Single-Port Tracheoscopic Surgery in the Fetal Lamb

By Konstantinos Papadakis, Frarqois I. Luks, Jan A. Deprest, Veerie E. Evrard, HcW?ne Fiageole, Marc Miserez, and Toni E. Lerut

Providence, Rhode k/and and ieuven, Belgian

Be&ground/h-pose; Endoscopic fetal surgery could help avoid many of the problems associated with open fetal surgery, but the use of multiple ports may be too traumatic to the membranes. The authors describe a single-port tech- nique of tracheoscopic surgery in the fetus.

Methods: Time-dated pregnant ewes (95 to 105 days; term, 145 days) underwent midline laparotomy under general halothane anesthesia. A 5-mm-diameter balloon-tipped can- nula was introduced in the uterus by Seldinger technique. A I.2mm semirigid mini-endoscope, fitted inside a 9F, 20” curved sheath, was introduced under continuous, low- pressure irrigation, inside the fetus’ mouth, and advanced into the trachea.

Ffesu/ts; Endotracheal procedures, including temporary (n = II) and permanent balloon tracheal occlusion Cn = 30) and placement of a barbed guide wire for endotracheal occlusion device insertion (n = 12), were performed by intro-

ducing a l-mm diameter instrument alongside the telescope. These were successfully performed in 52 of the 53 fetuses. The rigidity of the telescope allowed controlled access to the pharynx; its curve allowed full tracheobronchial endoscopy with the fetus in utero.

Conchsions; The present technique marries the control and optical quality of a rigid endoscope with the physiological curve only a flexible instrument could offer until now. The types of procedures performed with this technique illustrate its potential as a research tool; the size (1.2-mm diameter), shape, and optical qualities of the telescope should make clinical applications possible. J Pediatr Surg 33:918-920. Copyright Q 1998 by W.B. Saun- ders Company.

INDEX WORDS: Fetal surgery, sheep, trachea, endoscopy, bronchoscopy.

0 PEN FETAL SURGERY has made many advances in the prenatal treatment of otherwise fatal condi-

tions. Unfortunately, the treatment modality itself carries a high fetal mortality and morbidity rate.l Endoscopic fetal surgery has, in recent years, been offered as a minimal access alternative to open surgery on the fetus.z-4 Several elaborate animal models have been described, such as the creation5 or correction of bilateral urinary tract obstruction6 or the treatment of amniotic band syndrome.7 However, clinical application appeared lim- ited to relatively simple surgical interventions at first, such as ligature of an acardiac, parasitic twin’s umbilical cord,8 or the laser coagulation of placental shunts to prevent the twin-to-twin transfusion syndrome.9x10 When tracheal occlusion to promote fetal lung growth was rediscoverednr3 and applied as an alternative treatment

From the Division of Pediatric Surgery~ Brown lJniversi& School of Medicine, Providence, RI and the Centre for Surgical Technologies, Katholieke Universiteit Leaven, Belgium.

Presented at the 29th Annual Meeting of the Canadian Association of Paediatric Surgeons, Bang Alberta, Canada, October 3-6, 1997.

Supported in part by Grant#5477from the Rhode Island Foundation. Address reprint requests to Francois I. Luks, MD, Division of

Pediatric Surgery, Hasbro Children 5 Hospital, 2, Dudley St, Suite 180, Providence, RI 02905.

Copyright 0 1998 by WB. Saunders Company 0022.3468/98/3306-0027$03.00/O

for congenital diaphragmatic hemia,14,r5 the field of endoscopic fetal surgery suddently expanded. To date, the placement of tracheal clips by intrauterine endoscopic techniques has been developed in an animal model16 and has even been described in humans.17

Although there is evidence that this new modality is less invasive for the fetus and less irritating to the uterns,18J9 clinical experience has shown that postopera- tive amniotic leakage and rnpture of the membranes poses a significant problem, particularly when multiple ports are used.g In this regard, fetal tracheobronchoscopy, described several years ago, z” offered the potential advan- tage of a direct access technique to obstruct the fetus’ upper airway to promote accelerated lung growth. Ini- tially, this approach still required relatively large diam- eter rigid or flexible telescopeszo and multiple endoscopic portszl Herein, we describe the application of endotra- cheal manipulation in the fetal lamb using a semirigid mini-endoscope through a single 5mm-diameter port, making future clinical application of fetal tracheoscopy more attainable.

