Nuss Procedure for Pectus Excavatum

Pectus excavatum, also known as sunken or funnel chest, is a congenital chest-wall malformation in which several ribs and the sternum grow abnormally, producing a concave or caved-in appearance of the anterior chest wall and sternum. (See the image below.)

Pectus excavatum occurs in an estimated one in 300-500 births, with a 3:1 male predominance. The condition is typically noticed at birth, and more than two thirds of cases are diagnosed within the first year of life. Worsening of the chest’s appearance and the onset of symptoms are usually reported during rapid bone growth seen in puberty and early teenage years.[1] Many patients are not brought to the attention of a pediatric surgeon until the patient and the family have noticed such changes. Despite the lack of an identifiable genetic marker, the familial occurrence of pectus deformity is reported in 35% of cases.[2]

This topic focuses on the operative technique known as minimally invasive repair of pectus excavatum (MIRPE). It was originally described by Donald Nuss and thus is also known as the Nuss technique or pectus bar procedure. Nuss performed the first minimally invasive operation for the correction of pectus excavatum in the 1980s, but it was not until 1997 that this innovative technique was introduced to the American Pediatric Surgical Association and subsequently published in the Journal of Pediatric Surgery.[3]

Because of the early excellent results of the Nuss procedure and because of its less radical nature (as compared with the open Ravitch technique),[4, 5, 6, 7] the popularity of this operation has grown dramatically.[8]  (See the image below.)

Pectus excavatum patients are considered candidates for corrective surgery on the basis of the following criteria:

• Severity of the deformity (as determined by measurement of the chest Haller index)
• Resulting functional impairment
• Psychosocial impact of the deformity on the patient

The chest Haller index is a measurement taken from a noncontrast computed tomography (CT) scan of the chest in which a ratio is obtained between the lateral and the anterior-posterior diameter of the chest wall at the point of maximal depression of the sternum (see the image below). A normal chest index is around 2.5. Patients with an index greater than 3.2 have a fairly pronounced and severe pectus excavatum and will typically benefit from operative correction.[9] Even if asymptomatic, those patients usually benefit from the corrective surgery.

Of note, obtaining a chest Haller index in a young patient (see the image below) with pectus excavatum is not necessary. The Haller index should be obtained before corrective surgery (within months and not years) so that it can provide information helpful to the surgeon in planning the operative correction of the pectus.[10, 11]

Symptomatic patients with pectus excavatum typically experience occasional episodes of chest pain, shortness of breath with exertion, and decreased exercise tolerance. Such patients usually have abnormal pulmonary function test results, and echocardiography may demonstrate mitral and tricuspid valve regurgitation. Mitral valve prolapse is also commonly seen on the echocardiogram.[12, 13]

Many patients with mild-to-moderate pectus excavatum do not report any significant shortness of breath. Upon further questioning, however, one may find that the children are unable to keep up with their peers during play and physical activity.[14] They children usually report getting tired more easily.

Another common observation in children with pectus excavatum is that they are very shy and reserved about their physical appearance. Frequently, as summer comes around, they are unwilling to take their shirt off for sports, swimming, or around other children. The psychosocial stress caused by the abnormal chest can be quite severe and can result in a major adjustment disorder, depression, and even suicide ideation later in life.[15, 16]

The most common goal in operative repair of pectus excavatum is to correct the chest deformity. As noted above, this is particularly important with teenagers, in whom the abnormal appearance of the chest can result in significant problems related to body image and self-esteem. Thus, the desire to improve the appearance of the chest is considered an appropriate medical indication for surgery.[17]

The current recommendations support the use of MIRPE in patients aged 5-20 years. The ideal age for undergoing this operation has been established at 8-12 years because in this age range, the chest wall is still very malleable, stabilization of the bar is easily achieved, thoracic epidural can be safely placed, and the child is mature enough to understand the operation and postoperative instructions, particularly incentive spirometry, which is essential for minimizing pulmonary problems after surgery.[18]

Of note, operative correction of pectus excavatum should not be viewed as an operation limited exclusively to pediatric patients. Indeed, the open technique has been used in adult patients with excellent results. Although experience with MIRPE in adult patients has not been as extensive,[19]  there is evidence to suggest that similar principles apply to adult patients and that operative correction using MIRPE can be achieved in this population.[20, 21]

Limiting factors for MIRPE in adults include a larger chest wall and poor malleability of the ribs, cartilage, and sternum. A surgeon experienced in the field of chest-wall malformations must carefully evaluate adult patients to determine which operation would best correct the anatomic deformity.[22]

Moreover, adult patients with pectus excavatum who undergo open heart surgery have significant displacement and rotation of the heart to the left chest. This can make the operative approach to the heart at the time of open heart surgery very challenging. With this in mind, elective repair of the pectus deformity prior to open heart surgery may be indicated in selected adult cases.

