 |
|
|
|
|
 |
Page 1Indications, contraindications & hazards common to aerosolizing any medication Because we use SVN (small volume nebulizer) to deliver specific drugs, most of the indications, contraindications and hazards are associated with the drug we are using. To deliver aerosolized drugs to the patient one uses specialized nebulizers. The nebulizer one selects to do this job will be determined by the drug to be administered and exactly where in the lung we need to deliver the dose. · Volume of the drugs varies from ˝ ml (for most drugs) to 300 mL for the occasional SPAG dosing. · Time the patient must be under the drug: most drug delivery will take 10-15 minutes [average is 5 minute/cc of drug] but some drugs take 20-30 minutes and one takes 18 hours to administer (the one with 300 ml)
The drugs we will use
· Most patients getting inhaled drugs will have bronchospasm, wheezing and coughing with or without increased secretions. For this we need bronchodilators to decrease the airway resistance. A steroid inhaler helps prevent wheezing, but it's of little immediate use. · Many patients will have increased mucus that is too thick for the patient to cough up effectively. For this we need mucolytics to thin out the secretions · Other patients will have swollen airways. For this we need anti-inflammation drugs to decrease the airway resistance · Many patients will have infections that can be treated by inhaled drugs. Some of these drugs are delivered by large volume nebulizers some antibiotics and other anti-microbial agents can be delivered by SVN
Drugs used in SVN
See Our Bronchodilators Page For More Information..
The bronchodilators we use the most
in RC are in the Beta II adrenergic class. These drugs
trigger bronchodilation. Beta II drug effects and side effects are related to the specific receptor to which the drug attaches. There are three we will discuss. The receptors are located on various organs and if the correct drug lands on them, various events will occur. Examples are: · Albuterol Sulfate: (Ventolin, Proventil) beta II · Xopenex (levalbuterol) Beta II · Metaproterenol (Alupent) beta I and II · Pirbuterol (Maxair MDI) · Terbutaline (Breathaire) · Salmeterol (Serevent)
Cholinergic antagonists We augment Beta II drugs with a different class of bronchodilators called cholinergic antagonists. These drugs work by blocking bronchospasm. Examples are: · Atrovent (ipratropium bromide) · Atropine (older drug used less often for asthma)
Mucolytics Agents that are used to break up mucus. These could be sterile water or sterile saline or drugs like mucomyst.
Agents that are used to decrease the swelling that accompanies infection or allergic reaction. Inhaled steroids are the most common type of anti-inflammatory used in asthma and in COPD. These are usually not administered by SVN but by MDI · Vanceril MDI · Beclovent MDI (beclomethasone) · Flovent MDI, (fluticasone) · Azacort MDI · Aerobid MDI
Anti-infective agents Agents such as antibiotics Bronchodilators
* Drugs that cannot be mixed with other starred drugs because they are all Beta II Hazard Key: N & V: nausea & vomiting due to Beta II stimulation of digestive tract smooth muscles T: tremors and shakes due to central nervous system and increased blood flow to skeletal muscle in preparation for fight or flight N: nervousness due CNS as well as noticing the shakiness and other side effects HR: increased HR & cardiac arrhythmia's [most dangerous Beta I] B: bronchospasm or cough [note that Atrovent can cause cough before it treats cough & wheeze] R: rebound. Rapid tolerance leads to decrease ability of the body to react to the drug so that the patient's condition comes back and sometimes worsens.
While most antibiotics cannot be given by inhalation there is a short list of antibiotics that can be given: Form of inhaled Tobramycin called Tobi which is indicated for the treatment of pseudomonas aeruginosa specifically in patients with Cystic Fibrosis There are other antimicrobial agents · Pentamidine to treat and maintain AIDS patients who have PCP pneumonia (caused by a parasite) · Ribavirin to treat kids under 2 years-old who are diagnosed with RSV pneumonia (caused by a virus) Page 2Method of operation of small volume nebulizers SVN
Specific types of SVN The pneumatic SVN: most of the time this is the one the RCP uses. It delivers particles to the central airways and is the one used to deliver bronchodilators & mucolytics to the airways. How does the pneumatic nebulizer work?  · Gas moves down the driveline to the jet where the capillary tube meets it. The medication is drawn up the tube and the particles are shattered against the baffle · Air is entrained from the end of the reservoir hose. The longer the reservoir hose, the less room air is entrained so Fi02 increases, as well as more medication is made available to the lung · As long as the gas is flowing, the medication is aerosolized · The average dose that the medication cup can hold is between 3-5 cc at a flow rate of 6-8 lpm. It takes about 5 minutes to nebulizer each 1 cc of drug · Due to evaporation of the water in the cup, the drug concentration tends to rise toward the end of the treatment o Gas source can be: § 50 psig of 02 § compressed air [21%] § At home one may use the smaller air compressors created for SVN use.
There is a one-way valve on the mouthpiece for exhalation. There is a 'lip' on the mouthpiece to prevent drool from entering and contaminating the nebulizer cup. Because the patient gets so much more medication with the BA SVN, there is a feeling that we might need to decrease the amount of saline given, even to decrease the amount of active bronchodilator.
