ASV(Adaptive Support Ventilation)

1. The concept and the purpose of the ASV

The ASV measures the pulmonary mechanics of the patient every breathing by the mode of the ventilation of the new concept to have been loaded into Hamilton Inc. Galileo and fixes an ideal air changes per hour, and it removes a goal expired volume per minute next in this and fixes a goal taking air quantity of ventilation. It has a purpose of providing breathing work volume to be least and the compulsion to be least for all the patients smoothly regardless of the size of the ventilation capacity. As the theoretical backbone, the type (mentioning later in the place of the control-theory) of Otis plays an important role. Breathing work volume of the patient fixes the air changes per hour which becomes the least by this type but the technique to replenish the number of times of the difference between the goal air changes per hour and voluntary air changes per hour by the active-ventilation by SIMV as the means which is adaptable to the patient in the goal air changes per hour is adopted. The moreover, that the spontaneous-respiration is PSV in the goal taking air quantity of ventilation to be adaptable active-ventilation It achieves quantity ventilation as the pressure ventilation method because it ventilates in PCV but it does PSV pressure (Psupport) or PCV pressure (Pcontrol) in the self-regulation (like AutoFlow of Evita4) based on the compliance to have won in the future ventilation to become a target value.

2. The component of the ASV

1) The ideal weight

The ideal weight is not the actual weight of the patient and means the true weight of the patient. The automatically goal expired volume per minute, the respiratory tract dead-space when entering an ideal weight and then when entering, based on it, a parameter with control is automatically set. Therefore, the setting of an ideal weight is an important factor and is a easy-to-understand index. However, in the internal process, it decides a goal expired volume per minute only based on the ideal weight. It will be rational to prepare beforehand the initial setting screen which can choose the option which sets a goal expired volume per minute straight if it does it, too.

2) The % expired volume per minute (%MV)

This setting plays a straight role to control a taking air quantity of ventilation. It influences the index which prescribes the minimum of the goal air changes per hour as well as it, too. When the ventilation capacity of the patient is kept, even if it decreases %MV, the air changes per hour doesn't decrease. When not kept, air changes per hour (f-target), too, rather declines when decreasing %MV.

3) The ideal air changes per hour

At the ASV, it fixes an ideal air changes per hour based on the type of Otis. As for the type of Otis, breathing work volume is the type which fixes the theoretical air changes per hour which becomes the least but to say that it is the best air changes per hour isn't always right on being clinical even if the dynamics ideally can be consented to.

4) The type of Radford

It is the type of Radford that, because the difficulty with the boiling which measures the respiratory tract dead-space directly accompanies, it seeks, being more statistical than the ideal weight. Because there are few rates which the dead-space accounts for in the type of Otis, generally, it thinks that the error doesn't influence too much.

3. The control system of the ASV

1) The controlling mechanism

It is only MPU control system.

2) The control-theory (Figure ; Air changes per hour and breathing work volume)

The theoretical root of the ASV is in the type of Otis which fixes the air changes per hour which makes breathing work volume the least. Breathing work volume is a summation between the elasticity work (decided at the lung and in the thoracic-cage-compliance and so on) and the fastness work (decided in the airway resistance and so on). The air changes per hour that this becomes the least becomes goal air changes per hour (f-target). It is the type of the following Otis that made this figure a type of the number : A.B. Otis, W. O. Fenn, and H. Rahn, "Mechanics of breathing in man", J Appl Physiol, vol. 2, pp. It is 592-607, 1950.

(Figure ; Type of Otis)

It estimates VD in 2.2ml/kg body weight. However, to fix f-target, RCe is undecided. It wins the data of TI, TE, Total Rate, VTinsp., RCexp, V/P(dynamic compliance) in the ASV by the test ventilation by PCV with five times. TI is measurement intake time, TE is measurement expiration time and Total Rate is voluntary air changes per hour and the one of the active-ventilation number of times. At the summation, total air changes per hour, VTinsp. are an intake taking air quantity of ventilation, RCe is expiratory time constant and is the one to have divided an expiration taking air quantity of ventilation by the peak expiration gas flow rate, the one that V/P divided an intake taking air quantity of ventilation by the peak airway pressure. f-target can be computed when substituting Total Rate for f and an actual measurement in the future ventilation is substituted by the other item, too. Because the % value to the setting expired volume per minute (being 0.2LPM/kg at the infant who decides in 0.1LPM/kg ideal body weight) is %MV, %MV/f-target becomes VT-target. It becomes TI=60/f-target-TE when using TE=3*RCe. The following ventilating-pressure (Pcontrol, Psupport) is decided when using VT-target and V/P. It does the following ventilation in this way and moreover it gets the data of TI, TE, Total Rate, VTinsp., RCexp, V/P. It provides best ventilation in repeating such a process every breathing. The normal-range is provided for these parameters and when deviating, it repeats recalculation until the other parameter fits in using the Limit value.