In a retrospective multicenter study of 20 adult patients with recurrent pectus excavatum, Kocher et al found MIRPE to be safe and effective for repairing the recurrences after a failed Ravitch procedure.[23] The results were good to excellent in the majority of adults, and there were no major complications or further recurrences. Another study found that a modified MIRPE could be successfully used in most adults to revise a failed prior Nuss procedure.[24]

Patients with other associated complex congenital anomalies, neurodevelopmental delay, congenital heart disease with primary cardiac dysfunction, and chronic immunosuppression are not considered good candidates for corrective surgery for pectus excavatum. A comprehensive preoperative evaluation, including cardiology consultation and echocardiography, must be completed in order to determine the patient’s level of risk.

Best practices

Not all patients with pectus excavatum are considered candidates for corrective surgery. The decision to undergo surgery is based on clinical symptoms and the severity of the deformity. The surgeon, patient, and immediate family must reach a consensus as to the benefits of operative repair for the child with pectus excavatum. The morbidity and mortality of the surgical intervention must be taken into consideration.

Procedural planning

Patients must be selected carefully for the procedure. Preoperative assessment may include pulmonary function testing (PFT) and noncontrast CT of the chest. CT allows determination of the preoperative Haller index (as previously described). Patients with a Haller index higher than 3.2 are considered candidates for MIRPE. PFT typically demonstrates mild changes in pulmonary volumes (restrictive pattern).[25] Echocardiography is performed selectively in patients with clinical evidence of Marfan syndrome or with any cardiac symptoms or murmurs.

Complication prevention

Appropriate patient selection and careful attention to operative and technical details minimize the risk of complications.[26] Moreover, recognizing that the ideal age for operative repair is between 8 and 12 years of age is important.[27] Prepubertal patients have a more flexible rib cage, which facilitates reconstruction and remodeling of the ribs and sternum. Younger patients typically experience less postoperative pain and discomfort than teenagers and young adults do.[18]

Several studies have been published that evaluate the short and long-term outcomes after MIRPE. Overall patient and family satisfaction has been considered very good, with excellent and good results reported in more than 90% of cases.[28, 29, 26]

In 2000, a multi-institutional study that reviewed 251 MIRPE cases demonstrated a significant complication rate (overall incidence of complications was almost 20%).[26] The most common complication necessitating reoperation was displacement of the retrosternal stainless steel support bar (reported to occur in 9.5% of all patients). Such displacement can include a 90° rotation, a 180° rotation, or a lateral migration. Teenaged patients are at higher risk for complications, particularly pectus bar displacement, probably because of the increased pressure on the bar generated by a larger chest and a more rigid chest cage.

The rate of complications was found to be relatively high when many different surgeons performed the operation.[28, 26] This probably reflects the learning curve associated with the introduction of MIRPE. Since the first such procedure was performed, the bar has been modified several times; current bars are strong enough to withstand the pressure of even the most severe deformity.

Factors contributing to the suboptimal results reported include the softness of the bars initially used, the premature removal of the bar, and the failure to stabilize the bar adequately.[30] Experience has shown that stabilization of the bar is absolutely essential for success and that the use of a lateral stabilizing bar and the third point of fixation (when appropriate) can minimize the occurrence of bar displacement.[31]

The spectrum of adverse outcomes is variable, and most complications are considered rare and unusual.[28, 26, 32, 33, 34, 27] The following is a list of reported complications after MIRPE (and their estimated incidence):

• Pectus bar displacement ^[35] requiring reoperation (2.5%)
• Pneumothorax necessitating chest tube (3%)
• Overcorrection (3%)
• Epidural catheter complications (4%)
• Bar allergy (1-2%)
• Wound infection (1%)
• Pleural effusion (1%)
• Thoracic outlet syndrome (< 0.5%)
• Pericarditis (< 0.5%)
• Cardiac injury (< 0.5%)
• Sternal erosion (< 0.5%)
• Death (< 0.2%)

With respect to cardiopulmonary outcomes after MIRPE, one study demonstrated that objective measures of forced expiratory volume in 1 second (FEV1), total lung capacity, diffusing lung capacity, and respiratory quotient all showed significant improvement (after bar removal) in comparison with preoperative values, whereas normalized values of cardiac index at rest did not.[25]

It should be noted that this improvement in cardiopulmonary function is not necessarily seen during the time that the support bar is still in place. For that reason, functional outcomes should not be evaluated until the patient has completed treatment with bar removal. Of note, the dreaded complication of chest-wall constriction after Ravitch repair of pectus excavatum has not been reported with the Nuss procedure.

