Mediastinal Masses, Anesthetic Interventions, and Airway Compression in Adults: A Prospective Observational Study
Summary by Keith Andrews DO, 03.10.22
Take Home Point:
- Life-threatening central airway collapse and/or cardiovascular collapse are well-known risks associated with general anesthesia in patients with large mediastinal masses
The mechanisms of cardiovascular instability in this setting have been experimentally identified, while those of central airway obstruction remain ill-defined and largely uninvestigated.
In this article, the authors observed no worsening of central airway compression in adults with large mediastinal masses when induction, positive pressure ventilation, and paralysis were introduced in a staged manner.
This suggests a need to reexamine presumed mechanisms of airway collapse during anesthesia in such patients.
From Miller: Anesthetic deaths occur mainly in children because of the more compressible cartilaginous airway and difficulty in obtaining a history of positional symptoms.
Full Summary :
This was a prospective observational trial of 17 adult patients with mediastinal compression classified as greater than 50% reduction in airway diameter all the way up to near total occlusion of an airway segment
Tested the long held belief that positive pressure ventilation and paralysis will cause collapse of the airway since negative inspiratory force and muscle tone should in theory prevent manual compression
After topicalization, patients were intubated awake and a bronchoscope was advanced to visualize the point of maximal stenosis in each patient. Then under direct visualization with measurement of the airway diameter at each stage, a the following process occurred:
1. spontaneous, awake ventilation
2. spontaneous, unconscious ventilation with sevo
3. positive pressure ventilation
4. PPV with paralysis
Researchers found that the airway diameter did not decrease with the introduction of PPV nor muscle paralysis, but it actually increased with initiation of PPV and again with initiation of paralysis.
None of the patients required life saving rigid bronch nor VV ECMO And all tolerated the process without desaturation
Since there appears to be worse airway collapse in a spontaneously breathing patient, rather than discontinuing PPV if desaturation occurs, the authors propose maintenance of PPV with advancement of an ETT or rigid bronch past the stenotic portion as an alternative treatment algorithm
Key Limitations:
Only for adults, the mechanics of children where MANY more fatalities have occurred should not be considered as part of this trial
Very short period of PPV and paralysis: the authors hypothesize that prolonged periods in this state may lead to progressive air trapping which can tip the transpulmonary pressure scale in a bad way that may promote airway collapse.
Additional Reading: