CO Monitor at home went off this afternoon s/p the furnace was turned on for the first time this morning.

DX: CO Poisoning

Plan:

1) Start pt on 100% High Flow Oxygen Mask.
2) Draw carboxy hemoglobin levels

Results/TX/What I learned:

The patients carboxy levels were elevated-- 10%, 22%, and 36% for D, Mom, and Grand Mom, respectively. CO levels can be elevated in smokers (10% is nml). CO has a half life of 4-8 hours. With high flow o2 mask, this half life is reduced to 60 mins. (with hyperbaric 02 chamber, halflife is reduced to 23 mins) Pts were left on mask for 2 hours, and then D/C'd. Common symptoms with CO exposure include lightheadedness, headaches, N/V. Blood venous PO2 measurements tend to be normal, because PO2 reflects O2 dissolved in blood and this process not affected by CO. In contrast, hemoglobin-bound O2 (which normally comprises 98 percent of arterial O2 content) is profoundly reduced in the presence of COHb. In this case, venous blood was sent.

Case: Opisthotonos

19 yo male presents with neck spasms, back spasms and trismus after ingesting several unknown pills 2 days ago and smoking crack today.
VS: HR 170's, BP: 150/100
PE: Young male in severe distress with neck and back in full extension, unable to relax muscles
ER course: Treated with IV ativan, benadryl and cogentin with full relief of symptoms
What we learned: Opisthotonos has a wide differential, including tetanus, dystonic reaction (from meds like compazine), intracranial hemorrhage, strychnine, meningitis.
-Neil and Alex