Dr.K.VENKATESAN MD II YEAR SYNERGISTIC EFFECT OF MAGNESIUM SULPHATE AND FENTANY ADDED TO INTRATHECAL BUPIVACAINE FOR MILD PREECLAMSIA
GUIDE PROF&HOD.DR.P.S.SHANMUGAM MD,DA. DEPARTMENT OF ANESTHESIA KILPAUK MEDICAL COLLEGE & HOSPITAL CHENNAI
aim of the study • 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)
background • 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
METHODS • 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
Patient selection • 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
METHODOLOGY • 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
criteria • Age between 18-35 years • Elective LSCS • under spinal anesthesia • Mild PIH (BP<160/110mmhg) • ASA I/II • Contraindication to regional anesthesia • Heart disease • Fetal distress • Seizure disorder • Severe eclampsia • Pts with coagulation defect • Allergy to LA INCLUSION EXCLUSION
groups • 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 .
STATISTICS • Variables were analysed by ANOVA • Variables analysed and interperted by post Hoc test • Statistical significance is ‘p’ <0.05
INTRA OP MONITORING • NIBP • PULSEOXIMETER • ECG • RESPIRATORY RATE • URINE OUTPUT
Parameters observed • 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
attributes • 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
results • 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)
Contd… • 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)
Contd.. • 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 C F M
F M C
F M C
MOTOR BLOCK ONSET TIME F M C
MagNESIUMsulPHATE • 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
MagNESIUMsulPHATE • 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
Cont.. • 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.
Cont… • 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
Cont… • 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 CO2 • 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
FENTANYL • 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.
CONCLUSION • 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.