SERVO-i VENTILATOR GRAPHICS

SERVO-i VENTILATOR GRAPHICS
4/17/2017 SERVO-i VENTILATOR GRAPHICS Christine Pålsson 2 2

INTRODUCTION © MAQUET 3 MCV REVA 3

MEDIASTINUM AND CHEST WALL
INTRODUCTION MEDIASTINUM AND CHEST WALL Also be aware of what surrounds the lungs: the mediastinum, the muscles of respiration and the chest wall. Abnormalities in these structures may impact the lung funtion and hence ventilator graphics. © MAQUET 4 MCV REVA 4

INTRODUCTION AIRWAYS AND ALVEOLI
As you are looking at ventilator graphics, try and visulize a flow of air from the ventilator moving through the upper airways and down to the alveoli and the exhalation process as it travels back through to the upper airways. In volume-controlled ventilation for instance, as the flow moves down the large airways to the smaller ones the pressure will understandably increases as it moves to the smaller airways. © MAQUET 5 MCV REVA 5

KEEP IN MIND WHEN EVALUATING VENTILATOR GRAPHICS
INTRODUCTION KEEP IN MIND WHEN EVALUATING VENTILATOR GRAPHICS What type of ventilation is the patient receiving? What are you looking at? Does it make sense? Keep in mind the following when evaluating ventilator graphics: What type of ventilation is the patient receiving? Types of ventilation such as pressure and volume or controlled and spontaneous modes. What are you looking at? A graphic which may be normal looking in one breath type may be abnormal in another type. It is important to remember which type the patient is receiving at all times. Does what you see make sense considering the settings and the patient‘s condition? © MAQUET 6 MCV REVA 6

TYPES OF VENTILATOR GRAPHICS
INTRODUCTION TYPES OF VENTILATOR GRAPHICS Scalars: Pressure - Time Flow - Time Volume - Time Loops: Volume - Pressure Flow - Volume There are two types of ventilator graphics: Scalars and Loops. Scalars show the relationship of pressure and time, flow and time, and volume and time. Loops show the relationship of volume and pressure as well as flow and volume. © MAQUET 7 MCV REVA 7

VOLUME VS. PRESSURE VENTILATION - SCALARS
INTRODUCTION Determine whether the waveform you are examining belongs to a constant flow mode or a decelerating flow mode. That way you will know how the waveform is expected to behave. Then you can compare the expectation to the actual behavior as you read from left to right. VOLUME VS. PRESSURE VENTILATION - SCALARS You read a waveform like you read a sentence…from left to right. By the time you get to the end, you should have a complete thought, just like reading a sentence. Volume Breath Pressure Breath PAW PAW There are two types of ventilation: volume and pressure. The graphs on the left are the pressure and flow scales in volume ventilation. In volume ventilation the clinician sets a tidal volume and an inspiratory time (which gives the patient a set constant peak flow). As the constant flow is being delivered, the pressure ascends until the set volume is delivered. During volume ventilation the pressure-time scalar should look like a shark’s fin. The graphs on the right are the pressure and flow scales in pressure ventilation. In pressure ventilation you set a pressure. Pressure ventilation can either be pressure control or pressure support. In order for the pressure to almost immediately reach the set parameter, the initial peak flow is very fast. The flow is descending and variable, controlled by the patient’s demands, lung compliance and airway resistance. The pressure scale is square during the entire inspiratory phase. Flow Flow Time Time © MAQUET 8 MCV REVA 8

VOLUME VS. PRESSURE VENTILATION - LOOPS
INTRODUCTION VOLUME VS. PRESSURE VENTILATION - LOOPS Volume Breath Pressure Breath Loops show the relationship between two values. These are the two loops that the Servo i can display: Volume – Pressure and Flow – Volume Looking at the volume-pressure loop of the volume breath on the left, as inspiration begins the pressure rises as the volume increases. In the flow – volume loop below it, as inspiration begins the constant flow progresses as the volume increases. Notice how they look different in volume as compared to pressure breaths. Look at the Volume-Pressure loop in the pressure breath on the right. As inspiration begins, the pressure rises to the set pressure before much volume is delivered. As the pressure holds at the set level during inspiration the volume increases. Notice the difference betwen the inspiatory phase in both of the Flow- Volume loops. The constant flow is evident in the volume breath as compared to the decelerating inspiratory flow of the pressure breath. The expiratory phase in the both loops of both breath types are effected by the patient‘s lung condition. Visulize an imaginary slope like these on the volume – pressure loops. (click to have slope lines appear). This denotes lung compliance. The more horizontal the lines the lower the compliance. For instance, if the lung compliance decreases in volume ventilation it would take more pressure for the same volume. © MAQUET 9 MCV REVA 9

