Modalities of oxygen therapy in PICU 31 3-14
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Transcript of Modalities of oxygen therapy in PICU 31 3-14
Modalities of oxygen therapy in PICU
Dr Suresh Kumar. MBBS, MD, FIAP (PCC), DNB, PGDS, DM (fellow, PCC)
31-3-14
Overview
Need of oxygen therapy
Oxygen delivery system
Oxygen delivery devices
Individual oxygen delivery devices and techniques
Humidification
Complication of oxygen therapy
Practical considerations
Joseph Priestley (1775)
Heated mercuric oxide and obtained air that caused candles to burn more brightly
Dephlogisticated air (Oxygen)
“From the greater strength and vivacity of the flame of a candle, in the pure air, it may be conjectured, that it might be particularly
salutary to the lungs in certain morbid cases when the common air would not be sufficient though the pure air (oxygen) might be very
useful as a medicine”
Scott Haldane (1860–1936) was first to brought oxygen therapy to a rational and scientific basis
Ubiquitous in modern medicine
Oxygen administration and airway management are two of the fundamental aspects of management in a patient with acute respiratory failure
Proper application of oxygen therapy and airway management are life saving
In the absence of O2 (hypoxia), cellular respiration ceases and irreversible cellular injury and death occur within minutes
Despite the importance of these therapies and their frequent use in the acute care setting, their nuances are often under-appreciated
Oxygen
Colourless, odourless
Medical grade O2 is manufactured by fractional distillation of liquefied air
It is stored as a liquid to reduce the size of the storage container
1 L of liquid O2 produces 860 L of gaseous O2
Most important indication for O2 therapy is to treat hypoxemia
The alveolar gas equation illustrates how increasing the inspired O2 fraction (FIO2) increases the alveolar PO2 (PAO2) and subsequently the arterial PO2 (PaO2)
PAO2 = FIO2(PB-47)-1:25PaCO2
Increasing FIO2, lead to increase in PAO2 In cases of shunt (V/Q=0), supplemental O2 therapy has little
effect on PaO2 If the cause of hypoxemia is low V/Q or diffusion defect,
supplemental O2 therapy will effectively increase the PaO2
PAO2 = 0.21 X 713 - 40/0.8 = 100PAO2 = 0.50 X 713 - 40/0.8 = 306PAO2 = 0.80 X 713 - 40/0.8 = 520
Oxygen therapy
Administration of oxygen at concentration higher than in environment (>21%)
Purpose: Increase oxygen saturation in blood and tissues when it is low due to disease or injury
For oxygen to increase PaO2, there has to be units of low ventilation with normal or near normal perfusion
Any true extra or intrapulmonary R-L shunting will be largely unaffected by increase in alveolar oxygen tension (PAO2)
Oxygen administration by simple tubes and masks to advanced support systems like ECMO
Oxygen therapy in non-intubated children
Goal of oxygen delivery
Maintain targeted SpO2 levels through the provision of supplemental oxygen in a safe and effective way
Relieve hypoxemia and maintain adequate oxygenation of tissues and vital organs
Give oxygen therapy in a way which prevents excessive CO2 accumulation
Reduce the work of breathing
Efficient and economical use of oxygen
Ensure adequate clearance of secretions and limit the adverse events of hypothermia and insensible water loss
Oxygen delivery system
Oxygen source
Pressure regulator and flow meter
Oxygen delivery device
Patient
PatientIndications for oxygen delivery
Documented hypoxia/hypoxemia
Achieving targeted percentage of oxygen saturation
The treatment of an acute or emergency situation where hypoxemia or hypoxia is suspected, and if the child is in respiratory distress manifested by: Dyspnea, tachypnea, bradypnea, apnea
pallor, cyanosis
lethargy or restlessness
use of accessory muscles: nasal flaring, intercostal or sternal recession, tracheal tug
Circulatory compromise
Pulmonary hypertension
Short term therapy: post anesthetic or surgical procedure
Palliative care: for comfort
Oxygen sources
Medical oxygen can be provided from a
Wall source Provide 50 psi (pounds per square inch ) of pressure
Cylinder Operate at 1800-2400 psi
Too much
Cannot be directly delivered to patient or run the ventilator
Need down regulating valve
Flow meter to manipulate the flow rate
Pressure regulator with flow meter
The pressure regulator controls the pressure coming out of the cylinder and is indicated on the gauge in psi
The flow meter controls how rapidly the oxygen flows from the cylinder/wall source to the victim
The flow rate can be set from 1-25 L/min
Oxygen delivery devices
Devices used to administer, regulate, and supplement oxygen to a subject to increase the arterial oxygenation
These system entrains oxygen and/or air to prepare a fixed concentration required for administration
Tubing carries the oxygen from the regulator/flow meter to the delivery device
