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RSPT 1410 Oxygen Administration Devices Part 3

Cairo: Chapter 3, p. 64-78 Wilkins: Chapter 38, p. 872-891

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High-flow Devices

•  High-flow Nasal Cannula –  AquinOx, Comfort Flo, Vapotherm

•  Delivery of high flow oxygen via facemasks creates compliance issues –  Facemasks cover the entire mouth and nose

preventing eating and talking and removing them can lower oxygen saturation levels

–  Facemasks can be difficult to fit, can become dislodged during sleep, and cause undue stress

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High-flow Devices

•  A better way to administer high flow oxygen therapy is through a nasal cannula –  The nares can typically only tolerate up to

______ L/min due to the cold and dry composition of oxygen

–  Flows higher than 6 L/min can be too uncomfortable to endure and could possibly cause trauma over long periods of time

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High-flow Devices

•  With the newer high-flow cannulas, patients can tolerate high flow oxygen therapy directly through the nose, due to the systems’ ability to provide ______________ and ______________ oxygen

•  For example, the AquinOx provides –  High flow oxygen delivery from ____ to ____ L/min –  A flow rate dependent temp range of 33°C to 40°C –  Relative humidity of ____% to _____% –  Single patient therapy per unit

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HFNC - What It Does

•  In the past, it was thought that FiO2 would plateau at 6-8 L/min

•  Recent studies show FiO2 increase over the tested range of 10-30 L/min

•  The gas must be ______________ –  Body core temperature –  100% relative humidity

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HFNC - What It Does

•  Possible Benefits –  Increased FiO2

–  Oxygen at BTPS can add significant moisture to the airways • Stabilizing and protecting effect • Enhances ciliary movement & mucus clearance

–  May flush anatomic deadspace

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HFNC - What It Does

•  Possible Benefits –  Creation of low levels of ______________

• Useful in treating neonates and in some cases of adult sleep apnea

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HFNC – How is it Used?

•  In place of NRB masks –  Clinical report: CHF pts in the ED had higher SaO2s

with a 20 L/min HFNC

•  A method to avoid CMV –  Clinical report: pts with mean SaO2s of 88% and with

mean RR of 25 avoided CMV –  Clinical report: one hospital had a 51% decrease in

CMV

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HFNC – How is it Used?

•  To deliver ______________ and ______________

•  To improve exercise tolerance in asthmatics and COPD pts

•  Traumatic and post-op ______________ •  To treat AOP •  To help lung transplant pts exercise and tolerate

pre-conditioning prior to surgery

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HFNC – Set-Up

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HFNC – How It Works

•  Breathing gases are introduced at the gas input port on the AquinOx™ Humidification Chamber

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HFNC – How It Works

•  The pressurized gas flows over two orifices –  The first, causes a

suction that siphons sterile water from the reservoir through the up tube into the AquinOx™ Humidification Chamber

–  The second, causes a suction through the secondary tube that is connected to the center lumen of the Delivery Tube

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HFNC – How It Works

•  As the sterile water is aerosolized, some particles collect in a shallow layer at the base of the chamber

•  The layer of water is kept warm as aerosolization continues

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HFNC – How It Works

•  Aerosolized molecules circulate over the layer of warmed water, pick up heat, and are delivered down the Delivery Tube through the two outer lumens

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HFNC – How It Works

•  The warmed molecular and particulate humidification flow over a hollow porous media

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HFNC – How It Works

•  The suction caused by the secondary tube in the chamber, captures rainout, and suctions particulate back into the chamber initially through the porous media and then through the center lumen

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HFNC – How It Works

•  Only molecular humidification is delivered to the patient through the high flow nasal cannula.

