Introduction

An “anesthetic complication” may be defined as any deviation from the normally expected pattern during or after the securing of regional analgesia.

Can be divided into 2 groups:

Those attributed to solutions used e.g. toxicity, idiosyncrasy, allergy, anaphylactoid reactions, infection caused by contaminated solutions, local irritation or tissue reaction

Those attributed to insertion of needle e.g. syncope, muscle trismus, pain or hyperalgesia, edema, infections, broken needles, hematoma, sloughing etc.

LOCAL COMPLICATIONS:

Needle breakage
Persistent anesthesia or paraesthesia
Facial nerve paralysis
Trismus
Soft tissue injury
Hematoma
Pain on injection
Burning on injection
Infection and edema
Sloughing of the tissue
Post anesthetic intraoral lesions

SYSTEMIC COMPLICATIONS:

Toxicity
Idiosyncracy
Allergy
Anaphylactoid reaction
Syncope

NEEDLE BREAKAGE

Become rare because of the use of disposable needles

Causes:

Bending of the needle.
Multiple usage( to be used for not more than 3-4 penetrations )
Change in path of insertion or forcing the needle against resistance
Sudden unexpected movement by the patient (esp. if movement is opp. to that of needle)
Smaller gauge
Defective manufacturing (extremely rare)
Prevention:

Use correct gauge – 25 gauge
Long needles – prevent penetration till hub
Not to redirect when in tissue

Management:

Instruct patient not to move and do not remove your hand. Try to keep the patients mouth open. If required place bite block
If fragment is visible, remove it with a hemostat
If fragment lost, inform the patient and allay fears and apprehension
Radiograph advised, if superficial it can be removed, but if located deep within the tissues, refer to a specialist

PERSISTENT ANESTHESIA OR PARAESTHESIA

Causes:

Trauma to the nerve
Injection of LA contaminated with alcohol or sterilizing solution
Hemorrhage in and around the nerve sheath
Problems:
Persistent anesthesia – usually rare
Biting / thermal / chemical insult – without patient awareness
When lingual nerve is involved – taste impaired
Prevention:
Proper care & handling of dental cartridge
Adherence to injection protocol

Management:
Reassurance
Resolution begins in 8 weeks and takes about a year.
Periodic recall & check up of patients every 2 months
Persistent even after 1 year – consult neurosurgeon

FACIAL NERVE PARALYSIS

Cause:
LA solution into parotid gland – usually while giving INAB, Akinosi technique
Paralysis of its terminal branches during the infraorbital block or during canine infiltration

Problems:
Ipsilateral loss of motor control not more than several hours till the effect of anesthetic persists
Drooping of lip, inability to close eye lid

Prevention:
Needle tip to contact bone, redirection of needle to be done only after withdrawal
Avoid over insertion in Akinosi technique

TRISMUS

Trismus derived from the Greek word trismos, It is def. as the prolonged tetanic spasm of the jaw muscles by which the normal opening of the jaw is restricted.
Causes:
Trauma – to muscle / blood vessel
Irritating solution
LA solution is known to have slight myotoxicity
Hemorrhage
Infection
Multiple needle punctures
Excessive volume – distension of tissues
Problems:
In acute cases may lead to pain and decreased mobility
In Chronic cases trismus is due to organization of hematoma, fibrosis and scar contracture

Prevention:
Use of sharp, sterile, disposable needle
Aseptic technique
Practice atraumatic methods
Avoid repeated injections
Use minimum volume
Control infection

Management:
Heat therapy
Warm saline rinses, moist hot packs
Analgesics
NSAIDs, Codeine (30-60mg), muscle relaxants
Initial physiotherapy
Opening and closing the mouth and lateral excursions for 5 minutes, every 3-4 hr
Post pone treatment unless urgent
Antibiotic regime given if the pain and discomfort persists beyond 48 hrs as in such cases infection is suspected.

SOFT-TISSUE INJURY

Causes:

Soft tissue anesthesia lasts longer than pulpal anesthesia and this may lead to injury to the patient in the absence of sensory perception

Problems:

Trauma to anesthetized areas leading to swelling and significant pain

Prevention :

LA of appropriate duration to be selected.

 Cotton rolls secured with floss and warn the patient against eating, drinking hot fluids,

Management:

Analgesics, antibiotics, warm saline, petroleum jelly 

HEMATOMA

Causes:

Arterial & venous puncture – common in PSA & IANB

Patients with bleeding disorders

Problems:

Bruise – may / may not be visible extra-orally

Complications – pain & trismus

Swelling & discoloration which usually subsides within 7- 14 days

Prevention:

Knowledge of normal anatomy – proper technique

Modify techinque according to anatomy, e.g. shorter needle – PSA

Minimize the number of penetration

Management:

Immediate – apply firm pressure, for not less than 2 min.

INAB– medial aspect of ramus

Infra orbital, Mental, Incisive block – directly over foramen

PSA – pressure on soft tissue with finger as posteriorly as tolerated  by patient .. medial superior direction

Patient to be reviewed after 24 hours, advice analgesics, cold application upto 4-6 hours, warm- pack application next day

PAIN ON INJECTION

Causes:

Careless technique

Dull needle/ needle with barbs

Rapid deposition

Problems:

Increases anxiety, may lead to sudden unexpected movement

Prevention:

Use topical anesthetics

Adhere to proper techniques

Use sharp needles

Inject slowly and use sterile agents and at room temperature

BURNING ON INJECTION

Causes:

             pH of the solution

Rapid injection

Contamination of LA cartridges

Problems:

pH  normalizes upon LA action and therefore no residual effect

Contaminated solution may lead to other complications like trismus, edema, paraesthesia

Prevention:

Slow injection – 1ml / minute

Cartridge stored at room temperature