Chapter 42- Medical Gas Therapy Flashcards
How do RT’s know what to do?
Guidelines that are established by the American Association of Respiratory Care to help guide practitioners in delivering safe and effective patient care
What is the overall goal of O2 therapy?
- Maintain adequate tissue oxygenation
- Minimizing cardiopulmonary work
What is the clinical objectives for O2 therapy?
- Correct documented or suspected acute hypoxemia
- Decrease symptoms associated with chronic hypoxemia
- Decrease the workload hypoxemia imposes on the cardiopulmonary system
What are some indications for needing oxygen therapy?
- Documented hypoxemia as evidenced by: –PaO2 less than 60 mm Hg/SpO2 less than 90% on R/A
- Acute care situations in which hypoxemia is suspected
- Severe trauma
- Acute myocardial infarction
- Short term therapy or surgical intervention
- Tachycardia, tachypnea, confusion
What are some precautions and/or possible complications with oxygen therapy with a PaO2 greater than or equal to 60 mm HG?
Ventilator depression may occur rarely in spontaneously breathing patients with elevated PaCO2
What are some precautions and/or possible complications with oxygen therapy when a patient has a FiO2 greater than 0.5?
Absorption atelectasis, O2 toxicity, or depression of ciliary or leukocyte function may occur
What are some precautions and/or possible complications with oxygen therapy in premature infants?
PaO2 greater than 80 mm Hg may contribute to retinopathy of prematurity
What are some precautions and/or possible complications with oxygen therapy in infants with heart problems?
Infants with certain congenital heart lesions such as hypoplastic left heart syndrome, High PaO2 can compromise the balance between pulmonary and systemic blood flow
What are some precautions and/or possible complications with oxygen therapy in general to infants?
In infants, O2 flow directed at the face may stimulate an alteration in respiratory patter.
What are some precautions and/or possible complications with oxygen therapy in infants with current lung injury?
Increased FiO2 can worsen lung injury in patients with paraquat positioning or patients receiving bleomycin
What is paraquat?
Insecticide, used for commercial use only
What is bleomycin?
Drug to treat cancer patients
What are some precautions and/or possible complications with oxygen therapy for asthma patients?
During laser bronchoscopy or tracheostomy, minimal FiO2 should be used to intratracheal ignition
What are some precautions and/or possible complications with oxygen therapy and fire?
Fire hazard increased in the presence of high FiO2
What are some precautions and/or possible complications with oxygen therapy with typical ventilation?
Depression of ventilation on FiO2. This is not typical.
What is ABG’s?
Arterial blood gas-the cornerstone of dx of management of oxygenation and acid-base disturbances?
What is the WNL of pH during an ABG?
acid/base (H+) balance of blood (7.35-7.45)
What is the WNL of PaO2 in a ABG?
Partial pressure of oxygen dissolved in the arterial blood. Normal limits are (80-100 mm Hg)
What is the WNL of PCO2 in a ABG?
Partial pressure of carbon dioxide dissolved in arterial blood (35-45 mm Hg)
What is the WNL of HCO3 in a ABG?
The calculated value of the bicarbonate in blood (22-26 mEq/liter)
What are the 3 basic designs for O2 delivery?
Low-flow, high-flow and reservoir system?
Low-Flow systems: Nasal Cannula
What is the FiO2 range?
Delivers FiO2 of 0.24 to 0.40 %
Low-Flow systems: Nasal Cannula
Why is the flow rate?
Used with flow rates of 1/4 to 8 L/min
Low-Flow systems: Nasal Cannula
Does the flow depend?
Yes, its depends on how much room air a patient inhales in addition to O2
Low-Flow systems: Nasal Cannula
When do you use a humidifier?
A humidifier is used when the input flow is greater than 4 L/min
Low-Flow systems: Nasal catheter
When is this used?
Generally limited to short-term O2 administration during specialized procedures
Example: Bronchoscopy
Low-Flow systems: Nasal catheter
What is the flow rate?
Used at flows of 1/4 to 8 L/min
Low-Flow systems: Nasal catheter
What FiO2 is given to the patient?