Oxygen delivery devices…
Classified as:Low-flow or variable-performance devices:Provide oxygen at flow rates that are lower than patients’ inspiratory demandsWhen the total ventilation exceeds the capacity of the oxygen reservoir, room air is entrainedFiO2 delivered depends on the ventilatory demands of the patient, the size of the oxygen reservoir, and the rate at which the reservoir is filledAt a constant flow, the larger the tidal volume, the lower the FiO2 and vice versaFiO2 24-90%
High-flow or fixed-performance devices:Provide a constant FiO2 by delivering the gas at flow rates that exceed the patient’s peak inspiratory flow rate and by using devices that entrain a fixed proportion of room airReliable
Oxygen delivery devices…
Confusion: flow systems with oxygen concentrations
However, both are mutually exclusive in that a high-flow system, viz. Venturi mask, can deliver FiO2 as low as 0.24, whereas a low-flow system like a non rebreathing mask can deliver FiO2 as high as 0.8
If the ventilatory demand of the patient is met completely by the system: high-flow system
if the system fails to meet the ventilatory demand of the patient: low-flow system
Oxygen delivery devices…
A low-flow oxygen delivery system requires that the patient inspire some room air to meet inspiratory demands
Popular: simplicity, patient comfort, and economics
FIO2 is determined by the size of the oxygen reservoir, the oxygen flow rate, and the breathing pattern For example, a nasal cannula at an oxygen flow rate >6 L/min
accomplishes minor increases in FIO2 because the nasopharyngeal reservoir is filled with 100% oxygen at a 6 L/min flow rate
An oxygen reservoir must be increased (placing a mask over the nose and mouth) to achieve an FIO2 greater than 40%
With abnormal ventilatory patterns, the larger the tidal volume, or the faster the respiratory rate, the lower the FIO2
Oxygen delivery devices…
Low flow systems:
Nasal cannula
Intranasal catheter
Simple mask
Partial rebreathing masks
Non rebreathing mask
High flow systems:
Venturi system
Oxyhood
Face tent
Oxygen tent
High flow nasal prongs
CPAP HelioxHyperbaric oxygen
Oxygen delivery devices…
The choice of delivery device:
Patient’s oxygen requirement
Efficacy of the device
Reliability
Ease of therapeutic application
Humidification needs
Age
Patient acceptance and tolerance
Normal flow requirement
3-4 time the minute ventilation (MV = TV X RR)
eg 5 kgs child breathing at rates of 60/min
Flow rates needed: 3-4 X (60 X 6 X 5) = 5400-7200 ml/min
Nasal cannula/prongs
Two soft prongs in nostrils attached to the oxygen source Held in place over the patient’s ears Flow is directed to the nasopharynx: humidification and
heat exchange To ensure the patient is able to entrain room air around the
nasal prongs and a complete seal is not created the prong size should be approximately half the diameter of the nares
Available in different sizes Infant Pediatric Adult
Select the appropriate size for the patient's age and size
Nasal cannula/prongs…
Delivers 24-44% FiO2 at flow rate of 1-6 L/min
The slower the inspiratory flow the higher the FiO2
A maximum flow of:
2 LPM in infants/children under 2 years of age
4 LPM for children over 2 years of age
With the above flow rates humidification is not usually required
If flow >6 L/min, variable FiO2, need humidification
1 = 24%2 = 28%3 = 32%4 = 36%5 = 40%6 = 44%
Nasal cannula/prongs…
Indications Low to moderate oxygen requirement
No or mild respiratory distress
Long term oxygen therapy
Contraindications Poor efforts, apnea, severe hypoxia
Mouth breathing
Advantages
Less expensive (Rs 70/-) Comfortable, well tolerated
Able to talk and eat
Disadvantages Doesnot deliver high FiO2
Irritation and nasal obstruction
Less FiO2 in nasal obstruction
FiO2 varies with breathing efforts
Nasal cannula/prongs…
Practical considerations: Position the nasal prongs along the patient's cheek and
secure the nasal prongs on the patient's face with adhesive tape
Position the tubing over the ears and secure behind the patient's head
Ensure straps and tubing are away from the patient's neck to prevent risk of airway obstruction
Check nasal prong and tubing for patency, kinks or twists at any point in the tubing and clear or change prongs if necessary
Check nares for patency - clear with suction as required Change the adhesive tape frequently as required Check frequently that both prongs are in nostrils
Intranasal catheters
Flexible catheter with holes at distal 2 cms
FiO2 35-40%
Measured from nose to ear, lubricated and inserted to just above the uvula
Deep insertion can cause air
swallowing and gastric distension
Must be repositioned every 8 hours to prevent breakdown
No advantages over nasal cannula
Simple masks
Made up of clear flexible plastic that can be moulded to fit patients face
Volume: 100-300 mL.
