Section Four Oxygen Therapy
PROCEDURE 25 General Principles of Oxygen Therapy and Oxygen Delivery Devices
PROCEDURE 26 Application and Removal of Oxygen Tank Regulators
PROCEDURE 27 Noninvasive Assisted Ventilation
PROCEDURE 25 General Principles of Oxygen Therapy and Oxygen Delivery Devices
CONTRAINDICATIONS AND CAUTIONS
1. In ill or injured patients, O2 is never contraindicated. Insufficient O2 administration may lead to hypoxia, which is a significant risk to the patient. Hypoxia may lead to cardiac arrhythmias and may damage tissues and organs. Supplemental O2 should be delivered to maintain an O2 saturation by pulse oximetry (SpO2) of greater than 90%. Administering additional O2, once the hemoglobin has fully saturated (SpO2 99% to 100%), increases the risk of toxic effects.
2. Oxygen-induced hypoventilation, from suppression of the hypoxic respiratory drive, may occur in a small set of patients. Administration of O2 to these patients may result in hypoventilation, further hypercapnia, and possibly hypoxia and apnea. This class of patients; often with underlying COPD, cystic fibrosis, sedation from medications for procedures, neuromuscular disease, morbid obesity, and extensive previous chest disease, requires more aggressive monitoring of their respiratory status during O2 delivery. Oxygen therapy should be titrated to maintain an SpO2 between 90% and 92% in these patients. If hypoxia persists, then invasive or noninvasive mechanical ventilation may be necessary.
3. A significant physical hazard of O2 therapy is fire. Oxygen supports combustion, and smoking should not be permitted anywhere O2 is being used. Spark producing appliances and volatile or flammable substances should also be removed from the area. Patients may need to be searched to ensure that they do not have any matches or lighters.
4. Absorption atelectasis may occur with use of high concentrations of O2. The usually more abundant nitrogen gas is “washed out” of the alveolus with breathing of high O2 concentrations. When the O2 is absorbed, the alveolus may collapse, further worsening the ability to oxygenate and ventilate the patient (Pierce, 2007).
5. Exposure of lung tissue to high O2 concentrations can lead to pathologic changes in the tissue. After only a few hours of exposure to high O2 levels (generally an FiO2 greater than 0.5) mucus clearance from the lung is depressed. More prolonged exposure may lead to changes that are similar to acute respiratory distress syndrome (ARDS). The lowest FiO2 capable of creating sufficient SpO2 should be used in an attempt to avoid O2 toxicity (Pierce, 2007).
6. Oxygen masks may impede care in patients with facial burns or trauma or who need frequent nursing care to the facial area. Gastric tubes may interfere with obtaining an adequate mask seal.
7. Aspiration is a potential hazard when an O2 delivery mask is in use. Elevating the head of the bed may reduce this risk.
8. Oxygen concentration delivery is highly variable, and factors such as O2 flow rate, ventilatory rate and depth, mask seal, and anatomic dead space all contribute to this variability (Table 25-1).
9. To deliver high O2 concentrations, masks must have a tight seal. This tight seal may be uncomfortable and irritating to the skin.
10. Masks may interfere with patients’ speech and must be removed for patients to eat meals.
11. All O2 delivery devices must be monitored to ensure they are functioning correctly and delivering the desired concentrations of O2.
EQUIPMENT
PROCEDURAL STEPS
1. Attach flowmeter or regulator to O2 source.
2. Attach the nut and tailpiece to the flowmeter. If humidified O2 is required, attach the humidifier to the flowmeter. Humidification is not required for short-term use.
3. Attach the flared vinyl tip of the O2 tubing to the tailpiece or humidifier.
4. Adjust the O2 to the flow rate as directed by equipment recommendations to deliver the prescribed amount of O2. The float ball on the flowmeter should be positioned so that the flow rate line is in the middle of the ball.
5. Check to see that O2 is flowing through the cannula or mask.
6. For nonrebreather masks, the reservoir must be filled with O2 before it is applied to the patient. When using an O2 mask with a reservoir bag, adjust the flow rate so that the bag does not collapse, even with a deep inspiration. These masks require a tight seal in order to deliver the highest concentration of oxygen.
7. Place the cannula prongs into the nares or apply the mask to the face. Oxygen masks have a malleable metal nose strip that can be adjusted for a better and more comfortable fit. Monitor to ensure that the mask side ports do not become blocked.
8. Padding straps with gauze or cotton may prevent irritation or discomfort.
9. If humidification is being used, periodically check and drain tubing of excess water as needed.
AGE-SPECIFIC CONSIDERATIONS
1. Allow an alert child to maintain a position of comfort.
2. Allow parents or caregivers to remain in the room with the child. Allow the parent or caregiver to hold the child if not contraindicated by patient condition.
