TOPIC

EFFECT OF DEXMEDETOMIDINE AS AN ADJUVANT TO EPIDURAL ROPIVACAINE

0.75%

DR.Rajaram MD(Final)

NAME : DR.J.RAJARAM

COURSE : MD FINAL(ANESTHESIA)

CENTER : KILPAUK MEDICAL COLLEGE & HOSPITAL

GUIDE : DR.P.S.SHANMUGAM MD.DA PROF & HOD OF ANESTHESIA DEPT OF ANESTHESIA KILPAUK MEDICAL COLLEGE

INTRODUCTION Hypothesis of this study is to evaluate and

compare the effect of added dexmedetomidine to epidural ropivacaine 0.75%

40 patients under going elective lower limb orthopedic procedures under epidural were selected and divided into two groups of 20 each

Control group- epidural ropivacaine 0.75% 20ml (150mg)

Dex group- epidural ropivacaine 0.75% 20ml (150mg) + Dexmedetomidine 1μg/kg

METHODS

Ethical committee approval Informed consent Randomised double blind study 40 paients under going elective

orthopedic procedures were selected Absolute fasting of 8 hours , without

premedication

METHODS

ASA I & II BOTH SEXES AGE BETWEEN 18-70

yrs ELECTIVE ORTHOPEDIC

PROCEDURE UNDER EPIDURAL

ANESTHESIA WITHOUT COMORBID

ILLNESS

ALLERGY TO LOCAL ANESTHETICS

NM DISEASES USING α2

ANTAGONISTS WEIGHT MORE THAN

120 kg

INCLUSION CRITERIA EXCLUSION CRITERIA

CONTD.. I.V line secured for administration of

RL,10ml/kg/hr Monitors include pulse oximetry, NIBP,

ECG Epidural

Performed with 16G Tuohy needle Lumbar epidural space Sitting position Loss of resistance technique

GROUPS CONTROL GROUP(N=20) :

Epidural ropivacaine 0.75% 20ml(150mg)+1 ml NS

DXMEDETOMIDINE GROUP(N=20) : Epidural ropivacaine 0.75% 20ml(150mg)+

Dexmedetomidine 1μg/kg+NS to complete 1ml 20ml 0.75% injected at the rate of 1ml/3sec Patients were treated with titrated doses

ephedrine 6mg if systolic BP<90mmhg, with atropine 0.6mg if HR<60/min

Patients were sedated on demand basis

VARIABLES BLOCK ONSET TIME MAXIMUM DERMATOMAL LEVEL OF ANESTHESIA DURATION OF SENSORY AND MOTOR

BLOCKADE MOTOR BLOCK INTENSITY-BROMAGE MOTOR

SCALE SENSORY BLOCK-SENSORY SCALE LEVEL OF SEDATION-RAMSEY SEDATION SCALE HEMODYNAMICS DURATION POST OPERATIVE ANALGESIA-VAS

SCORE

DEFINITION OF VARIABLES SENSORY BLOCK ONSET TIME

Time interval between end of anesthetic injection and appearance of cutaneous analgesia in dermatomes T-12,T-10,T-8,T-6

DURATION OF MOTOR BLOCK Administration of anesthetic and attainment of grade 0 in

Bromage motor scale DURATION OF ANALGESIA

Administration of anesthetic and disappearance of cutaneous level at each dermatomal level

POST-OP ANALGESIA DURATION Administration of anesthetic and time of analgesic usage in

PACU SUPPLEMENTAL SEDATION

If patient felt pain or uncomfortable , with pentazocine 0.3mg/kg and or midazolam 0.02mg I.V

BROMAGE MOTOR SCALE

GRADE CRITERIA DEGREE OF BLOCK0 FREE MOVEMENT OF LEGS AND

FEETNIL(0%)

1 JUST ABLE TO FLEX KNEES WITH FREE MOVEMENT OF KNEES

PARTIAL(33%)

2 UNABLE TO FLEX KNEES,BUT WITH MOVEMNT OF FEET

ALMOST COMPLETE (66%)

3 UNABLE TO MOVE LEGS OR FEET COMPLETE (100%)

RAMSEY SEDATION SCALE

SENSORY SCORE

SCORE RESPONSE0 NORMAL SENSATION

1 ANALGESIA(LOSS OF PIN PRICK SENSATION)

2 ANESTHESIA(LOSS OF TOUCH)

STATISTICS

Variables were analyzed with Student ‘t’ test, Chi Square test

Variables like age, sex, weight, height were compared using Levene’s test for equality of variance

Sample size obtained according to previous background study

‘p’ value less than 0.05 was taken as significant

RESULTS One patient in control group was excluded for

failure of epidural block and need for GA Distributions of age, weight, height, sex and type of

surgery , duration of surgery between groups(p>0.05)

Block onset time T-12,T-10,T-8,T6 between groups-shortened onset time, with less significance(p<0.08)

