Oxygen Delivery Systems

 

Low flow systems

Do not meet the patients inspiratory flow demands.

Normal inspiratory flow rate is 25 to 30 L/min

Additional flow  comes from RA

 

q       Nasal Cannula and Nasal Catheters

Delivers 24 to 44% oxygen at 1 to 6 L/min

1 = 24

2 = 28

3 = 32

4 = 36

5 = 40

6 = 44

 

·        Nasal Catheters

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

 

·        Transtracheal Catheters

Delivers low flow rates (1 to 3 L/min) directly to the trachea through a small incision

Requires less oxygen (lower flows) because the upper airway deadspace is bypassed

**Can develop infection and irritation  at site and there is a risk of accidental removal

**If pt becomes SOB or has increased **Flush with saline**

**Cleaning Rod         **reposition

 

 

·        Cannulas

better tolerated

may be humidified but often not if run @ less than 5 L/min

there are two types of O2-conserving cannulas

-Nasal reservoir

reservoir just below the nose stores ~ 20 mL of O2

allows for lower flows because of increase O2 delivery

 

-Pendent reservoir

pendent stores O2

must exhale through nose

 

**HFNC -  6-15lpm

 

·        Simple masks

Delivers 35 to 55 % O2 at flows of 5 to 12 L/min

**Must never be used at flows less than 5 L/min to prevent rebreathing of CO2

 

·        Partial Rebreathing Masks

Delivers 35 to 60 % O2 at flow rates of 8 to 15 L/min

**Flow rate must be sufficient to keep bag 1/3 to 1/2 inflated at all times

 

·        Non-rebreathing Mask

Delivers 60 to 90% O2 at flow rates of 8 to 15 L/min (NBRC says 100%)

**Flow rate must be sufficient to keep bag 1/3 to 1/2 inflated at all times

Is equipped with a one-way valve that does not allow exhaled gas into the reservoir

One way valves are located on both expiratory ports of the mask to prevent RA entrainment

 

The percentage of O2 delivered by a low flow device is variable because RA is entrained.

FiO2 will vary depending on the patients RR, pattern and VT

Patients who have variable ventilatory patterns, RR >25 and VT that vary outside of 300-770mL, should not use a low flow system

 

 

High Flow Oxygen Systems

·        Methods for setting up high flow oxygen

1) air entrainment mask

2) mechanical aerosol systems

3) Gas Injection Nebulizer- need high flow flowmeters

4) High FiO2 Misty Ox- for FiO2 of .60+

5) Blender and titration system

 

High flow O2 systems provide all of the inspiratory flow required by the patient at consistent FiO2s

These devices are normally attached to nebulizers

(Venti-mask may or may not be)

 

·        Venturi Mask or air-entrainment masks

                        provide FiO2’s from 24 to 50%

Increasing flow will not alter FiO2 (precise)

The size of the entrainment port determines FiO2

The larger the port, the more RA entrained, the lower the FiO2

 

·        Aerosol Mask

Delivers 21-100% FiO2 depending on nebulizer setting

Flow rates of 8 to 15 L/min

On 100% the device will probably not meet flow demands.(>60%) (No air entrained so flow = flowmeter setting)

 

·        Face Tent

21% to 40% depending on nebulizer setting

Flow rates of 8 to 15 L/min

Used mainly for patients who can not tolerate a mask

 

·        T-Piece (T-tube, Briggs adapter)

21-100% depending on nebulizer setting

Flow rates of 8 to 15 L/min

Used on intubated or trached patients

Allows use 50 mL of reservoir tubing to maintain FiO2 Adequate flow is demonstrated by visible mist out of the reservoir

 

·        Trach Mask

35-60% O2 depending on nebulizer setting

Flow rates of 10 to 15 L/min

**Adequate flow shown by mist flowing out the exhalation port at all times

 

·        Oxygen Tent

21 -50% at flow rates of 10 to 15 L/min

Used mainly on children with croup or pneumonia

Problem with leakage

Fire hazard

 

·        Important Points

**High FiO2’s (>.60) may not meet the patient’s inspiratory flow demands

To insure adequate flow with stable FiO2’s, a special made high flow device should be used or two flowmeters set up to provide at least 40 L/min total flow

 

**A restriction, such as a kink, or water in the tubing, causes back-pressure into the nebulizer. This decreases the amount of RA entrained and INCREASES the delivered FiO2.