FiO2 40-60% at 6-10 L/min
Fits person’s face without much discomfort
Perforations, act as exhalation ports
Vents in the mask allow for the dilution of oxygen
Simple masks…
Indications: Medium flow oxygen desired, mild to moderate respiratory distress
When increased oxygen delivery for short period (<12 hrs)
Contraindications: Poor respiratory efforts, apnea, severe hypoxia
Advantage:
Less expensive (Rs 80/-)
Can be used in mouth breathers
Disadvantage Uncomfortable
Require tight seal
Donot deliver high FiO2
FiO2 varies with breathing efforts
Interfere with eating, drinking, communication
Difficult to keep in position for long
Skin breakdown
Simple masks…
Practical considerations: Pediatric and adult sizes
Select a mask which best fits from the child's bridge of nose to the cleft of jaw, and adjust the nose clip and head strap to secure in place
No pressure point or damage to eyes
Flow <4 L/min results in rebreathing and carbon dioxide retention
The FiO2 inspired will vary depending on the patient's inspiratory flow, mask fit/size and patient's respiratory rate
Oxygen (via intact upper airway) via a simple face mask at flow rates of 4-6 L/min does not require humidification Humidification may be indicated/appropriate for patients with
secretions retention, or discomfort
Some conditions (eg. Asthma), the inhalation of dry gases can compound bronchoconstriction
Partial rebreathing face masks
Simple masks with additional reservoir that allows the accumulation of the oxygen enriched gas for rebreathing
Allows for the initial portion of the expired gases containing little or no CO2 (rich in oxygen) to be collected in a reservoir while the remaining expiratory gases are vented to the atmosphere
Partial rebreathing face masks…
Fio2 35-60 % flow rates of 6 to 15 L/min
Flow rate must be sufficient to keepbag 1/3 to 1/2 inflated at all times
Minimum flow should be 6 L/min to avoid patient breathing large part of exhaled gases and rest of exhaled air exit through vents
6: 35%8: 45-50%10: 60%12: 60%15: 60%
Partial rebreathing face masks…
Indications: Relatively high FiO2 requirement
Contraindications: Poor respiratory efforts, apnea, severe hypoxia
Advantage: Inspired gas not mixed with room air Patient can breath room air through exhalation ports if
oxygen supply get interrupted
Disadvantage More oxygen flow doesnot increase FiO2 Interfere with eating and drinking
6: 35%8: 45-50%10: 60%12: 60%15: 60%
Non-rebreathing face masks
Face mask + oxygen reservoir + a valve at exhalation port + a valve between reservoir and mask
Patient inhales oxygen from the bag and exhaled air escapes through flutter valves on the side of the mask
Oxygen flow into the mask is adjusted to prevent the collapse of the reservoir (12 L/min)
It prevent the room air from being entrained
10-15 L/min, FiO2 90-100%
6: 55-60%8: 60-80%
10: 80-90%12: 90%
15: 90-100%
Non-rebreathing face masks…
Indications: High FiO2 requirement >40%
Contraindications: Poor respiratory efforts, apnea, severe hypoxia
Advantage: Highest possible FiO2 without intubation
Suitable for spontaneously breathing patients with severe hypoxia
Disadvantage Expensive (Rs 250/-)
Require tight seal, Uncomfortable
Interfere with eating and drinking
Not suitable for long term use
Malfunction can cause CO2 buildup, suffocation
Non-rebreathing face masks…
Practical considerations: To ensure the highest concentration of oxygen is delivered to the
patient the reservoir bag needs to be inflated prior to placing on the patients face
Ensure the flow rate from the wall to the mask is adequate to maintain a fully inflated reservoir bag during the whole respiratory cycle
Do not use with humidification system as this can cause excessive 'rain out' in the reservoir bag
Flow rate must be sufficient to keep bag 1/3 to 1/2 inflated at all times
Avoid kinking and twisting of reservoir
Check that vales and rubber flaps are working
Venturi masks or Air-entrainment masks
A Venturi mask mixes oxygen with room air, creating high-flow enriched oxygen of a settable concentration
It provides an accurate and constant FiO2 in range of 24-50%
Venturi mask is often employed when the clinician has a concern about CO2 retention
Venturi masks or Air-entrainment masks…
