Hurricane spray not benign

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medivac

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Just a reminder (or an alert to those who didn't know), that hurricane spray/benzocaine can cause your patient to turn gray and their blood to turn maroon-brown :eek: and you to have an involuntary butt spasm :scared:

Heard a code blue called to our obs unit the other day. RT was with me later on for an extubation in the ICU, turned to me and said, doc, you gotta see this abg result! Pt was having procedure down in obs (don't know what) and had gotten some hurricane spray. Soon after he turned a lovely ashen color and the SaO2 monitor was reading in the 70's. ABG with PO2 of 333, S02 in 80's. Methemoglobin in 50's. RT reported his blood was the darkest he'd ever seen. Quick lit search shows multiple case reports of topical benzocaine leading to methemoglobinemia. FDA has an alert about same, with recommendations of ONLY 1-2 sprays lasting no more than one second. I don't know about y'all, but I've seen our ENT peeps being much more liberal than that for PTA aspirations and scopes.

So just something to park in your midbrain, along with the tx=> supportive/high 02->methylene blue 1-2 mg/kg->hyperbaric 02 depending on severity
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If the person using the stuff did not know that this was a possible side effect, then maybe they shouldnt be using it. Just sayin'... :rolleyes:
 
davbrucas said:
If the person using the stuff did not know that this was a possible side effect, then maybe they shouldnt be using it. Just sayin'... :rolleyes:
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There are side effects with everything, QT prolongation with fluoroquinolones for example. Do you get an ECG everytime you rx Cipro? ;)

I didn't know about hurricaine spray and methemoglobinemia. now I do, even though they are case reports. its what makes SDN special.:D
 
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Surprising that the pulse ox was in the 70's. Either there was a concurrent hypoxia, or the machine's reading was wrong. Because methemoglobinemia should cause your pulse ox to sit right around 85%. In fact, when you see cyanosis with a pulse ox of about 85% that doesn't change with supplemental O2, it should make you think methemoglobinemia.
 
medivac said:
Just a reminder (or an alert to those who didn't know), that hurricane spray/benzocaine can cause your patient to turn gray and their blood to turn maroon-brown :eek: and you to have an involuntary butt spasm :scared:

Heard a code blue called to our obs unit the other day. RT was with me later on for an extubation in the ICU, turned to me and said, doc, you gotta see this abg result! Pt was having procedure down in obs (don't know what) and had gotten some hurricane spray. Soon after he turned a lovely ashen color and the SaO2 monitor was reading in the 70's. ABG with PO2 of 333, S02 in 80's. Methemoglobin in 50's. RT reported his blood was the darkest he'd ever seen. Quick lit search shows multiple case reports of topical benzocaine leading to methemoglobinemia. FDA has an alert about same, with recommendations of ONLY 1-2 sprays lasting no more than one second. I don't know about y'all, but I've seen our ENT peeps being much more liberal than that for PTA aspirations and scopes.

So just something to park in your midbrain, along with the tx=> supportive/high 02->methylene blue 1-2 mg/kg->hyperbaric 02 depending on severity
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I listened to an audio digest CME lecture by Dr. LoVecchio (a toxicologist) and he mentioned this very thing. GI guy's use benzocaine before a scopes and this very scenario happens more than you would think.
 
One of the Chicago-area EMS systems uses benzocaine spray as part of our drug-assisted intubation protocol. Maybe six or seven months ago, they put a leaflet on the box of benzocaine urging us to use as little as possible due to possible methemoglobinemia. Interesting.
 
This is something that anesthesia providers are very familiar with but have little experience with. In fact, most of us really don't want to ever experience it and I would get that only a few of us have actually seen it. We tend to stay away from the spray and use other methods of topicalization instead. Interesting presentation.
 
I had a case of methemoglobinemia a few months ago, from Pulmonology doing a bronch... pretty typical presenttion with nothing od about it. Benzocaine -> blue -> methylene blue!

Q
 
Anyone know why the spray causes methemoglobinemia? You know, biochemically.....Yes, I am a first year.
 
swoop said:
Anyone know why the spray causes methemoglobinemia? You know, biochemically.....Yes, I am a first year.
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Basically, the nitrate or nitrite causes some form of oxidative stress, which oxidizes the iron in hemoglobin from a 2+ to a 3+. As for an exact pathway, that is still somewhat poorly understood. While nitrates can cause methemoglobinemia in vitro, they likely go through a biotransformation to nitrite before causing methgb. The aromatic amines/nitrates, such as analine and benzocaine, do not cause methgb in vitro, so there is clearly some sort of secondary process occurring.

As for treatment, I've found that less is often more. Since you are taking advantage of the alternative Methgb reduction pathway and methylene blue is recycled utilizing NADPH, you don't need to be hyperaggressive. Methylene blue itself can cause methgb. Methylene blue needs to be reduced to leukomethylene blue in order to reduce the Fe(3+), so if there is too much methylene blue and not enough NADPH, it uses the Fe(2+) as its electron doner. I usually give 1 mg/kg of lean body wieght and have yet to have a treatment failure (n=4). Plus, I can always give more.

The real goal in treating methgb is to make the patient asymptomatics, not turn all the methgb to hgb. Most people will be asymptomatic with a Methgb less than 30%. Even with a chronic disease, most people will be asymptomatic with a level of less than 20%. When treating, I shoot for getting the level below 20% and abatement of symptoms. Most of the time it goes to less than 5% fairly rapidly and is 1% or less by morning.