Delivers FiO2 of 0.22 to 0.45 %
Low-Flow systems: Nasal catheter
When should they be replaced?
At least every 8 hours and placed in the opposite naris
Transtracheal Catheter
What is it?
Catheter surgically placed in the trachea through the neck by a physican
Transtracheal Catheter
flow rate?
Used with flow rates of 1/4 to 4 L/min
Transtracheal Catheter
What are some disadvantages?
Requires careful maintenance and clean. Also complications such as infection are possible
Name some characteristics of low-flow systems?
- Provide O2 concentrations ranging from 22%at 1 L/min to 60% at 15 L/min
- Concentration delivered by a low-flow system varies with the amount of air dilation
How much FiO2 changes per liter?
Each 1 L/min nasal O2 increases FiO2 approximately 4%
List the FiO2 at different liter flows for nasal cannulas
1 lpm is 24% 2 lpm is 28% 3 lpm is 32% 4 lpm is 36% 5 lpm is 40% 6 lpm is 44%
How do we increase FiO2 while using a low-flow device?
Higher O2 output Mouth-closed breathing Low inspiratory flow Slow rate of breathing Low tidal volume
How do we decrease the FiO2 while using a low-flow device?
Lower O2 input Mouth-opening breathing High inspiratory flow Fast rate of breathing High tidal volume
How do we troubleshoot low-flow system?
Inaccurate flow
System leaks and obstructions
Skin irritation
Device displacement
What are some solutions to trouble shooting low-flow device?
Check connections
Adjust flowmeter
Check connections
Fill for gas and adjust as needed
Reservoir system: cannulas
What are they designed to do?
Designed to conserve oxygen for both nasal reservoir and pendant reservoir
-Can reduce O2 use by 50-70%
Reservoir system: Mask
What are the 3 types of the masks?
- Simple mask
- Partial rebreathing mask
- Nonrebreathing mask
Simple Mask
What is the input flow range?
Adult simple mask is 5 to 10 L/min
-At a flow of less than 5 L/min, the mask volume acts as dead space and causes CO2 rebreathing
Simple Mask
What would happen at a flow less than 5 L/min?
At a flow less than 5 L/min, the mask volume acts as dead space and causes carbon dioxide (CO2) rebreathing
Simple Mask
What is the FIO2 range?
Range is 0.35 to 0.50
-Air dilution easily occurs during inspiration through it’s ports and around its body, provides a variable FiO2
Simple Mask
Does the FiO2 vary?
YES, FiO2 varies depending on the O2 input flow, the mask volume, the extent of air leakage and the patients breathing pattern
Partial Rebreathing Mask
Does this have higher FiO2 than a simple mask?
Yes, because the bag increases the reservoir volume, provides high FiO2 capabilities than a simple mask
Partial Rebreathing Mask
3 key points of this mask?
- A partial rebreathing source O2 flows into the mask and passes directly to the patient
- A partial rebreathing mask has no valves
- During exhalation, source O2 enters the bag
Partial Rebreathing Mask
What is the input flow range for an adult?
Minimum of 10 L/min to prevent bag collapse on inspiration
Partial Rebreathing Mask
What is the FiO2 range?
0.40 t0 0.80
Nonrebreathing mask
Describe it
Prevents rebreathing with one-way valves. An inspiratory valve sits on top of the bag, and expiratory valve covers the exhalations ports on the mask body preventing air dilution
Nonrebreathing mask
What happens with the valve on top of the mask?
At the same time of the of the calve on the side of the mask, the inspiratory valve on the top of the bag opens, providing O2 to the patient
Nonrebreathing mask
What happens during exhalation?
During exhalation, valve action reverse the direction of flow
List some troubleshooting of reservoir system?
- device displacement
- system leaks and obstructions
- improper flow adjustment
- skin irritation
What is a high flow system?
A system that gives O2 concentration at flow equaling or exceeding patients peak inspiratory flow
What is considered a high flow system?
- Air-entrainment system
- Blending system
What patient would use a high-flow system?
