Anesthesia for Transphenoidal Hypophysectomy

1. Anesthesia for TransphenoidalHypophysectomy

2. Introduction • Tumours of pituitary gland represent approximately 10% of diagnosed brain neoplasms. • Transsphenoidal resection of pituitary brain tumours may account for as much as 20% of all intracranial operations performed for primary brain tumours.

3. Objectives • Anatomy and physiology • Pituitary pathology • Different approches for hypophysectomy • Perioperativecosiderations.

4. Anatomy and Physiology of Pituitary Gland

8. Antidiuretic hormone(ADH) Oxytocin

9. Pituitary Pathology

10. Pituitary Adenomas • Pituitary adenomas can be classified into: • Microadenomas (<1 cm) • Macoadenomas(>1 cm) • Further classification : • Non functioning tumors • Functioning tumors

11. Non Functioning Adenomas • More likely to be macroadenomas • Symptoms related to mass effect • Most common : • Chromophobe adenomas • Craniopharyngiomas • Meningiomas

12. Functioning Adenomas • Excess of one or more of the anterior pituitary hormones. • Prolactinomas followed by GH and ACTH secreting adenomas. • Adenomas secreting thyrotropin or FSH and LH are rare.

13. Adenomas: Clinical Disease and Medical Therapy

14. Pituitary surgery

15. Preoperative Evaluation

16. Preoperative Evaluation • Visual function • Signs and symptoms of raised intracranial pressure • Endocrine studies; and the effects of hormonal hypersecretion,hyposecretion • Co-morbidities, particularly in acromegaly or Cushing’s syndrome • CT & MRI

17. Mass effect

18. Mass effect

19. Prolactinoma • Prolactinomas are the most frequently observed type of hyperfunctioning pituitary adenoma • Represent 20%–30% of all clinically recognized tumours. • More than 90% of patients respond to medical therapy with a dopamine agonist such as bromocriptine and thus few patients present for surgery

20. Clinical Features of Acromegaly

22. Clinical Features of Cushing

24. Hypopituitarism • Low levels of peripheral hormones, not associated with high pituitary tropic hormones. • Pituitary apoplexy: present with sudden headache, loss of vision, loss of consciousness and panhypopituitarism, requiring urgent surgery. • Requires glucocorticoid replacement • Thyroxine replacement is also required (50–150 ug daily). • Perioperatively, these patients are extremely sensitive to anaesthetic agents, and pressor agents may be needed to maintain blood pressure.

25. MEN syndromes

26. Intraoperative Issues

27. Intraoperative Issues • General issues : • Optimization of cerebral oxygenation • Maintenance of hemodynamic stability • Provision of conditions that facilitate surgical exposure • Prevention and management of intraoperative complications • Rapid, smooth emergence.

28. Intraoperative Issues • Surgical Approach • The pituitary fossa can be approached using the transsphenoidal, transethmoidal or transcranial route • The transsphenoidal route is preferred for all but not the largest of tumours • Transsphenoidal access to the pituitary fossa is obtained using a sublabial or endonasal approach

29. Surgical approach

30. Introperative Issues • Hormone replacement • Preoperative hormone replacement therapy should be continued into the operative period • In general, All patients with Cushing’s disease require glucocorticoid cover.

31. Perioperative Steroid Management Pituitary adenoma for surgery 0800 hours cortisol and short ACTH 1–24 (synacthen) Normal Abnormal (cortisol >550 nmol/L) • The patient should be given supraphysiologicalglucocorticoid cover for 48 h • Hydrocortisone 50 mg i.v. 8-hourly on day 0 • 25 mg i.v. 8-hourly on day 1 • 25 mg i.v. at 0800 hours on day 2 No PerioperativeGlucocorticoid Cover 0800 hours cortisol 0800 hours cortisol for 1-3 d 0800 hours cortisol for 3-6 d