INTRODUCTION VOLUME VENTILATION Pressure Constant Flow
In volume ventilation the flow is constant. As the flow is delivered to the airways the pressure asends to a PIP as the set volume is reached. Constant Flow © MAQUET 10 MCV REVA 10

INTRODUCTION PRESSURE VENTILATION Pressure Decelerating Flow
In pressure ventilation the flow is desending and variable. As the flow is delivered to the airways the pressure increases to the set PIP. The returned volume will be dependent on the lung complience, airway resistance, intrinsic PEEP, the set pressure and the patient effort. Decelerating Flow © MAQUET 11 MCV REVA 11

INSPIRATION AND EXPIRATION
INTRODUCTION INSPIRATION AND EXPIRATION Inspiration ends Expiration ends Read waveforms one at a time. Don’t try to assimilate all three at once. Inspiration begins Expiration begins Identify the beginning and end of inspiration and the beginning and end of expiration. This is the Servo-i’s main screen. The mode in this example is Volume Control. These are the basic settings for that mode on the bottom of the screen. The measured patient values are on the right side of the screen vertically. The Servo-i always lays out the scalars on the main screen. The pressure-time, then the flow-time are always the top two scalars respectively. The third is the volume-time scalar. You can remove the volume-time scale if you choose. There can also be a fourth scalar on the bottom which could either be ETCO2 or EDI depending on whether or not these technologies are being utilized. We will touch on Edi later in this presentation. When looking at scalars, inspiratory begins here, inspiration ends as expiration begins and expiration ends here. Some would argue expiration ends just before the next inspiration begins. © MAQUET 12 MCV REVA 12

MODES OF VENTILATION © MAQUET 13 MCV REVA 13

VOLUME CONTROL SCALARS
MODES OF VENTILATION VOLUME CONTROL SCALARS Know what kind of waveform you’re reading and note the value to which the scale is set. As a review of the main screen, the waveform scalars are pressure – time, below that is flow-time and under that is volume-time. Notice on the pressure –time scale the inspiratory phase looks like a sharks fin. The pressure increases until the inspiratory time is reached. This peak pressure is known as the Ppeak. Looking now at the flow-time scale, the set constant flow is delivered. Looking now at the volume –time scale the delivered tidal volume goes in and then the return volume comes out. © MAQUET 14 MCV REVA 14

VOLUME CONTROL LOOPS AND SCALARS
MODES OF VENTILATION VOLUME CONTROL LOOPS AND SCALARS Loops can be added to the screen by pressing Loops in the Quick Access menu. Looking at the Volume-Pressure loop, as pressure increases as the volume increases. On the flow-volume loop, insiratory flow is constant and peak expiratory flow decelerates as expiration is completed. Notice on both loops they both are closed loops. This will be important to know when we compare these normal graphics to abnormal graphics later in the presentation. © MAQUET 15 MCV REVA 15

FLOW-ADAPTIVE VOLUME CONTROLLERTM
MODES OF VENTILATION FLOW-ADAPTIVE VOLUME CONTROLLERTM Volume controlled ventilation: If during a positive pressure breath, the patient makes an inspiratory effort, you may see a “dip” in the pressure curve. In the past, one of the problems with volume-controlled breaths was if the patient demanded more flow than the therapist set the patient would be flow starved. The Servo i has a feature called the Flow-Adaptive Volume Controller. With the Servo I, if the patient requests more flow than the set value by decreasing the airway pressure by 3 cmH2O during the inspiratory phase, the ventilator delivers as much extra flow as the patient requires. You can see on the pressure scale that this patient is decreasing his pressure which activates the contoller by delivering more flow as you can see on the flow scale. A waveform can change in appearance with a change in the patient’s compliance, resistance or effort. © MAQUET 16 MCV REVA 16

