Magnesium sulphate as an adjuvant to intrathecal

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Transcript Magnesium sulphate as an adjuvant to intrathecal

 Dr.K.VENKATESAN MD II YEAR

PROF&HOD.DR.P.S.SHANMUGAM MD,DA.

DEPARTMENT OF ANESTHESIA KILPAUK MEDICAL COLLEGE & HOSPITAL CHENNAI

 To study and compare the effect of added fentanyl 25(mic gm) & Mgso4 0.1cc 50%(50mg) to 0.5% 2cc(10mg)bupivacaine in spinal anesthesia  Patients undergoing elective LSCS  With mild gestational hypertension(PIH)

 Adequate analgesia following caesarian section decreases morbidity , improves patient ambulation &outcomes ,facilitate care of the new born.

 Intrathecal MgSO4 , NMDA antagonist has been shown to prolong analgesia without significant side effects in healthy parturients  Correlation was found between serum & CSF Mg concentration in patients with preeclampsia

 Ethical committee approval  Informed patient consent  Randomised double blind controlled study  Statistical significance is ‘p’ value less than 0.05

 SAB performed   With pt in right lateral position 25G quincke needle

 60 patient ASA risk I &II undergoing elective caesarian section with mild PIH .

 IV line secured with 18G venflon, and preloaded with RL 10-12ml /kg  All pts received 5L of O2 / min through face mask throughout procedure  Pts treated with titrated doses of   Inj.ephedrine 6mgI.V if BP<90mmhg Inj.Atropine 0.6mg if HR<60/min  After delivery of baby Inj. Syntocin 10 IU in drip and 10 IU IM given

 Mild PIH is defined as SBP 140 – 160 and DBP 90 – 110mm Hg with or without proteinuria after 20 wk. gestation  60 pts with average age of 18 – 35 undergoing elective LSCS under SA were randomized into three groups of 20 each  Minimal fasting period is 8hrs  All pts received premedication with Inj. Ranitidine 50mg IV and Inj. Metoclopramide 10 mg IV, 15 min before surgery

 Age between 18-35 years  Elective LSCS  under spinal anesthesia  Mild PIH (BP<160/110mmhg)  ASA I/II

INCLUSION

 Contraindication to regional anesthesia  Heart disease  Fetal distress  Seizure disorder  Severe eclampsia  Pts with coagulation defect  Allergy to LA

EXCLUSION

 Group C:  control group,(N=20) patients 0.5% 2cc(10mg)bupivacaine + 0.6cc normal saline .

 Group F:  Fentanyl(N= 20) patients received 0.5% 2cc bupivacaine +0.5cc( 25mic gm )fentanyl +0.1cc NS.

 Group M:  Mgso4 group (N=20),0.5% 2cc bupivacaine +0.5cc fentanyl +0.1cc 50%(50mg) Mgso4 .

 Variables were analysed by ANOVA  Variables analysed and interperted by post Hoc test  Statistical significance is ‘p’ <0.05

 NIBP  PULSEOXIMETER  ECG  RESPIRATORY RATE  URINE OUTPUT

GRADE

0 1 2 3

RESPONSE

NO MOTOR BLOCK UNABLE TO STRAIGHT LEG RAISE UNABLE TO FLEX KNEE AGAINST RESISTANCE UNABLE TO FLEX ANKLE

DEGREE OF BLOCK

NIL(0%) PARTIAL(33%) ALMOST COMPLETE(66%) COMPLETE

4 5 6

SCORE

1 2 3

RESPONSE

ANXIOUS OR RESTLESS OR BOTH COPERATIVE, ORIENTED & TRANQUIL RESPONDS TO COMMANDS BRISK RESPONSE TO STIMULUS SLUGGISH RESPONSE TO STIMULUS NO RESPONSE TO STIMULUS

SCORE RESPONSE

0 1 2 NORMAL SENSATION ANALGESIA (LOSS OF PIN PRICK SENSATION) ANAESTHESIA (LOSS OF TOUCH SENSATION)

