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Biomedical subjects

L J Howell

Publications and source records attributed to L J Howell.

At least 19 recordsLinked to original sources

The management of prenatally diagnosed choledochal cysts.

BACKGROUND: Although congenital biliary tree abnormalities are uncommon in the United States, more are being diagnosed antenatally with improved imaging techniques. METHODS: To determine the prognosis of prenatally diagnosed biliary disease, the authors reviewed the treatment of 3 children who had biliary cystic lesions found during routine prenatal ultrasonography. RESULTS: All 3 children were born at term. They had elevated bilirubin levels, and postnatal ultrasound scans confirmed the presence of a biliary cystic mass. They underwent exploration within 2 weeks of life. At operation, 2 children were found to have biliary atresia with a cystic biliary lesion. They underwent Kasai procedures and are doing well at 5 and 9 months of age. The third child was found to have a type I choledochal cyst and malrotation at exploration. He underwent cystectomy with Roux-en-Y hepaticojejunostomy and a Ladd's procedure and is doing well at 3 years of age. CONCLUSIONS: Prenatally diagnosed biliary cysts represent a different spectrum of disease than those diagnosed later in life. The sequelae of biliary disease start before birth, and early operation may be necessary to achieve a good outcome. Because it is impossible to distinguish between choledochal cysts and biliary atresia on antenatal ultrasound scan or magnetic resonance imaging, children with presumed choledochal cysts should undergo early exploration to rule out potential biliary atresia. Excellent outcome is possible with early operation in the absence of severe associated anomalies.

Biliary Atresia↗

Echocardiographic evaluation of the fetus with congenital cystic adenomatoid malformation.

OBJECTIVES: The development of nonimmune hydrops is a known complication of congenital cystic adenomatoid malformation (CCAM) in the fetus. The aim of this study was to investigate the impact of CCAM on hemodynamics in the fetus and to determine whether cardiac dysfunction contributes to the development of hydrops in this patient population. METHODS: The echocardiographic data from 41 consecutive fetuses diagnosed prenatally with CCAM were reviewed. The presence or absence of hydrops was noted in each patient. Two-dimensional ultrasonographic and Doppler data were compared between the two groups (with or without hydrops). RESULTS: The mean gestational age for the study group at the time of imaging was 23.2 +/- 3.0 weeks. Hydrops was noted in 15 of 41 fetuses (36.5%). The fetuses that developed hydrops had a lower cardiac/thoracic ratio than those which did not develop hydrops (0.18 vs. 0.23, P = 0.001). The fetuses with hydrops also demonstrated an increase in early ventricular filling. The ratio of early ventricular filling to atrial contraction (E/A ratio) at both the tricuspid and mitral valves was significantly higher in the fetuses with hydrops (P = 0.005 and P = 0.03, respectively). Doppler interrogation of the inferior vena cava demonstrated a greater degree of reversal with atrial contraction in the hydrops group (29.7% vs. 15.1%, P = 0.003). The development of significant atrioventricular valve insufficiency was rare in the fetuses with hydrops (one of 15 cases). CONCLUSIONS: Cystic adenomatoid malformation can result in significant cardiac compression in the fetus. This alters hemodynamics and may result in hydrops on the basis of elevated central venous pressure.

Case-Control Studies↗

Treatment of severe congenital diaphragmatic hernia by fetal tracheal occlusion: clinical experience with fifteen cases.

OBJECTIVE: Our purpose was to determine whether prenatal tracheal occlusion improves survival in a selected population of fetuses affected by severe congenital diaphragmatic hernia. STUDY DESIGN: Fetuses with isolated congenital diaphragmatic hernia were selected as candidates for fetal intervention by specific criteria designed to predict a 90% mortality rate with conventional postnatal treatment. RESULTS: Fifteen fetuses underwent tracheal occlusion with 5 survivors (33%). Two fetuses were lost to early preterm labor. In 13 mothers, postoperative gestation ranged from 19 to 68 days, with a mean duration of pregnancy after tracheal occlusion of 38 days. The 5 survivors were hospitalized for an average of 76 days. Despite dramatic lung growth in some fetuses after tracheal occlusion, intensive management was required, and most deaths were caused by respiratory insufficiency. CONCLUSION: Prenatal tracheal occlusion can result in impressive lung growth in a subset of fetuses with severe congenital diaphragmatic hernia. However, survival remains compromised by pulmonary functional abnormality and the consequences of prematurity.

