Case 22: Mediastinoscopy

Question 1

What are some contraindications to mediastinoscopy surgery?

Answer 1

Previous mediastinoscopy - strong contraindication

Relative contraindications

• Severe tracheal deviation
• Cerebrovascular disease
• Severe C spine disease with limited neck extension
• Previous chest radiation treatment
• Thoracic aortic aneurysm

Question 2

What is Lambert Eaton syndrome? How does it compare to Myasthenia gravis?

Answer 2

• Syndrome in which the formation of antibodies to prejunctional voltage gated calcium channels results in reduced release of acetylcholine at motor end plate.
• Patients presents with proximal muscle weakness of lower extremities and signs of autonomic dysfunction such as dry mouth, impotence, constipation, orthostatic hypotension.
• Lambert eaton improves with exercise where as Myasthenia gravis does not

Question 3

What is the difference between SIADH and Diabetes insipidus?

Answer 3

• Oversecretion of ADH can result in the syndrome of inappropriate ADH (SIADH) while under-secretion of ADH results in diabetes insipidus (DI). Diabetes insipidus can also result from kidneys that do not respond to ADH (nephrogenic DI); however, this is relatively rare.

Question 4

How do you perform needle cricothyroidotomy with jet ventilation?

Answer 4

• Ensure patient supine, head extended to expose anterior neck
• Locate Cricothyroid membrane
• Connect 14 gauge needle to syringe half filled with saline
• insert at cricothyroid membrane, aspirate until air aspirated
• thread catheter over needle
• attach jet ventilator
  
  • Jet ventilatory provides 100% Oxygenation (SET TO 20 PSI)
  • Exhalation occurs passively through natural airway –> ensure upper airway is patent for gas to escape otherwise risk barotrauma!