Humidity & Bland Aerosol Therapy PDF

Lesson 3 1 2  Absolute Humidity  Relative Humidity  The amount of water in a given volume of gas  A ratio between the amount of...

Lesson 3 1 2  Absolute Humidity  Relative Humidity  The amount of water in a given volume of gas  A ratio between the amount of water in a given  Expressed in mg/L volume of gas (content) and the amount it is capable of holding at that temperature (capacity)  Expressed as a percent and measured with a hygrometer  RH = (Absolute Humidity/Capacity) x 100 3 4  Involves adding water vapor and sometimes  Objective heat to the inspired gas  Compensate for water loss that occurs when dry  Water in a gaseous state gas is delivered or when the upper airway is  Also called molecular water or invisible bypassed in order to maintain normal physiologic moisture conditions in the lower airways 5 6 1   Nose  Warms, humidifies and filters inspired air  Pharynx, trachea and bronchial tree  Also warm and humidifies inspired air  As inspired gas moves into the lung it eventually achieves BTPS (100% RH at 37 degrees C)  Occurs at about 5 cm below carina (isothermic saturation boundary) 7 8  Above the ISB, temperature and humidity  Factors shifting ISB deeper into the lungs decrease during inspiration and increase  Breathing through the mouth during expiration  Breathing cold, dry air  Below the ISB, temperature and RH remain  When upper airway is bypassed constant  When minute ventilation is higher than normal  When a distal shift in the ISB compromises the body’s normal heat and humidification, humidity therapy may be indicated 9 10  When inspired air is fully saturated (100%) at  Relative humidity at body temperature body temperature  Expressed as a percentage  It holds 44 mg/L of water  Body Humidity = (Absolute Humidity / 44 mg/L) x 100  Exerts a water vapor pressure of 47 mmHg 11 12 2  Actual moisture deficit between the inspired air and the needs of the body  May be expressed in mg/L or as a %  Humidity Deficit = 44 mg/L - absolute humidity  When expressed as a %  (Humidity deficit / 44 mg/L) x 100 13 14  Primary  Medical gases at flows >4 lpm causes heat  Humidify dry medical gases and water loss to upper airway  Overcoming humidity deficit created when upper  Decreased ciliary motility airway is bypassed  Airway irritation  Secondary  Increased mucus production that can become  Managing hypothermia (must heat) thick and inspissated  Treating bronchospasm caused by cold air (must heat) 15 16  If upper airway is bypassed, the hazard of breathing dry gas is even greater  Breathing dry gas through and ET tube can cause damage to tracheal epithelium within minutes 17 18 3  Management of hypothermia  Heating and humidifying gases is one technique to raise core temperature  Temperatures over 40 degrees Celsius will burn the airway  Alleviation of bronchospasm caused by cold air 19 20  Humidifiers add molecular water to a gas  Most important factor affecting humidifier  Physical principles affecting humidifier performance function  If enough heat can be added, the effects of a small  Temperature surface area or short contact time can usually be  Surface area overcome  Contact time  The greater the temperature the more water vapor it can hold  Heated humidifiers always outperform non- heated humidifiers 21 22  The greater the surface area of contact between water and gas, the more opportunity for evaporation to occur 23 24 4  The longer the gas is in contact with the  Bubble humidifiers water, the greater the humidification  Passover humidifiers  Low flows provide more contact time, therefore  Simple provide more humidity than high flows  Wick  Membrane  Heat Moisture Exchangers 25 26  Breaks an underwater gas stream into small bubbles  Commonly used with oronasal O2 delivery systems  Provides about 25% body humidity  Becomes less effective as flow increases  limited effectiveness at flows > 10 lpm 27 28  Don’t heat – condensation obstructs tubing  Direct gas over a water surface  Incorporate a simple pressure relief valve  Can deliver 100% body humidity (pop-off) that release pressure above 2 psi  3 types  Simple passover  Wick  Membrane-type 29 30 5   Wick is placed upright in a water reservoir and surrounded by a heating element.  As gas enters the chamber, it flows around the wick, picking up moisture and leaving the chamber fully saturated 31 32  Separates water from the gas stream by  Maintain saturation at high flows means of a hydrophobic membrane.  Add little or no resistance to spontaneous  Water vapor molecules can easily pass breathing circuits through this membrane, but liquid cannot 33 34  Also known as artificial nose  Captures exhaled heat and moisture and uses it to heat and humidify the next inspiration  Should be used for short term humidification ( 30 mg/L of water vapor (can be accomplished with temperature set 35°C ± 2°C. 43 44  Liquid particles suspended in a gas 45 46  Sterile water  Improve the mobilization of respiratory  Hypotonic saline - 0.9% tonicity to prevent or relieve bronchospasm or inflammatory response  Hydrate airways of tracheostomy patient  Induce cough for sputum collection 47 48 8   Large volume jet nebulizer  Impeller nebulizer (spinning disk or room humidifier)  Ultrasonic nebulizer 49 50  Most common  Generates aerosol by gas passing at high velocity through a small “jet” orifice  Utilizes Bernoulli principle entrain room air and to draw water up the capillary tube into the gas stream to produce aerosol  Length, kinks, or water in tubing will decrease air entrainment and increase FiO2 51 52  If flows provided are not high enough, connect 2 or more nebulizers together with a “wye” connector 53 54 9  Disk rotates rapidly, drawing water up from the reservoir and throwing it through a slotted baffle, reducing the size of the particles  Popular for home use but does not produce clinically adequate aerosol output  Difficult to keep clean  High source of contamination 55 56  Piezoelectric transducer in couplant chamber  Frequency of the transducer is preset by the of the unit is electrically charged and factory and cannot be changed produced high frequency vibrations  Frequency controls the particle size  Vibrations break up the medications in the  Amplitude determines the volume of the cup into small particles, which are delivered aerosol output by altering the transducers to the patient vibrational energy 57 58  Has the highest output range without heating  Aerosol mask  90% of aerosol particles produced fall within  Face tent the 0.5 to 3 micron range  Tracheostomy tube (T-bar, Briggs adapter)  Tracheostomy mask  Mist tents 59 60 10  Short-term application of hypertonic saline  Cross-contamination and infection (3%-10%) to assist in mobilizing secretions  Environmental safety (for for sampling immunosuppressed and TB patients)  Need to use an aerosol device that delivers  Inadequate aerosol output high-density mists  The increase volume in surface fluid and  Inadequate input flow, siphon tube obstruction, irritation to airway produces a cough reflex jet orifice misalignment  Box 39-6 (page 835)  USN - check electric supply, gas flow through device, amplitude setting, couplant chamber for proper fill level, dirt or debris 61 62  Overhydration  Bronchospasm  Risk highest in infants and small children  If this occurs, stop therapy, give O2, administer  Risk also high in patients with preexisting fluid or bronchodilator electrolyte imbalances  If physician wants to continue with aerosol  Normal daily water gain for an adult is 200 ml/day treatment, it is appropriate to give because aerosol compensates for insensible water bronchodilators at specific intervals loss  Swelling of secretions 63 64 11