Source
Department of Anesthesiology, Teikyo University Chiba Medical Center, Ichihara, Japan.
Abstract
BACKGROUND:
Obstructive sleep apnea (OSA) is an independent risk factor for difficult and/or impossible mask ventilation during anesthesia induction. Postural change from supine to sitting improves nocturnal breathing in patients with OSA. The purpose of this study was to evaluate the effect of patient position on collapsibility of the pharyngeal airway in anesthetized and paralyzed patients with OSA. The authors tested the hypothesis that the passive pharynx is structurally less collapsible during sitting than during supine posture.
METHOD:
Total muscle paralysis was induced with general anesthesia in nine patients with OSA, eliminating neuromuscular factors contributing to pharyngeal patency. The cross-sectional area of the pharynx was measured endoscopically at different static airway pressures. Comparison of static pressure-area plots between the supine and sitting (62° head-up) allowed assessment of the postural differences of the mechanical properties of the pharynx.
RESULTS:
: Maximum cross-sectional area was greater during sitting than during supine posture at both retropalatal (median (10th-90th percentile): 1.91 (1.52-3.40) versus 1.25 (0.65-1.97) cm) and retroglossal (2.42 (1.72-3.84) versus 1.75 (0.47-2.35) cm) airways. Closing pressure of the passive pharynx was significantly lower during sitting than supine posture. Differences of the closing pressures between the postures are 5.89 (3.73-11.6) and 6.74 (4.16-9.87) cm H2O, at retropalatal and retroglossal airways, respectively, and did not differ between the pharyngeal segments.
CONCLUSIONS:
Postural change from supine to sitting significantly improves collapsibility of pharyngeal airway in anesthetized and paralyzed patients with OSA.
Anesthesiology. 2010 Oct;113(4):812-8
Related posts:
- Effects of Mandibular Posture on Obstructive Sleep Apnea Severity and the Temporomandibular Joint in Patients Fitted with an Oral Appliance
- Influence of tongue/mandible volume ratio on oropharyngeal airway in Japanese male patients with obstructive sleep apnea
- Sleep bruxism related to obstructive sleep apnea: the effect of continuous positive airway pressure.
- Comparative Effects of Two Oral Appliances on Upper Airway Structure in Obstructive Sleep Apnea
- Predictors of Response to a Nasal Expiratory Resistor Device and Its Potential Mechanisms of Action for Treatment of Obstructive Sleep Apnea
This is an interesting article. First we understand that trying to image the awake airway and draw a conclusion about possible success with an oral appliance is very compelling. Imaging takes a few forms CBCT or Pharyngometry it does not seem to matter. the key distinctions seem to be seated or supine as well as awake or asleep. This article seems to point to the changes in the patency of the airway in a seated position however I wonder how much of the change is in fact that the patient is awake and unconsciously defending the airway.
A picture of the airway will not indicate the tone of the tissue or the collapsibility of the airway. A few weeks ago SleepScholar posted an article on Spirometry flow volume curves as a possible predictor of airway patency. I wonder if the image and the spirometry would work together ot give a complete picture.
It seems there is always more to do.