Single-port tracheoscopic surgery in the fetal lamb

[Fetoscopic tracheal occlusion for severe congenital diaphragmatic hernia: retrospective study]

BACKGROUND AND OBJECTIVES

The temporary fetal tracheal occlusion performed by fetoscopy accelerates lung development and reduces neonatal mortality. The aim of this paper is to present an anesthetic experience in pregnant women, whose fetuses have diaphragmatic hernia, undergoing fetoscopic tracheal occlusion (FETO).

METHOD

Retrospective, descriptive study, approved by the Institutional Ethics Committee. Data were obtained from medical and anesthetic records.

RESULTS

FETO was performed in 28 pregnant women. Demographic characteristics: age 29.8±6.5; weight 68.64±12.26; ASA I and II. Obstetric: IG 26.1±1.10 weeks (in FETO); 32.86±1.58 (reversal of occlusion); 34.96±2.78 (delivery). Delivery: cesarean section, vaginal delivery. Fetal data: Weight (g) in the occlusion and delivery times, respectively (1045.82±222.2 and 2294±553); RPC in FETO and reversal of occlusion: 0.7±0.15 and 1.32±0.34, respectively. Preoperative maternal anesthesia included ranitidine and metoclopramide, nifedipine (VO) and indomethacin (rectal). Preanesthetic medication with midazolam IV. Anesthetic techniques: combination of 0.5% hyperbaric bupivacaine (5-10mg) and sufentanil; continuous epidural predominantly with 0.5% bupivacaine associated with sufentanil, fentanyl, or morphine; general. In 8 cases, there was need to complement via catheter, with 5 submitted to PC and 3 to BC. Thirteen patients required intraoperative sedation; ephedrine was used in 15 patients. Fetal Anesthesia: fentanyl 10 to 20mg·kg^-1 and pancuronium 0,1-0,2mg·kg^-1 (IM). Neonatal survival rate was 60.7%.

CONCLUSION

FETO is a minimally invasive technique for severe congenital diaphragmatic hernia repair. Combined blockade associated with sedation and fetal anesthesia proved safe and effective for tracheal occlusion.

New and/or improved aspects of fetal surgery

Open fetal surgery through a wide hysterotomy is no longer a real option for prenatal intervention, but a minimally invasive approach has emerged as treatment for a small number of indications. Endoscopic ablation of placental vessels is the preferred treatment for severe twin-to-twin transfusion syndrome and it may be the only chance to salvage the most severe forms of congenital diaphragmatic hernia. Several other indications are currently under review and may become justified in the future, provided that diagnostic accuracy and patient selection become more accurate. Before invasive fetal intervention becomes widely accepted, however, we need to better define outcome. It is no longer acceptable to express results in terms of survival at birth. Survival at discharge and long-term morbidity must be considered as well.

The pediatric surgeons' contribution to in utero treatment of twin-to-twin transfusion syndrome

OBJECTIVE

To evaluate the outcome of twin-to-twin transfusion syndrome (TTTS) treated using a combination of endoscopic fetal surgery-specific techniques and surgical restraint.

SUMMARY BACKGROUND DATA

TTTS is a condition of identical twins that, if progressive and left untreated, leads to 100% mortality. The best treatment option is obliteration of the intertwin placental anastomoses, but fetal surgery carries significant maternal and fetal risks. Even if successful, percutaneous endoscopic laser ablation of placental vessels (LASER) causes premature rupture of membranes (PROM) in 10% to 20% of pregnancies. Patient selection is particularly critical because the progression of the disease is unpredictable. This has prompted many to intervene early, yielding survival rates of >=1 twin of 75% to 80%.

METHODS

We developed a minimally invasive approach to fetal surgery, a unique membrane sealing technique and a conservative algorithm that reserves intervention for severe TTTS. Pregnancies with TTTS (stages I-IV) managed in the last 8 years were reviewed. LASER was offered in stage III/IV only.

RESULTS

Ninety-eight cases of TTTS were managed in a pediatric surgery/maternal-fetal medicine collaborative Fetal Treatment Program-39 were observed (40%) and 59 underwent LASER (60%). Survival of >= twin was seen in 82.7%, and overall survival was 69.4%. These survival rates are similar to, or better than, other comparable series with similar stage distribution (low:high stage ratio 1:1) in which all patients underwent LASER. PROM rate was 4%.

