a new practical scheme for verification of pulmonary
Contents
1. shows the loading probability and provides information about the need to change the ventilation mode O Pmean the mean pressures during the ventilator cycle shows the fluid pressure introduced into the lungs and provides information about the maximum pressure level that can decrease or not e The volumes o VT Inhale Tidal Volume the gas volume delivered by the ventilator into the patient s lungs and shows comparing it with the VT exhale tidal volume the leakage level and the intubation s quality o VT Exhale Tidal Volume shows how efficiently the patient is ventilated o MV Minute Volume shows how well the patient is ventilated over time unlike the quality of the VT that ilustrates the ventilaion quality for a single breath e The frequency O tinhale inhale time together with the texhate exhale time influences the IE ratio level the inhale exhale ratio o t the inhale time period in whitch the gas is introduced into the lung The Romanian Review Precision Mechanics Optics amp Mechatronics 2011 No 40 49 A new practical scheme for verification of pulmonary ventilators used in human medicine o t the inhale time period in whitch while the VT tidal volume is kept constant the gas does not enter O texale exhale time o f frequency respiratory rate O fspont Spontaneous frequency is the spontaneous breathing level and describe if the chosen2. and flow values The computer also processes the data received from the sensors and provides the values of the main respiratory parameters the maximum pressure the PEEP the plateau pressure the VT the inhale and exhale times the respiratory rate the inhaled gas oxygen concentration The ventilator on which determinations were made with this scheme is a Dr ger Savina The Savina equipment has been previously tested according to the manufacturer s documentation and has passed all tests The main features of this ventilator are presented in Table 1 Table 1 Features of the Drager Savina ventilator feature Respiratory rate min tinhale s gas flow l min VT ml accuracy Tow Pinnaie hPa 099 PEEP hPa O 6 This Paper s Developed System Constituent Parts To create the testing system the following parts were used Pressure sensor SQ 99835 Honeywell type 8 Fig 6 Pressure sensor SQ 99835 Honeywell Flow Sensor Honeywell AWM5000 9 Fig 7 Flow sensorAWM5000 Honeywell Oxygen sensor Dr ger Mainstream L i T ager 0 Sensol Fig 8 Oxygen sensor Drdger Mainstream The data Acquisition Card is an USB 6009 type produced by the National Instruments o o o e i a o 8 e e e Fig 9 Data Acquisition Card USB 6009 52 The Romanian Review Precision Mechanics Optics amp Mechatronics 2011 No 40 A new practical scheme for verification of pulmonary ventilato
3. A new practical scheme for verification of pulmonary ventilators used in human medicine A NEW PRACTICAL SCHEME FOR VERIFICATION OF PULMONARY VENTILATORS USED IN HUMAN MEDICINE Doru Dumitru Palade Bogdan Marius Ciurea Sorin Kostrakievici National Institute of Research amp Development for Mechatronics and Measurement Technique 6 8 Str Pantelimon Bucharest Romania Dr ger Medical Romania 14B 16 Str Nisipari sector 1 Bucharest Romania University Politehnica of Bucharest Dept of Bioengineering and Biotechnology 313 Spl Independentei 060042 Romania Abstract The ventilation equipment s proper operation is mandatory to ensure the medical act s success The pneumatics lung ventilator testing is not standardized and it is established by the manufacturers The usual ventilators test systems can t measure accurately all the ventilators parameters This paper proposes a test unit that can be used for a big ventilation equipment majority This system follows to measure the ventilator s parameters that can t be accurately measured by conventional systems Keywords test equipment lung ventilator 1 Introduction The ventilator is the equipment that sustains the patient breathing when he totally or partly loses the respiratory function Whereas it is vital to maintain the patient in life it has to be known whether the ventilator works or not in the designed parameter ranges stipulated in the technic
4. al documentation The ventilation systems producers have developed their own test systems There are international standards that provide the tests that should be performed for the equipment s electrical safety Typical electrical measurements are performed according to standards IEC 60601 IEC 62353 In the human ventilator s pneumatics area there are no specific standards for the moment The ventilators usually have incorporated various types of sensors e g pressure flow temperature CO2 concentration O2 concentration that monitor various parameters The producer s tests refer to verifying sensor calibration voltage and check the sensor s response for different values standardized by each producer with calibrated and verified metrology equipment For a better evaluation of the ventilator the system should be tested by introducing values that should simulate critical situations to verify the occurrence of certain alarm states The main measuring and testing parameters are 1 e The pressure O Pmax the maximum pressure a high pressure fluid can damage the lungs especially for the newborns o PEEP the Positive End Expiratory Pressure can lead to alveoli collapse when it is too small or at an insufficient exhale level for high PEEP levels O Pplateau the plateau pressure plateau pressure witch shows the pressure level for a given tidal volume O Prigger the trigger pressure in the patient s circuit
