Regional blockade and pre-existing medical conditions

THE IMMUNCOMPROMISED OR SEPTIC PATIENT
INFECTIOUS COMPLICATIONS OF REGIONAL ANESTHESIA

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T Horlocker
Mayo Clinic, Rouchester, MN, United States

Bacterial infection of the neuraxis may present as meningitis or cord compression secondary to abscess formation. The infectious source can be exogenous due to contaminated equipment or medication or endogenous secondary to a bacterial source in the patient seeding to the remote site of needle or catheter insertion. In addition, indwelling catheters may be colonized from a superficial site and subsequently serve as a wick for spread of infection from the skin to the epidural or intrathecal space. An alternative mechanism may be contamination of the epidural or intrathecal space with viridans streptoccoci from the operator's buccal mucosa (Schneeberger, 1996; Trautman, 2002; Couzigou, 2003). Schneeberger et al (Schneeberger, 1996) recently reported 4 cases of iatrogenic meningitis following spinal anesthesia occurring over a 4-year period. The patients typically presented 24 hours postoperatively with a severe headache (2 received an epidural blood patch). All cases involved the same anesthesiologist, who had a history of recurrent pharyngitis and did not wear a mask during the procedure. As a result of this cluster of cases, infection control measures, including the wearing of face masks, were introduced. While there is some evidence that face masks reduce the spread of viridans streptococci, it has not been shown that face masks will reduce the incidence of neuraxial infection. There are currently no universal guidelines or recommendations for their use during regional anesthetic procedures.

Although individual cases have been reported in the literature, serious neuraxial infections such as arachnoiditis, meningitis, and abscess following spinal or epidural anesthesia are rare. In a combined series of more than 65,000 spinal anesthetics, there were only 3 cases of meningitis. A similar review of approximately 50,000 epidural anesthetics failed to disclose a single epidural or intrathecal infection (Kane, 1981). Aromaa et al. (Aromaa, 1997) reported 8 cases of bacterial infections in patients undergoing 170,000 epidural and 550,000 spinal anesthetics (1.1:100,000 blocks) from a Finnish database. More recently, Moen et al (Moen, 2004) reviewed the Swedish experience from 1990-1999 and reported a low incidence of epidural abscess, but an alarming association of post-spinal block meningitis with alpha-hemolytic streptococcal cultures, suggesting a nosocomial origin.

Few data suggest that spinal or epidural anesthesia during bacteremia is a risk factor for infection of the neuraxis. Although the authors of the previous studies did not report how many patients were febrile during administration of the spinal or epidural anesthetic, a significant number of the patients included in these studies underwent obstetric or urologic procedures. Therefore, it is likely that some patients had bacteremia after (and perhaps during) needle or catheter placement. Despite the apparent low risk of central nervous system infection following regional anesthesia, some anesthesiologists have long considered sepsis to be a relative contraindication to the administration of spinal or epidural anesthesia. This impression is based mainly on anecdotal reports and conflicting laboratory and clinical investigations.

Meningitis after Dural Puncture

Dural puncture has long been considered a risk factor in the pathogenesis of meningitis. Exactly how bacteria cross from the blood stream into the spinal fluid is unknown. The presumed mechanisms include introduction of blood into the intrathecal space during needle placement and disruption of the protection provided by the blood-brain barrier. However, lumbar puncture is often performed in patients with fever or infection of unknown origin. If dural puncture during bacteremia results in meningitis, definite clinical data should exist. In fact, clinical studies are few, and often are antiquated.

Initial laboratory and clinical investigations were performed more than 80 years ago. Weed et al. (Weed, 1919) found that lumbar or cisternal puncture performed during septicemia in multiple animal models (produced by IV injection of a gram-negative bacillus) invariably resulted in a fatal meningitis. Wegeforth at al (Wegeforth, 1919) reported their clinical observations on 93 patients suspected of having meningitis who received a diagnostic lumbar puncture. Blood cultures were taken simultaneously. The diagnosis was confirmed in 38 patients. The remaining 55 patients had normal cerebrospinal fluid (CSF). However, 6 of these 55 patients were bacteremic at the time of lumbar puncture. Five of the 6 bacteremic patients subsequently developed meningitis. It was implied, but not stated, that patients with both sterile blood and CSF cultures did not develop meningitis. Unfortunately, these lumbar punctures were performed during 2 epidemics of meningitis that occurred at a military installation, and it is possible that some (or all) of these patients may have developed meningitis without lumbar puncture. These 2 historical studies provided support for the claim that lumbar puncture during bacteremia was a risk factor for meningitis.

In a recent study similar to that by Weed et al., Carp and Bailey (Carp, 1992) investigated the association between meningitis and dural puncture in bacteremic rats. Twelve of 40 rats subjected to cisternal puncture with a 26-gauge needle during Escherichia coli bacteremia subsequently developed meningitis. In addition, bacteremic animals not undergoing dural puncture and animals undergoing dural puncture in the absence of bacteremia did not develop meningitis. Meningitis occurred only in animals with a blood culture result of greater than 50 colony forming units/mL at the time of dural puncture. Treatment of a group of bacteremic rats with a single dose of gentamicin immediately prior to cisternal puncture apparently eliminated the risk of meningitis, as none of these animals developed infection.

