VS,PRVC(Volume Support,Pressure Regulated Volume Control)
1. The concept and the purpose (Figure ; Volume Support, figure ; Presuure Regulated Volume Control)
Being "DURE", too, was proposed in Servo-300 of Siemens. Servo i however, it is possible to have an option.
1)Volume support(VS)
VS is Hamilton-MMV(H-MMV) and similar operation form. That is, based on the compliance of the measured future ventilation, the necessary taking air quantity of ventilation chooses gotten PSV pressure automatically. It is possible to say that the parameter to change PSV pressure to is different and in the point to stabilize the quantity to have set a taking air quantity of ventilation to, the ventilation law based on the concept to be the same comes out about VS and H-MMV.
When the spontaneous-respiration stops, VS is equipped with the back-up mechanism (training Automode, an option severely) which switches over to Pressure Regulated Volume Control(PRVC) automatically.
2)Pressure Regulated Volume Control(PRVC)
PRVC is the form to have made Pressure Control Ventilation (PCV) develop into and is the mode to set PCV pressure automatically for a constant taking air quantity of ventilation to be gotten based on the compliance of the future ventilation which was measured like VS. PRVC is one of the variations of the ] type active-ventilation. PRVC and AutoFlow are the concept to be the same almost but Servo300 can use them only as A/C. SIMV+PSV however, Servo i, and Evita4, Evita XL can use.
(Reference 8) PCV and PRVC
The Siemens Inc. was recommending PCV/IRV. As the means that the air quantity of ventilation cancels a changing fault in the process of the clinical application, PRVC was developed. For a pair of PCV to include PSV, VS was contrived as a pair of PRVC. If saying theoretically, as for PRVC, it was easy for PS-VC and the one to have been expressing to understand PC-VC and VS (VC=Volume Control).
2. The component
It is the component which is the same as PSV, PCV.
3. The control system
1) The controlling mechanism
It is done in MPU.
2) The operation theory
The first ventilation is 5cmH.2It measures a conduct compliance in the test ventilation of the O. It ventilates three times at 75% of the pressure which is necessary to maintain the taking air quantity of ventilation of the goal from this value. After that, a ventilating-pressure is automatically set according to the compliance value in the eve every piece of breathing. The ventilating-pressure is Upper Pressure Limit-5cmH from the PEEP level.2It changes in the O range but taking change is 3cmH.2It has been suppressed below the O. If the gas volume in case of intake becomes 175% of the set value in VS, the intake ends compulsorily.
4. The modification element
1) The processing when a trigger isn't gotten
In VS, the air changes per hour depends on the patient. If more, there is not a problem but if there are spontaneous-respirations than the setting breathing rates, when little, it sets the taking air quantity of ventilation of the goal newly inside the inside to maintain an expired volume per minute based on the value of the measurement breathing rate. The trigger mistake causes the abnormal ventilation.
2) The measurement method of the compliance
It is computing by 1 piece of breathing of the test ventilation and the future. The extraordinary influence of the measure ends by 1 piece of breathing.
3) The way of ventilating a test
It is done to measure a compliance but this sometimes becomes West ventilation, too.
4) The standard, the cancellation standard which switches over from VS to PRVC
In the model not to be equipped with Automode, only the anaerosis alarm lets me know switchover. It doesn't do an automatic-reset. When an anaerosis is caused by the model to have been equipped with Automode, switchover from VS to PRVC is automatically done. It returns to VS automatically when a spontaneous-respiration is restored.
5) The minimum air quantity of ventilation of the active-ventilation
Currently, it isn't possible to set.
5. The advantage and the fault
(1) PRVC
Because it puts on in the lower place compared with the other ventilation law, there are few barotraumas, they are excellent about the oxygenation ability, there is an advantage that few influences over the circulation occur, and so on, and a maximum airway pressure is used for IRV by PCV. However, it is in the fault that the taking air quantity of ventilation isn't stable. It is PRVC that canceled this fault and is in the defect in being the form that the spontaneous-respiration assumed a weak (not resisting an active-ventilation) condition with PCV.
(2) VS
The degree of freedom of the patient is substantially limited because it is in the advantage but a taking air quantity of ventilation is forced in the stabilization of the air quantity of ventilation compared with PSV about VS. It doesn't become EMMV if comparing to the MMV method.
(3) As VS+PRVC
The control object is the same as conventional active-ventilation (Volume control) and can place both methods in the middle of PSV and the active-ventilation. However, the taking air quantity of ventilation is mechanically forced and doesn't become the liberty of the patient. Therefore, the ventilation capacity doesn't become adaptable about the patient above being certain degree of. However, also, when more, when the patient spends a great effort and increases a taking air quantity of ventilation, the ventilating-pressure falls more than necessary and when there are more taking air quantities of ventilation which the patient desires than the set values, when spends and increases, when the worst, there is danger to have fallen to the PEEP level.
4) The control thought
In the viewpoint on the side of the healer which was called the improvement of the oxygenation efficiency and the ventilation efficiency in VS, PRVC It is based and a control is done, but it lacks the viewpoint in the comfort of the patients' side which is seen by AMV, i.e. "the balance of the best free ventilation and the active-ventilation for the patient" and it is the control thought which isn't made in North Europe.