Cardiopulmonary Resuscitation – CPR is a recurring practice in medical urgency and emergency. CPR is characterizes by a set of maneuvers performed in an attempt to reanimate the victim of cardiac and / or respiratory arrest and is intended to cause the heart and lung to return to their normal functions while maintaining oxygenation of the brain. This scenario represents an extreme medical emergency, which can lead to irreversible brain injury and even death if appropriate measures to restore blood flow and breathing are not performed properly. Thus, students and professionals in the area must acquire skills that enable them to act quickly and efficiently during patient care. This work proposes to adapt an existing sensor and embed on mannequins used in CPR training to accurately measure the amount of air supplied to the lungs during ventilation. The proposed sensor consists of measuring the airflow using propellers. The method directly measures the variable of interest and makes reference to expirometric techniques in the elaboration of its model, improving the realism of the dummies. The projected sensor presented an agreement with its theoretical model and with the expirometric model, besides advantages over the sensors that are used for this purpose. It was suitable for applications with an accuracy of ±17 mL, and resolution of 50 mL and 26 mL for initial and final measurements, respectively, ranging from 30 to 1800 mL.
1) Was the pressure required to enter the volume of air in an real lung compared to the pressure required to make the air pass through the sensor?
2) The pneumatic circuit used in the assembly was not presented in the work. How was air introduced into the pneumatic circuit? Is there a reservoir on the exit emulating the behavior of a lung, or is the outlet an open tube for the atmosphere?
3) How is the interface with the operator? Is there an indicator? How were numerical data entered into the computer for graphing?
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Question 1:
According to Kulish (2006), in one hundred percent of vital capacity the inspiratory muscle pressure can reach a maximum of 30 cmH2O and the expiratory muscle pressure can reach a minimum least -30 cmH2O. Thus, the maximum pressure difference in the lungs, both expiratory and inspiratory, is 60 cmH2O. Most mechanical ventilation devices have a safety valve that operates at a pressure of 60 cmH2O, so this is the maximum pressure that can be had in mechanical ventilation. The pressure required to make the air pass through the sensor is negligible compared to 30 cmH2O. Since at the end of the process there is an open tube, the pressure at this point is atmospheric, so the pressure difference at the inlet and outlet of the device does not exceed 6%, considering the pressure required to make the air pass through the sensor. Thus air can be considered as an ideal gas, which is a boundary condition adopted to simplify the theoretical model developed in this work.
Question 2:
The sensor installed on the manikin follows the flowchart of Figure.
Mechanical ventilation can be done by devices dedicated to this purpose or even mouth-to-mouth. The unidirectional valve A has the purpose of not letting contaminated air return to the person performing the maneuver, that is, a matter of hygiene and health. The sensor measures the volume of air entering the lung (the manikin has a single lung with a volume of 3500 mL, to simplify the model). The lung in turn stores ventilation air. The unidirectional valve B serves two purposes. Prevent return of the lung air to the sensor and manage the flow of air exiting the lung into the atmosphere. It is also responsible for thoracic expansion without changing the pressure of the entire system. In this way, the contour conditions imposed by the theoretical model on the device installed inside the manikin were met.
Question 3:
For this work the arduino platform monitor was used for data sampling and a unique software to draw the graphs. A future work that is already in the implementation phase uses arduino as prototype that collects the data in real time, that is, a Soft Real-Time System and transfers to a interface with the operator through RS-232 communication via USB. The interface with the operator is being developed in Visual Studio and has an indicator that works in conjunction with a real-time chart. The interface with the operator has a methodology for teaching ventilation, real-time feedback containing ventilation information and a game mode that is still in the planning stage. The final product will be implemented using PIC family microcontrollers (Microchip) and Wi-Fi communication, making the product versatile for numerous applications.
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Thank you.
I appreciate your interest in the job.
The work employ concepts of Biomedical Engineering, an area interdisciplinary that involves Engineering, Exact and Earth Sciences, and Life Sciences.
The text looks complex because you lack knowledge of Engineering and Exact and Earth Sciences. If you have been studying medicine for less than two years, your cognition in life sciences also is not enough.
If you want to improve your knowledge to understand this work, I am willing to help and clarify any questions you may have.
Yours sincerely,
Rodolfo Leocádio
