Vol. 15 •Issue 13 • Page 34
Welcome to My World
You Can Help Stop Ventilator Associated Pneumonias
As RTs, we read about ventilator-associated pneumonias (VAP) all the time, but I as an educator and practitioner have my doubts that we are really listening to those materials. I have the good fortune to stay in touch with various medical centers throughout the country and find myself alarmed at the rate at which nosocomial infections are developing.
Unfortunately, they are not limited to your garden variety anymore but have escalated into a host of medically resistant germs that defy our best attempts at eradication. The good news is that none of this need happen if we remain diligent and practice good medicine.
Our printed guidelines for ventilator circuit changes and types of circuits to use are hopelessly outdated. What is clear is the reason we change circuits is to prevent nosocomial infections as a result of endotracheal intubation or tracheotomy and ventilator support.
Other continuing guidelines that seem to remain are the length and time an existing circuit is used, the type of humidification support the patient receives, and the general appearance of the circuit itself. While some may argue there are patients who are thermodynamically unsuitable for circuit changes, the experienced practitioner should be able to change a circuit completely in 15Ð20 seconds. This generally should not cause any harm to the patient; however, the practitioner must still remain aware of the stress placed on the intubated patient during this time.
Nosocomial bacterial pneumonias are, for the most part, difficult to diagnose. Criterions for this condition have remained fever, cough, purulent sputum, development of infiltrates, suggestive Gram’s stain and cultures of sputum, tracheal aspirate, pleural fluid or blood cultures.
Nosocomial pneumonias have been associated with high mortality rates, especially for patients on mechanical ventilation. Colonization occurs more rapidly in patients with coma, hypotension, acidosis, azotemia, alcoholism, DM, leukopenia, pulmonary disease, nasogastric or endotracheal tubes in place or in patients receiving antimicrobial agents.
LOOKING FOR ENTRY
Bacteria gain entry to the patient in a variety of ways. They can enter through the respirator tract via contaminated aerosol generating devices, contaminated water humidification devices, exposure to contaminated respiratory equipment, contact with colonized hands of a health care provider, inadequate pulmonary toilet and immobilization due to trauma or illness.
Bacteria may be carried in along with the endotracheal tube itself. Several studies indicate the risk of VAP increases approximately 1 percent each day of mechanical support. Bacteria that accumulate on the tube may become dislodged over time with repeated suctioning, ventilation flow or tube manipulation.
To reduce cross contamination, caregivers should use gentle suctioning, or something as simple as using asceptic technique if you use a standard 14 Fr catheter for nasotracheal or open tracheal suctioning. Of course, always use proper handwashing prior to and after gloving too.
Ventilators themselves do not generally pose a risk to the patient since most use a bacteria filter between the ventilator outlet and the patient inspiratory limb of the circuit. Many institutions use a non-heated wire circuit as the initial circuit the patient will encounter.
However, the choice of humidification options will determine bacteria growth rate. For example, if the simple circuit is used with a hygroscopic condenser humidifier (HME, artificial nose), the circuit will remain dry and bacteria free. These devices reflect the patient’s own native moisture and heat and conserve those elements. However, there are patients who should not be placed on a circuit that uses an HME. Those who have copious thick secretions, expired tidal volume of less than 70 percent of the delivered volume, low body temperatures, high spontaneous minute volumes (>10LPM) and high respiratory rates or those with bronchopleural fistulas or cuffless tubes should not be placed on an HME.
These patients will require a heated humidification source. This will increase the rainout in the tubes and provide a hospitable habitat for bacteria. Usually patients who will be on the ventilator for only a few hours (post-op) or a day or two will do well with this system.
If it is anticipated the patient will be on a ventilator for longer than 48 hours, a heated-wire circuit should be used with a heated humidification device (not an HME). If the heater is set properly and the relative humidity factor is properly set, condensation in the inspiratory limb should be well controlled.
However, dried secretions become a problem that can cause blockages in the ET tube or tracheostomy tube. Our standards of practice commonly show that heated-wire circuits are generally changed once a week or PRN. Several studies show that if they are properly maintained as I have previously stated, it may be acceptable to leave that circuit for the duration of the patient ventilatory support.
Would I recommend this? In a word, no! It is impossible to be that fastidious or painstaking about the circuits. Make no mistake, there will be condensation (rainout) and bacteria will flourish.
The aerosol delivery devices we use to deliver medication to our ventilated patients (as well as those in our regular floor practice) should be changed on a regular basis too. They should not be left with fluid in them (either left-over medication or sterile water used to rinse them) since this can become a breeding ground for bacteria.
Rinsing is fine as long as the device is properly dried and stored. To prevent infective agents from entering the patient via this route, it is advisable to change the SVNs every 48 hours or sooner PRN.
If we practice good technique, asceptic procedures, wash our hands, glove and wash again after degloving, keep our equipment clean, suction gently but completely, change the HME daily and PRN, be mindful of our humidification techniques and keep in mind the safety of our patients, we will not betray them by giving them something else to worry about, something like VAP. . ‘
Paul B. Olkin is the director of Clinical Education at Shenandoah University, Winchester, Va.