During a suctioning procedure a patient experiences tachycardia with PVCs. What is likely responsible for this response?
Inadequate preoxygenation
A patient with a history of carbon dioxide retention is receiving oxygen at 6 L/min via nasal cannula. He is becoming lethargic and difficult to arouse. In regard to the oxygen delivery, what change would you recommend?
Reduce the flow to 2 L/min and obtain an ABG
A patient is receiving oxygen therapy from a Nonrebreathing mask with a flow of 10 L/min. The respiratory therapist observes the bag deflating with each inspiration. What action is indicated in this situation?
Increase the flow to the mask
A patient is to receive a mixture of helium and oxygen. Which delivery device would be appropriate and why?
Nonrebreathing mask, and because of the tight fit with little or no air entrainment.
An 80/20 mixture of helium and oxygen is administered. The oxygen flowmeter is set at 10 L/min. What is the actual flow delivered to the patient?
18 L
A patient is receiving 40% oxygen via an air entrainment mask with a flowmeter set at 8 L/min. What is the total flow delivered to the patient?
32 L/min
Water has accumulated in the delivery tubing of an aerosol system. This will not result in what?
Increased total flow
A patient requires a flow rate of 40 L/min to meet his inspiratory demand for gas. He is to receive oxygen via a venturi mask set at 24%. What is the minimum flow setting on the flowmeter to produce the appropriate flow?
2 L/min
You should add a humidifier to a nasal cannula when what?
When the flow exceeds 4 L/min
What is acute hypoxemia?
Sudden decrease level of oxygen in blood
What are the threshold criteria for defining hypoxemia in adults ? PaO2 and SaO2
PaO2 is less than 60 mmHg
SaO2 is less than 90%
What beneficial effect does oxygen have on symptoms of patients with COPD and chronic hypoxemia
COPD- less dyspnea on oxygen
Chronic Hypoxemia- Improve mental function and decrease pulmonary vascular resistance
In what acute cardiac condition is oxygen therapy especially important
Myocardial infarction
State the 3 ways to determine if a patient needs oxygen therapy
1. Use lab measures to document hypoxemia
2. Patients clinical problem or condition
3. Distressed overall appearance or bedside assessment
State 3 specific clinical objectives of oxygen therapy
1. Correct acute hypoxemia
2. Decrease symptoms of chornic hypoxemia
3. Decrease cardiopulmonary workload
Oxygen toxicity affects what two organ systems and what is the affect?
Respiratory- Bronchopneumonia and tracheobronchitis
Central nervous system: tremors, twitches, and seizures
Describe the pathophysiology of how excessive blood oxygen causes blindness in premature newborns
An excessive blood O2 level causes retinal vasoconstriction, which leads to necrosis of the blood vessels. Termed, retinopathy of prematurity
Describe how oxygen can cause absorption atelectasis?
Quick breathing depletes body Nitrogen.
What patients are at increased risk for absorption atelectasis and how do you reduce the risk?
Patients at low tidal volumes and you have them take a deep breath.
Oxygen device that always exceeds patient's inspiratory needs
High flow system
Oxygen device that provides some of the patient's inspiratory needs
Low flow system
Oxygen device that may meet needs if no leaks occur
Reservoir system
Oxygen therapy goal
-maintain adequate tissue oxygenation
-minimizing cardiopulmonary work
Clinical objectives for oxygen therapy
-correct documented or suspected acute hypoxemia
-decrease symptoms associated with chronic hypoxemia
-decrease workload hypoxemia imposes on the cardiopulmonary system
Documented hypoxemia as evidenced by
-PaO2 less that 60mmHg
-SaO2 less than 90%
-PaO2, SaO2 below desirable range for a specific situation
Indications for oxygen therapy
-acute care situations with hypoxemia
-severe trauma
-acute myocardial infarction
-short term therapy or surgical intervention
Contraindications for oxygen therapy
Certain delivery devices are contraindicated: nasal cannulas, nasopharyngeal catheters in peds/neo patients with nasal obstruction
PaO2 greater than or equal to 60 mmHg:
Ventilator depression may occur rarely in spontaneously breathing patients with elevated PaCO2
With FiO2 greater than 0.5:
Absorption atelectasis, O2 toxicity or depression of ciliary or leukocyte function may occur
In premature infants, PaO2 greater than 80 mmHg may contribute to:
Retinopathy of prematurity
In infants with certain congenital heart lesions such as hypoplastic left heart syndrome...