**Increasing flow on a high flow device will not increase FiO2, only total flow

 

·        Head box-

small, clear plastic enclosures over infant’s head or head and upper torso

Head boxes allow for a higher oxygen concentration and more accessibility to patient without disturbing oxygen delivery.

. Best not to entrain room air into head box because of noise and microorganism introduction (Blender)

 

·        air: oxygen entrainment ratios:

.60 1:1

.50 1.7:1

.40 3:1

.35 5:1

.30 8:1

 

BiPAP

BiPAP stands for Bilevel Positive Airway Pressure.

Bilevel means that the pressure varies during each breath cycle.

Inspiration can be triggered by flow or time and is cycled by time or flow.

·        IPAP = inspiratory positive airway pressure    8 to 20 cm H2O

·        EPAP = expiratory positive airway pressure   2 to 10 cm H2O

 

The BiPAP aids oxygenation and ventilation in cases of sleep apnea or ventilatory muscle fatigue.

It has also been applied to prevent the more invasive procedures of intubation or tracheostomy.

 

Humidifiers

Low-Flow Humidifiers (unheated)

·        Pass-Over Humidifiers

Gas passes over the surface of H20, picking up moisture

 

Because bubblers are water reservoir, they can support the growth of Pseudomonas aeruginosa.

Improperly handled humidifiers have been linked to nosocomial respiratory infections with  this pathogen

 

·        High Flow Humidifiers (heated)

-Heated Pass-over

directs gas over a reservoir of heated water.

 

-Diffuser Cascade

A more efficient design of the low flow diffusion (bubbler) humidifier.

Besides being heated, the area for gas water interface is increased by use of large diffusion tower. Temp, surface, contact time effect amt

 

-Bubble through wick

utilize  a paper/cloth wick through which the mainstream flow must pass.

 

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 wye 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.

 

-Heat moisture exchangers (HME, artificial nose).

Exhaled heat and moisture are collected and made available to warm and humidity the following inspiration. Change Daily**

 

Types of Nebulizers

·        Jet (Mechanical)

Uses a high pressure gas stream (Bernoulli and Venturi) to produce an aerosol

--50% of output is in the 0.5-3 micron range

 

·        Babington Nebulizer

Uses the principle of a jet stream of gas being directed through a thin film of continually flowing liquid spread across a rounded surface

 

**Important Points on Nebulizers

--Heated nebulizers are the greatest source of contaminated moisture to the patient.

--Should be changes every 12 to 24 hours

--Jet and capillary tubes should be kept free of build-up  to provide adequate mist and allow fluid to be drawn up the tube adequately.

--Water level must be maintained to assure optimal aerosol output

--Water in the aerosol tubing will increase the % oxygen delivered to the patient

 

 

 

 

Manual Resuscitators

Used for:

Rescue breathing

Hyperinflation

To transport patients who require ventilation

Ideal stroke volumes:  Adult—800mL avg. Infant—200mL

 

·        Safety devices

-Non-rebreathing valve

-Universal adapter 22-mm OD and a 15-mm ID

-Pressure relief device (25cmH20)

 

·        Self inflating bags

Can be used without gas flow

Usually reusable but disposable are available

Require reservoir to deliver 100% oxygen

 

·        Flow-inflating bags

Depends on a gas source

Must have a tight seal to inflate

Uses a flow-control valve to regulate pressure inflation

 

To achieve the highest FiO2 levels:

Always use a reservoir attachment, if available

Use the highest flow available (10-15 l/min)

Slower rates with long bag refill time, allows for higher FiO2’s to be delivered

Smaller volumes also deliver greater FiO2’s

 

Hazards:

Leaks because of inadequate seals or leaky cuffs

Equipment malfunctions—sticky valves, etc

Poor ventilation technique

 

**Troubleshooting Manual Recesitators

If the valve jams at high flows, reduce the flow to between 8-15 L/min. If this does not relieve the problem, get another bag.

