Lowenstein PrismaLine optimization

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Oscar Optimisation for Lowenstein

Prisma Smart & Prisma 20A Devices

Lowenstein PrismaLine machines produce a lot of overlays and event flags. If left in default view, this excessive data will overwhelm your OSCAR display. It will make it impossible for forum members and medical professionals, to quickly understand how you are responding to your machine and its settings. Here are a few tips to help clean up that display and make the detailed data your machine is producing, a lot more meaningful.

If you are starting with a fresh Oscar install make sure to optimize first according to apneaboard recommendations here:

https://www.apneaboard.com/wiki/index.php?title=OSCAR_Chart_Organization

	Event Types Let's start by cleaning up the excessive event types. Goto the indicated drop-down at the bottom of the page and select only those event types circled near the top in red. These events are the main ones we are interested in.
	Flow Limitation Flag Color Flow limitation flags can be very visually distracting when there are a lot of them and they are colored black. Change from black to something much milder, like orange or dark yellow. Goto file > preferences > events tab. Double click on the color swatch for flow limitations. The color scheme seen in these examples was used to tone out some of the psychedelia. Any simplification of appearance can be an advantage when going over data with scowling industry professionals. Major event flags are colored mid to dark blue, RERA orange and flow limitations dark yellow.Under the waveforms tab, most waveforms have been set to grey and dark grey.
	Adjust y-axis scaling For a clean and consistent view of your breathing flow rates, right click the Y-Axis (left side) of the flow rate chart and set the Y-Axis to override. Set the axis to -120 min and 120 max. This will give a good all round view of nice regular breathing, along with clear indication of any 'arousal spikes'. While you are in the Flow Rate chart menu, remove all overlays. Finally, click & drag the bottom border of the Flow Rate graph and resize to your preference.

Advanced users may set Y-Axis over-ride on many of the other charts as well. This increases user friendliness and read-ability. Otherwise, outlier data can re-scale the chart, causing irregular display of the main data and confusing day to day comparisons. The increments of Y-Axis may also end up in strange divisions. On the included examples, most of the Y-Axis have been overridden to give a repeatable and consistent view of each metric. Y-axis overrides that increase usefulness are, leak rate 0-50 with dotted line at leak threshold and tidal volume 0-1000. Mask Pressure & Pressure can benefit from overide by setting to a tighter range around your own specific pressures. Try make all Y-Axis increments equal whole numbers. A dotted line at max mask pressure can be handy if using APAP.

Finally, but maybe most helpful for interpreting your data, is to create at least 2 profiles. The first one I call 'compact' and the other 'detailed'. In the compact profile, shrink the height of as many data rows as possible. Size the flowrate graph so the spike ups are not too prominent, but the biggest are still easily seen. This will give you a good general picture of a nights therapy. Most full charts pictured in this wiki are using this compact view.

However, this compact view will not be best for analyzing breath shapes and fine tuning therapy settings. This is especially true as soon as you start using bi-level or any variant of it, like softpap or epr etc. For this you will want a profile you can switch too quickly with a couple of critical changes to at least Flow Rate and Mask Pressure. In order to set these for best viewing, you should make sure the y-axis override is not too far off the actual flow rate and your pressure range. Make sure your oscar window is maximized or a least how you usually view it. Pick the best section of one of your best nights. Zoom in with left click until the flowrate duration is 1 minute. From here, drag the row height so that each inhalation is close to semi circle, without being too tall or too squat. Roughly match the mask pressure signal to the same height as each breath signal, so they are relative to each other.

Note: Consistent viewing will be dependent on your window size and flowrate duration being the same as they are when you set this.

Without a set baseline and zoom like this, you will not get as good a sense of each day compared to one another. Breaths can appear far taller or flatter, all dependent on these variables. If you are wanting to see subtle change in breath dynamics with a change in pressure support for eg. then this is very helpful.

Extra Settings for Prisma Bi-Level Devices

Apart from the above display settings, Lowenstein Bi-level devices can need some extra tweaking.

