General and regional anaesthesia.pptx

Basics of general, regional and local anesthesia

1. Enumerate the Principles of Local, Regional and General Anesthesia Batch 2019 Dr. Ankita Singh Assistant Professor Department of Surgery

2. Learning objectives History Types & Meaning of Regional & General anaesthesia Principles Agents Advantage and disadvantages

3. History First successful demonstration of anaesthesia William Morton (1846)- Ether Other incidents use of Nitrous oxide Chloroform

4. Types of anaesthesia General anaesthesia (GA) Amnesia, Analgesia, Muscle relaxation Regional anaesthesia Provide: Anaesthesia & Analgesia Sole agent Adjunct to GA Techniques Topical Local infiltration Regional nerve blocks Central neuroaxial blocks

5. Key principles of anaesthesia Multidisciplinary collaboration

6. Principles of General anaesthesia Reversible state of unconsciousness 4 components: Amnesia Analgesia Inhibition of noxious reflexes Skeletal muscle relaxation Achieved by combination of IV anesthetics & analgesics Inhalational anesthetics, and Frequently muscle relaxants

7. Principles of General anaesthesia.. 3 Phases: Induction Maintenance- inhalational or intravenous infusion Reversal Indications: Major intra-abdominal and thoracic procedures Most neurosurgical operations Any procedure in which airway protection and mechanical ventilation are required

8. Principles of General anaesthesia.. The drugs used cause both desirable & undesirable effects Thus pharmacological effects must be matched to pathophysiology of patient’s comorbidities Major adverse changes Respiratory depression Cardiovascular depression Loss of airway maintenance and protection Important complications: Hypoxemia, hypotension, cardiac arrest, aspiration of gastric contents

9. Principles of Regional anaesthesia First produced with cocaine (1800s) Temporary block nerve by injecting LA agent Includes: Central Neuraxial blocks: Spinal Epidural Caudal Peripheral Nerve blocks Truncal: Abdominal wall B (TAP, Rectus,Ii-Ih , Ql blocks), paravertebral, intercostal Plexus: Brachial plexus B, Lumbar plexus B, Cervical plexus B Distal: Wrist B, Ankle B, Median nerve B, Ilio inguinal nerve B Field & topical block

10. Local anaesthetic agent 2 classes most commonly used: Esters & Amides Mechanism of action of drugs- dose dependent blockade of sodium current in nerve fibers Different physiochemical characteristics- pKa - lower value: faster onset; commonly used agents: relatively high value protein binding- duration of action degree of hydrophobicity- proportional to potency

11. Local anaesthetic agent.. Caution- toxicity Symptoms- numbness/ tingling of tongue and lips, metallic taste, light headedness, tinnitus, visual disturbance, slurred speech, disorientation, seizures, cardio vascular collapse Prevention Aspiration before injecting Knowledge of safe dose Addition of epinephrine Treatment Oxygenation & airway support BZP/thiopental Cardio vascular support

12. Spinal Anesthesia a/k/a Subarachnoid block Indications- below umbilicus procedures Urologic, lower abdominal, perineal, lower extremity surgery Provides excellent Sensory + motor blockade below level of block Technique Position & site Induced by injection of Local anesthetic ± opiates into subarachnoid space Rapid & Predictable onset

13. Spinal Anesthesia.. Factors determining level, speed of onset and duration of spinal blockade Local Anesthetic agent Volume and dose of drug: cephalad spread Patient position and baricity of drug Vasoconstrictors Addition of opioids Anatomical and physiologic factors

14. Spinal Anesthesia.. Advantages: No manipulation of airway Avoidance of side effects of GA Several types of surgeries with good post-operative analgesia Awake patient: monitor for assessment Limitation: Single bolus injection-limited duration Complications: Hypotension, bradycardia, postdural puncture headache (PDPH), transient radicular neuropathy, backache, urinary retention, infection, epidural hematoma, excessive cephalad spread leading to cardiorespiratory compromise.

15. Spinal Anesthesia.. Limitation: Absolute contraindication Sepsis, bacteremia, infection at site of injection, severe hypovolemia, coagulopathy, therapeutic anticoagulation, increased ICP, patient refusal

16. Epidural Anesthesia Induction by injection of local anesthetics ± opiates into lumbar or thoracic epidural space Generally catheter is placed Advantages: controlled anesthesia, repeated dosing, post operative analgesia Indications- same as spinal anesthesia, adjunct to GA Special advantages: thoracic, peripheral vascular and gastrointestinal surgery Superior pain control, less sedation, better pulmonary function, less ileus Complications and limitations- similar to SA Caution: catheter care and removal, consideration with anticoagulation Epidural hematoma- back pain, sensory & motor dysfunction, bladder & bowel abnormalities.

17. Peripheral Nerve Blocks Types Truncal: Abdominal wall B (TAP), paravertebral, intercostal Plexus: Brachial plexus B, Lumbar plexus B, Cervical plexus B Distal: Wrist B, Ankle B, Median nerve B, Ilio inguinal nerve B Field & topical block Advantages Reduced physiological stress, avoidance of airway manipulation & side effects of GA Safety profile Limitations- cooperative patient, complications of LA agent.

18. What have we learnt? Types of anesthesia and classification Advantages and disadvantages Basic principles

19. Thank you Any queries?