Attempts have been made to determine which technique (ie, MIRPE or open surgery) provides the better outcome in patients with pectus excavatum.[36]  Although many surgeons with expertise in the management of children with chest-wall deformities have shown some bias toward the use of the Nuss technique, this bias is not strongly supported by prospective randomized published data.

A systematic review by Johnson et al compared outcome measures for Nuss and Ravitch procedures (as well as other, less common approaches) in both pediatric and adult patients.[37] The results indicated slightly better outcomes with the Nuss procedure than with any other approach in children; in adults, the results did not lead to a preference for the Nuss procedure over the Ravitch procedure or vice versa, though both were preferred over the less common approaches.

Since the introduction of thoracoscopy and lateral stabilizers, as well as the third point of fixation technique, bar displacement has become quite unlikely, with an estimated incidence of less than 2.5%.[18]

A significant advantage of MIRPE over the open surgical procedure is that the dreaded complication of "thoracic constriction" (Jeune syndrome) does not seem to occur with MIRPE.[38]  Chest-wall constriction has been described in a few patients following extensive open pectus excavatum operations. Apparently, the bone-growth center can be affected, which results in restriction of chest-wall growth with marked limitation of ventilatory function. Such patients are very symptomatic and cannot compete in running games. The forced vital capacity (FVC) and FEV1 are typically decreased by more than 50% of predicted reference range levels.

With MIRPE, because no resection or incision is made on ribs or cartilages, such a complication does not appear to be a problem.[8]  Once the cartilage and bony structures are remodeled, normal or improved pulmonary function is established and the flexibility and malleability of the chest remains unaffected.

Critics of MIRPE claim that it is too invasive, poses substantial risks, and is not pain-free. Proponents argue that MIRPE, compared with open surgery (modified Ravitch operation), eliminates the need for an anterior chest-wall incision with creation of pectoralis muscle flaps, resection of several ribs and cartilages, and sternal osteotomies. MIRPE allows a much shorter operating time, causes minimal blood loss, and results in minimal surgical chest-wall scarring. Moreover, the stability and strength of the chest wall are not compromised, as is sometimes the case with open repair.

Data published in 2011 by the multicenter study group evaluating the pulmonary functional outcome of pediatric patients with pectus excavatum treated with MIRPE clearly demonstrated that the increasing severity of pectus excavatum is associated with reduced pulmonary function and that the Nuss operation can effectively reverse that process.[39]

Final data analysis generated by the multicenter study and published in 2013 clearly demonstrated that there is significant improvement in lung function at rest and in VO2 max and O2 pulse oximetry after surgical correction of pectus excavatum with a Haller index greater than 3.2. The study concluded that operative correction significantly reduces the Haller index and markedly improves the shape of the entire chest and cardiopulmonary function.[40]

The Nuss procedure has been associated with a greater degree of postoperative pain than the Ravitch procedure. However, a meta-analysis of 19 studies (N = 1731) found that the postoperative length of stay was similar for the two procedures and that the Nuss procedure (n = 989) was associated with shorter operating times and less blood loss than the Ravitch procedure (n = 742).[41]

Toci et al assessed outcomes in 290 adults undergoing Ravitch (n = 53) or Nuss procedures (n = 237) for pectus excavatum to determine whether postoperative complications and recurrence differed significantly between primary and redo operations.[42]  There were no significant differences in postoperative complications or recurrence rates between Nuss and Ravitch repairs overall, between redo Nuss repairs (n = 53) and Ravitch repairs (n = 26), between primary and redo Nuss repairs, or between primary and redo Ravitch repairs; however, there were significant differences between all Nuss and all Ravitch repairs with respect to age, length of stay, follow-up, bars inserted, and estimated blood loss.

It is important to note that there is a risk of significant complications with both the open and the minimally invasive approach to repair of pectus excavatum. A 2018 study reported the types of life-threatening complications related to minimally invasive repair.[43] As expected, the overall incidence of such complications was quite low (< 0.1%) and was not dissimilar to that associated with the open repair. Surgeons performing minimally invasive repairs must familiarize themselves with the potential complications in order to minimize the risk of unfavorable outcomes.