Dilutional masks
Work on Bernoulli principle
Oxygen is delivered through the jet nozzle, which increases its velocity
The high-velocity O2 entrains ambient air into the mask due to the viscous shearing forces between the gas traveling through the nozzle and the stagnant ambient air
FiO2 depends on size of entrainment ports, nozzle, flow rate
The larger the port, the more room air is entrained and lower the FiO2
Reliably provide 25-60% FiO2 at 4-15 L/min
3: 24%3: 26%6: 28%6: 30%9: 35%
12: 40%15: 50%
Venturi masks or Air-entrainment masks…
Indications: Desire to deliver exact amount of FiO2
Contraindications Poor respiratory efforts, apnea, severe hypoxia
Advantage: Fine control of FiO2 at fixed flow
Fixed, reliable, and precise FiO2
Doesnot dry mucus membranes
High flow comes from the air, saving the oxygen cost
Can be used for low FiO2 also
Helps in deciding whether the oxygen requirement is increasing or decreasing
Disadvantage Uncomfortable
Expensive (Rs 150/-)
Cannot deliver high FiO2
Interfere with eating and drinking
Venturi masks or Air-entrainment masks…
Practical considerations:
Oxygen must be humidified and warmed
Monitor FiO2 at flow rates ordered
Not effective for delivering FiO2 greater than 50%
To achieve the desired FiO2 use the diagram below
Appropriate air entrainment position for desired FiO2 the oxygen flow rate and total flow that will be delivered to patient when these settings are utilized
To ensure that the patient's ventilatory requirements are met the total flow must exceed the patient's minute ventilation
Oxyhood
Small, clear plastic hood to cover infant’s head or head and upper torso
Patient more accessibility without disturbing O2 delivery
For newborns and young infants
Correct size: That has enough room for baby’s head to fit comfortably and allow free neck and head movements without hurting baby
FiO2 80-90%, Flow 10-15 L/min
3-4 sizes are available; Too big: dilute the oxygen; Too small: discomfort and CO2 retention
Adequate flow of humidified oxygen ensures mixing of delivered gases and flushing out CO2
Oxygen gradient can vary as 20% from top to bottom. Continuous flow >6 L/min avoids this problem
Ensure the headbox has a gap all around the child’s neck, this is important in preventing the accumulation and re-breathing of CO2
Gas flow must be high enough to prevent re-breathing of CO2
Face tent/face shield
High flow soft plastic bucket
Well tolerated by children than face mask
10-15 L/min, 40% FiO2
Access for suctioning without need for interrupting oxygen
Oxygen tent
Clear plastic sheet that cover child’s upper body
FiO2 50%
Not reliable
Limit access to patient
Not useful in emergency situations
,
Continuous positive airway pressure
By applying underwater expiratory resistance
Indicated
When oxygen requirement >60% with a PaO2 of <60 mmHg
Clinical parameters and general conditions also act as guiding criteria
CPAP reduce work of breathing, increases FRC and helps maintain it, recruit alveoli, increase static compliance, and improve ventilation perfusion ratio
Continuous positive airway pressure…
Methods: Underwater (indigenous/bubble ,
commercial)
Ventilator
Used in Early ARDS, acute bronchiolitis,
pneumonia
It should be tried in spontaneously breathing child who does not require emergency intubation prior to conventional ventilation
Can be used in early, incipient or frank respiratory failure
Continuous positive airway pressure…
Humidification add to the cost
Water vapors condense in tubing
Block
Trickle into airways: collapse, pneumonia
Single tube may not be compatible (commercially available binasal prongs)
High flow nasal prongs
Humidified high flow nasal prong (cannula) oxygen therapy is a method for providing oxygen and continuous positive airway pressure (CPAP) to children with respiratory distress
HFNP may reduce need for NCPAP/intubation, or provide support post extubation
At high flow of 2 L/kg/min, using appropriate nasal prongs, a positive distending pressure of 4-8 cmH2O is achieved
This improves FRC and reduces work of breathing
Because flows used are high, humidification is necessary to avoid drying of respiratory secretions and for maintaining nasal cilia function
MOA: application of mild positive airway pressure and lung volume recruitment
