Phrenic nerve pacing, also known as diaphragmatic pacing, is a specialized medical treatment designed to assist individuals whose diaphragm muscles are unable to function effectively on their own. This therapy involves a surgically implanted device that helps regulate breathing by stimulating the phrenic nerves. The primary aim is to restore or improve a person’s ability to inhale, often reducing or eliminating the need for mechanical ventilation.
When Phrenic Nerve Pacing Is Used
Phrenic nerve pacing is considered for individuals with breathing difficulties due to impaired diaphragm function, provided their phrenic nerves remain intact and responsive. A common reason for this intervention is a high spinal cord injury, particularly those affecting the cervical spine at or above the C3 level. Such injuries can interrupt signals from the brain to the diaphragm, leading to complete or partial paralysis of the primary breathing muscle. In these cases, pacing can help restore respiratory function and improve overall lung health.
Another condition where phrenic nerve pacing may be utilized is central sleep apnea (CSA), a disorder characterized by pauses in breathing during sleep because the brain fails to send correct signals to the diaphragm. While less common than for spinal cord injuries, transvenous phrenic nerve stimulation has been approved for moderate to severe CSA in adults, offering an alternative to conventional positive airway pressure therapies. This can be helpful for patients with cardiovascular issues, as CSA is highly prevalent in those with heart disease.
Certain neurological diseases affecting the phrenic nerve or diaphragm, such as Amyotrophic Lateral Sclerosis (ALS), have also been explored for phrenic nerve pacing. However, pacing in ALS patients has been a subject of debate, with some research indicating that early intervention may not delay the need for non-invasive ventilation and could potentially shorten life expectancy. Despite this, some physicians still consider it in specific cases where diaphragm function can be stimulated.
The Pacing System and How It Works
A phrenic nerve pacing system consists of several components working together to facilitate breathing. These include an implantable pulse generator (IPG), electrodes (or leads) surgically placed near the phrenic nerves, and an external control unit. The IPG is often implanted under the skin in the abdomen or chest, while electrodes are attached to the phrenic nerves, which originate in the neck and extend down to the diaphragm.
The mechanism involves the external control unit sending radiofrequency energy to implanted receivers through antennae taped to the skin over the receivers. These receivers convert radio waves into electrical pulses. The electrical pulses are then delivered through the electrodes to the phrenic nerves, causing the diaphragm muscles to contract. This contraction pulls air into the lungs, initiating inhalation.
When electrical pulses stop, the diaphragm relaxes, allowing air to be exhaled. This cycle of stimulation and relaxation is repeated at a set respiratory rate, mimicking a natural breathing pattern. The surgical procedure for implantation often uses minimally invasive techniques, such as thoracoscopic surgery or laparoscopy. The procedure typically takes two to four hours, with patients discharged within one to two days. Medical professionals program and adjust the system to match individual breathing requirements, ensuring optimal performance.
Adjusting to Life with a Pacer
Following implantation of a phrenic nerve pacing system, there is an initial recovery period and rehabilitation phase. The pacer is not immediately activated; instead, a waiting period, typically six to eight weeks, allows incisions to heal and scar tissue to form around the electrodes, stabilizing them. During this time, patients may continue to rely on mechanical ventilation.
Once activated, transitioning from a ventilator to the pacer involves a conditioning and strengthening program for the diaphragm. Pacing sessions are gradually increased, starting with short durations, such as one to one and a half hours, to prevent diaphragm fatigue. Over several months, pacing duration is extended, with some individuals eventually achieving full-time independence from mechanical ventilation.
Living with a phrenic nerve pacer involves routine care and follow-up appointments to monitor system function and make necessary adjustments. The external control unit uses AA batteries, which need periodic replacement. The pacer can improve quality of life by enhancing independence, facilitating more natural breathing, and allowing for easier speech and smell. For many, it can reduce or eliminate the need for a tracheostomy (a surgical opening in the neck for ventilator connection), lowering the risk of infections like pneumonia. While the transition requires patience and consistent rehabilitation, benefits include increased mobility and a more integrated daily life.