CONCLUSIONS

Reserving LASER treatment for severe TTTS results in outcomes similar to, or better than, LASER for all stages. Applying fetal surgery-specific endoscopic techniques, including port-site sealing, reduces postoperative complications.

[Fetal surgery]

Fetal surgery is a newly evolving multidisciplinary medical field, being performed in specialized centers. It deals with the treatment of selected fetuses with congenital anomalies that cause high morbidity and mortality. The aim of the surgical treatment is to avoid the development of progressive and eventually irreversible damage at birth. Examples of entities treated are obstructive uropathy leading to renal insufficiency, lung hypoplasia in severe congenital diaphragmatic hernia, severe congenital cystic adenomatoid malformation of the lung, and sacrococcygeal teratoma. This review describes principles of fetal surgery, physiopathologic processes of some of the anomalies treated in this way, and diagnostic and therapeutic approaches. Recently published results are presented and discussed.

What--and why--the pediatric surgeon should know about twin-to-twin transfusion syndrome

Abstract Endoscopic laser ablation of placental vessels is the most commonly performed fetal operation today. Herein, we review the pathophysiology of twin-to-twin transfusion syndrome and the challenges of its treatment. Pediatric surgeons, with their knowledge of fetal and congenital pathology, and their technical expertise with minimally invasive surgery, can be of great benefit to the patient and the medical team.

Fetoscopic tracheal occlusion (FETO) for severe congenital diaphragmatic hernia: evolution of a technique and preliminary results

BACKGROUND

Congenital diaphragmatic hernia (CDH) with liver herniation and a lung area to head circumference ratio (LHR) < 1 [corrected] is associated with a high rate of neonatal death due to pulmonary hypoplasia.

METHODS

We report the development of a minimally invasive and reversible fetoscopic tracheal occlusion (FETO) with a balloon, carried out in 21 consecutive fetuses with severe CDH.

RESULTS

Endotracheal placement of the balloon was successfully performed in all 21 cases and the mean duration of the operation was 20 (range, 5-54) min. The median gestation at FETO was 26 (range, 25-33) weeks. There were no maternal complications such as hemorrhage, placental abruption or pulmonary edema. In 11 (52.4%) patients there was postoperative prelabor amniorrhexis, which occurred within 2 weeks in five patients and after 2 weeks in six patients. Ultrasound scans after FETO demonstrated an increase in the echogenicity of the lungs within 48 h and improvement in the LHR from a median 0.7 (range, 0.4-0.9) before FETO to 1.8 (range, 1.1-2.9) within 2 weeks following surgery. The median gestation at delivery was 34 (range, 27-38) weeks and in 17 (77.3%) patients delivery occurred after 32 weeks. Nine babies died in the neonatal period due to complications from pulmonary hypoplasia. Surgical repair of the diaphragmatic hernia was carried out in 12 babies and in all but one the defect was extensive and required the insertion of a patch. Ten of these babies survived, and at the time of writing were aged 6-25 (median, 18) months and were developing normally. Survival was 30% in the first group of 10 fetuses and 63.6% in the second group of 11 fetuses. The total number of cases was too small for definite conclusions to be drawn as to the causes of this apparent improvement in survival. Nevertheless, improved survival coincided with a shift in the timing of FETO from the third to the second trimester, the administration of epidural rather than general anesthesia, reduced incidence of postoperative amniorrhexis and a change in the policy on the timing of removal of the balloon from the intrapartum to the prenatal period. During the same period of study there were 17 cases examined in the participating centers that met the criteria for FETO but which declined prenatal therapy. In all cases there was isolated left-sided CDH with liver in the thorax and LHR of 0.4-0.9 (mean, 0.7). In five cases the parents elected to terminate the pregnancy. In the 12 cases with expectant management all babies were liveborn but 11 died in the neonatal period due to pulmonary hypoplasia and only one (8.3%) survived.

CONCLUSION

Severe CDH can be successfully treated with FETO, which is minimally invasive and may improve postnatal survival.

Minimal-access fetal surgery for twin-to-twin transfusion syndrome

BACKGROUND

Laser ablation of placental vessels effectively halts severe twin-to-twin transfusion syndrome (TTTS), but fetal surgery remains a dangerous approach. The authors present the technical aspects of endoscopic fetal surgery in their initial clinical experience.

