EMMV(Extented Mandatory Minute Volume ventilation)
1. The concept and the purpose (Figure ; EMMV)
Hewlet contrived MMV in 1977, and used and created Bird ventilator. (Figure ; First MMV equipment (Hewlet)) It breathes freely, but in gas in the reservoir, if a set expired volume per minute isn't achieved, it is switched on and an active-ventilation corresponding to the shortage is begun by the spontaneous-respiration. It is in the fault that this active-ventilation doesn't synchronize with the spontaneous-respiration. If being voluntary air quantity of ventilation above the expired volume per minute which a breathing effort was sufficiently set to, an active-ventilation isn't supplied. This mechanism is the Extended MMV(EMMV) method which can be intake above the expired volume per minute which was mechanically composed in the beginning, but was composed of the electrical treating circuit which applied all MPU (Micro Processor Unit) at the marketed product and was set. Also, an active-ventilation synchronizes with the spontaneous-respiration and is given except the method of the Engstrom Inc.. In CPU-1 and Erica, Evita 等, PSV+EMMV is possible.
(Reference 5) MMV and EMMV
To distinguish from Minimum Minute Ventilation which uses the abbreviation of the same MMV, the this manual expresses Mandatory Minute Ventilation with EMMV.
2. The component
The (1) free ventilation aspect (or PSV) is in the basic condition and EMMV becomes (2) active-ventilation aspect in the expired volume per minute which a spontaneous-respiration was set to only when not achieved. An active-ventilation aspect is done in CMV or SIMV.
3. The control system
1) The controlling mechanism
This includes two of the (1) mechanical method (2)MPU control systems. All models which were marketed so far are MPU control system.
2) The operation form
It contrives the form which differs in each manufacturer.
a) The Engstrom method (The CMV addition method)
If the expired volume per minute (the intake quantity) of voluntary becomes below the set value in Erica and Elvira, it switches over to the CMV mode from the spontaneous-respiration mode. It returns to the original spontaneous-respiration mode when the expired volume per minute of the goal is achieved.
(2) The Drager method (The SIMV addition method)
SIMV mode is inserted if the expired volume per minute (the intake quantity) of voluntary becomes below the set value in Evita.
(3) The Ohmeda method (The SIMV number of times control mode)
EMMV of CPU-1 is not an original control system, and compares the actual measurement and the set value of the expiration expired volume per minute every 24 seconds, and it fluctuates by 12.5% or 25% and tries to stabilize an expired volume per minute in the SIMV number of times according to this ratio. However, the intention "DOURI" boiling expiration expired volume per minute doesn't always increase if increasing the SIMV number of times. Therefore, the Back Up number of times which is called Security value, preparing for the status which can not maintain an expiration expired volume per minute is prepared.
4. The modification element
1) As much as the measuring section of the expired volume per minute
The expired volume per minute is an important control index and the control mistake is fatal. Measurement (Ohmeha,Bear) of the side of the expiration of (Engstrom,Drager)(2) of the measurement of the side of (1) intake is chosen according to the measurement accuracy of the expired volume per minute measuring system. It is desirable to measure in the side of the expiration when considering the circuit leak of 送気 gas but the rapidity which is high with the operation of the control system which the delay which is temporal more than the measurement on the side of intake occurs to is sought. Generally, at the air quantity of ventilation measuring equipment of the hot wire type, it isn't used as the EMMV control-information because the certainty is scarce. (Exceptions CPU-1, Bear-1000)
(2) The measurement time of the expired volume per minute
It is an active-ventilation even if the expired volume per minute declines and the time not to compensate for becomes long when the measurement interval is long. On the other hand, the interval can not operate smoothly when too short. CPU-1 measures 24 seconds of the pasts every 24 seconds. Bear-5 measures 20 seconds of the pasts every 10 seconds of triggers. Evita is totaling an air quantity of ventilation in the past by the measurement at any time, weighting by filtering processing. Specifically, 20 seconds of the pasts become the processing which was thought much of. Details aren't made public.
(3) The processing of an anaerosis behind the hyperventilation
It becomes a hyperventilation in the active-ventilation of EMMV and the anaerosis sometimes continues after that. There are many models to be limiting anaerosis time behind the hyperventilation to to avoid the big change of the expired volume per minute by this.
(1) It is equipped with Time limit function which sends an active-ventilation within 3-10 seconds in Erica, Elvira. In the permissible time, it is the set value of the taking air quantity of ventilation and the expired volume per minute and it is decided but details aren't published.
(2) In CPU-1, the anaerosis back-up feature (15 seconds) which is called Apnea monitoring supports this.
(3) In Evita, SIMV cycle is compulsorily begun by 15 seconds of anaeroses. Also, there is a characteristic to be quick in response originally according to above-mentioned filtering processing.
(4) The anaerosis time doesn't become long because Bear-5 is SIMV+EMMV originally. Also, it is 20 seconds and SIMV cycle with the Back Up number of times is begun if the degree of the hyperventilation is big within 10 seconds in the general ventilation on the mechanism.
5. The advantage and the fault
EMMV is the mode to have been contrived to decrease the active-ventilation number of times of IMV possibly and 及. Then, it was interpreted as the mechanism which proceeds with the weaning automatically, but actually, to be maintained by "the shallow tachypn ea" tended and it was not an appropriate mode. However, however, because the parameter which controls EMMV is only an expired volume per minute, when the respiratory function improves and an appropriate expired volume per minute is gotten, when achieved by the remarkable intake effort, the active-ventilation has decreased in the same way and becomes disadvantageous to the latter.
After EMMV development, PSV was contrived, and Engstrom and Drager combined with PSV and practicalized breathing form, EMMV+PSV. In to use PSV, "the shallow tachypn ea" by EMMV was improved, but the control system and the rhythm of the patient didn't still suit and the expired volume per minute tended to change periodically. As for EMMV, that that that the operator can not set the range by which free breathing of the patient is permissible "TAME" or to have been forced away to the popularization of PSV "TAME" got proper evaluation sang declined. However, the possibility of EMMV was re-recognized by Bear5 of the Bear Inc. and EMMV in Bear1000 and voluntary air quantity of ventilation was flexibly evaluated as the ventilation mode to be adaptable in the appropriate active-ventilation to the changing patient. Moreover, when Evita of the Drager Inc. uses AutoFlow for the active-ventilation, it is the EMMV one of filtering algorithm. Along with the excellence, the percentage of completion became high for EMMV(AutoFlow)+PSV not to stay in "the security apparatus which assists PSV" and "a kind of the back-up ventilation by the automatic-reset type" and to be able to use as the standard ventilation mode. The evil by the disparity of the rhythm of the boiling and attended trigger windows and patient breathing such as SIMV became not to have been and to have been able to make an active-ventilation be adaptable to the patient very smoothly when using EMMV.