Diving dangers for smokers

[sphyrnidus]

DAN | Mobile
In addition, we have to keep in mind the effects of tobacco smoking on the cardiovascular system, specifically vasoconstriction which decreases cardiovascular tissue perfusion. There is scientific evidence that this has an influence on the rate of nitrogen elimination after the dive. Again, this may increase the risk for a decompression injury. Furthermore, chronic marijuana smoking produces changes similar to tobacco smoking, and therefore it is very likely that it would have the same risks as tobacco smoking. Smoking marijuana immediately prior to diving means diving intoxicated and therefore represents a serious threat to diver safety. It is justified to advise against smoking and diving.

In this article from Dan I found this quote. While it doesn't give a depth limitation as the doctor gave TS, it is rather clear that the risk of DCS is higher in smokers. In this respect it does make sense to keep the nitrogen load lower and dive less deep. Or at least one should think about diving Nitrox on an air schedule.

 

[dreamdive]

DAN | Mobile
In addition, we have to keep in mind the effects of tobacco smoking on the cardiovascular system, specifically vasoconstriction which decreases cardiovascular tissue perfusion. There is scientific evidence that this has an influence on the rate of nitrogen elimination after the dive. Again, this may increase the risk for a decompression injury. Furthermore, chronic marijuana smoking produces changes similar to tobacco smoking, and therefore it is very likely that it would have the same risks as tobacco smoking. Smoking marijuana immediately prior to diving means diving intoxicated and therefore represents a serious threat to diver safety. It is justified to advise against smoking and diving.

In this article from Dan I found this quote. While it doesn't give a depth limitation as the doctor gave TS, it is rather clear that the risk of DCS is higher in smokers. In this respect it does make sense to keep the nitrogen load lower and dive less deep. Or at least one should think about diving Nitrox on an air schedule.

I noted the same in my article about smoking and diving. However, instead of giving a dive depth limitation perhaps an increase in safety stop time is more prudent.

 

[Hawkwood]

brnt999,

I know this does not answer your second question, but I guarantee that if you did require a doctor's certificate as a result of a "yes" answer to the questionnaire, none of the shops in Calgary would have accepted that certificate with "conditions" your doctor added.

 

[freewillie]

Few things about cigarettes and lungs. Lungs are a large network of small structures referred to as alveoli. The are the end space pockets of your lungs where CO2 gas off loads from the blood and oxygen loads into the blood. They are very thin allowing small capillary exchange of gases between venous blood and arterial blood. The tissues of the alveoli have an elastic tissue that allows them to expand and contract to move air in and out of your lungs. The tissue should be elastic enough to expand and have enough recoil to contract. So, as your chest moves out when you inhale the elastic recoil of the lung tissue allows the chest to contract as you exhale.

When you smoke a whole bunch of bad things happen to your lungs and your body. Specifically to TSandM's question your normally lose about 3 cm or less per year due to normal age related loss of elastic tissue. Living in California I'm probably losing little more per year due to our wonderful LA air quality. If you reach normal adult size in your early 20' and have a lung function of about 6 liters you should have some mild form of emphysema around the age of 90 if you live long enough. You won't actually develop overt symptoms of COPD (chronic obstructive lung disease - or smoker's lung) until your pulmonary function test decline to under 50% and usually closer to 40% before you complain of shortness of breath. That means you can lose the equivalent of one whole lung (50%) function due to smoking before you have symptoms. Smoking accelerates the loss of lung function so you present with COPD and symptoms at younger ages such as 65-70 years old than expected (if you expect to present closer to 90 years old.)

As the referenced articles also point out there is accelerated heart disease and atherosclerosis associated with cigarettes. So smokers who dive over age 50 are even more likely to have cardiac/heart problems while diving such as a heart attack.

One of the characteristics of COPD is that you have holes that form in the lung tissue due to the destruction of lung tissue from the smoke itself. These holes are referred to as blebs medically and are essentially air pockets in the lungs. Also, as the capillary tissues get destroyed you have problems no only with oxygen gas exchange but build up of CO2 - carbon dioxide. So the two biggest concerns with for divers with emphysema are expansion injuries from gas trapping in the blebs and carbon dioxide accumulation causing carbon dioxide narcosis. It also is associated with increase risk of nitrogen narcosis and DCI as well.

I use the "Sports Diving Medical" published by DAN as my medical reference for acceptable and disqualifying conditions for diving. In that book emphysema is considered a disqualifying medical condition.

Now, for the smokers here on Scubaboard that dive the real question is, "how much do you have to worry that you have emphysema from your smoking?" That is a very difficult question that has no answers here in a chat room. You can get a sense of damage from pulmonary function testing and from x rays or even CAT scans but they may miss patients with mild disease and are only obvious in patient with severe disease (and the patients with severe disease are likely not diving anyways - would get too short breath with even mild activity let alone diving.)

