Dilaudid

QUESTION: My patient has a thoracic epidural catheter for pain control after a thoracotomy. Does this catheter placement require different drugs than a lumbar epidural catheter?

ANSWER: No, the same medications infused through a lumbar epidural catheter can be used with a thoracic epidural catheter. Most epidurals contain a preservative-free mixture of an opioid, such as fentanyl, morphine, or hydromorphone HCl (Dilaudid), and a local anesthetic such as bupivacaine or ropivacaine. But because it's placed as close to the level of the incision as possible, a thoracic epidural catheter can deliver targeted pain relief with a very low continuous infusion rate. This increases the patient's ability to cough and breathe deeply in the immediate postoperative period.

Thoracic epidural catheters used as patient-controlled epidural analgesia (PCEA) may provide excellent pain relief with a low continuous infusion rate and small bolus doses, compared with a lumbar epidural catheter and PCEA pump. Thoracic epidural catheters also let the patient move more easily and clear secretions more effectively soon after surgery. However, thoracic epidural catheters are more difficult for the anesthesiologist to place because of the narrowing of the spinal column and proximity of the dura. This increases the risk of a dural tear and leak.

Thoracic epidural catheters are indicated to manage pain in patients who've had a thoracotomy, abdominal aortic aneurysm repair, or abdominal surgery with a large incision. Here's what you need to know when caring for a patient with a thoracic catheter.

Where to place the catheter

The anesthesiologist determines catheter placement based on the planned location of the surgical incision and a dermatome chart. He places the catheter at the appropriate level for opioid medication to be transferred to spinal receptor sites, where it's taken up by epidural vessels and the receptor sites in the central nervous system. For example, the catheter would be placed at T5 to T7 for a thoracotomy and at T8 to T10 for abdominal surgery. The local anesthetic in the epidural solution bathes the nerve roots at the insertion level, providing additional pain control.

If the anesthesiologist can't place the catheter at the desired level because of patient factors (such as a bony growth from arthritis), he'll place it as close to that level as possible.

High thoracic catheter placement (T4 to T5) carries the risk that local anesthetic will migrate upward, affecting the patient's diaphragm and respiratory function. Also, if the catheter points toward the patient's head rather than toward his feet, the medication may infuse to a higher level than intended.

Using higher concentrations of local anesthetic concentration in some situations could potentially pose more risk of undesired areas of blockade, affecting respiratory function. This potential raises concerns about using thoracic epidural catheters in patients with compromised respiratory function. But a recent study of patients with severe chronic obstructive pulmonary disease found that a bupivacaine concentration as high as 0.25% didn't impair ventilatory mechanics or inspiratory muscle strength.

By knowing the level of catheter placement and where the pain relief is supposed to occur, you'll understand which adverse reactions to watch for and be able to help your patient manage her pain better. For example, the top of the shoulder is in the cervical dermatome distribution and isn't covered by a thoracic epidural catheter. If the patient reports shoulder pain, she'll need an additional analgesic such as ketorolac to relieve pain in this area.

Your role

Postoperative assessment of a patient with a thoracic epidural catheter includes assessing her pain control and sensory motor function (such as hand or arm numbness), and monitoring for such adverse reactions as respiratory depression.

SELECTED REFERENCES

Gruber, E., et al.: 'The Effects of Thoracic Epidural Analgesia with Bupivacaine 0.25% on Ventilatory Mechanics in Patients with Severe Chronic Obstructive Disease," Anesthesia and Analgesia. 92(4):1015-1019, April 2001.

Hahn, M., et al.: Regional Anesthesia: An Atlas of Anatomy and Techniques. St. Louis, Mo., Mosby, Inc., 1996.

Ochroch, E., et al.: "Long-Term Pain and Activity during Recovery from Major Thoracotomy Using Epidural Analgesia," Anesthesiology. 97(5):1234-1244, November 2002.

Peng, P., and Sandler, A.: "A Review of the Use of Femanyl Analgesia in the Management of Acute Pain in Adults," Anesthesiology. 90(2):576-599, February 1999.

BY YVONNE D'ARCY, CRNP, CNS, MS

Yvonne D'Arcy is a nurse practitioner in pain management and the pain and palliative care outcomes manager at Suburban Hospital in Bethesda, Md.

Copyright Springhouse Corporation Sep 2004
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