Complications of Neuraxial Blockade

1. Soli Deo Gloria Complications of Neuraxial Blockade Developing Countries Regional Anesthesia Lecture Series Daniel D. Moos CRNA, Ed.D. U.S.A. moosd@charter.net Lecture 13

2. Disclaimer • Every effort was made to ensure that material and information contained in this presentation are correct and up-to-date. The author can not accept liability/responsibility from errors that may occur from the use of this information. It is up to each clinician to ensure that they provide safe anesthetic care to their patients.

3. Introduction • Exaggerated physiological response • Associated with needle placement • Associated with catheter placement • Associated with medication toxicity

4. Medical Liability- In General • Administration of regional anesthesia constitutes 18% of all claims in the US • 64% are temporary and non disabling • 13% involve death • 10% permanent nerve injury • 8% brain damage • 4% are “other”

5. Medical Liability- Neuraxial Blockade • 76% of all claims were related to neuraxial blockade • Epidural’s comprised 42% • Spinal’s comprised 34% • Caudal comprised 2% • The population most affected is the obstetric population

6. Adverse or Exaggerated Physiological Response Include: • High neural blockade • Cardiac arrest • Urinary retention

7. Adverse or Exaggerated Physiological Response • This category is an extension of “normal” physiologic manifestations. • The main point is vigilance and early treatment. Treat hypotension early and do not let it progress to cardiac arrest. • Knowledge, preparation, and anticipation can help reduce adverse or exaggerated physiological responses

8. High Neural Blockade • Can occur with either spinal or epidural techniques

9. High Neural Blockade Causes • Excessive doses of local anesthetic are administered • Failure to reduce dose in patients susceptible to excessive spread (i.e. the elderly, pregnant, obese, or short patients) • Unusual sensitivity • Unusual excessive spread

10. High Neural Blockade • Constant monitoring of the patients vital signs and block level are imperative • Use of alcohol wipes (to assess cold sensation) and/or pinprick test will help • Incremental dosing is important with an epidural • With hyperbaric techniques you can change the patients position to slow down the cephalad spread (i.e. reverse Trendelenberg)

11. High Neural Blockade-Prevention • Careful consideration in dosing your block • Anticipation of potential complications • Plan of action if complications occur • Continual monitoring of the patient as the block progresses

12. High Neural Blockade- Initial Symptoms • Dyspnea • Numbness and tingling of the upper extremities (i.e. fingers) • Nausea generally precedes hypotension due to hypoperfusion of the chemoreceptor trigger zone • Mild to moderate hypotension

13. High Neural Blockade- Initial Treatment • Change position with hyperbaric technique • Stop the administration of local anesthetics with an epidural technique • Supplemental oxygen • Open up the IV fluids • Treat hypotension with ephedrine or phenylephrine • Treat bradycardia

14. High Neural Blockade- Initial Treatment • Choose your vasopressor carefully. • If patient is hypotensive and bradycardic then ephedrine would be indicated • Ephedrine will increase heart rate as well as constrict blood vessels • Phenylephrine can result in reflex bradycardia as it constricts blood vessels • If patient is hypotensive and tachycardic or normal in respect to heart rate then phenylephrine may be indicated

15. High Neural Blockade- Initial Treatment • Refractory hypotension and/or hypotension should be treated rapidly with 5-10 mcg of epinephrine

16. High Neural Blockade- Spread to Cervical Dermatomes Signs and Symptoms May Include: • Severe hypotension • Bradycardia • Respiratory insufficiency including apnea • Unconsciousness

17. High Neural Blockade- Cervical Dermatomes Treatment • The A,B,C’s • Airway and breathing- supplemental oxygen, maintain a patent airway, intubation, mechanical ventilation • Circulation- aggressive intravenous fluid administration, ephedrine, phenylephrine, epinephrine • Bradycardia should be treated with atropine • Dopamine infusions may help

18. High Neural Blockade- Cervical Dermatomes Treatment • Early and aggressive treatment may help avoid a cardiac arrest! • Once patient has been stabilized and successfully treated the decision to proceed is based on individual circumstances • Considerations include time spent hypotensive, indications of myocardial ischemia, etc. • The respiratory compromise associated with high neural blockade are often transient

19. Cardiac Arrest Due to Neuraxial Blockade

20. Cardiac Arrest Due to Neuraxial Blockade • Cardiac arrest can occur with either epidural or spinal anesthesia • More common with spinal anesthesia and the incidence may be as high as 1:1,500 • Usually preceded by bradycardia • Can easily occur in the young and healthy

21. Cardiac Arrest Due to Neuraxial Blockade- Keys to Prevention • Appropriate hydration (i.e. 1 liter to an average sized adult)- must be administered within approximately 15 minutes since the majority of crystalloid solution will leave the intravascular space • Aggressively treat bradycardia, atropine, ephedrine, epinephrine • Do not be fooled by the 26 year old marathon runner- patients with a slow heart rate and high vagal tone are at risk for cardiac arrest during spinal anesthesia • Total sympathectomy with unopposed vagal stimulation • Error on the conservative and treat the patient

22. Cardiac Arrest Due to Neuraxial Blockade- Risk Factors • Baseline heart rate < 60 bpm • ASA class I • Use of Beta Blockers • Sensory level > T6 • Prolonged P-R interval

23. Urinary Retention

24. Urinary Retention • Due to blockade of S2-S4 • Leads to a decrease in bladder tone and inhibition of normal voiding reflex • Neuraxial opioids may contribute to urinary retention • More common in elderly men and those with a history of benign prostatic hypertrophy

25. Urinary Retention • Urinary catheterizes should be provided for patients undergoing moderate to lengthy procedures • Postoperative assessment is important to detect urinary retention • Prolonged urinary retention may be a sign of serious neurological injury

