LETTERS TO THE EDITOR: Letters & Announcements
To the Editor:
Toker et al. (1) describe the case of a defective epidural catheter, through which injection of medication was impossible. However, we would like to draw attention to several points. The authors write that the catheter was inserted following induction of general anesthesia. The patient was a 56-yr-old man undergoing gastrectomy. We noticed the following:
* The epidural catheter was inserted at the level of L4/5 and was advanced 4 cm into the epidural space. We believe this level is not adequate for treating peri- or postoperative pain following gastrectomy. For an epigastric surgical procedure, the catheter should have been placed at a thoracic level (2) to avoid large doses of medication.
* As described in the letter, the epidural catheter was inserted during general anesthesia. We think this fact is especially problematic because of the inability to test whether the catheter has been erroneously placed in the subdural space. Accidental nerve damage can be recognized during insertion of an epidural catheter while the patient is awake. General anesthesia precludes this, since the patient cannot say whether he or she has pain or dysesthesia. General anesthesia also precludes testing the catheter position with a probatory dose. There are multiple publications referring to this problem (3–5). Since in this case the epidural catheter was presumably placed for postoperative pain management, large amounts of local anesthetics or opioids would be necessary to attain adequate thoracic pain control. Such high doses would be problematic if the catheter has been accidentally placed in the subdural space, causing possible spinal anesthesia (following local anesthetics) or respiratory depression (following opioids). When both epidural and general anesthesia are necessary, a probatory dose of a local anesthetic should be given while the patient is still awake, prior to the first analgesic dose, in order to identify accidental subdural placement. Merely aspirating cerebrospinal fluid is not sufficient. If the patient has been under general anesthesia and medication cannot be administered epidurally, the patient may become subjected to an analgesic gap because it is necessary to wait until the patient is vigilant enough to respond verbally to the test dose. During an analgesic gap pain management is inadequate. A study in England revealed that in 60% of the 192 clinics questioned thoracic epidural catheters were placed during general anesthesia (6). Even if it is common in other countries to place a thoracic epidural catheter under general anesthesia, it is not a recommended procedure in Germany (7).
The erroneous catheter placement can often be recognized with a placement prior to induction of general anesthesia, thus preventing complications. In the case described here, it would have also been possible to identify the faulty catheter by administering a test dose before general anesthesia. Then the catheter could have been removed and a new one placed before induction.
Peter Lierz, MD
Anja Heinatz, MD
Burkhard Gustorff, MD, DEAA
Peter Felleiter, MD
1. Toker K, Gürkan Y, Keser M. A faulty epidural catheter. Anesth Analg 2002; 94: 1371–2.
2. Wajima Z, Shitara T, Ishikawa G, et al. Analgesia after upper abdominal surgery with extradural buprenorphine with lidocaine. Can J Anesth 1998; 45: 28–33.
3. Okuyama A, Saito Y, Amenomori H, et al. Subdural catheterisation uncovered by severe hypotension during epidural plus general anesthesia. Masui 1995; 44: 1373–6.
4. Bromage PR, Benumof JL. Paraplegia following intracord injection during attempted epidural anesthesia under general anesthesia. Reg Anesth Pain Med 1998; 23: 104–7.
5. Krane EJ, Dalens BJ, Murat, Murell D. The safety of epidurals placed during general anesthesia. Reg Anesth Pain Med 1998; 23: 433–8.
6. Romer HC, Russell GN. A survey of the practice of thoracic epidural analgesia in the United Kingdom. Anaesthesia 1998; 53: 1016–22.
7. Wulf H. Epidural catheterisation in general anesthesia? Anaesthesist 1999; 48: 183–4.