Too often, the oxygen tank in a general dentist`s office is given little attention — until a medical emergency.
Cynthia R. Biron, RDH
The most frequently used treatment in the management of medical emergencies is oxygen. Its effects are crucial. Breathing oxygen gives you a lift, improves blood-oxygen concentrations throughout the circulatory system, decreases the workload of the heart, and improves oxygen concentration at the alveolar level. It should be used routinely in emergency management.
Too often, the oxygen tank in a general dentist`s office is given little attention — until a medical emergency. The task of checking the oxygen tank weekly is sometimes neglected. Regulators can fail and the tank can leak. The consequences of such carelessness during an emergency could be disastrous.
Why is oxygen so important?
A healthy patient has normal respiration, good oxygen and carbon dioxide exchange, a normal heart rate and blood pressure, and adequate circulation. Adequate circulation allows blood to perfuse every cell of the body with nutrients and oxygen. The same circulation process carries away waste products and carbon dioxide. This process of perfusion keeps us alive and well. When perfusion is impaired, shock is the result, as cells die of starvation and toxic accumulation. Shock is the lack of perfusion, associated with low blood pressure due to loss of total peripheral resistance. The ABCs of basic life support teaches how to maintain the principles of perfusion.
The three components of the circulatory system consist of a working pump (the heart), a network of tubing (arteries, capillaries, and veins), and an adequate volume of fluid.
Different forms of shock can occur depending on its originating factor, including: insulin shock, anaphylactic shock, hypovolemic shock, neurogenic or psychogenic shock, septic shock, metabolic shock, and cardiogenic shock. All can interfere with the circulatory system by either causing the heart to stop pumping, the arteries and veins to expand in diameter and lose their resistance, or blood to pool in areas of the circulatory system.
A typical reaction for patients experiencing shock is the "flight or fight" response. An adrenaline surge increases the heart rate and blood pressure. This is known as compensating — the patient is holding on and fighting for life. When the vital signs fall, the patient is decompensating, or losing the life-fighting battle. An adult with normal blood pressure is entering a state of shock if their systolic blood pressure drops to 70 mm Hg.
The severity of shock, however, is measured by comparing the patient`s baseline vital signs with those taken during an emergency situation. A patient with a baseline blood pressure of 160/98 may seem to have adequate perfusion at 100/80. However, he or she is still decompensating, because the blood pressure has fallen below baseline.
The basic treatment for shock is to maintain the airway, provide supplemental oxygen, cover the patient to prevent loss of body heat, and position the patient to increase blood flow to the head.
Every office should have at least two Series E oxygen tanks, which can be held upright in a portable carriage. The oxygen in conjunction with nitrous oxide in each operatory is not sufficient to deliver oxygen to patients in the reception area or somewhere else in the office. A back-up tank is also a must, because one tank of oxygen may not last until EMS arrives.
The oxygen tank is constructed of steel or aluminum and contains compressed oxygen under 2,000 psi pressure. The tank is color-coded green to distinguish it from other cylinders of compressed gas. It has a yoke with a 5-pin index — a distinguishing feature that fits only gas specific delivery systems. Should someone mistakenly try to attach oxygen fittings to a nitrous oxide tank, they could not be attached, as the index system would not be compatible.
The pressure regulator — or reducing valve — fits the yoke of the oxygen tank. It reduces the pressure of oxygen flow from 2,000 psi to levels of 40-70 psi, a safe delivery for patients. Positive pressure devices, or demand valve resuscitators, deliver approximately 60 liters of oxygen per minute in short bursts. This is designed for delivering intermittent jets of oxygen to patients who are not spontaneously breathing. Patients who can breathe spontaneously require a lower flow rate of 4-15 liters per minute. This requires a low-flow regulator.
Most dental offices should use a combination pressure regulator on a portable series E tank. The combination pressure regulator permits delivery of oxygen at low-flow rates for medical emergencies and/or supplemental oxygen for asthmatic patients during treatment. This type of pressure regulator contains one spigot for positive pressure (demand valve) that overrides the low-flow regulator and delivers bursts of oxygen at 60 liters per minute. The combination pressure regulator also has another spigot for low-flow delivery at 4-15 liters per minute for spontaneously breathing patients. Each regulator contains a flow meter to control the rate of oxygen flow. Many dental offices do not have oxygen tanks with low flow regulators, since they are not familiar with them or the need for low delivery of oxygen in medical emergencies.