Regression time is prolonged in dex group(p<0.01) Maximal level of analgesia assessed after 60mins

between groups were T-4 to T-6, without significance

Block Onset Time

Regression Time

Upper Level Of Analgesia

SEX DISTRIBUTION

DISTRIBUTION OF SURGERY

EPIDURAL CATHETER LENGTH

VARIABLES CONTROL DEXAge 42.25 39.10

SexFemale 3 4Male 17 16

Height (cm) 169.35 163.15Weight (kg) 69.95 66.75

Level Of EpiduralL1-L2 2 2L2-L3 10 10L3-L4 8 8

Cathetar Length (cm) 6.5 6.85

Surgery

IM / IL Nailing 10 9Illizarao ring fixation 4 2DHS 2 5TKR 1 1THR 1 0DCS 0 1Encirclage / TBW L Patella 1 0Plate & Screw fixation 0 2Hemiarthroplasty 1 0

ASAI 12 15II 8 5

DURATION OF SURGERY (mins) 158.25 177

CONTD.. Duration of analgesia-prolonged in Dex

group, level of significance-(p<0.05) Motor block duration-prolonged in Dex

group, level of significance(p<0.05) Intensity of motor block-increased intensity

in dex group,without significance(p<0.37) Supplemental sedation-reduced need in Dex

group , level of significance Patient given supplemental mask O2 if SpO2

<94% Duration of post-op analgesia-significantly

prolonged in Dex group, level of significance (p<0.01)

VARIABLES CONTROL DEX ‘P’ VALUE

Block Onset Time (T-12)mins 13.90 12.45 0.085

Duration Of Analgesia (mins) 236.35 304.25 0.021

Regression Time 115.55 177.30 0.051

Motor Block Duration (mins) 204.65 248.00 0.042

Post Of Analgesia (mins ) 309 496.95 0.001

Contd.. Need for vasopressors- similar between

groups with out much significance(p>0.13) Occurrence of hypotension with need for

vasopressor Occurrence of bradycardia and need for vagolytic

Hemodynamic stability-stable in both groups without much significance(p<0.06)

Occurrence of other complications like shivering, nausea , RS depression in intra and post-op period –similar between groups

Epidural catheter was used for giving rescue analgesia with 0.2% ropivacaine 10ml (20mg)

SEDATIVE USAGE

ROPIVACAINE

ROPIVACAINE It is a long acting amide local anesthetics Ropivacaine is ‘S’ isomer of the propyl analogue of

mepivacaine and bupivacaine Similar to bupivacaine ,but with better cadiotoxicity

profile, dissociates from Na+channels more rapidly Produces less accumulation of Na+channel block

Significantly better sensory-motor differentiation,due to lower lipid solubility than bupivacaine

Has mild intrinsic vasoconstricting properties unsuitable for infiltration in tissues without collateral blood

supply Reason for longer cutaneous anesthesia

PROPERTIES-ROPIVACAINE pKa is 8.07 Protein binding is 94% Partition co-efficient is 115 CC:CNS ratio is 5:1 Potency 4

DISCUSSION

According to result, There is a synergistic interaction of dex and

ropivacaine during epidural administration Addition of Dex prolongs analgesic and

motor blockade duration and post-op analgesia

Decreases the requirement of supplemental sedation

It does not affect onset time

DEXMEDETOMIDINE

DEXMEDETOMIDINE Dex is an agonist of α2 adrenergic receptor –

agonist where ratio among α2 : α1 is 1600:1 Dex epidural effect is dose dependent and

superior than I.V due to its high affinity for α2 adrenergic receptors in spinal cord

Dex first administered epidurally in 1997, combined with 1.5% lignocaine for patients undergoing hystrectomy

8 times greater selectivity than clonidine towards α2 adrenergic receptor

DEX.. After epidural administration of Dex , it is rapidly

detected in CSF within five mins,however only 22% is absorbed into intra thecal space Dex inhibition of locus caeruleus results in

disinhibition of of NA nuclei and exerts descending inhibitory effect on nociception in spical cord

Anti-nociceptive effect is Dose dependent Related to affinity of located α2 in spinal card Higher lipid solubility

Prolonged analgesic action of LA is due to Reduced systemic absorbtion caused by local

vasoconstriction mediated byα2C in smooth muscle of epidural venous plexus

DEX.. Sedative effect of Dex,

Mediated by binding to α2A receptors in locus caeruleus Diminishes release of norepinephrine During epidural administration cephalad spread into

meninges may be responsible for sedation Dex cause more sensory than motor block duration

4 times the dose is required for inhibition large ,myelinated Aα fibers when compared to small unmyelinated C fibers

Bradycardia Is dose dependent Occurs in epidural if level is higher

Shivering incidence may be reduced with α2 agonists due to central inhibition of thermoregulatory centre

CONCLUSION DEX has significant synergistic

interaction with epidural Ropivacaine in Prolonging duration of analgesia(p<0.02) Prolonging duration motor block(p<0.04) Post-op duration of analgesia(p<0.001)

Ref. brazilia scandinavia ,journal

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