	Display Deep-Sleep In Bi-level modes deep-sleep is no longer displayed. This data is based off of the rRMVFluctuation signal. When this waveform drops to less than 1.50 it indicates a period of deep-sleep. So if you would still like to easily view your estimated deep-sleep, which is very useful for assessing therapy changes, then you can do this by overriding the autofit y-axis scaling to only show a max of 1.50 Any visible waveform sections will then denote deep sleep periods. Besure to uncheck DS(deepsleep) event type in the dropdown of your main display, if it is not displaying anymore.
	User Defined Flow Limitations Many Prisma therapy modes don't show flow limitations in Oscar. When this is the case (Resmed users included) you can utilize the custom event flagging in Oscar preferences. Setting the second user definable event to a percentage of 70% and length 7sec gives quite an accurate representation of these events.
	User Defined Flow Limitations 2 Rename the event to something like User Defined Flow Limitation and the flag to UDFL. Select its overview option if you would like to see flow limitation over time in the statistics overview screen. Finally, in your event types drop down, deselect the non working FL and select your new UDFL event. NOTE If the custom flags are not showing after restarting Oscar, you will have to use the 'rebuild cpap data' menu option.

PrismaLine CPAP & APAP modes

SoftPAP Compared to EPR

There is quite a difference in the so called "comfort" settings of the various CPAP & APAP machines. These comfort settings are in fact, limited versions of Bi-level or Tri-Level modes of therapy. These modes in a lot of instances, form the basis of the multi-Level therapy found on higher level machines which are normally used for more complicated ventilation needs.

Lowenstein SoftPap is here compared in application to the EPR of Resmed.

Algorithm differences

Below is Oscar's representation of the changing pressure whilst using Softpap2 at a CPAP pressure of 12cmH2o. This offers a pressure support of 3cmH2o. This is the maximum PS achievable with the Prisma Smart and delivers the same support as Resmeds EPR 3, although as you will see, the differing air delivery of the two devices affects how this pressure support affects breathing.

We can see clearly, the bi-level algorithm in use by Lowenstein. Notice that following the drop from IPAP to EPAP, the machine immediately begins to ramp back up to IPAP pressure. It meets closely with the beginning of inspiration. This is how Lowenstein achieves Apnea control at lower pressures. By returning to max pressure near the end of exhalation (when Apneas develop), the airway is fully supported.

In contrast, the Resmed example below shows the very different implementation of its Bi-Level mode. The lower EPAP pressure is maintained, it does not provide a movement toward IPAP pressure until the beginning of inspiration. Full IPAP is not reached until mid to late inspiration.

Often when pressure is insufficient, you can see in a Resmed trace, the second hump in the flow rate and/or the fuller second half of inspiration. The example above has pressure set to 6cmH2o and with EPR of 2 (a common minimum pressure new users are sent home with). You can see the obvious instability. This is why with a Resmed machine, the moment you switch on EPR, you must increase minimum pressure.

This same principle is not generally needed with Lowenstein. This is because of how each Bi-Level mode is implemented. You must use each tool by simply understanding how each works.

Response to Events

Another consideration when setting either SoftPap or EPR, is how each responds during an event. Resmed machines maintain EPAP pressure during events, whereas Lowenstein maintains IPAP or EEPAP pressure. EEPAP is your main set pressure without the 1cnH2o applied ontop during Tri-Level mode.

Resmed EPR3

Lowenstein SoftPap2

Flow Limitations

Lowenstein softPAP 1 & 2 algorithm favors Apnea control at lower pressures, but does come at a cost in some individuals. If you look closely at previous example, you can see the holding of steady pressure right through inspiration, can allow inspiratory instability in susceptible persons. UARS sufferers may experience persistent narrowing of the airway when this mode of therapy is applied.

