Should I breathe quickly during safety stop

[Skydiver1]

Is it better to breathe rapidly to get more oxygen into the blood and get rid of all that nitrogen.

Or is it better to just breathe as normal at a constant rate.

I normally have loads of gas left on my back during the safety stop so was wondering which is optimal from a safety point of view.

Thank you.

 

[Jax]

What did your OW class say?

 

[Skydiver1]

What did your OW class say?

Many things

 

[Jax]

Perhaps you could talk to your instructor, or check your book again, for the part about breathing, CO2 retention, and what triggers the breathing cycle. Good info to keep in mind, especially if you are in a stressful environment.

 

[Jax]

Just quickly fishing in Google, here is a good link: Natural Athletes - S.C.U.B.A. Tips: Control Breathing

Being a newb, I'm not qualified to say. Everything I read says steady, deep, slow breaths, exhaling completely, inhaling completely.

 

[boulderjohn]

The rate at which you breathe makes almost no difference in the rate at which you on-gas or off-gas. It is the gradient between the partial pressure in the air in your lungs and in your blood, and the difference rapid breathing makes is inconsequential.

 

[Zen1300]

The article refers to regulator when it should refer to BC.

I am also a new diver and was taught complete inhale/exhale. Changes in the breathe pattern were done to make minor adjustments to depth when not swimming.

I would assume at the safety stop your focus would be on maintaining position through full breaths (at least where an anchor line is not assisting).


Sent from my SCH-I510 using Tapatalk

 

[Jax]

May I recommend a book on the physiology of off-gassing?

Amazon.com: Deco for Divers (9781905492077): Mark Powell: Books

 

[DevonDiver]

+1 for 'Deco for Divers' by Mark Powell. It should be compulsory reading at AOW level.

@Skydiver1: The release of nitrogen from body tissues into the cardio-vascular system and cross-over through the lungs for exhalation is determined by 2 factors:

1) The relative pressure differential between the pressure of the nitrogen saturated in the body and the surrounding/ambient pressure exerted on the body.

2) The 'speed' of the tissues in which nitrogen has been absorbed; where the saturation of nitrogen into progressively 'slower' tissues is determined by depth/pressure and time.

Once the nitrogen has passed from the body into the air-spaces of the lungs, it is easily removed through normal respiration. No special effort in breathing will make a noticeable difference.

I am also a new diver and was taught complete inhale/exhale. Changes in the breathe pattern were done to make minor adjustments to depth when not swimming.

The total lung volume of human lungs is typically between 4 - 6l

A minimum volume (functional residual capacity) cannot be emptied (1.8-2.2l) as the lungs cannot be 'fully' emptied to the point of collapse.

The maximum volume of the lungs at full, forced inhalation is called the vital capacity.

Average 'relaxed' human breathing only exchanges approx 0.5l of air from the lungs. This is called the tidal volume.

Full inhalation and exhalation should allow a maximum air exchange in the range between the functional residual capacity (min) and vital capacity (max). This can range between 3.1 - 4.8l depending on the individuals' maximum lung volume.

Very few people could manage any sustained breathing at the maximum variances of their lungs for anything but a very short period. Typical 'full' breathing is more likely to be only around 1-2 litres of increased/decreased volume.

Safety stops: Divers should attain neutral buoyancy to conduct stops. Neutral buoyancy is achieved by correct inflation of the BCD. Divers should not maintain buoyancy for protracted periods using lung control. When you wish to hover, use breathing to initially maintain a constant depth, if you have to, but then aim to immediately achieve neutral buoyancy through correct manipulation of your BCD volume. If you don't do this, then any distraction (mask flood/clear, OOA etc etc) will immediately result in you losing buoyancy control (and probably sinking again).

 

[Bubbletrubble]

@Skydiver1: Breathe "normally," with a normal depth/volume at a relatively constant rate and rhythm. Some people favor slightly deeper-than-normal yoga-style breathing. That should be OK provided that you aren't skip-breathing.

You're thinking about this scenario in terms of nitrogen off-gassing, but the exchange of other gases is occurring simultaneously across the alveolar membrane. If you change your breathing rate, you'll be affecting exchange of all the other gases as well.

Theoretically, one might be able to increase the respiration rate enough to accelerate nitrogen off-gassing (via partial pressure gradient), but this would also increase carbon dioxide exchange -- perhaps to a greater extent (based on partial pressure gradient). Increasing the respiration rate to an extreme would result in hyperventilation, leading to hypocapnia (low concentration of carbon dioxide in the blood) and respiratory alkalosis (high blood pH). Such changes in blood chemistry can lead to cerebral vasoconstriction, which would induce light-headedness, dizziness, headache, fainting (possibly), etc. Not good.