High PaO2 can compromise the balance between pulmonary and systemic blood flow
In infants, O2 flow directed at the face may stimulate:
an alteration in respiratory pattern
Increased FiO2 can worsen lung injury in patients with:
paraquat poisoning or patients receiving bleomycin
During laser bronchoscopy or tracheostomy:
minimal FiO2 should be used to avoid intratracheal ignition
Fire hazard increased in:
the presence of high FiO2
Three basic designs of O2 delivery systems:
low flow
high flow
reservoir
Low-flow system: nasal cannula
-delivers FiO2 of 0.24 to 0.40
-used with flow rates of 1/4 to 8 L/min
-FiO2 depends on how much room air patient inhales in addition to O2
-device is usually well tolerated
-a humidifier is used when the input flow is greater than 4 L/min
Low flow system: nasal catheter
-generally limited to short term O2 administration during specialized procedures (a bronchoscopy)
-used at flows 1/4 to 8 L/min
-delivers FiO2 of 0.22-0.45
-should be replaced with a new one at least every 8 hours (opposite naris)
-has been replaced by na
Oxygen therapy: transtracheal catheter
-surgically placed in trachea through neck by physician
-uses 40% to 60% less O2 to achieve same PaO2 by nasal cannula
-used with flow rates of 1/4 to 4 L/min
-complications: infection
Low flow systems provide O2 concentrations of:
Ranging from 22% at 1 L/min to 60% at 15 L/min
The range of 8 L/min in a low flow system is based on
Upper limit of comfortable flow
Concentration delivered by low flow system varies with:
amount of air dilution
Performance characteristics of low-flow systems (increases FiO2)
-higher O2 input
-mouth closed breathing (cannula only)
-low inspiratory flow
-low tidal volume
-slow rate of breathing
-small minute ventilation
-long inspiratory time
-high I:E ratio
Performance characteristics of low-flow systems (decreases FiO2)
-lower O2 input
-mouth closed breathing (cannula only)
-high inspiratory flow
-high tidal volume
-fast rate of breathing
-large minute ventilation
-short inspiratory time
-low I:E ratio
Troubleshooting low-flow systems
...
Reservoir systems: cannulas
-designed to conserve oxygen (nasal, and pendant reservoir)
-can reduce oxygen as much as 50%-75%
-humidification not usually needed
Three types of reservoir systems: masks
simple mask
partial rebreathing mask
non breathing mask
Reservoir: simple mask flow range
5-10 L/min
When simple mask is less than 5 L/min
the mask volume acts as dead space and causes carbon dioxide (CO2) rebreathing
Simple mask FiO2 range
0.35-0.5
Simple mask
� Air dilution easily occurs during inspiration through its ports and
around its body, provides a variable FiO2
� FiO2 varies depending on the O2 input flow, the mask volume, the extent of air leakage, and the pa<ent's breathing pattern
Reservoir: partial rebreathing mask flow
Minimum of 10 L/min to prevent collapse of bag
Partial rebreathing mask bag
Increases reservoir volume, provides higher FiO2 capabilities
Parts of partial rebreathing mask
-no valves
-O2 flows into mask and passes directly to patient
-Source O2 enters the bag
Reservoir: non rebreathing mask flow and FiO2 range
minimum 10 L/min
0.6-0.8
Nonrebreathing mask
-more common than partial rebreathing mask
-prevents rebreathing with one way valves
During inspiration of non rebreathing mask
-slight negative mask pressure closes the expiratory valves preventing air dilution
-inspiratory valve on top of bag opens, providing O2 to the patient
During exhalation in non rebreathing mask
valve action reverses the direction of flow
Inhalation and exhalation ports non rebreathing mask
-an inspiratory valve at the top of bag
-expiratory valves cover the exhalation ports on the mask body
Common problems with reservoir masks include:
� Device displacement
� System leaks and obstructions
� Improper flow adjustment
� Skin irritation
Peak inspiratory flow, high-flow systems
At least 60 L/min total flow
The average adult peak inspiratory flow during tidal ventilation is:
approximately three times the minute volume
High flow systems can:
ensure fixed FiO2
High flow systems most suitable for patients requiring:
precise FiO2 with high or variable minute ventilation
-air entrainment
-blending systems
High pressure O2 source through:
small nozzle or jet surrounded by air entrainment ports
The amount of air entrained at ports varies directly with:
the size of the port and the velocity of O2 at the jet
FiO2 provided by air entrainment devices depends on:
air-to-O2 ratio