PRESSURE CONTROL SCALARS
MODES OF VENTILATION PRESSURE CONTROL SCALARS In pressure-controlled breaths breaths are either patient or time triggered. The pressure scale is square denoting a constant set pressure throughout the entire inspiratory phase. This is accomplished by the fast initial inspiratory peak flow which decelerates throughout inspiration per patient condition and demand. The volume will be variable as well. Looking at the volume scale, again delivered volume in and returned volume out. © MAQUET 17 MCV REVA 17

PRESSURE CONTROL LOOPS AND SCALARS
MODES OF VENTILATION PRESSURE CONTROL LOOPS AND SCALARS Looking at the Volume-Pressure loop, the pressure increases on inspiration before much volume is delivered . On the Flow-Volume loop, the inspiratory flow is decelerating after an intial fast peak flow. © MAQUET 18 MCV REVA 18

SIMV (PRESSURE) WITH PRESSURE SUPPORT SCALARS
MODES OF VENTILATION SIMV (PRESSURE) WITH PRESSURE SUPPORT SCALARS This graph is of SIMV with pressure breaths. The spontaneous breaths are pressure supported in this example. © MAQUET 19 MCV REVA 19

MODES OF VENTILATION PRVC START UP PROCESS
PRVC or Pressure Regulated Volume Control is a pressure control breath type. Other than the startup breath, graphically it looks exactly like pressure control with the square pressure scalar and the declerating variable inspiratory flow. PRVC differs from pressure control by the fact that the tidal volume is set instead of the pressure. The pressure control will increase or decrease by 1-3 cmH2O on a breath-by-breath basis attempting to maintain the set tidal volume. This graph shows the startup breath in PRVC. In order to get close to the required pressure quickly the vent initally delivers a volume breath with a Pplat. This Pplat is the starting pressure for the first pressure breath. © MAQUET 20 MCV REVA 20

PRVC IN USE: PATIENT‘S ADJUSTMENTS
MODES OF VENTILATION PRVC IN USE: PATIENT‘S ADJUSTMENTS In this example: the clinician has set a tidal volume at 400 ml. The first full breath is delivering the requested tidal volume. The second and third breaths are delivering higher volumes due to changes in the patient‘s lung compliance and/or airway resistance. In response to this increase in tidal volume, the pressure automatically decreases on a breath-by-breath basis attempting to keep up with the patient and delivering the set VT. © MAQUET 21 MCV REVA 21

PRESSURE SUPPORT SCALARS AND LOOPS
MODES OF VENTILATION PRESSURE SUPPORT SCALARS AND LOOPS Graphically pressure support ventilation looks like pressure control ventialtion. Presssure support breaths are like pressure control breaths except the breath is flow-cycled. Pressure control breaths are time-cycled. Let‘s look at how flow-cycling works on the Servo I. © MAQUET 22 MCV REVA 22

MODES OF VENTILATION FLOW-CYCLING Peak Inspiratory Flow 50% 25% Flow
Pressure Support and Volume Support both cycle from inspiration to expiration the same way: flow-cycling. In flow-cycling, the inspiratory phase of the breath cycles off into expiration when the variable flow decelerates to a certain percentage of the peak flow of the breath. Older ventilators have a set percentage. The Servo I has a parameter called Insp Cycle Off. This is that percentage. If the ICO is set at 50% the breath will cycle off when the inspiratory flow declerates to 50% of the peak flow. If the ICO is changed to 25% and everything remains constant the breath will not cycle off until the peak flow decelerates to 25% of the peak flow. Flow 50% 25% Time © MAQUET 23 MCV REVA 23

MODES OF VENTILATION INSPIRATORY CYCLE OFF 100%
In this example the ICO is set at 20%. When the inspiratory flow decelerates to 20% of the peak inspiratory flow the ventilator will cycle off into exhalation. © MAQUET 24 MCV REVA 24