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High-flow Devices

•  Air-entrainment masks –  also known as ______________ masks or Venti-

masks –  consist of mask, O2 jet and air entrainment ports –  due to a pressure drop and “drag”, O2 pulls in air

through entrainment ports –  amount of air drawn in, and therefore FiO2,

depends on O2 flowrate, the size of the O2 jet and the size of the entrainment ports

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High-flow Devices

Venturi Principle

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High-flow Devices

•  Two methods –  fixed O2 jet size; variable entrainment port size –  fixed entrainment port size; variable O2 jet size –  both methods use known air:O2 ratios to deliver a

______________ FiO2

–  air:O2 ratios can also be estimated –  If the air:O2 ratio is known, total _____________

can be estimated

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Approximate Air:O2 Ratios

FiO2 Air:O2 Total Parts*

1.0 0:1 1

.70 .6:1 1.6

.60 1:1 2

.50 1.7:1 2.7

.40 3:1 4

.35 5:1 6

.30 8:1 9

.28 10:1 11

.24 25:1 26

*Total parts X O2 flow = Total flow estimate

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Air:O2 Ratios

O2

100

Air

20

60%

O2

100

Air

20

air:O2 = 40:40 or 1:1

40 40

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Total Flow

If the air:O2 ratio is known, total flow can be estimated:

total parts X O2 flow = total flow estimate

Ex: FiO2 = 0.4; air:O2 = 3:1; O2 flow = 12 L/min

Ex: FiO2 = 0.6; air:O2 = 1:1; O2 flow = 8 L/min

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Enclosures

•  One of the oldest approaches to oxygen therapy

•  Create a controlled O2 ______________ •  Some enclosures can create an entire

controlled environment: O2, temperature, humidity

•  Now used mainly with infants and children

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Tents

•  Once, common method for adults and children

•  Today, used almost exclusively with children, who, in most cases, will not wear a facial appliance

•  Used to provide a controlled ______________ inside a ______________

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Tents

•  Most common type is the “______________ ” tent which also provides cooling and high humidity

•  Cooling is provided by a refrigeration unit that is capable of temperatures approximately 10 degrees F below room temperature

•  ______________ is provided by an aerosol generator

•  Tents are used primarily to provide pediatric aerosol therapy to children with croup or cystic fibrosis

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Tents

•  Major problem with tents is that frequent opening and closing of the canopy can cause wide fluctuations in ______________ concentration and ______________

•  In larger tents, O2 flows of _________ L/min can only provide approximately _________% oxygen

•  Other hazards include fire if certain items are allowed in the tent

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Tents

•  Devices that are electrically powered should not be allowed in the tent; and of course, no open flames, etc.

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Hoods

•  Best method of providing controlled O2 therapy to ______________

•  The “oxyhood” covers only the infant’s head, leaving the body free for nursing care

•  Oxygen is delivered to the hood by either a heated nebulizer or a blending system with a heated humidifier

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Hoods

•  O2 flow should be set at a minimum of _____ L/min to prevent accumulation of CO2 and depending on the size of the hood, O2 flows of 10-15 L/min may be needed to maintain stable oxygen concentrations

•  Higher flows should not be used because they are not necessary and may create harmful ______________ levels

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Hoods

•  With premature infants, gas should be warmed and not directed over the infant’s face as low temperatures or convection cooling can cause heat loss and cold stress

•  Gas temperature should be set to maintain a neutral thermal environment (N ���TE)

•  NTE for newborns over 2500 gm is 30oC •  NTE for newborns under 1200 gm is 35oC

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Incubators

•  Incubators are clear, usually Plexiglas, enclosures used to create a total environment, O2, temperature and humidity

•  Humidity is provided usually by an aerosol generator

•  O2 can be provided through a heated humidifier or by direct connection to a flowmeter which can limit delivered oxygen concentration to ________%

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Incubators

•  However, the best way to control delivered O2 is with a hood

•  Incubators are not as popular as they once were, but are still one of the best methods of providing a neutral thermal environment for stable infants

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Which Delivery Device?

•  A wide variety of devices is available and there is usually not just one best approach

•  Physicians may not always know what devices are available or what they can do - RCPs should be involved from the initial set-up and consultation and be responsible for oversight of the therapy

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Which Delivery Device?

•  Use the three Ps –  purpose –  patient –  performance

•  Purpose –  general purpose is to raise the FiO2 sufficiently to

correct hypoxemia –  some patients may have specific problems to be

addressed

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Which Delivery Device?

•  Patient - assess key factors –  severity and cause of hypoxemia –  patient age –  level of consciousness –  presence of artificial airway –  stability of ventilation

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Which Delivery Device?

•  Performance –  look at categories, i.e. fixed/variable performance,

low/high flow, etc. –  pair that with patient acuity –  critically ill patients generally need stable, more

precise FiO2 control –  less acutely ill generally will need lower, less exact

FiO2s