Oxygen delivery systems
Administering oxygen requires a delivery system. Not every delivery system is correct for every emergency. The nasal cannula delivers low to moderate amounts of oxygen to spontaneously breathing patients. It is made of vinyl tubing and has two prongs that are placed in the patient`s nose. The simple face mask delivers slightly higher concentrations of oxygen than the nasal cannula, but is not as easily tolerated.
The best system for delivering high concentrations of oxygen to spontaneously breathing patients is the nonrebreather mask. This system has a reservoir bag that fills with 100 percent oxygen. A one-way valve from the mask to the reservoir prevents exhaled air from diluting the oxygen concentration.
The bag-valve mask, commonly known as the Ambu-Bag, is used to ventilate patients during CPR and to assist ventilation in semi-conscious patients with respiratory depression. The bag-valve mask may be used in atmospheric air ventilation at 21 percent oxygen. It can also be connected to the oxygen tank to deliver concentrations of oxygen from 40-100 percent, depending on the valve system and reservoir bag setup. The demand valve has a push button lever attached to the face mask, and tubing that connects it to the positive pressure spigot. When the lever is pressed, a burst of oxygen is released at a very high flow rate (100-150 liters per minute). When the operator releases the lever, a preset pressure (40-50 mm Hg) is established and the flow ceases. This is a safety feature which prevents over-inflation of the lungs.
An artificial airway maintains an open airway while assisting ventilations or during rescue breathing. These airways only go far enough into the pharynx to hold the tongue away from the back of the throat and maintain the airway during oxygen resuscitation. The dentist or team member — who should be thoroughly trained before inserting an artificial airway — performs a gag reflex test to determine the level of consciousness. The patient`s eyelid is stroked with the index finger. If the eyelid responds with a flutter or any movement, a nasopharyngeal airway is used. This type of artificial airway is made of soft, pliable plastic and can be cut to size. The size used is usually equal to the diameter of the patient`s nostril, and should be as long as the distance between the nose and earlobe. The airway should be lubricated with a water- soluble lubricant. Petroleum jelly, which is combustible, should never be used. The nasopharyngeal airway should be inserted into the nostril along the natural curvature until the flange is against the nostril.
Deeply unconscious patients who do not respond to the gag reflex test require an oropharyngeal airway. The size used should equal the length from the corner of the mouth to the earlobe. An airway that is too large can close off the airway, or cause a laryngospasm. If too small, the airway will not be opened enough to allow sufficient air exchange. The oropharyngeal airway is inserted by hyperextending the patient`s head and opening the patient`s mouth using a cross finger technique. Insert it upside down toward the soft palate, then rotate 180 degrees to remove the tongue from the back of the throat.
Other methods of maintaining an airway, such as endotracheal intubation, should be reserved for the well-trained, well-practiced dentist, or emergency medical technicians.
EMT`s universally state, "When in doubt, deliver oxygen!" Don`t wait until a patient is in shock to deliver oxygen. Even a fainting warrants a low-flow delivery of oxygen by nasal cannula. Hyperventilation is the only emergency in which supplemental oxygen is contraindicated. Do not wait until an emergency to learn to operate or check your oxygen tank. Do it now!
Cynthia R. Biron, RDH, is chair of the dental hygiene program at Tallahassee Community College. She is also a certified emergency medical technician.
Laminate and affix the following to your office`s oxygen tank:
Oxygen tank operation
To turn on:
1. Attach oxygen delivery system to tank.
2. Turn key on top of tank in counter clockwise direction to open the flow of oxygen.
3. Read low flow regulator knob; turn in the direction the arrow indicates to increase or open. Many regulators are opposite of sink faucets, and open clockwise instead of counter clockwise.
4. Attach oxygen delivery system to patient.
To turn off:
1. Remove oxygen delivery system from patient.
2. Turn key on top of tank in clockwise direction to shut off flow of oxygen.
3. Turn the "Low Flow" regulator knob to "open" position to bleed oxygen from the system.
4. After bleeding, gently close the "Low Flow" regulator knob.
Safety precautions for oxygen use
(1) Never use combustibles in the presence of oxygen, including petroleum products, such as Vaseline.
(2) Do not store oxygen in temperatures over 120 degrees F.
(3) Never adjust the regulator with your body directly over the tank.
(4) Connect the tubing to the tank and adjust the regulator before placing the delivery system on the patient`s face.
(5) Do not deliver high concentrations of oxygen to patients with COPD (Chronic Obstructive Pulmonary Disease), as it may reduce their hypoxic drive, which is their only remaining stimulus to breathe.