RC20 Chpater 38

What factors determine air to oxygen ratio

...

FiO₂ greater than ____ presents a significant risk of absorption atelectasis

0.50

the three specific clinical objectives for oxygen therapy

1) correct documented or suspected acute hypoxemia 2) decrease the symptoms associated with chronic hypoxemia 3) decrease the workload hypoxemia imposes on the cardiopulmonary system

what is the most common liter flow and resultant FiO2s for nasal cannula

1-5 L/min, there is a 4% increase in FiO2 for every 1 L/min so the pt's FiO2 from room air is .21 and if @ 2 L/min, will be .21 + .08 = .29

If a patient is on 40% oxygen delivered thru an air entrainment nebulizer and the patient has a minute ventilation of 12 what is the minimum input flow that is required

10 L/min

what is the air to oxygen ratio of 60% oxygen?

1:1

What is the recommended maximum dose of nitric oxide

20ppm

What is the range of FiO₂ for oxygen tent

40 to 50

In large tents oxygen input flow od 12 to 15 L/min can provide only __________% oxygen levels

40 to 50%

Limit patient exposure to 100% oxygen to less than ____________ hours

24

Most AEMs can be set to deliver no more than ______ % oxygen

50

If a patient is on 3 L/min of oxygen, How much FiO₂ is the patient receiving

33%

approximate FiO2 achieved with simple mask

35-50% @ 5-12 L/min

approximate FiO2 achieved with partial rebreathing mask

35-60% @ 6-10 L/min

what is the air to oxygen ratio for 40% oxygen?

3:1

If a patient is on 5 L/min of oxygen, How much FiO₂ is the patient receiving

41%

The total output flow of an air entrainment nebulizer set to deliver 40% oxygen ranges from

48 to 60 L/min

High FiO₂ is acceptable if the concentration can be decreased to 70% with in 2 days and 50% or less in ______ days

5

What is the minimum flow setting for a mask

5 L/min

What is the minimum for low that a high flow oxygen device must be set up

60 L/min

what is the minimum flowrate that high flow systems should be capable of delivering?

60 L/min

What is the minimum flow that should be set to prevent accumulation of CO2 in hoods

7 L/min

Hyperbaric therapy at three add-ons how much dissolved oxygen is in the plasma

7 mL/dL

Modern disposable non rebreathing mask normally do not provide much more than approximately _____ % oxygen

70

approximate FiO2 achieved with nonrebreathing mask

70+%

How often should you recheck a patient that has had an acute myocardial infarction

72 hours

1 atmosphere =

760 mm Hg or 101.32 KPa

Low flow oxygen systems provide supplemental oxygen directly to the airway at the flow of

8 mL/ min or less

FiO₂ at 100% what is the half life of carboxyhemoglobin

80 minutes The half life of carboxyhemoglobin under hyperbaric oxygenation at 3 atm is only 23 minutes

The American Academy of pediatrics recommends keeping arterial PO₂ in an infant less than _____ mm Hg as the best way to minimize the risk of ROP

80 mm Hg

since an O2 flowmeter will be inaccurate when regulationg He flow, what conversion factor must be used to determine flowrate?

80/20 = 1.8 70/30 = 1.6

What concentration should He/O2 be?

80/20 or 70/30

What SpO₂ must a patient have in order to be discontinued from oxygen

92%

When is it a humidifier used

When the input flow is greater than 4 mL/min

How do you know if flow of 10 L per minute is enough for a patient

When the patient takes in a breath a little mist should still be in exhalation ports

Physiologic Responses of Healthy Individuals to exposure to 100% inspired oxygen 30 to 72 hours

Decreasing diffusing capacity

describe high flow systems

Also known as fixed performance devices High flow systems supply a given oxygen concentration at a flow that equals or exceeds the patients inspiratory flow, thus ensuring a stable FiO2 In order to meet variations in patient's inspiratory demands, a high flow device should provide at least 60 L/min total flow There are two major categories of high flow devices: -Air Entrainment Systems -Blending Systems

Physiologic Responses of Healthy Individuals to exposure to 100% inspired oxygen 25 to 30 hours

Decreasing lung compliance Decreasing exercise PO₂

Physiologic Responses of Healthy Individuals to exposure to 100% inspired oxygen 12 to 24 hours

Decreasing vital lung capacity

Erin entrainment system

Direct the high-pressure oxygen source through a small nozzle or jet surrounded by air entrainment ports