Accumulation of secretions or vomit in the valve may result in sticking with diversion through the pop-off. Cleaning the valve should resolve the problem in permanent or disposable bags.

 

Positive Pressure Ventilation

·        Four standard criteria for initiating mechanical ventilation

apnea

acute ventilatory failure

impending ventilatory failure

hypoxemic respiratory failure

 

 

Both volume-cycled and pressure-cycled volume delivery modes.

Many older transport ventilators may operate on a time-cycled mode.

 

·        Pressure-cycled

A peak inspiratory pressure (PIP) is applied and the pressure difference between the ventilator and the lungs results in inflation until the peak pressure is attained, and passive exhalation follows.

 

            -Pressures are constant - volumes vary

 

The delivered volume with each respiration is dependent on the pulmonary and thoracic compliance as well as airway resistance

This requires close monitoring and may limit the usefulness of this mode in emergency department patients.

 

·        Volume-Cycled

-Inhalation proceeds until a set tidal volume (TV) is delivered and is followed by passive exhalation.

-Since the volume-cycled mode ensures a constant minute ventilation, it is a common choice as an initial ventilatory mode.

-A feature of this mode is that gas is delivered with a constant inspiratory flow pattern, resulting in peak pressures applied to the airways higher than that required for lung distension (plateau pressure).

 

-Volume delivered is constant - pressures vary

 

Ti + Te = TCT

TCT = 60/BR

BR= 60/TCT

Vt = flow rate x Ti / 60 sec.

 flow rate = Vt / Ti x 60 sec.

 Ti = Vt x 60 sec / flow

 

 

 

Excessive airway pressures may be generated, resulting in barotrauma.

Close monitoring and use of pressure limits are helpful in avoiding this problem.

 

 

 

·        High Frequency Ventilation

Use of supraphysiologic ventilatory rates above 60 rpm

Use of tidal volume smaller than the anatomic dead space

 

-Types of HFV

 

High frequency positive pressure ventilation (HFPPV) - refers to the delivery of small tidal volumes through an insufflation catheter or endotracheal tube with circuitry having a minimal compressible volume.

The characteristic rate is 60 - 100 cycles per minute with inspiration taking 20% to 30% of the total cycle time.

VT used are between 3 and 5 ml/kg

 

 

 

 

High Frequency Jet Ventilation

During High Frequency Jet Ventilation (HFJV), gas is propelled into the lungs at a very high velocity through a jet catheter

Rates of 100-600

Can be used in conjunction with CMV

 

High Frequency Oscillatory Ventilation

Oscillating device forces small impulses of gas into and out of the airway

Exhalation is said to be active in high-frequency oscillation

Can deliver 1 to 60 Hz.

I Hz equals 60 cycles

5 Hz = ~300 bpm

VT less than VD

 

·        Manipulate Blood Gases with High Frequency:

A.HFPPV-

> to decrease PaCO2:

- decrease frequency with same Ti

- increase Ti with same frequency

B.HFJV-

>To decrease PaCO2

- dec. frequency with same PIP and Ti

- inc. driving pressure with same frequency and Ti

C. HFOV-

- increase delta P = increase ventilation

- increase MAP = increased oxygenation

 

Artificial Airways

 

·        Oropharyngeal Airway (bite block)

Used on unconscious patients to prevent the tongue from obstruction the airway

Two main types

-Berman is hard plastic with an “I-beam” design

-Guedel is hollow type that has opening in the middle

**Should never be taped in place, must be easily removable in cause of vomiting

**Gagging or fighting

Improper insertion causing tongue to block the airway

 

