Communication

The decision to perform PNB for ambulatory surgery patients will impact directly on a number of people in your healthcare facility. Good communication prior to commencing a PNB service is vital to ensure all members of the healthcare team are supportive of the concept.

Many surgeons are unfamiliar with PNB for anesthesia or analgesia and may feel initially uncomfortable operating on patients who are awake. They may also have experienced poor regional anesthesia practice with failed or partial blocks and apparent delays to the operating schedule. Patients may be less inclined to accept a PNB if their surgeon is unconvinced of the benefits. In our experience, a well run PNB service will result in the surgeon recommending PNB to their patients.

Nursing staff need to be familiarized with the techniques and their expected outcomes, as well as the type of assistance required. Nurses in the recovery or post-anesthesia care unit (PACU) must be aware that many patients undergoing PNB for anesthesia can bypass the PACU (79% vs 25% for general anesthesia (GA) patients), going directly to the ward. Ward nurses have to be made aware that patients can usually be discharged faster compared to patients post GA.

Consent

Patients should give their informed consent for a procedure. The relative benefits and risks of the block should be discussed with each patient so they can make their own risk/benefit analysis. Benefits include improved pain relief compared to opioids, less PONV, quicker recovery and earlier discharge from hospital compared with GA. Risks include those of local anesthetic (LA) toxicity and neural damage, which has a 1 : 10 000 chance of nerve injury persisting beyond 3 months. Minor, short-lived and expected side-effects such as paresthesia and numbness should be explained to the patient. A written record of this discussion and the patient’s agreement or not to have PNB should be recorded.

Working environment

Compared with GA, the performance of PNB takes longer to achieve anesthesia, as the time to onset includes both the time to perform the block and for the LA to act. However, a number of studies^3,4 have shown that less time is spent in the operating theatre (20 mins), the PACU (40 mins) and the hospital (40–100 mins), resulting in an overall time gain with PNB compared to GA (Fig. 8.1). There is a 20 minute increase in the amount of time the anesthesiologist spends with the patient.

Figure 8.1 Differences in time between GA and PNB in an ambulatory setting for upper limb surgery; SDCU: Surgical Day Care Unit.

From Armstrong KP, Cherry RA. Can J Anaesth 2004;51(1):41–4.

An effective schedule is required to ensure these time benefits are realized. Some suggestions are to have a second anesthesia provider (nurse anesthetist or another anesthesiologist) available who can monitor one patient while another is having a PNB placed, starting either earlier to place the PNB or commencing the operating schedule with a GA case.

The use of a dedicated block room has been advocated but this may not be cost effective unless it serves a number of operating theatres and has a regular patient load.⁴ A more practical solution is to perform the blocks in the PACU, hence utilizing the nursing staff and facilities already available.⁵

Performance of techniques

Proper preparation is vital for the safe provision of regional anesthesia and this is discussed in greater detail in another chapter of this book. Briefly, the following equipment and drugs are required (Box 8.3) and we would recommend that a dedicated regional anesthesia trolley be organized. Importantly, Intralipid must be stored as part of the emergency drugs.

Although the successful use of Intralipid for LA toxicity in humans has only been documented in case reports, the results have been so dramatic that its use is recommended. Intralipid has been effective in LA toxicity resulting from the long-acting amides bupivacaine, ropivacaine and levobupivacaine. While successful use has been described for the short-acting LA, mepivacaine, to date the only use for lidocaine has been in a pediatric patient who received both lidocaine and ropivacaine for psoas compartment block.⁶

The individual nerve block techniques are described in detail in their respective chapters. The type of block to choose for a particular surgical procedure is discussed in the relevant upper or lower limb section.

Modern peripheral nerve blockade is performed using either a nerve-stimulation technique (NST) or ultrasound guidance (USG) to locate the relevant nerves. USG for PNB is generally accepted to result in a faster onset (about 5 minutes), higher success rates (3–10% greater when compared to multi-stimulation techniques) and possibly lower LA volumes compared to NST.^7,8 However, whether these differences will result in benefit in the average ambulatory setting is debatable. The advantage of USG may be offset by its significantly increased capital cost.

Sedation has potential advantages and disadvantages. Disadvantages are mainly related to excessive sedation or loss of the airway. Advantages of sedation include a reduction in patient anxiety, increased comfort during prolonged (>1 hour) surgery and improved patient cooperation during block performance. The choice of sedation is one for each anesthesiologist, but in our experience in the ambulatory setting intravenous midazolam often negates the benefits of a PNB technique, and either low doses of fentanyl, alfentanil or propofol result in patient comfort and controlled sedation. For longer surgery, a low dose target-controlled infusion of propofol (1–2 µg/mL) is an alternative. However, continuous monitoring of respiratory effort and oxygen saturation is necessary.

