SPINAL ANESTHESIA by DR NIKHIL VORUGANTI

brief discussion about spinal anesthesia
spinal anaesthesia
anesthesia
lumbar puncture

1. SPINAL ANESTHESIA PRESENTOR : DR VORUGANTI NIKHIL KUMAR

2. INTRODUCTION Spinal anesthesia involves the use of small amounts of local anesthetic injected into the subarachnoid space to produce a reversible loss of sensory and motor function

3. ANATOMY VERTEBRAL COLUMN CONSISTS OF 7 CERVICAL VERTEBRAE 12 THORACIC VERTEBRAE 5 LUMBAR VERTEBRAE 5 SACRAL VERTEBRAE 4 COCCYGEAL VERTEBRAE The spinal cord is enclosed in the vertebral column, It extends from the foramen magnum where it is continuous with the medulla to the level of the L1 in adults and around levels L3 in infants The spinal cord terminates in a tapering cone shaped structure called as conus medullaris

4. Cauda equina Cauda equina refers to  the bundle of nerve roots located at the lower end of the spinal cord, which extend beyond the termination of the spinal cord at the first lumbar vertebra . The cauda equina exists within the  lumbar cistern , a gap between the arachnoid membrane and the  pia mater  of the spinal cord, called the  subarachnoid space

5. Therefore, performing a lumbar (subarachnoid) puncture below L1 in an adult (L3 in a child) usually avoids potential needle trauma to the cord And damage to the cauda equina is unlikely, as these nerve roots float in the dural sac below L1 and tend to be pushed away (rather than pierced) by an advancing needle

6. Layers of spinal cord SKIN SUBCUTANEOUS TISSUE SUPRA SPINOUS LIGAMENT INTERSPINOUS LIGAMENT LIGAMENTUM FLAVUM EDPIDURAL SPACE DURA MATER ARACHNOID MATER SUBARACHNOID SPACE PIA MATER

7. DERMATOMES A DERMATOME IS A AREA OF SKIN INNERVATED BY SENSORY FIBRES FROM A SINGLE SPINAL NERVE Cervical nerves.  There are eight pairs of these Cervical nerves, numbered C1 through C8. They originate from your neck. Thoracic nerves.  You have 12 pairs of thoracic nerves   that are numbered T1 through T12 Lumbar nerves.  There are five pairs of lumbar spinal nerves, designated L1 through L5. Sacral nerves.  Like the lumbar spinal nerves, you also have five pairs of sacral spinal nerves. Coccygeal nerves . You only have a single pair of coccygeal spinal nerves.

8. Dermatomal level of spinal anesthesia for common surgical procedures

9. indications Lower abdominal surgeries Inguinal surgeries Urogenital surgeries Rectal surgeries Lower extremity surgery

10. absolute 1) Infection at the site of injection 2) Patient refusal 3) Coagulopathy or other bleeding diathesis 4) Severe hypovolemia 5) Increased intracranial pressure 6) Severe aortic stenosis or Severe mitral stenosis 1)Sepsis 2) Uncooperative patient 3)Preexisting neurological deficits 4)Demyelinating lesions 5)Stenotic valvular heart lesions 6)Left ventricular outflow obstruction 7)Severe spinal deformity relative contraindications

11. Dura splitting Whitacre needle Sprotte needle Quincke babcock needle Pitkin needle Dura cutting Spinal needles

12. positions SITTING POSITION LATERAL DECUBITUS POSITION TUFFIE R S LINE

13. Approaches of spinal anesthesia 1)Midline Approach - The most common approach, the needle or introducer is placed midline, perpendicular to spinous processes, aiming slightly cephalad . 2)Paramedian Approach - Indicated in patients who can not adequately flex because of pain or whose ligaments are ossified, the spinal needle is placed 1.5 cm laterally and slightly caudad to the center of the selected interspace.

14. Midline Approach The most common approach, the needle or introducer is placed midline, perpendicular to spinous processes, aiming slightly cephalad

15. Paramedian Approach Indicated in patients who can not adequately flex because of pain or whose ligaments are ossified, the spinal needle is placed 1.5 cm laterally and slightly caudad to the center of the selected interspace.

16. Drugs used in spinal anesthesia LIDOCAINE Onset of action occurs in 3 to 5 minutes with a duration of anesthesia that lasts for 1 to 1.5 hours Rapid onset of action , intermediate duration and low toxicity Disadvantages — Transient neurological symptoms

17. BUPIVACAINE One of the most widely used local anesthetics O nset of action is within 5 to 8 minutes, with a duration of anesthesia that lasts from 90 to 150 minutes

18. OTHER DRUGS USED IN SPINAL ANESTHESIA Tetracaine 0.5% Mepivacaine 2% Ropivacaine 0.75% Levobupivacaine 0.5% Chloroprocaine 3%