 Block onset time  Duration of sensory blockade  Higher level of sensory block  Time to reach highest block  Two segment regression time  Duration of postop analgesia  Hemodynamic parameters

 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 of sensation at each dermatomal level  POST-OP ANALGESIA DURATION  Administration of anesthetic and time of analgesic requirement in PACU

      The onset of both sensory and motor block was delayed in the group M ,when compared to both C&F group(p<0.001) Motor block and analgesic duration was prolonged in the Group M , level of significance (p<0.05) Two segment regression time increased in M group (P<0.001) Group M is hemodynamicaly stable when compared to other groups (p<0.019) Attainment highest level sensory block varies from T1-T6 , delayed in group M with significance level (p<0.08) Intensity of motor block is more with group M, but with less significance (p<0.291)

      Occurrence of other complications like Bradycardia , nausea ,shivering were comparable in all groups Two Patient in group F complained of itching Usage of vasopressors is more in group C when compared to other groups Fetal outcome assessed by first min and fifth min APGAR was similar between groups (p>0.3) Height and weight are similar between groups(p<0.586) Investigations were similar between groups (p<0.32)

 Duration of post-op analgesia is prolonged in M group when compared to other groups (p<0.001)  Use of vasopressors is reduced in group M(p<0.03)

SENSORY BLOCK ONSET TIME F M C

F M C

F M C

ANALGESIC & MOTOR BLOCK DURATION F M C

MOTOR BLOCK ONSET TIME F M C

POST-OP ANALGESIA DURATION F M C

 Magnesium is the second most abundant intracellular cation  Involved in the regulation of many ion channels and enzymatic reaction  Has application in anesthesia because of its action as a non competitive NMDA receptor antagonist with anti-nociceptive effect

 Mgso4 has been shown to have anti nociceptive effects , because of its antagonistic action on the NMDA receptor  Passage of magnesium across BBB is limited  It can potentiate opioid analgesia by both central and peripheral mechanism  MgSO4 causes 1.vasodilation by ca2+ block 2.analgesic effect 3.inhibition of catecholamine release

 Mg inhibit calcium entry into the cell via a non-competitive NMDA receptor blockade  Mg is also a physiological calcium antagonist at different voltage gated calcium channel, it may be important for anti-nociception  Mg decreases incidence of post operative shivering  Response to NMDA receptor is greatly enhanced when ECF Mg concentration below physiological level.

 Decrease in pain intensity is not due to direct analgesic effect of Mg  But due to prevention of subsequent NMDA activation  Baseline CSF Mg level in pt with preeclamsia differ from normal patients which suggest base line alteration in BBB  Normal CSF Mg level was 2.2meq+/- 0.9, plasma 1.6Meq, CSF:plasma ratio 1.39

 Mg is neuroprotective in ischemic as well as excitotoxic brain injury

 Mg may dilate cerebral blood vessel and thus responsible for relieving vasospasm in pt with preeclampsia   Clinical relevant dose of Mg has no significant effect on V MCA, autoregulation and cerebral reactivity CO 2 Mg produce central desensitisation  Mg can potentiate NM junction  Spinal NMDA receptor antagonist is the reason for potentiation of LA and prolongation of post operative analgesia

 It is a synthetic opioids  Phenylpiperidine derivatives  Directly inhibit the NMDA receptor  Action of opioids in the bulbospinal pathways are critical for analgesic efficacy  Distribution of opioids receptors in descending pain control circuits indicates substantial overlap between µ & Κ receptors  µ receptors produce analgesia within descending pain control circuits.

 In parturients with mild PIH undergoing LSCS the addition of Mgso4 50mg to the intrathecal combination of bupivacaine & fentanyl     prolongs the duration of analgesia Prolongs motor block duration Delayed onset of sensory block Prolongs post op analgesia  Ref.pubmed,intl.journal of obstetric anesthesia ,SOAP.

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