MODES OF VENTILATION INSPIRATORY CYCLE OFF
In this graph, the ICO is set at 1%. The peak flow is 36 lpm. The ventilator will cycle from inspiration to expiration when the inspiratory flow decelerates to 1% or less than 1 lpm in this case. © MAQUET 25 MCV REVA 25

In this graph the ICO has been set at 50%. When the inspiratory flow decelerates to 50% of 36 lpm in this case, inspiration cycles off at 18 lpm. © MAQUET 26 MCV REVA 26

If you see a curious aberration on one waveform and you can’t account for it, look at the other waveforms at the same point in time to see if there is a cause and effect relationship. INSPIRATORY CYCLE OFF Graphics are necessary for properly setting ICO in pressure supported breaths. If the patient wants to exhale earlier than the % setting of the ICO is set, he can with pressure-cycling by raising the inspiratory pressure 3 cmH2O above the set PS level above PEEP, the breath will cycle from inspiration to expiration. It will be noticable on the pressure-time scalar by the spike at the end of the inspiration. This would suggest the ICO needs to be set at a higher %. Notice the Ti is shorter on the second breath with the spike than the previous breath. We will see another reason to increase the % of ICO when we look at leaks in a pressure suppported breath. Remember, the longer the Ti in a pressure support breath, the more volume is delivered. You may want to decrease the ICO to give the patient a longer breath. Look at the volume-time scalar in this gragh. The first breath has a longer Ti which results in a higher tidal volume than the shorter second breath. If during a positive pressure breath the patient tries to exhale against a closed exhalation valve, you may see a spike in the pressure curve. © MAQUET 27 MCV REVA 27

VOLUME SUPPORT SCALARS
MODES OF VENTILATION VOLUME SUPPORT SCALARS Volume Support is a mode much like PRVC. The clinician sets a tidal volume and the pressure support type breath increases or decreases its pressure to attempt an maintain the requested tidal volume. In this example the pressure support ramps up to maintain the set tidal volume of 400. All breaths are spontaneous as in Pressure Support. In PRVC it is a Pressure Control type breath meaning that the clinician sets an I time. © MAQUET 28 MCV REVA 28

INSPIRATORY RISE TIME © MAQUET 29 MCV REVA 29

Or, adjust the IRT for patient comfort without causing “flow hunger”.
INSPIRATORY RISE TIME Adjust Inspiratory Rise Time to satisfy the patient’s inspiratory demand without causing turbulent flow. Or, adjust the IRT for patient comfort without causing “flow hunger”. Inspiratory rise time or T insp.rise is the time taken to reach the peak inspiratory flow or pressure at the start of each breath. In this graphic of pressure contol the T insp. rise is set at 0 seconds. This means the the inital peak flow is very fast in order to reach the set pressure immediately. Depending on patient effort you could have a ringing at the beginning of the pressure breath. This may cause some discomfort and in some cases auto triggering. © MAQUET 30 MCV REVA 30

INSPIRATORY RISE TIME In this graph the T insp. rise is increased to 0.20 seconds. This lowers the inital peak flow which in turn (in pressure ventilation) delays the inital pressure rise, softening the breath, if you will. This may bring more comfort to the patient. © MAQUET 31 MCV REVA 31

LEAKS © MAQUET 32 MCV REVA 32

LEAKS LOOK AT VOLUME Volume - Time Scalar Volume - Pressure Loop
Flow - Volume Loop Leaks can be easily detected on graphics by looking for VOLUME. Of the three scalars and two loops that the Servo i displays, the following can be used to detect leaks: VOLUME-time scalar VOLUME-pressure loop Flow-VOLUME loop © MAQUET 33 MCV REVA 33

Volume Time LEAKS VOLUME – TIME SCALAR Expiratory
This is a volume-time waveform. Volume is delivered on the inspiratory phase of the graph and volume is returned during the expiratory phase. All the volume that is delivered is returned. This paitent has no leak. Time © MAQUET 34 MCV REVA 34