Toxic side effects of nitric oxide

Acute pulmonary edema For or paradoxical respond Methemoglobinemia Increased left ventricular filling pressure complications of certain cardiac anomalies Rebound hypoxemia Pulmonary hypertension

How to increase FiO₂ of air entrainment nebulizers

Added open reservoir to expiratory side of T tube Provide inspiratory reserve with one way expiratory valve Connect to or more nebulizers together in parallel Set nebulizer to low concentration bleed in oxygen analyze and adjust Use a commercial door flow system

A patient has acute on chronic episode. When is it safe to decrease oxygen or when are they considered stable

Adequate oxygenation of these patients generally means SaO₂ of 85% to 90% with PaO₂ of 50 to 70 mm Hg

what are the key features of an oxygen tent?

Air conditioned or cooled by ice to provide a comfortable temperature within a plastic sheet canopy, Major problem is that frequent opening and closing of the canopy causes wide swings in oxygen concentration, and because of variability of FiO2 and inability to produce high FiO2's tents are used primarily to provide pediatric aerosol therapy to children with croup or cystic fibrosis

what is the effect of down stream flow resistance on air entrainment devices?

Any resistance to flow distal to the jet will result in less air entrained, therefore the delivered oxygen concentration will be increased. However total flow will also be decreased, therefore if the total flow does not meet the patients needs the patient will inhale room air and the delivered oxygen concentration may actually be lower than what is being delivered.

Why have air entrainment nebulizers been the traditional device of choice for delivering oxygen to patients with artificial tracheal airways

Because of added humidification and heat control

What should be considered when an air entrainment devices cannot provide a high enough oxygen concentration or flow

Blending system, this system allows precise control over both FiO₂ and total flow output

What are some issues with an oxyhood

CO₂ build up Loud Loss of heat difficult to clean or disinfect

Exposure to high PO₂ first damages the

Capillary endothelium, then interstitial edema follows

What are the clinical signs of severe hypoxemia in the nervous system

Confusion Distressed appearance Blurred vision Tunnel vision Loss of coordination In paired judgment Slow reaction time Manic-depressive activity coma

For patients with chronic hypoxemia, this increased workload over the long-term can lead to right ventricular failure which is known as

Cor pulmonale

What are the three clinical objectives of oxygen therapy

Correct documented or suspected acute hypoxemia Decrease symptoms associated with chronic hypoxemia Decrease the workload hypoxemia imposes on the cardiopulmonary system

how do air entrainment systems operate

Directs a high-pressure oxygen source through a small nozzle or jet surrounded by air entrainment ports As the oxygen flows through the restricted orifice the velocity increases. The increased velocity pulls in or entrains room air through the air entrainment port

what are the advantages of a nasal cannula

Easy to use on adult children and infants Disposable Low-cost Well-tolerated

How often should you recheck a patient using an oxygen hood

Every hour

How many hours must you recheck a patient with COPD

Every two hours

What are some possible complications of oxygen therapy

Fire hazard Oxygen toxicity Retinopathy of prematurity

What is the main problem with oxygen tents

Frequent opening and closing of the canopy causes wide swings in oxygen concentration

Describe an oxygen blending system

Has 2 gas sources Separate pressurized air and oxygen sources are input, and the gases are mixed either manually or with a precision valves

characteristics of partial rebreather mask

Has a 1 liter reservoir bag which increases the reservoir volume therefore increases the FiO2 over a simple mask The bag is open to the flow of exhalation gases and does allow the first portion of the exhaled gases to enter the reservoir, thus the rebreathing of air At flows between 6 - 10 L/min FiO2's are between 35 - 60 %

Is an oxyhood considered a low flow or high flow oxygen delivery system

High flow

What type of low flow device can operate as a high flow FiO₂ device

High flow nasal canula, which creates an increase in airway pressure

Blending system

Separate pressurized air and oxygen sources are input, and the gases are mixed either manually or with the precision valve

What is the therapeutic benefit of inhaled nitric oxide

Improved bloodflow to ventilated alveoli The result is a reduction in intrapulmonary shunting, improvement in arterial oxygenation, and a decrease in pulmonary vascular resistance and pulmonary arterial pressure

Common problems with low flow oxygen delivery systems

In accurate flow System leaks or obstructions Device displacement Skin irritation

