Patient Education and Consent
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.
Preprocedural Planning
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]
Patient with pouter pigeon breast. Note protrusion of manubriosternal junction and adjacent costal cartilages with S-shaped appearance of sternum.
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.
Equipment
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.
Patient Preparation
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.
Monitoring & Follow-up
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.
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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.
