**8. Advantages of analgesic administration by intravenous (IV) PCA**

The analgesia by intravenous administration of opioids is superior in that the route of administration is easy to establish, and the onset of effect is rapid. When used for postoperative analgesia, IV-PCA should be connected after maintaining a certain concentration in the blood by the time the patient awakens from anesthesia. Fentanyl is often used, but morphine is more common worldwide. Because of the short duration of effect of fentanyl, IV-PCA with continuous administration of fentanyl is often used, and one should watch for sedation and respiratory depression. Considering that postoperative pain decreases over time, continuously administered fentanyl should be tapered off over time. Patients should be advised that a single bolus dose of PCA is unlikely to relieve severe pain and that they should not tolerate pain but should press the PCA button "at the point of onset of pain" or "at the point one feels uncomfortable." As has been mentioned earlier, it is important to note that acetaminophen and nonsteroidal anti-inflammatory drugs (NSAIDs) are available as basal analgesics.

Administration of narcotics also increases postoperative nausea and vomiting (PONV). PONV on the day following surgery is as high as 6.9% in the epidural anesthesia group versus 21.6% in the IV-PCA group [14], suggesting the active use of antiemetics so that PONV does not hinder early mobilization.

Drug addiction has become a problem in the United States. In the United States, in patients who become chronic drug users after surgery, an association was found between the patient behavior and pain disorder [15]. It is now clear that patients with a predisposition become chronic users of easily prescribed opioids following surgery, regardless of whether the surgery is major or minor, and that careless prescribing of opioids should be discouraged. In particular, respiratory depression can be fatal in obese patients and patients with chronic obstructive pulmonary disease and sleep apnea. Opioid-free anesthesia [16, 17] has proven effective for such patients.

## **9. Advantages of peripheral nerve block**

In recent years, the launch of a series of echo machines that allow for more detailed checks has made it possible to administer local anesthesia or place a catheter after

*Changes in Postoperative Analgesia DOI: http://dx.doi.org/10.5772/intechopen.109771*

confirming the nerve during peripheral nerve blocks. In the past, local anesthesia was often administered blindly using a blood vessel or bone as a landmark or by attaching a nerve stimulator to the needle tip and administering local anesthesia where the needle tip felt a muscle contraction, which could lead to inadequate effect or complications from blood vessel or direct nerve puncture. Now that the nerves can be seen directly, nerve blocks can be performed more peripherally and only where necessary. Since nerve blocks can be performed at any site where blood flow can be stopped from the surface of the body, even while the patient is on anticoagulants, there are fewer restrictions based on the patient's condition.

#### **10. Program for enhanced recovery after surgery**

To help patients undergoing surgery to recover fast and be discharged from the hospital, perioperative management through a program for enhanced recovery after surgery, known as ERAS (Enhanced Recovery After Surgery), has been implemented in Europe [18–24]. This is a multidisciplinary program that includes postoperative pain management, early mobilization, and early oral intake. The program started in 1999 with a report that postoperative hospital stay for sigmoid colon resection was reduced from the previous 5–10 days to a median of 2 days [25]. Since then, the European Society for Clinical Nutrition and Metabolism has taken the lead in promoting the use of this program, and many studies were conducted to review the timing of preoperative oral intake, bowel preparation, and the start of postoperative oral intake. The program places importance on the team approach to healthcare, in which preoperative, intraoperative, and postoperative management is seamlessly carried out through multidisciplinary collaboration. Furthermore, being up-to-date is what makes this program appealing; for example, epidural anesthesia for laparotomy, which was strongly promoted at the beginning, is no longer strongly recommended for routine surgeries [21, 24], and multimodal analgesia is now being considered, which combines the use of wound infusion catheter and subarachnoid opioids and so on.

#### **11. Delirium**

Generally, muscle weakness occurs at a rate of about 1–3% per day or 10–15% per week while the patient remains at bed rest and is said to deteriorate to 50% in 3–5 weeks. Muscle weakness can easily lead to frailty and sarcopenia in the elderly. Development of postoperative delirium is a major obstacle in the implementation of the ERAS program and early discharge from the hospital. Postoperative delirium is a serious postoperative complication that prolongs hospital stay and worsens prognosis [26, 27]. Postoperative delirium can also cause postoperative cognitive decline [28] and threatens subsequent social life. It has been reported that 80% of elderly patients develop postoperative delirium while in the intensive care unit (ICU) [29]. Postoperative delirium occurs in the elderly and is also associated with brain vulnerability. Factors contributing to delirium can be divided into (1) predisposing factors, (2) triggering factors, and (3) direct factors. Predisposing factors include advanced age, dementia, alcoholism or polydipsia, and history of psychiatric illness. Triggering factors include psychological stress, ICU stay, sleep deprivation, and postoperative pain. Direct factors include dehydration, infection, and electrolyte imbalance. Despite screening based on risk factors at the time of admission, focused care of patients prone to delirium, environmental modification, and elimination of causes, delirium still develops at a high rate in the elderly. Pharmacotherapy using psychoactive drugs is given for symptomatic treatment. Haloperidol, quetiapine, and risperidone are used [30]. However, there is no evidence of efficacy of these psychoactive drugs with respect to duration and severity of delirium, length of hospitalization, and mortality [31].

There are numerous reports on the efficacy of dexmedetomidine in the prevention and treatment of delirium [32–34]. New sleep medications, ramelteon and suvorexant, have also been reported to have preventive and therapeutic effects [35–37] and are increasingly prescribed on regular basis rather than as-needed. At our institution, we hypothesized that heart-rate variability could be used to predict delirium, and we have found that changes in autonomic nerves on the day before surgery can help predict delirium [38].
