Lung trauma

[DavidPT40]

Is there a rule of thumb that applies to lung overexpansion injuries? For instance, I heard that a man diving in a 6 foot deep pool took in a lungfull of air at a 6 foot depth, then came to the surface at which point his lungs ruptured.

Are lung injuries really this easily obtained? What are the easiest ways to prevent them?

Thanks
David

 

[deepblueme]

Yes.
Easier to have happen coming up in shallower depths.

Never hold your breath.

When I was a little diver long ago I was standing in a 10ft pool took a breath, held it and popped my co2 and rode it up and could feel my lungs expanding.

 

[Web Monkey]

Is there a rule of thumb that applies to lung overexpansion injuries? For instance, I heard that a man diving in a 6 foot deep pool took in a lungfull of air at a 6 foot depth, then came to the surface at which point his lungs ruptured.

Are lung injuries really this easily obtained? What are the easiest ways to prevent them?

Thanks
David

I beleive the smallest distance I've heard of is a couple of feet, but your lungs don't have a pressure rating, and I'd be really careful of playing games with them.

You never know what weak spots you have or where they are and destructive testing isn't your friend.

Terry

 

[DavidPT40]

Ok, good info. So does one need to be constantly exhaling as he ascends? Will exhaling small bubbles suffice?

 

[JohnW]

Ok, good info. So does one need to be constantly exhaling as he ascends? Will exhaling small bubbles suffice?

Constantly breathing(inhaling or exhaling) to keep the airway open. the don't hold your breathe rule is really that important.

 

[DandyDon]

Ok, good info. So does one need to be constantly exhaling as he ascends? Will exhaling small bubbles suffice?

Normal ascents are best done slowly and brething normally; emergency ascents are taught to be done like that - yes. As long as your airway is open to blow small bubbles, expanding air can escape. This will most certainly be covered in your first certification course.

 

[DavidPT40]

It was covered, briefly. My concern was the discrepancy between what I was taught (a nonchalant "blow some bubbles when you surface") vs what I read on scubaboard (someone dying after ascending a mere 6 feet with a lung full of air). The fact someone could die in a shallow pool scuba diving is also a concern to me.

 

[TSandM]

The most important thing is to allow expanding air volume a way to escape from the chest (that doesn't involve rupturing lung tissue to do so!) You are unlikely to build lung pressures high enough to do damage if you allow air to escape from your lungs during ascent. It's not necessary to actively exhale hard, just enough to permit the expansion to vent. If you're gently breathing (not holding your glottis closed) this will happen automatically.

The proportional pressure changes are greatest at shallow depths -- Going from 15 feet to the surface is a 33% decrease in pressure, whereas going from 75 to 60 feet is only a 10% reduction. So you are going to see the largest volume expansion in the shallow depths (which is why divers should pay proper respect to a slow ascent in the last ten feet).

And as far as dying in a pool goes, you can do that without ever being on scuba -- The fact is that underwater is not a place we can live. Scuba diving is sort of amazingly safe, when you think about how hostile the environment is, but it is not without hazards and part of the reason for taking certification classes is to learn what they are and how to minimize them.

 

[Dr Deco]

Hello readers:


There is no question that the human lung can expand when coming up from shallow depths. The diaphragm can be pushed into the abdominal cavity and the lungs expand far beyond their limit. The lungs rupture and gas can escape into the chest cavity or into the blood channels and eventually reaches the brain or spinal cord. With a full breath of air, it can occur at about one foot theoretically.

Two references below illustrate that expanding air can cause injury in a compressed air environment (ref 1) or underwater (ref 2).

Dr Deco :doctor:



References :book3:

[1] Cerebral arterial gas embolism in air force ground maintenance crew--
a report of two cases. Lee CT. Aviat Space Environ Med. 1999 Jul;70(7):698-700.

Two cases of cerebral arterial gas embolism (CAGE) occurred after a
decompression incident involving five maintenance crew during a cabin leakage
system test of a Hercules C-130 aircraft. During the incident, the cabin
pressure increased to 8 in Hg (203.2 mm Hg, 27 kPa) above atmospheric pressure
causing intense pain in the ears of all the crew inside. The system was rapidly depressurized
to ground level. After the incident, one of the crew reported
chest discomfort and fatigue. The next morning, he developed a sensation of
numbness in the left hand, with persistence of the earlier symptoms. A second
crewmember, who only experienced earache and heaviness in the head after the
incident, developed retrosternal chest discomfort, restlessness, fatigue and
numbness in his left hand the next morning. Both were subsequently referred
to a recompression facility 4 d after the incident. Examination by the Diving Medical
Officer on duty recorded left-sided hemianesthesia and Grade II middle ear
barotrauma as the only abnormalities in both cases. Chest X-rays did not reveal
any extra-alveolar gas. Diagnoses of Static Neurological Decompression Illness
were made and both patients recompressed on a RN 62 table. The first case
recovered fully after two treatments, and the second case after one treatment.
Magnetic resonance imaging (MRI) of the brain and bubble contrast
echocardiography performed on the first case 6 mo after the incident were
reported to be normal. The second case was lost to follow-up. Decompression
illness (DCI) generally occurs in occupational groups such as compressed air
workers, divers, aviators, and astronauts. This is believed to be the first
report of DCI occurring among aircraft's ground maintenance crew.


[2] Arterial gas embolism following a 1-meter ascent during helicopter escape
training: a case report. Benton PJ, Woodfine JD, Westwood PR. Aviat Space Environ Med. 1996 Jan;67(1):63-4.

We present the case of a helicopter pilot who suffered an arterial gas embolism
following instruction in the use of the Short Term Air Supply System (STASS) at
a depth of 1 m [3 feet] of water. This is believed to be the shallowest depth from which a case of arterial gas embolism
associated with the use of compressed air breathing apparatus has been reported.

 

[Gene_Hobbs]

Previous thread: http://www.scubaboard.com/showthread.php?t=176172

from my post there:
The effects of a raised intrapulmonary pressure on the lungs of fresh unchilled cadavers.
Malhotra and Wright, 1961
Royal Naval Physiological Laboritory, Alverstoke, Hants
The Journal of pathology and bacteriology
PubMed ID: 13765778

Following a series of 'burst lung' cases following Submarine escape drills, the RN decided to look at information on pressures in the lung. Given that this can not be done on live subjects, five fresh, unchilled cadavers were used. They repeated observations made by Polak and Adams (1932) that dogs with bound chests and abdomens could tolerate high intrathacheal pressures.

The cadavers used were from persons aged from 27 to 64 years. One was unbound, one had abdominal binding and the other three had both abdominal and thoracic binding. It was found that the lungs on the unbound and abdominal only bound cadavers ruptured at approximately the same time. Appox. 80 mm Hg. (keep in mind this is fresh cadavers and that any lung pathology will also make a difference)