Minimally Invasive Repair of Pectus Excavatum (MIRPE)
The pectus bar is selected and prepared as previously described (see Preprocedural Planning).
Placement of incisions and creation of skin tunnel
A transverse 2-cm skin incision is made on each side of the chest in the midaxillary line at the level of the skin marks in line with the deepest point of the depression of the sternum.
A skin tunnel is raised anteriorly from both incisions to the top of the pectus ridge at the previously selected intercostal space; the skin pocket is extended posteriorly to allow the distal end of the pectus bar to hug the chest wall posterior to the midaxillary line.
Insertion of thoracoscope
A 5-mm thoracoscope is inserted at this point. The authors recommend placement of a 5-mm blunt trocar one or two intercostal spaces below the space chosen for the pectus bar on the patient's right side. A 30° 5-mm thoracoscope provides excellent visualization of the pleural cavity, lung, and mediastinal structures. If necessary, the scope can be used bilaterally. Insufflating the pleural cavity with carbon dioxide is rarely necessary; in most cases, controlled ventilation by the anesthesiologist with small tidal volumes results in limited lung expansion and good thoracoscopic visualization of vital structures.
Insertion of pectus introducer
The skin incisions are elevated with a thin but deep retractor, and the intercostal space previously marked is identified. An S-shaped device known as the pectus introducer is inserted through the appropriate right intercostal space at the top of the pectus ridge (usually at the level of the midclavicular line), in line with the point that corresponds to the deepest depression of the sternum (previously marked).
The introducer is slowly advanced across the anterior mediastinal space immediately under the sternum with careful videoscopic guidance. It is important always to direct the point of the instrument anteriorly (away from the heart) and to maintain contact with the sternum so as to avoid injury to mediastinal structures.
The sternum is forcefully lifted as the instrument is passed to the contralateral side. Thoracoscopic visualization and monitoring for cardiac ectopy are important to ensure that the instrument is not near the heart or pericardial sac.
Once the instrument is passed behind the sternum, the tip is pushed through the intercostal space at the top of the pectus ridge on the left side (also previously marked) and brought out through the left skin incision (see the image below). Thoracoscopy on the left side is not usually necessary unless the position of the instrument in the left chest is uncertain.
Nuss procedure. Minimally invasive technique for correction of pectus excavatum (3) with thoracoscopy (1). Note long clamp passed from one side to other (2) to grab umbilical tape (4), which serves to guide passage of pectus bar behind sternum.
A technical note is that the pectus introducer comes in two sizes: short, for younger patients aged 4-12 years who have a small chest; and long, for older and larger patients aged 13-20 years.
Placement of pectus bar
With the introducer, a strand of umbilical or tracheostomy cloth tape is pulled through the tunnel; the tape functions as a guide for placement of the pectus bar. The curved pectus bar is attached to the tape and then advanced under thoracoscopic guidance and by using traction on the tape.
The bar is inserted with the convexity facing posteriorly so that the bar is between the sternum and the mediastinum (see the image below).
Nuss procedure. Pectus bar after being passed behind sternum (5), under thoracoscopic visualization (1), and before being turned over. Note that concavity of bar is facing up.
With the help of a pectus bar rotational instrument (also known as a "bar flipper"), the bar is turned over so that the concave part faces posteriorly (to the mediastinum) and the convex part faces anteriorly (against the sternum). The ends of the bars are placed in the subcutaneous tissue, anterior to the muscle fascia (not under it and not within the muscle tissue). Again, the bar must hug the chest so that the ends do not protrude under the skin pocket (see the image below). The "flipping maneuver" is also performed under careful thoracoscopic visualization.
Nuss procedure. Pectus bar passed behind sternum before and after being turned over. Inset shows proper technique for fixation of pectus bar against lateral chest wall musculature.
