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ANAESTHESIA - STRABISMUS SURGERY

ANAESTHESIA - STRABISMUS SURGERY. www.anaesthesia.co.in. email: anaesthesia.co.in@gmail.com. Strabismus. Misalignment of the visual axes of the two eyes Classification : Pseudostrabismus Heterophoria Heterotropia Concomitant squint Incomitant squint. Pseudostrabismus.

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ANAESTHESIA - STRABISMUS SURGERY

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  1. ANAESTHESIA - STRABISMUS SURGERY www.anaesthesia.co.in email: anaesthesia.co.in@gmail.com

  2. Strabismus Misalignment of the visual axes of the two eyes Classification : Pseudostrabismus Heterophoria Heterotropia Concomitant squint Incomitant squint

  3. Pseudostrabismus Prominent epicanthal fold Hypertelorism No treatment required

  4. Heterophoria (latent squint) Types – Eso / Exophoria Hyper / Hypophoria Cyclophoria Treatment – Refraction correction Orthoptic exercises Prism in glasses Surgery

  5. Heterotropia Concomitant strabismus Convergent Divergent Vertical Paralytic strabismus

  6. Strabismus • Process starts at 3-4 mts of age; completed at 6 yrs • Usual presentation at 1-6 yrs • If proper stereoscopic visual development is to proceed Surgical intervention must occur by 4 mts age

  7. What the patient tells you? • Deviation of eye (1°>2° or 2°>1°) • Loss of vision • Eyeache / strain ( ms. fatigue) • Diplopia (> towards paralytic ms.) • Spectacles / Refractive errors • Headache • Head tilt PONV

  8. Whatyou need to know? • Confusion / blurring of words • Photophobia • Alternating or intermittent squint • Weakness or drooping of eyelids by evening (MG) • Vertigo • Motion sickness PONV

  9. Past history of • Head injury • CNS infection • ICSOL/ CNS surgery • Influenza or measles in childhood • Prematurity or respiratory distress at birth • Muscle weakness / Myopathy • Endocrine disorder Seizures

  10. …….Past history MH • Anaesthetic exposure in past • Black outs • Sudden unconsciousness • β antagonists Vaso vagal episodes OCR

  11. …….Past history • TB / DM / HTN (vascular lesions – CVA) • Asthma / Allergy • Chest pain / Palpitations • Alcohol / Smoking

  12. Family History • H/o anaesthetic exposure to family member. MALIGNANT HYPERTHERMIA

  13. Examination • General examination • Vitals • Systemic examination (CNS) • Airway examination • Ophthalmological examination

  14. Ophthalmic examination Abnormal tilt – Anatomy altered • Head position • Eyebrows, eyelids, cornea, lens • Deviation of eyeglobe (Exo / Esotropia) • Pupils (direct / consensual) • Visual acuity

  15. Bedside tests • Cover test • Cover uncover test • Alternate cover test • Hirschberg corneal reflex Latent squint Intermittent / alternating squint

  16. Goals of treatment • Good cosmetic correction • Improve visual acquity • Maintain binocular single vision

  17. Treatment modalities • Spectacles (refractive correction) • Occlusion therapy • Orthoptic exercises (preop) • Surgery

  18. Strengthening Weak muscle Resection Tucking /plication Advancement Weakening Strong Muscle Resection Marginal myotomy Myectomy Surgery

  19. Anaesthetic Concerns • Oculo-cardiac reflex • Oculo-respiratory reflex • Postoperative nausea and vomiting • Malignant hyperthermia • Systemic effects of ophthalmic drugs • Association with syndromes – Aperts, Crouzons

  20. Systemic effects of ophthalmic drugs • Usually only antibiotic is given preop. • Phenylephrine • Tropicamide, cyclopentolate • Ecothiophate • Epinephrine • Timolol

  21. GA Vs RA

  22. What is with Succinylcholine? Inc. incidence masseter spasm halothane and succinylcholine in pts with squint Frequent incidence of Masseter spasm after Succinylcholine in squint pts Malignant Hyperthermia Ass. With myopathy ? Avoid Succinylcholine and halothane

  23. ……….. Succinylcholine? Extraocular muscles Cells Multiple NMJs Abnormal forced duction test (20 min) Succinylcholine Repeated depolarizations Prolonged contracture Increased muscle tone