High flow nasal prongs…
Indications Respiratory distress from bronchiolitis, pneumonia, congestive heart failure
Respiratory support post extubation
Weaning therapy from CPAP or BIPAP
Respiratory support to children with neuromuscular disease
HFNP can be used if there is hypoxemia and signs of moderate to severe respiratory distress despite standard flow oxygen
Contraindications Blocked nasal passages/coanal atresia
Trauma/surgery to nasopharanyx
Complications Gastric distension
Pressure areas
Pneumothorax
High flow nasal prongs…
Equipment Oxygen and air source
Blender
Flow meter <7Kg : standard 0-15L/min flow meter
>7Kg: high flow oxygen flow meter, 50L/min flow
Humidifier (Fisher and Paykel MR850)
Circuit tubing to attach to humidifier Children <12.5kg: small volume circuit tubing
Children ≥12.5kg: adult oxygen therapy circuit tubing
Nasal cannula to attach to humidifier circuit tubing (size to fit nares comfortably)
Water bag for humidifier
Nasogastric tube
High flow nasal prongs…
Set up of equipment
Appropriate size nasal cannula and circuit tubing
Connect nasal cannula to adaptor on circuit tubing, and connect circuit tubing to humidifier
Attach air and oxygen hoses from blender to air and oxygen supply
Connect oxygen tubing from blender to humidifier
Attach water bag to humidifier and turn on to 37C
High flow nasal prongs…
Set up of equipment… Prongs should not totally occlude nares
Start the HFNP at the following settings: Flow rate
≤10Kg 2 L/kg/min >10Kg 2 L/kg/min for the first 10kg + 0.5L/kg/min for each kg above
that (max flow 50 L/min) Start off at 6L/min and increase up to goal flow rate over a few minutes to
allow patient to adjust to high flow
FiO2 Always use a blender, never use flow meter off wall delivering FiO2 100% Start at 50-60% for bronchiolitis and respiratory distress
High flow nasal prongs…
HFNP Improves the respiratory scale score Oxygen saturation Patient's COMFORT scale Reduce need for mechanical ventilation
Children with respiratory distress treated with high-flow nasal cannula. J Inten Care Med 2009High-flow nasal cannula oxygen therapy for infants with bronchiolitis: Pilot study.J Paediatr Child Health. 2014High-flow nasal cannula (HFNC) support in interhospital transport of critically ill childrenIntensive care med 2014High-flow nasal prong oxygen therapy or nasopharyngeal continuous positive airway pressure for children with moderate-to-severe respiratory distress? Pediatr Crit Care, 2013High-flow nasal cannula therapy for respiratory support in children. Cochrane Database SystRev.2014 Mar 7;3:CD009850Reduced intubation rates for infants after introduction of high-flow nasal prong oxygen delivery. Intensive Care Medicine. 2011
Hyperbaric oxygen
The goal is to deliver extremely high partial pressure of oxygen, >760 mmHg
Indications: Smoke inhalation
CO poisoning
CN poisoning
Thermal burns
Air embolism
Clostridium myenecrosis
Osteomyelitis (refractory)
Compromised skin grafts
Radiation injury
Acute traumatic ischemia/acute crush injury
Severe decompression sickness
Necrotizing fasciitis
Hyperbaric oxygen
Requires specialized equipment and personnel with intensive care unit skills and knowledge of the physiology and risks unique to hyperbaric oxygen exposure (CNS and Pulmonary)
Cost, unavailability
Hyperbaric oxygen…
The half-life of COHb is about five hours breathing 21% O2 at ambient pressure, a little more than one hour breathing 100% O2 at ambient pressure, and 30 min breathing 100% O2 at 3 atm of pressure
Heliox
Heliox is a gas mixture of helium and oxygen: low density
Obstructive lung diseases (bronchiolitis, acute bronchial asthma) In spontaneously breathing patients with asthma, heliox
decreases PaCO2, increases peak flow, and decreases pulsus paradoxus
There may be benefit related to the combination of heliox with aerosol bronchodilator delivery in patients with acute asthma
Heliox reduce resistance with upper airway obstruction (post extubation stridor)
Heliox…
Care must be taken to administer heliox in a safe and effective manner
To avoid administration of a hypoxic gas mixture, it is recommended that 20% oxygen/80% helium is mixed with oxygen to provide the desired helium concentration and FIO2
