LEARNING OBJECTIVE: Recognize breathing aids and their uses.
As a Hospital medical technician, 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.
The oropharyngeal and nasopharyngeal airways are primarily used to keep the tongue from occluding (closing) the 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 ofproper size will extend from the corner ofthe patientís mouth to the tip of the earlobe on the same side of the patientís 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 victimís mouth; then rotate it 180į as it slides into the pharynx (fig. 4-20).
Figure 4-20.óThe rotation method of inserting an oropharyngeal 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.
Figure 4-21.óProper insertion of a 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.
Figure 4-22.óBag-valve mask ventilator.
Most of the various types of bag-valve-mask systems come in both adult and pediatric sizes. 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.
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.
Figure 4-23.óBag-valve mask ventilator in use. pocket face mask.
POCKET FACE MASK
A pocket face mask designed with an oxygen-inlet flow valve for mouth-to-mask ventilation can be used to give oxygen-enriched artificial ventilation. Although a pocket face mask system cannot achieve oxygen concentrations as high as the bag-valve mask system, it has the advantages of providing greater air volume (up to 4 liters per breath) and of being much easier to use (since both hands are free to maintain the airway and keep the mask firmly in place). See figure 4-24. The pocket face mask also acts as a barrier device. It prevents the rescuer from coming in contact with the patientís body fluids and breath, which are possible sources of infection.
Figure 4-24.óProviding mouth-to-mask ventilations with
To use the pocket face mask, stand behind the head of the victim, and open the airway by tilting the head backward. Place the mask over the victimís face (for adults, the apex goes over the bridge of the nose; for infants, the apex fits over the chin, with the base resting on the bridge of the nose). Form an airtight seal between the mask and the face, and keep the airway open by pressing down on the mask with both thumbs while using the other fingers to lift the jaw up and back. Ventilate into the open chimney of the mask.
Oxygen can be added by hooking the valve up to an oxygen supply. Since the rescuerís breath dilutes the oxygen flow in artificial ventilation, adjust the flow rate to increase oxygen concentration. At 5 liters per minute, the oxygen concentration will be approximately 50 percent. At 15 liters per minute, this concentration will increase to 55 percent.
The mask has an elastic strap so it can be used on conscious, self-ventilating patients to increase oxygen concentration.
The patientís airway must be kept clear of foreign materials, blood, vomitus, and other secretions. Materials that remain in the airway may be forced into the trachea and eventually into the lungs. This will cause complications ranging from severe pneumonia to a complete airway obstruction. Use suction to remove such materials.
In the field, a Hospital medical technician may have access to a fixed (installed) suction unit or a portable suction device. Both types of suction devices are equipped with flexible tubing, suction tips and catheters, and a non-breakable collection container.
Maintenance of suction devices consists of testing the suction pressure regularly and cleaning the device after each use.
Before using a suction device, always test the apparatus. Once the suction pressure has been tested, attach a suction catheter or tip. Position the patient on his side, and open the patientís mouth. This position permits secretions to flow from the patientís mouth while suction is being delivered. Use caution in patients with suspected neck or spinal injuries. If the patient is fully and securely immobilized on a backboard, the backboard may be tilted to place the patient on his side. If you suspect such injuries but the patient is not immobilized, suction as best you can without turning the patient. Carefully insert the suction tip or catheter at the top of the throat (fig. 4-25). DO NOT push the tip down into the throat or into the larynx. Apply suction, but for no more than a few seconds, since supplemental oxygen or ventilations cease while suctioning, keeping oxygen from the patient. Suction may be repeated after a few breaths.
Figure 4-25.óProper insertion of suction tip.
A cricothyroidotomy, often called an emergency tracheotomy, consists of incising the cricothyroid membrane, which lies just beneath the skin between the thyroid cartilage and the cricoid cartilage. In most cases, the cricothyroid membrane can be easily located by hyperextending the neck so that the thyroid notch (Adamís apple) becomes prominent anteriorly. Identify the position of the thyroid notch with the index finger. This finger descends in the midline to the prominence of the cricoid cartilage. The depression of the cricothyroid membrane is identified above the superior margin of the cricoid cartilage (fig. 4-26). Make a small lateral incision at the base of the thyroid cartilage to expose the cricothyroid membrane. Excise this membrane (taking care not to go too deeply) and insert a small-bore air line into the trachea.
Figure 4-26.óAnatomical structures of the neck to identify the cricothyroid membrane.
An alternate method is to use a 12- to 16-gauge intercatheter. Locate the cricothyroid membrane as described above and insert the needle into the trachea. Immediately upon penetration of the cricothyroid membrane, thread the plastic catheter into the trachea and remove the needle. Then connect the catheter to an oxygen line for translaryngeal oxygenjet insufflation.
Do not attempt a cricothyroidotomy except as a last resort when other methods of opening the airway have been unsuccessful.