Anesth Analg 2003;96:1545-1546
© 2003 International Anesthesia Research Society
EDITORIAL
Epidural Insertion in Anesthetized Adults: Will Your Patients Thank You?
Richard W. Rosenquist, MD*, and
David J. Birnbach, MD
*University of Iowa College of Medicine, Iowa City, Iowa, and
University of Miami School of Medicine, Miami, Florida
Address correspondence and reprint requests to David J. Birnbach, MD, University of Miami School of Medicine, 1611 NW 12th Ave., Room C-301, Miami, FL 33136. Address e-mail to dbirnbach{at}Miami.edu
It has been 5 years since Drs. Bromage and Benumof (1) began a debate among anesthesiologists by reporting a closed-claim case of paraplegia after intracord injection during attempted epidural anesthesia under general anesthesia. These authors stated "any complaint of lancinating pain during epidural puncture may be caused by mechanical stimulation of a spinal root or the cord itself and that it is a clear signal to halt advance of the epidural needle immediately." Furthermore, they admonished against attempting epidural procedures above the termination of the cord in unconscious patients. After this editorial, many practitioners embraced the belief that accidental injury to the spinal cord during attempted epidural anesthesia is a potentially catastrophic complication that is avoidable if the patient is awake. Bromage and Benumof’s concern about pain during the procedure was echoed by Auroy et al. (2) when they reviewed serious complications during regional anesthesia (spinal, epidural and peripheral blocks). They stated "in all cases of radiculopathy after epidural anesthesia (n = 5) and peripheral blocks (n = 4), needle puncture was associated either with paresthesia during puncture (n = 19) or with pain during injections (n = 2)." In all cases, radiculopathy had the same topography as associated paresthesias. Controversy became more heated shortly thereafter, when an editorial by Krane et al. (3), supporting the use of regional techniques in anesthetized children, suggested that not all patients needed to be awake for placement of epidural catheters, including thoracic epidurals.
A new look at this controversy comes by way of a retrospective analysis by Horlocker et al. (4) of neurologic complications in 4298 thoracic surgical patients who underwent lumbar epidural catheter placement while under general anesthesia and published in this issue of Anesthesia & Analgesia. While on the surface this article might sway a practitioner to abandon the warnings of Bromage (5) that epidural catheter placement in the anesthetized patient is potentially dangerous, we suggest a closer look at these data before changing anesthetic practice.
In reviewing this subject, the following questions should be asked:
- Is this study large enough? Since the risk of cord or nerve root damage is small, a large number of patients need to be examined before seeing such a complication. A review of the serious nonfatal complications associated with 505,000 obstetric epidural blocks reported 38 cases of damage to a single nerve or nerve root (6). Only one of these was associated with a permanent neuropathy, perhaps because the patients were able to complain about pain during the procedure. These authors concluded that damage to a single spinal nerve "may occur during location of the extradural space or during insertion of the extradural catheter and is the commonest neurologic complication. Paresthesia with or without motor weakness is the presenting symptom and, while the majority of patients recover completely, a small number may be affected permanently." Based on the rarity of these complications, any study evaluating this outcome that examines too few patients results in too little discriminatory power. As Horlocker et al. state in their paper, due to inadequate numbers of evaluated patients, "the possibility of serious neurologic complication may still be as high as 0.08%." Other authors have quoted different statistics, yet all indicate to us that a larger series is needed. Aromaa et al. (7) reported the incidence of serious complications related to epidural anesthesia of 0.52:10,000. Auroy et al. (2) reported an incidence of neurologic injury related to epidural anesthesia of 2:10,000 with a 95% confidence interval of 0.4–3.6. Dahlgren et al. (8) reported 10 patients with persisting lesions after 9232 epidural anesthetics for an incidence of 10.8:10,000.
- Isn’t the complication limited to thoracic epidurals? The problems with this argument are: a) there is wide variation in the vertebral level at which the spinal cord terminates, ranging from T12 to L3–4 (9), b) the ability of anesthesiologists to correctly identify a lumbar interspace may be off as much as 4 interspaces (10), and c) there are significant changes that occur with age and disease in the lumbar spine and epidural space (11). Lumbar spinal stenosis is a common disease in older adults likely to undergo thoracotomy. Changes that occur in the development of lumbar spinal stenosis may alter the epidural space significantly and put all of the nerve roots at that level in a very compact bundle that is potentially at greater risk for mechanical trauma.
