Judging a diver’s ability to handle the conditions at
hand is a tough call for a captain or crew member. Several
  Undercurrent readers have reported operators benching
divers due to medical conditions or physical limitations.
It’s unlikely that one would book a dive trip he doesn’t
think he can handle, but if a boat captain or divemaster
doesn’t think so, there can be a nasty disagreement, with
a few thousand diver dollars at stake.
One of our long time subscribers, whom we’ll call
  Mark, told us Captain Mike Lever barred him from diving
  on the Nautilus Explorer’s trip to Mexico’s Socorro Island
  in the Pacific. Mark had previously made a successful trip
  on the Nautilus Explorer in Alaska’s challenging waters,
  and was booked for back-to-back trips to Socorro. Lever
  said, “Diving at Socorro is not for folks who aren’t in good
  physical condition.”  
We exchanged letters and emails with both parties
  and their accounts differ significantly; however there are
  important points to be made. Lever says when people
  signed up he asked if they have any medical conditions
  worth noting. When the trip was under way, he also asked
  if participants had any medical conditions they wished to
  discuss in private. In neither case did Mark come forward.
  On the second day, when Mark demanded help lifting a 2-
  kg camera and housing, Lever said “it set off alarm bells.”
  He asked to see Mark’s medical clearance. In Mark’s file,
  besides a letter from a physician’s assistant clearing him to
  dive, Lever discovered that Mark was taking medications
  for a variety of maladies. Lever maintains that Mark had
  not disclosed these problems when asked whether he had
  any special medical requirements, conditions or history of
  diving injuries.  
However, says Mark, “my request for help with lifting
  my equipment due to a back injury I had sustained nearly
  two years ago caused him to conclude that I was unfit to
  dive . . . I had been on six live-aboard trips in the interim,
  had done over 200 dives since the accident.”  
Mike and Mark then called Marks’s physician, who hadn’t signed off on Marks’s letter of clearance and didn’t
know much about diving medicine. Lever asked the doc
to discuss Mark’s conditions with Diver’s Alert Network
(DAN). After talking to DAN, says Lever, the physician
declined to clear Mark for diving, so Lever insisted
that Mark sit out the rest of the Socorro dives. But he
arranged an appointment for Mark with the hyperbaric
chamber doctors in port. Lever claims that, when confronted
about his medical nondisclosure, Mark said, “If
I tell you or any other operator about my medical problems,
you won’t let me dive.”
Lever allowed Mark to undertake rebreather training
  on the second trip in the company of a divemaster, but
  no deeper than 60 fsw. Mark was frustrated because he’d
  also planned to make open circuit dives with his camera,
  which he couldn’t use while training on the rebreather.  
Lever refused to give Mark a refund, though he had
  logged only four dives on the first Socorro trip. He did
  refund deposits for the three June trips he had booked.  
  
    | “If I tell you or any other operator about my medical problems, you
 won’t let me dive”
 | 
Lever told Undercurrent he believes he acted both in
  Mark’s best interest and that of his other passengers. A
  refund “didn’t enter my mind,” says Lever, because Mark
  “had lied to us and had ample opportunity to tell us
  about his medical challenges.” Mark filled a berth on the
  boat that could have gone to another paying customer.  
And Mark, an extremely experienced diver, does concede
  that, “Lever is right. He is the Captain. He can stop
  everyone on the boat from diving for any reason at all.”  
Glen Fritzler, owner of Truth Aquatics in Santa
  Barbara, CA, which operates three live-aboards, has a different
  point of view. “Although no one in my organization
  prefers to deal with diver emergencies,” says Fritzler, “I
  cannot condone keeping someone out of the water who
  could ‘potentially’ be a problem. It’s a fine line and it
  turns your hair gray, but it’s something we have come to
  live with. Diving is a unique activity where someone can
  really escape and I feel that your limits have to be decided
  by you and no one else. As an operator I simply pray that
  the individuals make the right choices.”  
Judgments are often subjective, and therefore difficult
  to defend. Take the situation witnessed by Liam Gowers
  (Rockwall, TX) while diving out of Bud ’n Mary’s Marina
  in Islamorada, FL. After a 100-ft. wreck dive, the instructor
  of a group of advanced students informed a pupil that
  he had showed symptoms of nitrogen narcosis and recommended
  that he sit out the next dive. Gowers says, “If
  the instructor suspected narcosis during the dive, it was
  negligent of him to continue with a narc’ed student. He
  can’t keep his eye on a diver suffering from narcosis and
  five other divers simultaneously.” And, why does narcosis
  bench a diver the next time out, especially if he is in an
  advanced class? Should he not be learning to manage it?  
Certifying agencies, and some dive operators, especially
  in heavily regulated countries like Australia, insist
  that divers fill out medical questionnaires when booking
  classes or a dive trip. Such a form is downloadable at www.padi.com/english/common/courses/forms. Under the
  heading “Have you ever had or do you currently have…”
  it includes such seemingly innocuous conditions as frequent
  or severe attacks of hay fever or allergy, recurrent
  back problems, ulcers, and high blood pressure (with or
  without medication). Answer “Yes” to any of these, and
  you may be required to have a doctor fill out a multi-page
  form or provide a letter certifying that you’re okay to dive.
