with particular reference to fig1 and 3 , the feeding lines can be observed of oxygen and air , respectively o 2 and a , to the proportioning unit 1 wherein the percentage oxygen in the feed mixture is determined within a range between 21 and 100 %. the mixture ( o 2 and a ) so obtained passes from that unit to the flowmeter 2 wherein the feed flow to the inhalation conduit 3 can be adjusted within a range of values between 0 and 20 l / minute . a valve 4 ( vmax ) limiting the value of the inhalation pressure ( pip ) is provided in said conduit 3 , such valve intervening in correspondence to a maximum value set forth previously for the inhalation pressure . the humidifier - heater 5 is provided along said conduit 3 downstream to valve 4 , said humidifier - heater being controlled by the servo system 6 . the conduit 3 is connected to the patient p who has been intubated previously through the three - ways connection unit 7 . the conduit 8 for the expiration air and the conduit 9 which is connected through a transducing unit 10 to said electronic processor unit 11 which is provided with a monitor , are both connected to said connector 7 . a pinchcock solenoid valve 12 is provided along said conduit 8 , said solenoid valve operating on the outer surface of said conduit so as to warrant optimal boundaries to the sterility conditions . the conduit 8 has at one of its ends the valve 13 ( v min ) intervening for opening said conduit and for discharging the inhaled air till the expiration pressure ( peep ) reaches the minimum pre - established value ( fig3 ). as a matter of practice , the flowmeter 2 dispenses a constant flow of air and oxygen which flow through the ventilation circuit 3 ; the valve 12 closes intermittently and for a predetermined time ti the expiration way so as to deviate the gas flow to the patient ( fig1 ). as already mentioned above , the basic parameter for the ventilation of the patient is the insufflation pressure ( pip ); when such pressure reaches the desired level inside the circuit , any excess of gas that is possibly present is eliminated into the environment by the valve 4 ( v max ) that limits the value of maximum pressure , and is arranged along the inhalation way 3 . this fact allows the fine adjustment to be obtained of the maximum inhalation pressure and also allows such pressure level to be kept during the whole further inhalation time ( fig2 ). the valve 13 ( v min ) is arranged , as already mentioned above , at the end of the expiration circuit , said valve offering an adjustable resistance to the outflow of gas in correspondence to the opening and closing of the expiration conduit controlled by said solenoid valve 12 , thus allowing the end expiration pressure to be finely adjusted ( fig3 ). the transducer continuously detects the instantaneous pressure in the ventilation circuit so supplying the signal to the control electronic system which also provides the processing of data and their visualization on the video 11 . a clear vision of the outer structure of the unitary system consisting of the pulmotor with electronic control of the image can be obtained by observing fig4 and 5 . with a detailed observation starting from the top and proceeding downwards , the presence can be remarked of the monitoring screen 11 which is connected to an electronic processing unit ( not shown ), of the control board 14 of the work operations ( which is shown in a more detailed way in fig6 ), of the printing unit 15 collected into a single structure resting on the frame 16 running on the wheels 17 . the rear view ( fig5 ) shows in addition as essential members the outlet 18 for feeding the gas mixture to the patient and the return 19 of the expiration gas from the patient , the connection 20 for the pressure detecting pipe , the rapid - type connections 21 and 22 respectively for oxygen and air and the pinchcock solenoid valve 23 which operates on the expiration conduit 8 and an identical spare solenoid valve 24 housed in a suitable groove , the valves v max and v min which are pointed out by the numerals 25 and 26 , the connection conduit 27 for the discharge which is endowed with the bottle 28 for the collection of the condensate . fig6 shows in its essential details the monitoring group with the screen 11 and the control board 14 . on said control board 14 , the presence can be observed from right to left first of all of the knobs for the regulation of the concentration of o 2 and of air in the feed mixture and respectively for the regulation of the flowrate of the o 2 and air mixture to the pulmotor , which knobs are pointed out by the numerals 29 and 30 and operate on calibrated housings in the range from 21 to 100 % as for the oxygen percentage and from 0 to 20 l / minute as regards the feed flowrate of the mixture . next the key control means 31 and 32 are provided for keying the keyed parameters consisting respectively of the inhalation and the expiration pressure , then the knobs 33 and 34 are provided for keying the minimum and maximum pressure values beyond which an alarm system intervenes and then the knobs 35 and 36 for keying respectively the times ti and te . a series of keys 37 - 44 in the central zone allows , in a succession from the left to the right the operations of &# 34 ; freezing &# 34 ; and of &# 34 ; thawing &# 34 ; of the video image to be performed , as well as the operations