I. Overview
Pectus excavatum (PE) accounts for more than 90% of pediatric thoracic skeletal deformities, with an incidence of 0.1% to 0.3% and a male-to-female ratio of 4:1. 90% of cases are detected within the first year of life, which seriously affects the physical and mental health of the affected children. The cause of the disease is still unclear, and it is thought to be a familial disease with autosomal dominant inheritance. In severe cases, the sunken sternum compresses the heart and lungs and affects the respiratory and circulatory functions, resulting in reduced lung capacity, breathing difficulties, and recurrent respiratory infections.
The traditional method of correction of funnel chest is the sternal elevation method and its modification founded by Ravitch in 1949. Its disadvantages are large incision, trauma, bleeding, slow recovery, easy damage to pleura, lung and pericardium, easy postoperative complications such as pneumothorax, pleural effusion, pneumonia, pulmonary atelectasis, wound infection, steel pin breakage, displacement and even pericardial heart injury, as well as complicated postoperative care and high recurrence rate.
Dr. Donald Nuss, USA, observed three facts from his long-term clinical practice.
(1) The thorax of children is soft and elastic;
(2) In adults, the bones are calcified and mature, but the thorax of middle-aged and elderly patients with chronic emphysema disease can still be deformed and remodeled into a barrel-shaped chest;
(3) Bone has the property of being orthopedic, while cartilage is more suitable for this treatment. Therefore, from 1987, Dr. Donald Nuss proposed to place a special plate directly behind the sternum through the anterior chest wall to support and elevate the sternum based on the principle that the thorax can be reshaped by external forces, thus creating a minimally invasive surgical treatment method without removing the rib cartilage and without sternal osteotomy. In 1998, the results of 42 cases were first reported in the American Journal of Pediatric Surgery. This surgical method has the advantages of minimal trauma, good results, and cosmetic appearance, and has brought the treatment of funnel chest into the minimally invasive era, which is a revolutionary innovation in the history of funnel chest correction and is known as NUSS surgery or minimally invasive funnel chest orthopedic surgery, and is soon being widely performed all over the world.
The Nuss procedure has distinct advantages over the traditional Ravitch procedure in that.
(1) No surgical scars on the anterior chest wall, which has extraordinary aesthetic advantages;
(2) No free skin muscle flap, less bleeding;
(3) Less surgical trauma, no need to remove rib cartilage;
(4)The integrity of the thorax exists, and long postoperative ventilator-assisted breathing is not required;
(5)The operation time is short, and the operation is relatively simple;
(6) Fast recovery after surgery, early freedom of movement, can be discharged from the hospital 3 d after surgery, 6-8 d after surgery, short hospitalization time;
(7) Low recurrence rate.
II. Indications for Nuss surgery.
The age span of children undergoing NUSS surgery has been reported by NUSS surgeons to be up to 1-50 years old. However, the age of 6-12 years is considered to be the best time for NUSS surgery to correct funnel chest. This is because of the significant thoracic deformity in this age group and the significant results after correction. Early surgical correction of funnel chest can not only improve the appearance of chest wall deformity and correct the inferiority complex of the child, but also eliminate the impact on respiratory and circulatory functions at an early age and avoid the aggravation of symptoms of cardiopulmonary impairment in adulthood. In children younger than 6 years old, postoperative management is not easy and there are more accidents and injuries, and the recurrence rate is high because the skeleton is still in a high growth period at the age of children. 12 years old or older children will have longer operation time, more bleeding and more complications because of the increase of bony components of the rib arch and the poor compliance of the thorax. Moreover, if symmetric funnel chest is not corrected in childhood, it may change to asymmetric after 12 years of age. Therefore, 6-12 years old is the best time for NUSS surgery to correct funnel chest.
The indications for NUSS surgery are: the child should meet 2 or more of the following conditions.
1, symptoms ;
2. Progressive worsening of the deformity;
3. Paradoxical movement of the chest wall during deep breathing;
4, CT examination Haller index > 3.25;
5.Cardiac ultrasound or chest CT indicates cardiopulmonary compression, heart displacement;
6, Mitral valve prolapse, bundle branch block or other arrhythmias secondary to cardiac compression;
7.Children with recurrence after NUSS surgery;
8.Disease causing psychological disorders in the child.
II. Nuss surgery steps and points.
1, preoperative preparation: measurement of the transverse thoracic diameter and funnel index, assessment of the degree of depression [11]. Accordingly, a suitable support plate (special plate) is selected and bent into an “arch” shape. The curvature is consistent with the preset lifting height. If there is nickel allergy, a titanium plate is used [12].
2. Anesthesia and position: general anesthesia with tracheal intubation, supine position, with arms abducted and anterior chest and bilateral axillae fully exposed.
