Tuesday, April 11, 2006

Suggestions for Review of Fitness to Dive Guidelines: ENT

We have had requests for a repeat of an editorial review of ENT fitness to dive guidelines, in our Ten Foot Stop for April 15, 2005.

Suggestions for Review of Fitness to Dive Guidelines: ENT

In our last newsletter we brought up the suggestion that guidelines placing restrictions on diving in certain conditions and with certain drugs might be too stringent and might possibly be either misapplied or archaic.

The suggestion has also been made that guidelines have been promulgated for military, commercial and professional divers based on conclusions drawn from naval diving medical officers for military personnel and that a different set of rules should be considered for sport and recreational divers. In addition, many recommendations in various guidelines are based on physician judgment and anecdotal experience and not on good clinical evidence. There is not a large body of evidence in support of many of the 'absolute' and 'relative' contraindications usually listed. However, it also can be stated that the same physical forces are acting on the same human body when anyone descends beneath the surface, and that immutable physical laws should apply across the board. This is certainly true but it is the strict application of rules without any 'wiggle room' that is vexing to many people.

In the final analysis for many of the restrictions, it is actually the amount of risk that an individual is willing to take in order to participate in sport diving. After reading my editorial in the last newsletter, Glen Egstrom, PhD wrote this about risk associated with diving:

"Scubadoc- I read your newsletter with the usual amount of stimulation. I feel that an old (1787) Ben Franklinism fits here very well. He observed “Having lived long I have observed many instances of being obliged by better information and for consideration to change opinions even on important subjects which I once thought right but found to be otherwise.” The evolutionary changes in the view of the relative levels of risk associated with diving often have the appearance of lowering levels of concern on the part of the medical and instructional communities of divers. I prefer to view it as a heightened appreciation for the nature of the risk vs. benefit evaluation. Risk assignment should be based upon objective, scientific analysis of a hazardous condition. The benefits, often less quantifiable, should be viewed in terms of physical as well as mental health aspects. The nature of the calculated risk should be clearly explained to the individual on the basis of the objective evidence. Most individuals, armed with specific knowledge about their fitness to dive and the risks placed in perspective, are likely to make good informed decisions. For those who do not pay attention, they will probably continue to let their minds make appointments that their bodies cannot keep. As is their right as an individual.

It has always been easier to be arbitrary and overly restrictive than it has been to get good evidence for a balanced opinion. I personally have always felt that regular doses of hyperbaric “therapy” in the form of diving have provided benefits to my life that make the risks more than acceptable. Good luck on your project, it could be a real challenge! "

Revisiting the "Absolute Contraindications" to diving - as outlined by various organizations such as the RSTC and NOAA and copied by most of the certifying agencies, turns out to be a difficult project, as there are few studies to be found that back up their recommendations. Making the guidelines more lenient turns out to be just as difficult - again because there are few suggestions that can be based on evidence. Expert opinion and anecdotal evidence are generally the substantiating factors in making decisions about fitness to dive.

The obvious reasons why a person should not be allowed to dive are as follows:

* Disorders that lead to altered consciousness
* Disorders that inhibit the "natural evolution of Boyle's Law"
* Disorders that may lead to erratic and irresponsible behavior.

Here is the first system that we looked into, the ear, nose and throat - abnormalities in which can stop a person immediately from diving without any rules having been applied. Reviewed and commented upon by Allen Dekelboum, MD.

RSTC Absolute Contra-indications
• Monomeric TM
• Open TM perforation
• Tube myringotomy
• History of stapedectomy
• History of ossicular chain surgery
• History of inner ear surgery
• History of round window rupture
• Facial nerve paralysis secondary to barotrauma
• Inner ear disease other than presbycusis
• Uncorrected upper airway obstruction
• Laryngectomy or status post partial laryngectomy
• Tracheostomy
• Uncorrected laryngocele
• History of vestibular decompression sickness


NOAA Absolute Contra-indications

Inability to equalize pressure in the middle ear by auto-inflation. This may be due to a correctable problem such as polyps, nasal septal deviation or allergic rhinitis in which case the diver can be reevaluated after correction of the problem. In addition, this may be purely a training problem with technique and altering the clearing method might be all that's necessary. Nevertheless, one cannot and should not dive until this maneuver can be accomplished with ease.

