Ventilator Skills Station What is a mechanical ventilator?

Ventilator Skills Station
What is a mechanical ventilator?
Mechanical ventilators are used to manage patients with respiratory insufficiency or respiratory
failure. These patients have an increased risk of healthcare-associated pneumonia because of the
presence of an artificial airway and the mechanical ventilation system itself. The artificial airway is
associated with increased opportunity for aspiration of bacteria colonizing the oropharynx and
gastrointestinal tract, because it bypasses the normal filtering defense mechanism functions of the
upper airway. Ventilation with a mask has been associated with reduced risk of pneumonia. For
infection prevention purposes, noninvasive ventilation is preferred in patients in whom acute
respiratory failure can be effectively managed by its use (e.g., exacerbated chronic obstructive
pulmonary disorder).
What are the parts of the mechanical ventilation system used with the ventilator?
Mechanical ventilators themselves are not usually sources of hospital-acquired infections, and the
internal circuits are not routinely disinfected or sterilized. Disposable items and fluids used for
ventilator operation are potential sources of infection.
Ventilator circuits
Ventilator circuits the ventilator tubing and, in some cases, the filter, exhalation valve, and
humidifier, which are removed and replaced with sterile equipment. CDC guidelines recommend
changing circuits only when visibly soiled or mechanically malfunctioning. No maximum time
between changes has been recommended for use of ventilator circuits when nonaerosolgenerating humidifiers are used.
Change intervals of 7, 14, and 30 days and a change between patients has been shown to reduce—
at least marginally—the risk of VAP when compared with 48-hour circuit-change intervals.
According to the American Association for Respiratory Care evidenced-based practice guidelines:
ventilator circuits should not be changed routinely for infection prevention purposes. The available
evidence suggests no patient harm and considerable cost-savings associated with extended
ventilator circuit change intervals. The maximum duration of time that circuits can be used safely is
unknown.
Frequent circuit change intervals (approximately every 48 hours) have been identified as a risk
factor for increased VAP. In-line temperature sensors are a potential source for contamination if
not disinfected properly. An assumption is made that the circuit and humidifier are a closed
system and that if the system is interrupted or broken (i.e., the patient is disconnected), the circuit
and patient connector should be handled so as not to contaminate them.
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Contamination of the ventilator circuit tubing and humidification systems, as well as circuit
change, has been implicated in VAP.
Tubing can rapidly become contaminated from the patient’s secretions, usually with bacteria
that originate from oropharynx or gastrointestinal tract.
Condensate that forms in the inspiratory line of the ventilator circuit can become
contaminated from patient secretions. Contaminated condensate (that collects in the
ventilator circuit) may spill into the patient’s tracheobronchial tree or into a nebulizer
reservoir. This can occur during a procedure where the tubing is moved (e.g., suctioning,
repositioning, changing ventilator circuits, or moving the patient) and may increase the risk of
infection.
Effluent from the ventilator circuit may contain microorganisms that can contaminate the
environment, increasing risk of transmission. Contaminants from the medical gas source (e.g.,
debris and condensed water in compressed air lines) may pass through the ventilator into the
patient’s airway.
Bacterial Filters
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High-efficiency bacterial filters in the breathing circuit, on both the inspiratory and expiratory
limbs of the ventilator circuit, should be used.
Filters should be used on the inspiratory limb to eliminate inspired gas contamination and,
theoretically, to reduce retrograde contamination of the ventilator. However, there is no
substantiated decrease in pneumonia rates with inspiratory-limb filtration. Filters may change
the operating characteristics of the ventilator by impeding high gas flows.
Bacterial filters should not be placed on the inspiratory limb between the humidifier and the
patient.
Filters and water traps should be used on the expiratory limb to help prevent crosscontamination.
Heat Moisture Exchangers
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One approach used to heat and humidity inspired gas and reduce condensate formation is the
HME, which provides passive humidification. This device is placed between the ventilator
circuit and the patient’s airway. An HME absorbs the humidity and heat from a patient’s
exhaled air and stores that heat and moisture.
Upon inhalation, the cold, dry gas from the ventilator passes through the HME picking up
the heat and moisture carrying it back to the patient. HMEs designed to act as bacterial
filters have not been proven to reduce VAP significantly over other less-expensive devices.
HMEs can increase mechanical dead space and resistance to breathing, and may provide less
humidity than active systems, resulting in thick, plugging secretions in some patients. To be
effective, more than 70% of the gas entering the airway must be exhaled through the HME;
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when leaks occur (e.g., bronchopulmonary fistulas or with cuffless endotracheal tubes), active
humidification systems are more effective. The CDC does not indicate preferential use of HMEs
over heated humidifiers to prevent healthcare-associated pneumonia.
