Small Doses Muscle Relaxant in General Anesthesia

Study Overview
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Brief Summary
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This study will be held to assess the effect of minimal dose muscle relaxant on postoperative pulmonary function. The time to extubation in minutes will be the primary outcome as a clinical indicator of the return of muscle power. The extubation time will be defined as the time from injecting the muscle relaxant reversing agent given when regain the train of four (TOF) ratio to 0.9 till removal of endotracheal tube. Intraoperative surgical conditions will be assessed in the form of surgeon satisfaction and the need for more muscle relaxant boluses. Postoperative complications as desaturation (peripheral oxygen saturation (Spo2) less than 90%), the need for re-intubation or ventilation support will be recorded. Patient lung will be assessed using ultrasound-based lung aeration score. Also, the diaphragmatic and intercostal muscle function will be assessed in the early postoperative period. Immediate postoperative pulmonary function tests will be evaluated using simple spirometer. Patients will be followed up for 28 days for detection of pulmonary complications.

Detailed Description
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After arrival to the operating theater, a thoracic US examination will be done using LUS dynamic re-aeration score. Patients will be randomly allocated via sealed opaque envelopes into 2 groups of 30 patients each; control (C) group and minimal dose (Min) group. For general anesthesia; intubating dose of muscle relaxant will be injected according to the study group; in C group; atracurium 0.5 mg/kg while in min group 0.2 mg/kg will be injected. The trial for intubation will be assessed and recorded. Train-of-four (TOF) stimulation will be maintained less than 2 throughout the intraoperative period in the control group. While, in the min group, boluses of muscle relaxant will be given only upon complain of the surgeon and after a bolus dose of propofol 0.5 mg/kg. When required, 20% of the initial dose of muscle relaxant will be provided as a bolus to achieve this goal.

Official Title
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Respiratory Benefits of Small Doses Muscle Relaxant in General Anesthesia

Conditions
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Muscle Relaxant

Intervention / Treatment
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* Drug: Atracurium Besylate regular dose
* Drug: Atracurium Besylate minial dose


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: adult patients aged from 20 to 50 years old scheduled for non-cardiothoracic surgery under general anesthesia in supine position after informed consent Exclusion Criteria: American Society of Anesthesiologists (ASA) score more than 3 suspected full stomach or who will undergo intervention expected to necessitate profound muscle relaxation or dressing interferes with ultrasound (US) probe positioning Lung parenchymatous disease renal disease hepatic disease neuromuscular disease electrolytes imbalanc on medication interfere with muscle contraction with known allergy to any drug used in the study

Ages Eligible for Study
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Minimum Age: 20 Years
Maximum Age: 50 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Treatment
Allocation: Randomized
Intervention Model: Parallel Assignment
Interventional Model Description: Patients will be randomly allocated via sealed opaque envelopes into 2 groups of 30 patients each; control (C) group and minimal dose (M) group
Masking: Double


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Active Comparator: control (C) group<br>Intubating dose of muscle relaxant will be atracurium 0.5 mg/kg Maintenance doses of muscle relaxant will be given throughout the intraoperative period to maintain the Train-of-four values continuously less than 2 | Drug: Atracurium Besylate regular dose<br>* Intubating dose of muscle relaxant will be atracurium 0.5 mg/kg Maintenance doses of muscle relaxant will be given throughout the intraoperative period to maintain the Train-of-four values continuously less than 2<br>|
| Experimental: minimal dose (M) group<br>Intubating dose of muscle relaxant will be 0.2 mg/kg will be injected boluses of muscle relaxant will be given only upon complain of the surgeon and after a bolus dose of propofol 0.5 mg/kg. When required, 20% of the initial dose of muscle relaxant will be provided as a bolus to achieve this goal. | Drug: Atracurium Besylate minial dose<br>* atracurium boluses of muscle relaxant given only upon complain of the surgeon and after a bolus dose of propofol 0.5 mg/kg. When required, 20% of the initial dose of muscle relaxant will be provided as a bolus to achieve this goal<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| The time to extubation in minutes | the time from injecting the muscle relaxant reversing agent given when regain the train of four (TOF) ratio to 0.9 till removal of endotracheal tube | after injecting the muscle relaxant till removal of the tracheal tube | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Time to the first intraoperative need of muscle relaxant bolus (Atracurium), in the M group | blouse of muscle relaxant given only upon complain of the surgeon and after a bolus dose of propofol 0.5 mg/kg | Given intraoperatively only upon complain of the surgeon and after a bolus dose of propofol 0.5 mg/kg | 
| Total doses of propofol used in M group post-induction | a bolus dose of propofol 0.5 mg/kg given in the M group, upon complain of the surgeon and before boluses of muscle relaxant | intraoperatively | 
| first Postoperative day complications | desaturation (Spo2 less than 90%), need for re-intubation, need of ventilation support | after removal of the tracheal tube and for 24 hours postoperative | 
| lung aeration via Lung ultrasound dynamic re-aeration score | 0= normal aeration (horizontal A-lines or ≤ 2 B-lines); 1 = moderate loss of aeration (multiple B-lines, either regularly spaced (7 mm apart), or irregularly spaced and even coalescent but only visible in a limited area of the intercostal space); 2 = loss of aeration (multiple coalescent B-lines, in prevalent areas of the intercostal spaces and observed in one or several intercostal spaces); 3 = complete loss of aeration (lung consolidation, with or without air bronchograms) | basal immmediate preoperative & with first 30 minutes postoperative |