Dyshemoglobinemia Treatment

Question 1

Which gases most often cause the formation of: carboxyhemoglobin, methemoglobin, cyanomethemoglobin, and sulfhemoglobin?

Answer 1

CO, nitrites, nitrites+CN, and sulfur gases (or more commonly, sulfanomide drugs), respectively

Question 2

What is the most common treatment for CO poisoning, in order to prevent lipid peroxidation and “late effects” of delayed neurologic sequelae?

Answer 2

Hyperbaric oxygen

Question 3

Which of the following ox-sat methods will give an accurate measurement of the oxygen saturation following CO poisoning: pulse oximetry, arterial blood gas via a co-oximeter, arterial blood gas via pO2 calculation?

Answer 3

Only the co-oximeter measurement will be accurate (the other measurements will be falsely normal)

Question 4

Name 3 drugs that can be given for cyanide poisoning.

Answer 4

Nitrites, sodium thiosulfate, and hydroxycobalamin

Question 5

Where does cyanide bind on the electron transport chain, inhibiting oxidative phosphorylation?

Answer 5

To cytochrome A3

Question 6

Which cyanide-poisoning therapy works by making normal hemoglobin into methemoglobin, which then outcompetes the cytochrome for CN molecules?

Answer 6

Nitrites

Question 7

Which cyanide-poisoning therapy works by enhancing the normal metabolism of cyanide via rhodanase?

Answer 7

Sodium thiosulfate

Question 8

Which cyanide-poisoning therapy, usually given concurrently with sodium thiosulfate, works by directly binding up CN to form cyanocobalamin (B12)?

Answer 8

Hydroxycobalamin

Question 9

Which cyanide-poisoning therapy should not be given in cases of concurrent CO poisoning, because it will cause a dangerous decrease in the concentration of normal circulating hemoglobin?

Answer 9

Nitrites

Question 10

What compound can be given to treat methemoglobinemia that is >20-30% or presents with symptoms?

Answer 10

Methylene blue

Question 11

In methemoglobinemia, which of following ox-sat methods will give an accurate measurement: pulse oximetry, arterial blood gas via a co-oximeter, arterial blood gas via pO2 calculation?

Answer 11

Only the co-oximeter measurement will be accurate (the pulse-ox will always be measured as around 87% no matter what the actual concentration is, while arterial blood gas calculation will be falsely normal)

Question 12

What dyshemoglobinemia therapy can cause side effects of hemolytic anemia, pain at the injection site, dyspnea, restlessness, apprehension, tremor, and precordial pain?

Answer 12

Methylene blue

Question 13

From what enzyme does methylene blue gain an electron, allowing it to directly reduce methemoglobin back to normal hemoglobin?

Answer 13

NADPH reductase