anesthesia for ophthalmic sx edit
DESCRIPTION
โดย : นพ. ณัฐพงค์ ฉัตรศรีวงศ์ วิสัญญีแพทย์ รพ.เมตตาประชารักษ์ (วัดไร่ขิง)TRANSCRIPT
นพ . ณั�ฐพงค์ ฉั�ตรศร�วงศว�สั�ญญ�แพทย์ รพ.เมตตาประชาร�กษ์ (ว�ดไร ขิ�ง)
OculoplasticSquintCorneaLensGlaucomaVitreoretinalNeuro-
ophthalmology
Local anesthesia Topical anesthesia Regional anesthesia
General anesthesiaOphthalmic surgery
Local Local anesthesiaanesthesia
Local Local anesthesiaanesthesia
General General anesthesiaanesthesia
VSVS
Many benefits Physiological disturbance PONV Economic
Topical / Regional anesthesia
Non-invasiveVirtually no complications
Challenging operating conditions – no akinesia
Increasingly popular for phacoemulsification cataract surgery
Careful patient selection Co-operative Not distressed Straightforward surgery Must be able to lie supine and still Not claustrophobic
Sedation (Anesthesiologist stand-by)
IV access / supplementary O2
Which LA? Proxymetacaine / amethocaine Preservative free preferred ± topical NSAID and mydriatic
20-30 min before surgeryTwo to three drops every 5 minutes
Cornea is avascular – once absorbed LA remains for about 30 min
Supplemented by incremental injection
What about this choice?
Advantages Day cases Good akinesia and Anesthesia Minimal effect on IOP Minimal equipment required
Disadvantages Not suitable for all patients Complications Skill of Surgeons/Anesthesiologists Unsuitable for certain types of surgery
Orbit – shape of irregular pyramid Base at front Axis points
posterio-medially towards skull
Globe lies in anterior part of orbit
- sits high and lateral
Four rectus muscles arise from the back of orbit
Insert into the globe just forward of equator
Form a cone - boundary
between two
compartmentsCENTRAL(retrobulbar)
PERIPHERAL(peribulbar)
Within the cone Optic nerve Opthalmic artery & vein Ciliary ganglion Oculomotor nerves
Sensory supply to orbit from opthalmic division Trigeminal nerve enters the orbit through superior orbital
fissure
Peribulbar block (Pericone)Retrobulbar block (Intracone)
Sub-Tenon’s block
Comfort Assistant providing
reassurance O2 saturation,
ECG, BP monitoring
Right angled screen providing O2
Intravascular injectionAnaphylaxisHemorrhageSubconjunctival edemaPenetration / perforation of the globeCentral spread (sub-arachnoid)Optic nerve atrophy
2001 Guidelines (RCA & College Of Ophthalmologists) Trained staff Surgeons – topical / sub-conjunctival /
sub-Tenon – without Anesthesiologist Anesthesiologist & iv access when
retrobulbar / peribulbar Anesthesiologist in charge when
sedation used
Indications: Patient refusal Children / learning difficulties /
movement disorders Major / lengthy procedures Inability to lie still / flat Claustrophobic
Patients at extreme age Old – medication, confused, deaf, blind,
with co-morbid like DM, CAD, HTN, COPD Young – congenital anomalies, temp. &
fluid balance
Opthalmic drugs Timolol – B-Blocker Phospholine iodide – anti-cholinesterase
Normally 10-20 mmHg
Must be controlled when operating within the globe
IOP impaired op. conditions expulsion of intra-ocular contents
Mild IOP improved op. conditions
Increasing External pressure e.g.
face mask Venous pressure Arterial pressure Hypoxia Hypercarbia Succinylcholine,
Ketamine Laryngoscopy Coughing
Decreasing Venous pressure Arterial pressure Hypocarbia IV induction agents NDMRD Aqeous volume
(acetazolamide) Vitreous volume
(mannitol)
Careful with face mask No ketamine Laryngoscopy after completely
paralyzed 4% Xylocaine topical anesthesia at
vocal cord Head up tilt
Monitoring: ECG, oximeter, capnograph and peripheral nerve stimulator if available
Continue volatile agent until spontaneous respiration is resumed after reversal
Anti-emetic may be administered No food/drink for 3 hours to reduce the
possibility of aspiration of gastric contents
★ If no muscle relaxants and patient breathes spontaneously, the depth of anesthesia must be increased to prevent coughing or straining against the tube.
Avoid nitrous in vitreoretinal surgery Bubbles of sulphurhexafluoride (SF3)
Emergence without coughing Deep extubation Lignocaine on cords Bolus lignocaine/ propofol beforehand
Scoline or not??
Traction on EOM may cause sudden and profound bradycardia via oculocardiac reflex mediated by CN X
Occasionally seen during other forms of eye surgery e.g. retinal detachment
Prevention Moderated by LA (abolish afferent arc) Avoid hypoxia/hypercapnia (sensitizes the
reflex) Prophylactic anticholinergic ★esp in children
Management STOP stimuli at once Ensure adequate ventilation Ensure sufficient anesthetic depth If needed, atropine 0.02 mg/kg IV
Is atropine useful?Is atropine useful? Controversial 0.4 mg IM as a premedicant has no
vagolytic effect after 60 min and is of no value in preventing or treating OCR
0.4 mg IV is effective for 30 minutes in preventing bradycardia associated with the OCR
Doses >0.5 mg IV can cause tachycardia★
Examination in children can often be provided satisfactorily via a face mask
If the naso-lacrimal duct is to be irrigated Intubation or Positioning the patient with a pillow
under the shoulders
KetamineKetamine can also be used but pre-medication with atropineatropine is essential to prevent laryngospasm caused by excessive secretions.
If sedation is required Midazolam (0.5 -1 mg) with Fentanyl 25 – 50 mg or Propofol 20 mg.
Peribulbar block is advisable when axial length is less than 26mm and patient can lie flat & still.
Haelan (Sodium Hyaluronate) is injected at the time of incision to maintain the shape of anterior chamber and controls the vitreous bulge.
Cataract Surgery can be performed under Regional Anesthesia without discontinuing anticoagulant therapy (Prothrombin Time 1.5 times control).