If, after the bar is flipped, the correction of the pectus excavatum is not ideal (ie, either undercorrected or overcorrected), the bar is flipped back, pulled back out, and bent again to fit the patient's chest so as to achieve the best possible correction of the deformity. If pressure has caused the bar to straighten, it is turned over, and the curvature is increased as appropriate by using small handheld benders.
This can be repeated as many times as necessary. Typically, only one bar is necessary to correct the deformity, but, occasionally, a second bar may be required. The second bar can be placed above or below the first one. The image below is a representation of the thoracoscopic images of the bar placement across the anterior mediastinal space (anterior to the heart).
Nuss procedure. Thoracoscopic images at time of minimally invasive repair. (A) Pectus bar passer behind sternum and next to mediastinum and pericardial sac. (B) Umbilical tape being passed across anterior mediastinal space. (C) Bar being passed across anterior mediastinal space (anterior to heart). (D) Pectus bar flipped and resting under sternum. (E) Third point of fixation of pectus bar.
Stabilization and securing of pectus bar
Once the bar is in place, determining its stability is imperative. The results of this determination dictate the need for placement of a stabilizer bar. The stabilizer serves to limit rotation of the pectus bar and is sutured around the bar and to the muscle only after being properly fitted.
Teenagers usually require one stabilizer bar that can be placed on either side of the pectus bar. We prefer to place one stabilizer on the right side of the chest. If the bar does not feel stable, a second stabilizer on the left side can be placed. The stabilizers are secured to the pectus bar with #1 stainless steel wire sutures.
With the bar properly placed and stabilized, figure-eight sutures are placed to secure the bar and stabilizer to the lateral chest wall musculature. Nonabsorbable (polypropylene) 0 sutures are placed on the right side, and absorbable (polyglactin or polydioxanone) sutures are placed on the opposite side. This prevents the need for reopening both incisions at the time of bar removal.
Additionally, a third point-of-fixation suture can be placed on the anterior chest to the side of the sternum, around one rib and around the pectus bar, in order to provide another point of fixation for the bar and thereby minimize the chance of bar displacement (see the image below).
Nuss procedure. Position of pectus bar in relation to ribs and sternum, as well as location of third point of fixation.
Once the bar is in stable position, the lateral incisions are closed in layers with absorbable sutures. The skin should be closed with 5-0 poliglecaprone sutures and covered with Steri-Strips. Simple waterproof adhesive bandages are used as dressings.
End of anesthesia and completion of procedure
Before the chest wall incisions are closed, the anesthesiologist should place the patient in the Trendelenburg position, and large tidal volumes should be used in combination with positive end-expiratory pressure (PEEP) so that any residual pneumothorax is eliminated. A small temporary red-rubber tube placed through the trocar site can be used to evacuate any residual intrapleural air. The tube should be connected to suction or placed under water seal in order to allow elimination of most of the air inside the pleural cavity.
Postoperative Care
A postoperative chest tube is rarely needed. The anesthesia team must allow the patient to wake up with minimal cough and movement in order to prevent the risk of early bar displacement. Chest radiography is performed after surgery to confirm good lung expansion and to reveal the final positioning of the bar. The image below shows the placement of two pectus bars in a 17-year-old male with Marfan syndrome and severe pectus excavatum.
Nuss procedure. Chest radiograph of 17-year old male with Marfan syndrome and severe pectus excavatum, in whom it was necessary to place two pectus bars.
Medications and therapies typically depend on the patient's response to pain and usually include an epidural catheter, intravenous (IV) narcotics for breakthrough pain, patient-controlled analgesia (PCA; possibly augmented by ultrasound-guided bilateral intercostal nerve blocks [51] ), and selective use of nonsteroidal anti-inflammatory drugs (NSAIDs). [52] Continuation of morphine analgesia after postoperative day 1 may give rise to an increased incidence of urinary retention and nausea and vomiting. [53] Intercostal nerve cryoablation (INC) has been described as an alternative to thoracic epidural analgesia for pain after the Nuss procedure. [54]
Patient mobilization is permitted on postoperative day 1 or 2 by flexing the bed at the hip level and keeping the back straight. The patient is instructed to avoid trunk rotation or to sit in bed with the thoracic spine flexed. The epidural catheter is generally removed on postoperative day 3, and the patient should be fully ambulatory after that point.
