Mandibular distraction osteogenesis in the management of airway obstruction in children: a systematic review protocol

Transcription

1 Mandibular distraction osteogenesis in the management of airway obstruction in children: a systematic review protocol Omar Breik BDSc (Hons), MBBS 1 David Tivey BSc (Hons), PhD 1 Kandiah Umapathysivam BSc(Hons), MSc, GradDip (Business Admin) PhD 1 Peter Anderson DSc, MD(Edin), PhD, FDS RCS (Ed), FRCS (Eng), FRCS (Plast.), FACS, FRACS 2 1. The Joanna Briggs Institute, School of Translational Health Science, Faculty of Health Sciences, The University of Adelaide 2. Consultant, Australian Craniofacial Unit, Women s and Children s Hospital, Adelaide Corresponding Author Omar Briek omar.breik@gmail.com Review question/objective What is the effectiveness of mandibular distraction osteogenesis on airway patency and long-term development in children born with upper airway obstruction secondary to micrognathia? More specifically: Does mandibular distraction result in improved short- and long-term outcomes compared with tracheostomy? What is the ideal daily rate of mandibular distraction, and does the ideal rate differ between age groups? Background The upper airway in neonates and children differs from the upper airway of a normal adult. These structural differences are most dramatic in the neonatal upper airway and become less significant as the child grows. The main differences include that the larynx is located higher in the infant than in the adult which causes the tongue to sit more superiorly and closer to the palate in infants; a stiff and relatively larger epiglottis than in adults, and a tongue that is larger in proportion to the size of the mouth than the adult tongue. Infants also have poorly developed cartilaginous integrity, allowing for more laxity throughout the airway. Despite these differences, infants tend to maintain their airway patency via a fine balance of pharyngeal and lingual muscular tone and position. During normal respiration, diaphragmatic contraction initiates inspiratory airflow and the pharyngeal airway narrows because of the suction forces. The pharyngeal airway patency is maintained by a complex mechanism of pharyngeal-dilating muscles that counter the suction forces preventing the airway from collapse during inspiration. This doi: /jbisrir Page 16

2 requires precise coordination of the central nervous system, diaphragm, pharyngeal muscles, tongue muscles and laryngeal muscles. Any disturbance in the integrity of this finely tuned system can cause obstructive apnea. Neonatal and childhood obstructive apnea is a potentially lethal condition. Apart from the neurological and respiratory causes of neonatal apnea, structural causes of upper airway obstruction are important to recognize, but difficult to treat. An important structural cause of neonatal upper airway obstruction is micrognathia. The anterior mandible provides the anterior insertion of the genioglossus muscle of the tongue, creating the anterior position of the tongue. Micrognathia can hence cause airway obstruction due to posterior tongue displacement (glossoptosis), and hence physical obstruction of the oropharynx and hypopharynx. This was first widely described by Pierre Robin in 1923 and He described a constellation of findings including micrognathia, glossoptosis and in some patients a U-shaped cleft palate. This constellation of findings is now commonly known as a Pierre Robin Sequence (PRS). It is estimated to affect approximately one in 8500 births; however, many more patients are born with clinically significant micrognathia that is not characterized as a Pierre Robin Sequence. The clinical findings of micrognathia, glossoptosis and U-shaped cleft can also occur in other clefting conditions of the craniofacial skeleton, such as Treacher Collins Syndrome, Nager Syndrome, and others. The micrognathia and obstructive apnea contribute to a wide range of clinical problems in these children. Prolonged obstructive apneic episodes lead to hypercarbia and hypoxia. These children also tend to have higher caloric consumption due to their repeated attempts to clear their upper airway. It is unknown what effect the chronic hypoxia, hypercarbia and increased caloric intake have on the developing brain. These infants also have significant feeding and swallowing problems, secondary to an inability to respire and eat at the same time; thus often these infants fail to thrive 2. An increased incidence of gastro-esophageal reflux has also been observed in these children. It is hypothesized that upper airway obstruction results in negative intra-thoracic pressure that can cause a suction-type effect on the gastric contents. 3 All of these complications are secondary to the upper airway obstruction; hence the priority is to treat the upper airway obstruction. It is yet to be determined if relieving the upper airway obstruction will also resolve these complications. The majority of patients born with micrognathia are asymptomatic and can be treated conservatively, with prone positioning and/or non-invasive techniques like the use of a nasopharyngeal airway and/or application of nasal continuous positive airway pressure. The success of using nasopharyngeal airways has varied in the literature, ranging from 48% 4 to 100%. 5 As the neonate/infant grows, they often demonstrate mandibular growth that leads to an improvement in upper airway control and a reduction in apnea. Large case series looking at children with non-syndromic PRS determined that less than 10% required surgical intervention. 6 For neonates with severe obstructive apnea, or those for whom conservative treatment failed, the airway compromise can be a surgical emergency. Several surgical treatments have been suggested. In 1946, Douglas described the use of tongue-lip adhesion for the treatment of upper airway obstruction associated with micrognathia. 7 Some advocate this technique as the first line surgical treatment for the majority of children who failed conservative treatment and report successful outcomes. 8, 9 Others have challenged this approach, and found that most children who undergo tongue-lip adhesion required secondary surgical treatment within four months of initial treatment 10. Tongue-lip adhesion was also associated with complications like wound dehiscence and feeding difficulties. doi: /jbisrir Page 17