What factors determine downstream resistance

In the presence of flow resistance distal to the Jets, the volume of air entrained always decreases. With less air being in trained, total flow output decreases, and the delivered oxygen concentration increases Increase downstream flow resistance causes back pressure

Nitric oxide

Is a colorless odorless highly diffusible and lipid soluble free radical that oxidizes quickly to nitrogen dioxide in the presence of oxygen

Hyperbaric oxygen therapy

Is a therapeutic use of oxygen at pressures greater than one atmosphere

Retinopathy of prematurity

Is an abnormal either condition that occurs in some premature are low birth weight infants to receive supplemental oxygen. An excessive blood oxygen levels causes retinal vasoconstriction, which leads to necrosis of the blood vessel

What may cause the pop valve on the humidifier to make a squealing sound

It may be kinked Obstruction distal to humidifier Flow is set too high Obstructed naris

What happens when the Venti mask ports are partially occluded

Less air is entrained Decrease total flow Increase oxygen

characteristics of a nonrebreather mask

Like the partial rebreathing mask it has a 1 liter reservoir bag, however it also has a series of one-way valves. A one way valve between the bag and mask prevents exhaled gas from returning into the bag. One way valves placed on the exhalation ports will prevent entrainment of room air In concept a leak-free mask with competent valves and adequate flow should deliver 100% source gas. A truly fixed performance situation is difficult to achieve, however the nonrebreather mask will provide the highest FiO2 of the reservoir mask, with FiO2 around 70+%

A physician orders that you manually mix gases. 45% oxygen with a flow of 60 L/min. How do you calculate?

Liter flow: 42% LIters of oxygen: 18%

What formula is used to calculate the air to oxygen ratio?

Liters of air divided by the liters of O2 = (100-%O2) / (%O2-21) %O2 = [(Air flow x 21) + (O2 flow x 100)] / total flow

What are the three basic designs of oxygen delivery system

Low Flow Systems Reservoir systems High Flow Systems

How do you prevent the rebound effect of nitric oxide

Make it oxide after used for more than a few hours should always be slowly weaned off over ours. When a nitric oxide is finally discontinued, FiO₂ frequently needs to be initially increased then slowly reduce to baseline over one or two hours

What are some disadvantages of an oxygen mask

Must be removed for eating Uncomfortable Aspiration hazard

When does a high flow system yield a set FiO₂

Must exceed patients flow demands and less then or equal to 35%

Low flow oxygen delivery systems include

Nasal cannula Nasal catheter Trans tracheal catheter

Which mask gives 60% FiO₂

Nombre breather

Physiologic Responses of Healthy Individuals to exposure to 100% inspired oxygen 0 to 12 hours

Normal pulmonary function Tracheo bronchitis Sub sternal chest pain

How do you calculate the oxygen and air settings to achieve a specific FiO2 and flow rate when manually blending O2 and air?

O2 flow = [Total flow X (O2% - 21)] / 79 Air flow = Toal flow - O2 flow Example: to manually mix air and oxygen to provide a pt with 50% O2 at a total flow of 60 L/min. O2 flow = (60x(50-21)) / 79 O2 flow = 22 L/min Air flow = 60 L/min - 22 L/min Air flow = 38 L/min So 22L of O2 and 38L of air should be blended together

the 4 major harmful effects of oxygen therapy

O2 toxicity, depression of ventilation, retinopathy of prematurity, absorption atelectasis

All oxygen delivery systems should be checked at least

Once per day

How much FiO₂ varies depends on

Oxygen input flow The mask volume The extent of air leakage Patient's breathing pattern

What are the indications for oxygen therapy

PaO₂ less than 60 mm Hg SpO₂ less than 90% Acute care situations in which hypoxemia is suspected Severe trauma Myocardial infarction Short-term therapy or surgical intervention post anesthesia recovery

Prolonged exposure to oxygen shows what on an x ray

Patchy infiltrates appear on chest radiographs and usually are most prominent in the lower lung fields

define reservoir systems

Provides a mechanism to gather and store oxygen between patient breaths. Classified as a variable performance device, however can be a fixed performance device as long as the stored volume equals or exceeds the patient's tidal volume and there are not any air leaks. Consist of the reservoir cannula and reservoir masks.