32. Perioperative Steroid Management 0800-h Cortisol level(nM) >450 100–250 250–450 <100 10–20 mg, single morning dose Stress only, 0800-h Cortisollevel Day 7 <350 nM >350 nM ITT or metyrapone 10-14 d or 4-6 wks Abnormal Normal 15–30 mg/d (maintenance) No replacement

33. Intraoperative Management General EndotrachealAnesthesia Is Indicated. • Airway management. • Anesthetic techniques • Operative techniques • Intraoperative complications. • Emergence and recovery

34. Prepare for Difficult Airway

35. Airway Management • Four grades of airway involvement: • Grade 1-- no significant involvement • Grade 2-- nasal and pharyngeal mucosa hypertrophy but normal cords and glottis • Grade 3-- glottic involvement including glotticstenosis or vocal cord paresis • Grade 4-- combination of grades 2 and 3, i.e. Glottic and soft tissue abnormalities

36. Airway Management • Airway management and tracheal intubation proceed uneventfully in the majority of patients if large face masks and long-bladed laryngoscopes are used • Fibreoptic intubation should be considered in patients in whom difficult airway management is predicted • Intubating laryngeal mask airway has also been used successfully • Equipment for tracheostomy should be available if airway changes are advanced (recommended for grades 3 and 4)

37. Airway Management • Reinforced orotracheal tube is recommended. • Positioned in the left corner of the mouth • Throat pack is then inserted. Prevent bleeding into the glottic region during surgery, but also entry of blood and secretions into the stomach which may precipitate postoperative vomiting

38. Monitoring Standard Monitors

39. Positioning • Supine • Head elevated • Patient closer to the right hand side of the table • Neck tilted laterally to the left, slightly extended and secured in a mayfield clamp.

40. Positioning

42. Preparation of Nasal Mucosa • Agents: lignocaine with adrenaline • For suppressing the hemodynamic response to nasal infiltration with adrenaline-containing solutions: • Labetolol, • Alpha-antagonists (such as phentolamine), • Beta-blockers • Vasodilators (such as nitroglycerin or sodium nitroprusside). • Deepening anesthesia or blousing a shortacting, potent opioid (such as alfentanil or remifentanil) • Bilateral maxillary nerve blocks

43. Transsphenoidal Approach to the SellaTurcica for Pituitary Surgery

45. Intraoperative Management • Anesthetic Technique • Inhaled agents sevoflurane, desflurane and isofluranehave all been shown to increase lumbar CSF pressure. • Whether an inhalational or intravenous technique is employed, short-acting agents should be utilised to facilitate rapid recovery Postoperative Airway Maintenance Is An Issue

46. Intraoperative Management • Analgesia • Short-acting, potent opioids, such as Remifentanil. • Longer acting opioids (towards the end of surgery). • Paracetamol • Non-steroidal anti-inflammatory drugs (postoperative haematoma) • Tramadol (less effective and more sedation)

47. Intraoperative Management • Controlled hypercapnia(to a maximum PaCO2 of 60 mmHg). However, it is preferred to maintain high-normocapnia (40–45 mmHg). • Lumbar cerebrospinal fluid catheter. a forced Valsalva can often be sufficient. Typical neuroanestheticmaneuvers designed to reduce ICP in these cases because they make the pituitary retreat upward out of the sella

48. Intraoperative Complications • Venous air embolism • Aspiration of air from a multi-orifice air aspiration catheter (if in situ). • Administration of 100% oxygen • Application of internal jugular vein pressure bilaterally • Saline irrigation of the wound. • Haemostasis of open vessels are crucial

49. Intraoperative Complications • Hemorrhage from carotid artery damage. • Pseudo-aneurysm and carotid-cavernous fistula formation .

50. Emergence From Anaesthesia Smooth and rapid emergence from anaesthesia is essential to allow early neurological assessment and maintenance of stable respiratory and cardiovascular variables. • At the completion of surgery, the oropharynx should also be suctioned meticulously. • Removal of pack