METHODS

Altogether, 11 women underwent endoscopic fetal surgery for severe TTTS. Access to the recipient's sac was obtained by the Seldinger technique via minilaparotomy. A 12-Fr peel-away introducer was used as a cannula to accommodate a custom-curved 9-Fr sheath containing a 1.9-mm semirigid fiber endoscope. Laser ablation was performed on all unpaired vessels crossing the intertwin membrane using a 400- micro m neodymium: yttrium-aluminum-garnet (Nd: YAG) fiber. The cannula was removed over a gelatin sponge plug.

RESULTS

The median operating time was 65 min (range, 45-105 min). No patient experienced amniotic leak postoperatively. The length of hospital stay was 2.8 +/- 1.6 days. Immediate improvement of the TTTS was noted in all but two patients. Pneumonia developed, in one mother leading to premature labor. There were no other major surgical complications. Fetal survival at 2 weeks was 73%.

CONCLUSIONS

The safety and efficacy of endoscopic fetal surgery for severe TTTS can be optimized with the application of current minimal-access techniques. The superiority of this approach over less invasive means is still being evaluated through prospective studies.

Fetal surgery for lung lesions, congenital diaphragmatic hernia, and sacrococcygeal teratoma

After more than 2 decades of experimental and clinical work, fetal surgery is an accepted treatment option for highly selected fetuses with life-threatening anomalies. Fetal lung masses associated with hydrops are nearly 100% fatal. These lesions can be resected in utero if they are predominantly solid or multicystic. Thoracoamniotic shunt placement may be effective in the setting of a single large cyst. Fetuses diagnosed with left congenital diaphragmatic hernia before 26 weeks' gestation with associated liver herniation and a low right lung to head circumference ratio have a relatively poor prognosis with conventional therapy after birth, but in utero therapeutic approaches have yet to show a comparative survival benefit. A prospective randomized trial is required to critically evaluate the efficacy of fetal tracheal occlusion for severe diaphragmatic hernia. Fetal sacrococcygeal teratoma complicated with progressive high output cardiac failure may benefit from in utero resection of the tumor.

Minimal access fetal surgery

The development of fetal surgery has led to promising therapeutic options for a number of congenital malformations. However, preterm labor (PTL) and premature rupture of membranes continue to be ubiquitous risks for both mother and fetus. To reduce maternal morbidity and the risk of prematurity, minimal access surgical techniques were developed and are increasingly employed. Congenital diaphragmatic hernia (CDH), obstructive uropathy, twin-to-twin transfusion syndrome (TTTS), and sacrococcygeal teratoma have already been successfully treated using minimal access fetal surgical procedures. Other life-threatening diseases as well as severely disabling but not life-threatening conditions are potentially amenable to treatment. The wider application of minimal access fetal surgery depends on a continued improvement in technology and a better understanding of complications associated with fetal intervention.

Fetoscopic temporary tracheal occlusion by means of detachable balloon for congenital diaphragmatic hernia

Occlusion of the fetal trachea blocks the egress of fetal lung fluid and stimulates the growth of hypoplastic lungs in fetuses with diaphragmatic hernia. Accomplishing temporary and reversible occlusion of the fetal trachea has proven difficult without invasive fetal surgery. Using simultaneous real-time ultrasonography and fetal bronchoscopy through a single uterine port, we placed a detachable balloon in the trachea of 2 fetuses with severe diaphragmatic hernia. In both fetuses the fetal lung subsequently enlarged, allowing survival after birth.

Balloon tracheal occlusion for congenital diaphragmatic hernia: experimental studies

PURPOSE

Temporary tracheal occlusion is an effective strategy to enlarge fetal lungs, but the optimal technique to accomplish occlusion is unknown. External clips are effective when applied fetoscopically (Fetendo clip), but require a difficult fetal neck dissection. This study was undertaken to assess the feasibility of intratracheal balloon occlusion, revisiting the internal occlusion strategy.

METHODS

(1) The internal diameter (ID) of human fetal trachea (53 fetuses; 14 to 41 weeks' gestation) was compared using a computer-assisted image analyzer and sonography, ex vivo. (2) Volume to diameter relationship of the balloon (balloon configuration curve) was defined using an image analyzing computer. (3) Using the trachea of fetal sheep, pressures that break balloon tracheal seal (seal pressure) were investigated.