MATERIALS AND METHODS

Mixed breed time-dated pregnant ewes (95 to 105 days’ gestation; term, 145 days) were used. Under general anesthesia (1% to 3% halothane in 100% oxygen), a midline laparotomy was performed and a gravid uterine horn exteriorized. After localizing the head of the fetus by

918 Journa/ ofPediatric .Sw-gerv,Vol33, No 6 (June), 1998: pp 918-920

SINGLE-PORT FETAL TRACHEOSCOPY 919

Fig 1. Semirigid fiberoptic mini-endoscope ~10,000 pixels par 1.2 mm diameter) with custom-bent sheath.

gentle palpation of the uterus, a single 5-mm balloon-tipped can&a (LaparoSAC. Malow Surgical Technologies: Willoughby. OH) was mserted by Seldinger techmque, as described elsewhere.zZ A I .2-mm diameter semirigid, fiberoptic mini-endoscope (miniscope, model 11505. Karl Storz Endoskope: Tuttlingen, Germany) was fitted inside a custom-curved (20’) 9F sheath (model 11501 KB; Karl Storz En- doskope; l%g 1). Under continuous low-pressure itrigatlon with normal saline, the endoscope was advanced through the cannula into the amniotic cavity, the fetal mouth, the pharynx, past the epiglottis and the vocal cords, and into the fetal trachea. Correct positioning of the telescope was confirmed by vlsuahzing tracheal rings, the separate ongin of the right upper bronchus, and the carina.

One of several procedures were performed, all through a l-mm instmment, catheter or needle. introduced in the sheath alongside the telescope (Fig 2). At the end of the procedure, the port was removed, and the uterus was closed with a single figure-of-eight polyglycolic acid suture through all uterine layers. All expenments were approved by the Institutional Animal Care and Use Committee of Brown University or the Ethics Comrmttee for Animal Experiments of the Kathoheke Umversiteit Leuven. and ammals were treated in accordance with guidelines of animal welfare.

RESULTS

There were no perioperative deaths. The procedure could be completed in 52 of the 53 fetuses. It had to be aborted in one because of a technical failure.

The unique characteristics of the mini-endoscope of- fered the advantages of both rigid and flexible telescopes.

Fig 2. Technique of single-port tracheoscopic procedures through a 5-mm-diameter balloon cannula.

The rigid sheath allowed controlled entry into the fetal mouth and pharynx without the need for external stabili- zation of the fetus* head. The gentle curve of the instrument. made possible by the semirigid properties of this novel endoscope, allowed easy passage into the upper airways without hyperextension of the fetal neck and guaranteed axial position of the telescope inside the trachea, rather than the scraping action of a straight telescope’s tip. Tracheoscopic procedures included inser- tion of a balloon catheter (4F pulmonary artery catheter) for aspiration of tracheal fluidZ3 (n = ll), insertion of a detachable balloon for tracheal occlusion (n = 30),zd retrieval of a tracheal occlusion device (n = 3). and insertion of a barbed guide wire (modified Kopans breast lesion localization needle, Cook OB/GYN; Spencer, IN) for placement of an expandable tracheal occlusion device (n = 12).z’

DISCUSSION

Whereas endoscopic fetal surgery (or “FETal ENDOs- copy”15) describes minimal access to the fetus’ surface, the present technique allows one to look inside the fetus. Fetal tracheoscopy makes it possible to produce endolu- minal occlusion to promote fetal lung growth,‘6J1 ~4.~~ to sample tracheal fluid in an experimental settingz3a27 or for tracheobronchial gene therapy.Z8 None of these modali- ties have been applied clinically, however, because of the relatively large size of the telescopes and the technical challenge of tracheal intubation in the human fetus. In addition, earlier experiments still required multiple inser- tion ports,‘6.21 increasing the risk of membrane rupture and amniotic leak, possibly leading to premature labor or chronic oligohydramnios.

The use of a miniaturized (1.2 mm) fiberoptic endo- scope with exceptional optical qualities (10,000 pixels) provides a more realistic diameter for clinical tracheos- copy. The use of this semi-rigid, curved telescope al- lowed us to safely and reproducibly perform various endoluminal procedures in the midgestational fetal lamb. Of course, the transition to human application may not be a simple one, given the anatomical and physiological differences between ovine and primate uterus and fe- tus.‘.1s.19 Unfortunately, the rhesus monkey’s small size would render the use of this intermediate model very challenging.

This technique combines the control and optical qual- ity of straight, rod-lens telescopes with the physiological curve only a flexible, fiberoptic telescope could offer until now. In addition, the telescope’s small diameter allows other devices to be introduced within the same sheath. Thus, tracheoscopic manipulations could be performed with a single “operative’. telescope, avoiding the need for

920 PAPADAKIS ET AL

additional ports. The various procedures described here obstruction until the mechanisms of accelerated fetal lung attest to the versatility of single-port tracheoscopic sur- growth are better understood.llJz.zg gery, whether as a research tool or, in the future, as a therapeutic modality. Although tempting, the availability ACKNOWLEDGMENTS of such a technique nevertheless should not be viewed as The authors express their gratitude to S. Storz-Rehling and G. Barki an indication for the widespread application of tracheal for their suppot? and technical assistance.

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