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Dr. Rajendra Prasad KoduriSpecialist - Dept. of Anesthesia

Mafraq hospital.Review article from the European Journal of Anesthesiology- EJA

September 2008.

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Introduction The most common procedure in eye surgery is cataract

surgery

with or without sedation followed byexamination under anesthesia EUA for the pediatricpopulation (sedation- sedoanalgesia to generalanesthesia).

Trends have shiftedfrom G/A with ETT LMA Regionalanesthesia( retro bulbar/ peribulbar & subtenonblocks topical anesthesia.

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Intro-contd.What are the issues :Anxietyeye/pain/discomfort/visual experiences -

16%

counselling is of help but not widely practiced.

Anxiety induces catecholamine release and can widelyaffect cardiovascular co-morbidity and diabetes elderly patient.

Patient satisfaction surveys showed 96.8 % weresatisfied , 2.3 % were somewhat dissatisfied and 0.9were dissatisfied- with a strong correlation betweendissatisfaction and younger age , shorter procedures,post-op pain , nausea and vomiting and awareness.

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Management of eye surgery under L/A. RCA-RCO (UK) & Agency for Healthcare Research and

Quality (AHRQ) USA have published guidelines.

Goals

anxiolysis & per-operative/ post op painrelief.

Objectives- block procedure as painless aspossible/anesthetise the globe and conjuctiva

produce akinesia of the eyeball and to reduce theintraocular and intraorbital pressures.

Advantages-fewer systemic side effects/ easycommunication with patients during the procedure.

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Contra indications to local anesthesia.

Patient uncooperative especially mentally impaired.

Communication is difficult- language barrier/ deaf.

Those who have involuntary movement disorders.

Cardiovascular co-morbid patient with Grade 3dyspnea/ orthopnea.

Uncontrolled coughing or sneezing.

Severely anxious patient or claustrophobic patient. Undergoing bilateral surgery.

Difficult and prolonged surgery is likely.

Preference by patient / surgeon/ anesthetist.

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Local anesthesia vs.Topical anesthesia.

Topical anesthesia may not provide pain control ascomplete as needle based techniques.

Avoids serious complications such as retrobulbarhemorrhage, globe damage and spread of localanesthetics to unusual locations leading to lifethreatening complications.

Akinesia of the eye is not ensured & coupled with theinadequate pain control and the activation of thecentral reflexes may stimulate nausea and vomiting.

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sedation vs. sedo-analgesia.

Patient preference stats show that 72% prefer a blockcompared to topical anesthesia and 66% preferred oralsedation to intravenous sedation.

With iv sedations there were more interventions forheart rate rhythms and arterial oxygen desaturations.

Katz et al found that sedation alone reduced painduring surgery but 3.4% of the patients had intra-operative pain and 2.7 % were dissatisfied.

Drowsiness was seen in 2.7% and nausea and vomiting

were a problem in 4.1%. The addition of an opiodsignificantly reduced the pain during surgery /reduced the drowsiness/and increased the patientsatisfaction.

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Sedo-analgesia. Goals of sedo-analgesia --- induce drowsiness ,alleviate

fear ,anxiety and pain without loss of verbalcommunication.

Sedation must be achieved with preservedcardiovascular stability, little or no respiratorydepression, good operating conditions with a rapid

return to pre-op mental and physical state and littleresidual effects.

The ASA has quantitated various levels of sedationwith the help of scoring systems.

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The sedation scales. The Ramsey sedation scale.

Response to command score

Awake , anxious, agitated or restless 1

Awake ,co-operative, oriented and tranquil 2

Drowsy with response to commands 3

Asleep ,brisk response to glabellar tap or loud noise. 4

Asleep, sluggish to respond to stimulus. 5

No response to firm nail bed pressure or noxiousstimuli.

6

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Observer assessment of awareness,

sedation scale- OASSRESPONSIVENESS SPEECH SCORE

Responds rapidly to name in normaltone.

normal 5

Lethargic response to name spokenloudly.

Mild slowing 4

Responds only to repeated ,loud noise. Slurred 3

Responds only after mild physicalcontact.

Few recognisedwords.

2

Does not respond to mild physicalcontact.

1

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UMSS- University of Michigan sedation

scale.Sedation response score

Awake and alert 0

Minimum sedation Tired/ sleepy&appropriate responses.

1

Moderate sedation Somnolent /sleepy butarousable to simplecommand.

2

Deep sedation Deep sleep arousable tosignificant physicalstimuli.