Risks: Damaged middle and inner ear from barotrauma
Hearing loss
Severe balance problems

Perforation of the tympanic membrane. Until fully healed or successfully repaired with good Eustachian tube function, diving is contraindicated. Ease of equalization should never be ignored.
Risks: Water in the middle ear
Vertigo and possible drowning
Infection, middle and inner ear
Hearing loss.
Balance problems

Open, nonhealed perforation of the TM.
Risks: Water in the middle ear
Vertigo and possible drowning
Infection, middle and inner ear
Hearing loss.
Balance problems

Monomeric TM. A thinned out ear drum. Thickness differs in individuals. If the diver has good Eustachian tube function and can equalize easily - diving might be allowed. ENT consultation assessing the amount of pressure sustainable by the tympanic menbrane.
Risks: Perforation of ear drum
Water in middle ear with same risks as above.

Tympanoplasty, other than myringoplasty (Type I)
Tympanoplasty, Types II, III, IV all deal with tympanic membrane perforations as well as damaged ossicles. Goals are to have a dry ear, functioning Eustachian tubes, increased hearing, normal balance. Successful surgery with these factors present would not seem to be adverse to diving if ability to equalize is present. Discussion with surgeon about risk factors. Most chronic middle ear disease and mastoid disease is due to a poorly functioning Eustachian tube (ET). Correcting the middle ear disease, might not correct the ET problem.
Risks: Water in the middle ear
Vertigo and possible drowning
Infection, middle and inner ear
Hearing loss.
Balance problems

History of stapedectomy.
Most recently there have been good studies to show that stapedectomy is not the risk that was once thought. A study in the journal 'Otolaryngology, Head and Neck Surgery' in October, 2001 by Drs. House, Toh and Perez at the House Ear Clinic in Los Angeles concluded that stapedectomy does not appear to increase the risk of inner ear barotrauma in scuba and sky divers. These activities may be pursued with relative safety after stapes surgery, provided adequate eustachian tube function has been established. There had been the fear that the stapes implant would be pushed into the round window, damaging the inner ear. Those that agree with Dr. House are in the minority.

Otolaryngol Head Neck Surg 2001 Oct;125(4):356-60
Diving after stapedectomy: clinical experience and recommendations.
House JW, Toh EH, Perez A.
Clinical Studies Department, House Ear Clinic and Institute, 2100 West Third
Street, Los Angeles, CA 90057, USA.

History of inner ear surgery.
There are those who do not feel that successful inner ear surgery is a contra-indication to diving - given a functioning Eustachian tube and easy clearing of the middle ear. There should be hearing remaining that is normal or near normal. Not all who have repair of labyrinthine fistulae recover their hearing.
Status post laryngectomy or partial laryngectomy
Valid recommendation

History of vestibular decompression sickness - This probably is a valid recommendation. A study showed that only 28-32% of divers with IEDCS completely responded to hyperbaric treatment - indicating possible permanent damage to end organs such as the vestibule and cochlear. Farmer et al have demonstrated a near total return to baseline hearing if recompression is initiated immediately.
Inner Ear Decompression Sickness in Sport Compressed-Air Diving.
Laryngoscope. 111(5):851-856, May 2001.
Nachum, Zohar MD; Shupak, Avi MD; Spitzer, Orna MA; Sharoni, Zohara MA; Doweck, Ilana MD; Gordon, Carlos R. MD, DSc

Farmer JC, Thomas WG, Youngblood DB, et al. Inner ear decompression sickness. Laryngoscope 1976;86:1315-1327.

