The device provides electrical stimulation to the muscle and nerves that run through the diaphragm. When the muscle is stimulated, it contracts, causing a vacuum-like effect in the chest cavity that causes air to enter the lungs. When the contraction eases, the air is expelled passively. This process is repeated 10-14 times per minute. This is essentially the same process as normal breathing.

• Four Teflon embedded Electrodes: deliver a pulse directly to the phrenic nerve causing the diaphragm muscle to contract.
• The quadripolar system sequentially stimulates each of the four electrodes during a given breath, thereby decreasing the number of impulses delivered to a single quadrant of the phrenic nerve by 75% during inspiration. This quadripolar electrode system aims to eliminate the potential for diaphragm fatigue with prolonged pacing and allow for the situation-specific manipulation of pacer settings to meet the needs of an individual through stimulation setting changes by programming modules and the stimulus controller.
• Platinum/Stainless Steel Leads: connect the electrodes to the receiver and transmitter
• Radio receivers: translate the radio waves and stimulate the pulses.
• The radio receiver has a connector that is screwed into a titanium disc with an axial flange covered entirely by a woven double velour patch, which provides a barrier to infection.
• The electrode wires are crimped to the connector and embedded in silicone rubber.
• External transmitter/antenna assembly (portable control unit): receives its power from 9 volt batteries and sends energy and stimulus information to the patient.s receiver implant.

• Bilateral redundancy, including dual batteries - The bilaterally redundant design of the Mark IV provides greater safety than the S-232G transmitter.
• Amplitude range control - The Mark IV transmitter can provide greater resolution of stimulus amplitude by limiting the maximum output level.
• External breathing rate control - The Mark IV transmitter has the respiratory rate control (with a locking option) on the front panel. This is easier to operate than the S-232G transmitter, whose respiratory rate control was located in the battery compartment.
• Capability for a wider range of stimulus parameters - The Mark IV can be custom modified more easily than the S232G transmitter, should a patient require stimulus parameters that are different from the factory standard settings.
• Capability for asymmetrical parameters - Patients may require that parameters be set differently from one side of the body to the other. Such asymmetrical adjustment is not possible with an S-232G transmitter.
• Introduction of battery indicators - The Mark IV battery indicators use the latest advancements in light emitting diode (LED) technology to provide a simple, reliable method to verify adequate battery voltage and that the transmitter power circuitry is functioning.
• Introduction of antenna indicators - Like the battery indicators, the Mark IV antenna indicators provide a simple, reliable method to verify stimulus output and antenna integrity.
• Single circuit board design - The single printed circuit board design of the Mark IV is inherently more reliable then the dual circuit board design of the S-232G transmitter.
• Readily available electronic components - All electronic and mechanical components used in the Mark IV are in current production and readily available.