Magnetic resonance imaging of the upper airway

Effects of propofol anesthesia and nasal continuous positive airway pressure in humans

Mali Mathru, Oliver Esch, John Lang, Michael E. Herbert, Gregory Chaljub, Brian Goodacre, Eric VanSonnenberg

Research output: Contribution to journalArticle

129 Citations (Scopus)

Abstract

Background: Anesthetic agents inhibit the respiratory activity of upper airway muscles more than the diaphragm, creating a potential for narrowing or complete closure of the pharyngeal airway during anesthesia. Because the underlying mechanisms leading to airway obstruction in sleep apnea and during anesthesia are similar, it was hypothesized that anesthesia-induced pharyngeal narrowing could be counteracted by applying nasal continuous positive airway pressure (CPAP). Methods: Anesthesia was induced in ten healthy volunteers (aged 25-34 yr) by intravenous administration of propofol in 50-mg increments every 30-s to a maximum of 300 ms. Magnetic resonance images of the upper airway (slice thickness of 5 mm or less) were obtained in the awake state, during propofol anesthesia, and during administration of propofol plus 10 cm nasal CPAP. Results: Minimum anteroposterior diameter of the pharynx at the level of the soft palate decreased from 6.6 ± 2.2 mm (SD) in the awake state to 2.7 ± 1.5 mm(P < 0.05) during propofol anesthesia and increased to 8.43 ± 2.5 mm (P< 0.05) after nasal CPAP application. Anteroposterior diameter of the pharynx at the level of the dorsum of the tongue increased from 7.9 ± 3.5 min during propofol anesthesia to 12.9 ± 3.6 mm (P < 0.05) after nasal CPAP. Pharyngeal volume (from the tip of the epiglottis to the tip of the soft palate, assuming this space to be a truncated cone) significantly increased from 2,437 ± 1,008 mm 3 during propofol anesthesia to 5,847 ± 2,827 mm 3 (P < 0.05) after nasal CPAP application. Conclusions: In contrast to the traditional view that relaxation of the tongue causes airway obstruction, this study suggests that airway closure occurs at the level of the soft palate. Application of nasal CPAP can counteract an anesthesia-induced pharyngeal narrowing by functioning as a pneumatic splint. This is supported by the observed reduction in anteroposterior diameter at the level of the soft palate during propofol anesthesia and the subsequent increase in this measurement during nasal CPAP application.

Original languageEnglish (US)
Pages (from-to)273-279
Number of pages7
JournalAnesthesiology
Volume84
Issue number2
DOIs
StatePublished - Feb 1996

Fingerprint

Continuous Positive Airway Pressure
Propofol
Anesthesia
Magnetic Resonance Imaging
Soft Palate
Airway Obstruction
Pharynx
Tongue
Epiglottis
Splints
Sleep Apnea Syndromes
Diaphragm
Intravenous Administration
Anesthetics
Healthy Volunteers
Magnetic Resonance Spectroscopy
Muscles

Keywords

  • Airway: management
  • Anesthetics, intravenous: propofol
  • Measurement techniques: magnetic resonance imaging
  • Ventilation: nasal continuous positive airway pressure

ASJC Scopus subject areas

  • Anesthesiology and Pain Medicine

Cite this

Magnetic resonance imaging of the upper airway : Effects of propofol anesthesia and nasal continuous positive airway pressure in humans. / Mathru, Mali; Esch, Oliver; Lang, John; Herbert, Michael E.; Chaljub, Gregory; Goodacre, Brian; VanSonnenberg, Eric.

In: Anesthesiology, Vol. 84, No. 2, 02.1996, p. 273-279.

Research output: Contribution to journalArticle

Mathru, Mali ; Esch, Oliver ; Lang, John ; Herbert, Michael E. ; Chaljub, Gregory ; Goodacre, Brian ; VanSonnenberg, Eric. / Magnetic resonance imaging of the upper airway : Effects of propofol anesthesia and nasal continuous positive airway pressure in humans. In: Anesthesiology. 1996 ; Vol. 84, No. 2. pp. 273-279.
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