Chapter 1 Medicals Gas Therapy

In a single stage regulator pressure is reduced from

2200 psi to 50 psi in single step

In multistage regulators, pressure is reduced from

2200 to psi in steps (2200 psi – 700

psi – 50 psi)

What is Thorpe Tube Flowmeter

Used to regulate flow

Read flow in center of ball

Backpressure compensated is when

Ball jumps when flowmeter is plugged into wall

What is a Bourdon Flowmeter

Regulates pressure to control flow

Flow calibrated in liters per minute

Uncompensated: Back pressure will cause indicated flow to increase and actual flow will decrease

Can be used in any position; not affected by gravity

What is a Flow Restrictor

Gas passes through an orifice; this allows fixed amount of flow through the orifice

What is a fixed orifice

only one flow rate will be provided

What is an adjustable orifice

has several orifices providing several options for flow

Flow Restrictors: Variable orifice flow

restrictor

What is a Low flow (variable performance) delivers

an FIO2 of 0.22 to 0.80

Low flow (variable performance): FIO2 is affected by

inspiratory flow rate, tidal volume, respiratory rate, and flow rate of oxygen

Low-flow devices include:

Nasal cannula

Nasal catheter (no longer used)

Transtracheal catheters

Simple mask

Partial rebreather

Nonrebreather

What does High flow (fixed performance) do

Provides flow rate adequate to meet patients’ inspiratory flow needs

Delivers a FIO2 of 0.24 to 1.0

Examples of High flow (fixed performance)

Air entrainment mask

Incubators

Oxygen tents

Oxygen hoods

Common problems of Nasal Cannula

Nasopharyngeal-mucosal irritation

Twisting of connective tubing

Skin irritation

What are the Clinical Practice Guideline for Oxygen Therapy in the Acute Care Facility

Definition/description

Administration of oxygen at concentration greater than ambient air

Preventing symptoms and effects of hypoxia

What are the Indications for Clinical Practice Guideline: Oxygen Therapy in the Acute Care Facility

Documented hypoxemia

Suspected hypoxemia

Severe trauma

Acute myocardial infarction

Short-term therapy

What are the precautions and complications Clinical Practice Guideline: Oxygen Therapy in the Acute Care Facility

Suppression of ventilatory drive

Adsorption atelectasis

Bacterial contamination

Use with caution in patients with paraquat poisoning or those receiving bleomycin

Use low levels in patients receiving laser

bronchoscopy

What are the Limitations of Clinical Practice Guideline: Oxygen Therapy in the Acute Care Facility

Oxygen therapy has limited effectiveness in patients with anemia and circulatory impairment

Oxygen therapy should not be used as substitute for mechanical ventilation

Monitoring for Clinical Practice Guideline: Oxygen Therapy in the Acute Care Facility should be

with clinical assessment and PaO2 or SpO2

If FIO2 levels <0.40 of Clinical Practice Guideline: Oxygen Therapy in the Acute Care Facility the start of the therapy should be

Within 12 hours

If FIO2 levels >0.40 Clinical Practice Guideline: Oxygen Therapy in the Acute Care Facility the start of the therapy should be

Within 8 hours

In acute myocardial infarction Clinical Practice Guideline: Oxygen Therapy in the Acute Care Facility should be monitored

Within 72 hours

The diagnosis of chronic obstructive pulmonary disease (COPD) Clinical Practice Guideline: Oxygen Therapy in the Acute Care Facility should be monitored

Within 2 hours

In oxygen therapy, FIO2 is approximate

1 L/min – 0.24

2 L/min – 0.28

3 L/min – 0.32

4 L/min – 0.36

5 L/min – 0.40

6 L/min – 0.44

What are the Indications of Clinical Practice Guideline: Oxygen Therapy in Home or Alternative Care Site

Documented hypoxemia:

(PaO2 equal to or less than 55 torr when breathing room air)

(SpO2 equal to or less than 88% when breathing room air)

(Exceptions: a diagnosis of cor pulmonale, congestive heart failure, or hematocrit >56% allows for higher oxygen levels)

What are the Resources for Clinical Practice Guideline: Oxygen Therapy in Home or Alternative Care Site for Low-flow devices

nasal cannulas, transtracheal catheters, pulse delivery devices, reservoir nasal cannula

What are the Resources for Clinical Practice Guideline: Oxygen Therapy in Home or Alternative Care Site for High-flow devices

tracheostomy collars and T tubes

What are the Resources for Clinical Practice Guideline: Oxygen Therapy in Home or Alternative Care Site for Supply systems

concentrator, liquid system, or compressed gas cylinder

How should I Monitor Clinical Practice Guideline: Oxygen Therapy in Home or Alternative Care Site