The hand held ultrasonic nebulizer: There has been an effort in some circles to replace the standard SVN for home use with an ultrasonic unit. These would be used for bronchodilator delivery as well as mucolytics. However the ultrasonic technology is expensive and they may have trouble breaking into the market. The advantage of the hand-held ultrasonic is that because it doesn't run off the gas flow, there is no spray of medication going all over the place. The nebulizer holds the mist until the patient inhales. Only then does the medication move along the tube. The result of this is that homecare patients report such effective treatments that some have had to cut back on their medication dosages to get the same results. The hand-held ultrasonic nebulizers have adaptors for cigarette lighters in cars. Servo 300 ventilator uses an ultrasonic nebulizer to deliver medication because there is no increase in Raw down the narrow pediatric tubes as seen with the increased flow rates of the regular SVN. There is no inadvertent increase in volume & pressures.
The Aerogen TM SVN
The Aerogen generator consists of an electrically powered vibrational element with dome-shaped holes that allows the medication to be suspended above the element. This generator is dime-shaped and doesn't create as much heat as an ultrasonic nebulizer The SPAG unit for Ribavirin delivery *Also See SPAG
Strictly speaking, the SPAG unit could be classified as a large volume nebulizer, because the device holds 300 ml of drug [Ribavirin] and a treatment lasts 18 hours. We will classify it as a SVN only because its function is to deliver drugs. SPAG stands for small particle aerosol generator. The Collision generator was a pneumatic aerosol generator developed by the USA military to deliver drugs to the alveoli. Later, the FDA Ok'd its use with small children and infants to deliver Ribavirin for RSV pneumonia & bronchiolitis. The operative part is the Collision generator, a triple capillary tube pneumatic nebulizer with metal parts. The metal jet runs off 25 psig. This triple capillary system reduces the particles, and then the medication is carried to a drying chamber where the excess water is dried off. The remaining particles become invisible to the naked eye [about 1.3 microns.] The SPAG unit has two flow meters. One to go to the triple capillary jet and the other goes to go to the drying chamber. Both must be set. The aerosol hose is sent from the drying chamber to a tot hut or an infant hood. Although the size of the enclosure will dilute the medication, it could be put into a croup tent. The use of a mask is a waste of time unless the RCP wants to hold it to the child's face for hours because children under 2 years old do not allow masks [or anything else] on their faces without a fight. There may need to be an additional flow 02 flow coming to the patient from a heated humidifier or cool aerosol generator if the 15 lpm is not enough flow to get to the patient. Fi02 is controlled by an 02 blender set upstream from the SPAG. The total flow going to the patient is 15 lpm because the triple capillary jets will not allow a faster flow than about 6-10 lpm. The drying chamber's flow meter is increased until the flow to the patient is 15 lpm. Circulaire aerosol generator
The Circulaire TM SVN is a standard SVN with a reservoir bag that replaces the flex hose reservoir. There is also a one-way valve between the patient and the nebulizer. This one-way valve allows aerosol to go to the patient but more importantly it baffles the particles once more, making them smaller. Because the reservoir bag contains the drug, and conserves it, drugs may be delivered in dilutants of only 1.5 mL instead of 3 mL. One study of 64 patients showed that there was a significant increase in the PEFR of persons who used this SVN compared to the traditional one. This increase in PEFR implies a decrease in wheezing. There was no increase in nausea and vomiting. The persons who received their Albuterol via the Circulaire TM had decreases in both respiratory rates and in heart rates.
Heart TM nebulizer The Heart TM nebulizer is an adaptation of a pneumatic SVN in which the medicine cup holds a volume of about 240 cc instead of the traditional 6-8 mL. There is a smaller one that holds about 30 cc. These two devices are used to deliver continuous aerosol to persons [generally, kids or young adults with strong hearts] in status asthmaticus. The effects, both + and – of this TX, must be assessed and the patient returned to conventional TX as soon as the bronchospasm “breaks.” Generally, the only drug recommended by the AHA 2005 clinical guidelines for this extreme form of therapy is Albuterol. This same effect can be accomplished with a regular pneumatic SVN if an IV pump is attached to a line and bled into the nebulizer cup. These will deliver drugs over a long period of time.
This adaptation of a traditional SVN is used to deliver much smaller particles [1-2 microns] to the bronchioles and the alveoli. With the Respirgard II TM , the RCP can get particles of Pentamidine deep enough in the lung to treat PCP pneumonia which is associated with AIDS and other immune problems. This nebulizer has a bacteria filter at the exhalation port to protect the RCP from the patient's exhaled gases. [Both the patient's germs and toxic drugs are undesirable ] It has one-way valves at three places: · On the distal end of the 5-inch flex hose reservoir. This is used to keep the aerosol from leaving the circuit on exhalation. When the patient inhales he can pull in air but not exhale medication. · The other one-way valve is between the nebulizer and the patient. This acts to baffle the particles
·
There is a third one-way valve that faces the bacteria filter so
that the exhaled gas is sent to the bacteria filter
The PARI TM is a non-disposable, pneumatic SVN that can be autoclaved or sterilized by boiling, so it is a nebulizer created for the homecare market. It is used mainly to deliver an inhaled form of Tobramycin antibiotic [Tobi], which is the antibiotic of choice for patients with Pseudomonas Aeruginosa. Pseudomonas A is the most common infection spread by respiratory care equipment so it is a very common infection in children with cystic fibrosis [CF] because they are generally managed with routine SVN treatments all their lives. Administration of antibiotics such as Tobramycin by mouth (PO) is less than optimal in these patients who have poor absorption of their intestines so they must get long term IV or long-term inhaled treatments. The PARI TM nebulizer has its own mask or a mouthpiece. The mouthpiece has an exhalation port with a flap. This flap acts as a one-way valve that allows exhaled gases to exit the device.
