Download 1 MB - squint MGMC - Anesthesia Slides, Presentations and

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)
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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
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(> 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
 CNS infection
Seizures
 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
Vaso vagal
episodes
 Sudden unconsciousness
 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 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.
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(0.15mg/kg)
H2 antagonists
NO IM inj.
Monitors
 Pulse oximeter, temperature ,NIBP
 The use of neuromuscular monitoring is strongly
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advised
ECG monitoring is mandatory.
It is essential to maintain normocarbia throughout
the procedure.
ETCO2 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
 O2: N2O: volatile
 Air : O2 : 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
 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
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, 3cm long) is inserted at the
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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
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 0.1-0.15mg/kg
IV,droperidol 70 mic/kg,ondansetron 0.1mg/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
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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
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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
 Pressure
 Pressure
 Procedures
 Position
Open eye – problems
 Smooth induction with muscle relaxation
 Full stomach
 intubation or LMA placement with care to avoid coughing
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and the hypertensive response to intubation;
ventilation to control PaO2 and PaCO2;
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 H2 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 75mic.gm
Beta blocker labetolol 0.03mg/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 PaCo2
 Normal BP
Extubation smooth
 Narcotic and antiemetic before
 IV lignocaine SOS.
 Anxiety, airway obstruction,
restlessness, full bladder, retching are
all dangerous.
Thank you all