Atrotech Atrostim PNS Anwenderhandbuch Seite 8

Presurgical procedure
In most patients with central sleep apnea peripheral nerve and muscle
are normal. If the slightest doubt of malfunction appears, the
following tests should be performed also in patients with sleep apnea.
4. The conduction time of the peripheral phrenic nerve should be
measured, see section 3.
5. The function of the diaphragm muscle should be tested. At
supramaximal stimulation in the neck, the diaphragm should descend
at least 4 cm in adults. The test is performed using standard
conditions under fluoroscopy (Glenn 1985). The descent should be
recorded independently for both sides to provide normal values for
possible future trouble shooting. The test is most easily performed in
connection with the previous test (McLean & Mattioni 1981).
6. Ventilatory mechanics should be recorded. Most of the tests can be
performed as bed-side tests, at least in an ICU. They may be
repeated frequently without exposing the patient to the risks of
transfer to a laboratory and do not expose him to radiation.
Preferably they should be performed once during fluoroscopy. This is
because no normal values are available for patients with RMP, but
normal values have been established for the descent of the diaphragm
during fluoroscopy (Glenn 1985).
A good measure of diaphragm muscle function at supramaximal
stimulation would be the tidal volume achieved, the negative pressure
at airway occlusion, and the maximum inspiratory flow. The values
obtained in an individual patient could be used during the
conditioning period and later for follow-ups. Tests should be
performed unilaterally and bilaterally.
Normal values are also available for the trans-diaphragmatic pressure
(Roussos and Macklem 1977, Newsom-Davis 1979). However, this
test demands special equipment.
7. If necessary, muscle disease should be excluded by appropriate
enzyme tests and/or ENMG-studies.
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Atrostim PNS
April 2002