Andre Bahoric

Congenital tracheal stenosis: A review of 22 patients from 1965 to 1987

Twenty-two infants with congenital tracheal stenosis (CTS) were treated in our hospital between 1965 and 1987. Diagnosis was confirmed by endoscopic and radiographic methods. Patients had a spectrum of tracheobronchial lesions from localized stenosis to more complex deformities involving the carina and bronchi. Other anomalies were found in all patients with the occurrence of vascular slings or rings in 11 patients (50%). Six infants treated nonoperatively died from severe CTS and other lethal anomalies. Five of 16 patients (31%) treated surgically survived. Localized CTS in four cases was treated by dilatation, tracheostomy, or tracheal resection with primary anastomosis (two survivors, 2 non-survivors). Funnel-shaped deformities and extensive tracheobroncial stenosis were treated by tracheal reconstruction using a variety of autogenous tissue and prosthetic grafts (three survivors, nine non-survivors). The overall mortality was 77%. A new intratracheal stent was used in two patients. The stent was a flexible steel spring covered with a silicone rubber sheath. In one patient, it was placed within the trachea at the time of repair and removed later with the bronchoscope. A stent was used in a second patient with intermittent airway obstruction following an esophageal tracheoplasty. In this case, the device failed to alleviate the obstruction, and the infant expired from progressive respiratory failure. Issues of importance in the management of infants with CTS are: (1) adequate evaluation of the tracheobronchial tree, (2) awareness that tracheobronchography may precipitate further respiratory decompensation, (3) assessment of vascular and other anomalies requiring surgical correction, and (4) selection of an appropriate therapeutic approach.

Long-term functional results of prosthetic airway splinting in tracheomalacia and bronchomalacia

The long-term functional results of splinting a collapsing major airway with a silastic Marlex mesh prosthesis were assessed. Six patients in whom follow-up has been longer than 4 years (mean 5.3 years) were studied. The prosthetic semirigid splints had been implanted in five children with tracheomalacia and one with bronchomalacia. Mean age at the time of airway splinting was 4 years (range 6 months to 8 years). At their last clinical evaluation, all six children were leading normal active lives. Three had mild respiratory symptoms not related to the splinting. The only long-term complication was a serous effusion that developed around the splint and compressed the trachea in one child 2 years postoperatively. Tracheal fluoroscopy, barium swallow, and computed tomography scans of the trachea in five patients demonstrated satisfactory tracheal caliber without airway collapse during expiration and coughing. Pulmonary function testing showed a mild increase in airway resistance in one child who had had a tracheostomy. These results demonstrate that the application of composite synthetic graft to a segment of a malacic airway in young patients can provide long-term relief from airway collapse without compromising airway growth.

A new intratracheal stent for tracheobronchial reconstruction: Experimental and clinical studies

An intraluminal tracheal stent (ITS) was used experimentally in rabbits and piglets, as well as clinically in infants with tracheal stenosis, to facilitate airway reconstruction. The ITSs were constructed of stainless-steel springs covered with silicone rubber. They were implanted in seven piglets (6 to 8 kg), five rabbits (3 to 5 kg) and three infants. No animals developed severe respiratory distress and all appeared to tolerate the ITS. Postmortem examinations 1 to 8 weeks after surgery showed (1) loss of stent fixation (one pig), (2) increased tracheal secretions, (3) pneumonia (one pig, two rabbits), and (4) focal squamous metaplasia of tracheal mucosa. Stents used to treat three infants (2 to 5 months of age) with complex tracheobronchial stenosis were placed at the time of periosteal tracheoplasty in two. Recurrent stenosis necessitated a second tracheoplasty and stenting in one, and a long tracheostomy tube and balloon dilatations in the other. The third child had endoscopic stent insertion to alleviate severe airway collapse after esophageal tracheoplasty. The child died from progressive respiratory failure after stent dislodgment. Although the stents were well tolerated in animals and they enhanced critical ventilation of all pulmonary lobes in infants after tracheal reconstruction, certain modifications such as alternative methods of fixation, accommodation for tracheal growth, and reduction in tissue reactivity are necessary before further use of the ITS can be advocated.

Treatment of segmental tracheomalacia and bronchomalacia by implantation of an airway splint

A silastic reinforced marlex mesh splint was inserted surgically to support a collapsing airway in 3 children with tracheomalacia and 1 with bronchomalacia. The operation was well tolerated and no complications occurred. The splint successfully eliminated symptoms of airway collapse in all children. Its effect on airway growth is not yet certain. This method is applicable to patients with tracheomalacia in whom vascular suspension does not eliminate collapse and for those with bronchomalacia in whom pulmonary resection might otherwise be necessary.

The successful reconstruction of thoracic tracheal defects with free periosteal grafts

A defect was created in the thoracic trachea in nine piglets (10 kg) by excising a segment from the entire thoracic trachea proximal to the right upper lobe bronchus (3 to 3.5 cm in length) and 30% of the circumference in width (1 to 1.5 cm). The defect was repaired with a free tibial periosteal graft (FPG) and in four piglets an omental pedicle graft (OPG) was applied to the surface of the FPG. An internal tracheal splint was inserted for 12 to 16 days to support the repair and prevent air leak. The splints were removed bronchoscopically. None of the pigs developed signs of airway obstruction at any stage following the repair. Eight were killed 3 months postoperatively when four to six times their original weight. One pig died on the 18th postoperative day of unknown cause. The tracheas were removed, x-rayed, and examined grossly and histologically. The results demonstrated normal tracheal growth with absence of either stenosis, collapse, or granulation tissue. All grafts were viable, bone formation was present, and the lumenal surfaces were lined with columnar and respiratory epithelium. The OPG did not improve vascularization of the FPG. This model suggests that tracheal stenosis in children may be surgically corrected by simply incising the stenotic segment longitudinally and enlarging the tracheal diameter by inserting a FPG into the defect.

Reduced tracheal growth after reconstruction with pericardium

Four groups of piglets were used to test the use of pericardium and periosteum as free grafts in the repair of full thickness cervical tracheal defects. Pericardium provided an airtight, rapidly healing graft, but did not give sufficient structural rigidity to prevent narrowing and growth failure at the graft site. Composite grafts of pericardium and periosteum were also unsatisfactory, in that the periosteum failed to produce enough bone to prevent collapse of the graft. Since previous studies have shown that periosteal grafts result in good bone formation when applied alone or as an extramucosal support, it is concluded that the osteogenic potential is dependent on the available blood supply and speed of revascularization. It appears that the presence of pericardium in the composite grafts may have inhibited this property.

Tracheomalacia: an experimental animal model for a new surgical approach.

Tracheomalacia was created by removing the posterior 50% of the circumference of eight cartilage rings (5-6 cm in length) from the intrathoracic trachea in each of 12 piglets while leaving the mucosa intact. In 6 animals an autologous, free tibial periosteal graft was applied over the defect (graft group). The remaining 6 piglets served as the control group. In all animals, a silastic stent was left in the trachea for 2 weeks to prevent immediate tracheal collapse. The presence of tracheomalacia was assessed 6-8 weeks after surgery. At bronchoscopy total tracheal collapse during coughing occurred only in the controls. As the animals went from quiet breathing to coughing, mean intrathoracic pressure increased from 5 to 80 cm H2O in both groups, and average sagittal tracheal diameter decreased by 10% in the graft group and 71% in the controls. During coughing, mean resistance to airflow across the defect increased by 0.005 +/- 0.002 cm H2O/liter/min in the graft group, by 0.083 +/- 0.96 cm H2O/liter/min in the controls (P less than 0.005), and by 0.027 cm H2O/liter/min at the same tracheal level in two normal pigs. At sacrifice 12 weeks postoperatively, bone and collagenized fibrous tissue had been produced by all grafts, without evidence of stricture. This study shows that experimentally induced tracheomalacia can be treated successfully by the application of an autologous periosteal tibial graft, which becomes incorporated into the weakened tracheal wall.

