1. Complications of Local Anesthetic Techniques
By Dr. Mahmoud Abdelkhalek

2. Complications of Local Techniques
Spinal& epidural anesthesia:
Hypotension
Nerve Injury
Infection and Hematoma
Peripheral Nerve Blocks
Local Anesthetic Systemic Toxicity

3. Hypotension Mechanism: Signs include:
Arterial and venous dilatation caused by sympathetic pharmacological denervation reduce cardiac afterload and preload
Systemic hypotension results, and may be severe enough to compromise organ perfusion
Signs include:
Tachycardia
Low BP
Confusion
Nausea
Dizziness

4. Hypotension Treatment:
Fluid preloading may reduce the incidence of hypotension
Left lateral position is helpful in pregnant patients
Intravenous titration of a vasopressor agent (e.g. bolus doses of ephedrine 5 mg or metaraminol 1 mg) usually restores arterial pressure rapidly
Directly acting arterial constrictors are more appropriate than indirectly acting sympathomimetics if tachycardia is present and in patients with severe ischemic heart disease

5. Nerve Injury
Nerve injury may result from direct trauma caused by the needle, or through chemical toxicity
Epidural and subarachnoid block should be undertaken in the conscious patient; to allow early identification of impingement upon a nerve or the spinal cord

6. Infection and Hematoma
Spinal abscess:
A devastating complication of central nervous blockade
Presents as sudden, painless loss of motor function, usually several days after performance of the block
Meticulous aseptic technique helps to reduce the incidence of this complication but some cases arise spontaneously, probably as a result of bacteremia caused by surgery and inoculation of a small and otherwise asymptomatic epidural hematoma
Urgent magnetic MRI and referral to a neurosurgeon are indicated if spinal abscess is suspected

7. Infection and Hematoma
Epidural hematoma:
A common complication of epidural catheter placement
The large majority of hematomata are asymptomatic and resolve spontaneously
They may be apparent only upon spinal imaging
Large hematomata may cause permanent nerve injury

8. Infection and Hematoma
Epidural catheters should not be inserted in patients who are receiving warfarin or intravenous heparin, or who have abnormal coagulation for some other reason
Caution should be exercised if a patient is receiving low- dose heparin for thromboprophylaxis
At least 12 h should be allowed to elapse between administration of low-molecular-weight heparin prophylaxis and epidural block
Often, imaging is delayed because numbness and weakness are attributed to the effects of the epidural block; low concentrations of local anesthetic (e.g. 0.1% or 0.125% bupivacaine) do not cause weakness and cause minimal numbness, and there should be a high level of suspicion about the possibility of epidural hematoma if these signs arise in the postoperative period

9. Infection and Hematoma
If blood is obtained via the needle or catheter during insertion and the patient is expected to be fully heparinized (e.g. during cardiac or major vascular surgery), the procedure should be postponed for 24 h
As with spinal abscesses, urgent imaging and referral to a neurosurgeon are indicated

10. Peripheral Nerve Injury
Peripheral nerves may be injured directly, through peripheral nerve blockade or vascular catheter insertion or surgery, indirectly, by poor positioning during anesthesia, or through ischemia during severe hypoxemia or hypotension
Peripheral nerve injury occurs during 0.1% of anesthetics. The position of the patient during general anesthesia is the commonest cause of injury
The brachial plexus and superficial nerves of the limbs (ulnar, radial and common peroneal) are the most frequently affected nerves
The usual mechanism of injury to superficial nerves is ischemia from compression of the vasa vasorum by surgical retractors, leg stirrups or contact with other equipment
Ischemic injury is more likely to occur during periods of poor peripheral perfusion associated with hypotension or hypothermia
Nerve injury may occur as part of a compartment syndrome after ischemia from poor positioning, particularly when the legs are placed in Lloyd-Davies supports and the patient is positioned head-down

11. Peripheral Nerve Injury
Nerves may also be injured by traction (e.g. the brachial plexus during excessive shoulder abduction)
Meticulous care is necessary when positioning the patient. Padding should be used beneath tourniquets and to protect pressure points
Extreme joint positions should be avoided
Close surveillance of tourniquet ischemia times is essential
Although many injuries recover within several months, all patients with a peripheral nerve injury must be referred to a neurologist for assessment and continuing care
Many ulnar nerve palsies occur in patients with an anatomical predisposition, and this may be deduced from a history of numbness after sleep or as a result of posture at work
In these patients, the elbows should not be placed in flexion during surgery

12. Peripheral Nerve Blocks
There is a risk of direct damage to nerves in association with any peripheral nerve block
Paraesthesia or pain in the distribution of a nerve are signs of the proximity of a nerve and should prompt needle withdrawal
Pain during injection of local anesthetic, failure to abolish the muscular twitch from a nerve stimulator or the requirement for increased injection force may indicate intraneural positioning of the needle and should prompt immediate cessation of injection and withdrawal of the needle

13. Systemic Toxicity
Occurs by accidental intravascular injection, LA overdose, or unexpectedly rapid absorption
Systemic toxicity manifests itself mainly at CNS and CVS
CNS effects first appear to be excitatory due to initial block of inhibitory fibres; subsequently, block of excitatory fibres

14. Systemic Toxicity CNS effects (in approximate order of appearance):
Numbness of tongue
Tremors
Perioral tingling
Convulsions
Disorientation
Seizures
Drowsiness
Generalized CNS depression
Tinnitus
Coma
Visual disturbances
respiratory arrest
Muscle twitching

15. Systemic Toxicity

17. Systemic Toxicity: Precautions
Intravenous access should be secured and adequate resuscitation equipment and drugs should be immediately available before a local anesthetic block is undertaken
The patient should be adequately monitored
The lowest dose of the least toxic drug available should be used to achieve the effect required (Table )

18. Local Anesthetic Toxicity: Precautions

19. Systemic Toxicity: Precautions
Local anesthetics should always be injected slowly with repeated aspiration for blood, and with constant verbal contact and observation of the patient
Any change in the patient’s apparent mental state should prompt immediate cessation of injection
Injection of a test dose of a local anesthetic which contains adrenaline usually results in sudden tachycardia if intravascular injection has occurred
The addition of adrenaline reduces the speed of absorption from tissues, allowing larger maximum doses, reducing the potential for toxicity and prolonging the action of the local anesthetic

20. Treatment of LA systemic toxicity
Use the A, B, C’s for the management of local anesthetic toxicity
A= airway Maintain a patent airway, administer 100% oxygen
B= breathing May need to be assisted with positive pressure ventilation or intubation
C= circulation Check for a pulse If no pulse, initiate CPR

21. Treatment of LA systemic toxicity
Convulsions are very common in significant toxicity and administration of an anticonvulsant (e.g. diazepam 10 mg, thiopental 50 mg) is often necessary

22. Treatment of LA systemic toxicity
Hypotension: (Fluids+ Vasopressors)
Rapid infusion of IV fluids
Place the patient in a head down position (Trendelenburg)
Phenylephrine shots or infusion
Ephedrine (typically 5 mg shots)
If refractory treat the patient with epinephrine (5-10 mcg shots)
Repeat and escalate the dose as necessary

23. Systemic Toxicity: Treatment
Arrhythmias may occur and should be treated appropriately
Severe heart block may require an infusion of isoprenaline or pacing
Chest compressions are required if there is no palpable pulse
Survival from local anesthetic toxicity should approach 100%

24. Questions?