neuraxial.pptx

hehe

1. Neuraxial Anesthesia Christabelle ileana L. Toh

2. Introduction Subarachnoid or intrathecal anesthesia is commonly referred to as spinal anesthesia commonly referred to as spinal anesthesia Caudal block -injection into the caudal epidural space via the sacral hiatus

3. Introduction Subarachnoid anesthesia - small dose of local anesthetic -rapid - done in the lumbar region, below the termination of the spinal cord. - last 2 to 3 hours at most.

4. Introduction   Epidural anesthesia -larger doses of local anesthetic -Longer time to establish. -catheter is in the epidural space , -performed in the lumbar, thoracic, cervical regions. -provide postoperative analgesia - minimal motor block .

5. Introduction Contraindications : patient refusal, coagulopathy, hemodynamic instability infection at the site of injection.

6. Anatomy 33 vertebrae: 7 cervical, 12 thoracic, 5 lumbar, 5 fused sacral, and 4 fused coccygeal.

7. Meninges

8. Cerebrospinal fluid

9. Technique Patient Preparation

10. Equipment- Before inducing assemble all of the equipment needed Positioning- Sitting Lateral Prone ( anorectal , jack knife)

11. Approach

12. Subarachnoid spinal anesthesia

13. Epidural anesthesia identified with either the hanging drop or loss of resistance technique Air- simple; easier to recognize an accidental or intentional dural puncture or an intrathecal catheter Epidural Catheter- provision of epidural anesthesia or analgesia for as long as needed

14. Combined Subarachnoid Spinal Epidural spinal anesthesia and epidural catheter are placed concurrently/ needle-through-needle technique combines the rapid onset and intense sensory anesthesia of a spinal anesthesia with ablity to supplement and extend the duration of block afforded by an epidural catheter

15. Choice of Technique Subarachnoid anesthesia-rapid onset of dense sensory block , surgeries < 2 hours Epidural anesthesia- slower in onset, post-op analgesia

16. Subarachnoid anesthesia Pharmacology Density and dose determine the spread and duration of subarachnoid anesthesia Baricity is the ratio of two densities Isobaric – Stays where you put it Hypobaric – “Floats” up Hyperbaric – Settles to Dependent aspect of the subarachnoid space

17. DOSE -greater the dose higher is the block . VOLUME- Increasing the volume of fixed concentration will also lead to higher blocks BARICITY-height of block is likely to extend a few segments higher when hyper baric solutions are used . POSITION -sitting position:-heavy solutions tends to fall, hypobaric solutions tend to rise - Iateral position:- hyper baric solution move cephalad or caudal depending upon the tilt of table. RATE OF INJECTION- injection produces higher block than expected LEVEL OF INJECTION does not appear to influence the spread of hyperbaric solutions

18. PATIENT FACTOR- CSF VOLUME- inversely propotional to the block height. OLD AGE- increased block height as CSF volume decreases PREGNANCY-lower dosages are required . ANATOMIC SPINE CONFIGRATION- - Drug travels along gravity to the most dependent part

19. Adjuvants Vasoconstrictors :epinephrine or phenylephrine α2-agonists clonidine and dexmedetomidine opioids (fentanyl or sufentanil ) morphine

20. Epidural Anesthesia FACTORS INFLUENCING SPREAD OF ANAESTHETIC SOLUTION IN EPIDURAL SPACE - Dose, volume and concentration of local anesthetic used -Patients age-Older patient requires less than the younger ones -pregnant or abdominal tumors- will develop more extensive block - Site of injection -major impact on the spread of epidural block. Small

21. Onset and Duration sensory block within 5 to 10 minutes. full extent usually within 20 to 30 minutes chloroprocaine , lidocaine , mepivacaine - shortest duration bupivacaine and ropivacaine - slowest onset but the longest durations

22. Adjuvants Sodium Bicarbonate- raises the pH, speeds the onset and increases the density Epinephrine induces vasoconstriction, decreases systemic absorption of local anesthetics α 2-Agonists- speeds the onset and improves the quality Opioids- also speed the onset and improve the quality of block

23. Test Doses -to prevent Misplaced injection of epidural catheters - When inducing inject a small dose of local anesthetic through the catheter and look for signs of subarachnoid anesthesia. - most widely used intravenous test dose is lidocaine with epinephrine.

24. Prevention and Treatment Volume Vasopressors- Ephedrine , phenylephrine , norepinephrine

25. Complications Backache- accidental dural puncture Headache - Due to leak of CSF from dural defect - Postural in nature -Most develop 24 to 72 hours after dural puncture -Occur in frontal or occipital region

26. Complications Headache - tx : prophylactic epidural blood patch, intrathecal catheter, and epidural morphine injection, analgesics High Block/Total Subarachnoid Spinal Block - can produce both cardiac and respiratory instability - tx : Support airway and circulation

27. THANK YOU