regarding cause of subcutaneous emphysema post transsphenoidal hypophysectomy

[frontier]

hi all,
      i just want to discuss one case .one lady 38 year old known case of hypothyroidism treated with tab thyroxine for one month underwent transsphenoidal hypophysectomy for pituitary adenoma was extubated in operation theatre and shifted to critical care unit with bradycardia,not responding with fixed and dilated pupil.INJ.ATROPINE .6 MG was given.she had cardiac arrest.CPCR started according to AHA guideline.when i tried to intubate failed twice with stylet ,there was laryngeal edema and larynx was anterior.i immediately secured the airway with size 3 LMA.saturation went upto 95%.patient had massive swelling of neck,chest and ventilation was difficult.percut tracheostomy tried failed.i put size 6 endotracheal tube with bougie.SPO2 65%.surgical tracheostomy was done.chest x ray done there was air in mediastinum.what was cause of subcutaneous emphysema?
                                                    thanks.regards.

[jafo1964]

The subcutaneous emphysema seems to be an extension of a pneumothorax that could have easily developed in this patient
1. Pneumothorax due to Volutrauma / Barotrauma to to aggressive IPPV. This could have lead to tension pneumothorax which itself is a well documented cause of bradyarrythmias and asystole.
2. Pneumothorax due to Cardiac compression due to rib fracture and pleural / pulmonary injury
3. In difficult airway instrumentation of airway with stilette and GEB can produce tracheal mucosal tear and hence could lead on to pneumothorax and massive mediastinal and subcutaneous airleak.
I have seen or encountered all the three causes of pneumothorax in my clinical practice

regs

[frontier]

sir,
  thanks for your reply.but sir there was no pneumothorax in chest x-ray post CPR.waiting for your input.
                  regards.

[jafo1964]

The only way for air to get in is if we put it there
Direct subcutaneous emphysema would have been a possibility if the fascial planes were breached by something like high pressure jet ventilation or gas insuffalation into tissue spaces like creating a pneumoperitoneum
In most other cases it usually occurs as an extension of air in the pleural space under pressure. The tracheal mucosal breach could just have facilitated this traversing of gas
With regards to a negative Xray finding, I wonder what position the Xray was taken in. Lying posture may have caused poor quality or artefactual problems. The pneumothorax needs to be more 150ml air to be picked up radiologically. Suppose there was a significant pneu,otorax and then through the tracheal mucosal injury it ran away into the mediastinum and then the lung expanded back, we could be missing the xray finding
This is only a hypothetical explanation and i am sure that what is confounding you could be correct
In anaesthesia it is prudent to think of common things first and always. So I am just applying these principles to your case

regs