Effect of prosthetic airway splint on the growing trachea

Airway splints are now used clinically to treat tracheomalacia and may also have a place in the management of tracheal stenosis. These studies in 5 to 7 Kg piglets were designed to assess the effects of prosthetic airway splints on airway growth and to establish their usefulness in the reconstruction of tracheal defects. Three experimental groups were studied: group I (n = 8). Silastic reinforced Marlex mesh or Vicryl mesh prostheses were placed around 75% of the circumference of a 3 cm segment of trachea. Pigs were sacrificed at 4 months (average weight = 78.9 +/- 9.0 Kg) and the cross-sectional area of trachea was measured. Group II (n = 5). The same prostheses were used to replace the tracheal defect created by excising three rings (50% of tracheal circumference). Tracheas were examined grossly and histologically at sacrifice. Group III (n = 5). Same as Group II except tracheal defect covered by strap muscles. Prostheses placed external to them to prevent airway collapse. Group I had 4% to 14% (mean 8%) decrease from normal cross-sectional area of trachea at site of splint. No airway obstruction and no infection was encountered. Group II, severe airway obstruction, granulation tissue, and infection at site of defect was noted. Group III showed no signs of airway obstruction, no infection, and minimal airway narrowing. Re-epithelialization of the muscle surface in contact with airway occurred in all these animals. Silastic reinforced Marlex or Vicryl splints placed around the intact rapidly growing trachea do not significantly limit its growth. In addition, these synthetic materials appear to be well-tolerated when used to reconstruct tracheal defects if placed over well-vascularized tissue such as muscle.

Cryopreservation of pig trachea

A method of graft preservation is essential if tracheal allografts are to become an option in reconstructing long, circumferential defects. This study evaluated the effect of cryopreservation on tracheal grafts. Eight 6-ring tracheal segments obtained from sacrificed pigs were cryopreserved for 2 months at-196°C by a standard low-freezing technique. Once thawed, 5 were examined histologically (group A) and 3 were wrapped with omentum and then implanted in the peritoneum of a donor pig (group B). Grafts were examined 1 month later. In 10 piglets (group C), a 4-ring segment of cervical trachea was removed and the defect closed by primary anastomosis. The graft was cryopreserved for 7 days, thawed, then reimplanted by dividing the thoracic trachea and interposing the cryopreserved trachea wrapped with omentum. Three piglets developed respiratory distress and were killed after 7 to 20 days; the remaining 7 were killed after 1 month. The grafts were rigid in groups A and B. Chondrocytes were present in group A, but in group B ghost cells were noted. Group C grafts were less rigid than the normal trachea although they did not collapse. Microscopically, cartilage had been replaced by fibrous tissue. Cryopreservation failed to maintain the viability of chondrocytes. However, the resulting fibrous trachea may prove to be a satisfactory alternative for replacement of longitudinal defects such as those created by tracheoplasty to treat congenital tracheal stenosis.

Evaluation of a new catheter for total parenteral nutrition.

Central venous catheters play an important role in the management of children with a variety of disorders. Desirable characteristics of such catheters include case and reliability of placement, secure fixation, low rates of complication, and ease of removal. We describe our experience with a new form of catheter that displays all of these characteristics. One hundred twenty-nine catheters were inserted in III paients over a 2-year period for a total of 5.729 treatment days. This catheter is made of silicone rubber and is positioned by using P-wave changes seen during intraoperative electrocardiography. x-Ray confirmation is not routinely necessary. The catheter is fixed in position by use of a grommet, which is sutured in the neck at the site of the venotomy. This form of fixation allows the catheter to be casily in position for the duratio of use. Our experience with this catheter has been associated with a low incidence of septic (1.1–4.2 septic episodes per 1.000 patient days) and mechanical (2.3 episodes per 1,000 patient days) complications in a setting that includes both in-hospital and home total parenteral nutrition patients. It is felt that this new form of eatheter and catheter fixation offers several advantages over other types of central venous catheters currently in use.