RESULTS

(1) Between 16 and 41 weeks' gestation, tracheal ID (range, 0.7 to 5.4 mm) correlates significantly with gestational age. (2) Balloon volume required to achieve tracheal seal could be determined based on the tracheal growth curve and the balloon configuration curve. (3) Tracheal seal breaking points varied depending on the tracheal specimen tested.

CONCLUSION

Internal tracheal occlusion using a balloon is feasible with minimal tracheal damage if the balloon volume is adjusted to fetal tracheal growth.

Requirements for fetal surgery: the diaphragmatic hernia model

Fetal surgery for congenital diaphragmatic hernia and other fetal conditions can only be considered if (1) the morbidity of antenatal intervention is acceptable, (2) the diagnosis of the condition can be made accurately, (3) the condition can be differentiated from other, non-surgical anomalies. In addition, (4) the natural evolution of the disease, if left untreated, should be predictable, and the condition should be lethal or severely debilitating, (5) there should not exist adequate postnatal treatment, and (6) the proposed in utero operation should be technically feasible. Open fetal surgery has proven too invasive to be justified for the treatment of diaphragmatic hernia, and progress in postnatal therapy (including ECMO) has dramatically improved the neonatal outcome in all but a severe subgroup of patients. Recently, advances in endoscopic fetal surgery (which appears to be less stressful for the fetus and the gravid uterus) and a new approach to accelerate fetal lung growth and maturation have renewed the feasibility of in utero intervention for diaphragmatic hernia.

Tracheal side effects of endoscopic balloon tracheal occlusion in the fetal lamb model

OBJECTIVE

To evaluate effects of in-utero endoluminal balloon tracheal occlusion (TO) as suggested for the treatment of Congenital Diaphragmatic Hernia (CDH) on the higher airways of a fetal lamb model.

STUDY DESIGN

Fetuses from time-dated pregnant ewes underwent at 94 days (term=145 days) in-utero tracheal occlusion. In study animals an endoluminal, detachable balloon was placed by tracheoscopy. For that purpose a 1.2mm fibre-optic, semi-rigid endoscope and a medically graded latex balloon were used. In group I (n=9) lambs were delivered after 2 weeks. In group II (n=8) the tracheal occlusion was released after 2 weeks, to allow in-utero recovery until term. In positive control animals (group III; n=5) the trachea was clipped at 98 days and fetuses were harvested near term by cesarean section. A total of 17 contralateral littermates in multiple pregnancies served as negative controls. After macroscopic inspection of the trachea, sections were evaluated by light microscopy. Alterations were scored with an empirical interval score for each of the different anatomical elements in the fetal trachea (epithelium, submucosa, cartilage, pars membranacea).

RESULTS

For the animal experiments in group I, all balloons were found in place and according to the pulmonary response they were obstructive. Tracheas were macroscopically dilated by the plug mainly due to elongation of the pars membranacea. The total histologic score was correlated to the increase in circumference (mean increase: 3.0mm). In nearly all cases, the tracheal epithelium at the level of the plug had lost its typical folding pattern. In 44% of cases, local epithelial defects were observed and in 33% of cases there was squamous metaplasia. A chronic inflammatory response was present in over half of the cases, sometimes with giant cell reaction. In group II (the in-utero recovery group) the total score was significantly lower than in group I, with much less prominent unfolding and absence of epithelial defects. Squamous metaplastia was still present in half of the cases; whereas inflammatory responses were less frequent. In group III the trachea expanded normally after removal of the clip. The epithelium had compacted folds, and cilia were well preserved. In two animals however, intraluminal synechia were observed. Below the level of occlusion animals of groups I and II all showed areas of unfolding, but without metaplasia or epithelial defects.

CONCLUSION

Tracheal obstruction by means of endoluminal plugging has been suggested as an alternative in-utero treatment for congenital diagphragmatic hernia. The balloon causes mild epithelial changes, such as unfolding, limited epithelial defects (<25% of the exposure surface) and local inflammatory changes. These changes disappear nearly completely following in-utero unplugging during the rest of gestation. Unfolding of the epithelium is also seen in the trachea under the plug.

