NOTES FOR UNIT 11, HUMIDITY THERAPY

1. = Humidifiers

&= nbsp;

&n= bsp; Bubble Humidifier: gas conducted below surface of water, bubbles back to top and eventually to patient. Generally not heated. Cheap and popular for low flow devices.

Passover humidifier: gas passes over water surface and collects humidity. Can be heated.= Used with mechanical ventilators.<= o:p>

Wick humidifier: contains an absorbent sponge or paper which absorbs water, gas passes by wick and picks up humidity. Can be heated. Used with mechanical ventilators.<= o:p>

Condenser humidifier: AKA heat and moisture exchanger (HME) and artificial nose (AN). Must be placed so both inspiratory gas and expiratory gas passes through humidifier. Contains hygro= scopic particles which absorb and release water. Good for short-term use with mecha= nical ventilators. Not the greatest humidifier for long-term use or with patients who have excessive secretions= .

2. Diffuser in humidifier break bubbles into smaller bubbles so more surface area available for humidity collection.

3. = Factors which affect the amount of humidity delivered:

&= nbsp; &nbs= p; heater setting

&= nbsp; &nbs= p; gas flow rate

&= nbsp; &nbs= p; room temperature

&= nbsp; &nbs= p; length of delivery tubing

&= nbsp; &nbs= p; water level in jar or reservoir

4. Condenser humidi= fier must be placed so both inspiratory gas and expiratory gas passes through humidifier.

5. Humidity therapy important because respiratory tract is moist membrane with moist mucus responsible for removing infectious materials.

6. = Water in air exists as molecular(humidity) or particulate(aerosol) water.

7. = Molecular water (humidity) exerts a partial pressure and is invisible. Water in vapor= state.

8. Particulate water (aerosol) is water suspended in gas. Usually water molecules clumped together. Is visible and does not exert a pa= rtial pressure.

9. = Humidity measured as:

&= nbsp; &nbs= p; absolute humidity: actual water content of gas, measur= ed in mg/L

relative= humidity: compares ab= solute humidity to capacity of gas at certain temperature, measured as a percent

partial<= span style=3D'font-size:12.0pt;mso-bidi-font-size:10.0pt'> pressure: water vapor pressure, measured as mm Hg

10. Humi= dity capacity at 37^o =3D 43.9 mg/L, capacity at 21^o =3D 18= .4 mg/L

11. Relat= ive humidity =3D absolut= e water content of a gas

&= nbsp; &nbs= p; &= nbsp; &nbs= p; capacity of gas at that temperature<= /p>

12. Relative Body Humidity- comparing the water content of a gas to the capacity of a gas to hold water= at the patient’s body temperature.

13. Dew p= oint- temperature at which a gas becomes saturated with its contained water vapor= .

14. As the temperature of a gas increases, its ability to hold water also increases. Conversely, as the temperature of = a gas decreases, its ability to hold water also decreases.

15. Condensation forms when the temperature of a gas drops below the dew point and the gas can not hold all= the water at that temperature.

16. Adver= se effects of condensation in patient’s tubin= g:

1) decreased total flow

2) increased resistance to breathing

3) back pressure on air entrainment system leading to increased FiO₂

4) water collecting on O<= sub>2 analyzer probe

5) accidentally dump wate= r down patient’s ET tube or trach tube

6) inaccurate airway pres= sure readings

7) bacterial growth<= /o:p>

17. Gas s= hould have relative humidity of 100% when it reaches the lungs<= /p>

18. Anatomic structures responsi= ble for humidifying inspiratory gases: nose( most important), pharynx, trachea

19. Humidity deficit- most inspiratory gas is not at 100% relative body humidity or approximately 43.8 mg/L when it enters respiratory tract.&nbs= p; The amount of water that needs to be added to bring the gas to 100% relative body humidity is the humidity deficit.

20. Prima= ry humidity deficit- deficit to bring humidity from wall outlet to room humidi= ty.

&= nbsp; Secondary humidity deficit- deficit to bring from room humidi= ty to body humidity.

21. Water= lost by pulmonary tree in 24 hours =3D 200-250 ml

22. Water= loss by pulmonary tree increased by: increased ventilation, fever, dry air<= /o:p>

23. Adver= se effects of high humidity deficit-

dry secretions, mucus plu= gging, atelectasis, pneumonia, altered cilia function, tissue breakdown, increased mucus production, increased pressures on mechanical ventilator, airway irritability, increased work of breathing

24. Intubated or patients who ha= ve tracheostomies require added humidity or aerosol beca= use the body’s natural humidifiers are bypassed.

25. Factors affecting the effici= ency of a humidifier

1) temperature, 2) time of contact between gas and water, 3) surface area available for contact

11/11