3 The default surgical option for micrognathia patients for whom conservative treatment has failed, is a tracheostomy. 11 Tracheostomy is a technique that creates an airway within the trachea, below the level of an upper airway obstruction. A tracheostomy however, is associated with significant morbidity, cost and mortality. Children with PRS who require a tracheostomy often require it for several years before decannulation, often suffering developmental delay and significant negative psychosocial impact on the child and their family 11. The principles of distraction osteogenesis originate in the early 1900s 12, but only found practical applicability in the 1950s in the works of Gavriil Ilizarov, a Russian Orthopaedic Surgeon who developed a procedure to lengthen long bones based on the biology of bone and the ability of the surrounding soft tissues to regenerate under tension. 13 He initially used the technique to treat fracture non-union and leg length discrepancy. This technique involved the following principles: 1. The healthy bone segments are sectioned with a saw. 2. The leg is then fitted with an external ilizarov frame, which maintains adequate immobilization and allows for controlled displacement of the two bone segments. 3. After a latency period of approximately four days, screws attached to both segments are turned at 1millimetre per day, so that new bone forming in the growth zone is gradually pulled apart to increase the gap. 4. After the ideal bone length is achieved, the leg is immobilized in the same frame for approximately one month for every centimeter of lengthened bone, allowing the new bone to mineralize and reach adequate strength for weight bearing. Since the mid-1980s to early 1990s, this technique has been adapted in the oral and craniomaxillofacial skeleton in order to deal with various types of reconstructive dilemmas. 14,15 Mandibular distraction osteogenesis for infants with mandibular hypoplasia begun at the same time, and was initially used for unilateral mandibular lengthening by distraction for cases of hemifacial microsomia, 16 and bilateral cases of Treacher Collins Syndrome. 17 In the first cases using mandibular distraction for improving upper airway obstruction, it was used to facilitate removal of a tracheostomy. Since then, it is increasingly used for the management of neonates and infants with micrognathia or Pierre Robin Sequence 10. Initially, corticotomies were performed in the mandible bilaterally, and external distractors were applied for the distraction process. The standard Ilizarov recommendation for rate of distraction of 1mm/day was employed. As with all areas of clinical medicine, with the advances of new technology and further experience with new techniques, various modifications have been made to the treatment protocol. External distractors were replaced by internal distractors, and there is substantial evidence that scarring is reduced without increasing the rate of infection 10. Other modifications include the corticotomy/osteotomy design, the rate of distraction, various latency periods for consolidation, and use of biological adjuncts, such as bone morphogenic protein to enhance bone regeneration in the distracted segment. Lack of longitudinal comparison between these procedures limits the surgeon s ability to select the appropriate procedure. The most important variable is the rate of daily distraction. The recommendation of 1mm/day by Ilizarov is for long bones and may not apply in the craniofacial skeleton. The studies on mandibular distraction to this point have been using a variety of distraction rates. These vary from distraction at a rate of 1mm/day, up to 5mm/day. 18 It is important to determine if there is an ideal daily rate of distraction, and doi: /jbisrir Page 18