Open fetal surgery for life-threatening fetal malformations

After more than two decades of experimental and clinical work, fetal surgery has become an accepted treatment modality for selected fetuses with life-threatening anomalies. Color Doppler ultrasound and ultrafast fetal magnetic resonance imaging have enhanced the accuracy of prenatal evaluation traditionally made by ultrasound alone. Fetal lung masses associated with hydrops are nearly 100% fatal. These lesions can be resected in utero if they are predominantly solid or multicystic. Thoracoamniotic shunting may be effective in the setting of a single large predominant cyst. Fetuses diagnosed with left congenital diaphragmatic hernia before 26 weeks' gestation with liver herniation and a sonographic right lung to head circumference ratio (LHR) of less than one may benefit from fetal tracheal occlusion. Fetal sacrococcygeal teratoma complicated with placentomegaly, hydrops, or progressive high output heart failure may benefit from in utero resection of the tumor. Although preterm labor still remains the Achilles heel of open fetal surgery, effective tocolysis may, in the future, expand the scope of fetal surgery.

New developments in fetal lung surgery

After more than two decades of experimental and clinical work, fetal surgery has become a reasonable treatment modality for selected fetuses with life-threatening anomalies. We review the literature on anatomic anomalies of the fetal lung that are amenable to fetal surgical therapy. Ultrafast fetal magnetic resonance imaging has enhanced the accuracy of prenatal evaluation. Fetal lung masses associated with hydrops are nearly 100% fatal. These lesions can be resected in utero if they are predominantly solid or multicystic. Thoracoamniotic shunting may be effective in the setting of a single large predominant cyst. Fetuses diagnosed with left congenital diaphragmatic hernia before 26 weeks' gestation, who have liver herniation and a sonographic right lung-to-head circumference ratio of less than 1.0, may benefit from temporary fetal tracheal occlusion to enhance lung growth before birth.

Temporary tracheal occlusion causes catch-up lung maturation in a fetal model of diaphragmatic hernia

BACKGROUND

The lungs of infants born with diaphragmatic hernia are hypoplastic, immature, and surfactant-deficient. Tracheal occlusion in utero, which is being proposed as antenatal treatment of diaphragmatic hernia by promoting compensatory lung growth, decreases surfactant production as well, through loss of type II pneumocytes. The authors studied whether temporary tracheal occlusion might cause 'catch-up' lung growth and maturation, without negative effects of prolonged tracheal occlusion on the surfactant system.

METHODS

Diaphragmatic hernia was created in time-dated fetal lambs (65 to 75 days). At 108 days, the trachea was occluded with an embolectomy catheter (DH + TO, n = 6). After day 14, the balloon was deflated. Six congenital diaphragmatic hernia (CDH) fetuses were left unobstructed (DH). For comparison, a group of fetuses without diaphragmatic hernia were subjected to prolonged tracheal ligation (TL; 4-week tracheal ligation, n = 3). Unoperated littermates (n = 8) were used as controls (CTR). All were killed near term. Lung tissue was processed for light and electron microscopy (computerized stereologic morphometry). Type II pneumocytes were identified with antisurfactant protein B antibody.

RESULTS

Four animals in DH + TO and four in DH survived to term. Lung fluid volume (LFV) at 108 days was 5.2 +/- 4.4 mL in DH and 24.6 +/- 6.8 mL in controls (P < .05, Student t test). In DH + TO, LFV increased ninefold (to 48.3 +/- 13.3 mL) by 1 week postocclusion, suggesting accelerated lung growth. At term, lung weight to body weight ratio (LW/BW) was higher in TL (9.85% +/- 1.81%) than in CTR (3.55% +/- 0.56%; P < .05, analysis of variance); LW/BW and parenchymal volume tended to be greater in DH + TO than in DH, and air-exchanging parenchymal volume in DH + TO was similar to CTR (v a 50% reduction in DH), indicating some degree of hyperplasia after temporary occlusion. Pneumocyte II numerical density was decreased more than 10-fold in TL (60 +/- 22 v 826 +/- 324 in CTR, P < .001; it was slightly lower in DH + TO than in CTR, but individual type II pneumocyte cell volume was greater in the latter, and they appeared more mature than in DH (increased granulation by light microscopy, fewer glycogen granules, and abundant lamellar bodies by electron microscopy). Surfactant was also seen in the air spaces in DH + TO and CTR; it was absent in unobstructed CDH and in TL.

CONCLUSIONS

Temporary tracheal occlusion in utero does not cause the dramatic decrease in type II pneumocytes seen after prolonged occlusion. Although only minimal increase in lung volume is seen in CDH, catch-up parenchymal growth and maturation occur, most notably in the surfactant-producing system.