26. Complications Associated with Needle Placement or Catheter Insertion • Inadequate anesthesia or analgesia • Inadvertent intravascular injection • Total spinal • Subdural injection • Backache • Postdural puncture headache • Neurological injury • Spinal or epidural hematoma • Meningitis and arachnoiditis • Epidural abscess • Sheering off the tip of the epidural catheter

27. Inadequate Analgesia or Anesthesia • Rate of block failure is low but can be frustrating • Must always be prepared to convert to general anesthesia or supplement • Rate of block failure decreases as experience increases

28. Inadequate Analgesia or Anesthesia- May be associated with: • Outdated or improperly stored local anesthetics (tetracaine looses potency when stored for long periods in a warm environment)

29. Inadequate Analgesia or Anesthesia- May be associated with: • Needle movement once free flowing CSF is noted- helpful to confirm aspiration before, during, and after injection • Even with free flowing CSF it is possible that the spinal needle is not entirely in the subarachnoid space resulting in a partial subdural injection and partial spinal

30. Inadequate Analgesia or Anesthesia- May be associated with: • Epidural anesthesia is more subjective since you have to rely on confirmation by loss of resistance or hanging drop technique • Either technique can lead to false positives • Spread of local anesthetic is less predictable

31. Inadequate Analgesia or Anesthesia- May be associated with anatomical factors with epidural • Soft spinal ligament can occur in the very young and in obstetrics…this results in never achieving a good loss of resistance • If you are off the midline slightly you may be in the paraspinous muscle and not in the spinal ligaments

32. Inadequate Analgesia or Anesthesia- May be associated with anatomical factors with epidural • Block failure may occur if the epidural catheter migrates into the subdural space • Injection of local anesthetics into this space may result in Horner’s syndrome, a high spinal, or an absence of any effect

33. Inadequate Analgesia or Anesthesia • Local anesthetic toxicity can occur if the epidural catheter is placed into a vessel • A high spinal can occur if the epidural catheter is placed in a subarachnoid space- stresses importance of the test dose

34. Inadequate Analgesia or Anesthesia • Septations within the epidural space may create a barrier to the spread of local anesthetic and some segments may lack anesthesia • L5, S1, S2 are all large nerve roots and the large size may prevent penetration of local anesthetic- correct by making the area dependent and adding local anesthetic

35. Inadequate Analgesia or Anesthesia • Visceral pain can occur even if the epidural is adequate. Visceral afferent fibers travel with the vagus nerve. • May increase the level of epidural anesthesia to the thoracic levels with additional local anesthetic • IV sedatives and opioids may help

36. Inadequate Analgesia or Anesthesia- Failed Epidural • Not waiting long enough to let it work • Catheter is inserted too far resulting in a “unilateral” block…pull back the catheter 1-2 cm and add local anesthetic with the unaffected side down

37. Inadvertent Intravascular Injection • Risk with spinal anesthesia is extremely low • Risk generally lies with epidural or caudal anesthesia • Toxicity will affect the central nervous system and cardiovascular system

38. Inadvertent Intravascular Injection • Local anesthetics vary in their potential to cause toxicity • Least to most toxic local anesthetics are as follows: • Chloroprocaine< lidocaine < mepivacaine < levobupivacaine< ropivacaine < bupivacaine

39. Inadvertent Intravascular Injection- Symptoms • Hypotension • Arrhythmias • Cardiovascular collapse • Seizures • Unconsciousness

40. Inadvertent Intravascular Injection- Prevention • Test dose • Careful aspiration prior to injection • Incremental dosing • Vigilant monitoring for early signs and symptoms of intravascular injection • Early symptoms include increase heart rate (if epi used), tinnitus, funny taste or metallic taste, subjective changes in mental status

41. Inadvertent Intravascular Injection- Prevention • With early symptoms stop administration and anticipate impending complications such as seizures and hypotension, etc. • Re-evaluate placement of catheter and reinsert as needed

42. Local Anesthetic Toxicity Treatment • Standard ACLS treatment • Bretyllium may be more effective than other forms of antiarrhythmics

43. On the Horizon- Intralipids • Several successful resuscitations of local anesthetic overdose as well as other lipophilic medication overdoses • Local anesthetics are amphipathic (have an affinity for both lipid and water) • This makes local anesthetics potentially toxic for several tissues including the heart, brain, and skeletal muscles

44. On the Horizon- Intralipids • Intralipids expand the lipid compartment and allow for local anesthetic binding (there are more involved and technical explanations but lets keep it simple)

45. Lipid Rescue Protocol (Experimental) • 20% Intralipid • 1.5 mg/kg initial bolus • 0.25 mg/kg/min infusion for 30-60 minutes • Bolus may be repeated 1-2 times for persistent asystole • May increase infusion rate if blood pressure decreases • See lipidrescue.com for more information

46. Subdural Injection • Subdural space is a potential space that is found between the dura and arachnoid space • It contains a small amount of serous fluid • Subdural space extends from the epidural space to the intracranial space • Local anesthetics can travel further in the subdural space than they can in the epidural space

47. Subdural Injection • Small doses of local anesthetic can travel far in the subdural space • Small doses of local anesthetic associated with a spinal may result in no local anesthetic blockade • Larger doses of local anesthetics associated with epidural analgesia may result in Horner’s Syndrome

48. Subdural Injection • Manifestations of Horner’s syndrome include miosis (constriction of the pupil); ptosis (drooping of the upper eyelid); and anhidrosis (diminished or absent sweating).

49. Horner’s Syndrome

50. Subdural Injection • Larger doses of local anesthetics associated with epidural anesthesia may result in a total spinal. • Prevention is slightly more difficult as aspiration will generally be negative • With slow incremental dosing you may note a higher and faster progression of blockade than would be normally expected