Chapter 10: Pain assessment and management
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Complications
Complications can:
- be drug related
- arise from the insertion of the needle or the presence of the indwelling catheter.
Drug related: local anaesthetic systemic toxicity
Systemic toxicity results from the effects of local anaesthetic drugs on the central nervous system and the cardiovascular system. This may occur if excessive doses are given or if the CPNB catheter has migrated into a blood vessel and the dose of local anaesthetic reaches the systemic circulation, which can cause very serious effects on the neurological, respiratory and cardiovascular systems. Management of severe toxicity is outlined in Figure 10.7.
Figure 10.7 Safety guideline: management of severe local anaesthetic toxicity. Source: Reproduced from AAGBI ([1]) with permission of the Association of Anaesthetists of Great Britain and Ireland.
The signs and symptoms of systemic local anaesthetic toxicity are:
- light‐headedness
- circumoral numbness or numbness of the tongue
- tinnitus or visual disturbances
- muscular twitching
- drowsiness
- unconsciousness
- convulsions
- coma
- respiratory depression
- cardiovascular depression.
Insertion of the needle or catheter
Other complications can be related to the insertion of the needle or catheter (Box 10.4).
Box 10.4
Complications relating to continuous peripheral nerve blocks (CPNB)
Bleeding
The risk of bleeding increases with the age of the patient, routine thromboprophylaxis and frequent use of antihaemostatic drugs, including platelet inhibitors. Caution should be exercised in all patients with impaired coagulation, particularly around the timing of catheter removal.
Nerve injury
This may occur as a result of insertion of the needle or catheter during the CPNB. Most nerve injury results in residual paraesthesia only, and most of these resolve over time. However, there can be a more significant and often permanent injury. Examples include:
- spinal cord damage following injection of local anaesthetic into the cord during interscalene blocks under general anaesthesia
- pneumothorax following brachial plexus blockade.
Infection
CPNB indwelling catheters carry a risk of infection. The risk increases with duration of use.
Catheter or pump related
Problems with equipment may occur at any time. Simple problems include a kinked catheter or tubing. More complex problems may also occur, such as pump errors, or the catheter breaking and leaving a residual portion in the patient.
There are currently no national guidelines on the care and monitoring of patients who have received a single‐injection regional analgesia block rather than a continuous infusion. Nurses are advised to follow local guidelines on monitoring these patients post‐procedure. Considerations should include the following:
- Has the patient received an opioid? If so, what is the drug, what is the dose and what is the expected duration of effect?
- Assessment of the injection site for evidence of bleeding or haematoma.
- Assessment of the limb or affected area for sensory function and, if appropriate, motor function, and evidence of return to normal baseline function.