Radical mastoidectomy (posterior) involving the external canal is disqualifying. (Closed childhood OK). Dr. Dekelboum describes several commercial divers with mastoid cavities who went to work, waited for the vertigo to cease, after a few minutes, and performed their tasks, using prophylactic antibiotic ear drops after leaving the water.

Risks: Water in the middle ear
Vertigo and possible drowning
Infection, middle and inner ear
Hearing loss.
Balance problems

Meniere's disease is disqualifying, as well as surgical procedures designed to treat the condition. I can find no references backing this up except the unsupported statement that pressure worsens the condition. However, pressure is exerted in and on the body equally - not just on the endolymph. Meniere's is known to be initiated by vestibular stimulation and stress - certainly scuba diving can cause both of these - but so can many other things. Although risky, there are many Meniere's sufferers who dive. Diving is not recommended - unless one has a very reliable buddy who understands the risks.

Labyrinthitis This would be a situation that would not be permanent. Diving should certainly not be allowed in the acute phase.

Inner ear barotrauma and Perilymph fistula. No evidence that returning to diving is contra-indicated. http://tinyurl.com/4p468 . A repaired, asymptomatic fistula from round window rupture is not an automatic contra-indication to some diving medicine specialists. Parell et al have shown that if proper precautions are taken to maintain proper eustachian tube function, no further deterioration takes place in hearing if a patient returns to diving after experiencing cochlear IEBT.

Parell GJ, Becker GD. Inner ear barotrauma in scuba divers. A long-term follow-up after continued diving. Arch Otolaryngol Head Neck Surg 1993;119:455-457.

Dr. Allen Dekelboum states that he has the same feelings about this as to inner ear surgery. Although not published,he did an informal survey many years ago, involving the two largest series of those who treated inner ear barotrauma. All agreed that if there was usable hearing remaining in the ear and the patient took precautions to adequately equalize, aborting any dive when equalization failed, they would allow their patients to dive. Before I agreed with those surgeons, I always recommended that they not dive. They all did anyway and no one was hurt.

Cholesteatoma is disqualifying.

Cerumen impactions - remove before allowing to dive. This causes barotrauma of the external ear canal between the cerumen plug and the ear drum. Just remove the impactions. There is no need to remove non-impacted cerumen. Being too aggressive could lead to external otitis.

Stenosis or atresia of the ear canal- disqualifying. Narrowing of the external ear canal without blockage would be less risky and probably not adverse to diving.

Facial paralysis secondary to barotrauma. It is assumed that further diving would increase the risk of further barotrauma to the ear (the facial nerve passes through the wall of the ME.). http://tinyurl.com/4wle8 .
This does not seem acceptable that barotrauma will occur every time a person dives. Given ease of equalization this might be a situation that is not absolute and these patients could dive.

Tracheostomy, tracheostoma . Endotracheal tubes can be rigged to accept respirators - so it's possible that a scuba regulator could also be fitted to a tracheostomy. However, this is extremely risky and possibly fatal. It is not recommended that anyone with an external connection to the trachea dive.

Incompetent larynx due to surgery (Cannot close for valsalva maneuver). However, it might be possible to do other maneuvers that will open the ET.

Laryngocoele. This is an extremely rare occurrence and effects of the condition are variable. A large, fluid or pus filled sac obstructing the airway would certainly be a contra indication to scuba diving. An air filled sac with a narrow neck would be risky for obstruction and rupture due to barotrauma. A small asymptomatic laryngocoele would probably not cause a problem.

Congenital or Acquired hearing loss. It is assumed that this is because of the possibility of further hearing loss from a scuba diving accident. Whether or not to dive would depend upon the degree of hearing loss of each case. Total hearing loss in one ear confers the risk of complete deafness should the other ear be damaged due to a diving accident. When the risks are explained to the patient, they will make their own choice.