THE PAIN-CONTROL INFUSION PUMP FOR POSTOPERATIVE PAIN CONTROL IN PLASTIC SURGERY

Postoperative pain, or any pain for that matter, can be managed pharmacologically by four different approaches. The first approach is the central approach, wherein pharmacologic agents (e.g., narcotic analgesics) are administered systemically and act by altering the perception of pain in the central nervous system. This method has all of the disadvantages and risks associated with the use of these pharmacologic agents (e.g., sedation, respiratory depression, nausea and vomiting). 8 The second approach involves the use of neuraxial blockade (i.e., spinal or epidural analgesia), which acts by blocking or altering the transmission of pain impulses from the spinal cord to the brain. The disadvantages of this method include sympathetic blockade leading to possible hypotension, motor blockade possibly interfering with ambulation, urinary retention, the risk of spinal headache, and the risk of respiratory depression with the use of narcotics. The third approach is peripheral nerve blockade, such as axillary block or femoral nerve block, which acts by blocking the transmission of nerve signals to the central nervous system. The disadvantages of these methods include the complexity of performing these procedures, the risk of neuropathy with the prolonged presence of a catheter and/or local anesthetic in proximity to a major nerve, and the risks of the blocks themselves (e.g., phrenic nerve block and elevated hemidiaphragm with interscalene block). The fourth method is the application of local anesthetic at the site of injury, which blocks the transmission of pain signals at the local level. This method is safe and free of systemic side effects. The only risk associated with this method is that of local anesthetic toxicity should excessive amounts of local anesthetic be infused. This would be the method by which pain should ideally be treated if possible.

Postoperative pain control is both most critical and most difficult in the first 48 hours. In an effort to address this, local anesthetics are widely applied in a variety of plastic surgical procedures. For example, in augmentation mammaplasty, local anesthetic is commonly instilled into the pocket containing the implant just prior to closing the wound, and in abdominoplasty, local anesthetic is injected into the muscle sheath prior to closing the incision.

The pain-control infusion pump (Fig. 1) delivers a continuous infusion of local anesthetic to the surgical site. We have made the use of this type of device (Pain Control Infusion Pump, Sgarlato Labs, Los Gatos, Calif.) a routine part of our practice in a variety of procedures. In augmentation mammaplasty, just prior to closure we now place a very fine (20-gauge) multiport catheter in each pocket and have them exit through separate small stab wounds. After abdominoplasty, we place two 20-gauge multiport catheters along the rectus sheath and have them exit through the same stab wounds as the drains we place. The catheters are then connected via a Y-connector to a flow rate restrictor and then to a 100-ml spring-loaded syringe reservoir. The catheters cannot be connected to the reservoir without first connecting a flow rate restrictor, thereby preventing accidental overdosage. The flow rate restrictors are available in sizes of 0.5 ml per hour, 1 ml per hour, 2 ml per hour, and 4 ml per hour, allowing for the use of this device in a variety of surgical procedures. We use two 2-ml per hour flow rate restrictors, which each deliver a constant 2-ml per hour infusion of local anesthetic. The reservoir is filled with 100 ml of 0.25% bupivacaine with 1:200,000 epinephrine. The patient is therefore receiving 10 mg (4 ml per hour ? 2.5 mg/ml) of bupivacaine per hour or 240 mg per 24 hours. This is well below the established maximum dose of bupivacaine of 400 mg per 24 hours. 9 The catheters are left in place and continue the infusion continued for 48 hours, at which point the catheters are removed.

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We have now performed over 40 cases using this device and have found a marked reduction in postoperative pain with a concomitant decrease in analgesic use. There have been no complications related to the use of the device. An additional benefit that we have noted, but which is difficult to quantify, is an increase in patient satisfaction, because patients are virtually pain-free during the critical 48-hour immediate postoperative period and continue to have minimal pain even thereafter. Preemptive analgesia (i.e., the blocking of pain before it begins) has been shown to reduce postoperative pain even long after the preemptive analgesic technique's effect has dissipated. 10,11 This may explain the decrease in pain beyond the 48-hour infusion period. An additional benefit in these two procedures that are normally associated with pain on deep inspiration should be a decrease in respiratory complications. However, one would have to look at a far greater number of patients to determine this, because the incidence of these complications is very low.

A recent change we have made to this technique is the addition of antibiotic to the local anesthetic being infused in complicated cases such as revision or reconstructive augmentation mammoplasties, transverse rectus abdominis musculocutaneous flap breast reconstructions, or complicated abdominoplasties. In these types of procedures, we often use perioperative antibiotics, and feel that delivering the antibiotics directly to the surgical site as well as systemically would be more efficacious then simply administering them systemically. 12 Despite the local delivery of the antibiotics, there is obviously some systemic absorption as well, providing the benefits of systemic antibiotics as well. The antibiotic we have been using most commonly is cefazolin in patients not allergic to cephalosporins. We add 1 g of cefazolin to the 100 ml of local anesthetic in the pain-control infusion pump reservoir. Determining whether this results in a decrease in wound infections will require a far larger number of patients in that this is also a complication with an extremely low incidence.

In conclusion, we have found the pain-control infusion pump to be a safe and effective technique for the control of postoperative pain.

Daniel Man, M.D.

Harvey Plosker, M.D.