The HME should be changed if there is gross contamination or mechanical dysfunction. There
are no guidelines regarding the length of time an HME may be used before changing. Resistive
changes often occur in the first several hours of use and do not appear to increase during
subsequent days of use, unless the device is grossly contaminated with secretions. Extended
use has not been associated with increase in VAP or problems with secretions.
A heat moisture exchanger (HME).
Routine ventilator care
Unfortunately, pneumonia in the ventilated patient (especially increased incidence or
outbreaks) often results in an automatic assumption that the ventilator itself is an associated
factor. Rarely is the equipment (e.g., ventilator) an associated factor, but it is prudent to have
standardized approaches to ventilator care and disinfection. The following points should be
considered in policy development and patient care activities:
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Use a heat moisture exchanger (HME) for the first 4 days of ventilation. HMEs are
discussed at length later in this document.
Change ventilator circuits every 7-14 days unless visibly soiled or malfunctioning.
Use sterile water to fill humidifiers. Tap water or distilled water can harbor organisms
such as Legionella spp. or Burkholderia cepacia.
Use clean gloves to drain condensate and wash or sanitize hands after removal of
gloves. This is an important issue since healthcare workers’ hands can spread
microorganisms from the condensate.
Drain condensate regularly. Do not allow it to flow toward the patient. Accumulated
condensate provides a moist environment that allows bacteria to thrive.
Use clean gloves when suctioning patients with closed or open system catheters.
Wash hands or use alcohol-based hand rubs after contact with any part of the
ventilator. Keyboard, knobs, dials, etc., are all considered to be contaminated
equipment and capable of being involved in organism transmission.
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Oral suction catheters should be stored in nonsealed paper or plastic bags when not in
use. This prevents accidental contamination if the item drops to the floor.
Oral care should be a standard patient care activity as a means of reducing oral flora and
the flora in oral secretions.
Do not store the oral suction where it can become contaminated or contaminate clean
supplies.
Do not lay the oral suctions on the ventilator or on the patient’s bed.
If the patient becomes disconnected from the ventilator, try to make sure the adaptor
does not become contaminated by falling to the floor. If contamination does occur,
contact the Respiratory Therapist immediately for assistance.
What is the proper procedure for emptying condensate from ventilator tubing?
The condensate in the circuits is a potential hazard to the patient if the fluid is accidentally
drained toward the patient. This provides a lavage of fluid with a potentially high bacterial load
in a warm, moist fluid environment.
Condensate that collects in the tubing of a mechanical ventilator should be periodically drained
away from the patient. Spillage can be minimized by the use of water traps carefully placed in the
inspiratory and expiratory limb of the ventilator circuits to allow gravity to drain condensate on a
continuous basis. Condensate should be treated as contaminated waste and disposed of properly
through the standard hospital waste stream.
When draining the condensate, the foremost objective is to prevent contamination. The
following steps can be used as a guide for good practice when draining the condensate from
the circuit:
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Cleanse hands before beginning the procedure
Put on clean gloves
Open the ventilator circuit carefully and try to avoid spillage or drainage of condensate
toward the patient
Drain the accumulated fluid into a collection container or dispose onto a clean towel or
absorbent pad. The towel should be placed immediately in the soiled linen container. If an
absorbent pad is used, it should be placed in the general trash unless visible blood is
present. If visible blood is present, the pad should go in the regulated waste container if the
quantity is sufficient to meet regulated waste disposal criteria.
Do not empty the fluid into the trash can. This can result in contamination of the
ventilator tubing and/or splashing onto environmental surfaces or healthcare worker
clothing.
Carefully reconnect the ventilator tubing to avoid contamination.
Remove gloves and dispose in regular trash.
Cleanse hands.
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An essential point of care when dealing with a ventilator is insuring that the ventilator circuits
do not become contaminated. This tubing should never be allowed to touch surfaces such as
patient bedding. If contamination occurs, the respiratory therapist should be immediately
notified.
Cleaning and Disinfection of Respiratory Care Devices
Proper cleaning and sterilization or high-level disinfection of reusable equipment is important to
reduce infection.
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Respiratory care devices have been classified as semicritical because they come into contact
with mucous membranes but do not ordinarily penetrate body surfaces. All equipment should
be thoroughly cleaned before sterilization or high-level disinfection. There is no evidence that
low-level contamination of a respiratory therapy device before patient use, such as occurs
after high-level disinfection of the device, presents greater risk than sterile equipment.
