Ear Barotrauma, on the way up or down?

[String]

That article doesnt deal with the possibility of lower threshold of O2 toxicity caused by it though (see DAN site).

Rather than papering over the cracks if you feel you need decongestant to dive safely or comfortably you really shouldnt be diving.

 

[fisherdvm]

I don't dive with nitrox, I am just a recreational diver and a physician who is concerned about the safety of the average diver... Here is another study:

1: Am J Emerg Med. 1998 May;16(3):262-4. Links
A double-blind comparison between oral pseudoephedrine and topical oxymetazoline in the prevention of barotrauma during air travel.Jones JS, Sheffield W, White LJ, Bloom MA.
Department of Emergency Medicine, Butterworth Hospital, Grand Rapids, MI, USA.

To determine the efficacy of two decongestants (oral pseudoephedrine versus topical oxymetazoline) in the prevention of middle ear barotrauma during air travel, 150 adult volunteers with a history of ear pain during air travel were entered into a randomized, double-blind study conducted at two commercial airports. Each subject received 120 mg pseudoephedrine, oxymetazoline hydrochloride (0.05%), or a double placebo (capsule and nasal spray) administered 30 minutes before flight departure. After arrival at their final destinations, volunteers were asked to complete a questionnaire and return it by mail to investigators. Questions included the intensity and duration of otologic symptoms experienced while flying and possible drug side effects. A total of 124 subjects completed the study; 41 received 120 mg of pseudoephedrine, 42 received oxymetazoline nasal spray, and 41 received a double placebo (capsule and nasal spray). The three treatment groups were similar with regard to age, sex, medical history, and flight profile. Symptoms of barotrauma were reported by 34% of those receiving pseudoephedrine versus 71% of the control group, for a relative risk reduction of 52% (95% confidence interval [CI] 33% to 71%). In contrast, 64% of the oxymetazoline group reported symptoms of barotrauma, for a relative risk reduction of 10% (95% CI, 3% to 17%). These results suggest that treatment with 120 mg pseudoephedrine at least 30 minutes before flying appears to decrease the incidence of barotrauma. Oxymetazoline nasal spray is little more effective than placebo in reducing ear pain and discomfort associated with changing ambient pressures.

 

[String]

Again doesnt address the O2 tox threshold.

Also, where did you read you cant tox on Nitrox-21?

 

[fisherdvm]

I personally would not recommend blindly on the use of pseudofed in diving. If you read my thread on my criticism of a "dive expert" physician who recommeded pseudofed on Scuba Diving magazine article, I thought that it was rather wreckless ....

I think the comment earlier about decongestant wearing out - certainly applies to pseudofed.... as its effect last only about 4 hours.

Unfortunately, I did not find any studies on long actining non-drowsy antihistamines like claritin or allegra. I believe these are relatively safe and quite effective for people with seasonal allergy.

I find it interesting that Afrin spray was no more effective than placebo... Perhaps it is too difficult to get it into the eustachian tube.... I hate that stuff with a vengence.... It is wicked on your throat if you tilt you head back to get the eustachian tube....

 

[fisherdvm]

Again doesnt address the O2 tox threshold.

Also, where did you read you cant tox on Nitrox-21?

Please explain to my lack of knowledge of nitrox.... What happens if I breath 21% oxygen at 3 ATM?? I've not done nitrox class...

 

[String]

To try to simplify what could be a long post.

High partial pressures of oxygen can eventually lead to CNS toxicity (convulsions etc)
Generally most agencies have accepted as > 1.6 as being a risk baseline.
There were some studies by DAN and universities that suggested the use of pseudo ephedrine decreased this threshold to a lower level thereby meaning a risk of toxicity at lower partial pressures of oxygen.

As nitrox is enriched in oxygen this is more of an issue if true.

Although i cant find it now i also read somewhere about pseudo-ephedrine having an effect on narcosis levels with some divers.

 

[fisherdvm]

As I understand, with compressed air, your MOD is like 150 to 200 ft. I have little desire to exceed 80 ft on my dives. I imagine my chance of getting oxygen toxicity is very low. But I don't use pseudofed.

Again, I have been a stout opponent of using pseudofed blindly in diving. My preference would still be a non drowsy antihistamine...

 

[Rick Inman]

Is that truly wierd or might it be that the fresh water is colder than any salt water you dive?

Yes and yes.

 

[WesTexDiver]

Most people will stop and ascend if their ear doesn't clear on the way down. But if you can clear on the way down, and not on the way up, that's where I think the problem is.

This would be true if people were smart, and used the thing between their ears. :shakehead

 

[Scuba-Jay]

Alright this has become slightly silly. Its my position that REVERSE SQUEEZE occurs MOST OFTEN when a diver is sick but chooses to take medications which then wear off during the dive........Someone disagree with that general statement??