Child Development↗

Assessment of fetal lung volumes and liver herniation with magnetic resonance imaging in congenital diaphragmatic hernia.

OBJECTIVE: We evaluated the use of fetal magnetic resonance imaging in predicting outcomes after ultrasonographic diagnosis of left-sided congenital diaphragmatic hernia. STUDY DESIGN: Forty-one pregnant women carrying fetuses with congenital diaphragmatic hernia underwent 43 magnetic resonance imaging scans. Lung volumes were calculated by summing the areas on 6-mm axial sections. The presence or absence of liver herniation was noted. A liver/diaphragm ratio was obtained by using the distances from the superior aspect of the liver and the diaphragmatic remnant to the apex of the chest. RESULTS: Mean gestational age was 26 weeks and overall survival was 59%. Neither right, left, nor total lung volume measurements were predictive of survival. Liver herniation into the left side of the chest was predictive of outcome at P<.05. The liver/diaphragm ratio was predictive of outcome at P = .03. CONCLUSION: Fetal magnetic resonance imaging permits calculation of lung volumes, but these volumes are not predictive of outcome. However, both the presence of liver herniation and the volume of liver within the chest, as reflected by the liver/diaphragm ratio, help predict outcome in left-sided congenital diaphragmatic hernia.

Fetus↗

The essentials of a fetal therapy center.

Consensus about complex clinical decisions among specialists with diverse backgrounds will always be a challenge. A specialized center, which focuses on the fetus with an anomaly, provides the most accurate diagnosis and maternal-fetal management recommendations to referring physicians. The essential components of a fetal therapy center facilitate a systematic approach for the mother carrying a fetus with an anatomic malformation.

Female↗

Prenatal MRI evaluation of congenital diaphragmatic hernia.

The objective of this paper is to evaluate the efficacy of various magnetic resonance imaging (MRI) sequences and the general usefulness of prenatal MRI in determining the position of the fetal liver and visualizing lung tissue in fetuses who have congenital diaphragmatic hernia (CDH). This was a retrospective review of prenatal MRI of fetuses with a confirmed diagnosis by surgery or autopsy of CDH. MRI was performed in a 1.5-Tesla magnet using fast gradient echo, half-Fourier single-shot turbo spin-echo (HASTE) and echo planar images. The presence of a chest mass, position of the stomach and liver and visualization of the lungs by MRI was noted in all fetuses. This was compared to ultrasound studies performed the same day and correlated with postnatal or autopsy studies. The fetuses were 18-36 weeks gestational age (mean 24.5 weeks). MRI diagnosed left CDH (33), right CDH (4), and bilateral CDH (1) and agreed with the postnatal diagnosis in all patients. Ultrasound (US) diagnosed left CDH (33), right CDH (2), and congenital cystic adenomatoid malformation (3). MRI changed the diagnosis in four patients. The fetal liver was easily demonstrated with MRI in all fetuses and was herniated into the chest in 25 of the 38. US diagnosed liver up in 21. Correlation with postnatal studies found MRI correctly diagnosed liver position in 37 out of 38 cases. US correctly diagnosed liver position in 32 out of 38. Both lungs could be visualized in all fetuses with MRI. MRI accurately and easily diagnoses CDH and can differentiate it from other chest masses. MRI was superior to US in demonstrating the position of the fetal liver above or below the diaphragm. MRI reliably visualized fetal lung tissue. These findings are important for counseling parents, selecting fetal surgical candidates, and estimating prognosis.

Adult↗

Congenital chest lesions: diagnosis and characterization with prenatal MR imaging.

PURPOSE: To evaluate prenatal magnetic resonance (MR) imaging for diagnosis of fetal chest masses and to determine if MR imaging provides information in addition to that of ultrasonography (US). MATERIALS AND METHODS: Eighteen pregnant women were referred for MR imaging of possible fetal chest tumors seen at US (16 congenital cystic adenomatoid malformation [CCAM], two bronchopulmonary sequestration [BPS]). The presence, position, size, and characteristics of masses were determined and correlated with postnatal results. RESULTS: The MR imaging diagnoses were three cases of congenital diaphragmatic hernia, nine of CCAM, two of BPS, and one each of foregut cyst, lung atresia, tracheal atresia, and bronchial stenosis. MR imaging results were in agreement with US results in nine fetuses and in disagreement in nine. MR imaging diagnoses were confirmed at surgery or autopsy in 17 fetuses. MR imaging results led to an error in diagnosis in one fetus with BPS. CONCLUSION: Fetal chest masses had characteristic MR imaging appearances. MR imaging was accurate for distinguishing congenital diaphragmatic hernia from CCAM and was useful for less common diagnoses and determination of the origin of very large chest tumors. Prenatal diagnosis was changed in some patients owing to MR results and affected treatment and counseling of parents. MR imaging is a valuable adjunct to US for prenatal diagnosis of fetal chest masses.