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3) The way of achieving an air changes per hour

Rational seemed seemingly the idea which makes up the lack of the spontaneous-respiration number of times with the SIMV number of times simply of it However, SIMV is not the ventilation mode to add to the number of the spontaneous-respirations and to give the number of the active-ventilations. Because it is the ventilation mode to give an active-ventilation (by) synchronizing with the part of the spontaneous-respiration and (adding), total air changes per hour is equal to the spontaneous-respiration number of times in case of the spontaneous-respiration number of times >SIMV number of times and becomes the SIMV number of times in case of the spontaneous-respiration number of times <SIMV number of times. Therefore, in the way of replenishing a shortage with the spontaneous-respiration number of times in SIMV with the number of times, actual total air changes per hour doesn't increase immediately.

It attempts to simulate this below. f-term means a goal air changes per hour. f-trigger is the true spontaneous-respiration number of times of the patient with the meaning which is essential, meaning all air changes per hour where there was a trigger regardless of the spontaneous-respiration and the active-ventilation. f-SIMV is the setting SIMV number of times. SIMV defines only the spontaneous-respiration which doesn't weight as being f-spont. in the active-ventilation. In the active-ventilation, a weighting spontaneous-respiration is measured by f-control. f total is total air changes per hour which is ‘—‹Ced by the resuscitator. f total is the summation of s-control with f-spont.. It makes ‡@ initial condition first, it makes f-SIMV 6 by air changes per hour 12 and it makes f-spont and f-control 6 respectively. It is doing all triggers by the spontaneous-respiration. It makes a spontaneous-respiration to have decreased in ‡A and makes f-trigger to have decreased to 10. Because f-SIMV is as 6, f-control becomes 6. As a result, f-spont becomes 4 because it is f-trigger-f-control. f-total becomes 10. Well in ‡B, according to the computation 12-4=8 of f-term-f-spont, f-SIMV is increased to 8 by f-SIMV. In ‡C, f-SIMV becomes 10 more, in ‡D, it becomes 12 and gradually, with this step, f total recovers in 12. In ‡E, f-term makes to have increased to 15. f total, too, becomes 15 immediately because f-SIMV increases now to 15 at a breath. Next, it makes the condition that f-trigger was increased from the condition of ‡@ to 15 ‡F. f-SIMV decreases in order with ‡G‡H and the active-ventilation number of times decreases but f-total is as 15 which is the same as f-trigger. This time, it assumes condition ‡I that f-term was decreased from the condition of ‡@ to 10. In this case, in order, f-SIMV decreases with ‡J‡K. In ‡L, the condition that f-trigger was decreased from the condition of ‡K is shown. ‡M‡N and f-SIMV increase and finally, f total recovers in 10. Taking time for f total to recover when f-trigger decreases to see and to understand these results On the other hand, the sudden increase of f-term is reflected in f total at once. When there are more f-trigger than f-term, the value of f-trigger is reflected in f-total just as it is and f-term is never manifested by the result. However, it works to decrease f-SIMV. When the rapid decrease of f-trigger occurs like ‡L, the recovery of f total takes quite time.

In the actual processing, generally, because it does the processing which equalizes tens of seconds of the pasts, there is a time lag in equal to or more than tens of seconds in the measurement of f-spont "NADO" by the time the value reflects as the decrease of f-spont after the sudden anaerosis occurs. Because the f-SIMV process of the increase is necessary for about 4 breathing on it, by the time f total recovers finally, the time lag in about 60 seconds occurs. When preventing the rapid decrease of the air changes per hour by the occurrence of the anaerosis The processing which makes f-SIMV compulsorily the value which is the same as f-term at the same time as the , anaerosis occurs seems to be necessary but there is not a comment to make such compulsion processing current.

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f To solve delay to the total revision, the method the SIMV number of times of which is the number of times which is the same as the goal air changes per hour from the beginning, too, is thought of. In this method, a shortage with the spontaneous-respiration number of times is immediately replenished by the active-ventilation which is SIMV. However, until the trigger number of times (this isn't always equal to voluntary air changes per hour) of the patient exceeds a goal air changes per hour, all ventilation has been given in ASSIST/CONTROL. Incidentally, the expired volume per minute should become a target value. When the trigger number of times exceeds a goal air changes per hour, PSV is stored of exceeding only for the number of times. The expired volume per minute should be added to the goal expired volume per minute only in the minute of the PSV ventilation. In this method, because an active-ventilation is predominantly given, the active-ventilation can cause a provided evil unnecessarily. Therefore, as the compulsion processing of an anaerosis, this method is desirable, but it is in the use difficulty in usual processing and it is possible to say "TO".