·        Nasopharyngeal Airway (trumpets)

maintains a patent airway by pushing the tongue forward off the posterior portion of the oropharynx

better tolerated by semi-conscious or conscious patients

used to allow nasotracheal suctioning with decreased trauma

 

make sure the patient has no history of broken nose, deviated septum or other nasal obstructions

make sure water soluble or water based lubricant is used to minimize trauma to the mucosa

 

·        ET Tubes

Indications for ET tubes:

Patent airway (Upper airway obstruction)

Protect the airway

Facilitate suctioning

To assist in manual or mechanical ventilation

 

Hazards of ET tubes:

Infection

Trauma

vocal cord damage

laryngeal or trachea edema/damage

mucosal damage

Mechanical problems

tube occlusion

R mainstem intubation (>25 cm deep-orally)

·        Tube size

adult male  8 mm to 9 mm tube

adult female  7 mm to 8 mm tube

Endotracheal tubes (ETT) are sized by either the internal diameter (2.5 to 10 mm) or the external diameter with sizes 32-42 French (Fr).

 

·         Laryngoscope

The must be held with the left hand. (Good for us lefties)

Most adults require a (curved) Macintosh # 3 or 4 blade or a straight Miller #3

 

·        Tracheostomy Tubes

Preferred for long-term

When upper airway obstruction prevents intubation

ET tube is removed only as trach tube is ready to be inserted.

Easier to stabilize, suction and tolerate

Inner Cannulas - Fewer hazards and minimal airway resistance

Obturator  - is used for insertion into stoma

Cuff  - (if present) is inflated

A Tracheal Button  - is a rigid cannula placed stoma after removal of a trach tube.  *For Stoma only Pt.

It is generally kept closed during the day to be unobtrusive, and opened at night to eliminate sleep apnea.

 

Suctioning the Airway

·        Suctioning removes air as well as secretions from the lungs.

·        Hypoxemia can be minimized by hyperoxygenating the patient 1 to 2 minutes

·        Usually done with 100% if possible (NRB)

·        Patient should be hyperoxygenated between suction attempts

·        Suctioning should take less than 15 seconds per pass

 

Other types of catheters

Yankauer used to suction oropharynx

Coude (directional tip) used to guide catheter into the left mainstem

 

 

 

·        Vacuum Systems

Central (wall) vacuum systems connect to a vacuum regulator via a quick connect or DISS connector

**Infants 60-80     **Peds 80-100          **Adults 100-140

 

Cylinders

Most Chrome molybdenum                     *2200 psig

 

·        “H” cylinder holds 244 cu ft (6900 L)

·        “E” cylinder holds  22 cu ft (622 L)

·              (There are 28.3 L in 1 cu ft.)

·        Cylinder color codes

oxygen- green or white(international)

nitrogen- black cyclopropane- orange

helium- brown heliox- brown and green

air-yellow, black and white, black and green

carbon dioxide- gray

carbogen- gray and green

ethylene- red

nitrous oxide- light blue

·        Valves on cylinders allow connection to only one type of gas regulator:

-American Standard Safety System (ASSS) for high pressure connections on large cylinders

Pin Index Safety System (PISS) for high pressure connection on small cylinder

Diameter Index Safety System (DISS) for low pressure (<200psi)

 

·        Cylinder duration:

E cylinder: # of minutes remaining = psig x 0.28

lpm

H cylinder: # of minutes remaining= psig x 3.14

lpm

 

·        Safety Relief Device

--A frangible disk which breaks to release gas pressure 

--A fusible plug that melts to release gas pressure in the event of fire

 

Before attaching regulator, open cylinder valve slowly for discharge of gas then close. **Place washer on “E”

 

·        Regulators

-Reduce the gas pressure to a workable level   (50psi)

--two gauges:  cylinder pressure and pressure of the gas

Single stage pressure regulators reduce to 50 PSI in one step and has one pop off

Double stage pressure regulators reduce  to a working level in two steps. 150 and then to 50 with two safety relief devices

 

--Regulators may be preset or adjustable

>Preset is preset at 50 psig

>Adjustable can vary pressure output

 

·        Flowmeters

 

>Uncompensated flowmeters will inaccurately indicate flow in the presence of backpressure.