19. ADJUVANTS USED IN SPINAL ANESTHESIA Produce intense visceral analgesia and prolong only sensory blockade 1)Opioids - Lipophilic agents such as fentanyl and sufentanil have a much more localized effect ,rapid onset of action and an effective duration greater than 6 hours. 2)CLONIDINE-alpha 2 agonist (150ug) Onset -same Duration-prolonged 3)Epinephrine- vasoconstrictor action delays absorption of local anesthetic 4)Phenylephrine-1:1,000 concentration

20. MECHANISM OF ACTION Interacts with the receptor situated within the voltage sensitive sodium channel and raises the threshold of channel opening Decreases the entry of sodium ions during upstroke of action potential Local depolarization fails to reach the threshold potential and conduction block is acheived

21. LEVELS OF BLOCK

22. Complications of spinal anesthesia INTRA OPERATIVE COMPLICATIONS POST OPERATIVE COMPLICATIONS HYPOTENSION RESPIRATORY IMPAIRMENT TOTAL SPINAL BLOCK NAUSEA AND VOMITING POST DURAL PUNCTURE HEADACHE INFECTIONS

23. PHYSIOLOGIC EFFECTS OF SPINAL CORD

24. AUTONOMIC BLOCKADE The sympathetic nervous system (SNS) is described as thoracolumbar since sympathetic fibers exit the spinal cord from Tl to L2. The parasympathetic nervous system (PNS) has been described as cranio sacral since parasympathetic fibers exit in the cranial and sacral regions of the CNS. The end result of neuraxial blockade is a decreased sympathetic tone with an unopposed parasympathetic tone. This imbalance will result in many of the expected alterations of normal homeostasis noted with the administration of spinal anesthesia .

25. CARDIO VASCULAR EFFECTS Spinal blockade can impact the cardiovascular system by causing the following changes: 1)Decrease in blood pressure (33% incidence of hypotension in non-obstetric populations) 2)Decrease in heart rate (13% incidence of bradycardia in non-obstetric populations) 3)Decrease in cardiac contractility

26. Respiratory effects Spinal blockade plays a very minor role in altering pulmonary function. Even with high thoracic levels of blockade, tidal volume is unchanged. There is a slight decrease in vital capacity. This is the result of relaxation of the abdominal muscles during exhalation. The phrenic nerve is innervated by C3-C5 and is responsible for the autonomic movement of diaphragm. The phrenic nerve is extremely hard to block, even with a high spinal, apnea associated with a high spinal is thought to be related to brainstem hypoperfusion and not blockade of the phrenic nerve. This is based on the fact that spontaneous respiration resumes after hemodynamic resuscitation has occurred

27. Renal effects Neuraxial blockade effectively blocks spinal control of the bladder at the lumbar and sacral levels Urinary retention can occur due to the loss of autonomic bladder control. Detrusor function of the bladder is blocked by local anesthetics. Normal function does not return until sensory function returns to S3

28. Management of COMMON complications OF SA HYPOTENSION Increase the rate of administration of IV fluids Oxygen supplementation until BP restores back to optimal levels Vasopressors Ephedrine sulphate Mephenteramine Phenylephrine Epinephrine Norepinephrine BRADYCARDIA - Administer Atropine Respiratory impairment or Total Spinal - Intubate and ventilate the patient with 100% Oxygen

29. POST DURAL PUNCTURE HEADACHE Post dural puncture headache is a common potential complication of a lumbar puncture, with symptoms caused by traction on pain-sensitive structures from low cerebrospinal fluid pressure (intracranial hypotension) following a leak of cerebrospinal fluid at the puncture site

30. pdph Incidence - 10% to 40% of LP procedures, but can be as low as 2% when small gauge (less than or equal to 24 gauge) non-cutting needles are used It is postural and it is often fronto -occipital associated with stiff neck , nausea, vomiting , dizziness and photophobia. Pathophysiology-Loss of CSF at a faster rate than it can be produced causing traction on the structures supporting brain, particularly dura It is aggravated by sitting or standing and decreased or relieved by lying down Flat.

31. MANAGEMENT CONSERVATIVE MANAGEMENT - BED REST , HYDRATION , ANALGESICS , ANTI EMETICS AGGRESSIVE MEDICAL MANAGEMENT - THEOPHYLLINE, CAFFEINE ,OCCIPITAL NERVE BLOCK EPIDURAL BLOOD PATCH RECONSIDER DIAGNOSIS , FIBRE GLUE SURGERY

32. ADVANTAGES OF SPINAL ANESTHESIA 1)Cost - The costs associated with SPA are minimal. 2)Respiratory disease - Spinal anesthesia produces few adverse effects on the respiratory system as long as unduly high blocks are avoided. 3)Patent airway - As control of the airway is not compromised, there is a reduced risk of airway obstruction or the aspiration of gastric contents 4)Diabetic patients-There is little risk of unrecognized hypoglycemia in an awake patient.

33. REFERENCES MORGAN AND MIKHAIL CLINICAL ANESTHESIOLOGY - 6 TH EDITION MILLERS ANESTHESIA - 9 TH EDITION NYSORA BJA COLLINS REGIONAL ANESTHESIA

34. THANK YOU ANY QUESTIONS ?