- If neuraxial blockade in anesthetized children is acceptable, why not in adults? A decade of epidural blocks inserted in anesthetized pediatric patients without evidence of neurologic damage shows the safety of this approach, although the incidence of neurologic complications in pediatric patients is unknown and the relative numbers of these blocks in pediatric patients is small compared to adults. In light of this, extrapolation of pediatric data to adult practice is not warranted and offers no reassurance.
- Is retrospective review of data from this database complete enough to have identified all cases of neurologic complications? Horlocker’s study was performed at the Mayo Clinic, and one must wonder if the absence of post operative neurologic consultation at that large referral center (that many patients travel to for high end consultation or surgical care) rules out the presence of postoperative complaints that may have been dealt with by a local internist or neurologist after the patient returned home from their surgical procedure.
- What exactly are the benefits to performing these blocks under general anesthesia? Is an epidural so painful as to preclude its use unless general anesthesia can be administered first? More than a million lumbar epidurals are performed on laboring women each year who receive no sedation or anesthesia. If this is not problematic, why can’t patients undergoing other surgical procedures tolerate an epidural placement? Is there any reason that a patient for thoracic surgery can’t handle a minimal level of momentary discomfort associated with epidural placement after administration of an appropriate amount of sedation and local anesthetic to decrease anxiety and discomfort? If time, rather than patient comfort is the issue, the question should be why not maximize efficiency by performing blocks before hand in a preoperative holding area?
- If a patient who receives a neuraxial block under general anesthesia develops a neurologic complication regardless of cause and sues, is the practice defensible in our current medicolegal climate?
Despite these lingering questions, we applaud the courage of Horlocker et al. who have attempted to answer an important clinical question. The problem, however, is that despite their stated safety record, there are not nearly enough data to support the routine initiation of epidural blocks in anesthetized adult patients. Will this always be the case? Perhaps not. If and when more safety data are available, this point should be revisited. For the time being however, we believe that the risk-benefit ratio does not support this practice and that epidurals should be placed in awake or mildly sedated patients capable of providing feedback to the individual placing the block. Although this has not completely prevented neurologic complications, the clear association of pain during placement or injection and the subsequent injury speak for the utility of feedback from the patient in preventing further injury if the warning is heeded.
References
- Bromage PR, Benumof JL. Paraplegia following intracord injection during attempted epidural anesthesia under general anesthesia. Reg Anesth Pain Med 1998; 23: 104–7.[ISI][Medline]
- Auroy Y, Narchi P, Messiah A, et al. Serious complications related to regional anesthesia: results of a prospective survey in France. Anesthesiology 1997; 87: 479–86.[ISI][Medline]
- Krane EK, Dalens BJ, Murat I, Murrell D. The safety of epidurals placed during general anesthesia. Reg Anesth Pain Med 1998; 23: 433–8.[ISI][Medline]
- Horlocker TT, Abel MD, Messick JM, Schroeder DR. Small risk of serious neurologic complications related to lumbar epidural catheter placement in anesthetized patients. Anesth Analg 2003; 96: 1547–52.[Abstract/Free Full Text]
- Bromage PR. Epidural analgesia. Philadelphia: WB Saunders, 1978: 638–41.
- Scott DB, Hibbard BM. Serious non-fatal complications associated with extradural block in obstetric practice. Br J Anaesth 1990; 64: 537–41.[Abstract/Free Full Text]
- Aromaa U, Lahdensuu M, Cozanitis DA. Severe complications associated with epidural and spinal anaesthesias in Finland 1987–1993. A study based on patient insurance claims Acta Anaesthesiol Scand 1997; 41: 445–52.[ISI][Medline]
- Dahlgren N, Tornebrandt K. Neurological complications after anaesthesia. A follow-up of 18, 000 spinal and epidural anaesthetics performed over three years Acta Anaesthesiol Scand 1995; 39: 872–80.[ISI][Medline]
- Reimann AF, Anson BJ. Vertebral level of termination of the spinal cord with report of a case of sacral cord. Anat Rec 1944; 88: 127–38.
- Broadbent CR, Maxwell WB, Ferrie R et al. Ability of anaesthetists to identify a marked lumbar interspace. Anaesthesia 2000; 55: 1122–6.[ISI][Medline]
- Hogan QH. Epidural anatomy examined by cryomicrotome section: influence of age, vertebral level and disease Reg Anesth 1996; 21: 395–406.[ISI][Medline]
Accepted for publication March 10, 2003.
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