The effects of inhailed nitric oxide are limited to the

Pulmonary circulation

Oxygen therapy can reverse

Pulmonary vasoconstriction Decrease right ventricular workload

What does hypoxemia cause

Pulmonary vasoconstriction Pulmonary hypertension

What are some examples of reservoir systems

Reservoir cannulas Masks Non-rebreathing circuit

What are the clinical signs of mild to moderate hypoxemia in the nervous system

Restlessness Disorientation Headaches

The risk of absorption atelectasis is greatest in patient's breathing at low tidal volumes as a result of

Sedation Surgical pain Central nervous system dysfunction

Patient factors in selecting oxygen therapy equipment

Severity and cause of hypoxemia Patient age group Degree of consciousness and alertness Presence or absence of tracheal airway Stability of minute ventilation Mouth breathing versus a nose breathing patient

Three types of the reservoir masks

Simple mask Partial rebreathing mask Non-rebreathing mask

When a patient is breathing 100% oxygen, what is the earliest response

Sub sternal chest pain

What are clinical signs of mild to moderate hypoxemia in the cardiovascular system

Tachycardia Mild hypertension Peripheral vasoconstriction

What are the clinical signs of severe hypoxemia in the cardiovascular system

Tachycardia, with eventual bradycardia, and arrhythmia Hypertension and eventual hypotension

What are the clinical signs of severe hypoxemia in the respiratory system

Tachypnea Dyspnea Cyanosis

What are the clinical signs of mild to moderate hypoxemia in the respiratory system

Tachypnea Dyspnea Paleness

Nitric oxide has been approved for the treatment of

Term and near term neonates with hypoxic respiratory failure with associated pulmonary hypertension.

FiO₂ provided by air entrainment devices depends on two key variables

The air to oxygen ratio The amount of flow resistance downstream from the mixing site

What should you do if the patient is on a non-re breather and the bag completely deflates

The flow is inadequate, increase the flow

Oxygen toxicity primarily affects what

The lungs and the central Nervous system

The larger the intake ports and the higher the gas velocity at the jet

The more air is entrained

the toxicity of oxygen is caused by

The overproduction of oxygen free radicals

How do you select the proper oxygen device

The selection of the proper oxygen device is based on its purpose the patient and it's performance

What determines the air to oxygen ratio and the delivered FiO₂

The size of the jet and entrainment ports

Why is Heliox use

To decrease the work of breathing Heliox is less dense Decrease the respiratory rate, the level of just Pineo, and the need for intubation and mechanical ventilation in patients with reversible obstructive disorders

Oxyhood requires an AEN with tubing and a heater so

To no cause loss of heat to the infant

True of False High flow systems deliver oxygen and 100% or less

True

True or False Because they dilute source oxygen with the air, entrainment devices always provide less than 100% oxygen

True The more air they entrain, the higher is the total output flow, but the delivered FiO₂ is lower

What are the early signs of in pending CNS toxicity

Twitching Sweating Pallor Restlessness

When is hyperbaric oxygen therapy used

Two most common air embolism carbon monoxide poisoning

A well-designed oxygen protocol ensures the patient

Undergoes initial assessment Is evaluated for protocol criteria Receives the treatment plan that is modified according to need Stops receiving therapy as soon as it is no longer needed

What are the three basic ways to determine whether a patient needs oxygen therapy

Use of laboratory Measures to document hypoxemia A patients need for oxygen therapy can be based on the specific clinical problems or conditions Hypoxemia has many manifestations, such as tachypnea tachycardia cyanosis and distressed overall appearance

A simple mask does not have

Valves Reservoir bag High FiO₂

When oxygen therapy is given is should decrease what

Work of breathing

He's value as a therapeutic gas and the purpose?

based on the low density and is used to decrease the WoB in pts with large airway obstruction by decreasing the turbulence of flow in the airways which int urn requires a reduction in the driving pressure needed to move air flow past the obstruction

what are the key features of an oxygen hood?

best method for controlled oxygen therapy to infants, covers only the head so the rest of the body is free to be cared for, Oxygen is delivered to the hood via either a heated air entrainment nebulizer of a blending system with a heated humidifier, and a minimum flow of 7 L/min should be set in order to prevent accumulation of carbon dioxide

what is the cause and procedure for when the humidifier pop-off is sounding

cause & procedure obstruction distal to humidifier - find and correct obstruction flow is set too high - use alternative device obstructed naris - use alternative device

what is the cause and procedure for when there is no gas flow felt coming from the cannula

cause = flow meter not on or system leak procedure = adjust flow meter, check connections

characteristics of a simple mask

cover mouth and nose with the body of the mask gathering & storing O2 between pt breaths; exhaled air escapes through holes in its body. If O2 input is interrupted, air is drawn through these holes and around the mask edge. Flows of 5-12 L/min, minimum of 5 L/min to prevent rebreathing of CO2, FiO2 35-50%, chosen when moderate FiO2 are needed for a short time