5. ected via a hose directly to the Y piece 7 and the flow sensor 6 is connected between the lung simulator 5 and the Y piece 7 The ventilator 1 introduces the inhaled gas at a preset flow and pressure values by the inhale block 3 The gas is analyzed in terms of oxygen concentration by the oxygen concentration sensor 11 Depending on the oxygen concentration in the inhaled gas it provides a certain electric voltage to the data acquisition card 9 Its value is read using the LabView software and displayed on the computer s display 10 The pressure in the patient system 4 is determined almost constant by the pressure sensor 8 Sensor 8 provides various electrical signals for various pressures which are viewed through the data acquisition card 9 and the LabView software on the computer s display 10 The gas flow rate is determined by the sensor 6 and viewed on the computer s display 10 similarly to the pressure rate All data are retrieved and displayed in real time The exhale is made by the ventilator through the exhale valve 2 The gas pressure and flow are monitored by the exhale pressure sensor 8 and by the flow sensor 6 and their values are viewed on the computer s display 10 For the proper functioning of the system a computer program is developed in the LabView software 5 7 This program is converting electrical voltages from the oxygen concentration pressure and flow sensors into oxygen concentration pressure
6. ermined by the flow meter 3 The pressure reading from the pressure gauge 2 which is connected through the connecting sleeve 1 to the inhale valve must be in the 80 120 mbar range Fig 3 Inhale block emergency valve check diagram 50 The Romanian Review Precision Mechanics Optics amp Mechatronics 2011 No 40 A new practical scheme for verification of pulmonary ventilators used in human medicine A fluid flow of 59 to 61 l min is generated through the flow meter 6 using a test pressure regulator 1 and injector 2 The pressure monitored by the pressure gauge 7 should be in the 6 3 bar interval The hoses 10 the Y piece 9 the sealing plug 8 the silicone tube 3 connecting sleeve 4 and ISO socket 5 are used to enable the assembly e ventilation testing The IPPV mode is set VT 500ml t 2s f 12breath min PEEP S5mbar FiO 21 and the values provided by ventilation equipment are read on the display The values are checked to be in tolerance ranges provided by the producer A different value for the oxygen concentration FiO 60 is chosen and the measured value is read and shown on the display This value is compared with the determined value from the oxygen analyzer 2 that is mounted in parallel with the patient 5 through the T shape piece 1 The PEEP pressure is check with the pressure gauge 6 connected to the patient 5 through the Y piece 4 and the hoses 3 C Fig 4 Ventilation testin
7. g diagram The BIPAP mode is chosen and the following values PEEP 5mbar ti 5s f 6breth min Pinhale mbar and the values provided by the ventilation equipment are read on the display These values are compared with the Pinhae and PEEP read on the pressure gauge 6 and checked if they are in the tolerance range from the producer s service manual The volumes are verified by comparing the VT to the VT and the volumes should not differ by more than 15 4 Conclusions on the Classical Testing In classical ventilator testing it can be seen that the VT VT and MV values are verified only with the ventilator s sensors by comparison but there is no certainty that the ventilator s flow sensors are in normal ranges or not Classical testing can not determine the frequency and inhale and exhale times All data about those times are available only on the ventilator s display In some cases these times are determined by the technician In such cases only the inhale and exhale times and frequencies are determined but with the technician s response time errors The plateau time can not be determined The pressures are determined by reading the maximum and the minimum value on a manometer connected in parallel with the patient and compared with those displayed by the ventilator The maximum and the PEEP pressure can not be exactly determined The plateau and the mean pressure can not be monitored externally For oxygen concentra
8. ressure datasheets ht ml 9 http content honeywell com sensing prodinfo massairflow installation p88762_3 pdf 10 http www draeger com media 10 01 76 10017 640 02 sensoren_br_9049119_en pdf grotto un veges pu EN The Romanian Review Precision Mechanics Optics amp Mechatronics 2011 No 40 53