Problems with downstream flow resistance
-increased downstream flow resistance causes back pressure
-back pressure decreases both volume of entrained air and the total flow output of devices
With less air entrained, the delivered O2 concentration increases because:
total flow output also decreases; effect on FiO2 varies
High flow nasal cannula three main features
1. Delivers a high FiO2
2. Meets or exceeds the patient's minute ventilation and therefore
acts as a fixed oxygen delivery device
3. Generates a distending positive airway pressure
High flow nasal cannula examples
� Vapotherm Precision flow System
� Fisher and Paykel's Optiflow
Blending systems are considered when:
air entrainment devices cannot provide a high enough O2 concentration or flow
Blending systems separate:
Pressurized air and O2 sources
Oxygen blenders
air and O2 enter the blender and pass through dual pressure regulators that exactly match the two pressures
Enclosures
� Oxygen hood (AKA: Oxyhood): Generally is best method for delivering controlled oxygen to infants
� Incubators (AKA Isolette): Can be used in conjunction with oxyhood
� Oxygen tent: Regulating cooling and FiO2 can be difficult
Three P's
purpose
patient
performance
Patient considerations
hypoxemia severity
age group
degree of consciousness
tracheal airway
stability of minute ventilation
mouth breathing
Performance
-O2 systems vary according to actual FiO2 delivered and stability of FiO2 under changing patient demands
Hyperbaric oxygen (HBO) therapy
The therapeutic use of O2 at pressures greater than 1 atm
Physiologic effects
� Bubble reduction (Boyle's law)
� Hyperoxygenation of blood and tissue (Henry's law)
� Vasoconstriction
� Enhanced host immune function
� Neovascularization
Hyperbaric oxygen therapy: methods of administration (mono)
Can hold only one patient
A multiple place chamber large tank (12+ people)
-air locks
-filled with air
-only the patients breathes supplemented O2 through a mask
Hyperbaric indications (acute)
...
Hyperbaric indications (chronic conditions)
� Diabetic wounds of the lower extremities and other non-healing wounds
� Refractory osteomyelitis
� Actinomycosis (chronic systemic abscesses)
� Radiation necrosis (HBO as an adjunct to conventional treatment)
Criteria for HBO in CO poisoning
-history of unconsciousness
-presence of neuropsychiatric abnormality
-presence of instability or cardiac ischemia
-carboxyhemoglobin level 25%
Complications and hazards of HBO (barotrauma)
-ear or sinus trauma
-tympanic membrane rupture
-alveolar over distention and pneumothorax
-gas embolism
Complications and hazards of HBO (oxygen toxicity)
-CNS toxic reaction
-pulmonary toxic reaction
Complications and hazards of HBO (other)
-fire
-sudden decompression
-reversible visual changes
-claustrophobia
-decreased cardiac output
Nitric oxide therapy
-improves blood flow to lungs
-reduces shunting
-improves oxygenation
-decreases pulmonary vascular resistance
-lower cost
Nitric oxide therapy potential uses for inhaled nitric oxide
-ARDS
-persistent pulmonary hypertension of the newborn
-primary pulmonary hypertension
-pulmonary hypertension after cardiac surgery
-cardiac transplantation
-acute pulmonary embolism
-COPD
-congenital diaphragmatic hernia
-sickle cell disease
-testing p
Adverse effects associated with nitric oxide therapy
-poor paradoxical response
-methemoglobinemia
-increased left ventricular filling pressure
-complications of certain cardiac anomalies
-rebound hypoxemia, pulmonary hypertension
Features of ideal nitric oxide delivery system
-dependability and safety
-delivery of precise and stable dose of NO
-limited production of nitrogen dioxide
-accurate monitoring of levels
-maintenance of adequate patient ventilation
Helium oxygen therapy
-value of helium as therapeutic gas is based solely on its low density
-can decrease work of breathing for patients with airway obstruction
Guidelines for use of helium oxygen therapy
-helium must always be mixed with oxygen
-heliox can be prepared bedside or pre mixed cylinders
-heliox should be delivered to patients via tight fitting non rebreathing mask with high flow
O2 flowmeter is inaccurate because of the lower density of helium
-the correction for an 80:20 helium mixture is 1.8 for every 10 L/min indicated flow
Troubleshooting helium oxygen therapy
-poor vehicle or aerosol transport
-reduces effectiveness of coughing
-badly distorts patients voice
-hypoxemia
CO2 O2 therapy
-hiccoughs
-CO poisoning
-preventing wash out of CO2
-5:95 or 7:93