Low temperatures or convection cooling produced by high flow devices over the head can cause

heat lost and cold stress

basic characteristics of a transtracheal catheter

deliver O2 directly into the trachea through a small bore catheter that is surgically inserted into the trachea; uses 40-60% less O2 flow than cannula so no humidification necessary; O2 builds up in trachea during expiration & is taken in during inhalation

What are the major complications of hyperbaric oxygen therapy

ear or sinus trauma Tympanic membranes rupture Alveolar over distention and pneumothorax Gas embolism CNS toxic reaction Pulmonary toxic reaction Fire Sudden decompression Reversible visual changes Claustrophobia Decreased cardiac

if no gas flow can be detected with the reservoir mask...

either the flowmeter is not on (so turn it on) or there is a system leak (check connections)

if the humidifier pop-off is sounding...

either there is an obstruction distal to the humidifier ( find and correct the obstruction), the input flow is too high ( omit humidifier if treatment is short term), or there is a jammed inspiratory valve ( fix or replace valve)

define cor pulmonale

enlargement of the right ventricle of the heart due to disease of the lungs or of the pulmonary blood vessels

what is the cause and procedure for when the pt is mouth breathing

habitual mouth breathing or blocked nasal passages - switch to a simple or venturi mask

what are the common problems with He therapy?

ineffective for aerosol delivery, coughing less effectived b/c of reduced turbulent air flow, distorted speaking, and hypoxemia because of adding high levels of O2 decreased the effectiveness of the He

what is the cause and procedure for when pt reports soreness over lip or ears

irritation or inflammation caused by appliance straps - loosen straps or place cotton balls at pressure pints or use an alternative device

if erythema develops over face or ears...

irritation or inflammation due to appliance or straps (provide skin carem use an alternative device, or place cotton balls on affected areas to act as a buffer between the skin and equipment)

What 2 factors affect the amount of air entrained?

jet size or orifice and the air entrainment port size

The oxygen provided by low flow device is always diluted with air, the result is a

low and variable FiO₂

What delivery system should be used with heliox

non re breather mask

how should heliox be delivered?

non-rebreather or simple mask

at what point is humidification needed for nasal cannula?

over 4 L/min

In premature infants cold stress can increase

oxygen consumption apena

nitric oxide therapeutic benefit

potent pulmonary vasodilator, by causing smooth muscle relaxation in the pulmonary capillary system. This improves blood flow to ventilated alveoli which helps reduce pulmonary vascular resistance

basic characteristics of low-flow systems

supply O2 @ 8 L/ or less, don't meet pt's inspiratory flow needs so pt draws room air resulting in low & variable FiO2 (amount depends on pt's inspiratory flow rate, tidal volume, and the O2 flow delivered)

The primary types of oxygen in closers used for infants and children are

tents Incubators hoods

if the patient is constantly removing mask....

the causes can be claustrophobia (use alternative device) or confusion (use restraints)

if the reservoir bag collapses when the patient inhales...

the flow is inadequate so increase the flow

In emergencies and which tissue hypoxia is suspected patient should be given

the highest FiO₂ possible, ideally 100% Clinical examples include respiratory or cardiac arrest, severe trauma, shock, carbon monoxide poisoning, and cyanide poisoning

what effect does the air entrainment port size have on the system?

the larger the air entrainment port the more air entrained so the lower the FiO2 and the greater the total output flow

what effect does the jet size have on the way the air entrainment system operates?

the smaller the jet the higher the velocity, the high the velocity the more air entrained so the lower the FiO2 and the greater the total output flow

if the reservoir bag remains inflated throughout inhalation...

there is either a large mask leak (correct leak) or the inspiratory valve is jammed or reversed (repair or replace the mask)

What is the overall goal of oxygen therapy

to maintain adequate tissue oxygenation while minimizing cardiopulmonary work

when is it approriate to use a blender system?

when air-entrainment devices cannot provide a high enough O2 concentraion or flow and if the power goes out and the treatment cannot be administered without the power being on