After postoperative day 3, the patient is required to ambulate with the assistance of physical and occupational therapy. From postoperative day 4 or 5 onward, the patient is instructed in performing limited exercises at home to facilitate recovery. Ambulation is strongly encouraged from that point. The patient is discharged home once pain is adequately controlled with oral medications. The average length of stay is 4-7 days. Good posture with a straight back is very important, even after discharge.
In a study by Yu et al, application of an enhanced recovery after surgery (ERAS) protocol to the Nuss procedure shortened postoperative drainage time and postoperative hospitalization. [55] In another study, by Wharton et al, implementation of an ERAS for the Nuss procedure yielded significant reductions in length of stay, early pain scores, and urinary catheter usage, without increasing postoperative emergency department visits and hospital readmissions. [56]
Pectus Bar Removal
The bar generally remains implanted for 3 years; removal is done as an outpatient procedure with the patient under anesthesia. Nuss bar removal has detectable but small effects on diaphragmatic ribcage motion; these effects are unlikely to be of clinical significance. [57] No change in exercise capacity should be expected.
For the bar removal procedure, reopening the right side of the chest using the same surgical scar is usually necessary. This is the side that should have the stabilizer. Once the bar, stabilizer, and sutures are freed from the surrounding tissues, the pectus bar can be pulled out of the chest (see the image below). The bar is pulled out by using an instrument equivalent to a bone hook, in such a way that steady traction is applied and the bar is removed with its curvature brought almost under the operating room table. No need for repeat thoracoscopy exists.
Generally, complications after bar removal appear to be infrequent and relatively minor. [58] Surgical bleeding is the main complication of concern after removal of the pectus bar. [59]
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Typical appearance of (A) teenaged boy with severe pectus excavatum and (B) young girl with pectus deformity.
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Nuss procedure. Appearance of chest before (above) and after (below) Nuss operation for pectus excavatum. Image illustrates cosmetic advantage of minimally invasive approach.
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Noncontrast chest CT scan of patient with pectus excavatum. Chest Haller index is ratio of lateral (transverse) diameter of chest wall to anteroposterior diameter at point of maximal depression of sternum.
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Young infant with pectus excavatum.
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Nuss procedure. Range of pectus bar sizes available (7-17 in.).
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Nuss procedure. Technique for bending pectus bar on back table.
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Nuss procedure. Minimally invasive technique for correction of pectus excavatum (3) with thoracoscopy (1). Note long clamp passed from one side to other (2) to grab umbilical tape (4), which serves to guide passage of pectus bar behind sternum.
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Nuss procedure. Pectus bar after being passed behind sternum (5), under thoracoscopic visualization (1), and before being turned over. Note that concavity of bar is facing up.
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Nuss procedure. Pectus bar passed behind sternum before and after being turned over. Inset shows proper technique for fixation of pectus bar against lateral chest wall musculature.
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Nuss procedure. Thoracoscopic images at time of minimally invasive repair. (A) Pectus bar passer behind sternum and next to mediastinum and pericardial sac. (B) Umbilical tape being passed across anterior mediastinal space. (C) Bar being passed across anterior mediastinal space (anterior to heart). (D) Pectus bar flipped and resting under sternum. (E) Third point of fixation of pectus bar.
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Nuss procedure. Position of pectus bar in relation to ribs and sternum, as well as location of third point of fixation.
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Nuss procedure. Chest radiograph of 17-year old male with Marfan syndrome and severe pectus excavatum, in whom it was necessary to place two pectus bars.
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Patient with pouter pigeon breast. Note protrusion of manubriosternal junction and adjacent costal cartilages with S-shaped appearance of sternum.
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Nuss procedure. Pectus bar being pulled out of chest with bone hook instrument.
