Overheating leading to patient airway burns. Inadvertent overfilling of humidifier by ... Burns to caregivers from inadvertently touching heated metal surfaces ... – PowerPoint PPT presentation
Absolute Humidity - amount of water vapor actually present in the air (expressed in mg/liter). Sometimes called water vapor content.
Maximum Absolute Humidity - amount of water vapor that the air can hold. Sometimes called water vapor capacity.
varies directly with temperature
Relative Humidity - the mathematical comparison of the above two. Content divided by capacity
3 Essential Information for Doing Calculations of Relative Humidity
The Maximum Absolute Humidity at body temperature is 44 mg/liter
This is sometimes called Body Humidity
Any Relative Humidity less than Body Humidity is called the Humidity Deficit
4 ANSI Guidelines
10 mg/L for Normal patient
30 mg/L for intubated patients
5 Indications for Humidifying and Warming of Gases
To humidify dry inspired gases
To overcome the humidity deficit when the upper airway is bypassed (trached patients or those with endotracheal tubes)
Less common indications
treatment of hypothermia
treatment of bronchospasm caused by cold air
6 Equipment Used to Humidify Gases
Bubble Diffusion Humidifiers
7 Factors Affecting Performance of Bubble Humidifiers
Time of contact between gas the water
Surface area available for evaporation to occur
Temperature of the gas
8 How Flow Lowers Water Temp 9 Typical Wick Type Humidifier 10 Fisher-Paykel Wick Humidifier 11 Puritan-Bennett Cascade 1 12 Puritan-Bennett Cascade 2 13 Hudson-RCI Conchatherm 14 Characteristics of Heated Humidifiers
Water can be heated to maintain high humidity output
Temperature can be sensed downstream from the unit so that water temperature can be adjusted to maintain correct gas temperature (like thermostat at home)
Heated wires can be employed to prevent condensation in tubing from gas cooling
15 Why Wick Type Humdifiers Are Popular
Produce high vapor output even at very high gas flows (gt100 l/m)
Do not produce any water particles
Low risk of producing nosocomial infections
Have ability to utilize heated wire circuits
Have continuous-feed water systems
16 Hazards Problems Associated with Heated Humidifiers
Overheating leading to patient airway burns
Inadvertent overfilling of humidifier by therapist
Increased airway resistance created by pooling of condensate in circuit
Burns to caregivers from inadvertently touching heated metal surfaces
17 Artificial Noses
Types of Heat Moisture Exchangers
Simple condensors
Hygroscopic Condenser Humidifiers (HCF)
Hydrophobic Condenser Humidifiers
Act by recycling exhaled heat moisture
Ideal unit should be able to produce at least 30 mg/l - Most produce 20 - 30 mg/l
18 Problems With HMEs
Increase in airflow resistance (particularly when mucus enters unit)
Drying thickening of secretions can become a problem
Must be removed when administering in-line medication aerosol treatments
Lose efficiency in patients with high minute volumes (gt10 l/m)
