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Avan – ivan

Learn about types of strabismus, symptoms, anaesthesia considerations, effects of medications, premedication, monitoring, and anesthesia agents for strabismus correction surgery.

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Avan – ivan

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  1. Avan – ivan

  2. ANAESTHESIA FOR CORRECTION OF STRABISMUS Dr . S. Parthasarathy MD. DA. DNB., Dip.diab. MD(acu) , DCA, Dip. Software-statistics.

  3. Definition • Strabismus, often known as crossed eyes or squint, is a visual condition where gaze is misaligned • affects roughly 2% - 5% of the population.

  4. Classification : • Pseudostrabismus (Prominent epicanthal fold Hypertelorism, No treatment required) • Heterophoria (latent squint) • Heterotropia Concomitant squint Incomitant squint Strabismus can affect either one or both eyes, with an eye turning in, out, up or down

  5. 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

  6. SYMPTOMS • Deviation of eye (1°>2° or 2°>1°) • Loss of vision • Eye ache / strain ( ms. fatigue) • Diplopia (> towards paralytic ms.) • Spectacles / Refractive errors • Headache • Head tilt • Surgical correction is one of the modalities of correction

  7. Anaesthesia • GA is usual • Adults • LA is ok

  8. Pre anaes check up • Look for other diseases • There is a higher incidence of strabismus in trisomy 21 or Down syndrome, cerebral palsy, and hydrocephalus • Careful assessmemt of airway is mandatory before planning anaesthetic management.

  9. Progressive external ophthalmoplegia (PEO) Type of eye movement disorder. It is often the only feature of mitochondrial disease Weakness of ocular muscles – can come for repair Exercise intolerance,(cardiac decompensated heart) cataracts, hearing loss, sensory axonal neuropathy, ataxia, clinical depression, hypogonadism and parkinsonism.

  10. 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

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

  12. Effect of medications placed on eye   Eye drops are readily absorbed through hyperemic, incised conjunctiva causing systemic effects • Phenylephrineis placed in the eye to produce mydriasis and haemostasis, • Phenylephrine absorption can cause hypertension. arrhythmia and headache.  • To prevent systemic hypertension only 1 to 2% phenylephrine should be used and only one drop should be put into each eye.

  13. Effect of medications placed on eye • Adrenaline(2%) cause hypertension & arrhythmias • Timolol (B-blocker) causes bradycardia, hypotension & exacerbation of asthma • All routine examination , evaluation of systemic illness In adults for squint repair

  14. Phospoline iodide(echothiophate iodide • long acting anti-cholinesterase used in glaucoma prolongs suxamethonium induced muscle relaxation • A patient who has been treated with echothiophate iodide can retain low blood levels of pseudo cholinesterase for weeks or even months after discontinuing the drug • systemic effects of cyclopentolate hydrochloride include disorientation dysarthria and seizures.

  15. Premed • Antisialogogue • Midazolam • PONV prophylaxis Droperidol 75 µg/kg ondasetron dexamethasone(0.15mg/kg) H2 antagonists NO IM inj.

  16. Monitors • Pulse oximeter, temperature ,NIBP • The use of neuromuscular monitoring is strongly advised • ECG monitoring is mandatory. • It is essential to maintain normocarbia throughout the procedure. • ETCO2 monitoring • Drapes ?!

  17. U have IV access ?? • Propofol, fentany l, • Rocuronium (0.8- 1 mg/Kg) • Sevo induction

  18. GA • SPONTANEOUS Vs controlled • LMA Vs ET tube • LMA • Ease • Airway control in draped patients

  19. ET tube • Preferably RAE tube(south polar ) with nondepolarizers • Maintenance • O2: N2O: volatile • Air : O2 : Volatile • Even fent + local + para may be enough

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

  21. No scoline • Firstly, patients who have been given suxamethonium have a prolonged increase in the extra-ocular muscle tone, which interferes with the FDT. (This effect lasts roughly 15-20 minutes) • Secondly, patients undergoing correction of strabismus may be at increased risk of developing malignant hyperthermia

  22. forced duction test (FDT) • Eye immobile • To assess mechanical restriction to movement of the eye by moving it into each field of gaze • done by grasping the sclera near the corneal limbus with a pair of forceps. This test allows the surgeon to • differentiate between a paretic muscle and a mechanical restriction limiting eye movement.

  23. oculo-cardiac reflex- OCR • Aschner and Dagnini in 1908 • Pressure on the globe , traction of extraocular muscles retrobulbar block and retrobulbar hemorrhage • manifested as bradycardia, but it also may appear as bigeminy, ectopic beats, nodal rhythms, atrio ventricular block, or asystole. • medial rectus muscle or even periosteum • The reported incidence between 32% and 82%.

  24. Trigeminovagalrefex • The afferent limb is from orbital contents to ciliary ganglion to ophthalmic division of the trigeminal nerve to the sensory nucleus of the trigeminal near the fourth ventricle. The efferent limb is via the vagus nerve to the heart

  25. OCR PATHWAY

  26. OCR • Tends to be more marked with sudden and sustained traction compared to slow, gentle, progressive traction • continuous monitoring of the electrocardiogram (ECG). • Fatigue of the OCR usually occurs with subsequent stimulation.

