Ch. 1: Oxygen and Medical Gas Therapy Flashcards
Storage and Control of Medical Gases
Gas cylinders are stored at high pressures; a full O2 cylinder contains ____ psig pressure.
2200
What is the color of this cylinder?
Oxygen
Green
White (internationally)
What is the color of this cylinder?
Helium
Brown
What is the color of this cylinder?
Carbon dioxide
Gray
What is the color of this cylinder?
Nitrous oxide
Light blue
What is the color of this cylinder?
Cyclopropane
Orange
What is the color of this cylinder?
Ethylene
Red
What is the color of this cylinder?
Air
Yellow
What is the color of this cylinder?
CO2/O2
Gray and Green
What is the color of this cylinder?
He/O2
Brown and Green
What safety system do large cylinders use?
ASSS - American Standard Safety System
What safety system do small cylinders use?
Pin Index Safety System
Indications of Oxygen Therapy: (3)
- Hypoxemia
- Labored breathing or dyspnea
- Increased myocardial work
What are some complications of oxygen therapy? (5)
- Respiratory depression
- Atelectasis
- Oxygen toxicity
- Reduced mucociliary activity
- ROP
Indication of NO
In term or near-term neonates of more than 34 wks who have evidence of PPHN
Inhaled NO may be beneficial in improving refractory hypoxemia in ARDS patients after chest trauma.
What type of patients would benifit from mixed gas therapy (He/O2)? (3)
- Obstruction from secretions
- Asthma (during episodes of bronchospasm)
- Airway obstructions (tumors, foreign bodies or tracheomalacia)
What is the lowest effective dose of nitric oxide (NO)?
5 ppm or less
What are some indications of hyperbaric oxygen therapy?
- CO poisoning
- Cyanide poisoning
- Decompression sickness (“the bends”)
- Gas gangrene
- Gas embolism
- Osteonecrosis
Cylinders are constructed of _____
steel.
Chrome molybdenum
What are the most common cylinder sizes for O2 storage?
H and E cylinder
True of False?
An O2 regulator cannot be attached to a helium cylinder.
True
What are the two types of safety relief devices?
- Frangible disk—breaks at 3000 psig
- Fusible plug—melts at 208° to 220° F (caused
by high ambient temperature or high pressure,
which increases the temperature)
What allow the escape of excess gas if the pressure in the cylinder increases?
Safety relief devices on cylinder valves
_____________ developed a color code system for cylinders to distinguish the various gases.
The Compressed Gas Association (CGA)
Explain how cylinders are visually tested.
Cylinders are visually tested by lowering a light bulb inside to look for corrosion.
How often are cylinders tested for corrosion?
Cylinders are hydrostatically tested every 5 or 10 years, depending on the cylinder marking.
What does a star next to latest test date mean?
A star next to the latest test date means the next test must be done 10 years from that date.
What does hydrostatic testing determine?
The amount or number of:
(1) Wall stress
(2) Cylinder expansion
(3) Leaks
What type of O2 is most commonly produced by the process of fractional distillation?
Liquid O2
Liquid O2 is stored in Thermos containers at a pressure not to exceed ______ and what temperature?
250 psig and at a temperature below -297° F (the boiling point of O2).
Regulators are devices attached to the cylinder valve to __________.
regulate flow and reduce cylinder pressure to working pressure (i.e., 50 psig).
Dust or debris entering the regulator from the cylinder valve may rupture the diaphragm.
How do you prevent this?
Always “crack” the cylinder before attaching a regulator. This is accomplished by turning the cylinder on and back off quickly to blow out the debris from the cylinder outlet.
Constant pressure trapped in the pressure chamber after the cylinder is turned off may rupture the diaphragm.
How do you prevent this?
Always vent pressure in the regulator by turning the flowmeter back on after the cylinder is turned off.
What are the cylinder factors for H and E?
H cylinder = 3.14 L psig
E cylinder = 0.28 L psig
Duration of flow EQUATION
Cylinder pressure x cylinder factor / flow rate
What are the three ways to determine whether a flowmeter is compensated for pressure?