4. The advantage and the fault of the ASV

1) The compulsion of the air changes per hour

The former forces the minimum (lower limit) of the expired volume per minute whereas the point to compel to do both of the air changes per hour and the expired volume per minute minimums the biggest difference of EMMV and the ASV has latter. The algorithm to compel a patient to do "the theoretically right? air changes per hour" at least and that breathing work volume becomes doesn't cause "the shallow tachypn ea" which EMMV which set PSV pressure improperly low could admit. Also, it doesn't induce phenomena such as "deep" and "few air changeses per hour" to admit often in SIMV(AutoFlow), too. However, will "the theoretically right? air changes per hour" be the air changes per hour which the patient wants truly? The ventilation capacity of the patient doesn't become a problem in the weak step and this thing brings about a rather desirable result. However, if the ventilation capacity is above being certain degree of, it is always the point to be made to compel to do "the theoretically right? air changes per hour" and there is possibility that Fighting occurs. ASV however, it is possible to be permissible where by the degree of freedom of the patient to the compulsion and the medical practice person has the fault which can not be optionally set.

2) The setting of %MV

Even if the essential purpose which controls %MV is the same ideal weight of the simile with the disease of the patient, the expired volume per minute to require is compatible to the different clinical condition. For example, in the acute period of the serious ambustion patient, at the time of the minute, the required amount of the ventilation is rising. However, there is a side in addition to the feature for the medical practice person to ease the minimum of the compulsion expired volume per minute which eases the evil of forcing above-mentioned "the theoretically right? air changes per hour" actually, too, in this. Even if it sets the minimum of the compulsion expired volume per minute to rather many, on the surface which is called the synchronism of the patient ventilation and the mechanical ventilation, empirically few evils occur and empirically, Fighting because of this, too, is hardly admitted. Well, it is the one of %MV for (there to be a way of changing the set value of the ideal weight) in the ASV why. f-target, too, falls when lowering the target value of the MV according to the type of Otis if saying whether or not setting is laid down and the compulsion number of times of "the theoretically right? air changes per hour", too, is the thing to aim at the decreasing effect. Theoretically, that the minimum of the goal expired volume per minute and the minimum of the goal air changes per hour can be set independent is right but when considering indefiniteness of the complexity of the setting and the index for the setting, it may be rational to finish these setting by one setting of %MV. However, when the ventilation capacity of the patient is kept above being certain degree of, because the expired volume per minute and the air changes per hour of the patient don't undergo influence too much even if it makes %MV decline, the effect which lowers a minimum with the active-ventilation number of times can look forward to it hardly. Because the possibility that need which lowers the number of the active-ventilations to the patient who has a ventilation capacity occurs is high on being clinical, this is big contradiction. This technique will become right in the clarifying with the clinical-evaluation in the future.

3) The followingness to the change of the ventilation capacity

The phenomenon that a hyperventilation and a hypoventilation are periodically repeated in EMMV is often observed but a measure to the anaerosis behind the general hyperventilation is done to EMMV. ASV however, of course, such a phenomenon can happen. However, at the ASV on the principle, the air changes per hour doesn't recover immediately to the sudden anaerosis like being above-mentioned. The anaerosis back-up feature is standing by as this measure but this is the last means persistently. 60 s of hypoventilation ( of the limit which doesn't depend on the anaerosis back-up if saying paradoxically / 15 s=4 bpm) can happen. This is the defect of the ASV in the present.

As for the followingness to the change of the ventilation capacity of the patient at the normal condition, the performance to have compared with EMMV specifically will become in the clarifying with the evaluation of the future.

4)Auto PEEP

Because RCe plays a big role in the index which fixes an ideal air changes per hour, it is difficult for Auto PEEP to occur. There is not a comparative dater with PAV.

5)sink or swim

The patient is the ventilation mood as it is possible to hurry in a sense which can force into the spontaneous-respiration to avoid an active-ventilation as EMMV which doesn't use PSV "can swim, ! "MONAKUBA" sinks and" expressed, saying "!". Therefore, the evil which does a shallow tachypn ea is often admitted and there is history which wasn't clinically evaluated. Because it has more supplementary algorithm at the ASV, there is not such an evil. However, by lowering %MV, "the overprotection can not be forever left by passing" evil can be excluded.

6) The application range

The ventilation capacity is the mode which can be adaptable to all the patients including the changing patient between the existence or non-existence of the ventilation capacity and also the short time. By the effect however, that the patient of COPD promotes a spontaneous-respiration of PEEP in average airway pressure's declining and being consequent It brings about an effect like lowering. PaO2"NO"’ቺ"WO"�µ"KU"‰Â”\�«"WO"žX—J"SURU"•K—v"GAARU"("KAMOSIRENAI")�B

8) The characteristic of the ventilation

Few evils by the positive pressure ventilation occur because it is the pressure ventilation mode which is the same as AutoFlow. Therefore, there is possibility to reduce the complications of the positive pressure type resuscitator.