It then becomes a calculated risk. What makes the question difficult for doctors is that there is no accurate way to determine that risk on just Pulmonary function test and x rays. History helps in that if you are very fit and very active there should not be a big risk but you don't really know as the doctor (and for that matter the patient as well.) So at best you have only a minimal risk to you really shouldn't be diving at all. As for the doctor's limit of 60 feet I can't say that it based on a medical reference but may just be the doctor's personal comfort in certifying a patient for dive related activities.

 

[Octopusprime]

My guess is if the doctor was in Cozumel it was probably CYA'ing himself. He probably gets lots of checkup referrals. I would consult your doctor at home. There could have been something in the X-ray maybe not.

 

[brnt999]

My guess is if the doctor was in Cozumel it was probably CYA'ing himself. He probably gets lots of checkup referrals. I would consult your doctor at home. There could have been something in the X-ray maybe not.

I think you may be right that the 60 foot limit was the doctor CYA. A doctor in Cozumel is probably under some pressure to do what he can to support the dive industry which accounts for a fair chunk of the local economy. At the same time his professional credibility is on the line every time he signs one of those clearance forms. My impression was he took no pleasure he signing the form. Which leads to my second question. If a doctor signs a medical release form and the diver experiences a medical condition while diving, is the doctor liable?

 

[flots am]

I think you may be right that the 60 foot limit was the doctor CYA. A doctor in Cozumel is probably under some pressure to do what he can to support the dive industry which accounts for a fair chunk of the local economy. At the same time his professional credibility is on the line every time he signs one of those clearance forms. My impression was he took no pleasure he signing the form. Which leads to my second question. If a doctor signs a medical release form and the diver experiences a medical condition while diving, is the doctor liable?

The medical form instructions recommend that the diver have an exercise capacity of 13 METS (among other things)

I can pretty much guarantee that 80% of actual (not internet) vacation divers are not capable of sustaining 13 METs for the length of a dive. It's roughly equivalent to:

• Hiking up a 5% incline at 6 MPH wearing a 44 pound backpack.
• Ice Hockey
• Running a marathon

This is a much higher standard than actual SCUBA diving requires, however it's printed right on the form.

In an area with a functioning legal system, a good lawyer could throw pretty much any doctor who signs one, right under the bus.

In a place like Mexico, it's unlikely anything would happen.

Also, as I think more about the 60' limit, it does make sense because in Coz, it excludes the drift dives.

The only places I'm aware of that are within the 60' range, are very quiet, shallow and present a very small risk. If the diver takes off on an 80'+ drift dive and dies from a heart-attack, the doc can just shrug his shoulders.

 

[drbill]

I don't understand the doctor's limit on depth. However, I quit smoking 40 years ago. Had I not done so (one of the best decisions I've ever made), I probably wouldn't be diving as much today

 

[daniel1948]

The medical form instructions recommend that the diver have an exercise capacity of 13 METS (among other things)

I can pretty much guarantee that 80% of actual (not internet) vacation divers are not capable of sustaining 13 METs for the length of a dive. It's roughly equivalent to:

• Hiking up a 5% incline at 6 MPH wearing a 44 pound backpack.
• Ice Hockey
• Running a marathon

This is a much higher standard than actual SCUBA diving requires, however it's printed right on the form. <...snip...>

According to this page, 13 mets is the equivalent of running 13 km/hr, or about 7 1/2 minutes per mile. This is indeed something that many recreational scuba divers cannot do, but is a far cry from ten-minute miles up a 5% incline with a 44-pound backpack. Also, the form does not specify for how long the diver must be able to maintain a rate of 13 METS. I believe they mean the diver reaches 13 METS on the last stage of a stress test. This test increases speed and incline in stages, but the patient is not wearing a backpack.

In short, I think 13 METS is not as difficult to achieve as your examples suggest, especially since it refers to (I believe) the last stage of the test, and not (as your examples suggest) a long-term sustained activity. The form does not say the diver must be able to sustain 13 METS for the length of a dive, just that the diver must be able to score 13 METS on a stress test.

 

[flots am]

According to this page, 13 mets is the equivalent of running 13 km/hr, or about 7 1/2 minutes per mile. This is indeed something that many recreational scuba divers cannot do, but is a far cry from ten-minute miles up a 5% incline with a 44-pound backpack.

It's here on page 556: Metabolic equivalents (METS) in exercise testing, exercise prescription, and evaluation of functional capacity - Jett[] - 2009 - Clinical Cardiology - Wiley Online Library