HSC Section 3 - Trauma, Critical Care and Sleep Medicine

ing toward the pleura. The lead is then anchored at two separate sites. The fixed anchor, which lies most proximal to the sensor, is addressed first. It is anchored to the fascia just outside the pocket, making sure to keep the ridges that run parallel to the anchor facing away from the chest wall. The second anchor is fixed, after a gentle loop is cre- ated, and should be positioned lateral and superior to the first. This site is then packed off with gauze soaked in a bacitracin-saline mixture. It is important not to use any sharp instruments to grasp the sense lead during the placement. Tunneling the Leads The leads for the sensor lead and stimulation lead are next tunneled with the provided disposable tunneling device. Some initial dissection with a Kelly clamp or the like is useful to shorten the distance that must be blindly tunneled. The sensor lead is tunneled first. This is done from the medial-superior aspect of the lateral chest wall incision and carried up to the inferior aspect of the anterior chest wall site. The stimulator lead is tunneled second. The device is bent to match the curve of the neck so that the lead will pass over the clavicle. Care must be taken to avoid the external jugular vein, having identified it beforehand where possible. The lead is brought out at the superior- medial aspect of the anterior chest wall site. The leads are then attached to the IPG in the prescribed manner. Device Interrogation/Verification The IPG is placed with manufacturer etching facing out and with leads attached, into the anterior chest wall pocket. It is interrogated first and then validated by test- ing the sensor waveform, and then by running stimulation

cuff over the nerve branches to be included. The lead is then passed under the digastric tendon in a gentle loop and anchored on its lateral aspect with two permanent sutures (Fig. 3). Bacitracin-infused saline should be irri- gated around and into the cuff to help evacuate any air retained in the cuff. This surgical site is then packed off with gauze soaked in a bacitracin-saline mixture. IPG Placement The IPG pocket is then fashioned. The pocket should be placed as medial as it is allowed from an aesthetics viewpoint. The anterior chest wall incision is made, and dissection is carried down to the fascia overlying the pec- toralis major muscle. Special care should be taken to avoid disrupting the fascia, as intact fascia will serve as the anchor for the IPG. A pocket is made in this location, approximately 5 3 6 cm in dimension, which will be suffi- cient to house the IPG. This pocket may be readily cre- ated with blunt dissection. It is also packed off with gauze soaked in a bacitracin-saline mixture. Placement of the Sensor Lead The incision for the sensor lead is made next and car- ried down through fat to the serratus anterior muscles. This is retracted superiorly, and the fifth and sixth ribs are identified. Blunt dissection is performed through the external intercostal muscle to identify the internal inter- costal muscle. A tunnel is made in between the external and internal intercostal muscles, approximately 6 cm in length (Fig. 4), taking care to avoid the neurovascular bundle on the inferior aspect of the rib. The sensor lead is then passed into this pocket. This should be facilitated by placement of a quarter-inch (0.6 cm) malleable retractor into the tunnel, with the lead being passed underneath it. Alternatively, it may be placed with a long clamp. It is crit- ical to make sure that the sensing portion of the lead is fac- Fig. 3. Placement of stimulation lead and cuff on the hypoglossal nerve (CN XII) from the surgeon’s intraoperative view with the head of the patient oriented to the left. The stimulation cuff distal end points anteriorly. After tunneling the lead underneath the digastric tendon, the stimulation cuff anchor is fixed on the digas- tric tendon, forming a loop to relieve strain on the stimulation cuff associated with neck motion.

Fig. 4. Placement of the sense lead in the intercostal muscles. The distal end of the sense lead is placed between internal and external intercostal muscles parallel to the adjacent ribs. The two anchors on the sense form a generous omega-shaped loop to relieve strain on the sensor lead.

Heiser et al.: Operative Techniques for UAS

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