Optimizing patient-ventilator interaction is challenging, and not necessarily made easier by the complexity of today’s ventilators and plethora of ventilation modes. Simulators allow learners to gain hands-on experience with a wide variety of patient scenarios.

Engineers and researchers may also use breathing simulators and test lungs to develop, evaluate, and test ventilators, says Susan Petersen, director of marketing, IngMar Medical Ltd, Pittsburgh, Pa. Here’s a look at some current simulator device offerings in the marketplace.

The Michigan Lung

Michigan Instruments’ Training and Test Lung, or “Michigan Lung” and its newly developed PneuView 3 software are products designed for simulation of the human pulmonary system, allowing reproduction of hundreds of different patient scenarios of respiratory pathologies.

Full to scale in regards to mechanical design, the device simulates patient breathing by having lungs rise and fall. It can measure many different pulmonary parameters.

Six different models are available—single adult lung, dual adult lung, and adult/infant models in both instrumented and non-instrumented versions. It is light enough to carry, and easily fits on a cart or tabletop for easy operation.

According to Joe Baldwin, president, Michigan Instruments, Grand Rapids, Mich, a new user interface for the PneuView 3 software makes monitoring, reviewing, and reporting easy and efficient.

All units come as a complete package ready for use. Instrumented units include a computer with pre-installed software. The test lung offers simple and intuitive setup, and only requires calibration every two years.

Hans Rudolph’s DLco Simulator with Easy Lab QC Software

The Series 5560 DLco Simulator with Easy Lab QC Software from Hans Rudolph Inc., is used to test the operation and calibration of single breath DLco (lung diffusion capacity for carbon monoxide) systems. “It can simulate a wide range of DLco values to test the full range of operation of the device,” explains Kelly Rudolph, president, Hans Rudolph Inc, Shawnee, Kan. “By using two or three different precision gas blends, it is possible to determine if a problem is caused by the gas analyzer or the flow measuring part of the equipment. This is very useful in troubleshooting and repair operations.

The DLco Simulator uses a calibrated syringe to simulate the tidal breathing and the inhaled volume. By using a known precision inhaled volume, the flow measuring component of the DLco device can be tested. The simulated patient exhale is performed by using a second syringe to deliver a volume of precision blended gas that accurately simulates the exhale of a patient. If the gas analyzer is not working correctly the concentrations for the carbon monoxide and tracer gas will be incorrect.

The simulator is mounted on an adjustable roll stand that also has baskets to hold up to three gas tanks used for the simulation. “This makes it very easy to move the simulator to the device being tested and adjust it to the normal patient mouth position,” Rudolph says.

Regular use of the DLco Simulator along with the included Easy Lab QC Software will provide needed information on the accuracy of the device being tested as well as historical data that will make it easy to recognize when the device is changing and may require calibration or service. “By testing over a wider range of DLco values, a better check of the equipment is made than can be done by using a person as a standard biological sample,” Rudolph says.

The information also provides details on what part of the system may be operating incorrectly. The accurate simulation of DLco tests can save considerable time and money by preventing retesting of patients if the equipment is later found to be working incorrectly. It can also save money by focusing attention on the particular problem with the device and being able to run tests to see if the problem has been fixed. This could save repeat service calls and reduce down time.

Hans Rudolph’s Series 1120 Flow/Volume Simulator 

Hans Rudolph Inc’s Series 1120 Flow/Volume Simulator is used to generate repeatable and accurate complex flow waveforms. The most common use for this device is to generate the simulated exhale waveforms that are used to verify the operation and accuracy of spirometers and peak flow meters. This requires a volume capacity of 8.5 L and flow capability up to 15 L per second.

The complex waveforms specified by the American Thoracic Society and International Standards Organization standards for spirometers can be reproduced by the flow/volume simulator. In addition to these waveforms, users can define a complete breath cycle and use the simulator to recreate this breathing flow pattern repeatedly as a breathing waveform.

