[Packing] Effects of glossopharyngeal insufflation on cardiac function

[trux]

I found a relatively recent physiological document by R. Potkin about lung packing, which I did not see referred to here on DB yet. It may interest some of you:

Effects of glossopharyngeal insufflation on cardiac function: an echocardiographic study in elite breath-hold divers -- Potkin et al. 103 (3): 823 -- Journal of Applied Physiology

The abstract from JAP:

Glossopharyngeal insufflation (GI), a technique used by breath-hold divers to increase lung volume and augment diving depth and duration, is associated with untoward hemodynamic consequences. To study the cardiac effects of GI, we performed transthoracic echocardiography, using the subcostal window, in five elite breath-hold divers at rest and during GI. During GI, heart rate increased in all divers (mean of 53 beats/min to a mean of 100 beats/min), and blood pressure fell dramatically (mean systolic, 112 to 52 mmHg; mean diastolic, 75 mmHg to nondetectable). GI induced a 46% decrease in mean left ventricular end-diastolic area, 70% decrease in left ventricular end-diastolic volume, 49% increase in mean right ventricular end-diastolic area, and 160% increase in mean right ventricular end-diastolic volume. GI also induced biventricular systolic dysfunction; left ventricular ejection fraction decreased from 0.60 to a mean of 0.30 (P = 0.012); right ventricular ejection fraction, from 0.75 to a mean of 0.39 (P < 0.001). Wall motion of both ventricles became significantly abnormal during GI; the most prominent left ventricular abnormalities involved hypokinesis or dyskinesis of the interventricular septum, while right ventricular wall motion abnormalities involved all visible segments. In two divers, the inferior vena cava dilated with the appearance of spontaneous contrast during GI, signaling increased right atrial pressure and central venous stasis. Hypotension during GI is associated with acute biventricular systolic dysfunction. The echocardiographic pattern of right ventricular systolic dysfunction is consistent with acute pressure overload, whereas concurrent left ventricular systolic dysfunction is likely due to ventricular interdependence.

I found it thanks to the RSS alerts I have set up on my website - yesterday I included also articles related to freediving from over 5,000 medical sources through the MedWorm RSS service. You can see the headlines on the home page - if you want to see just the medical links, enter "category:medical" into the search box, or use this link: category:medical @ APNEA.cz

There are now also some other medical articles about packing:
Transpulmonary pressures and lung mechanics with glossopharyngeal insufflation and exsufflation beyond normal lung volumes in competitive breath-hold divers
Pneumomediastinum after lung packing.
Features of glossopharyngeal breathing in breath-hold divers

and also many others anout other physiolgical apsectf of breath-hold diving.

If you want to stay informed whenever a new freediving related medical article appears on the list, you can subscribe to the RSS feed - RSS is a free service supported by practically all recent browsers and email readers, and can be set up to alert you whenever the RSS feed has a new item. You can configure and filter the messages in the way you want.

Side note: do not have fear, unlike what Pastor claimed in another thread I am not "trying to poach members from deeperblue to my site" - the RSS service has nothing to do with your attitude to visit DB, and it is completely free. I developed it out of passion, not to poach anyone anywhere. That's absolutely contradictory to the character of RSS - if you get an alert about a new article through RSS, you in fact do not even see that it comes from my website and won't be forced to visit it at all - the links point directly to the articles at the original sources (which I am not affiliated with in any way). So once you subscribe to the RSS feed, you will never need to visit APNEA.cz anymore (unless you want to) and will stay informed anyway. This is exactly why I set up the RSS function - just because I know people do not necessarily have time and appetite to visit my website frequently, but still may like to get information about new freediving articles or forum posts that appear on other places than they regularly visit.

 

[naiad]

Packing is something to be very careful with. I think it can be a useful technique and I sometimes do it myself, but it can have many physiological effects and is not something to be taken lightly. It does scare me to see newbies using heavy packing as a way of trying to improve their statics or dynamics.

 

[daveking]

A few words of wisdom there.

 

[trux]

There is a new study about packing that will appear in the January issue of the Aviation, Space, and Environmental Medicine magazine:

IngentaConnect Suspected Arterial Gas Embolism After Glossopharyngeal Insufflati...

Many competitive breath-hold divers employ the technique of glossopharyngeal insufflation in order to increase their lung gas volume for a dive. After a maximal inspiration, using the oral and pharyngeal muscles repeatedly, air in the mouth is compressed and forced into the lungs. Such overexpansion of the lungs is associated with a high transpulmonary pressure, which could possibly cause pulmonary barotrauma. Case Report: We report a case of transient neurological signs and symptoms occurring within 1 min after glossopharyngeal insufflation in a breath-hold diver. He complained of paresthesia of the right shoulder and a neurological exam revealed decreased sense of touch on the right side of the neck as compared to the left side. Motor function was normal. The course of events in this case is suggestive of arterial gas embolism. Discussion: Although the diver recovered completely within a few minutes, the perspective of a more serious insult raises concerns in using the glossopharyngeal insufflation technique. In addition to a neurological insult, damage to other organs of the body has to be considered. Both acute and long-term negative health effects are conceivable.

 

[Fitz-Clarke]

It should be pointed out that the presentation of symptoms described in this paper is also entirely consistent with cervical radiculopathy, i.e. mechanical nerve root irritation in the C4-5 region of the neck.

We certainly need to be vigilant of side effects from packing and to question its safety. But at the same time, the title of the article is going to lead to some readers to draw an unsupported conclusion that this was caused by cerebral air embolism, even though the authors do use the term “suspected”. The issue of central (brain) versus peripheral (nerve) etiology cannot be resolved here. Of note, isolated paresthesias without motor involvement are most commonly of peripheral nerve origin, as sensory fibres are found in the outer layer of peripheral nerves, and are therefore most prone to local mechanical injury.

No doubt the packing manoeuvre itself puts stresses on the soft tissues of the chest and neck, as well as obvious stresses on lung tissue that could be conducive to barotrauma. There is one documented case report of pneumomediastinum (air in the central chest outside the lung) after packing, and one of transient heart block (intense vagal response) caught on ECG resulting in brief loss of consciousness. There have been many more unreported incidences of chest pains and other weird symptoms after packing that were not investigated.

There is still much to be learned about the mechanics of this unnatural act of lung packing. I am sure we will occasionally see strange things happening around this manoeuvre in the future. It is good to see cases being reported, as any symptoms raise concern about possible serious causes that need to be considered.

 

[Johan Andersson]

It should be pointed out that the presentation of symptoms described in this paper is also entirely consistent with cervical radiculopathy, i.e. mechanical nerve root irritation in the C4-5 region of the neck.

Yes, certainly there may be other causes. However, a number of factors such as the time course of the signs and symptoms, the nature of the same, etc, made us conclude that arterial gas embolism was the most plausible cause.

It should also be noted that Lindholm et al reported neurological symptoms after glossopharyngeal insufflation that were attributed to cerebral arterial gas embolism.

Neurological symptoms after glossopharyngeal insufflation (lungpacking) in breath-hold divers suggesting cerebral arterial gas embolism

That is, even if our cases does not exclude other causes, arterial gas embolism should be considered as a possible cause for neurological signs and symptoms after packing.

/Johan