4 whether it differs in certain age groups, as this may directly affect length of hospital stay, rate of early reoperation and rate of complications. A systematic review performed in 2007 and published in 2008 evaluated the effectiveness of mandibular distraction osteogenesis for use in several clinical applications. 19 This review included studies found using the Pubmed library on the applications of unilateral and bilateral mandibular distraction in both children and adults. Long-term outcomes in children were not evaluated, and the reasons for failure of distraction were also not discussed. The review reported the range of distraction rates, but did not compare the rate of distraction with patient outcomes; nor were various age groups compared. The results of several retrospective and prospective case series have been published since the review by Ow and Cheung. 19 This review protocol will build on the work of Ow and Cheung 19, by extending the search across multiple databases to include the current best available evidence for the effectiveness of mandibular distraction in comparison with tracheostomy for treating upper airway obstruction in children. It also aims to determine the effects of mandibular distraction on the other complications of micrognathia including gastro-esophageal reflux, feeding and weight gain, and facial development. Finally, this review also aims to determine if the surgical outcomes are affected by rate of distraction. Distracting the mandible by 1mm/day or 2mm/day or more may impact upon the rate of complications, early reoperation, and length of hospital stay. It is important to determine if there is an ideal rate of distraction for children undergoing mandibular distraction osteogenesis and whether this rate varies between age groups. Keywords Mandibular distraction osteogenesis; micrognathia; obstructive apnea; Pierre Robin; Tracheostomy Inclusion criteria Types of participants This review will consider studies that include: 1. Male and female children with clinical evidence of Pierre Robin Sequence or mandibular hypoplasia from birth 2. Children with upper airway obstruction for whom conservative treatments have failed 3. Syndromic and non-syndromic children with micrognathia 4. Children who have undergone bilateral mandibular distraction for consideration of decannulation and removal of a tracheostomy This review will not consider studies that include: 1. Children who underwent unilateral mandibular distraction 2. Children with central apnea, or acquired conditions that lead to airway obstruction for example trauma, iatrogenic injury and tongue disorders 3. Children with known abnormalities beyond the tongue base: hypopharynx and lower airway. doi: /jbisrir Page 19

5 Types of intervention(s)/phenomena of interest This review will consider studies that evaluate mandibular distraction osteogenesis. Comparator: tracheostomy Types of outcomes This review will consider studies that include the following outcome measures: Primary outcomes: - Airway patency/reversal of apnea - Decannulation of tracheostomized patients - Feeding and weight gain - Gastro-oesophageal reflux Secondary outcomes: - Long-term outcomes facial development and future surgical intervention - Surgical outcomes Airway patency - The primary outcome for consideration will be reversal of obstructive apnea and the ability of the child to maintain airway patency. This will be measured in some studies with polysomnographic results, that provide objective evidence of improvement. Other studies that will be considered will report subjective airway improvement based on the child being able to maintain oxygen saturations without additional airway supports. In children who already have a tracheostomy in place, the ability to de-cannulate after distraction osteogenesis also demonstrates the child s ability to maintain airway patency without adjuncts. Feeding and weight gain - As discussed above, upper airway obstruction leads to a hypermetabolic state, which often manifests as a failure to thrive. Children with micrognathia also tend to have swallowing abnormalities because of abnormal pharyngeal and tongue movements, leading to increased risk of aspiration and inability to tolerate oral intake. This outcome can be reported in studies as subjective assessment of the infant s ability to tolerate oral intake without coughing or evidence of aspiration, or requirement for feeding aids such as nasogastric tubes or percutaneous gastrostomy. Some studies may report rate of weight gain or results of swallow studies pre- and post-operatively. Gastro-esophageal reflux - This outcome of interest can be reported as a reduction in the symptoms of GORD, or objective evidence of improvement in upper GI series or ph monitoring before and after surgery. Long-term outcomes - This outcome of interest will evaluate evidence of normal or abnormal facial growth, and the need for future surgical intervention. This includes future pharyngeal surgery/orthognathic surgery or other surgical interventions. Ideally this outcome will be measured by cephalometric measurements compared with normal subjects at skeletal maturity. If available, studies that include long-term dental development in children who have undergone mandibular distraction will also be included. doi: /jbisrir Page 20