Choice of local anesthetic

The main determinant of the type of LA to use is the duration of surgery. In reality, the duration of the shorter acting LAs such as the ester prilocaine (3–4 mg/kg), or amides lidocaine (4.5 mg/kg) and mepivacaine (5–6 mg/kg) is sufficient for most ambulatory surgery. The addition of epinephrine (1 : 200 000) prolongs the duration of action of lidocaine from 1–1.5 hours to 3.5–4 hours, which is equivalent to mepivacaine. Adding epinephrine also increases the permitted dose of lidocaine to 7 mg/kg.

Other adjuncts can be added – tramadol prolongs mepivacaine and clonidine increases block duration for both lidocaine and mepivacaine. Unfortunately, the doses of clonidine (2 µg/kg) required often result in sedation, which may be undesirable in a day surgery setting and delay discharge.

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

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.

Follow-up is required after discharge and must continue until there is complete resolution of the block. In practice, this usually consists of a telephone contact after 24 hours and on a daily basis thereafter if necessary, although some centers have nurses who visit patients with continuous infusions. Occasionally, the patient will have to re-attend with the anesthesiologist if there is persistence of the block or evidence of neural injury. Any suspicion of neural injury should be rapidly followed-up and confirmed. The guidelines from the Consensus Statement of the American Society of Regional Anesthesia on Neurologic Complications of Regional Anesthesia and Pain Medicine, 2005 are useful in this circumstance.¹⁵

Patient acceptance and satisfaction

Studies have demonstrated that patients’ acceptance of PNB in the ambulatory setting is very high, with 98% of patients reporting that they would have the same anesthesia technique again.^16,13 Patients’ overall satisfaction of a PNB as the principal method of anesthesia is also very high. Using a Likert scale of 1–5, Klein and colleagues found that in a study of over 1700 patients, the mean (± SD) for satisfaction with the PNB technique was 4.88 ± 0.44 at 24 hours and 4.77 ± 0.69 on day 7 post surgery.¹³

Catheters

The placement of catheters for PNB allows for continuous infusions of low dose LA, hence facilitating prolonged postoperative analgesia. This permits more major surgery to be performed in the ambulatory setting, as the patient’s pain can be managed at home. These techniques are discussed in greater detail elsewhere in this chapter.

Shoulder surgery

Common ambulatory surgical procedures on the shoulder are arthroscopy, rotator cuff repair and total shoulder arthroplasty (TSA).

The most appropriate block for shoulder surgery is an interscalene block (ISB) because of the consistent blockade of the suprascapular, dorsal scapular and axillary nerves compared with more distal blocks.¹⁷

Hadzic et al. demonstrated that for outpatient rotator cuff surgery, single shot ISB resulted in patients having less pain, earlier ambulation and discharge, with no unplanned hospital admissions, compared with patients who received general anesthesia.¹⁸

For more extensive surgery such as TSA, severe pain is common and pain control following TSA is important to allow early rehabilitation and discharge from hospital. The use of continuous ISB allows TSA to be performed as a 23-hour ambulatory procedure, with patients discharged home with portable LA pumps and catheters that are either removed by a community nurse or by the patient or their carer.¹⁹

Patients undergoing TSA who were randomized to a continuous ISB infusion with ropivacaine 0.2% were suitable for discharge a median of 30 hours (21 vs 51 hours) earlier than patients who received the saline control. They required less intravenous morphine, had less pain and had greater external shoulder rotation.²⁰

Patients undergoing TSA will still require GA and converting this type of surgery into a successful ambulatory procedure requires a well-organized system in place to follow up patients and their continuous catheters at home.²¹

The effects of ISB on pulmonary function are well known; however, there were no differences found in pulmonary function between a group of patients receiving a continuous ISB infusion and a patient-controlled morphine group.²² Using USG, it is possible to perform an ISB with 5 mL of LA, which reduces the incidence of diaphragmatic paralysis from 100% with 20 mL of LA to 45% with the lower volume.²³

The clinical significance of these changes in pulmonary function in patients without pulmonary disease is debatable and respiratory problems have not been reported in patients discharged home following ambulatory overnight TSA.²² This clinical pathway may not be appropriate for patients suffering from pre-existing pulmonary compromise.

