THORAX (NON-CARDIAC) SURGERY

Thoracotomy

Type of Pain:
Thoracotomy produces nociceptive and neuropathic pain that is aggravated by respiration and coughing. Pain may be further exacerbated by the presence of chest tubes and drains.

Severity/Duration:
Thoracotomy pain is generally moderate to severe, lasting weeks. Patients may develop post-thoracotomy pain syndromes lasting months to years.

Interventions:

• There is good evidence that aggressive pain control in the form of epidural analgesia or neural blockade with local anesthesia following thoracic surgery improves pulmonary function, reduces morbidity, and reduces the length of stay in intensive care.



• Effective postoperative pain control may be achieved by delivering an opioid or a combination of an opioid and local anesthetic into the thoracic epidural space (Mahon et al., 1999; Miguel & Hubbell, 1993; Brichon et al., 1994). Mixing a local anesthetic with an opioid produces better and more prolonged analgesia, but randomized controlled trials indicate that there is a tendency toward more side effects when an opioid is added to a local anesthetic as compared to local anesthetic alone (Mahon et al., 1999). The addition of local anesthetics to epidural opioids allows a significant reduction in the total opioid required to produce equivalent analgesia (Burgess et al., 1994). However, reliance on local anesthetics alone to secure postoperative epidural analgesia in the thoracic region may be associated with hypotension due to sympathetic blockade. Epidural opioids may be delivered via either a lumbar or thoracic approach (Gaeta et al., 1995). Lumbar epidural opioids have been used successfully to provide analgesia but are less effective than thoracic administration. An example of a coordinated approach to postoperative analgesia following thoracic surgery is the placement of an epidural catheter prior to induction of anesthesia. This catheter may be used to deliver local anesthetic, either alone or mixed with an opioid for intraoperative analgesia. The catheter may then be left in place postoperatively for infusion of an analgesic solution containing either a local anesthetic, an opioid, or a combination of the two, delivered either as a continuous infusion or patient-controlled epidural analgesia. The patient is then switched to patient-controlled analgesia or oral analgesics if the epidural catheter ceases to function or is discontinued after several days.



• There is no significant difference between lumbar and thoracic epidural administration of the highly lipid-soluble opioids, fentanyl and sufentanil (Haak-van der Lely et al., 1994; Swenson et al., 1994). In addition, there is no significant difference between epidural and intravenous administration of these highly lipid-soluble opioids (Baxter et al., 1994; Sandler et al., 1992; Guinard et al., 1992).



• Preoperative initiation of a continuous local anesthetic epidural block has been associated with reduced long-term (at 6 months) post-thoracotomy pain (Obata et al., 1999).



• Paravertebral blocks performed as single shot or continuous techniques are also useful in providing postoperative analgesia following thoracic surgical procedures (Carabine et al., 1995). Continuous paravertebral blocks provide superior postoperative analgesia when compared to single shot techniques (Catala et al., 1996). Continuous paravertebral blocks are capable of providing equivalent or superior pain control when compared to epidural analgesia following thoracotomy (Richardson et al., 1999). Continuous paravertebral blocks are superior to interpleural blocks following thoracotomy (Richardson et al., 1995fF).



• Direct injection of a local anesthetic alone to block intercostal nerves has been performed as a means to provide postoperative analgesia and improve pulmonary function after thoracotomy. Since the analgesia from these blocks lasts only 6-12 hours, a single injection rarely suffices for the entire postoperative period. More prolonged relief can be obtained by performing cryoanalgesic blocks of the intercostal nerves (Bucerius et al., 2000). This may provide pain relief for several weeks. The brief duration of intercostal nerve blocks has been treated in some centers by administering interpleural local anesthetics. A catheter is placed between the parietal and visceral pleura, and a local anesthetic is injected at 4-6 hour intervals or infused continuously to produce continuous analgesia across several dermatomes (Barron et al., 1999; Raffin et al., 1994). Clinical use of this technique has not found widespread acceptance and it has been out of favor for many years (Gaeta et al., 1995; Solomon et al., 1980).



• Intrathecal administration of opioids has been used successfully to provide postoperative analgesia following thoracic surgical procedures. Intrathecal opiates may be used to provide postoperative analgesia following thoracotomy. This technique is associated with good analgesia at rest and a reduction in the need for opiates delivered via other routes during the first 24 hours. It may also be associated with a higher incidence of side effects when compared with epidural opioids or epidural local anesthetic and opioid combinations. The addition of intercostal nerve blocks to intrathecal opioids does not significantly improve postoperative pain control and has been associated with decreased pulmonary function after 24 hours (Liu et al., 1995).>



• Administration of opioids via oral, IV, IM, or IV PCA routes can be an effective means of providing primary postoperative pain control or as an adjunct to regional or neuraxial analgesic techniques. 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 the dose needed. In this context, IV PCA has resulted in incrementally improved analgesia, increased patient satisfaction, and tendency toward improved pulmonary function and earlier recovery or discharge.



• Drains and chest tubes inserted during surgery can cause intense irritation and pain at entry sites or deeper. The use of NSAIDs as an adjunct to other postoperative analgesics is beneficial for control of nonincisional pain following thoracotomy (Singh et al., 1997). Acetaminophen may be used as an adjunctive analgesic if an NSAID is contraindicated. These medications are rarely, if ever, sufficient to provide complete pain relief following thoracotomy.



• The use of TENS may serve as a useful adjuvant following minor thoracic surgical procedures.

Considerations:

• Pulmonary toilet is very important in ensuring a good outcome, so pain control is of paramount importance. Regional analgesic techniques provide better pulmonary toilet than IV PCA (Benzon et al., 1993).



• Opiates should be used cautiously in the setting of severe pulmonary disease due to the potential complication of respiratory depression. Therefore, in this group, regional analgesia may be strongly preferred (Benzon et al., 1993).

EVIDENCE TABLE