Atrotech Atrostim PNS Anwenderhandbuch Seite 54

Atrostim PNS
1 INTRODUCTION
In patients with sleep time central alveolar hypoventilation (CAH), i.e. with central
sleep apnea, the phrenic nerve stimulator Atrostim PNS may be used immediately
after the healing period of 10 to 14 days. In these cases the diaphragm muscle is
normal and thus conditioning is unnecessary (Glenn, Holcomb et al.1976).
In the typical case of respiratory muscle paralysis (RMP) and in cases with CAH
other than sleep apnea the muscle is hypotrophic. After disuse of several months,
several months may also be needed for conditioning of the muscle. Conditioning
should be planned in the same manner as training of sportsmen. Physical and
psychological problems may arise which need individual solutions.
Under natural conditions, tidal volume (TV) and respiratory rate (RR) are adjusted
almost breath by breath. The result is a certain minute volume, which meets the
metabolic needs of the patient. Increase of minute volume is achieved by increasing
TV and RR. TV is increased by increasing firing rate and recruitment of axons,
which results in more forceful contractions of a greater muscle mass during
inspiration.
For long-term PNS the current (I) is set to an amount (I
cause a TV which is "normal" for the individual patient. RR is set to a low value of
8-15 (for adults), 15-20 (pediatrics) breaths per minute. (Regard must be given to an
appropriate inspiration duration.) We suggest to accustom the patient to these
frequencies when still on a mechanical ventilator.
During the first trials of electroventilation, each of about 5 minutes duration, the
minute volume is looked for, which meets the patient's needs. To avoid discussions
about what a "normal" minute volume is, monitoring of p
The fatigue test can be performed once the minute volume parameters have been
established and after a sufficient resting period.
A special feature of Atrostim PNS is the inclusion of the sigh function. The
usefulness of the sigh function of mechanical ventilators to prevent malfunction of
the lungs is still questioned. In Atrostim PNS, the sigh function is intended to create
and keep available a reserve of conditioned muscle. When adjusting the current of
the sigh some overlap of stimulation compartments exists. It should be kept in mind
that the sigh function incorporated in Atrostim PNS is not intended to replace chest
physiotherapy. In clinical practice, the sigh has been set to about 30 - 50 % above the
effective stimulus current (i.e. I
If during the conditioning period TV is kept constant, TV can not be increased later
without a new conditioning period for the newly recruited motor units. For an acute
need, minute volume could be changed only by changing RR. This is because the
April 2002
Training procedure and follow-up
- I ).
TV TH
1
Training procedure and follow-up
) which is just sufficient to
TV
CO is recommended.
ET 2