(08-24-2013, 03:46 PM)Harryl Wrote: Timax. Currently set at 2
Ti min Currently set at 1
The current values you mention for these settings are middle-of-the-road typical values.
The TiMin and TiMax set the minimum and maximum time the machine will stay at the inhale pressure (IPAP) before dropping to the exhale pressure (EPAP). Your settings of 1 sec min and 2 sec max are typical for a person taking between 10 and 15 breaths per minute while asleep, which is very common. If a person has week inhale strength (because of disease or medication) a 1 second minimum will help ensure the machine will not "cycle" to the exhale phase too early, fooled by a tremulous on-again off-again weak inhalation. A 2-second maximum helps to ensure against so much time being spent in inhalation that little time is left for exhalation before the next breath needs to start. These parameters are less important when you are using a standard bi-level machine rather than an "ST" (Synchronous, Timed) bi-level machine. ST machines are used to treat central apneas. The Synchronous part means the machine will do its best to synchronize the pressure changes to your natural breathing rate (like most new machines these days, which have EPR or Flex or Pressure Support and all try to synchronize themselves to our natural breathing rate). The Timed part is for treating central apneas, when a bi-level ST machine will either continue changing between IPAP and EPAP pressures at your recent natural rate (even though you may no longer be making any effort to breath) or the machine may be set up to simply switch to a preset "backup" breathing rate, usually a number in the range of 10 to 12. The point is, if you have a bi-level ST machine, these parameters will be more important and may need fine tuning, based on your sleep data, which records statistics on the minimum and maximum ratios of the time spent in inhalation versus exhalation.
Trigger and Cycle refer to how sensitive the machine will be in Triggering the start of inhalation (a higher Trigger setting would be more sensitive and would cause the transition from exhale to inhale to occur easier/earlier/faster), and how sensitive the machine will be in Cycling from the inhale phase to the exhale phase (a higher setting for Cycle would be more sensitive, causing the inhale to terminate and cycle to exhale easier/earlier/faster). If it seemed to you that the machine was slow and lagging in changing between inhale and exhale, higher settings for Trigger and/or cycle may be more comfortable. On the other hand, if you see central apneas in your sleep data, lower settings for Trigger and/or cycle may reduce how many centrals you will have.
Max Ramp refers to the maximum amount of time the patient is allowed to select for Ramp.
Start EPAP is the low EPAP setting for use at the start of the Ramp period. Over the time period selected by the user, the EPAP pressure will gradually rise to the normal EPAP pressure (or will gradually rise to the Minimum EPAP pressure if the machine is an Auto bi-level machine which will automatically adjust itself between a minimum EPAP to some higher EPAP, as may be needed.
The Clinician Manual would have nice pictures of these things, and nice tables, to make everything more clear.