6 Surgical outcomes This outcome will look at important factors related to the surgical procedures themselves, and the complications associated with them. The main outcomes of interest are the number of days in hospital, the rate of complications and the need for early re-operation. The main complications for which data will be collected are: scarring, infections, pre-mature osseous fusion, early-re-operation and damage to the developing dentition. Subgroup analysis will be performed where possible to compare surgical protocols, syndromic and non-syndromic children with micrognathia, male and female patients, and age at time of surgery with regards to number of days in hospital, re-operation rates, and rate of complications. Types of studies This review will consider both experimental and epidemiological study designs including randomised controlled trials, and in their absence, non-randomised controlled trials, quasi-experimental, before and after studies, prospective and retrospective cohort studies, and case control studies. The review will also consider descriptive epidemiological study designs, including case series and case reports for inclusion. Search strategy The search strategy aims to find both published and unpublished studies. A three-step search strategy will be utilised in this review. An initial limited search of MEDLINE and CINAHL will be undertaken followed by analysis of the text words contained in the title and abstract, and of the index terms used to describe the article. A second search using all identified keywords and index terms will then be undertaken across all included databases. Thirdly, the reference list of all identified reports and articles will be searched for additional studies. Studies published in English will be considered for inclusion in this review. Only studies published after 1990 will be considered for inclusion in this review, as this is the first reported case of the use of mandibular distraction osteogenesis in children with airway obstruction. The databases to be searched include: PubMed, Embase, Scopus, Web of Knowledge; Grey Literature will be searched through the following databases: Scirus, Mednar, Proquest Theses and Dissertations, and Grey Source, Index to Theses, Libraries Australia. An example of a search strategy that will be used when searching the PubMed database includes: Child[mh] OR Child*[tw] OR Neonate[mh] OR Neonat*[tw] OR Infant[mh] Infant*[tw] OR Pediatric[tw] OR Paediatric[tw] OR Newborn[mh] OR Newborn[tw] AND Pierre Robin[tw] OR Pierre Robin sequence[tw] OR Robin sequence[tw] OR Micrognathia[tw] OR retrognathia[tw] OR mandibular hypoplasia[tw] OR Goldenhar[tw] OR Treacher Collins[tw] OR Nager[tw] OR Stickler[tw] OR Craniofacial Abnormalit*[tw] OR mandibulofacial dysostosis[mh] OR mandibulofacial dysostosis[tw] OR Jaw Abnormalities[mh] OR Mandibular Diseases/congenital[mh] AND doi: /jbisrir Page 21

7 Mandibular distract*[tw] OR Mandibular lengthen*[tw] OR Bone lengthening[mh:noexp] OR Osteogenesis, Distraction[mh] OR distraction osteogenesis[tw] OR Tracheostom* [mh] OR Tracheostomy*[tw] OR Tracheotomy[tw] OR Craniofacial Abnormalities/surgery[mh] OR Airway Obstruction/surgery[mh] OR Airway obstruction[tw] OR mandible/surgery[mh] OR surgery[mh] OR mandible[tw] AND Apnea[mh] OR Apnea[tw] OR Apnoea[tw] OR Airway obstruct*[tw] OR Airway patency[tw] OR Gastroesophageal reflux[mh] OR Gastro-esophageal reflux[tw] OR Feed*[tw] OR Weight gain[tw] OR Weight[tw] OR Facial growth[tw] OR Facial develop*[tw] OR dentition[tw] OR failure to thrive[tw] OR outcome[tw] OR molars[tw] Assessment of methodological quality Papers selected for retrieval will be assessed by two independent reviewers for methodological validity prior to inclusion in the review using the standardized critical appraisal instruments from the Joanna Briggs Institute Meta Analysis of Statistics Assessment and Review Instrument (JBI-MAStARI) (Appendix V). Any disagreements that arise between the reviewers will be resolved through discussion, or with a third reviewer. Data collection Data will be extracted from papers included in the review using the standardised data extraction tool from JBI-MAStARI (Appendix VI). The data extracted will include specific details about the interventions, populations, study methods and outcomes of significance to the review question and specific objectives. The authors of the included studies will be contacted if important data, relevant to the review, is not included in the published papers. Data synthesis Quantitative data will, where possible be pooled in statistical meta-analysis using JBI-MAStARI. All results will be subject to double data entry. Effect sizes expressed as odds ratio (for categorical data) and weighted mean differences (for continuous data) and their 95% confidence intervals will be calculated for analysis. Heterogeneity will be assessed statistically using the standard Chi-square and also explored using subgroup analyses based on the different study designs included in this review. Subgroup analyses will be performed where possible to compare surgical protocols, syndromic and non-syndromic children with micrognathia, external and internal distraction, and age at time of surgery, with regards to number of days in hospital, early re-operation rates, and rate of complications. Where statistical pooling is not possible, the findings will be presented in narrative form including tables and figures to aid in data presentation where appropriate. Conflicts of interests none doi: /jbisrir Page 22

