Wound local anesthetic infusions

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CHAPTER 13 Wound local anesthetic infusions

Placing local anesthetic in or close to the surgical wound has become a popular method of providing intra- and postoperative analgesia. The technique is applied by a single injection or by continuous infusion using an indwelling catheter. Wound infusions can be an important component of the multi-modal approach to postoperative pain relief. They have been shown to have a significant opioid-sparing effect. For more minor surgical incisions, such as those used for arthroscopic surgery, local anesthetic infusions alone may provide adequate analgesia.

Local anesthetic infusions are more practical now with the development of portable infusion devices. Catheters with multiple holes or permeable membranes disperse local anesthetic over a wider area. These techniques have the advantage of simplicity of performance and, to date, are considered to be safe. The equipment needed, of course, adds to the cost of the procedure but these costs may be offset by a shorter stay in hospital and increased patient satisfaction.

Crile, a surgeon from Cleveland, USA, was the first to describe, in 1913, the benefit of local anesthesia application to the surgical wound in providing analgesia and decreasing morbidity and mortality. Capelle, in 1935, described the use of an infusion apparatus to deliver local anesthesia to the wound.¹ In 1950, Blades and Ford used a fine catheter to deliver local anesthetic to thoracotomy wounds.

Over the past 20 years, numerous papers have reported the use of local anesthesia in wounds of major abdominal incisions, gynecological and obstetric procedures, orthopedic operations, plastics procedures and mastectomy, among others. These studies have confirmed a decrease in pain scores at rest and during activity. They have, in addition, been associated with a decreased incidence of side-effects.²

Rationale for using local anesthetic infusion

Postoperative pain arises from the interaction of three factors:

1 Impulses generated from injured nerve fibers innervating the site of surgery.

2 Inflammatory mediators, such as prostaglandins and cytokines are at increased concentrations at the surgical site and sensitize nerve fibers.

3 Sensitization of pain-transmitting pathways in the spinal cord that elevates their responsiveness to non-painful stimuli such as pressure or touch. Prolonged peripheral sensitization as a result of surgery can result in central sensitization. This is thought to be a significant cause of chronic postoperative pain.³

Local anesthetics can be used peri-operatively to affect all three of the above.⁴ In addition, because these systems are relatively simple to use they can and have been used in the home setting postoperatively.⁵

Mechanisms of action

Local anesthetics are known to block impulse transmission in all peripheral nerves by virtue of their ability to block sodium channels and thus inhibit conduction in the nerve axon. Infiltration of local anesthetic around the site of surgery can suppress the generation and propagation of injury-induced discharge from ectopic foci in injured nerves. Continuous infusion of slow release formulations of local anesthetic may extend such inhibition for days after surgery.

In addition, it is now apparent that systemic concentrations of local anesthetic i.e. lignocaine 2–4 µg per mL for only a few hours peri-operatively can have an analgesic effect postoperatively for a number of days. The mechanism for this is unknown at present.

Local anesthetics have an anti-inflammatory action also, through their effects on cells of the immune system, as well as on other cells, e.g. microorganisms, thrombocytes and erythrocytes.

Potential problems

Initial fears regarding the potential risks of infection and effects on wound healing would appear to be unfounded, as studies have not shown any adverse effects on wound healing or increased rates of infection.

Local anesthetics are known to have myotoxic properties, but in concentrations used for infusion these have not been observed to date.

It would appear that local anesthetic infusions have very few side-effects and as a result their risk–benefit ratio is positive.²

Positioning

To date most catheters are placed in position by the operating surgeon under aseptic conditions. Aseptic placing of the catheter is obviously essential and great care regarding asepsis must be taken when recharging the infusion system.

The fact that surgeons place catheters has the added advantage of making them more aware of postoperative pain and empowering them to assist its palliation. Postoperative pain has up to recently not been seen as a complication in surgical terms. The incidence of post-surgical chronic pain is higher than many surgeons appear to realize.⁶

Catheters can be placed in the wound itself or at some distance from the incision. Because of fear of infection, it is advocated by some that it is better to place the catheter outside the wound. The optimal positioning will depend on the direction of the nerve supply to the area. It may require the use of two catheters if there is a nerve supply from both sides, as in the chest for example.

In the abdomen, catheters should be placed in the muscle plane in which the nerve supply runs. These will be dealt with in more detail in the individual sites below.

Orthopedic procedures

Shoulder surgery

Arthroscopic surgery

Wound catheter techniques decrease opioid requirements without significant side-effects.

Subacromial catheter placement is recommended (Fig. 13.1) but intra-articular catheters have also been used. A flow rate of 2–5 mL/hr is adequate.

Figure 13.1 Subacromial placement of catheter.

Open shoulder surgery

There are fewer reports on the use of local anesthetic infusions in open shoulder surgery than on arthroscopic procedures; however, it appears that continuous wound infusions do have an opioid-sparing effect. A preclosure bolus of local anesthetic is also recommended. Flow rate of 5 mL/hr is sufficient in most cases. A higher concentration of local anesthetic (0.375%) may be required compared with arthroscopic surgery (0.25%).