Patients who are requiring precise FiO2, with high or variable minute ventilation
What amount of air entrained in the ports connect with?
The amount of air entrained at port varies directly with the size of the port and the velocity of O2 at the jet
What would cause the FiO2 in a air-entrainment system varies?
- The air-to-O2 ration
- The amount of flow resistance downstream from the mixing site
Describe the Air-Entrainment Mask (Venturi)
Air is entrained by shear forces at the boundary of jet flow, not by low lateral pressures
-The smaller the orifice the greater the velocity of O2, and more air entrained
Describe Air-Entrainment neubilzer
Power air-entrainment nebulizers have most of the features of AEMs but have added capabilities including additional humification and temperature control
What would cause an issue with air-entrainment system?
Any increase in flow resistance downstream from (distal to) the point of air entrainment alters the performance of all-air entrainment system
What are 3 main features of a high-flow nasal cannula?
- delivers a high FiO2
- meets or exceeds the patients minute ventilation and therefore acts as a fixed oxygen delivery device
- generates a distending positive airway pressure
What are the names of high-flow nasal cannulas?
- Vapotherm precision flow system
- Fisher and Paykel Optiflow
What the features of oxygen blender system?
Air and O2 enter the blender and pass through dual pressure regulators that exactly match the two pressures
What are two other oxygen delivery devices?
- Bag-mask devices
- demand flow and pulse dose system
How do you select a delivery approach?
The three P’s - purpose, patient and performance
Selecting a delivery approach:
Purpose?
The general purpose of all O2 therapy is to increase FiO2 sufficiently to correct arterial hypoxemia
Selecting a delivery approach:
Patient
Patient considerations
-Severity and cause of hypoxemia, patient age group, degree of consciousness and alertness.
Selecting a delivery approach:
Performance
O2 systems vary according to actual FiO2 delivered and stability of FiO2 under changing patient demands
What is an O2 therapy protocol?
An order for “O2 therapy via protocol” permits O2 therapy to be initiated, modified or discontinued by the RT
What does a well designed O2 protocol ensures to the patient?
- Undergoes initial assessment
- Evaluated for protocol criteria
- Receives a tx plan that is modified to the need
- Stops receiving therapy as soon as it is no longer needed
What is hyperbaric oxygen (HBO) therapy?
The therapeutic use of O2 at pressures greater than 1 atm
1 atm- 760 mmHG
Allows us to hyperoxygenation the blood and tissues
When would you used hyperbaric oxygen therapy?
Chronic conditions:
- diabetic wounds of the lower extremities and other nonhealing wounds
- refractory osteomyelitis
- chronic system abscesses
What is some criteria for HBO in CO poisoning?
- History of unconsciousness
- -presence of neuropsychiatric abnormality
- presence of cardiac instability
Complications and Hazards of HBO?
Barotrauma: -Ear or sinus trauma -gas embolism -alveolar overdistention and pneumothorax O2 toxicity: -CNS toxic reaction -pulmonary toxic reaction Other: -fire -sudden decompression -claustrophobia
Nitric oxide therapy: advantages
- improves blood flow to lungs
- reduces shunting
- improves oxygenation
- decreases pulmonary vascular resistance
- lower cost alternative to drug therapies
What are some potential uses for inhaled nitric oxide?
- ARDS
- Persistent pulmonary hypertension of the newborn
- COPD
- Acute pulmonary embolism
What are some concerns of nitric oxide therapy?
- poor or paradoxical response
- increased left ventricular filling pressure
- complications of certain cardiac anomalies
Helium-oxygen therapy:
What does it do and who would use it?
- Value of helium as therapeutic gas is based solely on its low density.
- Can decrease work of breathing for patients with airway obstruction
What are some guidelines for helium-oxygen therapy?
- Helium must always be mixed with O2
- Heliox can be prepared at bedside or used from premixed cylinders
- In general, heliox should be delivered to patients via tight fitting nonrebreathing mask with high flow
What is some troubleshooting and hazards of helium-oxygen therapy?
- poor vehicle for aerosol transport
- reduces effectiveness of coughing
- badly distorts patients voice
