Dyshemoglobinemias

Question 1

How is CO produced in the environment?

Answer 1

Incomplete combustion of carbon containing material

Question 2

What is the route of entry for CO into the body? What consequences does this have?

Answer 2

CO gains entry and exit through direct respiration which means increased respiratory rate equals increased dose

Question 3

What is the only situation when CO will rise after removal from the source?

Answer 3

Methylene chloride exposure

Question 4

name 4 physiological effects of CO in the body

Answer 4

1 Binds to hemoglobin (200-250x affinity of O2) shifts O2 curve to the left, also decreases BPG which further shifts to the left
2 Binds to myoglobulin causing direct cardiotoxicity
3 binds to mitochondrial cytochrome oxidase and inhibits respiration
4 displaces NO from platelets and forms peroxynitrites resulting in free radical mediated damage though to produce CNS symptoms

Question 5

What are mild acute CO symptoms?

Answer 5

HA, N/V, dizziness

Question 6

What are moderate acute CO symptoms?

Answer 6

chest pain, blurred vission, dyspnea, tachycardia, tachypnea, cognitive deficits, myonecrosis, ataxia

Question 7

What are severe acute CO symptoms?

Answer 7

Seizures, coma, dysrythmias, hypotension, MI/ischemia, skin bullae

Question 8

What are late/chronic CO symptoms?

Answer 8

Cognitive dysfunction
dementia, psychosis, amnesia
Parkinsonianism, paralysis chorea, cortical blindness

Question 9

What is thought to be the mechanism of late/chronic symptoms?

Answer 9

delayed lipid peroxidation caused by reperfusion when WBCs adhere to brain microvasculature.

Question 10

What is the major indicator for late/chronic effects of CO poisoning?

Answer 10

Loss of consciousness at the scene (CO level doesnt matter at this point)

Question 11

What will O2 sat tests show with CO poisoning?

Answer 11

Pulse Ox - falsely normal bc carboxyheme shows same as oxyheme
co-ox appropriate
calculation falsely normal bc pO2 is not affected

Question 12

What is the main treatment from CO poisoning and how does it help?

Answer 12

Hyperbaric oxygen. Shortens half life of CO and possibly prevent lipid peroxidation.

Question 13

What is the standard pressure for HBO in CO treatment?

Answer 13

2.8 ATM

Question 14

What are indications for HBO treatment is CO exposure?

Answer 14

loss of consciousness, GCS < 15, CO >10%, myocardial ischemia, ventricular dysrhythmias, neurologic signs

Question 15

What brain findings are seen in CO poisoning?

Answer 15

bilateral low density in areas of globus pallidus, putamen, and caudate nuclei

Question 16

How does CN fuck your shit up?

Answer 16

Binds to Cytochrome A3 on ETC

Question 17

What are 3 treatments fort CN poisoning?

Answer 17

1 Nitrites for methemoglobinemia- attract CN away from Fe 3+ on CA3 to Fe3+ on metheme. [CANNOT DO THIS WITH CONCURRENT CO POISONING]
2 Sodium thiosulfate - enhances natural metabolism
3 hydroxycobalamin binds with CN to make cyanocobalamin

Question 18

How can you recognize CN poisoning?

Answer 18

Lactate >10mM

pt doesnt respond to supportive care. if CO they will get better with O2, with CN they will not.

Question 19

What is the major cause of formationof methemoglobin?

Answer 19

nitrates

Question 20

How does methemoglobin affect binding curve?

Answer 20

left shift

Question 21

What do O2 sat tests show with methemoglobin formation?

Answer 21

pulse ox- falsely and aberrantly lowered into high 80s
co-ox appropriate
calculation- falsely normal because pO2 not affected.

Question 22

What is the specific antidote to methemoglobin?

Answer 22

methylene blue

Question 23

How does methylene blue work?

Answer 23

Cofactor for methemoglobin reductase, requires NADPH thus functioning G6PD

Question 24

When is methylene blue indicated?

Answer 24

methemoglobin >20-30%

Question 25

What are some reasons why someone wouldnt responds to methylene blue treatment?

Answer 25

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

Question 26

How is sulfhemoglobinemia treated?

Answer 26

Supportive care only, little toxicity.