Upper-airway Changes After Bimaxillary Advancement in OSAHS

One of the most effective surgical treatments for obstructive sleep apnoea / hypopnoea syndrome (SAHS) with global impact on the upper-airway (UA) is the maxilla-mandibular advancement (MMA). Retrospective-prospective observational study of: clinical outcomes, UA and dental-cranium-facial (DCF) morphology.

Population sample will be patients treated in the Maxillofacial Surgery department of "Hospital de Cruces". As inclusion criteria: ≥18 years-old, moderate-severe SAHS in supine position, multidisciplinary committee of sleep pathology evaluation for surgical indication, and written informed consents. As exclusion criteria: pregnant woman, SAHS of central origin, cranium-facial deformities that significantly modify normal UA, different surgery than MMA and inconclusive / incomplete tests. It is estimated ≥90% males; ≥90% 30-59 years-old; ≤10% extreme weights; 25% complementary surgeries; and sample size 40. Medical ethics code of the Declaration of Helsinki will be taken into account. To collect the pre- / postoperative data we will use, calibrated and standardized: polysomnography (PSG), computed tomography (CT), right face profile picture (RFP) and lateral teleradiography of the cranium (LTC). Furthermore, the Epworth scale and non-validated subjective self-perception test of facial aesthetics will be performed.

Clinical outcomes will be evaluated from PSG using apnoea / hypopnoea index and pulse oximeter oxygen saturation, and from Epworth scale. UA morphology from CT, globally and by specific locations, through lengths, volumes, areas, dimensions, and other measurements. DCF aspects from RFP and LTC, by Ricketts cephalometric basic analysis and facial aesthetics test. Statistical, descriptive analysis of frequencies and comparative by pairs of quantitative data will be by t-Student or Wilcoxon test, after checking the variables normality with the Kolmogorov-Smirnov test.

HYPOTHESIS:

H0: Upper-airway (UA) morphology does not change as a consequence of maxilla-mandibular advancement (MMA) in patients with moderate-severe obstructive sleep apnoea / hypopnoea syndrome (SAHS).

H1: UA changes as a consequence of MMA in patients with moderate-severe SAHS. To answer this hypothesis, the following will be determined: Vertical UA length, volume, axial areas, ellipticity, uniformity, prevertebral soft tissue (PST) and soft palate (SP) lengths and position of the hyoid bone.

As secondary hypotheses:

H0: Clinical outcomes of MMA in moderate-severe SAHS are not successful. H1: Clinical outcomes of MMA in moderate-severe SAHS are successful. To answer, the apnoea / hypopnoea index (AHI), pulse oximeter oxygen saturation (SPO2) and daytime sleepiness will be determined.

H0: DCF morphology is unfavourable as a result of MMA in moderate-severe SAHS. H1: DCF morphology is not unfavourable as a result of MMA in moderate-severe SAHS.

To answer, the parameters of the Ricketts cephalometric basic analysis will be quantified and interpreted, and the patient's self-perception will be assessed.

OBJECTIVES:

Specify and quantify morphological changes in key anatomical locations of the UA by computed tomography (CT), in terms of vertical lengths, volumes, areas, axial dimensions, and other measurements. These changes happen after MMA surgery in patients diagnosed with moderate-severe SAHS from a representative cohort. We are intended to demonstrate: shortening, increase in volume and areas, more elliptical and uniform shape, modifications of PST and SP and more anterior-superior hyoid bone position.

As secondary objectives, inherent to the treatment received, it is first intended to determine and evaluate clinical outcomes: objectively by polysomnography, and subjectively by the Epworth scale. Secondary, it is intended to specify and quantify changes in DCF morphology: objectively by a two-dimensional cephalometric analysis from lateral teleradiography of the cranium (LTC) and right face profile picture (RFP), and subjectively by a non-validated facial aesthetics test (FAT).

DESIGN:

Observational retrospective-prospective study, which does not make any modification of the usual clinical practice (surgical indication criteria, procedures, examinations, surgical techniques...), of: clinical outcomes, UA morphology, and DCF aspects of SAHS patients undergoing MMA.

* Logistic and organizational process for the participants: Explanations, invitation to participate, resolution of doubts, delivery of written information sheet and informed consent, collection of them and FAT. Everything will be done in two face-to-face clinic consultations that are already part of the usual work protocol of the Maxillofacial Surgery department of our hospital for patients with SAHS. It is estimated that it only involves about 10-15 minutes per consultation of extra time, without the need of additional specific appointments for the present study. With regard to clinical history, complementary examinations and surgical procedure, nothing additional is required regarding the usual workflow for SAHS patients in our department.
* Logistic and organizational process for researchers: It is based on office and digital work, without biological samples.

A sample size of 40 subjects is estimated, compiling previous studies and the Granmo® calculator. This would achieve significant statistics in all the parameters considered to answer the main hypothesis, and most of the secondary ones.

The Declaration of Helsinki code of medical ethics for research in human beings will be taken into account, protecting the health of the participant, being voluntary the inclusion, interrupting the investigation if it can be detrimental to the well-being of the participant and agreement of confidentiality in the IC. The "CEIC OSI Exkerraldea-Enkarterri-Cruces" committee has approved the study (Code CEIC E19/39).

DATA ANALYSIS:

We will analyze the qualitative and continuous quantitative variables in categorical variables. Descriptive statistics of frequencies will be calculated. For statistical inference, only comparisons are made between two continuous variables, all dependent and paired (pre- / post-). To verify that the variables follow a normal distribution, the Kolmogorov-Smirnov statistic will be used. The comparisons will then be made with the t-Student test for two dependent samples or the Wilcoxon ranks test if they do not follow a normal distribution. Statistically significant results will be considered if p ˂0.05.

Eligibility Criteria:
Inclusion Criteria:

* ≥18 years-old.
* Diagnosis by polysomnography of moderate-severe obstructive sleep apnoea / hypopnoea syndrome (SAHS) in supine position.
* Approval of the surgical indication by the multidisciplinary sleep committee of our hospital
* Written informed consent (IC) of photography or image recording, orthognathic surgery program inclusion and facial deformity surgery.
* Specific IC for inclusion in the present study.

Exclusion Criteria:

* Pregnant woman
* Central SAHS
* Medical-surgical history that significantly alter the normal upper-airway anatomy: trauma, tumour, major congenital craniofacial deformity
* Different orthognathic surgery than MMA
* Inconclusive / incomplete tests and data.