Three Letters Re: Welding Oxygen Versus Medical Oxygen

I write to you again as I pull another EMS duty shift. So far tonight I have had one EMS call and it was a “difficulty breathing” call. Our local law enforcement officers (LEOs) already had the patient on 15LPM. of 02 via non-rebreather mask (NRBM) before we got on scene. The LEOs tend to over inflate, so I titrated the flow down to 8LPM., which worked for the patient’s breathing pattern. I’m glad our LEOs are proactive, but this means that I don’t get a baseline Room Air (RA) 02 saturation for comparison and it does waste some O2 until I get there.

Hint: We use NRBMs on the rig because from this one type of mask you can make the other types simply by removing the circular rubber flap valves. The NRBM has one inspiration valve at the top of the bag inside the mask; and two other expiration valves outside the mask on each side of the nose. When you exhale, the side expiration valves open allowing exhaled air and CO2 to escape outside the mask. But when you inhale, these same valves close, and the inspiration valve opens, allowing 100% O2 to enter the mask from the inflated bag. Hence the name non-rebreather mask because the patient is not re-breathing his own exhaled air. There is no outside air entrainment (provided the mask has a good seal).

1) If you take the same NRBM mask and remove one or both of the expiration valves from the side of the nose, you now have a partial rebreather mask, since when the patient inhales, 100% O2 from the bag is mixed with room air from the removed side valve port.

2) If you take both side valves off, and replace the bag O2 port with the straight line O2 port (that is included in the NRBM package), you now have a simple mask.

3) Here’s another trick, if you take the straight line O2 port off the mask, and replace it with the bottom medicine cup of a nebulizer, you have a aerosol mask for administering nebulized medications like albuterol sulfate.

As more air entrainment is allowed, the overall O2 percentage decreases from the 100% @ 8LPM. – 10LPM. of the NRBM to approximately 28% @ 2LPM. O2 of the nasal cannula. It doesn’t mean your wasting O2 by using a nasal cannula, (since it uses a lower flow rate) your just choosing the best modality to meet the patients need. Some chronic Chronic Obstructive Pulmonary Disease (COPD) patients breathing drive can actually be suppressed with too much O2 over a period of time.

(I’ve got to go, just got paged for an “Alcohol Overdose”).

Now I’m back again. The overdose call went okay. But I’m reminded that masks are also good for combative, spitting, or TB patients (Mask the patient and yourself) But on a sad note I found out that the patient I transported three hours ago with difficulty breathing died of respiratory arrest in the ER. She didn’t seem that bad, but she had a DNR order and the family requested she not be intubated. I volunteer for this.

Regarding O2 itself. Almost all O2 manufacturers use the Air Liquefaction method to make compressed O2 gas. The method is written on the side of the cylinder. This is why you will see large stand tanks of Liquid Oxygen (LOX) at the gas vendors’ sites. The oxygen that boils off the LOX is piped through a manifold system to fill the cylinders usually on a cascade system. So although O2 USP has the same basic source as industrial gases, it’s specified., handled, distributed and tracked differently. O2 USP has FDA mandated lot numbers to facilitate product recalls. These lot numbers are tracked all the way to the patient.

During the day I’m a Home Medical Equipment Technician in the respiratory department of a major hospital. We jokingly call the hospital room console the “magic” wall since compressed air, power, suction, O2, etc. is right there. But the fact that O2 is flowing through a humidifier bottle doesn’t instantly change it to medical O2 as the previous supplier quote asserts. It just adds humidity, and then really only at flow rates over 3LPM. Water bottles are mandated in the hospital setting, but not in the home setting. Oxygen is a natural drying agent. We do however use extra dry grades of O2 USP 99.995% and Nitrogen to calibrate our O2 analyzers.

A note on carbon monoxide poisoning. If the patient presents with the classic cherry red complexion, they are too far gone for any O2 to do much good. The carbon monoxide molecule binds something like 600 times more readily to the hemoglobin in the blood than O2, and has to be forced out by O2 in a hyperbaric oxygen chamber. Under double atmospheric pressure even the plasma in the blood carries oxygen. (Which might be one reason our Pre-Flood forefathers could run so far and not become weary.) – Steve P., EMT in Wisconsin


Mr. Rawles:
This is in regard to the oxygen discussion. I don’t know the slightest thing about the sources of oxygen, but as a nurse, I thought I would share a little bit about administration of oxygen. The following is straight from my Medical-Surgical Nursing textbook

” Indications for use: …Oxygen is usually administered to treat hypoxemia (decreased oxygen levels in blood) caused by respiratory disorders such as COPD, pulmonary hypertension, cor pulmonale, pneumonia, atelectasis (lung collapse), lung cancer, and pulmonary emboli; cardiovascular disorders such as myocardial infarction, dysrhythmias, angina pectoris, and cardiogenic shock; central nervous system disorders such as overdose of opioids, head injury, and sleep apnea. …..
-Oxygen toxicity- may result from prolonged exposure to a high level of oxygen. High levels of oxygen…..can lead to acute respiratory distress syndrome….All levels above 50% and used for longer than 24 hours should be considered potentially toxic. Levels of 40% and below may be regarded as relatively nontoxic and may not result in development of significant oxygen toxicity if exposure period is short.”

In other words, high levels of oxygen (100% via rebreather/non-rebreather mask) is ideal for emergency situations, but not more than 24 hours!! After stabilization of initial symptoms, it is best to go to a lower oxygen percent, usually 2-3 LPM (for a delivery of 21 to 30 percent oxygen). Of course, these guidelines are designed for medical professionals who can monitor the PaO2 and SpO2 so unless you have a pulse ox[imeter] at home, you’re going to be going with best guess. Watch for breathing difficulties such as trouble breathing, rapid breathing, cough, restlessness.
So, in summary, high oxygen to deal with the immediate emergency, then switch to low oxygen after stabilization or before 24 hours pass. I am a recent graduate, so anybody with more experience please feel free to jump in with any corrections.