The area of electrode placement is chosen based on location of larger contraction with strong preference for the posterior diaphragm to facilitate posterior lung lobe ventilation that will decrease atelectasis. Two electrodes are then implanted into the right and left diaphragm muscle. Placement of two electrodes in each diaphragm provides redundancy and synergy for maximal muscle recruitment. The electrodes are implanted using an implant instrument (Fig. 12.2 a, b). The electrode is threaded through the instrument to the tip of the needle. The needle at the end of the instrument is skived into the muscle, and the polypropylene barb on the end of the electrode releases upon withdrawal of the needle. The four electrodes and an anode are then tunneled subcutaneously to an appropriate exit site. A chest x-ray is taken at the end of the case to assess for the presence of a capnothorax that may result from carbon dioxide tracking from the abdominal cavity into the pleural space from the diaphragm. Small capnothoraxes resolve spontaneously where a larger one may need to be aspirated [5].

The implanted intramuscular electrodes are connected to a four-channel external pulse generator (EPG) (Fig. 12.3). This stimulator provides capacitively coupled charge-balanced biphasic stimulation to each subcutaneous electrode. The EPG is programmed with patient-specific parameters of pulse amplitude, pulse duration, inspiratory time, pulse rate, and respiratory rate by a clinician. DP users simply connect and turn the device on and/or off. The maximal settings for patient safety are 25 mA for amplitude, 200 for pulse width, and 20 for Hz. Patients should never exceed these parameters [5]. The goal for patient settings is to use the highest settings within the safety parameters that do not cause any patient discomfort.

Once implanted, the device can be utilized immediately to begin diaphragm conditioning. Each patient should have a customized conditioning program that entails initiation of DP use which gradually increases over time. Patients often begin with 30 min of DP use several times daily and increase usage every 3–5 days [3, 5]. DP conditioning will convert the atrophied muscle fibers from fast-fatigable type 2B muscle fibers to slow-twitch type 1.