Introduction:

Rapid sequence intubation(RSI) usually applies when tracheal intubation must be performed in a patient whom is suspected to have a full stomach and patient who is at high risk of pulmonary aspiration of gastric contents.The RSI goal is to secure the airway without producing any vomiting or regurgitation.The second objective involves minimization of induction-intubation interval, which means that a short acting hypnotic agent should be administered with a rapidly acting neuromuscular blocking agent.Vecuronium, is a cardiac stable, mono-quarternary, steroidal, non depolarizing muscle relaxant, competitive neuromuscular inhibitor which has been shown to provide adequate intubating conditions with slower onset of action(3 to 5minutes),intermediate duration(25 to 30mts) and no side effects.Priming is the administration of one tenth of the intubating dose of non depolarizing blocker few minutes before the full intubating dose.The concept of priming technique is that the initial 1/10^th of non depolarizing muscle relaxant occupies and blocks large number of acetylcholine receptors before apparent clinical reduction in neuromuscular transmission.Hence the 2^nd dose blocks the remaining receptor leading to rapid onset of intubation.Many studies have proved that this approach hastens the onset of non depolarising muscle relaxants.Magnesium potentiates neuromuscular blockade through inhibition of calcium mediated release of acetylcholine from pre-synaptic nerve terminals at the neuromuscular junction and also a decrease in post synaptic sensitivity to acetylcholine and direct effects on the membrane potential of myocytes, thus augmenting the effect of non depolarizing neuromuscular blockade.MgSo4 pre treatment should reduce the onset time of vecuronium induced block to an extent that makes it an alternative to succinylcholine for rapid sequence intubation.After pre treatment with Magnesium sulphate (MgSo4),an increased speed of onset and prolongation of the recovery period of neuromuscular end plate is both time dependent & concentration dependent in patients using Vecuronium for RSI. The study comparing Magnesium sulphate with vecuronium are very limited, hence in this study we are comparing the effect of priming dose of vecuronium with that of MgSo4 on the onset time of intubation in patients undergoing surgeries under General anaesthesia

AIM & OBJECTIVES: 

Aim:

Our study is to compare the effect of priming dose of Vecuronium with that of Magnesium sulphate on the onset time of intubation in patients undergoing surgeries under General Anaesthesia

Objectives:

Primary Objective:

Ø To compare the onset of time of intubation among the 3 groups

Secondary Objective:

Ø To compare the duration of vecuronium in all 3 groups

Ø To look for ease of intubation

Ø To observe haemodynamic response in all groups

Ø To look for any side effects like muscle weakness,oliguria,ptosis,difficulty in swallowing,breathing difficulty.

Review Of Literature: 

1.    Nalini KB et al.,^[1] conducted a randomized trial of pretreatment of magnesium sulphate accelerates neuromuscular block as compared to vecuronium priming using 120 patients, which has 3 groups- 40 each.  Group-N: They were randomly allocated to control, received 100mcg/kg vecuronium after saline infusion.  Group-P: vecuronium priming, received 10 mcg/kg vecuronium followed by 90 mcg/kg vecuronium.  Group-M: Magnesium group, patients were infused with 40 mg/kg magnesium sulphate followed by 100 mcg/kg vecuronium.  This study conclude that pretreatment of magnesium infusion accelerates the onset of action of neuromuscular blockers and prolongs their duration of action.

2.    Vimala et al.,^[2] conducted a study on Rapid sequence intubation using vecuronium in 70 patients, which has seven groups of ten patients each were studied. One group, the “standard” group, was given succinylcholine, 1.5 mg/kg, for tracheal intubation.  The remaining six groups received vecuronium according to the dose. This study concludes Intubating conditions were not satisfactory within 60 sec when a single large dose (150 mcg/kg) of vecuronium was used. Only six of ten patients could be intubated in 60 sec. When a priming dose of vecuronium was used 5 min before the total dose, all the patients could be intubated in 60 sec. Only five of the ten patients given 7 mcg/kg priming.

3.    T. Fuchs-Buder et al.,^[3] studied about Interaction of magnesium sulphate with vecuronium induced neuromuscular block in 125 patients.  Part-1 (60 patients) for dose response.  Group-A: 30 patients - received MgSO4 40 mg/kg  in saline as an i.v. infusion over 15 min.  Group-B: 30 patients received the same volume of saline without MgSO4.  This study concluded that the neuromuscular potency of vecuronium was increased markedly by MgSO4.

4.    Tassonyi et al.,^[4]  conducted a study on Magnesium sulphate enhances residual neuromuscular block induced by vecuronium in 30 patients.  2 groups: 15 each.  Group A: iv MgSo4 60mg/kg given 1 min before giving rocuronium 0.6mg/kg.  Group B: iv normal saline given 1 min before giving rocuronium 0.6mg/kg.  This study concluded that prior administration of magnesium sulphate, prolonged rocuronium-induced neuromuscular block but did not increase speed of onset.

5.    Okuda et al.,^[5] conducted a study on pretreatment with magnesium sulphate enhances vecuronium-induced neuromuscular block.  This study has 2 groups.  Group-A: iv MgSO4 (20 or 40 mg/kg) with vecuronium.  Group-B: iv normal saline with vecuronium.  He concluded that the neuromuscular effect of vecuronium was not influenced by pretreatment with MgSO4 20 mg. On the contrary, the onset time of vecuronium was decreased and the duration of action until 25% recovery was increased by pretreatment with MgSO4 40 mg.