Monitor SpO2 or PaO2 before starting therapy

Repeat measurement when it is indicated

What is Infection control for Clinical Practice Guideline: Oxygen Therapy in Home or Alternative Care Site

Low risk of infection when humidifier is not used

Equipment should be cleaned and disinfected on a regular basis

What is Definition/description and Indications for Clinical Practice Guideline: Selection of Oxygen Delivery Device for Neonatal and Pediatric Patients

Administration of oxygen to a neonatal or pediatric patient

Documented and Suspected hypoxemia

What are Contraindications of Clinical Practice Guideline: Selection of Oxygen Delivery Device for Neonatal and Pediatric Patients

Nasal cannulas and catheters are not appropriate for patients with nasal obstruction

Catheters are not appropriate for patients with facial trauma or neonatal patients

What are Hazards/precautions/possible complication of Clinical Practice Guideline: Selection of Oxygen Delivery Device for Neonatal and Pediatric Patients

ROP – keep PaO2 <80 torr

Avoid high oxygen levels with some types of congenital heart disease

Avoid oxygen therapy in patients being treated for paraquat poisoning or those receiving bleomycin

Changes in ventilatory pattern from cool gas directed at infant’s face

Skin irritation

Gastric distention

Increased risk of aspiration with masks

Limitations of Oxygen Therapy: Nasal cannula

Changes in minute volume affect delivered FI02

Prongs are difficult to keep in position

Maximum flow in infants is 2 L/min

Limitations of Oxygen Therapy: Nasopharyngeal catheters

Limited use due to its complexity

Avoid with excessive mucous drainage, mucosal edema, and deviated septum

Limitations of Oxygen Therapy: Transtracheal catheters

Not commonly used due to complexity of care

Limitations of Oxygen Therapy: Masks

Delivered FIO2 will vary

Confining; not well tolerated

Accuracy of air entrainment can be affected by resistance to flow

Limitations of Oxygen Therapy: Hoods

FIO2 will vary within the hood

Oxygen therapy may need to be interrupted during nursing care

Flows of at least 7 L a minute to wash out carbon

dioxide

Oxygen Conservation Devices: Transtracheal catheters

Lower flow rates since oxygen is delivered directly into the trachea

Risks include infection and obstruction

Require frequent care to prevent complications

Oxygen Conservation Devices: Reservoir nasal cannula

Available in mustache cannula or pendent cannula

Reservoir traps oxygen-rich gas from early portion of exhalation

Oxygen is inspired with next breath

Decreases flow rate of oxygen necessary to obtain required SpO2

Oxygen Conservation Device: Pulse demand oxygen delivery system

Delivers oxygen only during inspiration

Can be used with nasal cannulas, nasal catheters, and transtracheal oxygen catheters

Delivers flows equivalent to 1 to 5 L/min

Where does a Simple Oxygen Mask during inspiration, patient draws air from

Tubing

Reservoir in the mask

Ports in side of the mask

Simple Oxygen Mask delivers FIO2 of

0.35 to 0.50 at flows of 5 to

10 L/min

What is a Partial Rebreathing Mask

Includes reservoir bag, but there are no values

Delivers FIO2 of 0.40 to 0.60 at flows of 6 to 8 L/min

Bag must be one-third to one-half full during inspiration

What is a Nonrebreathing Mask

Includes mask with reservoir bag

Valve allows patient to pull oxygen from reservoir during inspiration

Same valve prevents patient from exhaling back into reservoir

Valve over exhalation ports on side of mask prevents air from being entrained during inspiration

Nonrebreathing Mask delivers an FIO2 of

0.60 to 0.80

Flow rates must be adequate to prevent excessive deflation during inspiration

What is an Air Entrainment Mask

Oxygen delivered through an orifice; this increases flow rate of gas

A decrease in pressure on other side of orifice

Causes air from atmosphere to be entrained

What are Oxygen Hoods

Used to deliver supplemental oxygen to infants

The FIO2 should be monitored at same level as infant’s nose

Noise levels inside hood can be problematic

What are Incubators

Regulate temperature, humidity, and FIO2 of infants’ environment

Include port to regulate FIO2 : (If port is open, FIO2 is 0.40 or less and If port is closed, FIO2 is 0.40 or higher)

FIO2 inside incubator can vary significantly due to opening chamber for nursing care