Bronchopulmonary Sequestration↗

Fetal lung lesions: management and outcome.

OBJECTIVE: Our purpose was to review our experience with fetal congenital cystic adenomatoid malformation and extralobar pulmonary sequestration emphasizing natural history, management, and outcome. STUDY DESIGN: We conducted a retrospective review of 175 fetal lung lesions diagnosed by antenatal ultrasonography at 2 fetal treatment centers. RESULTS: There were 134 congenital cystic adenomatoid malformation cases. Fourteen women underwent elective abortion, 101 women were managed expectantly, 13 women had fetal surgery, and 6 women had placement of a thoracoamniotic shunt. For the congenital cystic adenomatoid malformation lesions that were not associated with nonimmune hydrops, all babies survived. Of 25 large congenital cystic adenomatoid malformations that had associated hydrops that were followed expectantly, all fetuses died before or shortly after birth. Fetal surgical resection of the tumor (fetal lobectomy) was performed at 21 to 29 weeks' gestation in 13 hydropic fetuses with 8 fetuses continuing gestation with subsequent hydrops resolution, impressive in utero lung growth, and neonatal survival. Six fetuses with a very large solitary cyst underwent thoracoamniotic shunting and 5 survived. There were 41 extralobar pulmonary sequestration cases. Twenty-eight extralobar pulmonary sequestrations dramatically regressed on serial prenatal sonography, were asymptomatic after birth, and were only detectable by imaging studies postnatally (no resection required). Of the remaining 13 extralobar pulmonary sequestration cases, 2 underwent elective abortion, 7 symptomatic lesions were resected after birth with survival, 1 hydropic fetus died, and 3 fetuses had an associated tension hydrothorax with secondary hydrops that was successfully treated by either fetal thoracenteses or thoracoamniotic shunting followed by postnatal resection. CONCLUSIONS: The natural history of prenatally diagnosed lung masses is variable, and associated anomalies are rare. Most congenital cystic adenomatoid malformation lesions can be managed with maternal transport, planned term delivery, and postnatal resection. Many extralobar pulmonary sequestrations dramatically decrease in size before birth and may not need treatment after birth. Fetal therapy is now an option for lung lesions associated with nonimmune hydrops.

Amnion↗

Cystic lung lesions with systemic arterial blood supply: a hybrid of congenital cystic adenomatoid malformation and bronchopulmonary sequestration.

Congenital cystic adenomatoid malformation and bronchopulmonary sequestration are congenital lung tumors that are classically described as having distinct embryology, pathology, and natural history. The authors treated six patients who had prenatally diagnosed lung masses that displayed clinicopathologic features of both lesion types. At prenatal diagnosis (19 to 30 weeks' gestation), all six lesions were classified sonographically as congenital cystic adenomatoid malformation, and none of the masses appeared to have a systemic arterial blood supply as seen by color flow Doppler study. Two of the six masses showed size regression antenatally. At the time of surgery, all six lesions had a systemic vessel directly from the aorta--five cases were consistent grossly with an intralobular bronchopulmonary sequestration, and one case was consistent with an extralobular bronchopulmonary sequestration. However, all six lesions displayed congenital cystic adenomatoid malformation histology. Hydrops developed in one fetus with a huge mass, and that fetus underwent successful fetal surgical resection (left lower lobectomy) at 22 weeks' gestation with delivery at 35 weeks' gestation. One neonate with a large extralobular bronchopulmonary sequestration was treated with resection and extracorporeal membrane oxygenation (ECMO) but died of pulmonary hypoplasia. Four other patients who had much smaller masses underwent elective lower lobectomy after birth. These findings emphasize the importance of seeking an anomalous blood supply in patients who have congenital lung lesions. These "hybrid" cases suggest a similar embryological origin for congenital cystic adenomatoid malformation and bronchopulmonary sequestration.

