Dyshemoglobinemias

Question 1

Hyperbaric oxygen MOA

Answer 1

Prevents lipid peroxidation and delayed sequelae in CO poisoning

Question 2

CO Effects

Answer 2

1. Mild: headache, nausea, vomiting, dizziness
2. Moderate: CP, blurred vision, dyspnea on exertion, tachycardia, tachypnea, cognitive deficits, ataxia, myonecrosis
3. Severe: Seizures, coma, hypotension, dysrhythmias

Question 3

Chronic effects of CO exposure

Answer 3

Cognitive dysfunction, dementia, psychosis, amnesia, parkinson’s, blindness, incontinence, neurpathy. Usually preceded by 2-40 day lucent period. Effects more likely if pt lost consciousness

Question 4

Evaluate suspected case of CO poisoning for:

Answer 4

1. End organ manifestations of disease: CNS, cardiac, perfusion
2. CO levels: pulse ox will be falsely normal or high, ABG is the most accurate

Question 5

Treatment for CO poisoning

Answer 5

Oxygen, hyperbaric oxygen in severe cases

Question 6

Indications for hyperbaric oxygen

Answer 6

1. Loss of consciousness
2. CO > 10%
3. Myocardial ischemia, ventricular dysrhythemias
4. Neurologic signs: GCS <15

Question 7

Cyanide mechanism

Answer 7

Binds to cytochrome A3 on ETC, preventing formation of ATP. Leads to rapid multi-organ failure

Question 8

Nitrites Indication

Answer 8

CN poisoning antidote, Part of cyanide antidote kit

Question 9

Nitrite Concerns

Answer 9

Dangerous to use in concurrent CN and CO poisonings

Question 10

Sodium Thiosulfate Indication

Answer 10

CN poisoning, Part of cyanide antidote kit

Question 11

Nitrite MOA

Answer 11

Attract CN from the Fe3+ on the cytochrome to the Fe2+ on the Hemoglobin

Question 12

Sodium Thiosulfate MOA

Answer 12

Enhances normal metabolism of CN through rhodanase enzyme

Question 13

Hydroxycobalamin (VB12A) Indications

Answer 13

CN poisoning, part of cyanide antidote kit

1. Smoke inhalation pt who is not improving with oxygen
2. Intentional CN exposure
3. Few side effects: increase BP

Question 14

Hydroxycobalamin (VB12A) MOA

Answer 14

Binds with CN to make Vitamin B12, which can be excreted

Question 15

Methemoglobin MOA

Answer 15

1. Heme iron oxidized to the +3 state, normal amounts are 1-3%.
2. Incapacitates oxygen transport: shifts dissociation curve to the left (oxygen less willing to unload from Hemoglobin at the tissues b/c bound more tightly

Question 16

Methemoglobin Symptoms

Answer 16

1. 0-10%: asymptomatic
2. 10-20%: apparent cyanosis
3. 20-50%: dizziness, fatigue, headache, dyspnea
4. > 50%: Lethargy
5. > 70%: coma and death

Question 17

Methemoglobin Pulse Ox

Answer 17

Falsely low, usually around 87%. Use ABG instead

Question 18

Methemoglobin Treatment

Answer 18

1. ABCs
2. Decontamination
3. Methylene blue (tetramethylthronine choride)

Question 19

Methylene Blue Indications

Answer 19

1. Methemoglobin level >20-30% or symptoms

Question 20

Methylene Blue Side Effects

Answer 20

1. Painful injection site
2. Hemolytic anemia from weak oxidizing capacity
3. Dyspnea, restlessness, tremor, precordial pain

Question 21

Methylene Blue MOA

Answer 21

NADPH reductase (Cofactor), gains an electron and donates it directly to the Fe3+, reducing it to Fe2+