*3.1.1. Morphine*

1‐h and/or 4‐h limits, depending on the equipment configuration, it has the function to limit the total cumulative dose in the period of 1 or 4 h in order to reduce the adverse effects and

Considering the advances in the development of drug delivery systems, the use of infusion pumps for patient‐controlled analgesia (PCA) and analgesia epidural catheter with opioids are considered the most powerful strategies to control of postoperative pain. However, there

The basal opioid administration doses may be administered concurrently with the adminis‐ tration of opioids by PCA techniques. However, the basal administration increases the risk of respiratory depression without providing necessarily an additional analgesia pattern [19].

PCA different modalities can minimize the occurrence of gaps in analgesic administration, supplying analgesic dosage immediately after the system activation, providing more uniform analgesia and eliminating painful waiting periods between the patient's request and drug

Electronic PCA pumps have several models in the market, including small portable devices nowadays. Since the first commercially available PCA pump ("Cardiff Palliator"), PCA devices have evolved enormously in technological sophistication, ease of use, flexibility and

Currently, IV‐PCA is one of the most used techniques for acute pain control. Its use is suit‐ able for virtually any patient undergoing surgery that are cursed with postoperative pain of moderate or severe intensity [18]. Many studies have demonstrated the efficacy, safety, and patient satisfaction with PCA intravenously. A meta‐analysis involving 115 randomized clinical trials demonstrated that this technique provides greater efficacy when compared to intramuscular administration of analgesics [20]. Another study showed that, among patients who received IV‐PCA, 36% experienced moderate to severe pain in the first 24 h after surgery when compared to 67% of important painful experience among patients who received intra‐ muscular opioids [21]. Moreover, it was verified that the IV‐PCA is associated with a higher

Despite the possibility that IV‐PCA may be combined to a basal opioids infusion, it was shown that the incidence of respiratory depression with IV‐PCA was much smaller (0.19% versus 0.29%) when compared to the combination of this technique with systemic infusion of

IV‐PCA is associated with potential complications inherent in the technique, which are opera‐ tor‐dependent. Errors may occur in the drug administration, usually by programming failures

are doubts about the advantages and limitations of these different forms of PCA.

ensure the patient safety [11, 18].

50 Pain Relief - From Analgesics to Alternative Therapies

administration.

portability.

**3. PCA modalities**

**3.1. Intravenous PCA (IV‐PCA)**

rate of patient satisfaction [22].

opioids (1.09–3% versus 8%) [23].

Morphine is the most common opioid used for IV‐PCA and it is considered the gold standard for this procedure. Although many studies have demonstrated its clinical safety, adverse effects such as nausea, vomiting, itching, urinary retention, sedation and respiratory depression may occur. Its active metabolite morphine‐6‐glucuronide (M6G) have analgesic action but presents risk of adverse effects. As the M6G has renal elimination, the use of morphine should be done with caution in patients with impaired renal function and the elderly [34, 35]. The low thera‐ peutic index of morphine in IV‐PCA was shown in preclinical models, indicating that morphine cannot be the best option for all patients for pain relief in the postoperative period [31].

The usual morphine dose and the recommended parameters are: demand dose: 1–2 mg; lock‐ out period: 6–10 min; continuous basal infusion dose: 0–2 mg/h [11].

## *3.1.2. Hydromorphone*

Hydromorphone has been used in patients with impaired renal function or with a history of allergy to morphine. It is mainly metabolized by the liver and it is, approximately, five times more potent than morphine. Clinical effects of hydromorphone are dose‐dependent and its adverse event profile is morphine‐like [11, 36]. A systematic review of adverse events associated with the postoperatory use of six different opioids (buprenorphine, fentanyl, hydromorphone, meperidine, morphine, and sufentanil) showed that after meperidine (proscribed, 67.9%), the opioid with the highest incidence of central nervous system side effects was hydromorphone (42.7%). Furthermore, at higher doses, hydromorphone can cause excitation [37].

Due to the similarity between morphine and hydromorphone, errors have been reported in programming the IV‐PCA pump. Considering that these agents have significant differences in their clinical potency, inadvertent hydromorphone administration can result in serious complications [38].

Doses and recommended parameters are: demand dose: 0.2–0.4 mg; lockout period: 6–10 min; continuous basal infusion dose: 0–0.4 mg/h [11].
