The portable phrenic nerve stimulator Atrostim PNS is a diaphragm pacing system for long-term artificial ventilation. Rhythmic contractions of the diaphragm are produced by delivering trains of current pulses to the phrenic nerves via multipolar electrodes attached on the nerves.
Atrostim PNS system consists of surgically implanted stimulators and electrodes, portable controller unit and transmitter coils that are attached on the skin over the stimulators for powering of the implants. The controller unit is operated with two rechargeable batteries, one battery in use and the other one fully charged in reserve.
Atrostim PNS utilizes Sequential Multipolar Stimulation. Features of Sequential Multipolar Stimulation – Four Active Nerve Contacts:
The phrenic nerve consists of smaller fibers or axons that innervate the different parts of the left or right diaphragm muscles (hemidiaphragms). The axons of the motor units arising from spinal C3 to C6 segments intermingle in the phrenic nerve before entering the muscle. One axon serves muscle fibers in about 70% of the diaphragm muscle by area. Therefore, when electrically stimulating one quarter of the nerve a contraction results in one quarter of the muscle’s fibers, but this quarter is almost evenly distributed over the whole muscle. Thus, a fused muscle contraction is achieved by stimulating the four nerve quadrants one by one and in sequence at a frequency which is on fourth of the frequency used in conventional monopolar electrode system.