  If there are items you must check, then learn in advance
  what documentation a dive operator will require, otherwise
  you may find yourself benched for ailments that you
  don’t believe affect your diving.  
That’s what Ken Paff’s diabetic partner Martha does,
  after a Blue Bubbles instructor in Cozumel refused to
  allow her to dive after he saw her check her blood sugar
  level. “Although he was nasty about it,” says Paff, “his
  actions were actually in line with the guidelines of the
  agencies at that time.” Fortunately, they were able to get
  a letter of clearance from a doctor at a Cozumel chamber
  and Blue Bubbles allowed Martha to dive. She now carries
  a letter from her doctor, though few operators have
  requested to see it. “In the past decade,” Paff reports,
  “various agencies and operators have eliminated or lessened
  their prejudices against diabetics and perhaps other
  folks with medical disabilities. While the concerns with
  diving by people with type 1 diabetes are real, an absolute
  prohibition is certainly not.”  
Tell the Truth  
As Bret Gilliam pointed out in the March Undercurrent,
  some divers choose to falsify health information on dive
  operator applications. Occasionally, dive professionals
  even encourage the practice. During a Nitrox course at
  Buddy Dive in Bonaire, Jan Culbertson (Seattle, WA) saw
  how flawed the screening process can be. While filling
  out the PADI medical statement, one student answered
  “Yes” to the question “Have you ever had or do you currently
  have [a] history of diving accidents or decompression
  sickness?” Without discussing the diver’s history, the
  instructor told her she couldn’t take the course unless she
  changed her response to “No.” “So right there in front of
  the rest of the class,” reports Culbertson, “she changed
  her answer and she was allowed to enroll in the class.
  Didn’t seem like a very safe practice to me.”
Gilliam, the founder of Technical Diving International
and a dive travel leader for many years, concluded: “You
can bluff but that doesn’t help once you’re underwater.”
If something goes wrong and you’re found out, the best
that can happen is that you’ll get benched for the rest of
the trip. The worst is that you’ll never come back.
Dive medicine specialist Ernest Campbell, MD, focusing
  on dive training, states, “Failure to report risky preexisting
  medical problems would certainly be adverse to
  diving safety, not only to the student but to the instructor
  and others on a dive excursion.”  
The Prescription Drug Threat  
Joel Dovenbarger, vice president of Medical Services
  for Divers Alert Network (DAN), points out that few conditions
  are, by themselves, severe enough to bar someone
  from diving (seizure disorders being the main one). The
  problem lies in combinations of conditions, particularly
  when they are treated with combinations of medications.
  Dovenbarger notes that many central nervous system
  meds contain nitrogen, so “risk is relative to depth” for
  divers. He also points out that the most common side
  effects of drugs at depth are anxiety and panic.  
One of our writers has his own story. To sleep when he
  travels, at his doctor’s advice, he often takes a small dose
  of lorazapam. It’s actually an anti anxiety medicine that,
  he reports, doesn’t cause him to sleepwalk to the refrigerator.
  One morning he intentionally took a tab before
  a dive to see what effect it might have underwater. Below
  100 feet, he says, he felt as if he were on an acid trip, most
  likely a combination of the drug’s effect at four atmospheres
  and narcosis. “I had told my experienced companion
  what I was doing so we managed it, but an unsuspecting
  diver on the same drug might indeed panic.”  
Have Your Doc Call DAN  
In determining what degrees or combinations of
  conditions are safe for diving, Dovenbarger insists that a
  physician should decide, not an untrained individual (neither
  the diver nor a local dive operator). If you and your
  physician have questions, DAN will be happy to field a call
  from your physician to discuss the specifics of any situation
  or even to walk through the filling out of a medical
  questionnaire such as PADI’s.  
Like Gilliam, Dovenbarger urges divers to tell the truth
  on medical forms. Otherwise, if a health crisis occurs on
  a dive trip, in or out of the water, the victim may not get
  proper treatment. Remember the scene in “Something’s
  Gotta Give” when Jack Nicholson, suffering a heart attack,
  lies about using Viagra until his doctor warns him that the
  nitro in his drip could be fatal in combination with the
  drug? “Unless you start with the truth,” says Dovenbarger,
  “you won’t be happy with the outcome.”  
Some dive operators, especially live-aboards, offer
  medical questionnaires that must be completed to the
  satisfaction of the operator before the trip is confirmed.
  But others wait until the diver arrives, paid up. It would
  be useful if an industry-wide standard could be developed,
  but then not only would it require agencies to agree, it
  would require countries to agree. So, without a standard,
  a diver with any medical condition whatsoever needs to
  do his homework before committing to a dive operator,
  assess the situation and respond accordingly. Otherwise,
  as our friend Mark discovered, it could be a long trip,
  with little diving, and a lot of money down the drain.