(a) It is labeled as such on the flowmeter.
(b) The needle valve is located after the float.
(c) The float jumps when the flowmeter, while it is turned off, is plugged into a wall outlet.
Flowmeter outlets use which safety system?
the Diameter Index Safety System, as do all gas-administering equipment that operates at less than 200 psig, so that attachment to the wrong gas source is avoided.
Uncompensated or compensated flowmeter?
The needle valve is located proximal to (before) the float; therefore atmospheric pressure is in the Thorpe tube. Any back pressure in the tube affects the rise of the float.
Uncompensated flowmeter
Uncompensated flowmeters should not be used clinically
Uncompensated or compensated flowmeter?
The needle valve is located distal to (after) the float; therefore 50 psig is in the tube. Only back pressure that exceeds 50 psig will affect the rise of the float.
Compensated or compensated flowmeter
The flowmeter reads accurately with an attachment, such as a humidifier or nebulizer on the outlet, or with any obstruction downstream. If the O2 tubing is completely obstructed with no gas flowing to the patient, the flowmeter will reflect that with a flow reading of near 0.
Technical problems associated with reducing valves and regulators
A weak spring can result in diaphragm vibration and inadequate flows that are caused by ____________________.
premature closing of the inlet valve.
Does this describe a compensated or uncompensated flowmeter?
When a restriction, such as a humidifier or a nebulizer, is attached to the outlet, back pressure into the tube forces the float down and compresses the gas molecules closer together so that more molecules go around the float than are indicated by the float. Therefore the flowmeter reading is lower than the amount the patient is actually receiving.
Uncompensated flowmeter
What should be done in this instance?
If the flowmeter is turned off completely but gas is still bubbling through the humidifier or is heard coming from the flowmeter.
The valve seat is faulty and the flowmeter should be replaced.
The Bourdon gauge flowmeter is a pressure gauge that has been calibrated in liters per minute. It is compensated or uncompensated for back pressure?
Uncompensated for back pressure
When a humidifier or nebulizer is attached to the outlet of the Bourdon gauge, back pressure is generated into the gauge (which measures pressure), and the gauge reading is higher or lower than the amount the patient is actually receiving?
HIGHER
What is the advantage of the Bourdon gauge over the Thorpe tube?
The advantage of the Bourdon gauge is that it is not position dependent. It reads just as accurately in a horizontal position as it does in a vertical position. This makes it the flowmeter of choice when transporting a patient with an oxygen tank.
Signs and Symptoms of Hypoxemia
- Tachycardia
- Dyspnea
- Cyanosis (unless anemia is present)
- Impairment of special senses
- Headache
- Mental disturbance
- Slight hyperventilation
COMPLICATIONS OF OXYGEN THERAPY
How would you prevent respiratory depression?
Patients with COPD who is chronically hypoxic is most affected. Maintain PaO2 between 50 and 65 mm Hg for these patients.
COMPLICATIONS OF OXYGEN THERAPY
How do we prevent atelectasis?
High O2 concentrations in the lung can wash out nitrogen in the lung and reduce the production of surfactant, which may lead to atelectasis. Maintain FiO2 below 0.60.
COMPLICATIONS OF OXYGEN THERAPY
How do we prevent oxygen toxicity?
High O2 concentrations result in increased O2 free radicals and therefore lung tissue toxicity. This may lead to acute respiratory distress syndrome (ARDS). Maintain FiO2 below 0.60.
COMPLICATIONS OF OXYGEN THERAPY
How do we prevent reduced mucililary activity?
Maintain FiO2 below 0.60. The beating of the cilia in the mucociliary blanket is not as active when high FiO2 levels are used.
COMPLICATIONS OF OXYGEN THERAPY
How do we prevent retinopathy of prematurity (ROP)?
This is caused by high PaO2 levels in infants and results in blindness. It is more common in premature infants. Maintain PaO2 below 80 mm Hg. The normal level of PaO2 in infants is 50 to 70 mm Hg.
NORMAL PaO2 VALUES BY AGE
Less than or equal to 60 years old
80 mm Hg