MRI-study on cardiac effects of packing

[Johan Andersson]

There is a new study on the effects of glossopharyngeal insufflation (packing) on cardiac function. The authors have used magnetic resonance imaging (MRI) to get anatomic images of the heart during breath holding at functional residual capacity (FRC), at total lung capacity (TLC), and with submaximal glossopharyngeal insufflation.

Cardiac Magnetic Resonance Imaging during Pulmonar... [Med Sci Sports Exerc. 2011] - PubMed result

I haven't read the full paper yet, but the authors end the abstract this way:
"The major finding of our study was that submaximal glossopharyngeal insufflation decreased cardiac output further albeit by a small amount compared to maximal inspiratory apnea. The response was not associated with severe biventricular dysfunction."

/Johan

 

[aris ioannidis]

thanks Johan... so, is packing safe or not?

 

[Johan Andersson]

Well, the possible dangers with packing have been discussed in earlier threads here on DB. See for instance:

http://forums.deeperblue.com/freedi...s-lung-injury-trained-breath-hold-divers.html
http://forums.deeperblue.com/freedi...pharyngeal-insufflation-cardiac-function.html
http://forums.deeperblue.com/freediving-science/84029-packing-blackout.html

I think there could be some serious dangers associated with packing. There are a few case studies describing individuals that have experienced quite severe symptoms after packing. I am concerned about the risk for gas embolism with packing, a topic that we are currently investigating.

/Johan

 

[Jouskari]

Here is one "new" risk of packing:

Tracheamalasia

My divebuddy was aspiring to become a competetive freediver. He had already achived 200 m DYN, when he was starting to get a sensation of pressure in the throat on each dive. This got gradually worse for ~ 2 months. When he finally got to the doctor the diagnose was tracheamalasia. i.e. the soft tissues in the upper airways had streched due to the overpressure causing pain and pressure in surrounding tissues on inhale or pack dives.

 

[trux]

thanks Johan... so, is packing safe or not?

Well, the effect of packing on cardiac function is certainly the lesser important risk, so the study won't tell you anything about the risks of packing, apart from quantizing the effect on the probability of a packing blackout.

There are also some other previous studies showing the effect of packing on the cardiac output:
Heart rate responses during a breath-holding compe... [Int J Sports Med. 2005 Jul-Aug] - PubMed result
Cardiovascular aspects of glossopharyngeal insuffl... [Undersea Hyperb Med. 2007 Nov-Dec] - PubMed result
Effects of glossopharyngeal insufflation on cardiac function: an echocardiographic study in elite breath-hold divers

However, although we all know a packing blackout is certainly a possibility, the real risks are elsewhere, and were documented in several other studies as well as in the threads mentioned by Johan above. The studies document rather clearly that there are certain risks, and that they should not be taken too lightly.

If interested, there are numerous studies about packing listed here:
documents packing @ APNEA.cz

 

[Johan Andersson]

While some of the other possible risks with packing may seem more important, I would still like to bring up the case that we reported some time ago.
Asystole and increased serum myoglobin levels asso... [Clin Physiol Funct Imaging. 2009] - PubMed result

In that diver, packing caused a disturbance in cardiac function resulting in periods of asystole (cardiac arrest) during the period of "packing blackout", as well as increases in serum myoglobin. Increases in serum myoglobin is one of the markers used to indicate cardiac injury in various conditions such as myocardial infarcts, etc.

It was recently reported that "cardioinhibitory syncope" was more common than "low cardiac output syncope" following packing. I.e., in "cardioinhibitory syncope" an increase in parasympathetic stimulation of the heart inhibit cardiac function to the point of syncope.
Glossopharyngeal insufflation induces cardioinhibi... [Clin Auton Res. 2010] - PubMed result
It could be that it was an exceptionally strong parasympathetic stimulation (cardioinhibitory reflex) that caused the cardiac arrest in the case above.