Hood inside incubator may be necessary to maintain consistent FIO2

Regulation of FIO2: Oxygen adder

Uses two flowmeters (one oxygen and one air) that blend two gases to obtain desired FIO2

FIO2 is determined using same ratios as air entrainment systems

Oxygen Blenders and Mixers do that following

Mixes 50 psig source of oxygen and air to obtain precise FIO2

Alarms signal failure of either compressed gas source

Pressure change of 10 psig will activate alarm

Hyperbaric Oxygen Therapy increases atmospheric pressure patient is exposed to with either

Continuous or intermediate use of 100% oxygen

Hyperbaric Oxygen Therapy: Clinical applications

Carbon monoxide poisoning

Smoke inhalation

Poor wound healing

Anaerobic infections

Thermal injuries

Skin grafts

Refractory osteomyelitis

The Physiologic effects of Hyperbaric Oxygen Therapy: Lung volumes

lung volumes decrease as pressure is increased

The Physiologic effects of Hyperbaric Oxygen Therapy: Alveolar and arterial partial pressure of oxygen

Will be increased as atmospheric pressure is increased; partial pressure of inspired gas will increase (Dalton’s law). Arterial partial pressure will increase as more oxygen is dissolved in the plasma (Henry’s law)

The Physiologic effects of Hyperbaric Oxygen Therapy: Gas temperature

kinetic activity of gases increases as gas pressure is increased; effects are minimized by regulation of rate of increase in pressure

The Physiologic effects of Hyperbaric Oxygen Therapy: Work of breathing

as barometric pressure is increased, density of a gas will increase. This will increase work of breathing. This will not affect most patients. Some patients will require ventilatory support when in a hyperbaric chamber

The Physiologic effects of Hyperbaric Oxygen Therapy: Vascular function

enhances growth of new blood vessels; this effect is useful in treatment of patients with skin grafts and poor wound healing

The Physiologic effects of Hyperbaric Oxygen Therapy: Immunologic function

improved function of leukocytes during hyperbaric oxygen therapy; the therapy also inhibits growth of some types of bacteria

What are Monoplace chambers

large enough to hold one person; entire chamber is filled with pressurized oxygen

What are Multiplace chamber

large enough to hold two or more patients; there is usually an attendant. Chamber is filled with compressed air, and patient wears hood filled with oxygen

Hyperbaric Oxygen Therapy: Monitoring devices

Transcutaneous oxygen monitoring provides evaluation of perfusion

Arterial blood gas analysis can be done in chamber

Indications for Hyperbaric Oxygen Therapy

Air embolism

Carbon monoxide positioning

Cyanide poisoning

Decompression sickness

Refractory anaerobic infection

Refractory osteomyelitis

Skin grafts

Thermal burns

Wound healing

What are the Contraindications for Hyperbaric Oxygen Therapy

Congenital spherocytosis

High fever

Hypercapnia (>60 torr)

Obstructive airway disease

Optic neuritis

Pneumothorax

Seizure disorders

Sinusitis

Upper respiratory tract infection

Viral infection

Nitric Oxide Therapy consists of

Used as a pulmonary vasodilator to treat persistent pulmonary hypertension on the newborn

Initial therapeutic dose is 5 to 80 parts per million

Commonly administered with INOmax

Helium-Oxygen Therapy is

low density of gas improves ability of gas to move around obstruction

can be administered through an endotracheal tube or well-fitted nonrebreather

Helium-Oxygen Therapy Clinical application

Exacerbation of asthma

Treatment of postextubation stridor

Treatment of refractory croup

Treatment of severe airway obstruction in chronic bronchitis and emphysema

Helium-Oxygen Therapy Available concentrations

80% Helium and 20% oxygen

70% Helium and 30% oxygen

60% Helium and 40% oxygen

What is Actual flow

due to low density of gas oxygen flowmeters are not accurate

Helium-Oxygen Therapy Correction factors used to determine actual flow rate of gas:

80:20 – 1.8 × liter flow

70:30 – 1.6 × liter flow

60:40 – 1.4 × liter flow

What is Carbon Dioxide (Carbogen) Therapy

Used to treat hiccups and carbon monoxide poisoning and in prevention of washout of CO2 during cardiopulmonary bypass

Supplied as 5% carbon dioxide and 95% oxygen or 7% carbon dioxide and 93% carbon dioxide

Monitoring Carbon Dioxide Therapy

Blood pressure

Patient pulse

Respiration

Mental status

If decreases are observed, therapy should be stopped immediately