  24. Forced Duction Test • Distinguish paralytic and mechanical restriction of movements (Graves ds) • Surgeon grasps sclera near limbus and tests full range of movt. in all quadrants • Positive – mechanical restriction • Negative – EO ms palsy • May influence type of strabismus surgery

  25. Forced Duction Test under GA • Wait 15 – 20 min after succinylcholine admn • Non depolarising muscle relaxants • Intubate and maintain on deep inhalational anesthetic till FDT → Institute NM blockade

  26. Preoperative Orders • Consent • NPO orders • Peripheral IV access -20G cannula, RL • Sedative (BZD); H2 antagonists • Antiemetics – Ondansetron (0.1mg/kg); dexamethasone(0.15mg/kg) • Inj. Atropine 0.02mg/kg (iv > im) • Inj. Lidocaine 1.5mg/kg iv

  27. Monitors • Pulse oximeter • NIBP • ECG • Temperature • EtCO2

  28. Induction & Maintenance • Inj. Propofol / Thiopentone • Inj. Rocuronium (0.6-1.0mg/kg) • RAE south polar tube • M/W O2 + N2O + Isoflurane / propofol infusion

  29. Oculocardiac reflex • Trigeminovagal reflex response manifested as cardiac arrythmias & hypotension & may be elicited by pain, pressure and manipulation of eyeballs.

  30. Long and short ciliary nerves (V th ) ↓ Afferent limb Ciliary ganglion OCR ↓ Gasserian ganglion Efferent limb Impulses from brain stem via X N HEART

  31. OCR Triggers • Pressure on globe • Traction – EOM, conjunctiva & other str. • Ocular trauma / retrobulbar haematoma • Performing retrobulbar block • Manipulation – eyelid stretch • Ocular pain • Hypoxemia and Hypercarbia

  32. OCR Medial Rectus – • Manipulated most often • Less accessible , requires more force for exposure • Attachment : pain sensitive meninges around optic nerve THEORY More acute the onset and stronger & more sustained the traction , the more likely OCR is to occur

  33. Bradycardia Junctional rhythm Atrial ectopic AV block Ventricular bigeminy Multifocal PVC Idioventricular rhythm Ventricular tachycardia Asystole OCR Arrythmias

  34. OCR Prevention • Gentle surgical manipulation • Adequate depth of anaesthesia • Normal PaO2, PaCO2, pH • ECG monitoring • IV atropine 0.02mg/kg ; glyco. 0.01mg/kg ( single dose protect 30 min) • Retrobulbar block?

  35. OCR Treatment • Stop surgical manipulation • Assess normocapnia & normoxemia • Optimize depth of anesthesia • Returns to NL 20 s • Arrythmia persists – Inj. Atropine 0.007mg/kg increments Inj. Lignocaine 1.5mg/kg

  36. Oculo-Respiratory Reflex • Shallow breathing , ↓RR & apnea Long and short ciliary nerves (V th ) Afferent limb Ciliary ganglion Sensory nucleus V N ↓ Efferent limb ↓ Pneumotaxic centre in Pons and Medullary Respiratory Centre

  37. Oculo-Kinetic Reflex Positional information from vestibular apparatus Sensory input from Visual apparatus Nausea & Vomiting Disturbed CNS PROCESSING

  38. ↓ impulses from extra ocular muscles vestibular nuclei III, IV,V MLF in reticular formation close proximity to vomiting centre nausea & vomiting ↓ ↓ ↓

  39. PONV • Decrease opioids • Propofol ; volatile anesthetics • Decrease or avoid N2O TIVA • Ondansetron / dexamethasone/ droperidol • NGT aspiration • Gentle surgical manipulation • Adequate hydration • Lidocaine infiltration

  40. Postoperative • Analgesia - Inj meperidine 10-25 mg iv Inj ketorolac 30 mg iv/ im Limbal incision more painful than fornix incision • Oxygenation • W/F OCR, ORR, PONV • Monitor 4 hrs

  41. Effect of anaesthetic agents • Thiopentone – divergence of eyeballs • NDMR - divergence of eyeballs • Succinylcholine - Convergence

  42. Thank You

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