Avan ivan ANAESTHESIA FOR CORRECTION OF STRABISMUS Dr

Avan – ivan

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

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

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

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

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

Anaesthesia �GA is usual �Adults �LA is ok

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.

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.

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

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

Effect of medications placed on eye Eye drops are readily absorbed through hyperemic, incised conjunctiva causing systemic effects � Phenylephrine is placed in the eye to produce mydriasis and haemostasis, �Phenylephrine absorption 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.

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

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.

Premed �Antisialogogue �Midazolam �PONV prophylaxis Droperidol 75 µg/kg ondasetron dexamethasone(0. 15 mg/kg) H 2 antagonists NO IM inj.

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. �ETCO 2 monitoring �Drapes ? !

U have IV access ? ? �Propofol, fentany l, �Rocuronium (0. 8 - 1 mg/Kg) �Sevo induction

GA �SPONTANEOUS Vs controlled �LMA Vs ET tube �LMA �Ease �Airway control in draped patients

ET tube �Preferably RAE tube(south polar ) with nondepolarizers �Maintenance �O 2: N 2 O: volatile �Air : O 2 : Volatile �Even fent + local + para may be enough

Effect of anaesthetic agents �Thiopentone – divergence of eyeballs �NDMR - divergence of eyeballs �Succinylcholine - Convergence

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

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.

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%.

Trigemino vagal refex �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

OCR PATHWAY

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.

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

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

Extubate deep Vs light �N 2 O : O 2 : agent ( no Halo ) �O 2 : agent �Narcotics , antiemetics and cut off anaesthetics �Cough, spasm – no difference �Preference of anaesthetist �LMA – good smooth awake extubation possible

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.

Retrobulbar – technique �A needle (22 -27 Gauge, 3 cm 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 -4 mls of local anesthetic solution is injected

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

Retrobulbar retro Peri

Complications – retrobulbar �Retrobulbar Hemorhage �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

Peribulbar

Peribulbar

Peribulbar

Peribulbar

USG guided retrobulbar block

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 levo bupivacaine also helpful.

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 opioid premedicated patients. �Oral midazolam 0. 5 mg/kg-better premedicant �Intraoperative use of metoclopramide 0. 1 -0. 15 mg/kg IV, droperidol 70 mic/kg, ondansetron 0. 1 mg/kg, and intravenous induction of anaesthesia by propofol reduce the incidence of PONV

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

Squint eyed thanks to you all

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

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

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)

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 nonophthalmic surgery; �patients present with open globes following penetrating eye injuries; �several drugs and procedures used in anaesthesia affect the IOP.

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 orbicularis oculi muscle, or retrobulbar hemorrhage will increase IOP.

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

IOP –drugs with no effect �Atropine, glyco pyrolate �Pethidine , alfentanyl �Atracurium , vecuronium �Desflurane , nitrous oxide

Anaesthetics - IOP increase �Ketamine �Scoline

Pharmacological reduction �IV Acetazolamide , decreased vitreous humour �Mannitol decreased aqueous humour �Topical Parasympathomimetics �β-Adrenoceptor antagonists Timolol reduces aqueous humour production through adenylate cyclase inhibition �Prostaglandin analogues -Increase aqueous humour drainage via uveoscleral route

IOP and P �Pressure �Procedures �Position

Open eye – problems � Smooth induction with muscle relaxation �Full stomach �intubation or LMA placement with care to avoid coughing and the hypertensive response to intubation; �ventilation to control Pa. O 2 and Pa. CO 2; �head up tilt with no obstruction to venous drainage by the tube tie; �smooth extubation with consideration of changing an endotracheal tube to a LMA prior to reversal to minimize the risk of coughing; �meticulous avoidance of postoperative nausea and vomiting.

Preanaes check up. �Routine preop check up. �Evidence of other injuries. �NPO status. �Routine investigations.

Premed �Oral sedatives- ok �Inj. PPI s or H 2 Blockers IV �IM better avoided – crying ↑ IOP. �EMLA for IV access. �Anti emetic and narcotic IV before induction.

Induction �Rapid sequence induction with thio and suxa ? ? �Suxa increase IOP �Benefits Vs risks. Propofol, NDPs and better to monitor NMJ and intubate. �No coughing or bucking �for blunting intubation response IV lignocaine 1. 5 mg/kg Clonidine 75 mic. gm Beta blocker labetolol 0. 03 mg/kg

Tips �Mask holding careful. Injure eyes �No airway obstruction �Obstructed breathing ↑ IOP �No ketamine �Be careful about OCR

�Intubate for full stomach patients �LMA with smooth in and out is other wise good. �Armoured tube if surgeon requests. � 15* head up tilt �Normal Pa. Co 2 �Normal BP

Extubation smooth �Narcotic and antiemetic before �IV lignocaine SOS. �Anxiety, airway obstruction, restlessness, full bladder, retching are all dangerous.

Thank you all