In a retrospective study using data from the American College of Surgeons (ACS) National Surgical Quality Improvement Program (NSQIP), Brungardt et al compared the outcomes of minimally invasive (Nuss) and open (Ravitch) repair in 168 patients aged 18 years or older with pectus excavatum as the postoperative diagnosis.[44] Median operating time was 250 minutes in the Ravitch group and 122 minutes in the Nuss group; median LOS was 5 days in the Ravitch group and 3 days in the Nuss group. Postoperative complication rates were similar in the two groups.

Patient instructions

All patients undergoing a Nuss procedure (minimally invasive repair of pectus excavatum [MIRPE]) should avoid all oral intake (nil per os [NPO]) for 12 hours before general anesthesia. Gentle bowel preparation with magnesium citrate might be of benefit in older patients, in that postoperative constipation is quite common after discharge from the hospital, primarily because the patients have taken large amounts of narcotics that will predispose them to constipation.

Elements of informed consent

The informed consent should include a discussion of the treatment options, including nonoperative management, minimally invasive repair, and open surgery.

Short- and long-term outcomes should be discussed with the patient and caregivers/parents. Risks, morbidity, and mortality must be addressed. Patients and families must understand that although MIRPE is considered minimally invasive, postoperative pain and discomfort can be significant because of the forceful bending of the sternum and cartilages.

The most common complication (bar displacement) and the possible need for reoperative surgery must be discussed. Although rare, the possibility of death must be discussed. Patients with an asymmetric pectus excavatum must be made aware that the asymmetry of the chest may continue despite successful repair of the caved-in sternum.

Laboratory evaluation

Preoperative laboratory testing is not necessary in healthy children. Postoperatively, a complete blood count (CBC) and metabolic panel on postoperative day 1 could be considered. If the laboratory values are normal and the patient has an uncomplicated postoperative recovery, additional laboratory evaluation is not necessary.

Selection and preparation of pectus bar

The chest is marked with a sterile marking pen in the deepest portion of the pectus (with care taken to ensure that it is not inferior to the sternum), on the corresponding intercostal spaces on the right and left sides where the bar is to be inserted, and on the points on the pectus ridge that correspond to the horizontal plane from the deepest point of the pectus to the lateral chest wall incisions. This provides the surgeon with visual information as to where the bar will be placed.

At this time, the length of the pectus bar to be placed is determined by using the marks made on the chest. A measurement should be made of the distance from the midaxillary line on one side to the opposite midaxillary line. The length of the bar is measured in inches; available sizes (see the image below) range from 7 in. (17.8 cm) to 17 in. (43.2 cm). The bar will be 0.4-0.8 in. (1-2 cm) shorter than the measured distance between the two midaxillary lines. A typical measurement for a teenage patient may be in the range of 12-15 in. (30-38 cm).

The bar is bent from the center out to either end, with small gradual bends made by using a bar bender. The curvature (convexity) of the bar is shaped to fit each individual patient's chest. Occasionally, slightly exaggerating the curvature to allow for the anterior chest-wall pressure that may alter the original configuration of the bar may be necessary. The bar must fit snugly over the chest. (See the image below.)

Special considerations

Scoliosis and pectus excavatum

An association between anterior chest-wall deformities and scoliosis has been described in the literature but is poorly defined. Apparently, only 4-5% of patients with severe anterior chest-wall deformities have scoliosis of sufficient magnitude to warrant evaluation by a spinal deformity physician.[1]

The relation between anterior chest-wall deformity and scoliosis is most clear in patients with Marfan syndrome.[45]  Patients with Marfan syndrome who have scoliosis are at high risk for progression of the deformity to unacceptable levels and have not historically responded well to brace therapy.[46]

Because of the association between pectus deformities and scoliosis, carefully examine patients with anterior chest-wall deformities for signs of scoliosis, and perform radiography if indicated. Patients younger than 5 years who present with spinal deformity are at risk for adverse cardiopulmonary sequelae related to the scoliosis. The management of scoliosis in patients with anterior chest-wall deformities follows the treatment principles outlined for patients with idiopathic scoliosis.

Pouter pigeon breast

This condition represents a rare congenital deformity of the chest characterized by a protrusion of the manubriosternal junction and adjacent costal cartilages, as well as premature sternal ossification (see the image below). One third of patients with pouter pigeon breast have concomitant depression of the lower sternum (pectus excavatum). Several cardiovascular abnormalities have been associated with premature sternal ossification, the most common being ventricular septal defect.[47]

Surgical correction includes the wide wedge transverse sternotomy at the angle of Louis and subperichondrial resection of the adjacent costal cartilages. Long-term outcomes are encouraging.

