LEARNING OBJECTIVE: Recognize breathing aids and their uses.

As a Hospital Corpsman, you should become familiar with the breathing aids that may be available to help you maintain an open airway and to restore breathing in emergency situations. Breathing aids include oxygen, artificial airways, bag-valve mask ventilator, pocket face mask, and suction devices.

USE OF OXYGEN (O2)
In an emergency situation, you will probably have a size E, 650-liter cylinder of oxygen available. The oxygen cylinder is usually fitted with a yoke-style pressure-reducing regulator, with gauges to show tank pressure and flow rate (adjustable from 0 to 15 liters per minute). A humidifier can be attached to the flowmeter nipple to help prevent tissue drying caused by the water-vapor-free oxygen. An oxygen line can be connected from the flowmeter nipple or humidifier to a number of oxygen delivery devices that will be discussed later.

When available, oxygen should be administered, as described below, to cardiac arrest patients and to self-ventilating patients who are unable to inhale enough oxygen to prevent hypoxia (oxygen deficiency). Hypoxia is characterized by tachycardia, nervousness, irritability, and finally cyanosis. It develops in a wide range of situations, including poisoning, shock, crushing chest injuries, cerebrospinal accidents, and heart attacks.

Oxygen must never be used near open flames since it supports burning. Oxygen cylinders must be handled carefully since they are potentially lethal missiles if punctured or broken.

ARTIFICIAL AIRWAYS
The oropharyngeal and nasopharyngeal airways are primarily used to keep the tongue from occluding (closing) the airway.

Oropharyngeal Airway
The oropharyngeal airway can be used only on unconscious victims because a conscious person will gag on it. This airway comes in various sizes for different age groups and is shaped to rest on the contour of the tongue and extend from the lips to the pharynx. Selecting the correct size oropharyngeal airway is very important to its effectiveness. An airway of proper size will extend from the corner of the patient's mouth to the tip of the earlobe on the same side of the patient's face.

One method of insertion is to depress the tongue with a tongue blade and slide the airway in. Another method is to insert the airway upside down into the victim's mouth; then rotate it 180 as it slides into the pharynx (fig. 4-20).

Nasopharyngeal Airway
The nasopharyngeal airway may be used on conscious victims since it is better tolerated because it generally does not stimulate the gag reflex. Since it is made of flexible material, it is designed to be lubricated and then gently passed up the nostril and down into the pharynx. If the airway meets an obstruction in one nostril, withdraw it and try to pass it up the other nostril. See figure 4-21 for proper insertion of the nasopharyngeal airway.

BAG-VALVE MASK VENTILATOR
The bag-valve mask ventilator (fig. 4-22) is designed to help ventilate an unconscious victim for long periods while delivering high concentrations of oxygen. This system can be useful in extended CPR attempts because, when using external cardiac compressions, the cardiac output is cut to 25 to 30 percent of the normal capacity, and artificial ventilation does not supply enough oxygen through the circulatory system to maintain life for a long period.

Various types of bag-valve-mask systems that come in both adult and pediatric sizes are in use in the Navy. Essentially, they consist of a self-filling ventilation bag, an oxygen reservoir, plastic face masks of various sizes, and tubing for connecting to an oxygen supply.

Figure 4-20.-The rotation method of inserting an oropharyngeal airway.

Figure 4-21.-Proper insertion of a nasopharyngeal airway.

Figure 4-22.-Bag-valve mask ventilator.

Limitations of the Bag-Valve Mask Ventilator

The bag-valve mask ventilator is difficult to use unless the user has had sufficient practice with it. It must not be used by inexperienced individuals. The system can be hard to clean and reassemble properly; the bagging hand can tire easily; and an airtight seal at the face is hard to maintain, especially if a single rescuer must also keep the airway open. In addition, the amount of air delivered to the victim is limited to the volume that the hand can displace from the bag (approximately 1 liter per compression).

Procedures for Operating the Bag-Valve Mask Ventilator

To use the bag-valve mask ventilator, hook the bag up to an oxygen supply and adjust the flow in the range of 10 to 15 liters per minute, depending on the desired concentration (15 liters per minute will deliver an oxygen concentration of 90 percent). After opening the airway or inserting an oropharyngeal airway, place the mask over the face and hold it firmly in position with the index finger and thumb, while keeping the jaw tilted upward with the remaining fingers (fig. 4-23). Use the other hand to compress the bag once every 5 seconds. Observe the chest for expansion. If none is observed, the face mask seal may not be airtight, the airway may be blocked, or some component of the bag-valve mask ventilator may be malfunctioning.