At some point in their careers, biomedical equipment technicians (BMETs) and clinical engineers are exposed to ventilators and other respiratory support equipment. Because they are complex, high-risk life-support devices that do not allow for error, many biomeds who prefer challenges enjoy working on this type of equipment. Less experienced technicians interested in working with mechanical ventilation systems must obtain additional training or take specific courses offered by independent training companies or manufacturers to acquire specific knowledge needed for this type of work.
“Ventilators need to function properly because if they don’t, the patient can stop breathing,” says Kerwin Sanger, training manager for Temecula, Calif-based South Pacific Biomedical Inc, a company that offers training programs for biomeds in ventilator servicing and repair. “With many other types of medical equipment, such as humidifiers and blood pressure monitors, if they fail you can get a bad diagnosis, but they won’t injure the patient. This is not the case with ventilators.”
Many biomeds working in both hospitals and for third-party service organizations need specialized training in how to service ventilators. They may know how to operate them and conduct self-tests, but they lack information on the basics of ventilation and specific nuances of the equipment.
The Basics of Mechanical Ventilation
A ventilator consists of a compressible air reservoir, air and oxygen supplies, a set of valves and tubes, and a disposable or reusable patient reservoir. The air reservoir is pneumatically compressed several times a minute to deliver oxygen to the patient. Ventilators are also equipped with monitoring and alarm systems for patient-related parameters (pressure, volume, and flow), and ventilator function (air leakage, power failure, mechanical failure). The patient circuit generally consists of three durable but lightweight plastic tubes, separated by function, involving inhaled air, patient pressure, and exhaled air.
The three different modes of ventilation—volume-, pressure-, or time-cycled—are classified based on how they control ventilator breath. In a volume-cycled modality, the ventilator delivers a preset volume of gas with each breath. As soon as the specified volume of breath is delivered, the positive pressure is terminated. In a pressure-cycled ventilator, once a preset pressure is reached within the ventilator, the breath is terminated. When a time-cycled ventilator is used, the termination of the breath occurs after a specified time period. Many manufacturers now offer machines that utilize some functions of each. Sanger stresses that biomedical technicians should be trained to understand each of these methods and how to verify the ventilator’s performance and accuracy while operating in each of these ventilation modes.
The choice of ventilation mode is typically based on the clinical situation, and in some cases the respiratory therapist’s preference. Because there are benefits to using one mode of ventilation over another, the choice of ventilator management is extremely important. Ventilator management is a multidisciplinary effort involving physicians, respiratory therapists, and nurses.
The types of ventilators used in the hospital setting can also be broken down in terms of the three populations they serve: adult, pediatric, and neonatal patients. In general, earlier types of ventilators used with adults and children were not suitable for neonates because of their need for a wide range of volumes and pressures. Today’s universal ventilators have solved that problem, since they are designed specifically to address the different requirements of adult, pediatric, and neonatal patients with a single instrument. Preset ranges for all relevant flow and volume parameters can be automatically adjusted using a patient-range button, allowing therapists to safely customize preferred treatment parameters.
“I prefer working on universal ventilators,” says Steve Schafer, director of biomedical services for Lewisville, Tex-based Biomedical Professionals LLC, a third-party organization that services medical equipment in five states. “The drawback is that the universal vents are a bit more challenging to work on since you’re dealing with flows less than 5 mL all the way up to a liter or a liter and a half.”
On the flip side, the benefit to the hospital is that there are fewer types of ventilators to service, resulting in fewer parts that have to be supplied and cost savings. Training biomedical technicians is also easier and less costly since they are all training on the same piece of equipment.
|Test lungs simulate an actual clinical situation.|
Most ventilators have built-in alarms that let respiratory therapists know if the ventilation parameters have exceeded what was originally established for a specific patient. For example, if a therapist wants to deliver 500 mL of flow, a tidal volume can be set that indicates if this amount is either exceeded or falls short. “A therapist can make it a tight alarm between 499 and 500, or wider, from 200 to 600,” Sanger says. “The manufacturers have developed this equipment so that there’s a wide range of alarm parameters, primarily because most ventilators service a wide range of patients.”
The alarm systems of newer ventilators use flashing lights in conjunction with audible alarm sounds, and in some situations rank alarm severity with different-colored lights. This indicates to busy nurses and respiratory therapists how serious the problem is for a specific ventilated patient. Some hospitals also have all of their ventilators connected to a central monitoring system, so that certain staff can be assigned to monitor the ventilators, and respiratory therapists do not have to be distracted from taking care of other patients.
Kelly Wright, CBET, RRT, a biomedical technician II at 300-bed Christus St Michael Health System in Texarkana, Tex, believes the interpretation of alarms and the correction of malfunctioning alarms is the most challenging aspect of working on ventilators. Since Wright worked as a respiratory therapist for a few years before becoming a biomed, he understands the confusion that therapists experience with ventilator alarms. “I work with the therapists to alleviate their fears that something is wrong with the ventilator by giving them the tools they need to troubleshoot problems,” Wright says.
Ventilator Testing Equipment
Because the failure of a mechanical ventilation system may result in death or serious injury, precautions must be taken to ensure that the equipment is extremely reliable. Fortunately, due to advances in technology, the devices that analyze ventilator performance are readily available and extremely accurate. Two different types of equipment are used for testing ventilators: a pneumatic analyzer, which measures the flow and pressure of gasses; and an artificial lung, which, when used with the pneumatic analyzer, verifies the performance and accuracy of the ventilation system under test.