The grey zone is the 20-30%. Some people I know will treat based on the number alone, while others will not. Greater than 30% and treatment is usually indicated, unless there is a contraindication (like G6PD).

As a side note, the "hypoxia" seen on pulse ox and blood gas is not real. It is an artifact of how these things are measured. The patient's oxygen delivery (DO2) is usually stll fine, they just have a functional anemia. I've seen a few people flip out when the pulse ox reads 80% and the blood gas says something similar, but they don't bother to note that the SaO2 is 90 on room air and the patient is feeling fine. Having a seen a few, I've become comfortable just leaving them alone if they feel fine, with a mid 20s methgb, even if they look like a Smurf.
 
BADMD said:
Basically, the nitrate or nitrite causes some form of oxidative stress, which oxidizes the iron in hemoglobin from a 2+ to a 3+. As for an exact pathway, that is still somewhat poorly understood. While nitrates can cause methemoglobinemia in vitro, they likely go through a biotransformation to nitrite before causing methgb. The aromatic amines/nitrates, such as analine and benzocaine, do not cause methgb in vitro, so there is clearly some sort of secondary process occurring.

As for treatment, I've found that less is often more. Since you are taking advantage of the alternative Methgb reduction pathway and methylene blue is recycled utilizing NADPH, you don't need to be hyperaggressive. Methylene blue itself can cause methgb. Methylene blue needs to be reduced to leukomethylene blue in order to reduce the Fe(3+), so if there is too much methylene blue and not enough NADPH, it uses the Fe(2+) as its electron doner...
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Holy Crap, there's a new chief nerd on the EM board:D
Does that mean I can retire?

So, is one of your points basically that MetHgb level of say 20% is no more physiologically significant than a fairly acute drop in your hct of 20%(minus the volume effect) and that the remaining 80% of norma Hgb should continue to provide normal oxygen delivery? Or, is their some sort of nonlinear competitive effect of MetHgb on regular Hgb. It might be useful for the students to contrast this with CO poisoning.
 
Thanks, great explanation. I did not realize benzocaine was an aromatic nitrate...makes perfect sense. (If I ever learn anything useful I wouldn't mind being a resident dork.)
 
ERMudPhud said:
Holy Crap, there's a new chief nerd on the EM board:D
Does that mean I can retire?
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Once we get out of the Toxicology relm, I'm pretty useless. ;)

ERMudPhud said:
So, is one of your points basically that MetHgb level of say 20% is no more physiologically significant than a fairly acute drop in your hct of 20%(minus the volume effect) and that the remaining 80% of norma Hgb should continue to provide normal oxygen delivery? Or, is their some sort of nonlinear competitive effect of MetHgb on regular Hgb. It might be useful for the students to contrast this with CO poisoning.
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I typically think of Methgb as being a functional anemia. I'm sure someone who knows more than I can lay on the subtle details, but yes. The only thing that I know of where Methgb competes with hemoglobin for something, is cyanide, where, fortunately, it wins out.

I hadn't really contrasted it to CO poisoning, but it is an great comparison. CO does more than just prevent oxygen delivery by binding hemoglobin. It is kind of funny that many indications for HBO is level triggered, even when we know level x time is far more significant than the level alone.
 
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DrQuinn said:
I had a case of methemoglobinemia a few months ago, from Pulmonology doing a bronch... pretty typical presenttion with nothing od about it. Benzocaine -> blue -> methylene blue!

Q
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Don't forget the IV Vitamin C....


The gas passers/surgeons where I'm at put lidocaine 1% in a neb for a bronch. Never seen that before coming here, thought it was cool....
 
So to translate this to practice I routinely write "No more than 4 sprays" when I write for benzocaine. I write it for NGT insertions mainly. I have seen it left sitting at bedside for patients to use PRN for discomfort from their NGTs. That's a big no no.
 
more peds-land-ish, it's also associated with bad well water (nitrites/nitrates from fertilizer, chicken lots, etc)- if you live in an area with wells. there's also an inherited form if you live where there are "limited gene pools" (amish/menonite, etc)

--your friendly neighborhood recent peds board taking caveman
 
Not new but unlikely side effect, the effects are not immediate either. FYI
 
Cool new word- topicalization!

I've always been aware of this and think about it every time I spray the stuff. I don't know that I've ever used more than 2 seconds of it.
 
Some places have gotten the sprays that don't allow continuous spraying and locks out after 3 sprays so no one can get more than 3.
 
Count to "two one thousand" while imagining spraying - that's a lot of Hurricane. I'm with Active Duty, I don't think I use more than that very often, if ever.
 
I remember the day that we got a new glidescope while I was a resident. There was a line of other residents and nurses spraying their throats down and looking at their cords. We reminded them of the above and suddenly nobody wanted to see their cords anymore...
 
Man, 4 year old thread. There is some zombie revival going on.
 
Anyone ever hear of cepacol or other lozenges with benzocaine in them causing methemoglobinemia? Happened to think those are over the counter, but some people use them all day long for their sore throats.
 
There was recently a warning about Orajel use and methemoglobinemia, especially for kids.

"But it can't hurt me.. it is over the counter!!"
 
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