Many algorithms combine DLB with PSG in their initial evaluation of patients who are unresponsive to positioning.5 , 6 Although the majority of our respondents ordered DLB, not all do. Those who were >10 years in practice or practice internationally tended not to order this modality, despite the fact that up to 28% of children have concomitant lower airway abnormality beyond the base of tongue.5 Careful evaluation of the lower airway with laryngoscopy is necessary when considering surgical interventions that only address the upper airway.16 However, experience and regional differences in availability can preclude use. This may explain the increased likelihood of surgeons who did not order DLB resorting to tracheostomy as their initial surgical modality.
Overnight PSG is considered by some to be the gold standard investigating and quantifying obstructive sleep apnea (OSA).2 The majority of respondents always or sometimes use PSG, with North American surgeons and those <10 years in practice have a higher chance of doing so. Although a number of studies have used PSG to show improvement in apnea, thresholds for intervention remain highly variable with a recent systematic review highlighting studies using an AHI of 6.4 to 52.6 as their respective indications for surgical airway intervention.2 In our cohort, most surgeons selected an AHI of 11–29 as their minimum for intervention, but more than a quarter of surgeons selected either <11 and ≥30 as their thresholds. The wide variability may be explained by the (1) lack of normative data among different neonatal age groups and (2) lack of guidance from comparative data on severities of OSA among RS and the interventions that improve OSA at various severities.2 , 17 Furthermore, the lack of PSG in all institutions limits is use and may explain why only half of surgeons always use PSG.
Previously, our group presented results of a retrospective analysis of over 60 infants with RS, comparing characteristics of patients who did not require surgical airway interventions with those who did.18 Multivariate and ROC analysis demonstrated 4 features on PSG that distinguished the surgical group from the nonsurgical group, which we coined the MIST criteria. These characteristics were (1) Maximum CO2 > 62 mm Hg; (2) AHI > 23; (3) O2 Saturation nadir < 79.4%; and (4) Total sleep time with < 90% O2 saturation of > 5.7%. Interestingly, Fahradyan et al.19 found higher levels of carbon dioxide (pCO2) through a heel stick capillary blood gas to better “predict” surgical intervention than PSG, using similar ROC analyses. Both studies suffer from similar methodological problems that inherently stem from identifying predictors for surgery ex post facto, as these “predictors” likely influenced the clinical decision to proceed with surgical intervention. Further study is underway.
The wide spectrum of practice patterns seen in our survey may also in part be due to comfort and experiences in training.20 , 21 In a survey of ACPA members, Collins et al.20 found those trained in certain surgical techniques in RS are likely to perform those techniques at their current institution. This would explain the use of tracheostomy among international respondents, the increased use of MDO by those 0–10 years out of practice, and the preference for mandibular body osteotomies in surgeons >10 years in practice. A study examining practice patterns in Boston found that regional hospitals vary widely in initial treatment modality independent of disease severity, with some resorting to tracheostomy over other methods.21 Interestingly, in the same ACPA study performed by Collins in 2010, 48% of respondents perform MDO, 28% perform TLA, and 17% perform tracheostomies as their most common or preferred method.20 In our study that included ACPA membership, we found that 74.2% of surgeons preferred MDO, 12.6% perform TLA, and 6.6% perform tracheostomies as their surgical intervention of choice, suggesting an interval increase of MDO usage as the primary surgical modality over the last 8 years.
Since its original description, variations in technical aspects of mandibular distraction and postoperative protocols have been successfully used. Osteotomy techniques are generally a matter of preference so long as they are able to minimize morbidity to the inferior alveolar nerve and tooth buds and adequately lengthen the mandible. The majority of surgeons performed an inverted L ramus osteotomy or a mandibular angle osteotomy. Inverted L osteotomies were more likely in younger surgeons 0–10 years out in practice and in surgeons that perform >5 MDO a year. Proponents of the inverted L cite the ability to make the vertical osteotomy away from the tooth roots and under direct visualization to avoid the inferior alveolar nerve.22 This may be a reflection of training, as younger surgeons graduating from high volume academic centers may be inclined to utilize newer techniques.
The majority of surgeons in our study utilized a 1–3 day latency phase, while a quarter of surgeons did not incorporate a latency phase. A landmark survey of 3,278 distraction cases by Mofid et al.23 found an increase in self-reported premature consolidation among surgeons using a latency phase, on average 4.9 days. There are some clinical reports of eliminating the latency phase all together. Surgeons who eliminate the latency phase may rationalize this choice by noting that the initial distraction protocols were devised for the lower extremity in older patients, who are less likely to consolidate the distraction gap within a short period of time. Furthermore, distraction devices have inherent “play” in them by resistance of soft tissue and turns left in the distraction arm before the osteotomy sites actually distracts.24 In clinical series, there was no difference in clinical outcome when the latency phase was eliminated.25 , 26 With regard to the activation phase, surgeons were split, with one half distracting 1.0 mm/d (in accordance to McCarthy’s original protocol), and the other half distracting 1.5–2.0 mm/d.27 Clinical study has demonstrated increasing distraction to 2.0 mm/d does not result in fibrous union or premature consolidation.25 Further clarification of the age at which surgeons are distracting the majority of their patients would help clarify discrepancies. Despite variations in protocols, most surgeons in our study had self-reported high rates of successfully relieving upper airway obstruction with mandibular distraction, similar to findings in previous studies.20
There are several limitations to our study. Our relatively low response rate likely reflects the small proportion of surgeons who routinely treat RS. A selection bias must be considered, as many of the treatment modalities and diagnostic tests likely reflect the practice patterns of those who are highly specialized in treating this heterogeneous condition. Further, our study was not designed to elucidate subtleties in management among each practitioner’s algorithm. This would be outside of the scope of a 5-minute survey. Further investigations may clarify the nuances, clinical characteristics, and syndromes that can affect overall management. “Catch-up” growth, which behooves consideration when considering intervention, is a well-debated phenomenon.15 , 28–32 Although current longitudinal studies have failed to clearly demonstrate its existence, it is clear syndromic mandibles are different in morphology and physiology when compared with the nonsydromic variants.28 , 33 , 34 Careful consideration to the pathogenic diagnosis is paramount in successful treatment. Ultimately, this survey was able to establish clear trends in the current workup and surgical management of this heterogenous sequence. However, the need for large scale multi-institutional trials establishing treatment guidelines is ever apparent.
The current study demonstrated that while the majority of respondents seem to have developed successful, institutional specific algorithms for the treatment of upper airway obstruction in infants with severe RS, specific differences are evident, particularly between North American versus international craniofacial surgeons, and between those who were 0–10 years versus greater than 10 years of practice. Nevertheless, broad trends have been documented, including the use of DLB and PSG by the majority of respondents. MDO was the most favored primary surgical intervention, a trend increasing among newer generations of craniofacial surgeons. Large multi-institutional prospective studies are likely necessary to further define the roles various treatment protocols and syndromic diagnoses may play in successfully treating these complex patients, and to develop objective data-driven indications for surgical airway management.
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