19. Diaphragmatic/Phrenic Nerve Stimulation

Diaphragmatic/phrenic nerve stimulation is an alternate stand-in to mechanical ventilation for persons suffering from immedicable ventilatory insufficiency or failure. Suitable patients to receive benefit from this stimulation include those whose phrenic nerves and diaphragms are undamaged, and whose pulmonary function is satisfactory. The phrenic nerve begins from the cervical spine. It starts from the C3, C4 and C5 roots. It is the nerve that regulates and governs the movements of the diaphragm. The diaphragm is accountable for the volume of the air movement throughout natural breathing. The phrenic nerve stimulation device consists of an electrode surgically inserted and winding over the phrenic nerve. It is connected to a receiver operating at radio frequencies. This receiver is placed in the wall of the chest. Upon interception of radio-frequency signals from an external transmitter by an antenna that the patient wears over the receiver, regular electrical pulses are applied to the phrenic nerve. These pulses initiate contractions of the diaphragm, and the diaphragm contractions lead to the intake of air, similar to natural breathing. Hence, the implanted stimulator is called the breathing pacemaker. The respiratory rate is determined by the intensity, duration and rate of impulse. It is controlled by the external transmitter.