of changing the scale of representation , of turning the page of the file kit of the processor unit , of printing and of the timer . the screen 11 shows on the contrary an upper space bearing eight small boxes divided into two overlapping lines for the visualization of the following parameters : rate , ti , te , i / e , pip , mip - map , peep , and the ventilation time during employment of the pulmotor . in the lower part , the space is allowed on a diagram with pressures expressed as cm h 2 o on the ordinates and times in seconds as the abscissas , for the visualization of the pressure waves that show objectively in real time the values of the mip and map which are essential for controlling immediately the behavior of the ventilations when the working conditions are changed . in the next fig7 and 8 the representations are shown on an enlarged scale of various pressure waves , more particularly fig7 shows the pressure waveform 45 which appears in real time as a result of the continuous detection of the instantaneous pressure in the patient &# 39 ; s circuit and the transduction of such pressure into an electrical signal as a function of te and ti values as well as of pip and peep values all previously set forth . fig8 shows in a better way the meaning of the pressure waves 45 which allow , as already mentioned above , the values of mip and map to be estimated for a previously established difference between pip and peep and the respiratory rate fr . the dotted zone 46 shows with its total area the value of map + mip , the value of mip being given by the rectangular area between the axis of the abscissas and the parallel line corresponding to the peep value during the inhalation act . the present invention will be disclosed in the following example in its application to a particular clinical case of the hyaline membranes disease so as to make it clear the understanding of the characteristics of efficiency and reliability of the apparatus of the invention itself . a baby , the first of a pair of twins , the son of t . c . e . g . 35 weeks ; weight kg 2 ( 25 ° centile ); apgar 7 - 9 . about one hour after birth the new - born baby begins to show dispnoea and cyanosis crisis ; the baby is hospitalized in the new - born department where the baby arrives , aged six hours in very serious general conditions ; the clinical symptoms characterize a severe respiratory insufficiency . the baby is intubated and connected to the m . o . g ./ 2000 pulmotor working on the following parameters : ______________________________________ti = 0 , 4 sec fio . sub . 2 = 1te = 0 , 6 sec pip = 20 cmh . sub . 2 ofr = 60 / min peep = 3 - 4 cmh . sub . 2 o______________________________________ after improvement of short duration of the clinical conditions , such conditions begin to get worse and a pao 2 higher than 50 mmhg cannot be obtained even with a pip increase from 20 to 28 cmh 2 o to increase the volume flow ; moreover , the baby looks very restless and clearly wrestling with the pulmotor . when the baby is aged 15 hours the decision is made of treating the patient with curare to warrant a good adaptation to the pulmotor and to modify the parameters of latter in an attempt at improving ventilation . in the following disclosure reference is made to the further fig9 - 16 wherein the pressures on the ordinates are reported as cmh 2 o and times in seconds are reported as the abscissas . fig9 shows the print out obtained in real time of the parameters of the pulmotor and of the pressure waveform detected in the ventilation circuit shortly after the treatment of the baby with curare and the change of parameters . the following considerations can be obtained from the analysis of such figure : 1 ) the value of ti has been increased from 0 . 4 to 0 . 8 seconds ; on the contrary the value of te is kept unchanged ; thus the ratio i / e is inverted . the employment of a long ti is made optimal by the treatment with curare and it allows the realization to be obtained of a pressure wave of the square type , i . e . the pressure increase rate ( stemming from the value of the flowrate ) is of such a value as to allow the desired pip of 28 cm h 2 o to be rapidly reached and then to be kept for the remaining part of ti ( the plateau or inhalation pause ). the small pressure oscillations detectable above all during the inhalation pause can be referred to the presence of the condensate in the circuit . 2 ) the value which is best correlated singly with the oxygenation degree , above all in the hyaline membranes disease is the mip that is determined by the integration of the three parameters involved in the formation of the pressure wave , i . e . ti , flowrate ( or flowrate from which the waveform stems ) and pip ( that determines the value of vt ( fig1 ). the increase in ti and the inhalation pause ( the square waveform ) with an increase in the mip , cause the oxygenation to be improved , first of all because in that way the diffusion of o 2 at the alveolar level as well as a more uniform distribution of the gas among zones having different compliances ( a compliance difference implies different times of alveolar filling , i . e ., both &# 34 ; rapid &# 34 ; and &# 34 ; slow &# 34 ; alveoli exist ) are both favored ; thus the formation of atelectasias is contrasted , with a consequent improvement of the v / q ratio . on the contrary , the use of a rapid ti with triangular waveforms can cause the ventilation mainly of the alveoli which ar already expanded and the increase of pip beyond the limit which is necessary to assure a good expansion , causes the risk of hyperdistension and breaking . finally it is to be remarked that the increment of pip in a waveform of such a type will cause a low increase in mip , to the contrary of what occurs with a square - type wave and with a long ti . 