If an FIO2 requirement >40%, the limited concentration of helium is unlikely to produce clinical benefit
When using an oxygen-calibrated flow meter for heliox therapy, it must be remembered that the flow of heliox (80% helium and 20% oxygen) will be 1.8 times greater than the indicated flow
Heliox…
For spontaneously breathing patients, heliox is administered by face mask with a reservoir bag
Y-piece attached to the mask allows concurrent delivery of aerosolized medications
Sufficient flow is required to minimize contamination of the heliox with ambient air: 12 to 15 L/min
Administration during mechanical ventilation can be problematicDensity, viscosity, and thermal conductivity of helium affect the delivered tidal volume and the measurement of exhaled tidal volume
Measurement of delivered oxygen
Oxygen analyser or FiO2 meter
Sensor digitally convert sensed concentration into reading
Quality and accuracy of sensor is most important
Expensive part
Calibration with every use
The oxyhood is ideal place, can be used within masks held at moth or nose
Monitoring
Oxygen should not be administered without an objective assessment of its effect
Oxygen therapy should be used without wasting time and thought
Further therapy, amount, duration can then be formulated
FiO2 of 40-60% is adequate in most situations, 100% needed during resuscitation
Increasing requirement of FiO2 to maintain same SpO2 is an omniuossign
Children should be nursed in manner that makes them most comfortable
Mothers can be the best administrator of the oxygen
A frightened and agitated mother result into frightened and agitated child
Spend some time to explain the situation
Monitoring…
Vital signs (hourly) HR RR (including level of distress) BP Temperature SpO2
Breathing pattern Level of consciousness and responsiveness Color ABG
SpO2 >92% and PaO2 > 60 mmHg are acceptable
Monitoring…
Check and document oxygen equipment set up at the commencement of each shift and with any change in patient condition
Hourly checks should be made for the following:
oxygen flow rate
patency of tubing
humidifier settings (if being used)
Monitoring…
Document Day and time oxygen started
Method of delivery
Oxygen concentration and flow
Patient observation
Oronasal care and nursing plan
Oxygen is a drug and requires a medical order
Each episode of oxygen delivery should be ordered on the medication chart
Humidification
Humidification: Addition of heat and moisture to a gas
Rationale:
Cold, dry air increases heat and fluid loss
Medical gases including air and oxygen have a drying effect on mucous membranes resulting in airway damage
Secretions can become thick & difficult to clear or cause airway obstruction
In some conditions e.g. asthma, the hyperventilation of dry gases can compound bronchoconstriction
Indications:
Patients with thick copious secretions
Non-invasive and invasive ventilation
Nasal prong flow rates of greater than 2 L/min (<2 years) or 4 L/min (>2 years)
Facial mask flow rates of greater than 5 L/min
All high flow systems require humidification
Patients with tracheostomy
Humidification…
Fisher & Paykel MR 850 Humidifier
Invasive Mode: Delivers saturated gas as close to body temperature (37 degrees, 44mg/L) as possible. Suitable for patients with:
Nasal Prongs
Invasive Ventilation
Tracheostomy attachment or mask
Non-Invasive Mode: Delivers gas at a comfortable level of humidity (31-36 degrees, >10mg/L). Suitable for patients receiving:
Face mask therapy
Non-invasive ventilation (CPAP/BIPAP)
Humidification…
Humidifier should always be placed at a level below the patient's head
Water levels of all humidifiers should be maintained as marked to ensure maximum humidity output
Condensation will occur in the tubing of heated humidifiers. This water should be discarded in a trash contain and never returned into the humidifier
Inspired gas temperature should be monitored continuously with an inline thermometer when using heated humidifiers
The thermometer should be as close to the patient as possible
Warm, moist areas such as those within heated humidifiers are breeding grounds for microorganisms (especially Pseumomonas)
The humidifier should be changed every 24 hours
Weaning
Depend on clinical and lab parameters