LEAKS As mentioned before, there are three graphs that will help detect leaks, all volume related. Look at the volume-time scalar. Volume is delivered but it is not fully returned. The expiratory curve should return to baseline. Look at the Volume-Pressure loop. The volume is on the y-axis. This loop should close as expiration ends. It doesn‘t in this loop. Look at the Flow-Volume loop. The volume is on the x-axis. The volume is delivered but not returned. Notice the VTi and VTe are off by about than 130ml. © MAQUET 35 MCV REVA 35

LEAKS This is the same main screen with the leak repaired.
The Volume –Time scalar‘s expiratory graph returns to base line. Both loops fully close as well. The delivered volume is returned. Notice the VTi and VTe are very close denoting all of the volume has returned. © MAQUET 36 MCV REVA 36

Waveforms should start at the baseline and end at the baseline.
LEAKS INSPIRATORY CYCLE OFF 2.5 seconds Waveforms should start at the baseline and end at the baseline. Let‘s talk about pressure support breaths. Volume support breaths cycle off the same way: flow-cycle. As mentioned before there is a pressure back up cycling criteria. There is also a time-cycle back up. If the flow does not decelerate to the ICO % and the patient does not pressure-cycle the breath off, the breath will cycle off after 2.5 seconds. (1.5 seconds in Infant catagory) A leak may cause a pressure support breath to time cycle because the ICO is not set high enough. © MAQUET 37 MCV REVA 37

MODES OF VENTILATION FLOW-CYCLING Peak Inspiratory Flow 50% 25% Flow
Pressure Support and Volume Support both cycle from inspiration to expiration the same way: flow-cycling. In flow-cycling, the inspiratory phase of the breath cycles off into expiration when the variable flow decelerates to a certain percentage of the peak flow of the breath. Older ventilators have a set percentage. The Servo I has a parameter called Insp Cycle Off. This is that percentage. If the ICO is set at 50% the breath will cycle off when the inspiratory flow declerates to 50% of the peak flow. If the ICO is changed to 25% and everything remains constant the breath will not cycle off until the peak flow decelerates to 25% of the peak flow. Flow 50% 25% Time © MAQUET 38 MCV REVA 38

LEAKS INSPIRATORY CYCLE OFF
The “igloo” or “fish mouth” on the Volume-Time curve is the classic picture of a leak! Use the ICO control to deal with leak situations by limiting the inspiratory time in support modes in the interest of patient comfort. Increasing the ICO will allow the clinician to stay in pressure support or volume support and help the patient exhale when they want to. © MAQUET 39 MCV REVA 39

AUTO-PEEP LOOK AT FLOW Flow - Time Scalar Flow - Volume Loop
Auto-PEEP can be easily detected on graphics by looking for FLOW. Of the three scalars and two loops that the Servo i displays, the following can be used to detect Auto-PEEP: FLOW-time scalar FLOW-volume loop © MAQUET 41 MCV REVA 41

AUTO-PEEP Look at the FLOW-time scalar‘s expiratory graph.
Flow should return to baseline. If it does not the patient is trapping air. Look at the FLOW-volume loop. The expiratory flow should return to zero on the y-axis. In this additional values page on the right, there is a value called Vee. Vee stands for end-expiratory flow. It should read zero. In this case the value is 20 lpm. © MAQUET 42 MCV REVA 42

Waveforms should start at the baseline and end at the baseline.
AUTO-PEEP Waveforms should start at the baseline and end at the baseline. 13 total pressure - 5 peep set = 8 auto peep If the expiratory flow curve does not return to baseline before the next inspiration starts, the patient is trapping gas. The Pressure-time scalar can be used in obtaining an auto-PEEP measurement. If the patient is not spontaeously breathing a measured Auto-PEEP can be obtained. On the third additional patient values screen, which is the mechanics page (all white), a total PEEP can be recorded. Press the Exp Hold hard key on the lower right section of the user interface, under the shield, until the message appears in the upper left of the main screen Exp. hold active. In this example the PEEPtot or total PEEP is 13cmH2O, the set PEEP is 5 cmH2O. The auto-PEEP for this patient is 8 cmH2O © MAQUET 43 MCV REVA 43

