Dyshemoglobinemias

Question 1

CO absorption/excretion?

Answer 1

Direct respiration

Question 2

Chemical converted to CO in vivo?

Answer 2

Methylene chloride

Question 3

4 effects of CO?

Answer 3

(1) Bind hemoglobin with high affinity (shift O2 dissociation curve left, decrease 2,3-BPG) (2) Bind myoglobin (direct myocardial toxicity) (3) Bind mitoch cycochrome oxidase (inhibit cellular respiration) (4) Displace NO from platelets and form peroxynitrites (CNS toxicity)

Question 4

Risk of delayed neurological effects with CO poisoning?

Answer 4

Increased age (>30), Loss of consciousness

Question 5

O2 Sats with CO poisoning?

Answer 5

Pulse ox normal, Co-ox appropriate, Calculation normal

Question 6

Hyperbaric oxygen mxn?

Answer 6

Prevent lipid peroxidation and prevent delayed neurologic sequelae

Question 7

Indications for HBO?

Answer 7

Loss of consciousness, GSC10%, MI/Ventricular dysrhthmias, Neurologic signs 2-4 hours “out”

Question 8

How to distinguish between CN and CO?

Answer 8

Lactate>10 with associated significant CN levels or a pt that does not respond to supporting care with oxygen

Question 9

Nitrites for CN mxn?

Answer 9

attract CN from Fe3+ on cytochromes to Fe3+ in hemoglobin to form methemoglobin

Question 10

Contraindication for nitrites?

Answer 10

Dangerous if concurrent CO poisoning

Question 11

Enhances normal metobalism of CN? Through what enzyme?

Answer 11

Sodium thiosulfate through rhodanase

Question 12

Best treatment for CN toxicity?

Answer 12

Hydroxycobalamin (Cyanokit)

Question 13

Hydroxycobalamin mxn?

Answer 13

Binds with CN to form excretable cyanocobalamin

Question 14

Indications for hydroxocobalamin?

Answer 14

Smoke inhalation pt not improving with supportive care, known CN exposure, nitroprusside at risk pts

Question 15

Give hydroxocobalamin wtih?

Answer 15

Sodium thiosulfate

Question 16

Methemoglobin O2 sats?

Answer 16

Pulse ox falsely lowered to high 80s, Co-ox appropriate, Calculation falsely normal

Question 17

Specific antidote for methemoglobin and mxn?

Answer 17

Methylene blue: Cofactor of NADPH reductase. Gains an electron and donates it directly to reduce methemoglobin to hemoglobin

Question 18

Methylene blue indicated for?

Answer 18

Methemoglobin level > 20-30%

Question 19

Side effects of methylene blue?

Answer 19

Hemolytic anemia (weak oxidizing ability), pain at injection site, dyspnea, restlessness, tremor, apprehension, precordial pain

Question 20

Non-responders to methylene blue?

Answer 20

Wrong diagnosis, G6PD deficiency, CL salts inactivating G6PD, Sulfhemoglobinemia, Hemoglobin M disease

Question 21

Acquired methemoglobinemia?

Answer 21

Nitrites