Metered dose inhalers MDI Drugs are delivered to the patient in a spray from a pressurized canister. To find out if the canister is empty, the RCP should put it into water and see if it floats on top (empty) or sinks to the bottom. The aerosols from these devices are large at first but evaporate quickly. The MDI contains not only active medication but also a pressurized Freon-based propellant that pushes the drug once the valve stem opens the canister to the atmosphere. There is concern about the role of these Freon molecules to the ozone layer and there is a government push to replace Freon with safer propellant. However, MDI's only add .4%-.5% to the annual chlorofluorocarbons emissions in the world Excessive use of the MDI (more than about 8)
As particles move down a tube, every time the tube bends, the heavier particles impact on the wall and go no further while the smaller ones keep going. This is called rainout. So the size of particles generated by an aerosol is important to the good function of the machine. And the selection of a particular aerosol generator is based on the particle sizes the RCP will need for the type of drugs they need to deliver. The aerosol particle diameters required for deposition in the various parts of the lung. · Greater than 5 microns rains out in the nose · 5-10 microns enter the lower airway if the patient is mouth breathing · 1-5 microns enter the periphery of the lung · Particles of less than 1 micron may not impact on the walls of the airways, they are too light for gravity and may just get exhaled out.
The average MMAD of the hand-held SVN is about 3 microns but it varies with the frequency set by the manufacturer. The operator cannot change these frequencies, because they are set by the manufacturers, based on FCC regulations. Comparisons of the SVN used
Reservoirs, finger ports, and spacers in the delivery of drugs Finger ports: multiple studies have shown that intermittent activation of the nebulizer only on inspiration will result in greater amounts of drug delivered to the patient. The use of the finger port results in a slightly longer treatment and poorer patient compliance. Spacers: when spacers are added to the MDI as a reservoir, the patient whose technique is faulty will do better and get more medication. Use of Spacers will result in less oral deposition which is good for steroid MDI's. Spacers with mask are recommended for infants and small children & for the confused elderly patients.
The advantage of the mouthpiece is that there is more deposition of gas into the lungs compared to the mask. In most cases we prefer to use the mouthpiece but---- Saying this I must add that: · The mask will result in a more diffuse spread of gas that may be less irritating to persons with strong gag reflexes. If the patient gags easily, aim the mouthpiece a slightly different angle--- or change to a mask · If the RCP is using relaxation techniques, the mask works better · If the patient is confused or a child who cannot cooperate, the mask works better
SPAG:
There are concerns about the
teratogenic side effects of Ribavirin in small mammals and there
have been attempts to shield the caretakers form the drug.
But it must be added that the patient must take this drug for 18 hours at a time and studies have shown the drug may not be in the blood stream until after 12 hours of constant exposure. The RCP is rarely in the room for more than 20-30 minutes at a time. This may be more of a problem for a pregnant mother or nurse than the RCP. As far as mixing Ribavirin, many hospitals have the drug mixed in the pharmacy because a laminar flow table is used to keep the drug sterile. Under these circumstances, the RCP has limited exposure. However pregnant pharmacy staff needs to stay away.
· s/s of bronchospasm (indications) o History of COPD, emphysema, asthma or chronic bronchitis o Increased use of accessory muscles o Wheezing, prolonged expiratory time (Te) or diminished breath sounds o I:E ratio effected by prolonged Te o Pulmonary function tests denoting slowed expiratory flow rates · s/s of air trapping (indications) o History of COPD, emphysema, asthma or chronic bronchitis o Increased AP diameter on X-ray or exam o Pulmonary function tests o Increased resonance on percussion o Diminished breath sounds · s/s of cardiac instability (hazards) o Check baseline heart rate o Check EKG report, looking for "tachy" arrhythmia (HR over 120 bpm are suspect) o History of cardiac arrhythmia, c/o chest pain, angina, history of Congestive heart failure o Look at RCP charting to see the effects of the last treatment on the heart rate · s/s of blurred vision? o problem with Atrovent · s/s of gastric tract irritation or other side effects (hazards/side effects) o Look at RCP charting to follow the effect of the last treatments: did the patient vomit, c/o nausea? o Does the patient c/o stomach cramps Ideal volume and Ideal flow rate for the SVN
For most traditional SVN's, studies
have shown that the optimal volume of drug is starting with 5 cc
at the ideal flow rate |