3

Unarousable 4

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Drugs used for sedation. Ideal sedative drug should have rapid onset and short

duration of action, does not cumulate, is non toxic, hasa favorable therapeutic index and has predictable sideeffects.

Do we have it ????----the answer is no.

What are our options?

Benzodiazepines, iv induction agents ,AAA such asdexmed and clonidine & opiates.

The iv route is the most easily adjustable and can beused as PCA- TCI-PCS or bolus injections.

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The benzodiazepines. Excellent amnesia, anxiolysis and hypnosis. Oral and intravenously PCS. Residual effects reversed when required.

Midazolam is short acting with K of 90 minutes and has theadvantage of rapid onset & no venous irritation. Suggested iv doses are 10-15 micro /kg. and suggested set in time

for sedation in the elderly is 5-10 minutes with dose reductionsby 30% in patients over 60 yrs.

Morley et al and Irwin et al ( Journal of anesthesia and intensive

care 1997/ anesthesia -2000) compared PCS Midazolam 100microgram bolus with PCS propofol 3.3 milligrams bolus andreported equal reductions in anxiety by the Ramsey sedationscores but concluded that Midazolam prevented increases inblood pressure with the insertion of block.

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The intravenous induction agents. Propofol suitable for infusion and sedation. The

mean target levels for sedation are 2.2 microgm/ml bythe TCI.

In the PCS study elderly day care surgery patients over60 yrs received self administered propofol in 0.25mg/kg bolus injections with a lock out of 3 mts. Thetotal # of patients using PCA was 14/20 & only 8/ 20used the PCA once and 6/20 used it

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The iv. induction agentscontd. KETAMINE is another drug useful for sedation.

Cardiovascular stability and no effect on respiration.

Low dose ketamine 10-20 mg along with propofol 10-20 mg or midazolam 10 microgram/kg providedsuperior analgesia and patient comfort than witheither drugs used alone.

no effects on intraocular pressure but the incidence ofnausea, vomiting are higher than the other groups.

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Analgesic agents. Fentanyl is a potent narcotic analgesic with a duration of

action of about 30 minutes after a single dose. Aydin andcolleagues showed that PCA fentanyl in a loading dose of

0.7 microgm/kg followed by 5 micro bolus/ 5mt lockoutintervals has supplemental analgesic effects with topicalanalgesia and increased patient / surgeon satisfaction.

Alfentanil is a more rapid and shorter acting analogue of

fentanyl. The incidence of respiratory depression is high inthe elderly patients. The suggested dose is 20 micro/kgand has been used for placement of RB blocks.

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Analgesic agents contd. Remifentanil is the latest analogue of fentanyl and has

unique degradation characteristics with k1/2 of 3-10minutes.

Produces intense analgesia with a predictable duration ofaction.

Profound respiratory depressant and supplemental oxygenshould be given.

May cause profound fall in BP/ HR and must be used withcaution in the elderly.

The suggested regimes by Swedish coworkers is 3micro/kg/hr +/_ 1 micro along with propofol 70micro/kg/hr with no changes in hemodynamics/respiratory parameters and good pain relief.

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Other agents. Dexmeditomidine is a AAA and has been used for

ophthalmic sedation with good results. A suggestedregime is 2.5 microgm/kg bolus in 10 mts followed by 0.4microgm/kg /hr until the last suture without undue

hemodynamic fluctuation. (s/e- hypotension) Clonidine is a centrally acting AAA that reduces

sympathetic outflow from the brain secondary to itsstimulating effects on the vasomotor centre.

Clonidine used in the dose range of 0.5-2.0 microgm/ kgcan be added to the local anesthetic itself for the blockcauses direct reductions in IOP, sedative effects andproduces increased duration of akinesia and analgesia withdecreases in both HR and SVR.

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Practical and simple methods of drug

administration for ophthalmic sedation.Methods ofadministration

Drug Dose regimens

Intermittent injection. Midazolam

PropofolKetamineFentanylAlfentanilDexmeditomidine

1 mg increments or 0.015micrograms/kg10-20 mg titrated dose10-20 mg25-50 micrograms20 microgm/kg2.5 microgm/kg

Patient controlledsedation.

MidazolamPropofol

0.1 mg bolus0.25 mg /kg bolus with alockout interval of 3 mts.

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A brief review of the literature since 1953 1 slide

The cleveland clinic guidelines for procedural sedationnot specific to eye surgery-----------------2 slides.

A total of 22 slides for the presentation.