3.Selecting the support point and the entry and exit points of the support plate: mark the lowest point of the sternal depression with US blue, and use this lowest point or slightly above it as the support point of the support plate. Select the appropriate rib gap at the highest point of the funnel crest on both sides of the same plane of the lowest point as the entry and exit points of the supporting steel plate, and mark them with US blue.
4.Select the incision: select the incision at the mid-axillary line position at the same level of the lowest point of the sternal depression and mark it with US blue.
5.Support plate reshaping: After laying the towel, place the above-designed support plate on the child’s thorax and estimate the support effect of the support plate. If the estimated support effect is unsatisfactory, the support steel plate will be readjusted with a bender to make it properly reshaped to achieve the most perfect support effect.
6.Production of tunnel and insertion of guide: make an incision of about 1.5-2cm in length at the intended incision, and separate the subcutaneous tissue and muscle layer along both sides of the thorax from outside to inside horizontally until the intended support steel plate enters the thoracic cavity to complete the production of bilateral subcutaneous tunnels. The thoracoscope was placed 2 rib spaces below the right side incision. The guide is inserted through the right subcutaneous tunnel to the predetermined support plate into the right thoracic cavity, and stabbed into the right thoracic cavity under the direct view of the thoracoscope, and slowly passes through the lowest point of the sternal depression closely to the left predetermined support plate out of the thoracic cavity, and finally reaches the contralateral incision through the subcutaneous tunnel.
7.Preliminary assessment of thoracic lift by the guide: At this time, the thoracic lift can be initially assessed by the guide, and the rib gap position can be adjusted accordingly until the optimal rib gap is found.
8.Insertion of the steel plate: The supporting steel plate is firmly fixed to the guide with a thick wire. Under thoracoscopic surveillance, the guide is pulled so that the support plate is pulled out from left to right through the left subcutaneous tunnel, the posterior sternal tunnel, and the right subcutaneous tunnel from the arch back down to the right incision, respectively.
9.Flipping: After the support plate is in place, the special flipper flips the support plate so that it is bowed back up and supported behind the sternum to lift the depressed thorax to the desired shape.
10.Fixation: The right end of the support plate is placed into the fixation piece to make a “T” shape, and the fixation piece is sutured and fixed to the periosteum of the rib and the adjacent muscle tissue. The left end of the support plate was sewn to the periosteum of the rib cage.
11.Exhaust, dial out the thoracoscope and close the incision: observe under the thoracoscope to make sure there is no obvious bleeding. Connect the mirror sheath ventilator with a water-sealed tube, and dial out the mirror sheath after the anesthesiologist performs lung expansion (PEEP 4~5cmH2O) chest venting. The subcutaneous tissue was sutured and intracutaneous sutures were made. The operating room was photographed to observe lung expansion and the presence of pneumothorax.
12.Postoperative treatment Antibiotic treatment was given for 2 days starting from the day of surgery. Routine pain relief treatment for 2-4 days after surgery. Keep lying down for 2 days. Discharge from hospital 5-7 days after surgery. The stent is instructed to be removed after 2~4 years.
IV. Evaluation of the efficacy of NUSS surgery
According to the report of Croitoru and Nuss et al. in 2002, the efficacy evaluation criteria were divided into three grades. Excellent: the appearance of the thorax is full, the child and parents are satisfied, and the clinical symptoms and signs disappear. Good: the appearance of the thorax improved, and the clinical symptoms and signs improved. Poor: recurrence of funnel chest, symptoms do not disappear, or need to operate again after removal of the supporting plate.
However, there are still different efficacy assessment criteria in China. Zeng Ti et al. considered the following conditions for surgical outcome assessment.
(1) Chest X-ray showing sternal changes;
(2) the effect of thoracic appearance;
(3) satisfaction of the patient and family;
(4) The degree of fullness, extension and elasticity of the thorax. Those who met 4 items were considered excellent; 3 items were considered good; 2 items were considered medium; 0-1 items were considered poor. Lu Yanan et al. reported four grades of orthopedic effect. Excellent: symmetrical correction was achieved without residual sternal depression. Good: symmetric correction was achieved or not, and the degree of residual sternal depression was less than 20% before surgery. Fair: the degree of residual sternal depression was 20%-50% of the preoperative degree. Poor: the degree of residual sternal depression is greater than 50% of the preoperative degree.
V. Complications of Nuss surgery and prevention matters.
Complications after Nuss surgery, which are reported to be as high as 21-67% in the literature, mainly include pneumothorax, displacement of fixator and plate, pericardial effusion, pleural effusion, cardiac injury, intrathoracic artery pseudoangioma, incisional infection, metal allergy, pneumonia, pleurisy, etc.