Poland syndrome

This syndrome is characterized by pectus excavatum, hypoplasia or absence of the breast or nipple, hypoplasia of subcutaneous tissue, absence of the costosternal portion of the pectoralis major, absence of the pectoralis minor, syndactyly or bony abnormalities of the forearm, and absence of costal cartilages or ribs (typically ribs 2-4 or 3-5).[48]  Clinical manifestations of Poland syndrome are highly variable, and all features rarely affect a single individual.[49]

Adult patients with pectus excavatum

During the era of open pectus excavatum repair, adult patients rarely underwent corrective surgery.[22]  However, with the introduction of MIRPE, surgeons noticed a significant change in the trend for corrective surgery in patients older than 18 years.[19]  Although MIRPE can be successfully performed in adults, these patients are at increased risk for bar displacement and other complications. In addition, they experience greater and more prolonged postoperative pain. For these reasons, some surgeons prefer the open technique.

Standard equipment for open and thoracoscopic surgery is necessary. A 5-mm blunt trocar is used for the thoracoscopy (5-mm 30° angled laparoscope/thoracoscope). Electrocautery is used to create the subcutaneous space necessary for performing the procedure (see technical description of the operation).

Pectus bar

The pectus bar was originally manufactured by the Lorenz Corporation, which subsequently became the Biomet Microfixation Company, with corporate headquarters located in Jacksonville, FL (part of Zimmer Biomet, located in Warsaw, IN). The Biomet Pectus Bar is available in various lengths, ranging from 7 in. (17.8 cm) to 17 in. (43.2 cm) to accommodate most patients undergoing correction of pectus excavatum. The Pectus Support Bar and stabilizers are made from stainless steel, ASTM F 138. The company recommends that the device be removed when remodeling of the chest wall is complete (usually after ~3 years).

Device sterilization and use

The company guidelines have stated the following: “Steam sterilize the Pectus Support Bar prior to implantation using steam sterilization equipment which has been properly validated. Following is a recommended minimum cycle for steam sterilization that has been validated by Biomet Microfixation under laboratory conditions. Individual users must validate the cleaning and autoclaving procedures used on-site, including the on-site validation of recommended minimum cycle parameters.” This requirements can be easily met in the hospital setting.

The company has also stated that “[s]urgical implants like the pectus bar should never be reused.” Although the implant may appear undamaged, it may have imperfections, defects, or internal stress patterns that may lead to breakage or inadequate performance.

Device-related adverse effects

Metal sensitivity reactions or allergic reaction to the implant material, though rare, have been reported (estimated incidence, < 1%). Metal allergy testing is recommended prior to surgery in patients with suspected metal allergy and/or hypersensitivity to metals.

Patients with a known history of metal allergy may require a titanium pectus bar for the repair. In such cases, the bar must be preordered from the manufacturer. The titanium bar should be prebent by the company in order to facilitate the surgical procedure. A preoperative computed tomography (CT) scan of the chest can be sent to the company to allow for prebending of the bar.

The manufacturer also states that device fracture, breakage, migration, or loosening is a possibility after implant placement.

A first-generation cephalosporin antibiotic (cefazolin) should be given 1 hour before surgery and continued for 24-48 hours.

Anesthesia

The combination of general endotracheal anesthesia and a thoracic epidural has been considered ideal. The epidural catheter is left in place for up to 3 days following the operation, providing excellent adjuvant therapy to pain management techniques. Ultrasound-guided erector spinae plane block may be a feasible and effective alternative to thoracic epidural analgesia for pain management after Nuss repair.[50]

An indwelling Foley catheter is placed because urinary retention is common with thoracic epidurals (30%). Hemodynamic monitoring by the anesthesiologist does not necessitate central venous or arterial lines.

Positioning

The patient is positioned in supine position in the operating room table with both arms out in order to allow ample access to the entire anterior and lateral chest. Avoiding hyperextension of the arms while the patient is in this position is important in order to avoid injury to the axillary nerve.

Intraoperative monitoring typically includes standard anesthetic monitoring and pulse oximetry. Placing an arterial line and/or central line for hemodynamic monitoring is not necessary. Given the presence of the thoracic epidural and the high use of postoperative narcotics, having patients monitored in a critical care unit (such as a pediatric intensive care unit [PICU] or stepdown unit) after the procedure might be necessary because of the risk of postoperative respiratory depression.

