Skeletal Muscle Relaxants (Neuromuscular Blocking Agents)
Chapter 18Skeletal Muscle Relaxants(Neuromuscular Blocking Agents)Mosby items and derived items 2008, 2002 by Mosby, Inc., an affiliate of Elsevier Inc.
Uses of Neuromuscular BlockingAgents Facilitate intubationSurgeryEnhance ventilator synchronyReduce intracranial pressure (ICP)Reduce O2 consumptionTerminate status epilepticus and tetanusFacilitate procedures and studiesKeep patients immobileMosby items and derived items 2008, 2002 by Mosby, Inc., an affiliate of Elsevier Inc.
Physiology of the NeuromuscularJunction CNS BrainSpinal cordPNS Somatic motor nervous system (skeletal) Voluntary controlAutonomic nervous system Involuntary controlMosby items and derived items 2008, 2002 by Mosby, Inc., an affiliate of Elsevier Inc.
Physiology of the NeuromuscularJunction (cont’d) Neuron Cell bodyAxonsDendritesNeurotransmitter AcetylcholineAcetylcholinesterase (AChE)Mosby items and derived items 2008, 2002 by Mosby, Inc., an affiliate of Elsevier Inc.
Physiology of the NeuromuscularJunction (cont’d) Depolarization Action potential occursRepolarization Membrane potential returns to baselineMosby items and derived items 2008, 2002 by Mosby, Inc., an affiliate of Elsevier Inc.
Physiology of the NeuromuscularJunction (cont’d) Two ways to block muscle contraction Competitive inhibition Nondepolarizing agentsProlonged occupation and persistent binding Depolarizing agentsMosby items and derived items 2008, 2002 by Mosby, Inc., an affiliate of Elsevier Inc.
Nondepolarizing Agents Block acetylcholine receptors withoutactivating themMode of action Affect postsynaptic cholinergic receptors Compete against endogenous acetylcholine Effect is dose related Acetylcholinesterase inhibitors (neostigmine) canreverse blockadeMosby items and derived items 2008, 2002 by Mosby, Inc., an affiliate of Elsevier Inc.
Nondepolarizing Agents (cont’d) Pharmacokinetics of nondepolarizing agents Chemically resemble acetylcholineOnset of paralysis and duration of action varywidely and are dose dependentDuration can be increased by Advanced age Hepatic or renal failureMosby items and derived items 2008, 2002 by Mosby, Inc., an affiliate of Elsevier Inc.
Nondepolarizing Agents (cont’d) Metabolism When normal conduction returns, 75% ofreceptors may still be occupied by blocker Additional boluses may appear more potentd-Tubocurarine and doxacurium Minimally metabolizedPancuronium Hepatic metabolismMosby items and derived items 2008, 2002 by Mosby, Inc., an affiliate of Elsevier Inc.
Nondepolarizing Agents (cont’d) Metabolism (cont’d) Atracurium and cisatracurium Spontaneous degradation by pH and temperatureVecuronium Hepatic metabolismMivacurium Shortest acting (10 to 20 minutes) Eliminated by plasma cholinesteraseMosby items and derived items 2008, 2002 by Mosby, Inc., an affiliate of Elsevier Inc.
Nondepolarizing Agents (cont’d) Adverse effects and hazards Cardiovascular effects Vagolytic effectHistamine release Cause histamine release from mast cellsInadequate ventilation Paralysis of diaphragm and intercostalsMosby items and derived items 2008, 2002 by Mosby, Inc., an affiliate of Elsevier Inc.
Nondepolarizing Agents (cont’d) Reversal of nondepolarizing blockade Produced by cholinesterase inhibitorsInhibits cholinesterase that breaks downacetylcholineAllows more acetylcholine at junction to displaceblockerAgents Neostigmine Edrophonium PyridostigmineMosby items and derived items 2008, 2002 by Mosby, Inc., an affiliate of Elsevier Inc.
Depolarizing Agents Mode of action Depolarizes muscle membrane like acetylcholine Resistant to AchE for longer period Causes fasciculationsPhase I block Prolonged depolarization/flaccid paralysisPhase II block Resembles nondepolarizing block Limits use in repeat dosesMosby items and derived items 2008, 2002 by Mosby, Inc., an affiliate of Elsevier Inc.
Depolarizing Agents (cont’d) Metabolism Rapid hydrolysis by plasma cholinesteraseReversal No agents available for reversal of succinylcholineMosby items and derived items 2008, 2002 by Mosby, Inc., an affiliate of Elsevier Inc.
Depolarizing Agents (cont’d) Adverse effects and hazards Sympathomimetic response Vagal response with repeat boluses Muscle pain/soreness Hyperkalemia Increased intracranial, intraoptic, and intragastricpressure Malignant hyperthermiaMosby items and derived items 2008, 2002 by Mosby, Inc., an affiliate of Elsevier Inc.
Neuromuscular Blocking Agents andMechanical Ventilation Used to improve ventilation and oxygenation and toreduce pressureBeneficial in: Status asthmaticusInverse ratio ventilation and high-frequency oscillatoryventilation (HFOV)Status epilepticusNeuromuscular toxinsTetanusAcute respiratory distress syndrome (ARDS)Mosby items and derived items 2008, 2002 by Mosby, Inc., an affiliate of Elsevier Inc.
