Pharm Dyshemogloninemias

Question 1

Carbon Monoxide source

Answer 1

incomplete combustion of carbon containing material (gasses - methane, coal, gasoline)

Question 2

Effects of CO

Answer 2

mild gives flu-like symptoms (headache, nausea, vomiting, dizziness); moderate gives chest pain, blurred vision, dyspnea on exertion, tachycardia, tachypnea, cognitive deficits, myonecrosis, ataxia; severe gives seizures, scoma, dysrhthmias, hypotension, MI/ischemia, skin bullae

Question 3

What is CO mechanism?

Answer 3

binds mitochondrial cytochrome oxidase (complex 4)

Question 4

How does O2sat read in CO poisoning?

Answer 4

pulse oximetry: falsely normal (carboxyhemoglobin read as oxyhemoglobin); arterial blood gas also normal because p02 not affected

Question 5

Treatment for CO poisoning

Answer 5

ABC’s, oxygen (shortens CO T1/2), consider HBO (shortens T1//2 and increases O2)

Question 6

HBO (hyperbaric oxygen)

Answer 6

prevents lipid peroxidation in animal models

Question 7

Weaver Trial

Answer 7

studied patients using HBO - found that helped with long term effects of CO poisoning including memory, attention and concentration

Question 8

When should HBO be used?

Answer 8

when there is loss of consciousness, GCS (coma scale) 10% relative to symptoms; myocardial ischemia, ventricular dysrhthmias, neurological signs 2-4 hours out

Question 9

How do you know if a patient has cyanide poisoning?

Answer 9

1. lactate >10 mmol/L was associated with sig CN levels OR 2. patient does not respond to supportive care with CO alone

Question 10

What is cyanide mechanism?

Answer 10

binds to cytochrome A3 on the electron transport chain (like CO) causing rapid onset of multi-system organ failure because of no ATP

Question 11

What is treatment for cyanide?

Answer 11

hydroxocobalamin and HBO +/- for coexposure with CO

Question 12

What is hydroxocobalamin mechanism?

Answer 12

binds with cyanide to make cyanocobalamin (B12) which is non toxic and excreted

Question 13

When is hydroxocobalamin used?

Answer 13

on any smoke inhalation victim that is not improving with supportive care and any intentional cyanide exposure

Question 14

Methemoglobin

Answer 14

heme iron oxidized to the ferric (+3) form (in normal amounts 1-3%)

Question 15

What is the mechanism of methemoglobin?

Answer 15

rate of heme oxidation is increased while reduction of heme is limited - a structural abnormality of heme

Question 16

What is methemoglobin toxicity?

Answer 16

incapacitates oxygen transport and shifts oxygen dissociation curve to the left - no CNS effects

Question 17

What are the symptoms of methemoglobin? (by percentage in blood)

Answer 17

0-10; asymptomatic 
10-20; cyanosis
20-50; dizziness, fatigue, HA, exertional dyspnea
>50; lethargy/stupor
>70; coma/death

Question 18

What are causes of methemoglobinemia?

Answer 18

congenital, infantile disposition, external causes (drugs including local anesthetics) and toxins

Question 19

How does oxygen saturation appear with methemoglobin?

Answer 19

pulse oximetry is falsely and aberrantly lowered (high 80s, otherwise looks well); arterial blood gas will be falsely normal because p02 not affected

Question 20

What is treatment for methemoglonemia?

Answer 20

ABC’s, decontamination, methylene blue -tetramethyl thionine chloride (specific antidote)

Question 21

Methylene blue mechanism

Answer 21

cofactor of NADPH reductase (gains electron and then donates directly to methemoglobin) which reduces methemoglobin back to +2

Question 22

When is methylene blue used?

Answer 22

when methemoglobin level >20-30% or have symptoms

Question 23

Which people don’t respond to methylene blue?

Answer 23

hemoglobin M disease; G6PD deficiency; CL salts inactivating G6PD; sulfhemoglobinemia; wrong diagnosis

Question 24

What is sulfhemoglobinemia?

Answer 24

has similar symptoms to methemoglobinemia, methemoglobin levels will be elevated, treatment is supportive only!