**3.4. Other modalities of patient‐controlled analgesia**

## *3.4.1. Transdermal*

Other drugs have been used by some authors that are normally associated with morphine. Ketamine, which is an agonist of the NMDA receptor, and naloxone, which is an antagonist of opioid receptors, have shown conflicting results regarding the safety or quality of analgesia,

Epidural patient‐controlled analgesia (EPCA) is the second most significant method used and studied within the PCA approach. Its use is mainly for control of acute postoperative pain, commonly in patients undergoing orthopedic, abdominal and thoracic surgery [12]. EPCA allows the use of opioids, local anesthetics, or a combination of both. Opioids epidural administered provide greater analgesic potency when compared to equivalent doses of opioid

Although both opioids and local anesthetics represent feasible options, local anesthetics are the most appropriate strategies for patients sensitive to the opioids adverse effects, even though it is associated with a higher incidence of hypotension, motor block and urinary retention com‐ pared with the use of opioids [53]. Similarly to the PCA intravenous technique, EPCA allows patients to administer the medication in accordance with analgesic requirements. There is large evidence indicating that the EPCA represents a safe and effective method [46, 54]. A meta‐anal‐ ysis concluded that, regardless of the drug chosen, epidural provides a better analgesia pattern

In a population‐based study of 2276 surgical patients, Kim et al. [56] discloses that ropivacaine with fentanyl was able to provide good quality analgesia for up to 48 h after the several surgical

Unlike IV‐PCA, the use of continuous infusion, coupled with the demand dose, have shown excellent results with minimal complications. Small doses of local anesthetics of long action combined with low doses of opioids (i.e., fentanyl or sufentanil) with continuous infusion rate associated with increments *bolus* may be combined [57, 58]. The following concentrations are recommended: bupivacaine: 0.05–0.125%; levobupivacaine: 0.05–0.125%; ropivacaine: 0.1–0.2%. Additionally, the following doses are recommended: demand dose: 2–4 ml; lockout:

Despite many advantages, EPCA also has limitations, especially considering the complexity of the procedure and technical staff training. In addition, there are reports of catheter migra‐ tion which may lead to failure in the procedure in 17% of cases. It has been suggested that this technique has great effectiveness but it should be used with caution considering individual

There are several techniques that use catheters for the purpose of providing postoperative analgesia with little or no opioid use. In this model of patient‐controlled regional analgesia, local anesthetics (ropivacaine, bupivacaine or levobupivacaine) are normally administered

and more studies are needed so that they can get their recommended use [18].

**3.2. Epidural PCA**

administered intravenously [53].

54 Pain Relief - From Analgesics to Alternative Therapies

when compared to intravenous PCA technique [55].

10–20 min; continuous basal infusion: 4–10 ml/h [11].

factors, in order to ensure patient safety [56].

**3.3. Patient‐controlled regional analgesia**

procedures, with limited side effects [56].

The iontophoretic fentanyl system (IONSYS; Ortho‐McNeil, Raritan, NJ, USA) is a prepro‐ grammed noninvasive method of PCA, which does not require venous access for drug admin‐ istration. By adhesively secured to the outside of the arm or chest of the patient, fentanyl is transferred iontophoretically through intact skin. The system allows the transdermal admin‐ istration of the drug for 10 min and a 10 min lockout interval between administrations [39].

However, the fentanyl dose administered over time is not constant. Whereas the target dose for the desired effect of fentanyl is 40 µg, it is estimated that the average dose is 16 µg after the initial application. Therefore, it would take a long period of time until the optimal dose is reached. Many patients do not receive adequate analgesia for up to 10 h after the start of the application [39].

Although clinical studies have suggested that the use of transdermal fentanyl could show simi‐ lar efficacy to morphine in PCA intravenously in relation to the overall control of pain [12], there was a need for additional analgesia in 40% of patients involved in the first 3 h of treatment. Moreover, there were local side effects such as skin redness in about 60% of cases. This system was not marketed in the U.S. and it was withdrawn from the European market by the manufac‐ turer due to a manufacturing error in some units [38].