  27. OCR • Glyco prevents • If it happens , atropine IV 7 µg/kg increments • Surgeon stops traction • Assess depth of anaesthesia • Maintain normocapnia, normoxia • Local infiltration

  28. 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

  29. Extubate deep Vs light • N2O : O2 : agent ( no Halo ) • O2 : agent • Narcotics , antiemetics and cut off anaesthetics • Cough, spasm – no difference • Preference of anaesthetist • LMA – good smooth awake extubation possible

  30. Regional anaesthesia • Retrobulbar • A retrobulbar block is a regional anesthetic nerve block into the retrobulbar space, • the area located behind the globe of the eye. • Injection of local anesthetic into this space constitutes the retrobulbar block.

  31. Retrobulbar – technique • A needle (22-27 Gauge, 3cm long) is inserted at the inferolateral border of the bony orbit • Directed straight back until it has passed the equator of the globe. • It is then directed medially and cephalad toward the apex of the orbit. • Occasionally a 'pop' is felt as the needle tip passes through the muscle cone delineating the retrobulbar space. • Following a negative aspiration for blood, 2-4mls of local anesthetic solution is injected

  32. Retrobulbar • This injection provides akinesia of the extraocular muscles by blocking cranial nerves II, III, and VI, thereby preventing movement of the globe. • Cranial nerve IV may be spared since it lies outside the muscle cone. • It also provides sensory anesthesia of the conjunctiva, cornea and uvea by blocking the ciliary nerves

  33. Retrobulbar retro Peri

  34. Complications – retrobulbar • RetrobulbarHemorhage • Central Retinal Artery Occlusion • Puncture of the Posterior Globe • Penetration of the Optic Nerve • Inadvertant Brain Stem Anesthesia • A needle longer than 32 mm must never be used in • the lateral orbit or 25 mm in the medial orbit

  35. Peribulbar

  36. Peribulbar

  37. Peribulbar

  38. Peribulbar

  39. USG guided retrobulbar block

  40. Post operative pain management • Limbal incision more painful than fornix incision • important to reduce pain and discomfort in children. • rectal paracetamol or diclofenac suppositories are commonly used for this purpose. • Preoperative subtenon's instillation of levobupivacaine also helpful.

  41. Post operative nausea and vomiting • Very common following strabismus correction. • secondary to altered visual perception or an oculoemetic reflex, which is analogous to the oculocardiac reflex. • more common in opioidpremedicated patients. • Oral midazolam 0.5 mg/kg-better premedicant • Intraoperative use of metoclopramide 0.1-0.15mg/kg IV,droperidol 70 mic/kg,ondansetron 0.1mg/kg, and intravenous induction of anaesthesia by propofol reduce the incidence of PONV

  42. The anaesthetic concerns-summary • controversial use of suxamethonium , halo • systemic effect of topical medications, • associated congenital mal formations & difficult airway, • Proseal LMA • propensity for malignant hyperpyrexia • Oculo cardiac reflex, • high incidence of post operative nausea and vomiting • need for post op analgesia

  43. Squint eyed thanks to you all

  44. ANAESTHESIA AND IOP • IOP is the pressure exerted by the contents of the eye upon the cornea and sclera of the globe. • The sclera is inelastic, making compliance of the globe low -- means ?? • The volume of the globe is principally determined by the aqueous humor and the blood vessels of the eye

  45. IOP causes what ?? • Increased IOP • retinal ischemia and corneal opacification. • Decreased IOP • retinal detachment and vitreous hemorrhage

  46. Normal IOP differences • Normal IOP is 15 ± 5 mm Hg in the sitting position maintained within this narrow range. • (1) changes in body position (+1 mm Hg supine), • (2) diurnal rhythm (2–3 mm Hg), • (3) blood pressure oscillations (1–2 mm Hg), and • (4) respiration (deep inspiration decreases IOP by 5 mm Hg)

  47. The importance of IOP for anaesthetists • patients with acutely or chronically raised IOP may present for corrective surgery; • patients with chronically raised IOP present for non-ophthalmic surgery; • patients present with open globes following penetrating eye injuries; • several drugs and procedures used in anaesthesia affect the IOP.

  48. IOP increase • obstructed airway during induction of or emergence from general anesthesia will increase venous congestion in the ophthalmic veins • Coughing, Valsalva maneuvers, or straining can increase IOP to 30–40 mm Hg. • Endotracheal intubation is another potent stimuli for increasing IOP. • External pressure from face mask, fingers, orbital tumors, contraction of the orbicularisoculi muscle, or retrobulbar hemorrhage will increase IOP.

  49. Drugs and decreased IOP • Opioids 20 % approx • Midazolam _ 25 % • Pentothal propofol approx 30 % • Inh. Agents 30 % • Maximal decrease – dexmedetomidine – 40 %

  50. IOP –drugs with no effect • Atropine, glycopyrolate • Pethidine , alfentanyl • Atracurium , vecuronium • Desflurane , nitrous oxide

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