8 References 1. Robin P. Glossoptosis due to atresia and hypotrophy of the mandible. Am J Dis Child.1934; 48: Hong P, Bezuhly M, Mark Taylor S, Hart RD, Kearns DB, Corsten G. Tracheostomy versus mandibular distraction osteogenesis in Canadian children with Pierre Robin sequence: a comparative cost analysis. J Otolaryngol Head Neck Surg.2012; 37( 2): Dudkiewicz, Z., Sekula, E., Nielepiec-Jalosinska, A.. Gastroesophageal reflux in Pierre Robin sequence--early surgical treatment. Cleft Palate-Craniofacial Journal.2000; 37( 2): Meyer AC, Lidsky ME, Sampson DE, Lander TA, Liu M, Sidman JD. Airway interventions in children with Pierre Robin Sequence. Otolaryngol Head Neck Surg.2008; 138( 6): Wagener, S., Rayatt, S. S., Tatman, A. J., Gornall, P., Slator, R.. Management of infants with Pierre Robin sequence. Cleft Palate Craniofac J.2003; 40( 2): Dauria D, Marsh JL. Mandibular distraction osteogenesis for Pierre Robin sequence: what percentage of neonates need it?. J Craniofac Surg.2008; 19( 5): Douglas B. The treatment of micrognathia associated with obstruction by a plastic procedure. Plast Reconstr Surg.1946; 1( 3): Argamaso RV. Glossopexy for upper airway obstruction in Robin sequence. Cleft Palate Craniofac J.1992; 29: Kirschner R E, Low D W, Randall P. Surgical airway management in Pierre Robin sequence: is there a role for tongue-lip adhesion?. Cleft Palate Craniofac J.2003; 40: Denny AD. Distraction osteogenesis in Pierre Robin neonates with airway obstruction. Clin Plast Surg.2004; 31( 2): Tomaski, S. M., Zalzal, G. H., Saal, H. M.. Airway obstruction in the Pierre Robin sequence. Laryngoscope.1995; 105( 2): Codivilla A. On the means of lengthening, in the lower limbs, the muscles and tis- sues which are shortened through deformity. Am J Orthoped Surg.1905; 2: Ilizarov S. The Ilizarov method: history and scope. In: S. Robert Rozbruch SI, editor. Limb Lengthening and Reconstruction Surgery New York: CRC Press; p Karp NS, Thorne CH, McCarthy JG, Schreiber JS, Sissons HA. Bone lengthening in the craniofacial skeleton. Ann Plast Surg.1990; 24: McCarthy, J. G., Schreiber, J., Karp, N., Thorne, C. H., Grayson, B. H.. Lengthening the human mandible by gradual distraction. Plast Reconstr Surg.1992; 89( 1): 1-8; discussion McCarthy, J. G.. The role of distraction osteogenesis in the reconstruction of the mandible in unilateral craniofacial microsomia. Clin Plast Surg.1994; 21: Moore, M. H., Guzman-Stein, G., Proudman, T. W., Abbott, A. H., Netherway, D. J., David, D. J.. Mandibular lengthening by distraction for airway obstruction in Treacher-Collins syndrome. J Craniofac doi: /jbisrir Page 23

9 Surg.1994; 5( 1): Miloro, M.. Mandibular distraction osteogenesis for pediatric airway management. J Oral Maxillofac Surg.2010; 68( 7): Ow A T C, Cheung L K. Meta-analysis of mandibular distraction osteogenesis: clinical applications and functional outcomes. Plast Reconstr Surg..2008; 121( 3): 54e-69e. Insert page break doi: /jbisrir Page 24

10 Appendix I: Appraisal instruments MAStARI appraisal instrument this is a test message Insert page break doi: /jbisrir Page 25

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13 Appendix II: Data extraction instruments MAStARI data extraction instrument Insert page break doi: /jbisrir Page 28

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