This is where Softpap3 or Tri-level support comes in. This mode is introduced in the Prisma20a models and beyond. In this mode the machine addresses the problem of flow limitations by adding an extra level of inspiratory support. This mode applies an extra 1cmH2o to your set machine max pressure. This raises your IPAP by 1cmH2o and leverages the increasing pressure and flow to stabilize the airway. This mode has different trigger points for following your breathing pattern.

Normally, in regular Softpap and EPR, the ramp rate is constant. Here, you can see in the example below, that the ramp rate of Softpap3 or Tri-level mode, increases and decreases to stay in time with shorter and longer breaths. The maximum pressure support offered by Tri-Level mode is 4, but only @ 12cm H2o and beyond. Below is a period of flow limitation that softpap 3 is managing.

Unfortunately for Prisma Smart users, this mode of support is not available.

As you can see, each of these machines must be approached very differently in use. They are tools with various modes of operation, different strengths and weaknesses. Lower level machines are factory limited to reduce the amount of useful pressure support. These entry level machines are often only useful for rudimentary control of OSA. Many people who turn up seeking help actually just need these Bi-level or Tri-level modes properly applied. In quite a few instances, more levels of pressure support and trigger adjustments etc will be needed and so a step up in machine required. You would be advised to quickly figure out if your machine will do what it needs to. Stop torturing yourself if you need to move to a better machine.

SoftPap Application in Detail

SoftPap pressure support is variable as pressure goes up. This is best explained visually with another chart. Gotta love charts. Remember that PrismaSmart only has access to the first 2 levels of softpap. Prisma20a and above to level 3 softpap, which is really Lowenstein's Tri-level mode.

You can see that as cpap pressure is increased, the size of pressure support increases at set intervals. 8cmH2o and 12cmH2o are key pressures when this happens. You can have a situation where your IPAP is increased by double that of your EPAP. You can also maintain constant EPAP, whilst auto apap increases your IPAP pressure like this below. Where this could come into play is if you are sitting just beneath one of these pressures with your Apnea well controlled but can benefit from a bump in upper pressure limits during REM. If a user is shy of high pressure, or suffers aerophasia around one of these pressures, this smaller step in EPAP can help. You could, as above image shows, set APAP with a range of 11.5cm to 12cm & softPap 3. During REM or a positional change etc, the extra support kicks in on any flow limitations that develop with virtually no detectable EPAP increase. The Prisma20a can hold this extra pressure for just the right length of time during a rough patch, before letting you back down. This may only put you into aerophasia territory for a very limited time the whole night and minimizes disturbances from moving pressures. Also of note, is what happens at low pressures using SoftPap. On SoftPap 3 the first few pressures are identical. I wonder how many beginners and doctors think they are gradually increasing their pressure over a period, when they are actually not changing anything but a number on the LCD display.

PrismaLine Bi-Level Modes & Machines

In tuning Bi-levels machines in particular, awareness of ventilation principles, pressure targeted ventilation (PTV) and volume targeted ventilation (VTV) are very helpful. PTV is used in cpap machines like those used for sleep apnea therapy. VTV on the other hand, is generally used for intubated critical care patients.

Each mode has a differing way of calculating and delivering air. VTV aims to hit a settable volume target, where pressure remains variable. PTV aims to hit settable pressure targets like IPAP and EPAP, whilst leaving volumes variable.

The major factor affecting use of each mode, is the mask or tube seal. Volume targeted ventilation, needs a good seal to be effective, any leaks are counted towards volume delivered. Intubation ensures this seal. Pressure targeted ventilation, which commonly use an external mask, naturally accounts for any leaks by simply ensuring that the pressure target is reached at all times. This can be done up until the point where you hit the leak redline, limiting the machines ability to meet its pressure target. PTV is the mode we are largely dealing with here.

With pressure targeted ventilation, obviously the correct therapy pressures must be set, but this is only the first part of the puzzle. Volume, is an important variable we must control. This is determined by the interaction of complex machine settings, user physiology and pulmonary condition. The variability of this system necessitates careful assessment of each of these three areas, to allow making informed choices when trying to achieve ventilation synchrony. This is a concept whereby machine and user are in time and satisfying the respiratory need, without fighting each other. This can cause arousal and very poor sleep quality, despite possibly having great apnea and hypopnea control.