With this information in mind, it should be noted that cardioinhibitory reflex cardiac arrest in certain cases could be lethal, at least in susceptible individuals.
Death caused by cardioinhibitory reflex cardiac ar... [Forensic Sci Int. 2011] - PubMed result

I'm not saying that this is common or the most important risk with packing, but I think it is a mechanism that has not been discussed that much. Still, you should be aware of this mechanism if you practice packing.

/Johan

 

[Andrew the fish]

Here is one "new" risk of packing:

Tracheamalasia

...he was starting to get a sensation of pressure in the throat on each dive. This got gradually worse for ~ 2 months. When he finally got to the doctor the diagnose was tracheamalasia. i.e. the soft tissues in the upper airways had streched due to the overpressure causing pain and pressure in surrounding tissues on inhale or pack dives.

Bingo! I had quite a few x-rays taken in last couple months, doctor's didn't find anything and I didn't connect it with breath holding. For a while I thought there is some kind of esophageal tumor down in my throat.

 

[efattah]

At least two people have suffered arterial gas embolism followed by a stroke, from packing. Dominque Ventzke of Germany, and Ken Kiriyama, both suffered embolism+stroke+paralysis from packing. Dominique had it in the pool, shortly after beginning a dynamic. Ken had it while doing dry packing on his bed.

So, is embolism+stroke+paralysis of half your body a good, safe thing?

No, not at all. Packing therefore is EXTREMELY dangerous and should only be done by those that understand the risks....

 

[Jouskari]

At least two people have suffered arterial gas embolism followed by a stroke, from packing. Dominque Ventzke of Germany, and Ken Kiriyama, both suffered embolism+stroke+paralysis from packing. Dominique had it in the pool, shortly after beginning a dynamic. Ken had it while doing dry packing on his bed.

So, is embolism+stroke+paralysis of half your body a good, safe thing?

No, not at all. Packing therefore is EXTREMELY dangerous and should only be done by those that understand the risks....

+ Here in the Nordic countries we also have one confirmed pack+stroke from sweden. Don´t know all the details, but it was a rather bad one what I´ve heard (ER and long recovery).

 

[Jouskari]

Bingo! I had quite a few x-rays taken in last couple months, doctor's didn't find anything and I didn't connect it with breath holding. For a while I thought there is some kind of esophageal tumor down in my throat.

I think that there might actually be very many of these around, but few report them as it doesn´t affect your normal life if you just hold back on diving. The recommendation was to stop diving on full inhale for two months and to never resume packing.

If packing cant be avoided the recommendation was to do it as little and seldom as often (it will stretch the tissues every time).

 

[aris ioannidis]

Eric, did not know that! Is Ken ok now? when did it happen?

how many packs you think are dangerous?

 

[efattah]

Eric, did not know that! Is Ken ok now? when did it happen?

how many packs you think are dangerous?

Dominique Ventzke had the problem in 2003, he was rushed to the hospital.

Ken had the problem this year (2011), I think in January. He made a full recovery.

 

[Johan Andersson]

At least two people have suffered arterial gas embolism followed by a stroke, from packing.

I would say the number is greater than two. I know of at least five more people experiencing symptoms that could be related to arterial gas embolism. Far from all cases have been described in the scientific literature, and therefore is not know in the medical/scientific community even though they may be known among some freedivers. Some of the cases I know of have been discussed in other threads here on DB.

Take away message:
Be careful with packing, and be aware that "post-packing symptoms" may indicate a quite serious situation. Also, freedivers must be constantly supervised by a buddy/safety diver (at least during STA/DYN/DNF where there is limited compresison of the lung volume due to the constant ambient pressure), because there have been cases where divers suddenly have lost motor function during diving (probably due to cerebral arterial gas embolism). In that situation you may be unable to reach the surface on your own, and require intervention by your buddy to be rescued.

/Johan

 

[pingshui]

First of all: I have no medical background, but have thought about the pros and cons of packing quite a lot.

As I understand, the above studies only focused on the immediate effects of packing, but what about the longterm damage it could cause? Could, for example, the increased pressure on arteries damage the cardiac valve?