Elbow, forearm and hand surgery

Supraclavicular, infraclavicular and axillary brachial plexus blocks are all suitable blocks for elbow, forearm and hand surgery. Mid-humeral and specific nerve blocks at the elbow, wrist and fingers may also have a role, especially in providing selective anesthesia to a particular nerve(s).²⁴

In the ambulatory setting, axillary brachial plexus blockade is often regarded as the most appropriate block because of its high success rate (>95% with USG or multi-stimulation NST) and very low complication rate.⁷ Concerns regarding the risk of pneumothorax as a complication of the infraclavicular and, in particular, the supraclavicular blocks have been raised, with some anesthesiologists uncomfortable in performing these blocks in an ambulatory setting. These concerns are largely unfounded, especially if USG is applied, which may improve safety by permitting visualization of the needle relative to the pleura and lung. It should be noted that the supraclavicular block, even with the use of USG, is only 85% effective for forearm or hand surgical anesthesia, compared with 95–98% with infraclavicular or axillary blocks.⁸

A number of randomized studies have compared PNB with GA for ambulatory hand surgery. McCartney et al. compared transarterial axillary block to GA in 100 patients undergoing ambulatory hand surgery.¹⁰ Patients who received axillary block reported a longer duration to first analgesic, had lower pain scores and opioid consumption, less nausea/vomiting and spent less time in the hospital than patients receiving general anesthesia. There was no difference in pain scores or opioid consumption on postoperative days 1, 7, and 14, however, and the axillary block had a 10% failure rate, necessitating GA in these patients. USG or multi-stimulation techniques have a failure rate of 3–5% and are recommended instead of the trans-arterial approach.

Hadzic et al. randomized 52 patients undergoing hand and wrist surgery in the ambulatory setting to receive either infraclavicular block with chloroprocaine plus epinephrine and bicarbonate or GA with propofol induction, desflurane maintenance and wound infiltration with bupivacaine. Infraclavicular block led to faster recovery times, lower pain scores (3% vs 48% with pain scores >3), four times less nausea/vomiting and earlier discharge from hospital.²⁵

For surgery on the fingers, a number of techniques for digital anesthesia have been described, including the digital or ‘ring’ block, the intrathecal digital block (injection of local anesthetic into the flexor sheath) and the metacarpal block (local anesthetic injected between and at the level of the metacarpal bones).²⁶ Digital blocks are useful if a tourniquet is not required or as selective long-acting analgesia. These are simple to perform and provide a mean duration of anesthesia of 24.9 hours with bupivacaine 0.5%, 10.4 hours for lidocaine 2% with epinephrine (1 : 100 000) and 4.9 hours for plain lidocaine 2%.²⁶ Epinephrine results in a temporary reduction in digital blood flow but with preservation of digital perfusion.²⁷ An advantage of the intrathecal block is that it involves only a single injection, has a faster onset time (3.91 vs 7.16 min) and better proximal and radial digital anesthesia than metacarpal block.²⁸ Similar findings have been reported for digital block compared to the metacarpal block.

Hip surgery

Hip surgery is one of the most common and classical orthopedic surgical procedures but at present, total hip arthroplasty (THA) is not considered an ambulatory procedure. THA results in relatively severe postoperative pain requiring hospitalization to provide potent analgesia (PCA IV morphine or regional blocks). The average duration of hospitalization after THA is classically 4 to 5 days. Femoral or lumbar plexus block (with sciatic block when indicated) can provide not only excellent anesthesia but also superb analgesia, facilitating timely discharge after THA. Using long acting local anesthetics or placing catheters in the vicinity of the nerves or plexus can achieve longer duration of analgesia. Ilfeld and colleagues reported the feasibility in five patients of converting THA into an overnight-stay procedure using a continuous psoas compartment nerve block provided at home with a portable infusion pump with a continuous infusion of ropivacaine 0.2%.³⁰ All but one patient met the discharge criteria on postoperative day (POD) 1 and three patients were discharged directly home on POD 1. Postoperative pain was well-controlled, opioid requirements and sleep disturbances were minimal, and patient satisfaction was high. Furthermore, the same group evaluated if a 4-day ambulatory continuous lumbar plexus block (LPB) could maximize ambulation distance and decrease the time required to reach three specific readiness-for-discharge criteria after hip arthroplasty, compared with an overnight continuous LPB only. They reported a 38% decrease in the time to reach the three predefined discharge criteria but not an increase in ambulation distance. This technique combined with multi-modal anesthetic and analgesic regimens with associated minimally invasive surgical approaches and rapid rehabilitation protocols, has been incorporated into the management of total joint arthroplasty surgical programs.^31,32 In a study of 665 patients utilizing this clinical pathway, Mears and colleagues reported that 38.9% of patients were discharged home with indwelling peripheral nerve catheters. Hospital discharge in less than 24 hours was achieved in 44.4%. After discharge, 73.5% of patients required no home or outpatient nursing care.³³

