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Abdominal and Perineal Surgery

Although outside the thorax, operations on the upper abdomen such as cholecystectomy compromise pulmonary function. Other associated morbidity (that may lead to mortality) includes immobility, hypercoagulability, venous thrombosis, and increased myocardial oxygen consumption when pain leads to an increase in blood pressure or rapid heart rate. Patients who undergo major vascular surgery frequently have coexisting myocardial disease, wide swings in blood pressure as their major vessels are clamped and unclamped, and significant fluid shifts associated with blood loss and replacement. These patients are particularly at risk for postoperative myocardial infarctions and arrhythmias. For operations on the abdominal aorta, intraoperative epidural anesthesia is widely used and simplifies the transition to postoperative epidural analgesia through the same catheter.

Hormonal indexes of stress are reduced postoperatively in patients given epidural analgesia using a local anesthetic (e.g., 0.25% bupivacaine) such as after cholecystectomy. Yet even when pain is completely eliminated by this technique, these hormonal stress responses do not vanish ("Analgesia and the metabolic," 1985). Normally, a minimum of 3 or 4 days will elapse postoperatively before oral analgesia is feasible following operations on the biliary system, stomach or intestine, or vasculature in the upper abdomen.

In preparing the patient for any upper abdominal operation, choices of pain management to be reviewed with the patient include: intramuscular or subcutaneous injection of an opioid as needed, a"round-the-clock" schedule of injections (or continuous infusion of opioid) to be withheld in the event of side effects such as respiratory depression or nausea, intravenous PCA, or epidural analgesia in the manner described for postthoracotomy pain. Each of these approaches carries its own risks and benefits, which depend on the health care team's knowledge, expertise, and ability to recognize and treat side effects and correct inadequate pain relief. Other techniques have been used for post-cholecystectomy pain, such as interpleural catheters or supplemental, long-acting local anesthetic blocks of the lower intercostal nerves and celiac plexus. These lie outside the range of most current clinical practice.

Lower abdominal and perineal surgery (includes abdominal hysterectomy, cesarean section, hernia repair, episiotomy, urological and gynecological procedures, and hemorrhoidectomy).

The pain management plan for the patient undergoing lower abdominal or perineal surgery is based on the same principles as those for patients undergoing upper abdominal procedures. On the other hand, analgesia to control pain of active labor must be approached with special expertise and caution in light of side effects that may impair fetal well-being (e.g., fetal respiratory depression after maternal opioids or maternal hypotension after epidural local anesthetic). Suppression of pain and surgical stress responses is more complete with epidural local anesthesia after lower abdominal surgery than after upper abdominal operations (Kehlet, 1989b). Presumably this is because pathways such as phrenic or thoracic somatosensory afferents are less easily blocked by epidural anesthesia. Many obstetrical or urological procedures (e.g., cystoscopy) routinely are performed using spinal or epidural anesthesia, and the addition of low doses of opioid to a local spinal anesthetic appears to lengthen the duration of analgesia observed after the local anesthetic effect has subsided (Capogna, Celleno, Tagariello, and LoffredaMancinelli, 1988; Chawla, Arora, Saksena, and Gode, 1989; Hanson, Hanson, and Matousek. 1984; Pybus, D'Bras, Goulding, Liberman, and Torda, 1983; Reay, Semple, Macrae, MacKenzie, and Grant, 19891. Pain after procedures on the anus is particularly severe and requires adjunctive measures such as stool softeners, dietary manipulation, and local anesthetic suppositories for control. Again, the precautions already outlined concerning spinal opioid use and the necessity for close monitoring apply. Goals of the postoperative pain management plan should include early ambulation. For obstetric procedures, opioid doses should be adjusted so as to produce minimum maternal and fetal sedation. Alternatively, if an epidural catheter has been placed for infusion of local anesthetic to control labor pain or to provide anesthesia for cesarean section, a dilute solution of local anesthetic may be infused through this catheter to control postoperative pain with little risk of sedating the nursing infant.