3 ) the analysis of gas ( fig9 ) which was carried out shortly after such changes , shows a good vetilation ; the value of the fr is sufficient to warrant an adequate elimination of co 2 and then any change in te is useless . in the next ten hours ( fig1 ) it was possible to decrease gradually the value of fio 2 down to the value of 0 . 6 ; the other parameters were left unchanged except for the value of pip that was lowered to 25 cmh 2 o . the decrease in the o 2 percentage to warrant a good oxygenation is an index of gradual improvement in the pulmonary pathology , which is to be followed by a similarly gradual decrease in the insufflation pressures employed ( pip and mip ). it is to be remarked in fig1 that the absence of condensate water from ventilation circuit ( or of secretions from the tracheal cannula ) allows a graphic image to be obtained which is free from oscillations . the clinical conditions of the baby continue to improve and when the baby is aged 40 hours the fio 2 has decreased down to 0 . 4 ( fig1 ). from the analysis of fig1 the following comments can be made : 1 ) the pip reduction from 25 to 18 cmh 2 o is correct , the need being considered for a less percentage of the o 2 inhaled ; 2 ) the ti value is too long ; the operator in order to key a i / e ratio of 1 / 1 , i . e . in order to make such ti more physiological and in order to decrease simultaneously the value of the fr in order to make the paco 2 to increase and then to start the removal of curare , has keyed a ti / te of 1 sec / 1 sec . while this philosophy is correct for te , it is definitely uncorrect as regards ti . indeed , the correct procedure would have been that of reducing ti with respect to the value previously employed ( 0 . 8 sec ) and to modify the waveform so as to make the same more triangular ( a lower flowrate so that the pip is reached about at the end of ti ). such mistake shows that it is conceptually erroneous to consider the i / e ratio as a basic parameter for ventilation ; indeed , it is exclusively a datum that stems from the waveform type employed for realizing an optimal oxygenation ( mip ) and from the time te needed for obtaining a value of fr which is adequate for the elimination of co 2 . indeed , fig1 shows that the fr is equal to the preceding value , but the duration of ti and of te ( and therefor the ratio i / e ) has been much changed ; moreover , a comparison of the waveform with that of fig1 shows that a decrease has been obtained both of the mip and of the map , the first one through the reduction of ti and of pip , the second one above all through the increase in the te and the reduction in peep . finally , it is possible to observe during time te the occurrence of small pressure oscillations which are due to the recovery of the patient &# 39 ; s spontaneous breathing . fig1 and 15 show that the value of fr is further decreased under control of the pao 2 , as the spontaneous breathing acts become more and more valid and regular . it is to be emphasized that in the waveforms linked to the spontaneous activity of the patient , the value of the cpap is to be read at the top of the pressure wave , to the contrary of what occurs during the ippv ; in the latter instance indeed the breathing dynamics in inverted . the patient has been finally placed in a single continuous flow ( fig1 ) and then disintubated and placed in cpap + 3 cmh 2 o with a cannula through the nostril . the present invention has been disclosed with particular reference to some specific embodiments of the same but it is to be understood that modifications and changes can be introduced in the same without departing from the spirit and scope of the invention for which a priority right is claimed .
a constant flow and controlled - ventilation pulmotor responsive to the respiration pressure in the respiratory circuit of a patient in which the intervention of a processor causes visually observable information to be presented to the operator to allow immediate control of mechanical ventilation and the adaptation of same to the clinical requirements of the patient . first , second and third desired pressure , time and flow rate parameters are set by a control board . a maximum pressure - responsive valve is responsive to the first pressure , time , and flow rate parameters , a minimum pressure - responsive valve is responsive to the second pressure , time , and flow rate parameters , and a solenoid valve is responsive to third pressure , time , and flow rate parameters . a transducer continuously detects in real time the value of the instantaneous pressure in the respiratory circuit of the patent and supplies an electrical signal indicative thereof to the processor . the processor processes the signals from the transducer and the control board and respectively visualizes them on a video display as breathing waveforms and as numerals representative of the first , second , and third sets of parameters .