Medical FAQs

Here's a list compiled over the years of commonly asked questions. The list was created by DAN MDs and represent specific, evidence-based recommendations our member should take into consideration.

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I have been invited to a diving weekend on El Hierro, Spain. The accommodation where the divers are staying however is at about 1000 mt altitude. There will be 2-3 dives per day, varying depths, all well within limits. What the minimum surface interval should be before ascending to the accommodation?
Be aware that a change of altitude post dive, in excess of approximately 700m is considered carrying the same risk as flying after diving. As your transition will be of 1000m then this applies to you.

The most prudent is to leave 24 hours before flying or going to high altitude, but the minimum guidelines established by DAN and the Undersea and Hyperbaric Medical Society for flying/altitude (Sheffield and Vann 2004) are:

  • A single dive within the no-decompression limits: 12 hours
  • Repetitive dives or multiple days of diving: 18 hours
  • Decompression dives (planned or unplanned): substantially greater than 18 hours

 

This means that, with 2-3 dives a day you would be required to wait at least 18 hours.
Since this seems impossible to do, you are strongly advised to either restrict your diving to a single dive daily, to permit yourself an adequate surface interval, or change accommodation.

During my last dive, I hit a sea urchin and the spines went in my thigh. I wasn't able to remove all of them so I just let it heal thinking they would just fall off but, until now, the spines are still inside and sometimes my thigh swells up. Can you please let me know what I can do?
If the spines are only small fragments then the body will eventually absorb them.

If they are large then it would be best to go to a doctor to remove them as otherwise they will cause a foreign body granuloma which, although not a problem of health concern, may leave a noticeable ‘bump’ in the skin.

Four days ago I came into contact with a jellyfish in the Mediterranean Sea. At the pharmacy I was advised to use Flubason 0.25%, desoximetasone skin cream, but it doens't seem to do much in terms of relieving irritation and itchiness. Is there something I can do to help the healing process?
The normal therapy, in such cases, is always and mainly based on the use of local cortisone-based ointments or creams, and in addition, on the use of antibiotic preparations if there's the risk of an infection, but this does not seem to exist in your case.

It is quite common for the itching and discomfort to last for a few days, in spite of the cure. If it is too annoying, you could ask your doctor to prescribe a cortisone-based ointment with a higher concentration, and for the itchiness, you might consider (obviously only on prescription) an anesthetic cream for local use (xylocaine or lidocaine based).

When trying to provide rescue breaths in the water to an injured diver, why can’t I use my spare regulator’s purge button? That seems easier to me than trying to manage a pocket mask
Using the purge button of a second-stage regulator has been proposed many times, but any advantage it may seem to offer does not outweigh the potential risks and complications. If the regulator mouthpiece is not already in the unconscious diver’s mouth, trying to replace it can be difficult and time consuming.

Without a good seal and a means to occlude the diver’s nostrils, any attempts to ventilate will be unsuccessful. Even if the mouthpiece can be successfully placed in the diver’s mouth there is a risk of it pushing the relaxed tongue to the back of the throat and blocking the airway.
If the regulator mouthpiece remained or was placed in the diver’s mouth without blocking the airway, the next challenge would be administering air.

Purge buttons do not have any true regulatory capability. They effectively override the second stage’s function of stepping down gas from intermediate pressure to ambient pressure and thereby deliver intermediate-pressure gas directly from the first stage.
Delivering breathing gas to the lungs at too high a pressure may overinflate them, potentially leading to serious injury.
If the diver’s airway is not maintained in an open position, the breathing gas delivered by the purge button could be forced into the stomach, causing gastric distention.
This places the diver at risk for regurgitation, which can further compromise the airway and lead to aspiration.

Delivering rescue breaths using a pocket mask or similar method provides tactile feedback via changes in pressure required to ventilate the lungs; supplying rescue breaths with the purge valve eliminates this important feedback. Using a regulator’s purge valve also precludes the option of supplementing the gas with 100 percent oxygen.
Rescue methods that are currently taught by dive-training agencies are the result of years of practical experience.
Purge valves were never designed to function as rescue equipment. When ventilating an injured diver, rely on established methods

I would like to know if deep stops are always recommended for recreational dives, if the depth of the deep stop must be half of the maximum depth reached or half of the maximum pressure reached, and if, for multi-day dives, it is always recommended to do this deep stop
The introduction of a deep stop at half of the maximum depth reached during recreational dives during the ascent phase seems to:
  • significantly decrease inert gas bubbles detected by a Doppler scan after a dive
  • reduce tension of inert gas in ‘fast’ tissues, which is an important fact to correlate with gas exchange happening in the spinal chord. 

Authors of scientific publications regarding this topic concluded that a deep stop can decrease the likelihood of suffering from decompression sickness.