When someone has a breathing or cardiac emergency, supplying emergency oxygen can be crucial. During such an emergency, the amount of oxygen carried by the blood cells to the heart, brain, and the rest of the body is reduced, resulting in hypoxia. The air we breathe has about 21% oxygen. When you use a BVM, you deliver 21% oxygen to the patient. The amount of oxygen we exhale has about 16% oxygen. This is the amount of oxygen delivered when you use a face shield or resuscitation mask or give mouth-to-mouth or mouth-to-nose resuscitation. These percentages, while adequate for resuscitation, are not best for the hypoxic patient.
Emergency oxygen is often given in breathing or cardiac emergencies to increase the percentage of oxygen delivered to the patient. According to the US Food and Drug Administration (FDA), emergency oxygen units are available without prescription for first aid, provided they contain at least a 15-minute supply of oxygen and deliver a preset flow rate of at least 6 liters of oxygen per minute (LPM).
For drowning and suffocation, timely oxygen delivery may be more important than the use of an automated external defibrillator (AED). When a person suffocates, breathing stops but oxygen already in the blood stream continues to flow to the brain, heart, and other parts of the body until depleted. According to the American Red Cross on page 34 of its Lifeguarding Manual: “Due to inadequate oxygen to body tissues, cardiac arrest can… happen in as little as 3 minutes after submerging. Brain damage or death can occur within 4 to 6 minutes…. No two drownings are alike… [h]owever, in general, giving ventilations often will resuscitate the victim if they are given within 1½ to 2 minutes after submerging.” Giving a higher concentration of oxygen in such situations has obvious benefits.
Oxygen cylinders for first aid and personal use come in various sizes, many of which are portable and lightweight. For patients who need supplemental oxygen, portable cylinders allow chronic patients and rescuers to carry oxygen in bags or backpacks.In the United States, oxygen cylinders are often painted green and have a yellow diamond with the word “Oxygen.”
Portable oxygen cylinders have designations that identify them. The older designations used an alphabetical characters from “A” to “E” for different portable sizes. The current designations are more descriptive; they begin with “M,” for “medical,” followed by a number that signifies the cubic feet of oxygen that can be compressed into the cylinder when filled. Portable cylinders include M-2, M-4 (A), M-6 (B), M-7, M-9 (C), M-15 (D), and M-24 (E).
Each of these portable cylinders use the same type of oxygen regulator (type CGA 870). The CGA 870 regulator fits over the neck of the cylinder and is screwed into place with an O-ring gasket to perfect the seal. The regulator gauge will have the word “Oxygen” imprinted on its face, and it indicates the amount of oxygen in the cylinder in pounds per square inch (psi).
At the other end of the regulator is an oxygen outlet and a flowmeter that further controls the release of oxygen in liters per minute (lpm). With a variable-flow regulator, the oxygen can be released by lpm values from less than 1 to 15 or more.
Oxygen Delivery Devices
Delivery devices for oxygen are attached to the oxygen outlet on the regulator. Devices for oxygen therapy are designed to assist breathing or nonbreathing patients. In addition, these devices give different concentrations of oxygen, all above the oxygen concentration we inhale from the surrounding air. For example:
- Nasal cannulae can deliver oxygen to breathing patients only at 1 to 6 LPM (a concentration of 24% to 44%)
- Resuscitation masks with oxygen inlets can deliver oxygen to both breathing and nonbreathing patients at 6 to 15 LPM (25% to 55% concentration)
- Non-rebreather masks can deliver oxygen to breathing patients only at 10–15 LPM (up to 90% concentration)
- BVMs can deliver oxygen to breathing or nonbreathing patients at 15+ LPM (90%+ concentration)