SpO2 is important
High flow and concentration should be gradually lowered while monitoring
Low flow and concentration can be continued without ill effects for long time
Adverse effects
Oxygen being combustible, fire hazard and tank explosion
Catheters and masks can cause injury to the nose and mouth
Dry and non-humidified gas can cause dryness and crusting
Long term oxygen therapy: proliferative and fibrotic changes lungs
In acute conditions, high FiO2 lead to the release of various reactive species which attack the DNA, lipids, and SH containing proteins
Infections
Adverse effects…
CO2 Narcosis : In patients with chronic respiratory insufficiency----hypercapnea
Respiratory centre relies on hypoxemia to maintain adequate ventilation
Oxygen supplementation can reduce their respiratory drive, causing respiratory depression and a further rise in PaCO2 resulting in increased CO2 levels in the blood
Monitoring of SpO2 or SaO2 informs of oxygenation only. Therefore, beware of the use of high FiO2 in the presence of reduced minute ventilation
Pulmonary Atelectasis/absorption atelectasis
Pulmonary oxygen toxicity : High concentrations of oxygen (>60%) may damage the alveolar membrane when inhaled for >48 hours resulting in pathological lung changes
Retrolental fibroplasia: An alteration of the normal retinal vascular development, mainly affecting premature neonates (<32 weeks gestation or 1250g birthweight), visual impairment and blindness
Adverse effects…
Signs and symptoms of oxygen toxicity Nonproductive cough Nausea, vomiting Substernal chest pain Fatigue Nasal stuffiness Headache Sore throat Hypoventilation Nasal congestion Dyspnea
Low concentration oxygen therapy
Reserved for children at risk of hypercapnic respiratory failure Advanced cystic fibrosis and non cystic fibrosis brochiectasis
Severe kyphoscoliosis or severe ankylosing spondylitis
Severe lung scarring caused by TB
Musculoskeletal disorders with respiratory weakness
Overdose of opioids, benzodiazepines, or other drugs causing respiratory depression.
Uncorrected cardiac defects.
Until blood gases can be measured, initial oxygen should be given using a concentration of 28% or less, titrated towards a SpO2 of 88-92%
Oxygen safety
Oxygen support combustion (rapid burning). Due to this the following rules should be followed: Do not smoke in the vicinity of oxygen equipment
Do not use aerosol sprays in the same room as the oxygen equipment
Turn off oxygen immediately when not in use. Oxygen is heavier than air and will pool in fabric making the material more flammable. Therefore, never leave the nasal prongs or mask under or on bed coverings or cushions whilst the oxygen is being supplied
Do not use any petroleum products or petroleum byproducts e.g. petroleum jelly/Vaseline whilst using oxygen
Do not defibrillate someone when oxygen is free-flowing
Oxygen safety…
Oxygen cylinders should be secured safely to avoid injury and damage to regulator or valve
Do not store oxygen cylinders in hot place
Do not drag or roll cylinders
Do not carry a cylinder by the valve or regulator
Do not hold on to protective valve caps or guards when moving or lifting cylinders
Do not deface, alter or remove any labeling or markings on the oxygen cylinder
Do not attempt to mix gases in an oxygen cylinder or transfer oxygen from one cylinder to another
Take home message
Oxygen therapy saves life The selection of an appropriate oxygen delivery system
Clinical condition Patient's size and needs Therapeutic goals
Risks and hazards Advantages far outweighs the risks Hypoxia more dangerous than correctly delivered oxygen
Humidification Monitoring and proper documentation Donot forget to taper oxygen Use but do not abuse oxygen
References
http://www.rch.org.au/rchcpg/hospital_clinical_guideline_index/Oxygen_delivery/
Bateman, N.T. & Leach, R.M. (1998). ABC of Oxygen - Acute oxygen therapy. BMJ,
September 19; 317(7161): 798-801.
Ricard, J. & Boyer, A. "Humidification during oxygen therapy and non-invasive
ventilation: do we need some and how much"? Intensive Care Med (2009) 35: 963-965
Oxygen Therapy: Important Considerations. Indian J Chest Dis Allied Sci 2008; 50: 97-
107
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