Abnormalities, Multiple↗

Correction of congenital diaphragmatic hernia in utero VII: a prospective trial.

BACKGROUND: Congenital diaphragmatic hernia (CDH) remains an unsolved problem. Despite optimal postnatal care, up to 60% of CDH babies die. Experimental evidence and clinical experience have shown that in utero repair of CDH is feasible and can reverse pulmonary hypoplasia, but only in fetuses without liver herniation. For this subgroup, the safety and efficacy of repair before birth has not been compared with standard care after birth. METHODS: Four fetuses in whom CDH without liver herniation was diagnosed underwent open fetal surgery for repair of the CDH. Seven comparison fetuses were treated conventionally. Neonatal mortality was the principle outcome variable. Secondary outcome variables included death of all causes until 2 years of age, number of days of ventilatory support, length of hospital stay, requirement for extracorporeal membrane oxygenation (ECMO), and total hospital charges. RESULTS: There was no difference in survival between the fetal surgery group and the postnatally treated comparison group (75% v 86%). Fetal surgery patients were born more prematurely than the comparison group (32 weeks v 38 weeks' gestation). Length of ventilatory support and requirement for ECMO were equivalent in the fetal surgery group and the postnatally treated comparison group. Length of hospital stay and hospital charges did not differ between the groups. CONCLUSIONS: Open fetal surgery is physiologically sound and technically feasible, but does not improve survival over standard postnatal treatment in the subgroup of CDH fetuses without liver herniation, primarily because overall survival in this subgroup is favorable with or without prenatal intervention. These data suggest that fetuses who have prenatally diagnosed CDH and without evidence of liver herniation should be treated postnatally.

California↗

Correction of congenital diaphragmatic hernia in utero VIII: Response of the hypoplastic lung to tracheal occlusion.

Most fetuses with congenital diaphragmatic hernia (CDH) diagnosed before 24 weeks' gestation die despite optimal postnatal care. In fetuses with liver herniation into the chest, prenatal repair has not been successful. In the course of exploring the pathophysiology of CDH and its repair in fetal lambs, the authors found that obstructing the normal egress of fetal lung fluid enlarges developing fetal lungs, reduces the herniated viscera, and accelerates lung growth, resulting in improved pulmonary function after birth. They developed and tested experimentally a variety of methods to temporarily occlude the fetal trachea, allow fetal lung growth, and reverse the obstruction at birth. The authors applied this strategy of temporary tracheal occlusion in eight human fetuses with CDH and liver herniation at 25 to 28 weeks' gestation. With ongoing experimental and clinical experience, the technique of tracheal occlusion evolved from an internal plug (two patients) to an external clip (six patients), and a technique was developed for unplugging the trachea at the time of birth (Ex Utero Intrapartum Tracheoplasty [EXIT]). Two fetuses had a foam plug placed inside the trachea. The first showed dramatic lung growth in utero and survived; the second (who had a smaller plug to avoid tracheomalacia) showed no demonstrable lung growth and died at birth. Two fetuses had external spring-loaded aneurysm clips placed on the trachea; one was aborted due to tocolytic failure, and the other showed no lung growth (presumed leak) and died 3 months after birth. Four fetuses had metal clips placed on the trachea. All showed dramatic lung growth in utero, with reversal of pulmonary hypoplasia documented after birth. However, all died of nonpulmonary causes. Temporary occlusion of the fetal trachea accelerates fetal lung growth and ameliorates the often fatal pulmonary hypoplasia associated with severe CDH. Although the strategy is physiologically sound and technically feasible, complications encountered during the evolution of these techniques have limited the survival rate. Further evolution of this technique is required before it can be recommended as therapy for fetal pulmonary hypoplasia.

Animals↗

Fetal diaphragmatic hernia without visceral herniation.