The most perceived complications of NUSS surgery are pneumothorax and subcutaneous emphysema, which are mostly due to the thin chest wall of the child, wound leakage, and crying of the child. After the operation, the closed chest drainage should be kept open, and the closed chest drainage can be removed if the chest X-ray shows no pneumothorax 48h after the operation. In addition, placing oil gauze around the drainage tube and at the wound can also effectively prevent the occurrence of pneumothorax and subcutaneous emphysema.
Cardiac injury, although very rare, is a serious intraoperative complication. It is mainly caused by early inexperience, unskilled surgical technique, poor shaping and fixation of the plate. Thoracoscopic surveillance was not routinely used for NUSS surgery, but for safety reasons, such as avoiding intraoperative cardiac penetrating injuries, thoracoscopic surveillance is now preferred to avoid intraoperative cardiac injury and injury to the thoracic arteries.
Displacement of the steel plate is the most common cause of reoperation, including left-right movement, up-down rotation, and backward plunging. The incidence was reported to be 15.7% in the early foreign literature and decreased to 5.4% after the application of fixators. It is important to choose the appropriate length of plate, plate support points, and fixation method to the chest wall. Generally, the length of the plate should be 1-2 cm shorter than the distance between the mid-axillary line on both sides, because the path of plate placement is shorter than the actual measured distance. To avoid postoperative displacement of the plate, it is important to choose a suitable plate support point during the operation. For a large depression area with a flat bottom, the support point can be chosen at the bottom of the funnel. For patients with smaller funnel area and deeper funnel, there should be a flat area of about 3cm in the middle of the plate when the plate is bent, and the middle of the flat area is slightly depressed, so that the contact area with the sternum increases after the plate is turned over, thus increasing the stability. Some foreign scholars have taken some improvement measures to reduce the incidence of plate displacement, such as Hebra’s “3-point method” for fixing the plate, and Uemura’s use of stainless steel wire to tie the plate directly to the ribs to prevent the displacement of the supporting plate.
The Nuss procedure requires attention to.
(1) Nuss surgery with the assistance of thoracoscopy is safer and more reliable. There are reports of damage to the heart and pericardium when Nuss surgery is not performed under thoracoscopic surveillance.
(2) The brace must be strong enough to maintain thoracic correction and placement for 2 years or longer.
(3) The support frame must be absolutely securely fixed to ensure that it does not shift or slip out of position after surgery.
(4) ) The point of support should be chosen at the lowest point of the sternal depression or the flat posterior part of the sternum on it as far as possible. If there is no sternal bony structure at the most depressed point or the posterior sternum is not flat, the support plate can be adjusted upward to the position where the sternal bony structure is flat to ensure the stability of the support plate. If the support plate is supported in the plane of the sternal process which is more elastic, it will easily lead to the displacement of the support plate.
(5) Pay attention to postoperative pain management, apply intravenous pump for pain relief at an early stage and psychological or even oral pain medication for children at a later stage, especially for older children, to prevent complications such as scoliosis or brace displacement.
(6) In postoperative recurrent cases of funnel chest, due to posterior sternal adhesions and unclear anatomical gaps, the guide should be tightly attached to the sternum when separating the posterior sternal gaps to avoid heart and pericardial injury.
(7) Postoperative guidance is very important. Patients should maintain a supine sleeping position and wear an orthopedic undershirt after getting out of bed to maintain an upright chest and straight back posture. Do not bend, twist or roll for the first 6 weeks after discharge from the hospital. Avoid strenuous sports for 2 years after surgery to avoid displacement of the plate
Postoperative management of Nuss.
1, pain management: postoperative pain is the most common and should be actively managed, otherwise it may lead to acquired scoliosis. Commonly used methods are: intravenous analgesic pump, oral painkillers, pain suppositories anal, etc. More scholars advocate continuous epidural analgesia; intraoperative intercostal nerve block anesthesia can also be performed. 2, strengthen respiratory management: nebulized inhalation, expectoration and other treatments are feasible, and children are encouraged to blow up balloons to prevent complications such as pneumonia and pulmonary atelectasis.
3.Postoperative anti-infection treatment.
4.Some patients may have symptoms such as abdominal distension, abdominal pain or constipation, which may be related to the extrusion of intercostal nerve by steel plates or the use of analgesics, and can be treated symptomatically after excluding abdominal conditions.
5.After surgery, try to keep chest up and shoulders horizontal posture, do not bend and carry heavy objects and do not do twisting and other movements within 2 months, avoid strenuous and confrontational movements within 3 months; strengthen supervision for younger children to prevent accidental injury from dislocation and fracture of the steel plate.
6.Take out the plate 2-4 years after surgery, and avoid MRI examination before taking out.
Nuss surgery is a revolutionary innovation in the history of funnel chest correction. It is worth promoting because of its minimally invasive and cosmetic features and good near and long term results.