Long-acting LAs such as levobupivacaine and ropivacaine are generally not used because of the prolonged motor blockade. The use of a continuous technique allows lower doses to be used, providing a motor sparing effect, and is useful for more major ambulatory surgery such as shoulder arthroplasty.⁹ There are no studies in the ambulatory setting comparing the duration of analgesia of long- versus short-acting LAs, but it is reasonable to assume that the benefits seen with long-acting LAs for in patients would be similar. Performing selective analgesic blocks with a long-acting LA while using a short-acting LA for the main block and anesthesia, is an effective technique (for example, for a Dupuytren’s contracture, performing an axillary block with mepivacaine and an ulnar block at the elbow with levobupivacaine).

Multi-modal analgesia

The duration of analgesia provided by PNB is usually longer than the duration of anesthesia, but, depending on the choice of LA or if a single shot technique is performed, this may be limited to 6–8 hours post-block. Importantly, patients’ perception of pain post block resolution is often much higher than would otherwise be anticipated. This is most likely as a result of the loss of profound analgesia following block resolution.

Therefore a multi-modal approach to analgesia is required. The use of acetaminophen and non-steroidal anti-inflammatories (NSAIDs), both prior to and regularly post block resolution, is effective in clinical practice. Oral opioids may be required, depending on the type and extent of surgery.

Postoperative care

The postoperative management of patients who receive a PNB in an ambulatory setting is particularly important, as they will be discharged relatively earlier from the healthcare facility.

Although there has been some debate regarding the feasibility and safety of discharging a patient home with an insensate limb, general consensus is that patients can be discharged if some basic principles are followed.

Firstly, the anesthesiologist has to be prepared to accept the clinical situation. Even with short-acting LAs, 50% of patients will have residual block present when they are otherwise fit for discharge home.¹⁰ The discharge criteria normally used for patients undergoing GA, such as the modified Aldrete score, are inappropriate because they require the patient to move all four limbs.¹¹ A scoring system not requiring limb movement, such as the Postanesthesia discharge scoring system (PADSS), may have to be incorporated into your practice¹² (Table 8.1).

Table 8.1 Post-anesthesia discharge scoring system (PADSS) for determining home readiness

Discharge criteria	Score
Vital signs:
Vital signs must be stable and consistent with age and pre-operative baseline
Blood pressure and pulse within 20% of pre-operative baseline	2
Blood pressure and pulse 20–40% of pre-operative baseline	1
Blood pressure and pulse >40% of pre-operative baseline	0
Activity level:
Patient must be able to ambulate at pre-operative level
Steady gait, no dizziness, or meets pre-operative level	2
Requires assistance	1
Unable to ambulate	0
Nausea and vomiting:
Patient should have minimal nausea and vomiting before discharge
Minimal: successfully treated	2
Moderate: successfully treated with intravenous medication	1
Severe: continues after repeated treatment	0
Pain:
Patient should have minimal or no pain before discharge
The level of pain that the patient has should be acceptable to the patient
Pain should be controllable by oral analgesics
The location, type and intensity of pain should be consistent with anticipated postoperative discomfort
Pain acceptable	2
Pain controllable with oral analgesics	1
Pain not acceptable	0
Surgical bleeding:
Postoperative bleeding should be consistent with expected blood loss for the procedure
Minimal: does not require dressing change	2
Moderate: up to two dressing changes required	1
Severe: more than three dressing changes required	0
TOTAL

Maximum score = 10.

Patients scoring ≥ 9 are fit for discharge.

Modified after Chung F, Chan VW, Ong D. J Clin Anesth 1995;7(6):500–6.

Secondly, discharging a patient home with a long-acting LA block is safe. A study of 1791 patients who underwent a total of 2382 blocks of both the upper and lower limb, with ropivacaine 0.5% in a day surgery setting, found an incidence of paresthesia of 0.25% at 7 days. All had resolved by 3 months. One patient fell getting out of a car following combined femoral and sciatic nerve blocks, with no sequelae.¹³ Another study found no difference in the incidence of paresthesia at 1 year when comparing axillary block with GA for hand surgery.¹⁴

Finally, the patient must be given both verbal and written instructions in the care of the insensate limb. An example information sheet is included (Box 8.4). It should be explained that the limb is numb and must be cared for and protected from injury and temperature extremes until the limb returns to the patient’s own normal sensation and motor function. The use of a sling (upper limb) or crutch (lower limb) is a useful visual reminder. Patients should also be given details of how long the block is expected to last, as well as a contact telephone number should the block persist outside defined parameters, which will depend on the type of LA and/or continuous technique used.

Box 8.4

Patient information sheet post upper limb block

Name of your Hospital

Day Surgical Unit

Department of Anesthesiology