Joint surgery

Anterior cruciate ligament reconstuction (ACLR)

A bolus injection into the joint of 20–25 mL followed by a continuous infusion at both the donor site and intra-articularly appears to give the best result. Pain control is enhanced by the addition of morphine 5 mg and /or ketorolac 30 mg. Infusion for 48 hours is recommended at a flow rate of 10 mL/hr intra-articularly and 2 mL/hr in the wound.

Total knee replacement

As in the ACLR above, both intra-articular and subcutaneous parapatellar catheters are recommended. A fenestrated catheter is suggested because of the length of the wound, with a flow rate of 5 mL/hr, preceded by a bolus dose into the wound layers.

More recently, a high dose local infiltration technique has been described. This combines the use of local anesthetics together with an anti-inflammatory agent and adrenaline in the tissues around the wound and also the use of an intra-articular catheter.⁷

Total hip arthroplasty

Here also, postoperative continuous wound infusions have been shown to be effective. If the wound is especially long, 2 fenestrated catheters may be necessary; again, preceded by a bolus injection to the layers of the wound. The optimum technique has yet to be determined, however.

Injection of 20 mL of local anesthetic to the peri-capsular area combined with a catheter on the tensor fascia lata has produced excellent results, in the author’s experience.

Abdominal surgery

Laparotomy with mid-line incision ⁸

This is a common surgery and is associated with severe postoperative pain, especially if the wound is above the umbilicus. Incisions below the umbilicus tend to be less painful. Nevertheless, the incisions for open laparotomy can be long, and therefore a fenestrated catheter is recommended. It would appear that subfascial placement is more effective than subcutaneous (Fig. 13.2).⁹ The length of catheter can be adjusted for the size of the incision. A bolus is suggested prior to infusion.

Figure 13.2 Catheter placement for mid-line incisions.

Flow rates depend on the size of the wound. Flow rates of up to 10 mL/hr maybe necessary for longer incisions.

Sub-costal incisions

Again, a subfascial placement is recommended, with flow rates of at least 4 mL/hr using a fenestrated catheter.

Laparoscopic cholecystectomy

The current recommended technique for this surgery is the use of a 20-mL bolus in the gallbladder bed and in the trocar sites, followed by intermittent 10-mL boluses intraperitoneally. An epidural catheter is sufficient here. Infusions do not appear to add any benefit.¹⁰

Note, this technique does not relieve shoulder pain.

Appendicectomy via McBurney’s incision

The technique for open laparotomy, i.e. subfascial placement of the catheter, is also recommended here.

Nephrectomy

Studies are scarce here, but placement of a fenestrated catheter between the oblique muscles has been shown to be effective.

Inguinal herniotomy

A subfascial placement of the catheter has demonstrated efficacy. Low flow rates, i.e. 2 mL/hr are sufficient, if preceded by a bolus injection to the incision or by the use of an ilioinguinal block.

Breast surgery

Postoperative use of continuous indwelling catheters has been shown to be of benefit in many types of breast surgery, including mastectomy, plastic/cosmetic procedures and axillary clearance.¹¹

Multi-holed catheters are recommended, and placed in the superior aspect of the wound to allow for gravity to aid distribution of the local anesthetic. The use of drains may negate the benefit of the infusion.

A study placing the catheter parallel and inferior to the axillary vein has been shown to be effective for axillary surgery.¹²

The catheter has been placed behind the breast implant in augmentation surgery and has been found to be effective.

The use of a bolus injection prior to infusion of c.4 mL/hr for 48 hours is also recommended.

Cardiothoracic surgery

Current evidence suggests that the use of two fenestrated catheters, one placed in the subfascial plane above the sternum and the other subcutaneous in the wound, is effective in reducing pain at rest, and opioid consumption.¹³

Flow rates of 2 mL/hr in each catheter are recommended for at least 48 hours.

Gynecological/obstetrical surgery

Cesarian section

Cesarian section through a Pfannenstiel incision is associated with less postoperative pain when local anesthetic is perfused via a fenestrated catheter placed either above or below the fascia.¹⁴ The optimal position is as yet undetermined. Diclofenac alone infused to the wound was found to be superior to intravenous diclofenac.¹⁵

As with other incisions, it is probably best to have a preclosure bolus before commencing the infusion.

Infusion rates of 4–6 mL/hr should suffice unless the wound is very wide.

This technique is especially beneficial in these patients, as early mobilization is preferable.

Abdominal hysterectomy

This procedure has also been shown to be associated with less postoperative pain and decreased opioid consumption when a wound infusion of local anesthesia has been used.¹⁶ Placement of the catheter above the fascia has been more effective than below the fascia, which is at variance with other abdominal surgeries when subfascial placement of the catheter has been more effective. Further studies will confirm the optimal catheter position.

