Download Central, mixed and obstructive sleep apnea patient

Central, mixed and obstructive
sleep apnea patient
Clinical scenario:
A 57-year-old male with a history of TMJ, bruxism and arthritis is not on any daily
medications but takes a daily multivitamin and Tylenol PM as needed.
In April, 2008, a sleep study was completed and the following information was provided
about the patient:
Sleep parameters
Diagnostic study
Sleep efficiency
84.9%
Apnea-hypopnea index (episodes/hr)
27.5
Central apnea index (episodes/hr)
5.6
Obstructive apnea index (episodes/hr)
1.1
Hypopnea index (episodes/hr)
18.4
Mixed apnea index (episodes/hr)
2.4
The above data indicated that the patient had mild-to-moderate sleep apnea with a mixture of both obstructive and
central events. He was sent home on a CPAP therapy of 9 cm H 2 0. The patient returned to the sleep center due to
increased complaints of Excess Daytime Sleepiness (EDS) and morning headaches. A repeat study was ordered and
the following information was found:
CPAP study
Clinical applications guide
33
Early in the night, during a CPAP titration, the patient was not on enough CPAP to eliminate obstructive hypopneas.
The obstructive nature of the hypopneas was suggested by snoring (see Micro channel) and the “peak-plateau”
inspiratory flow pattern (red arrow, and shown in detail in the next figure). Thoracic-abdominal paradox could also
be used to indicate obstruction, but the thoracic channel had cardioballistic and other artifacts that made it hard to
interpret.
A close up of the cardioballistic artifact is shown below on the THO channel.
An example of inspiratory flow limitation is indicated by the red arrow. Most of the breaths in this one-minute
tracing are flow limited. Flow-limited breaths have a “peak-plateau” or “scooped out” inspiratory flow pattern. In the
breath marked by the arrow, there is an initial peak in inspiratory flow, then a relative flattening, followed sometimes
by a secondary peak at the end of inspiration (zero flow is marked with the dashed line). This type of inspiratory flow
pattern is specific for upper airway obstruction.
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BiPAP autoSV Advanced—System One
Thoracic-abdominal paradox could also be used to indicate upper airway obstruction. However, cardioballistic
artifact in the thoracic belt made this difficult to identify in this patient. Note that each heart beat can be seen in the
thoracic (THO) channel.
Regardless, it is clear that PAP was not adequate and needs to be increased to treat the obstructive apneas
and hypopneas.
Clinical applications guide
35
Later in the night, CPAP at 8 cm H 2O appeared to eliminate upper airway obstruction. There was no snoring, flow
limitation, or thoracic-abdominal paradox (the cardioballistic artifact improved). Central apneas became apparent.
The patient had “CPAP-emergent central apneas” in which central apneas seemed to “emerge” from obstructive
hypopneas/apneas when CPAP was administered. The cause of these central apneas was not clear but may have
involved instability in the ventilatory control feedback loop or volume feedback from mechanoreceptors in the lung.
Upon completion of the CPAP study, the following was documented:
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Sleep parameters
Titration study
Sleep efficiency
88.7%
Apnea-hypopnea index (episodes/hr)
22.7
Central apnea index (episodes/hr)
10.6
Obstructive apnea index (episodes/hr)
0.4
Hypopnea index (episodes/hr)
11.7
Mixed apnea index (episodes/hr)
0
BiPAP autoSV Advanced—System One
BiPAP autoSV Advanced—System One titration
Since patient was previously on an auto CPAP device and having recurrent symptoms of a sleep disorder with an
elevated central apnea count, the physician tried the patient on a BiPAP autoSV Advanced—System One device.
Prior to the biocalibrations, the patient is drifting off to sleep and having sleep-onset central apneas. This is a
common occurrence as patients transition from awake drive-to-breathe to a chemical drive-to-breathe. BiPAP
autoSV Advanced—System One is detecting the central apneas and administering breaths. These ventilatortriggered breaths are recognized by the downward spike in the PatPress channel.
Clinical applications guide
37
This is a nice example of how the BiPAP autoSV Advanced—System One works. During the biocalibration
procedure, the patient was asked to hold his breath. After 4.5 seconds of apnea, the ventilator provided a ventilatortriggered breath. Note that there was no resulting inspiratory flow (downward arrow) because the glottis is closed.
Then the patient exhaled (upward arrow) and another ventilator-triggered breath was given. This time, the airway
was open and there was high flow. The next breath was patient-triggered and only received half the inspiratory
support as the previous breath.
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BiPAP autoSV Advanced—System One
Once the patient is asleep, BiPAP autoSV Advanced—System One helps to produce stable, regular breathing. Notice
the variation in inspiratory pressure (PatPress channel). The EPAP is 5 cm H 2O. The patient has a stable and regular
flow pattern (CFLOW) without central apneas. In this five-minute tracing, there are no ventilator-triggered breaths
however, there are many pressure support-triggered breaths supporting the patient while he sleeps.
Clinical applications guide
39
There are ventilator-triggered breaths in the first portion of this figure (indicated by downward spike in PatPress
channel). BiPAP autoSV Advanced—System One was preventing long expiratory pauses and central apneas. The
middle and last portions of the figure were patient-triggered breaths with progressively decreasing inspiratory
pressure; the patient is taking over more control of respiration. The flow rate is stable without pauses, apneas, or
variations.
Upon completion of the BiPAP autoSV Advanced—System One study, the following parameters were found:
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Sleep parameters
BiPAP autoSV study
Sleep efficiency
93.7%
Apnea-hypopnea index (episodes/hr)
6.4
Central apnea index (episodes/hr)
2
Obstructive apnea index (episodes/hr)
8
Hypopnea index (episodes/hr)
2.8
Mixed apnea index (episodes/hr)
0
BiPAP autoSV Advanced—System One