9. rs used in human medicine 7 Conclusion This testing system can be used for most of the ventilation equipment There is only one test equipment The system s flow and pressure sensors are different from those of the ventilation equipment and such they can check the ventilator s sensors by comparison This system automatically determine all the parameters Pmax PEEP Pplateau Ptriggers VT Vie MV tinhates ti t2 texhae inhaled gas O2 concentration without human error The parameters are determined automatically by the system the only error being given by the sensor s precision and calibration and by the sampling rate 8 Bibliography 1 Robert L Chatburn Fundamentals of Mechanical Ventilation A short course on the theory and aplication of mechanical ventilators ND Manu Press Ltd Cleverland Heights Ohaio 2003 2 Test Instructions Service card IPM Savina revision 1 0 Lubeck Germany 3 Galileo service manual Hamilton Medical AG Bonaduz Switzerland October 2005 4 700 Seris Ventilator Systems Service Manual Mallinkrodt St Louis 1999 5 Robert L Chatbur Computer Control of Mechanical Ventilation Respiratory care may 2004 vol 49 no 5 6 Sever Pasca Instrumentatie virtuala Cavallioti Bucuresti 2007 7 Arthur S Slutski Laurent Brochard Mechanical ventilation Update in intensive care medicine Springer Berlin Germany 2005 8 http www ssec honeywell com p
10. rting a timer at the begining of an inhale phase and counting the inhale number for one minute The t and t times can hardly be determined They are determined only by viewing the guide filling and maintaining the inflated lung simulator The oxygen concentration is determined by connecting the oxygen concentration sensor to the inhale deviation The temperature is determined by mounting a thermometer on the inhale deviation 3 Testing a Ventilator Type To demonstrate it is shown a Savina equipment test system 2 The check consists of checking various subset unit series numbers checking data equipment checking user settings checking the general state of the ventilator testing electrical safety and power supply testing keyboard and display testing inhale and exhale blocks To test the ventilation equipment the following measure schemes are used Using the syringe 1 slowly permissible pressure change less than 1 mbar s build up a pressure of 2 5 mbar 0 5 mbar at the outlet of the exhale valve The volume injected through the syringe in one minute must not exceed 35 ml Pressure is monitored by pressure gauge 2 connected in parallel with expiratory valve 4 by connector 3 and T shape piece 5 D aa S Fig 1 Diagram for testing the non return valve in the exhale block Fig 2 Inhale block safety valve check diagram A flow regulator 4 is generating gas at a flow rate of 2 3 l min It is det
11. tions temperatures and anesthetic concentrations testing are required other equipment The human factor the one that generates a lot of errors is quite present in the various parameters determination As a results of the previous observations its obvious the need for a new and complex system that would be able to determinate the pressures PEEP Pinhak Pexhales Pplateauy APasp the inhale and exhale volumes VT VT Minute Volume MV the inhale and exhale times t te the frequency f and the inhale exhale ratio I E the oxygen concentration FiO the anesthetic and CO concentrations and the gas temperature 5 Proposal for a Lung Ventilator Verification System This paper presents a lung ventilator verification system designed for fast and accurate breathing equipment checking Fig 5 The test system diagram The ventilator s test system shown in Fig 5 consists mainly of the pressure sensor 8 the flow sensor 6 and the oxygen concentration sensor 11 connected through the data acquisition card 9 to the computer 10 on which is installed the LabView software The oxygen concentration sensor 11 is connected to the ventilator circuit consisting of hoses 4 between the inhale block 3 and the Y piece 7 The pressure The Romanian Review Precision Mechanics Optics amp Mechatronics 2011 No 40 51 A new practical scheme for verification of pulmonary ventilators used in human medicine sensor 8 is conn
12. ventilation mode is adequate e The gases concentration o inhaled gas O2 concentration is the ventilator s loading level that needs to relate to the body s oxygen demand o exhaled gas CO concentration the ventilation level related to the hyper or the hypo ventilation o anesthetic gas concentration represents the patient s sedation level e The inhaled gas temperature the inhaled gases temperature level for a successful thermoregulation 2 Classical Testing General Information Testing the pulmonary ventilators is done using lung simulators Pressure values are achieved connecting a manometer in parallel with the lung simulator 2 4 The technician monitors the maximum and minimum pressures The plateau pressure determination requires an experienced technician He must oversee the lungs s filling state and consider the plateau pressure the value for which the lung is maintained inflated The volumes check is done by reading the VT Tidal Volume value on the ventilator s display and compare it with the seted one The techician establishes the inhale and the exhale time with a stopwatch by pressing start and stop at the inhale and exhale beginning and end The measurement is not accurate because it depends very much on the human factor The smaller respiratory times determination can not be achieved because of the technician increased time reaction as in neonates The frequency is determined by sta
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