Due to the increasing complexity of Bi-level support, and the miriad of adjustments offered by Lowenstein, a number of predetermined settings called "scopes" are provided in each bi-level mode. These presets are designed and tested to be used as a starting point for differing pulmonary conditions and co-comorbidities.

These scopes are:

• OVERLAP which is designed for users with obstructive sleep apnea and mild to medium COPD.
• HYPOV which is designed for users with nocturnal hypoventilation.
• OSAS which is designed for users with severe obstructive sleep apnea and a high pressure requirement.

We are going to try explore the various settings available within these "scopes", for essentially creation of your own personalized "scope". Your custom scopes can be saved and recalled from within the PrismaTS software and uploaded to a device via LAN or SD card. Of course manual adjustment of each individual setting is always possible via the machine panel.

The Settings

One of the first settings to grasp on Lowenstein Bi-level machines, is BisoftPAP. This alters pressure settings and shapes the air delivery algorithm dramatically. It is adjustable in every mode except for T. The four settings are BiSoft0 (Off), BiSoft1, BiSoft2 and TRILevel

BiSoft modes apply a gradual ramp upto a pressure level known as EEPAP (end expiratory positive airway pressure). This end of expiration pressure is applied at the most critical time for airway collapse and provides important airway stenting, in preparation for inspiration. It can limit central apnea, round out exhalation and permit generally lower pressures. In using Tri-level, Lowenstein recommends setup in a Bi-Level stage first, then apply Tri-Level option to use their predetermined comfort 'pressure reduction'. Lowenstein recommend return to Bi-level for further adjustment.This is due to the machine adding and subtracting pressure from IPAP and EPAP with an unseen algorithm at certain pressures, which can confuse settings.*Each of the Bi-soft levels divide pressure and increased flow between exhalation and inspiration phases. This can be leveraged to target the weakness or instability in your breath shapes.

Study of your flow rate graph in conjunction with mask pressure will be invaluable in fine tuning therapy settings.

BiSoft0 (Off) is useful for late collapse of inspiration. This mode will delay the arrival of maximum pressure support and help fill out the second half of the inhalation.

BiSoft1 & BiSoft2 can begin deliver some extra support to late exhalation, but is most useful for directing a large amount of pressure support at early to mid inspiration when it is lacking.

TRILevel can be used to apply the greatest amount of pressure during end of expiration. This is ideal for those with collapsing exhalation and instability during time at zero and into early inspiration.

Ramp Pressure rise time can be set to three levels and affects the duration of the inspiration ramp. This will move the centre point of max ipap pressure to the beginning, middle or end, of your inspiration period. Use to round out your breath shapes promoting comfort and stability.

Ramp 1 sets max ipap pressure to arrive early, filling out the first half of inspiration and gives the longest duration at peak pressure

Ramp 2 sets max ipap pressure to arrive somewhere in the middle of a breath and moderate duration at at peak pressure

Ramp 3 sets max ipap pressure to arrive later in the breath and the least length of time at peak pressure

Further adjustments to the flow shape can be made.

| Trigger An inspiratory trigger sensitivity is settable in 3 stages or can be left on Auto for the machine to determine. This determines how far into a spontaneous breath the machine will wait to trigger further support.

Ti/Tset The relative inspiration duration can be set between 25% - 67%. This controls the threshold of peak flow for cycling to expiration.

Nearly all of these settings can be affected by one another and also the size of the minimum and maximum pressures set. If you keep your volume goal in mind and utilize breath shapes displayed by Oscar, you can learn quickly what tool or combination of tools you need to use.

Anticyclic Servoventilation

The PrismaCR models of Lowensteins PrismaLine range offer an ASV mode for treatment of central and mixed apnea.

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