--They  do not work when positioned on their side

>Compensated flowmeters accurate in the presence of back pressure.

--Still position dependent

>Bourdon Gauge Flowmeter

--is accurate when laid on it’s side

 

Air Compressor

n      Provide medical air through portable or large medical piping systems

Three types

n      Piston is used for large piping systems.

n      Diaphragm is used for portable compressors

n      Rotary is used for nebulizers and IPPB

 

Oxygen Concentrators

Flow can be adjusted from 1 to 10 L/min but FiO2 is fixed at 40% at high flows

 

**Trouble-shooting tips

n      The molecular sieve type unit delivers dry gas so humidity must be added

n      The permeable plastic membrane units have a condensation jar that must be emptied

n      Both units have filters that should be changed monthly

n      If a patient says that he or she cannot feel any gas coming out of the cannula, have the patient place the prongs in a glass of water. If no bubbling is seen, have the patient check for disconnects.

n      If the concentrator is malfunctioning, have the patient turn it off and switch to a backup oxygen cylinder

 

Liquid Gas Systems

A thermos-like tank (about 40" tall) filled with liquid oxygen.

 

n      A smaller lightweight portable unit can be filled off the reservoir so the patient can take the oxygen with them when they leave home.  (HELIOS)

n      Liquid oxygen is especially good for active people who need to be out of the home on a frequent basis.

 

Oxygen Blender

n      50 psi gas source for each oxygen and air

n      The blender has pressure regulating valves and mixing controls that allow FiO2s of 21-100% at flows of 2 to 100 L/min

**Audible alarm sounds if inlet pressure decreases (Reed valve)

 

 

 

 

IPPB

augmenting lung expansion, **Treat Atelectasis**

 delivering aerosol medication

 

n      Properly position patient (High-Fowler’s position)

 

If air does leak through the nose, place nose clips or have them pinch their nostrils.

Adjust the pressure setting to assure a comfortable breath that is about 25% more than their normal tidal volume.

Continuously coach the patient regarding deep breathing and an intermittent inspiratory hold. (3 sec)

 

**Troubleshooting**

n      The machine will not cycle

>>Sensitivity set incorrectly <# to>sensitivity

>>No gas source

>>Leaks in tubing

>>Leak around mouthpiece

>>Check flow control on Bird Mark 7

n      The patient can not cycle the machine off

>>Usually a sign of a leak.

>>Check all connections, tubing, mask, mouthpiece, ETT, etc

>>If using the PR-2, turn on the terminal flow to help >>compensate for a leak and check the Bennett valve stuck?

>>Check the expiratory valve function

n      During inspiration, the needle stays negative for the first half of the breath

>>Too little flow. Increase flow

>>The machine cycles on during the expiratory phase (chatters)

>>Decrease the machines sensitivity

>>Ensure that the rate control is turned off (PR-2)

>>Expiratory timing control is off

 

Incentive Spirometer

q       Is best strategy for the prevention of atelectasis

q       Also used to treat atelectasis

q       Should be done hourly for about 10 breaths.

q       Intolerated then use alternate (PEP or IPPB)

 

Chest Physical Therapy

 

q       Percussion

Percussion is also referred to as cupping, or clapping.

Applies kinetic energy to the chest wall and lung to dislodge secretions

Should be performed over each area for 3 to 5 minutes

 

q       Vibration

Vibration involves the application of a fine tremorous action (manually performed by pressing in the direction that the ribs and soft tissue of the chest move during expiration) over the draining area

 

q       High Frequency Chest Wall Oscillator

nonstretchable vest is worn.

Children as young as 3 years are able to use the vest. A treatment lasts 20-30mins (depending on the size of the chest).

The vest is done sitting upright.

 

q       PEP Therapy

>This pressure allows air to enter behind areas of mucus obstruction and keeps the airways open during exhalation.

>Used for 15-20 minute intervals, 3-4 times a day.