Equipment

The basic system is a pump (Figs 13.3 and 13.4) and a catheter. Sterile equipment and aseptic technique are essential to minimize the risk of infection.

Figure 13.3 Elastometric pump empty.

Figure 13.4 Elastometric pump filled.

Pumps include elastomeric and battery driven types. Some elastomeric pumps are fitted with flow restrictors and clamps to prevent overdose. Nevertheless, these do not always prevent accidental emptying of the pump and do not alert personnel to changes in flow rate. Pumps housed in a protective rigid plastic cover are less prone to external pressure that may result in an increase in flow rate.

Catheters should be available in different lengths to provide for wounds of varying length. They should be multi-holed and facilitate uniform flow and even distribution of drug over the length of the wound.

Drugs

Robivicaine and levobupivicaine are the most commonly studied local anesthetics for continuous infusions. These are associated with less toxicity and are the recommended drugs. Levobupivicaine is most commonly used in a concentration of 0.25%, while robivicaine has been used in similar concentrations, but some authors have recommended 0.375%.

There is some concern over possible cytotoxic effects of local anesthetics on articular chondrocytes or osteoblasts; however, this needs further evaluation.¹⁷

Diclofenac given by continuous infusion to the wound has been shown to give more effective pain relief and have a greater opioid-sparing effect than giving the same dose intravenously. However, this needs further study and is not recommended until more is known about its use in this situation.

1 Capelle W. Die Bedentung des Wundschmerzes und seiner Ausschaltung fur dan Ablauf der Atmung bei Laparotomierte. Dtsch Z Chir. 1935;246:466.

2 Liu SS, Richman JM, Thirlby RC, Wu CL. Efficacy of continuous wound catheters delivering local anaesthetic for post operative analgesia: a quantitative and qualitative systematic review of randomised controlled trials. J Am Coll Surg. 2006;203:914-932.

3 Kehlet H, Jensen TS, Woolf CJ. Persistent post surgical pain: risk factors and prevention. Lancet. 2006;367:1618-1625.

4 Strichartz GR. Novel ideas of local anaesthetic actions on various ion channels to ameliorate post operative pain. BJA. 2008;101(1):45-47.

5 Rawal N, Axellson K, Hylander J, et al. Postoperative patient-controlled local anaesthetic administration at home. Anaesth Analg. 1998;86:86-89.

6 McRae WA. British Journal of Anaesthesia. 2001;87(1):88-98.

7 Röstlund T, Kehlet H. High dose local infiltration analgesia after hip and knee replacement-what is it, why does it work and what are the future challenges? Acta Orthop. 2007;78:159-161.

8 Beaussier M, E’Ayoubi H, Schiffer E, et al. Continuous preperitoneal infusion of robivicaine provides effective analgesia and accelerates recovery after colorectal surgery. A randomised double-blind, placebo-controlled study. Anaesthesiology. 2007;107:155-159.

9 Fredman B, Zohar E, Tarabyk A, et al. Bupivicaine wound installation via an electronic patient-controlled device and a double catheter system does not decrease postoperative pain or opioid requirement after major abdominal surgery. Anaesth Analg. 2001;92:189-193.

10 Gupta A, Thöm S, Axelsson K, et al. Postoperative pain relief using intermittent injections of 0.5% ropivacaine through a catheter after laparoscopic cholecystectomy. Anaesth Analg. 2002;95:450-456.

11 Rawal N, Gupta A, Helsing M, et al. Pain relief following breast augmentation surgery: a comparison between incisional patient-controlled regional analgesia and traditional oral analgesia. Eur J Anaesthesiol. 2006;23:1010-1017.

12 Schell SR. Patient outcomes after axillary node dissection for breast cancer: use of postoperative continuous local anaesthesia infusion. J Surg Res. 2006;134:124-132.

13 Dowling R, Theilmeier K, Ghaly A, et al. Improved pain control after cardiac surgery: Results of a randomised double blind clinical trial. J Thorac Cardiovasc Surg. 2003;26:127-128.

14 Ranta PO, Ala-Koko TI, Kukkonen JE, et al. Incisional and epidural analgesia after caesarian delivery: a prospective, placebo-controlled, randomised clinical study. Int J Obstetric Analgesia. 2006;15:189-194.

15 Lavand’homme PM, Roelants F, Waterloos H, de Kock MF. Postoperative pain analgesic effects of continuous wound infiltration with diclofenac after elective Caesarian delivery. Anaesthesiology. 2007;106:220-225.

16 Gupta S, Maheshwari R, Dulara SC. Wound instillation of 0.25% bupivacaine as continuous infusion following hysterectomy. Middle East J Anaesth. 2005;18:595-610.

17 Karpi JC, Chu CR. Lidocaine exhibits dose-and time-dependent cytotoxic effects on bovine articular chondrocyes in vitro. Am J Sports Med. 2007;35:1621-1634.

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