Knee surgery

Knee arthroscopy is well suited as an ambulatory procedure. Analgesia can be provided by intra-articular regional anesthesia and analgesia, as well as from peripheral nerve blockade. Authors evaluated the use of psoas compartment or femoral blocks for knee arthroscopy. Hadzic et al. compared patients scheduled for knee arthroscopies receiving combined psoas compartment block and sciatic nerve block or a GA.³⁴ They reported an incidence of moderate to severe PONV in 12% of patients with combined psoas compartment and sciatic blocks versus 62% with fast-track GA that included prophylactic dolasetron. Peri-operative nerve blocks reduced sore throat, increased ability to bypass phase 1 PACU, and reduced time to meet discharge criteria. Jankowski et al. found that supplemental analgesics were required in 45% of patients receiving a GA compared with only 21% receiving psoas compartment block.³⁵ In addition, the GA group had higher pain scores at 30, 60, 90, and 120 min. However, there is a risk of epidural spread attributed to the paravertebral needle insertion site and high injection pressure that can potentially impede discharge. Femoral nerve block is also used for knee arthroscopy. Better anesthesia resulted from the addition of the lateral femoral cutaneous nerve block or an obturator nerve block when compared with the femoral nerve block alone, and this provided improved intra-operative conditions.³⁶ An intra-articular injection of LA alone, a femoral nerve block alone, or a combined intra-articular and femoral nerve block provided acceptable intra-operative anesthesia, excellent surgical conditions, and similar postoperative analgesia in the study by Goranson et al.³⁷ A combination of femoral-sciatic blocks can provide more stable intra-operative hemodynamics with less hypotension, compared with GA.³⁸ In addition, this PNB combination permitted a PACU bypass compared with GA, as well as a shorter length of PACU stay. Furthermore, the femoral-sciatic block had less total anesthesia cost compared with GA. The analgesic potential of femoral nerve blocks can be demonstrated in more painful surgical procedures, such as anterior cruciate ligament (ACL) reconstruction. Mulroy et al. in a prospective study examined 55 patients having ACL repair under epidural block.³⁹ Postoperatively they received a femoral nerve block with 0.5% bupivacaine or saline. There was superior postoperative analgesia in the block group, whereas 50% of the patients in the sham group reported visual analog scale (VAS) pain scores of greater than 5 out of 10. Iskandar et al. compared a femoral nerve with intra-articular regional analgesia for patients having ACL repair with a hamstring graft.⁴⁰ They reported better postoperative pain relief in the femoral nerve block group. Nevertheless, when a hamstring graft is used for ACL repair, a significant component of postoperative pain can arise from the sciatic nerve distribution. Williams et al. strongly supported the addition of a sciatic nerve block to a femoral nerve block for more extensive knee surgery.⁴¹ In 1200 consecutive outpatients having knee surgery, they reported that single shot/continuous femoral nerve blocks alone provided little benefit for simple arthroscopy but improved analgesia and reduced unanticipated hospital admissions in ligament repairs or more complex arthroscopic knee surgery. In these patients, the addition of a single-shot sciatic nerve block conferred even better postoperative analgesia and fewer hospital admissions. For total knee arthroplasty the use of a continuous 4-day ambulatory femoral block demonstrates improved analgesic, maximizes ambulation distance and decreases the time required to reach three specific readiness-for-discharge criteria, compared to an overnight infusion only.⁴²

Foot and ankle surgery

Popliteal block provides analgesia advantages over both ankle blocks and wound infiltration after foot surgery.⁴³ Randomized studies demonstrated that duration of postoperative analgesia after popliteal block was 1080 mins, compared with 690 mins after ankle block and 709 min after subcutaneous wound infiltration.⁴⁴ The popliteal block also provided better analgesia and higher patient satisfaction. In painful foot or ankle surgery, White et al. compared prospectively a postoperative continuous popliteal block with 0.25% bupivacaine versus saline.⁴⁵ The bupivacaine group had lower VAS pain scores for 48 h, 70% less morphine consumption and a shorter length of hospital stay. Similarly, Ilfeld et al. randomized patients to receive a continuous popliteal block with 0.2% ropivacaine or saline, after an induction block with mepivacaine 2%.⁴⁶ They reported a decrease in postoperative pain, opioid requirements, opioid-related side-effects, and better sleep with fewer awakenings.