OPTIMIZING I-TIME Generally speaking, in decelerating flow modes, the Ti should be set to that the inspiratory flow just reaches the baseline before expiration starts. By doing so in the PC mode, tidal volume can be maximized for any given pressure level; By doing so in the PRVC mode, PIP can be minimized for any given tidal volume. Volume – Constant Flow Pattern Pressure –Decelerating Flow Pattern These are two example of machine breath types: volume on the left and pressure on the right. The volume breath uses a constant flow pattern and the pressure breath utilizes the decelerating flow pattern. When a patient is assisting in his breathing it is important to match the set I time to the patients neural I time. When the patient is receiving only controlled breaths and the patient is not assisting Notice it is very easy to detect a properly set I-time when using the decelerating flow pattern because the flow returns to baseline, where this is not visualized when using a constant flow. © MAQUET 46 MCV REVA 46

SHORT I-TIME Volume – Constant Flow Pattern
Pressure –Decelerating Flow Pattern Here we can see it is very easy to spot a short I-time on a decelerating flow pattern, but there is no real indicator that the I-time is to short when using the constant flow pattern. The flow on the decelerating flow has not returned to zero on the inspiratory phase. If the I time is extended to the point of zero inspiratory flow more volume can be delivered to the patient because flow over time = volume. © MAQUET 47 MCV REVA 47

LONG I-TIME Generally speaking, in decelerating flow modes, the Ti should be set to that the inspiratory flow just reaches the baseline before expiration starts. By doing so in the PC mode, tidal volume can be maximized for any given pressure level; By doing so in the PRVC mode, PIP can be minimized for any given tidal volume. Volume – Constant Flow Pattern Pressure –Decelerating Flow Pattern Again, with the decelerating flow pattern it is easy to spot a “zero flow state” which is a result setting the I-time too long. Moreover, the constant flow has no indicator the I-time may be too long. If there is any chance of a patient assisting the ventilator there should never be a zero flow state. The patient would instantly would become asynchronous. In patients with severe oxygenation issues some practitioners want to have an extended I time, which they believe may promote recruitment by increasing MAP. There are other ways of utilizing other modes to achieve the same MAP such as Bi-Vent. © MAQUET 48 MCV REVA 48

ASSESSING PLATEAU PRESSURE
To properly assess plateau pressure you must view the pressure-time scalar to ensure it is a true plateau. © MAQUET 49 MCV REVA 49

ASSESSING PLATEAU PRESSURE
To obtain a plateau pressure, press and hold the hard key Insp. Hold on the bottom right of the user interface. Hold it until a meassage appears in the upper left of the touch screen Insp. hold active. The plateau will appear in the patient values on the second page. © MAQUET 50 MCV REVA 50

TRIGGER AND CYCLE ASYNCHRONY
MONITORING EDI AND NAVA TRIGGER AND CYCLE ASYNCHRONY Mode: PRVC When an Edi (electical diaphramatic activity) is being monitored via an gastric tube with electrodes at the diaphramatic level (Edi catheter) asynchrony can be identified. In this example, the Edi waveform on the bottom in microvolts is transposed on the pressure-time scalar in the PRVC mode. There are two full machine breaths in this graph. The patient has asked for four in that same time frame as evidenced by the Edi waveform. © MAQUET 51 MCV REVA 51

PATIENT SWITCHED FROM MONITORING EDI TO NAVA
MONITORING EDI AND NAVA PATIENT SWITCHED FROM MONITORING EDI TO NAVA Mode: NAVA This same patient is now switched to the NAVA mode. Every neural effort is in synchrony with the ventilator delivery; timing, duration and degree of assist. © MAQUET 52 MCV REVA 52

EARLY SMALL AIRWAY COLLAPSE
Severe COPD patients with early small airway collapse can have graphics that look like this. Waves on the flow as well as pressure expiratory graphics. It may also be accompanied with trigger asynchrony. The ventilator must be responsive enough to see this graphically, such as the Servo I. Most of the time the waves on the pressure and flow will disapear with and increased PEEP setting. © MAQUET 53 MCV REVA 53

This is the same patient with an increased PEEP to 10 cmH2O. Notice how the sawtooth like waveform on exhalation deminished with the increased PEEP. The added PEEP may have improved the stability of the airways. This could be found in any mode. © MAQUET 55 MCV REVA 55

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