By using a precision flow profile, it is possible to easily compare the spirometry values for the delivered flow profile to the values reported by the device being tested. “This can help the user determine if the device is working properly or if there is a problem with a particular measurement or if the flow calibration is correct,” Rudolph says.

The simulator is very repeatable, which is important for checking the repeatability of a device and also when developing new devices to ensure that they work properly over the full range of flows.

The flow/volume simulator uses a precision servo motor and control system to move a piston in a cylinder to create the flow profile that is requested. “The motion of the piston is precisely measured during the motion and is then used to calculate the flow generated,” Rudolph explains. The cylinder pressure is also measured and is used to correct the calculated flow to account for compression of the air in the cylinder due to the resistance of the outlet and the device being tested. This gives an accurate measurement of the volumetric flow actually exiting the device being tested.

A Windows software package interfaces with the flow generator to provide the user interface. The software allows the user to select the operating mode, waveform, or breathing pattern to be generated and then it displays the delivered flow and pressure waveform. In the single breath mode—which is used for spirometry testing—the calculated spirometry values are also displayed so the user can easily compare these values with those reported by the device being tested.

Little maintenance is required because there is only one moving part. Re-calibrations can be performed in a local lab or the device can be returned to Hans Rudolph for calibration.

CAE Healthcare’s HPS and PediaSIM HPS

Designed for anesthesia, respiratory care, and critical care, CAE Healthcare’s HPS (Human Patient Simulator) provides true respiratory gas exchange. “For hospitals, medical and nursing schools, and military bases, the HPS offers residents and clinicians the rare opportunity to experience and react to crisis situations without jeopardizing real patient safety, says Pamela Azevedo, product manager for patient simulation, CAE Healthcare, Saint-Laurent, Quebec, Canada.

The HPS’s lungs consume oxygen, produce carbon dioxide, and intake and eliminate real anesthetic gases in accordance with the principles of uptake and distribution. This capability is made possible by direct gas exchange within the lungs resulting in realistic inspired concentrations, exhaled concentrations, and minimum alveolar concentrations. Furthermore, HPS has clinical features and intervention capabilities to bring medical education to a new level of realism. Some of these include palpable pulses, self-regulating control of breathing, heart, breath and bowel sounds, electrocardiograms, pulmonary artery pressure, and cardiac output.

The HPS interfaces with clinical monitors and fully supports mechanical ventilation, with automatic responses to continuous positive airway pressure, pressure support ventilation, synchronized intermittent mandatory ventilation, assist control modes, and weaning protocols. Operated by the Müse interface, its programming allows instructors to set variable airway resistance, lung compliance, chest wall compliance, and independent control of the right and left lungs.

Its Drug Recognition System identifies drug concentration and volume with pharmacokinetic modeling for more than 60 intravenous drugs. CAE Healthcare patient simulators are built upon physiological models that adapt to interventions based on a patient’s age, weight, underlying health conditions, and the accuracy of diagnosis and treatment.

The PediaSIM HPS is a child-sized patient simulator that was modeled from a body scan of a 6-year-old boy. PediaSIM HPS also offers true gas exchange and the clinical features of the HPS, but with the realistic modeling of pediatric cardiovascular, respiratory, and neurological physiology.

CAE Healthcare’s Fidelis Lucina

CAE Healthcare’s newest patient simulator gives birth; it can even simulate both normal deliveries and obstetrical emergencies for hospital teams. Lucina is fully wireless, and is the only patient simulator that supports a full maternal code as a gravid or non-gravid patient.

“Lucina is changing the way teams prepare for high-acuity, low frequency obstetrical emergencies, like maternal cardiopulmonary arrest,” says Azevedo. Its realistic airway accepts most airway management adjuncts. Its advanced lungs support mechanical ventilation with spontaneous ventilation.

Lucina’s cardiopulmonary resuscitation performance analysis metrics measure the quality and depth of chest compressions, ventilation rate and volume, coronary and cerebral profusion pressures, and cardiac output to aid learners during debrief. “She offers a realistic airway and neck articulation that allows her to be placed in the sniffing position,” says Azevedo.