Many cases of congenital diaphragmatic hernia (CDH) are currently detected before birth. The authors hypothesized that there is a subgroup of patients with CDH who have no evidence of visceral herniation in utero and who would be expected to have less pulmonary hypoplasia and a good prognosis. Among 41 neonates with left-sided CDH treated between January 1990 and October 1993, 17 cases were diagnosed after birth. Ten of the 17 had undergone detailed fetal sonographic imaging at or after 20 weeks' gestation. After independent review of the prenatal scans of these 10 patients, one was found to have evidence of a diaphragmatic hernia and was excluded from further analysis. The other nine fetuses survived, and prosthetic repair of the diaphragmatic defect and extracorporeal membrane oxygenation (ECMO) were each required in only one patient. This contrasted with the outcome for 18 control patients with prenatally diagnosed CDH: 4 (22%) died, 13 (72%) required prosthetic repair, 9 (50%) were supported with ECMO and the duration of ventilatory support and hospital stay were significantly longer. There is a spectrum of severity among both pre and postnatally diagnosed cases of CDH. In the neonate with an isolated left-sided diaphragmatic hernia, a good prognosis is to be expected if the condition was not detectable by detailed prenatal sonography in the second half of pregnancy.

Female↗

A prospective study of the outcome for fetuses with diaphragmatic hernia.

OBJECTIVE: To establish the natural history and outcome of isolated congenital diaphragmatic hernia (CDH) diagnosed before birth. The mortality of CDH with currently available postnatal care, including extracorporeal membrane oxygenation (ECMO), reported in retrospective studies ranges from less than 25% to greater than 75%. This variation is attributable to a "hidden mortality" (infants who die with CDH that is not recognized) of unknown magnitude. DESIGN: Prospectively followed case series. SETTING: Patients were referred from practitioners in 18 states and evaluated and followed up by the University of California, San Francisco, Fetal Treatment Center. Arrangements were made for planned delivery at tertiary perinatal centers with ECMO capability. PATIENTS: All 83 fetuses with isolated, potentially correctable CDH diagnosed prior to 24 weeks' gestation referred to the University of California, San Francisco, Fetal Treatment Center between January 1989 and October 1993. MAIN OUTCOME MEASURES: Survival beyond 2 months after optimal postnatal care. RESULTS: Fifty-eight percent (48 of 83) died despite optimal postnatal care (95% confidence interval, 41% to 75%). Of the 48 nonsurvivors, seven suffered intrauterine fetal demise, four were too premature for ECMO, 16 died before ECMO could be started, and 21 died despite ECMO therapy. Twenty-two of the 35 survivors received ECMO, and nine of these have severe chronic illness attributable to the intensive management. CONCLUSIONS: In this study, the mortality for potentially correctable CDH diagnosed before 24 weeks' gestation is 58%, despite optimal care presently available after birth. Infants who die in utero and soon after birth constitute a substantial hidden mortality.

Extracorporeal Membrane Oxygenation↗

The unborn surgical patient. A nursing frontier.

The fetus can now be considered a patient. Sophisticated imaging techniques and prenatal tests have allowed precise diagnosis of fetal abnormalities. Subsequent recommendations for treatment are evolving depending on diagnosis and progression of disease. For severely affected fetuses with life-threatening problems, fetal surgery is a proposed intervention. Knowledge of the diagnosis and potential treatment modalities are now a prerequisite for providing the necessary support and care of mothers of fetuses with an anomaly. The fetal treatment center provides a regionalized approach to providing specialized care to the mother carrying a fetus with an anomaly. The center provides both prenatal and postnatal diagnosis; treatment; and obstetric, neonatal, and pediatric surgical management for a wide variety of pediatric surgical disorders. The fetal treatment center model is a useful one offering knowledgeable, coordinated, efficient, and compassionate care to parents facing difficult decisions regarding their unborn child. Future interventions include less invasive procedures to the mother, such as videofetoscopic techniques. Use of new research related to scarless wound healing may allow endoscopic techniques to correct cleft lips in utero. Gene and stem cell therapy in utero may ameliorate blood disorders, enzyme deficiencies, hemoglobinopathies, and so on prior to birth. Finally, other lethal fetal anomalies, such as pulmonary atresia and laryngeal atresia may also benefit from in utero intervention.

Female↗

Fetal surgery for cystic adenomatoid malformation of the lung.

