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Chest and Chest Wall Surgery

Operative sites within the thorax include the heart, esophagus, and lungs and somatically innervated structures such as the ribs, superficial chest wall, and breast. Preexisting disease of these organs (e.g., chronic obstructive pulmonary disease) or prior medical treatment (e.g., chemotherapy) are common. They contribute to postoperative morbidity through a variety of mechanisms, such as decreased pulmonary reserve. Drains and chest tubes can cause intense irritation and pain at entry sites or deeper. For this reason, NSAIDs such as indomethacin in suppository form are useful to reduce inflammation although they are rarely enough for complete pain relief and indeed are not approved by the Food and Drug Administration as simple analgesics.

Good evidence exists that aggressive pain control in the form of epidural analgesia or neural blockade with local anesthetics after thoracic surgery improves pulmonary function; however, at present there is insufficient evidence from randomized controlled trials (RCTs) to conclude that these fonns of aggressive pain control after thoracic surgery hasten walking or reduce morbidity and length of hospital stay (Guideline Report, in press; Hasenbos, van Egmond, Gielen, and Crul, 1987; Kaplan, Miller, and Gallagher, 1975; Sabanthan, Mearns, Bickford Smith, Eng, Berrisford, Bibby, and Majid, 1990; Shulman, Sandler, Bradley, Young, and Brebner, 1984).

The greatest beneficial effects result from administration of opioids or a combination of opioid and local anesthetic in the thoracic epidural space. Reliance on a local anesthetic alone to secure postoperative epidural analgesia in the thoracic region carries possible side effects such a,; hypotension due to sympathetic blockade. Respiratory impairment because of somatic nerve block is another potential problem; therefore, intercostal nerve blocks are generally undesirable unless an opioid is contraindicated. Mixing a local anesthetic with an opioid produces better and more prolonged analgesia, but RCTs indicate that there is a tendency toward more side effects when an opioid is added to a local anesthetic, compared with the local anesthetic alone (Guideline Report, in press; Capogna, Celleno, Tagariello, and Loffreda-Mancinelli, 1988; Pybus, D'Bras, Goulding, Liberman, and Torda, 1983). An example of a coordinated approach to postoperative analgesia is the placement of an epidural catheter prior to induction of anesthesia, which is used to deliver local anesthesia, either alone or mixed with an opioid for intraoperative analgesia, and then left in place postoperatively for infusion of a dilute analgesic. As previously emphasized, monitoring and care of patients with epidural catheters and assessment of the optimal time for switching to oral analgesia are best accomplished by a specially trained team.

Direct injection of local anesthetics alone to block intercostal nerves has been done for years as a means to provide postoperative analgesia and improved pulmonary function after thoracotomy. Unfortunately, such analgesia lasts only 6 to 12 hours, so that a single injection rarely suffices for the entire postoperative period. A clinician can overcome the brief duration of intercostal anesthesia by administering interpleural local anesthetics. To accomplish this, a catheter is placed between the parietal and visceral pleura, and anesthetic is injected at 4- to 6-hour intervals or infused continuously to produce continuous analgesia across several dermatomes (Scott, Mogensen, Bigler, and Kehlet, 1989). As in all invasive techniques, this method requires skill in drug titration and vigilance for management of side effects such as pneumothorax.

The use of opioids to reduce postoperative pain after thoracotomy is well documented. Because of potential side effects, clinicians have tried to optimize delivery and closely match dose to need. In this context, PCA has resulted in incrementally improved analgesia, increased patient satisfaction, and tendencies towards improved pulmonary function and earlier recovery or discharge (Guideline Report, in press; Eisenach, Grice, and Dewan, 1988; Jackson, 1989; McGrath, Thurston, Wright, Preshaw, and Fermin, 1989; Wasylak, Abbott, English, and Jeans, 1990). One strategy to manage pain after thoracotomy is to deliver epidural analgesia to prevent pain and then switch to patient controlled intravenous analgesia if the epidural catheter ceases to function or is discontinued after several days on the ward.

A typical prescription for intravenous PCA in this setting relies first on a series of "loading" doses: for example, 3-5 mg of morphine, repeated every 5 minutes until the initial postoperative pain diminishes. A low-dose basal infusion at night (e.g., 0.5-1.0 mg/hr) allows uninterrupted sleep for the patient. On-demand doses typically add 0.5-1.5 mg of morphine every 6 minutes. PCA doses of opioid are valuable to supplement analgesia during respiratory therapy or ambulation, even after the patient is taking oral analgesics and especially while chest tubes are in place. The transition from intravenous PCA to oral opioids is accomplished as described above (p. 201. If adequate opioid analgesia yields undesired side effects, or if pain is not severe (e.g., when chest tubes are no longer in place), the patient can switch directly from epidural to oral analgesia using a combination of opioid and NSAID. Many opioid analgesics or mixtures are available in liquid form and are useful for patients unable to swallow tablets or capsules (e.g., after esophageal surgery).

Cardiac surgery.

Most cardiac operations involve a median sternotomy and anesthetic induction using high doses of opioids (morphine at 1 mg/lcg or another opioid at an equivalent dose). Because somatic nerves are not divided by the surgical incision, postoperative pain is usually less than after conventional thoracotomy, even when lower doses of opioids are given during surgery. For procedures that use intercostal incisions, such as implantation of automatic defibrillatory devices, methods of pain control need not differ from those of other thoracic operations. Close observation is essential to distinguish postoperative pain originating in the chest wall and pleura from cardiac pain, which may signal myocardial ischemia due to a tachyrhythmia or threatened infarction from inadequate revascularization.