19 Why HMEs Have Become Popular?
Significant cost savings can be realized compared to a standard ventilator circuit using a heated humidifier
Less therapist time needed to drain condensed water from circuit
Greater simplicity
However, in some cases heated-wire circuits may be actually cheaper than the HME
20 Bland Aerosol Therapy
Indications for
Tx of laryngotracheobronchitis (croup)
Tx of sub-glottic edema
Post-extubation edema
Post-operative management of upper airway
Presence of bypassed upper airway
Need for sputum induction
21 Contraindications to Bland Aerosol Therapy
Bronchospasm (evidence of current disease)
Asthma or Chronic Bronchitis patients who c/o SOB
History of airway hyperresponiveness
Those with a hx of asthma or other obstructive lung disease
22 Hazards and Complications of Bland Aerosol
Wheezing associated with bronchospasm
Infection
Overhydration
Patient discomfort
Caregiver exposure to contagious aerosols
Noise
23 Types of Nebulizers Used for Bland Aerosol Therapy
Large Volume Jet Nebulizers
Ultrasonic Nebulizers
24 Schematic of Large Volume Jet Nebulizer 25 Schematic of Ultrasonic Nebulizer (USN) 26 Solutions Used for Bland Aerosol Therapy
Water - most irritating cheapest to use
Normal Saline (0.9 NaCl) - least irritating salt crystals can condense on water intake causing no aerosol to be produced
Hypertonic Saline - 5 or 10 - used only for sputum indutions
27 Delivery of Inhaled Medications
Delivery systems
MDIs
DPIs
Small volume jet nebulizers
aka HHNs SVNs wet nebs med nebs neb meds acrons
USNs
Specialized aerosol systems
28 Definitions
Aerosol
Penetration
Deposition
Stability
Retention
Clearance
29 Factors for Penetration and Deposition
Size of particle decides how far before depositing into the respiratory tract
30 Indications for aerosols
Deliver medications
Humidify gases
Mobilize secretions
31 Hazards
Overhumidification
Bronchospasm
Infection
32 Examples of MDIs 33 Characteristics of MDIs
Exact same dose each actuation
High initial aerosol velocity
Currently uses chloroflourocarbon (CFC) propellant. Hydroflouroalkanes (HFA) will replace CFCs pending final approval.
Without using a spacer - up to 80 of aerosol lands in the oropharynx or mouth
10 - 20 reaches small airways
administration is very technique dependent
34 MDI Accessory Devices
Holding chambers or spacers
Improve ease of administration
Decrease oral-pharyngeal deposition
Improve distribution of the mist
Flow-triggered MDIs
Currently only Maxair (pirbuterol) is available
35 Optimal Technique for Using MDI
Shake MDI first (warm if cold)
Actuate into chamber
Inhale slowly deeply
Maintain a 10 second breath hold
Allow 30 seconds between actuation
36 Disadvantages of MDIs
Coordination can be a problem
Requires use of additional spacer
High oral-pharyngeal deposition
Easy for patients to overuse
Some medications can be quite expensive
Some patients can run out without realizing
37 Characteristics of DPIs
Always are breath actuated since no propellant is used
Easier to self-administer - no spacer needed
Not very many drugs are available in this form
At least as good as MDI in terms of deposition and drug response
Cant be used with young children in ventilator circuits
38 Brand Names
Rotahaler Albuterol
Spinhaler Intal
Turbuhaler Terbutaline
Advair Flovent and Salmeterol
39 Optimal Technique for Using DPI
Patient must use high inspiratory flows
Best not used if patient is having severe SOB
Breath holding is not critical
Medication should be stored in a low humidity environment
40 Disadvantages of DPIs
Some patients cant generate high inspiratory flows needed
Assembly of unit can be difficult for some
Difficult to give high doses
Some pharyngeal deposition is unavoidable
Not that many medications available in this form (currently)
41 Small Volume Nebulizers
Generally hold 2 - 6 ml of solution
Can be filled using unit-dose preparations or multi-dose vials
Generally require 4-8 l/m of flow to actuate
Can be driven with either oxygen or air
When using oxygen - FIO2 can be 40 - 90 !!
Should be used instead of MDI or DPI if patient is tachypneic
42 Disadvantages of SVNs
Too complex for some patients to use
Requires assembly periodic cleaning
Not easily portable like the MDI or DPI
Not all medications are available
No steroids currently available for SNV administration
43 Specialized Medication Nebulizers
Respigard II - filters exhaled gas - delivers very small particles (1-2 microns)
Circulair - Uses a reservoir bag to conserve medication - enhances aerosol delivery
Continuous HEART Nebulizers - used for continuous drug administration (1-3 hours)
SPAG unit- used for administration of ribavirin
44 Small Volume Ultrasonic Nebulizers
Produce very dense mists at very high outputs
Compact units portable easy to use
Used for delivery of undiluted medications (bronchodilators antibiotics)
Some units can be powered by cigarette lighter adapter present in a car
45 Problems with USNs
Expensive to purchase
Prone to breakdown
Not all mediations are available in multi-dose or unit dose forms
Medication must be manually added to unit prior to use
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