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.

Once at home, the patient may sleep in any position that is comfortable. Again, bending at the hip and slouching are discouraged, particularly in the first month. Regular activity is permitted as pain reduces and mobility increases. Heavy lifting is not permitted for 1 month after surgery.

A physical fitness program should be started 30 days after corrective surgery in order to promote healing and remodeling of the chest wall. Contact sports should be avoided for at least 6 months, particularly in older children and teenagers; a direct blow to the chest may predispose the patient to bar displacement.

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.

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).

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.

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).

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).

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.

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.

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]

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]

Class Summary

Induction of anesthesia is accomplished by using high doses of opioid. Pain control is essential to quality patient care. Analgesics ensure patient comfort, promote pulmonary toilet, and have sedating properties that are beneficial for patients who experience pain.

Morphine sulfate (Duramorph, Astramorph, MS Contin, Avinza, Kadian)

Morphine sulfate is the DOC for analgesia owing to its reliable and predictable effects, safety profile, and ease of reversibility with naloxone.

Various IV doses are used; it is commonly titrated until the desired effect is obtained.

Class Summary

NSAIDs have analgesic, anti-inflammatory, and antipyretic activities. Their mechanisms of action are unknown, but they may inhibit cyclooxygenase activity and prostaglandin synthesis. Other mechanisms may be present, such as inhibition of leukotriene synthesis, lysosomal enzyme release, lipoxygenase activity, neutrophil aggregation, and various cell membrane functions.

Naproxen (Anaprox, Naprelan, Aleve, Naprosyn)

Naproxen is used for relief of mild to moderate pain; it inhibits inflammatory reactions and pain by decreasing the activity of cyclooxygenase, which is responsible for prostaglandin synthesis.

Ibuprofen (Motrin, Advil, Addaprin, Caldolor )

Ibuprofen is the drug of choice for mild to moderate pain. It inhibits inflammatory reactions and pain by decreasing prostaglandin synthesis. Many doses are available, either with or without a prescription.

Ketoprofen

Ketoprofen is used for the relief of mild to moderate pain and inflammation. Small doses are indicated initially in patients with small body size, elderly patients, and persons with renal or liver disease. Doses of over 75 mg do not increase therapeutic effects. Administer high doses with caution, and closely observe the patient for response.

Flurbiprofen

Flurbiprofen may inhibit cyclooxygenase, thereby inhibiting prostaglandin biosynthesis. These effects may result in analgesic, antipyretic, and anti-inflammatory activities.

Diclofenac (Voltaren XR, Cataflam, Cambia)

This is one of a series of phenylacetic acids that has demonstrated anti-inflammatory and analgesic properties in pharmacological studies. It is believed to inhibit the enzyme cyclooxygenase, which is essential in the biosynthesis of prostaglandins. Diclofenac can cause hepatotoxicity; hence, liver enzymes should be monitored in the first 8 weeks of treatment. It is absorbed rapidly; metabolism occurs in the liver by demethylation, deacetylation, and glucuronide conjugation. The delayed-release, enteric-coated form is diclofenac sodium, and the immediate-release form is diclofenac potassium.

Tolmetin

Tolmetin inhibits prostaglandin synthesis by decreasing the activity of the enzyme cyclooxygenase, which in turn decreases formation of prostaglandin precursors. The pediatric dosage is 20 mg/kg/d PO divided tid/qid initially, then 15-30 mg/kg/d, not to exceed 30 mg/kg/d.

Celecoxib (Celebrex)

Celecoxib inhibits primarily COX-2. Inhibition of COX-1 may contribute to NSAID GI toxicity. At therapeutic concentrations, COX-1 isoenzyme is not inhibited; thus, incidence of GI toxicity, such as endoscopic peptic ulcers, bleeding ulcers, perforations, and obstructions, may be decreased when compared with nonselective NSAIDs.

Seek the lowest dose for each patient. The adult dosage is 100-200 mg PO bid; the pediatric dosage (which has not been established for patients younger than 2 years) is 50 mg PO bid for patients 2 years or older whose weight is ≥10 kg to ≤25 kg, and is 100 mg PO bid for patients 2 years or older whose weight is >25 kg.

Indomethacin (Indocin)

Indomethacin is used for relief of mild to moderate pain; it inhibits inflammatory reactions and pain by decreasing the activity of COX, which results in a decrease of prostaglandin synthesis.