ppt chapter 25

Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins

Muscle RelaxantsMuscle Relaxants

Chapter 25


Regulation of Movement and Control of Muscles

Regulation of Movement and Control of Muscles

• Spinal Reflexes

• Influences from Upper-level CNS Areas

– Basal ganglia

– Cerebellum

– Cerebral cortex


Types of Spinal ReflexesTypes of Spinal Reflexes

• Simple

– Involving an incoming sensory neuron and an outgoing motor neuron

• Complex

– Involving interneurons which communicate with the related centers in the brain


Reflex Arc Showing Pathway of ImpulsesReflex Arc Showing Pathway of Impulses


Fibers in the CNS Controlling Different Types of Movements

Fibers in the CNS Controlling Different Types of Movements

• Pyramidal Tract

– Controls precise intentional movements

• Extrapyramidal Tract

– Modulates unconsciously controlled muscle activity

– Allows the body to make automatic adjustments in posture, position, and balance


Neuromuscular AbnormalitiesNeuromuscular Abnormalities

• Muscle Spasm

– Often results from injury to the musculoskeletal system

– Caused by the flood of sensory impulses coming to the spinal cord from the injured area

• Muscle Spasticity

– Result of damage to neurons within the CNS

– May result from an increase in excitatory influences or a decrease in inhibitory influences within the CNS


Action of Skeletal Muscle RelaxantsAction of Skeletal Muscle Relaxants

• Most Relaxants

– Work in the brain and spinal cord

– Interfere with cycle of muscle spasm and pain

• Botulinum Toxins and Dantrolene

– Enter muscle fibers directly


Action of Centrally Acting Skeletal Muscle Relaxants

Action of Centrally Acting Skeletal Muscle Relaxants

• Work in the upper levels of the CNS to interfere with the reflexes causing the muscle spasm

– Possible depression anticipated with their use

• Lyse or Destroy Spasm

– Often referred to as spasmolytics


QuestionQuestion

Which of the following may result in muscle spasticity?

A. A decrease in inhibitions

B. An increase in excitatory influences

C. An increase in inhibitory influences

D. A decrease in excitatory influences


AnswerAnswer

B. An increase in excitatory influences

Rationale: Muscle spasticity may result from an increase in excitatory influences or a decrease in inhibitory influences within the CNS.


Centrally-Acting Skeletal Muscle Relaxants

Centrally-Acting Skeletal Muscle Relaxants

• Actions

– Exact mechanism of action is not known

– Thought to involve action in the upper or spinal interneurons

• Indications

– Alleviation of signs and symptoms of spasticity; use in spinal cord injuries or diseases

• Pharmacokinetics

– Rapidly absorbed and metabolized in the liver

– Excreted in the urine


Centrally-Acting Skeletal Muscle Relaxants (cont.)


• Contraindications

– Known allergy

– Rheumatic disorders

• Cautions

– Epilepsy

– Cardiac dysfunction

– Conditions marked by muscle weakness




• Adverse Reactions

– Drowsiness

– Fatigue

– Weakness

– Confusion

– Headache

– Nausea




• Adverse Reactions (cont.)

– Dry mouth

– Hypotension

• Drug-to-Drug Interactions

– CNS depressants


Direct-Acting Skeletal Muscle RelaxantsDirect-Acting Skeletal Muscle Relaxants

• Actions

– Interfering with the release of calcium from the muscle tubules

– This prevents the fibers from contracting

– Does not interfere with neuromuscular transmission

• Indications

– Treatment of spasticity directly affecting peripheral muscle contraction

– Management of spasticity associated with neuromuscular diseases


Direct-Acting Skeletal Muscle Relaxants (cont.)


• Pharmacokinetics

– Slowly absorbed from the GI tract

– Metabolized in the liver

– T ½ 4-8 hours

– Excreted in the urine

• Contraindications

– Known allergy

– Spasticity




• Contraindications (cont.)

– Hepatic disease

– Lactation

• Cautions

– Women

– All patients older than 35 years

– Cardiac disease




• Adverse Reactions

– Fatigue

– Weakness

– Confusion

– GI irritation

– Enuresis

• Drug-to-Drug Interactions

– Estrogen

– Neuromuscular junction blockers


Mechanisms of Muscle RelaxantsMechanisms of Muscle Relaxants


Use of Muscle Relaxants Across the Lifespan

Use of Muscle Relaxants Across the Lifespan


Prototype Centrally Acting Skeletal Muscle Relaxants

Prototype Centrally Acting Skeletal Muscle Relaxants


Prototype Direct-Acting Skeletal Muscle Relaxants

Prototype Direct-Acting Skeletal Muscle Relaxants


Nursing Considerations for Centrally-Acting Skeletal Muscle Relaxants

Nursing Considerations for Centrally-Acting Skeletal Muscle Relaxants

• Assessment: History and Physical Exam

• Nursing Diagnosis

• Implementation

• Evaluation


Nursing Considerations for Direct-Acting Skeletal Muscle Relaxants

Nursing Considerations for Direct-Acting Skeletal Muscle Relaxants

• Assessment: History and Physical Exam

• Nursing Diagnosis

• Implementation

• Evaluation


Question Question

A patient experienced a musculoskeletal injury resulting in a great deal of pain in his lower back. How can the nurse augment the drugs to aid in pain relief?

A. Moist cold

B. NSAIDs

C. Passive exercise

D. Active exercise


AnswerAnswer

B. NSAIDs

Rationale: Provide additional measures to relieve discomfort—heat, rest for the muscle, NSAIDs, positioning— to augment the effects of the drug at relieving the musculoskeletal discomfort.

ppt chapter 25

Documents

skeletal muscle relaxantscont

muscle weakness

muscle relaxantschapter

cycle of muscle spasm

controlled muscle activity

tothe spinal cord

gi tract

excitatory influencescopyright