>The patient should be instructed to inspire a larger than normal tidal volume and actively exhale but not forcefully.

>Exhalation is 2-3 times longer than inspiration

>Expiratory pressures range from 10-20 cmH20 at mid-exhalation

>PEP resistance levels are adjustable. 10 to 20 cmH20

 

q       Flutter Valve

Exhaling produces oscillations of pressure and airflow which vibrate the airway walls (loosening mucus)

Positive expiratory pressure averages 10-25 cmH20

Treatment time is about 20 minutes.

 

Helium/Oxygen Therapy

 

Two common heliox mixture are

q       80% He and 20% O2

q       70% he and 30% O2

q       The correction factor for the 80:20 mixture is 1.8

q       The correction factor for the 70:30 mixture is 1.6

q       non-rebreather or ventilated

 

Wright Respirometer

Uses rotating vane

Measures patient's tidal volume and minute volume. Can also record FVC

 

Art Line

Multiple sampling of arterial blood, particularly in the mechanically ventilated patient

v     Pulse pressure

>Normally 80-100 mmHg

**Trouble Shoot

v     Damped pressure tracing

>Occlusion of catheter tip by clot

>Catheter tip resting on wall of vessel

v     Clot in transducer or stopcock

>Air bubbles in line

>Abnormally high or low pressure readings

>Improper calibration

>Improper transducer position (level of heart)

v     No pressure reading

>Improper scale

>Transducer not open to catheter

 

The Swan-Ganz catheter is an important aid in monitoring and treating the critically ill patient.

v     NBRC term - Flow directed pulmonary artery catheter

v     Mixed Venous

It is valuable in assessing cardiac, pulmonary, and fluid status in patients experiencing shock, CHF, pulmonary hypertension, pulmonary edema, and the use of high PEEP levels.

 

Disposable Drainage Unit

v     The Pleur-evac is a three-chambered system

v     Approximately 1 to 2 cm of water is put in the water seal chamber (middle)

v     Water rises toward the patient side of the chamber during inspiration and returns to the other side on expiration

 

Important points:

Water level in the water seal bottle will fluctuate with with normal breathing. If there are no fluctuations, a blockage of the tube should be suspected.

Obstructed chest tubes may lead to tension pneumos

 

v     Occasional bubbling is seen in the water-seal bottle

v     A constant bubbling in the water seal bottle may indicate air leak; new or excessive bubbling must be reported immediately.

v     The system should always be lower than the chest to prevent backflow

v     The system should be airtight

v     Additional suction is ordered at < -15 mmHg

v     Chest tube is usually kept in 1 to 2 days once the lung has re-expanded

 

Oximetry

Can determine the pulse and presence of perfusion as well as SaO2.

 

v     Factors affecting the accuracy of oximeters include:

Intensity of ambient light

Patient and probe motion

The transmitted light intensity

Nail polish

Low perfusion or pulse intensity

 

Transcutaneous Monitoring

 

Transcutaneous Electrodes measure gas tension through the skin.

Trouble Shooting??

 

Metered Dose Inhalers

Self-contained device that uses a propellant (CFC) to deliver a dose of medication

“Spacers” are available for improved deposition

 

v     Dry Powder Inhalers (DPI)

>disperses dry powdered aerosol

>Requires faster inhalation than MDI

 

Bronchoscopy

A procedure that involves direct visualization of the patient’s trachea and bronchi.

v     Types of bronchoscopes:   Rigid and Flexible fiberoptic

- Rigid used on foreign body aspiration

 

Sterilization/Disinfection Techniques

Heat is frequently used to eliminate microorganisms.

v     Boiling (100°C) kills within 10 minutes.

v     Steam under pressure (Autoclaving) (121°C for 15 min at 15 psi)

v     Pasteurization -  hot water bath at 63-70ºC for 30 minutes

v     Ethylene oxide is the gas most frequently used for sterilization.

v     Gluderaldehyde submersion for 10hrs at room temp.  At 60 degrees Celsius only needed for 1 hour.