The mother and fetus have integrated physiology that can be monitored on a realistic fetal monitor. The baby’s vital signs respond to labor maneuvers and emergency treatments. “The simulator delivers one-minute and five-minute Apgar (appearance, pulse, grimace, activity, respiration) scores that are based on team performance, an invaluable tool for debrief,” Azevedo says.

CAE Healthcare has developed evidence-based simulated clinical experiences for the Lucina patient simulator, including acute respiratory distress syndrome, chronic heart failure, sepsis, and post-partum hemorrhage. The experiences can be launched within the Müse interface with a few clicks, and they include learning objectives, debriefing questions, and references.

IngMar Medical’s RespiSim System

The RespiSim System is a ventilator management training system. At its core is the high-fidelity ASL 5000 breathing simulator. “These ‘ventilator grade’ lungs are able to simulate almost any patient breath (neonatal to adult), enabling effective instruction in ventilator management,” says Petersen says.

The RespiSim software simplifies management of multistage patient scenarios using the ASL 5000 and allows instructors to stay in control of the simulation. “Instructors can amplify effects, throw students a curveball, or get the simulation back on track to ensure that learning goals are met,” Petersen explains. “Students get the full view of patient-ventilator interaction, from vitals to x-rays, in structured, multi-stage simulations.”

The system is modular, making it easy to add components as needs and budgets expand. The ASL 5000 can be integrated into the RespiPatient, manikin for enhanced realism and expanded skills training. RespiPatient can provide realistic positive end expiratory pressure, chest rise, lung, and bowel sounds and also offers the ability to train procedures such as intubation, needle decompression, tracheotomy, and chest tube insertion. The RespiScope Advanced Auscultation Option uses a unique WiFi stethoscope. This technology eliminates stray noise from the inner workings of the manikins, providing exceptional sound quality.

RespiPatient is a compact torso-only manikin that can be mounted onto a mobile cart for ease of transport and compact storage. “The cart enables the RespiSim System to be easily moved from the simulation center to the intensive care unit to rehearse real patient scenarios using real patient data,” Petersen notes.

The RespiSim System also offers plug-and-play curriculum Modules developed in collaboration with leading educators. “The modules save instructor time by providing a comprehensive, multi-media package of materials that give the instructor everything he or she needs for the simulation, including preparatory lecture material for the students and questions to ask during the simulation and debriefing,” Petersen says. Individualized hands-on training is offered at the customer site.

The RespiSim System can be used for training on any ventilator.

IngMar Medical’s QuickLung Breather

The QuickLung Breather is an actively breathing test lung for ventilator testing and management training. “Beyond providing a mere trigger for the ventilator, the QuickLung Breather can simulate the spontaneously breathing patient in a variety of modes and patterns,” Petersen says. “This opens up new opportunities to demonstrate and test ventilator triggering and important modes of ventilation such as synchronized intermittent ventilation), pressure support, and proportional assist ventilation. It’s compact, with just a 7.5 by 11-inch footprint.

Patients can be quickly created by choosing from five breathing patterns: Eupnea, Cheyne-Stockes, Biot’s, Kussmaul, or Apneusis and customizing parameters (ie breath rate, volume, inspiratory:expiratory ratio). Three compliance settings (ie 50, 20, 10 mL/cm H2O) and three resistance settings (5, 20, 50 cm H2O/L/s) allow for the simulation of a wide range of patients from pediatric to adult.

QuickLung Jr version enables the simulation of smaller pediatric patients. Resistance (Rp5, Rp20, Rp50) and compliance (C50, C20, C10) settings correspond to International Electrotechnical Commission ventilator performance standards. Setup is easy, as no external gas source is required.

The QuickLung Breather can be used for training on any ventilator.

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Karen Appold is a contributing writer to RT Magazine. For more information, contact [email protected]