Cervical computed tomography in patients with obstructive sleep apnea: influence of head elevation on the assessment of upper airway volume

J Bras Pneumol. 2016 Jan-Feb;42(1):55-60. doi: 10.1590/S1806-37562016000000092.
[Article in English, Portuguese]

Abstract

Objective: Obstructive sleep apnea syndrome (OSAS) has a high prevalence and carries significant cardiovascular risks. It is important to study new therapeutic approaches to this disease. Positional therapy might be beneficial in reducing the apnea-hypopnea index (AHI). Imaging methods have been employed in order to facilitate the evaluation of the airways of OSAS patients and can be used in order to determine the effectiveness of certain treatments. This study was aimed at determining the influence that upper airway volume, as measured by cervical CT, has in patients diagnosed with OSAS.

Methods: This was a quantitative, observational, cross-sectional study. We evaluated 10 patients who had been diagnosed with OSAS by polysomnography and on the basis of the clinical evaluation. All of the patients underwent conventional cervical CT in the supine position. Scans were obtained with the head of the patient in two positions (neutral and at a 44° upward inclination), and the upper airway volume was compared between the two.

Results: The mean age, BMI, and neck circumference were 48.9 ± 14.4 years, 30.5 ± 3.5 kg/m2, and 40.3 ± 3.4 cm, respectively. The mean AHI was 13.7 ± 10.6 events/h (range, 6.0-41.6 events/h). The OSAS was classified as mild, moderate, and severe in 70%, 20%, and 10% of the patients, respectively. The mean upper airway volume was 7.9 cm3 greater when the head was at a 44° upward inclination than when it was in the neutral position, and that difference (17.5 ± 11.0%) was statistically significant (p = 0.002).

Conclusions: Elevating the head appears to result in a significant increase in the caliber of the upper airways in OSAS patients.

Objetivo: : A síndrome de apneia obstrutiva do sono (SAOS) tem uma alta prevalência e riscos cardiovasculares significativos. É importante estudar novas abordagens terapêuticas para essa doença. A terapia posicional pode ser benéfica na redução do índice de apneia-hipopneia (IAH). Métodos de imagem têm sido utilizados para facilitar a avaliação das vias aéreas em pacientes com SAOS e podem ser utilizados para determinar a eficácia de determinados tratamentos. O objetivo desse estudo foi determinar a influência do volume das vias aéreas superiores, mensurado por TC cervical, em pacientes diagnosticados com SAOS.

Métodos: : Estudo observacional transversal com abordagem quantitativa. Dez pacientes com diagnóstico de SAOS por polissonografia e avaliação clínica foram submetidos a TC cervical convencional em posição supina com a cabeça em posição neutra e com inclinação de 44° para comparar os volumes das vias aéreas superiores.

Resultados: : As médias de idade, IMC e circunferência cervical foram de 48,9 ± 14,4 anos, 30,5 ± 3,5 kg/m2 e 40,3 ± 3,4 cm, respectivamente. A média de IAH foi de 13,7 ± 10,6 eventos/h (variação, 6,0-41,6 eventos/h). Quanto à gravidade da SAOS, 70%, 20% e 10% dos pacientes foram classificados como com SAOS leve, moderada e grave, respectivamente. O volume das vias aéreas superiores foi 7,9 cm3 maior com a inclinação de 44° da cabeça quando comparada à posição neutra, e essa diferença foi estatisticamente significativa (17,5 ± 11,0%; p = 0,002).

Conclusões: : A elevação cervical parece resultar em um aumento significativo do calibre das vias aéreas superiores em pacientes com SAOS.

Publication types

  • Observational Study

MeSH terms

  • Adult
  • Aged
  • Body Mass Index
  • Cervical Vertebrae / diagnostic imaging*
  • Cross-Sectional Studies
  • Female
  • Head*
  • Humans
  • Male
  • Middle Aged
  • Patient Positioning / methods*
  • Polysomnography
  • Reference Values
  • Respiratory System / diagnostic imaging*
  • Sleep Apnea, Obstructive / diagnostic imaging*
  • Statistics, Nonparametric
  • Tomography, X-Ray Computed / methods*