Archive for the ‘Barotitis Media’ Category

BAROTRAUMA & DYSBARISMS #3

January 18, 2007

BAROTRAUMA:  (Boyle’s Law) DESCENT = compression of the gas.  (volume decreases by 1/2 every 33 fsw)
ASCENT   = expansion of the gas.      (volume increases by 2 every 33 fsw)
(fsw = feet of sea water)

Boyle’s Law – This is why it is an absolute rule that people with asthma cannot SCUBA dive!ASTHMA and SCUBA diving = death.
During the dive some of the air breathed in at depth gets trapped in the alveoli and bronchioles.
Then during ascent that trapped air will expand and burst the alveoli and bronchioles, resulting in burst lungs and DEATH.
         
DESCENT INJURIES:  “SQUEEZE INJURIES”
DESCENT = compression of the gas.  (volume decreases by 1/2 every 33 fsw)

MIDDLE EAR SQUEEZE:  “Barotitis media”
The Eustachian Tube that connects the middle ear to the sinuses is not venting properly.
This prevents the air pressure from the SCUBA tank from getting into the middle ear. 
As a result, there is more pressure outside then in, increasing the pressure against tympanic membrane.
This causes the tympanic membrane (TM) to be pushed inward, causing pain and bleeding of the TM.
Increased pressure in middle ear causes mucosal bleeding and edema of the TM and the middle ear tissues.
If the diver ignores the pain and continues to descend the pressure will increase and the tympanic membrane may rupture inward. 
Water then rushes into the middle ear causing severe vertigo as a result of caloric vestibular stimulation.
 
PREVENTION: 
Valsalva or Frenzel maneuver, to equalize the pressures between the sinuses and the middle ear.   
Long-acting Decongestants/Antihistamines used for 3 days prior to dive.
Inhaled Nasal Steroids used for 7 days prior to dive.

TREATMENT:  
STOP THE DESCENT and ASCEND to where it is pain free.
Decongestant/Antihistamine.
Monitor for onset of Otitis Media.

CONTRAINDICATIONS FOR A DIVE:
Perforated Tympanic Membrane
Sinusitis
Upper Respiratory Tract Infection
Asthma is an absolute contraindication to diving, ever.

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