Neuromuscular Blocking Agents andMechanical Ventilation (cont’d) Precautions and risks Proper eye care Suctioning Proper sedation and analgesia Aspiration/nosocomial pneumonia Risk of prolonged skeletal muscle weakness Decubitus ulcers Deep venous thrombosis (DVT)Mosby items and derived items 2008, 2002 by Mosby, Inc., an affiliate of Elsevier Inc.
Neuromuscular Blocking Agents andMechanical Ventilation (cont’d) Use of sedation and analgesia Absolutely essential!Monitor for tachycardia, hypertension, diaphoresis, andlacrimationAnalgesics Fentanyl MorphineAmnestic sedatives Propofol Lorazepam MidazolamMosby items and derived items 2008, 2002 by Mosby, Inc., an affiliate of Elsevier Inc.
Neuromuscular Blocking Agents andMechanical Ventilation (cont’d) Interactions with neuromuscular blocking agents Inhaled anesthetics potentiate blockadeAminoglycosides also produce NMBAgents antagonizing NMB Phenytoin Azathioprine TheophyllinePotentiate blockade Acidosis Hypokalemia Hyponatremia Hypocalcemia HypomagnesemiaMosby items and derived items 2008, 2002 by Mosby, Inc., an affiliate of Elsevier Inc.
Neuromuscular Blocking Agents andMechanical Ventilation (cont’d) Choice of agents Situation dependentFactors Duration of procedure Need for quick intubation Adverse effects Route of elimination Drug interactions CostMosby items and derived items 2008, 2002 by Mosby, Inc., an affiliate of Elsevier Inc.
Monitoring of NeuromuscularBlockade Paralysis may mask clinical signs/symptomsMethods Visual Tactile ElectronicMosby items and derived items 2008, 2002 by Mosby, Inc., an affiliate of Elsevier Inc.
Monitoring of NeuromuscularBlockade (cont’d) Loss of muscle activity ragmReturn of muscle activity Occurs in reverse orderMosby items and derived items 2008, 2002 by Mosby, Inc., an affiliate of Elsevier Inc.
Monitoring of NeuromuscularBlockade (cont’d) Twitch monitoringTrain-of-four evaluation 2 Hz over 2 seconds 0 twitches 100% blockade 1 twitch 95% blockade 2 twitches 90% blockade 3 twitches 80% blockade 4 twitches 75% blockadeMosby items and derived items 2008, 2002 by Mosby, Inc., an affiliate of Elsevier Inc.
The Future of NeuromuscularBlocking Agents and Reversal Gantacurium NondepolarizingRapid onsetShort-actingOrgan-independent inactivationLess histamine releaseSugammadex Inactivates and removes NMBAReverses rocuronium and vecuroniumLess effective on pancuronium, succinylcholine, andbenzylisoquinoliniumsMosby items and derived items 2008, 2002 by Mosby, Inc., an affiliate of Elsevier Inc.
Neuromuscular Blocking Agents and Mechanical Ventilation Used to improve ventilation and oxygenation and to reduce pressure Beneficial in: Status asthmaticus Inverse ratio ventilation and high-frequency oscillatory ventilation (HFOV) Status epilepticus Neuromuscular
Neuromuscular Blocking Agents Depolarizing muscle relaxants and Nondepolarizing muscle relaxants 12. . 6- patient have risk of a hyperkalemic response to succinylcolin .examples 7-lack of resuscitative equipment 30. induced . neuromuscular recovery in a hypoventilating postoperative patient .
There are three types of muscle tissue: Skeletal muscle—Skeletal muscle tissue moves the body by pulling on bones of the skeleton. Cardiac muscle—Cardiac muscle tissue pushes blood through the arteries and veins of the circulatory system. Smooth muscle—Smooth muscle tis
then discuss the role that calpains play in skeletal muscle remod-eling in response to both exercise training and in response to pro-longed periods of skeletal muscle inactivity. Finally, we will also highlight the emerging evidence that calpains play an important signaling role in skeletal muscle. Calpains in Skeletal Muscle
Dr Anjali Saxena Page 1 SKELETAL MUSCLE- NOTES I Learning Objectives By the end of this section, you will be able to: Describe the layers of connective tissues packaging skeletal muscle Explain how muscles work with tendons to move the body Identify areas of the skeletal muscle fibers Describe excitation-contraction coupling & Neuromuscular junction
of skeletal muscle organization, gross to microscopic, that we describe in the following sections. Gross Anatomy of a Skeletal Muscle Each skeletal muscle is a discrete organ, made up of several kinds of tissues. Skeletal muscle "bers predominate, but blood vessels, nerve "bers, and su
Neuromuscular blocking agents or muscle relaxants enable anaesthetists to relax skeletal muscles therefore improving anaesthetic management, increasing safety and quality of tracheal intubation, and to provide favourab
the neuromuscular function. Muscle strength is reduced during hypothermia, both in the presence and in the absence of neuromuscular blocking drugs. A 2ºC reduction in body temperature may double the duration of neuromuscular blockade. A reduction in muscle strength must be expect
asset management system is fed to the operational systems and the help desk system, if appropriate. In this scenario, when the deployment team deploys a new piece of gear, whether a PC on a desk or a server in a rack in the machine room, they will take any necessary steps to update the asset management system (much of the task can be updated). Once that happens the asset should immediately .