Modern pneumatic analyzers can be portable battery-operated devices that typically test a variety of other medical devices such as anesthesia gas delivery machines, insufflators, and oxygen concentrators. Because most pneumatic analyzers are portable, hospital biomedical engineering departments often own this equipment. Specifically designed to measure tidal volumes, respiratory rates, patient circuit pressures, I:E ratios, and flow rates of air, oxygen, nitrous oxide, and a variety of other gasses and gas mixtures, the test equipment can generally be used in servicing all types of ventilators including neonatal and high-frequency machines.
Test lungs, also called training/test lungs, are essentially lung simulators capable of simulating an actual clinical situation, and can be adapted to meet the specific requirements of the individual ventilator. “In recent years, many advances and options in test lungs have become available, making servicing and simulation easier than ever,” says Mario Carvajal, president and CEO of South Pacific Biomedical. “Test lungs that were once not much more than a bag have now become sophisticated devices that include variable compliance, resistance, and leak features.”
PM is an important task in ensuring that ventilators are running properly. The ventilators found in most hospitals today range from requiring a minimal amount of PM to an extensive amount, meaning that many parts are replaced during the PM cycle. As Sanger points out, the Puritan-Bennett 7200 requires major parts replacement every 10,000 hours, while the Siemens/Maquet servo needs no replacement parts during its PM.
Since respiratory equipment is more complex than other forms of medical equipment, there is generally a shortage of qualified biomeds trained to work on ventilators. Many respiratory therapy departments and hospitals require that technicians be trained on specific ventilator models before conducting service on them. Third-party organizations that are responsible for a myriad of ventilation equipment service should also be trained on each model for which they provide service. Training programs that address the specific needs of each ventilator model typically run from 2 to 5 days in length and are offered through the manufacturers and independent training organizations.
Steve Schafer, director of biomedical services for Lewisville, Tex-based Biomedical Professionals LLC, is currently in the process of recruiting a biomed with this background and notes that it is a skill set that many individuals do not possess. “You can’t hire a relatively inexperienced BMET to handle these responsibilities,” he says. “Not only is it invasive, but it also relies on pneumatics, mechanics, and electronics, so the individual needs a strong knowledge base of these processes.”
Schafer recommends that biomeds who are interested in this area gain as much exposure as they can in other areas within the hospital, such as monitoring or infusion, before trying to specialize in respiratory equipment. After 2 years of general medical equipment experience, they are then adequately prepared to enroll in ventilator training classes.
Jim Bogett, president of Omnicore Medical Services Inc, Syracuse, NY, finds that increasing numbers of biomeds are choosing not to specialize in this area due to the time commitment involved in the training process. As a result, with this type of shortage, the future looks bright for those committed biomeds who are attracted to both the challenges and rewards of working on life-support systems that play a critical role in patient care.
Jim Bogett, president of Omnicore Medical Services Inc, Syracuse, NY, agrees that every manufacturer has a different philosophy regarding how often PM should be performed on its ventilators. However, he says in general a full functional performance certification evaluation is conducted a minimum of every 6 months, and in some cases it is performed at specific hourly time intervals. For example, some ventilators require a filter change every 3,000 hours. In addition, most machines undergo a periodic extended self-test (EST). Wright adds that individual hospitals often set their own policy regarding PM, with his employer requiring each machine to undergo an electrical check every 6 months.
Types of Repairs
Since ventilators are bulky, servicing is almost always done on-site. Ventilator reliability has improved over time, allowing today’s biomeds to focus on PM rather than specific repairs. However, according to Sanger, if there is one area that does receive more attention in terms of servicing it would be the exhalation module. “Since most critical care ventilators measure what the patient exhales, the exhale gas coming from the patient can be fairly hostile, since it’s exposed to medication, moisture, and heat,” he says. “If the operator does not maintain the filter properly, some of these gases can cause damage to the ventilator.”
Although this equipment is mostly fail-safe, patient circuits have a tendency to leak. Respiratory therapists are generally required to perform periodic self-checks to ensure that the circuit passes leak and compliance tests and that the ventilator is calibrated properly. If a leak alarm goes off and the respiratory therapist cannot find the source of the leak, biomeds are asked to perform an EST and repair.
“In most instances, you would use the same circuit for up to 15 days,” Sanger says. “If you have a patient on the ventilator for a long period of time, you may have to change out that circuit every other day and run a self-test. If the therapist doesn’t understand what the tests are doing, he or she often thinks the machine isn’t working properly, but then the biomed discovers that all it needs is a new patient circuit.” Because numerous problems arise from the circuits and not the actual machines, Sanger instructs biomeds in his training classes to make sure they have accurate test equipment and known-good patient circuits.
Bogett notes that the newest machines seem to require less maintenance than earlier generations. “The biggest change is that touch screens and panels are replacing dials and knobs, which would wear out over time,” he says. “Now, with this digital technology, all you do is replace the circuit boards.”
Regular communication with the respiratory therapy staff also results in fewer service calls. Wright conducted research in his hospital for a college course to see how many calls to the biomed department could have been avoided with additional training of the therapist staff. “I found that 50% of the calls were actually cases in which therapists could have solved the problem by themselves,” he says. As a result, Wright developed a training program that addressed ventilator use and troubleshooting strategies. After the therapists participated in the training, there was a 100% improvement in the number of unnecessary calls made to the biomed department.
Carol Daus is a contributing writer for 24×7. For more information, contact .