Nebulizers and humidifiers IN ANAESTHESIA.pptx

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1. Nebulizers and humidifiers IN ANAESTHESIA

2. NEBULIZERS A nebulizer emits water in the form of aerosol mist Water vapor + particulate water Pneumatically driven (gas- driven ,jet ,high pressure, compressed gas ) Ultrasonic devices Both can be heated Used to deliver drugs

3. Pneumatic nebulizer Works by pushing a jet of high pressure gas in to a liquid Inducing a shearing forces and breaking water in to fine particles High flow of gas – should placed in fresh gas line

4. Ultrasonic nebulizer Produces fine mist by subjecting liquid in to a high frequency , electrically driven ,ultrasonic resonator Oscillation frequency determines size of droplets No need for a driving gas Creates denser mist than pneumatic Used in fresh gas line or inspiratory limb

5. Hazards Nebulized gas obstruct HME or filter in breathing system Overhydration If droplets not warmed ,hypothermia occurs Infection Pneumothorax – if nebulizer connected directly to ET tube

6. Advantages Can deliver gases saturated with water without heat

7. disadvantages Costly Pneumatic nebulizers requires high gas flows Ultrasonic nebulizers require electricity – electrical hazards Frequent draining of tubes Blocking of tubes

8. Humidifiers Humidity – amount of water vapor in a gas Absolute humidity –mass of water vapor present in given vol of gas –mg/L Relative humidity –amount of water vapor in particular temp ,expressed as percentage of amount that would be held if gas were saturated

9. Sources of humidity C02 absorbent – absorbent granules contain water , exothermic reaction of CO2 with absorbent releases water and produce heat Exhaled gases – rebreathing in tracheal tube,supraglottic airway device & connections to breathing system Moistening breathing tubes and reservoir bag Low fresh gas flow Coaxial breathing system

10. Active humidifiers –presence of external source of heat and water Passive humidifier –utilization of patient’s own temp and hydration to achevive humidification Vaporizer or vaporizing humidifier Passes a stream of gas over water(pass over ) Across wicks dipped in water (blow-by) Through water (bubble or cascade ) Heated or unheated Unheated cannot deliver more than 9mgH2O/L

11. A disposable or resusable humidification chamber –holds water A heating element to warm the water Humidified gas passes to the patient through inspiratory tube Tube is not heated –water condense inside the tube &water trap needed Some humidifiers has heated wire in the tube Heating and insulating insp tube –better control of temp and humidity Temp moniter at patient end of circuit controls amount of heat for proper humidification

12. use In circle system ,heated humidifier placed in insp limb down stream of unidirectional valve using a accessory breathing tube If filter is used, placed upstream of humidifier to prevent clogging of water Must be located lower than the patient – avoid water running down the tube in to pt’s resp tract Heater wire should not be bunched , stung evenly along the length of tube Delivery tube coverd with sheets, blankets, other material

13. Advantages Most heated humidifiers delivering saturated gas at body temp or above even with high flow most effective humidification than HME

14. Disadvantages Bulky and complex High maintenance cost , eletrical hazards Little protection against heat loss during anaesthesia

15. Unheated Disposable ,bubble through devices used to increase humidity in oxygen supplied to pts via face mask or nasal canula Simple containers containing distilled water through which oxygen is passed and gets humidified Max humidity achievd 9mgH2O/L

16. Hazards infection Breathing system problems –sticking valves ,leaks ,disconnections ,obstructed gas tube ,clogged filters Adding humidifier change volume and compliance of breathing system – delivery of less accurate tidal vol Water aspiration Over hydration Thermal injury Increased work of breathing Monitoring interferance Equiptment damage or malfunction

17. PASSIVE HUMIDIFIERS Simplest designs are HME ( heat & moisture exchanger ) Artificial nose ,condenser humidifier ,nose humidifier , swedish nose ,regenerative humidifier Vary in size , shape, dead space Have a port to attach gas sampling line or resp gas moniter Placed between ET tube and breathing circuit

18. Increases resistance to air flow during both insptn and exptn Removed when administration of aerosolized medications May be used in tracheostomised patients Should be replaced if contaminated with secretions Should be appropriate size for patients tidal vol Connecting more than one in series will improve performance but care should be taken increase in dead space is not excessive for particular patient

19. Indications To increase inspired heat and humidity during both short and long term ventilation Transporting intubated patients To supply supplemental oxygen to intubated patient – by connecting oxygen tubing to gas sampling port

20. Advantages Inexpensive Easy to use Small ,light weight ,easy to use Silent in operataion Do not require water /external energy source/ temp moniter No overhydration /hyperthermia /burns /electrical source