We reviewed our experience with fetal therapy for congenital cystic adenomatoid malformation of the lung (CCAM) at the University of California, San Francisco Fetal Treatment Center. Fetuses with life-threatening CCAM were selected for prenatal treatment according to predetermined guidelines, including the gestational age of the fetus, the size of the intrathoracic lesion, maternal health, and the development of fetal hydrops. The knowledge that fetuses with hydrops are at high risk for fetal or neonatal death led to fetal surgical resection of the massively enlarged pulmonary lobe (fetal lobectomy) in six cases. In the first case, resection was too late, since preoperative labor and maternal preeclampsia could not be reversed, leading to premature delivery of a nonviable infant. In the next four cases, CCAM resection led to resolution of the hydrops, impressive in utero lung growth, and neonatal survival. Right middle and lower lobe resection in the sixth fetus at 21 weeks was successful, but subsequent inexplicable fetal death highlights the need for better postoperative fetal monitoring and treatment. Three other fetuses with a single predominant cyst underwent thoracoamniotic shunt placement alone; two survived after delivery and prompt neonatal surgery with the assistance of high-frequency ventilation or extracorporeal membrane oxygenation. Fetal therapy can now be considered for otherwise fatal space-occupying intrathoracic lesions in the fetus.

Adult↗

The Fetal Treatment Center.

Unanimity of opinion about clinical decisions will always be difficult among a variety of specialists with disparate backgrounds. The Fetal Treatment Center is a regionalized approach that utilizes the necessary specialists and facilities to provide the most accurate diagnosis and maternal-fetal patient care management recommendations to referring physicians. This model offers a systematic approach for the mother carrying a fetus with an anatomic anomaly.

Congenital Abnormalities↗

Tracheostomy in children with emphasis on home care.

Tracheostomy in children is not a benign procedure. Tracheostomy-related mortality rates among children have been previously reported to be as high as 10% to 27%. Children with tracheostomies are especially vulnerable after home discharge with mortality rates of 0.5 to 2 deaths per 100 months at home. In order to assess the impact of extensive parental education and home nursing care on tracheostomy-related mortality, we report our experience over 9 years with 44 children receiving tracheostomies. Each child was maintained at home with a tracheostomy for an average of 19 months for a total of 635 months of home tracheostomy care. Indications for tracheostomy were tracheomalacia (32%), obstructive airway lesions (23%), central nervous system lesions (16%), vocal cord paralysis (9%), Pierre Robin syndrome (9%), and a list of miscellaneous conditions (11%). Our tracheostomy care regimen begins with intensive parental training in tracheostomy management for a minimum of 10 days prior to discharge. Home nursing was arranged for 77% of these children for an average of 11 hours per day at the time of discharge. Eighty-three percent had home apnea monitors. Discharge of these children was delayed or transfer to a secondary hospital was made when parents failed to show adequate proficiency in tracheostomy management with existing home nursing. Eight percent were ventilator dependent at discharge. As of January 1, 1989, 34% of these children have been decannulated. There were six deaths, all due to underlying disease. There were no tracheostomy-related deaths in hospital or after discharge home.(ABSTRACT TRUNCATED AT 250 WORDS)

Child, Preschool↗

Tracheobronchial obstructions in infants and children. Experience with 45 cases.

Forty-five infants and children with intrathoracic tracheobronchial obstructions requiring surgical treatment are reported. Segmental stenosis of the trachea is defined as involvement of less than one half the length of the airway, which affected six infants. Elongated stenosis involving more than one half the length of the trachea was seen in 12 infants, and complete annular cartilage rings, along the entire length of the trachea, were present in 11. Severe tracheomalacia occurred in six infants associated with aortic arch anomalies and in nine infants with esophageal atresia. Segmental tracheal resection was performed in 17 cases (two after failure of a rib cartilage graft), and anastomotic stricture developed in three. These three anastomotic strictures were resected, resulting in an excellent airway in two and restricture in one. Rib cartilage grafts were used in five patients: two of three with elongated stenosis with complete tracheal rings required subsequent resection, and one of two infants with tracheomalacia had excellent outcome. Approximately 50% of an infant's trachea can be resected, but rib cartilage grafts should be used for elongated stenosis. Resection of bronchial stenosis in two patients resulted in a widely patent bronchus. From this experience primary segmental tracheobronchial resection and re-resection of recurrent stenosis are highly successful. Anastomotic stricture is due to tension at the suture line and suture material inciting a fibrotic reaction. Rib cartilage grafts amounting to 25% or less of the circumference of the airway readily resurfaces with adjacent epithelium, but when 30% or more of the circumference is rib graft, epithelialization may be impaired.

Bronchial Diseases↗