If equipment cannot tolerate sterilization by steam autoclave or ethylene oxide, high-level
disinfection can be performed. For example, disinfection can be achieved by pasteurization at
76°C for 30 minutes using a liquid chemical disinfectant approved by the Environmental
Protection Agency as a sterilant/disinfectant. During the pasteurization process, respiratory
equipment must be washed with a detergent and then placed in a specialized machine. The
machine is filled with hot water at approximately 70°C, and the equipment is submerged for
approximately 30 minutes (using manufacturer guidelines). This method is ideal for most
respiratory equipment because it is hot enough to kill the organisms, but not hot enough to
melt the equipment (because much of the equipment is made of plastic). Only sterile water
should be used if a device must be rinsed after it has been disinfected; tap water or locally
prepared distilled water may harbor microorganisms that can cause pneumonia. The number
of times the equipment should be rinsed after chemical disinfection is specified by the
disinfectant manufacturer.
Equipment and devices that are manufactured “for single use only” should not be reprocessed
unless data show that reprocessing poses no threat to the patient, is cost-effective, and does
not change the structural integrity and function of the device. Items such as pulse oximeter
sensors, stethoscopes, percussors, and other equipment that comes in contact with patients or
caregivers are often overlooked as sources of contamination and should be disinfected
between patients.
What is pneumonia?
Pneumonia is defined as a disease of the lungs caused by infection with microorganisms, and is
characterized by the accumulation of neutrophils in the bronchioles, alveoli and interstitium. A
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clinical definition of pneumonia requires that a new or worsening pulmonary infiltrate be
present along with an elevated white blood count and fever. Quality and quantity of sputum
production are also important clinical indicators. From an NHSN surveillance perspective, there
are 3 specific types of pneumonia: clinically defined pneumonia (PNU1), pneumonia with
specific laboratory findings (PNU2), and pneumonia in immunocompromised patients (PNU3).
General comments regarding pneumonia and NHSN surveillance
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Physician diagnosis of pneumonia alone is not an acceptable criterion for health care–
associated pneumonia.
Although specific criteria are included for infants and children, pediatric patients may meet
any of the other pneumonia specific site criteria.
Ventilator-associated pneumonia (ie, pneumonia in persons who had a device to assist or
control respiration continuously through a tracheostomy or by endotracheal intubation
within the 48-hour period before the onset of infection, inclusive of the weaning period)
should be so designated when reporting data.
When assessing a patient for presence of pneumonia, it is important to distinguish between
changes in clinical status due to other conditions such as myocardial infarction, pulmonary
embolism, respiratory distress syndrome, atelectasis, malignancy, chronic obstructive
pulmonary disease, hyaline membrane disease, bronchopulmonary dysplasia, etc. Also, care
must be taken when assessing intubated patients to distinguish between tracheal
colonization, upper respiratory tract infections (eg, tracheobronchitis), and early onset
pneumonia. Finally, it should be recognized that it may be difficult to determine health
care– associated pneumonia in the elderly, infants, and immunocompromised patients
because such conditions may mask typical signs or symptoms associated with pneumonia.
Alternate specific criteria for the elderly, infants and immunocompromised patients have
been included in this definition of health care–associated pneumonia.
Health care–associated pneumonia can be characterized by its onset: early or late. Early
onset pneumonia occurs during the first 4 days of hospitalization and is often caused by
Moraxella catarrhalis, H influenzae, and S pneumoniae. Causative agents of late onset
pneumonia are frequently gram negative bacilli or S aureus, including methicillin-resistant S
aureus. Viruses (eg, influenza A and B or respiratory syncytial virus) can cause early and late
onset nosocomial pneumonia, whereas yeasts, fungi, legionellae, and Pneumocystis carinii
are usually pathogens of late onset pneumonia.
Pneumonia due to gross aspiration (for example, in the setting of intubation in the
emergency room or operating room) is considered health care associated if it meets any
specific criteria and was not clearly present or incubating at the time of admission to the
hospital.
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Multiple episodes of health care–associated pneumonia may occur in critically ill patients
with lengthy hospital stays. When determining whether to report multiple episodes of
health care–associated pneumonia in a single patient, look for evidence of resolution of the
initial infection. The addition of or change in pathogen alone is not indicative of a new
episode of pneumonia. The combination of new signs and symptoms and radiographic
evidence or other diagnostic testing is required.
Positive Gram stain for bacteria and positive KOH (potassium hydroxide) mount for elastin
fibers and/or fungal hyphae from appropriately collected sputum specimens are important
clues that point toward the etiology of the infection. However, sputum samples are
frequently contaminated with airway colonizers and therefore must be interpreted
cautiously. In particular, Candida is commonly seen on stain, but infrequently causes
healthcare-associated pneumonia.
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