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Pharm Unit 2 > Dyshemoglobinemias > Flashcards

Dyshemoglobinemias Flashcards

1
Q

Name four places CO binds in the body.

A
  1. binds Hgb - shifts oxygen dissociation curve, decreases 2,3-BPG
  2. binds myoglobin - myocardial tox.
  3. binds mitochondrial cytochrome oxidase - inhibits cellular respiration
  4. displaces NO from platelets - forms peroxynitrites
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2
Q

Which symptoms of acute CO effects are mild, moderate, severe?
chest pain, SOB on exertion, HA, coma, seizures, dysrhythmias, N/V, blurred vision, tachycardia, tachypnea, MI, ischemia, hypotension, dizziness, nyonecrosis, ataxia, cognitive deficits, skin bullae

A

mild - HA, N/V, dizziness
moderate - chest pain, blurred vision, SOB on exertion, tachycardia, tachypnea, cognitive deficits, myonecrosis, ataxia
severe - seizures, coma, dysrhythmias, hypotension, MI, ischemia, skin bullae

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3
Q

What are the late/chronic effects of CO?

A

cognitive dysfunction, dementia, psychosis, amnesia, parkinsonism, apraxia, peripheral neuropathy, incontinence

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4
Q

How long after CO exposure will late effects manifest?

A

2-40 days later

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5
Q

What is believed to be the theory behind late CO effects?

A

reperfusion injury - delayed lipid peroxidation

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6
Q

Who is at greatest risk for late CO effects? Adult or child? Associated acute symptoms?

A

adult over 30 who had a loss of consciousness

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7
Q

How will pulse ox read in CO poisoning?

A

falsely normal - carboxyHgb read as oxyHgb

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8
Q

How will an ABG read in CO poisoning?

A

co-oximeter - appropriate

calculation - falsely normal because pO2 normal

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9
Q

What is the appropriate treatment for CO poisoning?

A

ABCs (airway, breathing, circulations)
oxygen - shortens CO T1/2
consider hyperbaric O2 - shortens CO T1/2 further; prevents lipid peroxidation and neurologic sequelae

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10
Q

When are people exposed to cyanide?

A

jewelers, electroplating (mucus membrane or po exposure)

mostly - house fires

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11
Q

How does CN cause toxicity?

A

binds cytochrome A3 in ETC - no ATP!!

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12
Q

How does a CN patient differ from CO poisoning?

A

won’t be responding to supportive care, ABCs

lactate >10 associated with CN poisoning

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13
Q

What are the two components of the antidote for CN?

A

sodium thiosulfate and hydroxocobalamin (Vit B12a)

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14
Q

What is the MOA of sodium thiosulfate in CN poisoning?

A

enhances normal metabolism of CN through rhodenase enzyme

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15
Q

What is the MOA of hydroxocobalamin in CN poisoning?

A

binds with cyanide to make cyanocobalamin (Vit B12)

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16
Q

When should CN antidote be given?

A

any smoke inhalation victim not responding to supportive care and O2 therapy;
and any intentional CN exposure

17
Q

What is methemoglobin?

A

heme iron is oxidized to ferric (Fe+3) form

18
Q

What four ways is methemoglobin normally reduced back to normal? Which one can be exploited for therapeutic use?

A
  1. NADH met-Hb Reductase
  2. Ascorbate
  3. Glutathione
  4. NADPH met-Hb Reductase - can be increased with methylene blue
19
Q

What drugs and toxins lead to methemoglobin production?

A

Drugs - nitrites, nitrates in infants, sulfonamides, phenazopyridine, dapsone, local anesthetics

Toxins - nitrites, nitrates in infants, aniline dye, potassium chlorate, diarrheal illness in infants (makes nitrites)

20
Q

How does methemoglobin cause toxicity?

A

shifts O2 dissociation curve left - less willing to give up O2 in tissues

21
Q

Match the percent met-Hb to the symptoms:
0-10, 10-20, 20-50, >50, >70

apparent cyanosis; coma and death; dizziness, fatigue, HA, exertional SOB; asymptomatic; lethargy/stupor

A 
0-10 asymptomatic
10-20 apparent cyanosis
20-50 dizziness, fatigue, HA, exertional SOB
>50 lethargy/stupor
>70 coma and death
22
Q

What is the antidote for methemoglobin?

A

methylene blue

23
Q

What’s the MOA for methylene blue in treating methemoglobinemia?

A

cofactor for NADPH reductase; gains electrons and donates them to methemoglobin

24
Q

What is the indication for using methylene blue?

A

met-Hb >20-30% or symptoms

25
Q

Side effects of methylene blue?

A

hemolytic anemia, pain at injection site, higher doses can cause dyspnea, restlessness, tremor, precordial pain, apprehension

26
Q

What are the possible reasons for someone to not respond to methylene blue treatment?

A

hemoglobin M disease; G6PD deficiency (lack generation of NADPH); CL salts inactivating G6PD; sulfhemoglobinemia; wrong diagnosis

27
Q

What will the pulse ox of someone with methemoglobinemia look like?

A

Fall rapidly into the high 80s

28
Q

ABG results of patient with methemoglobinemia?

A

co-oximeter - appropriate

calculation - falsely normal because pO2 not affected

29
Q

Is sulfhemoglobinemia more or less dangerous than methemoglobinemia?

A

more benign - doesn’t cause cyanosis as easily

treatment is supportive only

Pharm Unit 2 (10 decks)

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