Modern medicine requires highly qualified specialists and the demand for them is growing every year. Various technologies are being used to prepare them, for example, medical artificial body organs and simulators - this is an advanced teaching technology that allows you to show practical situations and develop the necessary knowledge and skills of doctors. The use of simulators in training of medical personnel can significantly reduce the likelihood of medical mistake and increase the safety of medical care.

Medical artificial body organs and simulators are one of the most emerging markets with a stable growth rate of 14% according to Allied Market Research. The largest global market for medical instruments and simulators is currently in North America, with the largest growth rate in countries in Southeast Asia.

Classification of medical simulators

According to the Russian society for simulation training in medicine (ROSOMED), there are 7 levels of realism of training sessions:

  • visualization
  • haptics (tactile sensitivity)
  • natural motorics and ergonomics
  • video image
  • equipment
  • interactivity
  • good communication skills

There are different types of simulators for different types of trainings. One of the first type of simulator was proposed in 1987 by M. Miller. Over time, several types of simulators arrived and now the typology of six levels of simulation techniques, which was proposed in 2007 by G. Alinye (Great Britain) is widely known. The classification is based on comparison of the functions of simulators, the degree of involvement of students and realism of their experience that can be obtained with their help.

  • Level 0 - written simulators (clinical situational tasks)
  • Level 1 - volumetric models: low-realistic mannequins, skill simulators
  • Level 2 - "having screens": computer situational tasks, test programs, videos, virtual reality simulators
  • Level 3 - standardized patients and role-playing games
  • Level 4 - middle-class mannequins with electronic or computer control
  • Level 5 - computer mannequins - simulators of the patient of the highest class of realism

But in modern realities, these six levels are no longer enough. According to the classification of G. Alinye, in everyday practice, private practical typologies related to certain areas of medicine are used for training. For example, for laparoscopic training in surgery, the following methods are used:

  • box simulators
  • video simulators
  • virtual simulators

ВIn the sector of emergency therapy uses two different types of medical training devices:

  • simulators for individual practical skills (Task-Trainer, Skill-Trainer)
  • patient simulators (low-realistic low-Fidelity dummies, middle-Class patient simulators, high-realistic Hi-Fidelity robots

Creation of medical simulator

Our company has experience of creating medical simulator, we have created blood pressure meter simulator. Measuring of blood pressure is carried out by Tonam Korotkova.

Historical background: The korotkov method is a sound(auscultative) method of measuring blood pressure, proposed by the Russian surgeon Nikolai Sergeyevich Korotkov in 1905. Currently the korotkov method is the only official method of non-invasive measurement of blood pressure, approved by the World Health Organization(WHO) in 1935. Pressure measurement is performed using a tonometer (sphygmomanometer) , and listening to Korotkov’s tones from a pulsating clamped artery with the help of a stethoscope.

The simulator is designed to practice the skills of measuring blood pressure. The control unit consists of:

  • analog pressure sensor
  • microcontroller
  • touch screen display

The device is developed by us which imitates heartbeat depending on blood pressure and simulates a pulse for palpation. The device allows you to set several imitation modes:

  • with and without palpation
  • with and without auscultative failure

The device settings allow you to set the following parameters:

  • systolic blood pressure
  • diastolic pressure
  • heart rate
  • the volume of the sound of the heartbeat
  • imitations modes

Sound output occurs on a standard speaker 2 W, resistance 4 Ohms. Pulse imitation is performed by a retracting solenoid.

The speaker and solenoid are built into the silicon model of the human hand – the speaker in the area of the elbow bend, the solenoid in the area of the radius, that is, in the places where pressure and pulse are determined.

For us, the most difficult thing was to imitate heartbeat sound in different operating modes and different frequencies. We recorded the necessary sounds and after computer processing were able to simulate them in our device.

The second most difficult task was the selection of a pressure sensor. Taking into account the situation on the market of electronic components, we focused on the Chinese market and spent a lot of time searching for a supplier of high-quality pressure sensors with stable characteristics.

The third issue that needed to be addressed was the correct imitation of optional failure. For a better understanding of this issue, we asked for advice from cardiologists, as a result, we came to the following logic of work:

Turning on the device

  • Palpation function is enabled. The solenoid knocks. There is no sound
  • SYS (systolic pressure)
  • DIS (diastolic pressure)
  • Begin to pump the air and increase the pressure. The pressure becomes higher than systolic SYS by 20%, this is the moment when the measurement begins.

There are two modes of operation:

  • Auscultative failure is enabled (GAP ON, top half of diagram in Figure 1)
  • Auscultative failure is disabled (GAP OFF, bottom half of diagram in Figure 1)

Figure 1. Diagram

Audio playback when ascultative failure is disabled

  • Blood pressure decreases to systolic SYS.
  • The entire scale between systolic (SYS) and diastolic (DYS) pressure is split in half
  • Sound 1 is played first, the solenoid is switched off
  • Then, before reaching the middle by 5 mm Hg, Sound 2 starts
  • After passing the middle, another 5 mm Hg sound 2 stops
  • Sound 3 is played with the volume level reduced by 10-20 % from the one configured in the parameters
  • Further, before reaching the diastolic pressure limit of 5 mm Hg, the volume decreases by another 30% and stops when the diastolic pressure is reached
  • The solenoid is activated when the pressure drops below 20 mmHg.

Audio playback with ascultative failure enabled

When the AP function is enabled, another threshold is added in the first half (see figure 1). This is the quarter threshold between systolic and dystolic pressure. It is counted down from the systolic pressure. After reaching this threshold, the sound stops until the sound start condition 2 appears.

Matching sound and heart rate

Sound 1, Sound 2, Sound 3 are correspond to the pulse rate that is set in the settings, that is, the corresponding file is launched from the flash card.

In real life, each person has their own" pause " rhythm, but for the purposes of creating a simulator, this algorithm was enough.

Development of the device

In the process of implementing the project, two versions of the printed circuit board were developed, first a basic one, and then an improved and modified one, in which we corrected all the shortcomings found.

One of the advantages of the device developed by us was in reasonable price, which we managed to keep at the level of Chinese analogues. It is also worth noting the high quality of the device and realistic imitation of heartbeat sounds and it’s comparable to Western "branded" devices.