JUSTIFICATION:

v At a priming dose of 0.01mg/kg, the onset time of intubation with vecuronium is same as that of succinyl choline (60 seconds)

v There are no significant studies done comparing the priming effect of Vecuronium with that of MgSo4 on the onset time of intubation

METHODS:

v Study Population:

            Study population consists of ASA 1,2,3 patients scheduled for elective surgery under General Anaesthesia

v Study Design:

            This study will be designed as a prospective, randomized, single blinded, controlled study

SAMPLE SIZE:

Sample size suggested for the present study is 20 in each group

v Each group has 20 patients

Ø Group 1: n=20                    

            Patients will receive 0.01mg/kg of vecuronium 4 minutes prior to loading dose of 0.09 mg/kg

Ø Group2: n=20

              Patients will receive 50 mg/kg of magnesium sulphate 10 mins prior to loading dose of 0.1 mg/kg of vecuronium

Ø Group3: n=20

             Infusion of 100ml normal saline will be given over 10 mins prior to induction with 0.1 mg/kg of vecuronium, will be considered as the control group.

MATERIALS & METHODS:

•        Study type: Interventional

•        Study design: Prospective, Randomised, Single blinded study

•        Study population: After obtaining Ethical Committee approval and CTRI registration, 60 patients who will undergo elective surgeries at Chettinad Hospital and Research Institute, Kelambakkam, Chengelpet, will be taken up for study.

•        Inclusion Criteria:

Ø American Society of Anaesthesiologists (ASA) 1,2,3

Ø Age group between 18 to 60 years of both sexes

Ø Patients posted scheduled for elective surgeries under General anaesthesia

Ø Mallampatti Grade 1,2,3

Ø BMI < 30

•        Exclusion Criteria:

Ø Patient refusal

Ø Anticipated difficult intubation

Ø BMI > 30

Ø If patient allergic to study drugs

Ø Emergency surgeries

Ø Pregnant patients

Ø Patients with significant hepatic,renal,metabolic,neuro muscular disorder

METHODOLOGY:

v After obtaining approval by the Institutional Human Ethics Committee and CTRI registration, and written informed patient consent, 60 patients under ASA physical status I,II,III patients scheduled for elective surgeries, will be included in a prospective, randomized, single-blinded clinical trial at Chettinad Hospital and Research Institute, Kelambakkam, Chennai.

v Patients with anticipated difficult airway, risk of aspiration, renal or cardiac disease will excluded from this study

v In the preoperative assessment, detailed history and physical examination, baseline data like pulse rate, blood pressure, SpO2 and basic investigations will be collected.

v Informed and written consent will be obtained

v All patients were kept by Nil Per Oral for about 8 hours prior to surgery and will be premedicated with Tab.Alprazolam0.5mg & Tab.Ranitidine150mg will be given the previous night of surgery & morning of surgery

v IV access will be secured for all patients with 18G iv cannula

v On arrival to operation theatre, standard monitoring of pulse oximetry, Non invasive blood pressure (NIBP), continuous electrocardiogram (ECG) will be established and baseline variable values will be noted before the procedure.

v TOF watch will be connected in the wrist to look for adductor pollicis action.

v Patient will receive Inj.Midazolam1mg iv 15minutes prior to induction

v The study drug will be given as per the selected time period (Either 4minutes or 10minutes)

v After 3minutes of Pre oxygenation with 100% O2

v Anaesthesia will be induced with fentanyl2mcg/kg, propofol2mg/kg

v The response of the 1^st dorsal interosseous muscle of hand to supramaximal Train Of Four (TOF) stimulation of ulnar nerve at the wrist at 20sec intervals measured electromyographically

v Remaining dose of vecuronium 0.1mg/kg as neuromuscular agent will be given

v Speed of onset will be determined with TOF (Train Of Four)

v After the TOF becomes zero, a Senior anaesthesiologist will perform the intubation

v Another anaesthesist will assess the onset time, intubating conditions and clinical duration of neuromuscular block in different groups.

v The onset time of intubation will be noted.Onset time is defined as the time from the injection of the intubating dose of muscle relaxant to the time when all 4 twitches disappeared.Is recorded in seconds

v The duration of muscle relaxation is also monitored.Duration time is defined as the time from the injection of intubating dose of muscle relaxant to the time when the first twitch reappeared.Is recorded in minutes.

v Anaesthesia will be maintained with Isoflurane 1-2% in Oxygen and Nitrous oxide.Maintainance dose of vecuronium of 0.01 to 0.015 mg/kg will be required every 30 to 40 minutes

v Ease of intubation will be graded with Cooper scoring system

v  Haemodynamic changes will be monitered and noted till the end of surgery.

Cooper Scoring System:

§  8-9 Excellent

§  6-7 Good

§  3-5 Fair

§  0-2 Poor

REFERENCE:

1.    Pretreatment of magnesium sulphate accelerates neuromuscular block as compared to vecuronium priming – A randomized trial Nalini KB1,*, Muralidhar Danappa Patel2 , Pandya Khushal3

2.    Rapid sequence intubation using vecuronium - Vimala E.Kunjappan MD,Eli M.Brown MD and Gaylord D.Alexander MD

3.    Interaction of magnesium sulphate with vecuronium induced neuromuscular block - T. FUCHS-BUDER, O. H. G. WILDER-SMITH, A. BORGEAT AND E. TASSONYI

4.    Magnesium sulphate enhances residual neuromuscular block induced by vecuronium T. FUCHS-BUDER AND E. TASSONYI

5.    Pretreatment with magnesium sulphate enhances vecuronium-induced neuromuscular block. Okuda T ¹, Umeda T, Takemura M, Shiokawa Y,KogaY