3. Introduce O2 delivery devices in a nonthreatening manner. A parent or caregiver may hold the O2 delivery device to decrease the child’s anxiety.
4. If a child becomes too upset by the O2 delivery device, alternative methods may be attempted. A drinking cup decorated with colorful stickers and O2 supply tubing inserted through the bottom of the cup is one such alternative.
COMPLICATIONS
1. Mask or cannula may be easily dislodged or removed.
2. Masks are standard size and may not fit all patients adequately and comfortably.
3. Facial irritation and skin breakdown may result if a mask is too tight.
4. Some patients may be poorly tolerant of tight fitting masks.
5. Mask must be removed for the patient to eat, drink, expectorate, or blow the nose.
PROCEDURE 26 Application and Removal of Oxygen Tank Regulators
CONTRAINDICATIONS AND CAUTIONS
1. Secure oxygen cylinders in support stand to avoid damage during transport and storage. The pressurized oxygen may turn the cylinder into a “torpedo” if damage occurs to the regulator or to the tank or valve stem (Pollack, 2005).
2. Cylinders can be heavy and cumbersome to handle. An E-cylinder weighs approximately 16 lbs. Some newer medical oxygen tanks are made of aluminum or carbon fiber. An aluminum E-cylinder weighs about 8 lbs, and a carbon fiber cylinder comparable in liter capacity to an E-cylinder weighs about 4 lbs. Do not drag, slide, or roll a cylinder. Use a portable carrier to move it to the point of use.
3. Never drop a cylinder or allow it to strike another surface.
4. To prevent fire, never permit oil, grease, or other highly flammable materials to come in contact with oxygen cylinders, valves, regulators, or fittings.
5. To prevent an accidental readjustment of oxygen flow, never drape anything over the cylinder or the regulator.
6. Use only the proper wrench or key to open or close the post valve; that is, a key that has a circular opening. Keys that have a hexagonal opening of approximately 1 inch should be discarded. Use of an incorrectly shaped key can loosen the retaining nut on the stem of the cylinder and may result in serious injury or death.
7. Oxygen tanks should be stored according to hospital policies and procedures based on The Joint Commission (TJC) guidelines.
8. In the United States oxygen is traditionally stored in green tanks. Each tank must also be labeled with its contents. Always read the label on the tank to confirm it contains the desired gas.
EQUIPMENT
Cylinder of oxygen (E-cylinder is the most commonly used size in the emergency department setting [Figure 26-1])
Regulator with flowmeter and cylinder pressure gauge (pin index safety system compatible with an oxygen cylinder [Figure 26-2])
Nut and tailpiece (“Christmas tree,” nipple) adapter
Wrench or key (some cylinder posts may have a regulator knob, and these do not require a wrench)
PROCEDURAL STEPS
Application of Regulator (Pollack, 2005)
1. Secure the cylinder in a support stand or assigned location on the stretcher or transport cart.
2. Remove the protective seal from the post valve. Inspect the opening to ensure that it is free of debris and dirt.
3. Turn the post-valve outlet away from any personnel. Warn anyone present that a loud noise is going to occur. Turn the post valve open (counterclockwise) and close it quickly with the key. This action produces a “whooshing” sound. That clears (cracks) the valve and eliminates any dust or foreign materials. If you have difficulty remembering which direction to turn the key, the saying “righty-tighty, lefty-loosey” may help.
4. Place the yoke on the cylinder, making sure the fittings are compatible and the gasket or sealing washers are in place (see Figure 26-2).
5. Tighten the yoke securely with an appropriate wrench or “T-bar” (Figure 26-3; also see Figure 26-2).
7. Slowly open the post valve until the pressure-gauge needle stops rising. Usually, one full turn is sufficient. The pressure gauge on a full E-cylinder reads about 2000 lb per square inch (psi).
8. Assess the system for any audible leaks. If a leak is heard, turn off the post valve and open the flowmeter to bleed all pressure from the regulator. Retighten the connections and open the post valve.
9. Check the pressure gauge to ascertain whether cylinder pressure is adequate for a sufficient supply of gas. Do not use the cylinder for transporting a patient if the pressure gauge reads below 500 psi. To calculate the approximate amount of oxygen left in a tank at a given flow rate, the following formula may be used (Bledsoe, Porter, & Cherry, 2006):
Table 26-1 lists the cylinder factor for the most common cylinder sizes.
10. Connect the desired form of patient oxygen delivery device (see Procedure 25).
11. Open the flowmeter to register desired flow rate. If you are using the “ball-type” flowmeter, the middle of the ball should be at the desired level (see Figure 26-3).
12. When the cylinder is not in use, turn the post valve off and bleed the system by turning the flowmeter open until the pressure gauge reads “0.”
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