Meningitis after Dural Puncture

* Significant association (p<0.001)

Spontaneous meningitis = concurrent bacteremia and meningitis (without a preceding lumbar puncture). Lumbar puncture-induced meningitis = positive blood culture with sterile CSF on initial exam; subsequent positive CSF culture (same organism present in blood).

From: Horlocker TT, Wedel DJ. Regional anesthesia and infection. In: Finucane BT, ed. Complications of Regional Anesthesia. Philadelphia, PA: Saunders 1999:170-183.

This study shows that dural puncture in the presence of bacteremia is associated with the development of meningitis in rats and that antibiotic treatment before dural puncture reduces this risk. Unfortunately, this study did not include a group of animals that were treated with antibiotics after dural puncture. Because many surgeons defer antibiotic therapy until after cultures are obtained, the actual clinical scenario remains unstudied. There are several other limitations to this study. While E. coli is a common cause of bacteremia, it is an uncommon cause of meningitis. In addition, the authors knew the sensitivity to the bacteria injected, allowing for appropriate antibiotic coverage. The authors also performed a cisternal puncture (rather than lumbar puncture) and used a 26-gauge needle, producing a relatively large dural defect in the rat compared with dural puncture with spinal needles in humans. Finally, no local anesthetic was injected. Local anesthetic solutions are typically bacteriostatic, which may reduce the risk of meningitis in normal clinical settings. These results may not apply to administration of epidural anesthesia in the febrile patient (which involves placement of an indwelling catheter).

Epidural Abscess after Epidural Anesthesia

Several relevant studies have specifically examined the risk of epidural abscess in patients receiving epidural anesthesia and/or analgesia. Bader et al. (Bader, 1992) investigated the use of regional anesthesia in women with chorioamnionitis. Three hundred nineteen women were identified from a total of 10,047 deliveries. Of the 319 women, 100 had blood cultures taken on the day of delivery. Eight of these had blood cultures consistent with bacteremia. Two hundred ninety-three of the 319 patients received a regional anesthetic; in 43 patients antibiotics were administered before needle or catheter placement. No patient in the study, including those with documented bacteremias, had infectious complications. In addition, mean temperatures and leukocyte counts in patients who received blood cultures showed no significant differences between bacteremic and nonbacteremic groups. These authors continue to administer spinal and epidural anesthesia in patients with suspected chorioamnionitis because they believe the potential benefits of regional anesthesia outweigh the theoretical risk of infectious complications.

Infectious Complications Following Regional Anesthesia

Adapted from: Horlocker TT, Wedel DJ. Regional anesthesia and infection. In: Finucane BT, ed. Complications of Regional Anesthesia. Philadelphia, PA., Saunders 1999:170-183.

Strafford et al. (Strafford, 1995) reviewed 1,620 pediatric patients who received epidural analgesia for postoperative pain relief. Epidural catheters were left indwelling for a median of 2 days (range, 0 to 8 days). No patient developed an epidural abscess. One patient with osteosarcoma metastatic to spine, chest wall, and lungs became febrile after 10 days of epidural catheterization. When the catheter was removed, culture demonstrated candidal contamination. A second thoracic epidural catheter was placed 4 days later to provide analgesia. Two weeks later, she developed an acute sensory and motor block at T2. Magnetic resonance images (MRI) showed an epidural fluid collection; an emergent laminectomy was performed. A large amount of necrotic tumor as well as fluid containing C. tropicalis was present in the epidural space. Her neurologic deficits resolved postoperatively. Three additional patients with chronic pain syndromes were evaluated for epidural infection; all were negative. The authors concluded that for terminally ill patients, the risk of infection with long-term epidural catheterization is acceptable, but recommended careful monitoring to avoid serious neurologic sequelae

The safety of epidural analgesia in 75 patients admitted to the intensive care unit was prospectively evaluated by Darchy et al. (Darchy, 1996) There were no epidural abscesses. However, 5 of 9 patients with positive cultures of the catheter insertion site also had positive catheter tip cultures (epidural catheter infection); Staphylococcus epidermidis was the most commonly cultured microorganism. Local infection of the catheter site was treated with catheter removal, but antibiotic therapy was not specifically prescribed. Concomitant infection at other sites, antibiotic prophylaxis, and duration of epidural analgesia were not risk factors for epidural analgesia-related infections. The authors noted that the presence of both erythema and local discharge is a strong predictor of local and epidural catheter infection.

Chronic epidural catheterization in cancer patients is also a potential risk for epidural infection. Du Pen et al. (Du Pen, 1990) studied 350 patients in whom permanent (tunneled) epidural catheters were placed. The authors examined 3 areas of the catheter track for evidence of infection: exit site, superficial catheter track, and epidural space. The rate of epidural and deep track catheter-related infections was one in every 1,702 days of catheter use in the 19 patients who developed deep track or epidural infections. (Four of the 19 patients had both deep track and epidural involvement.) Bacteria cultured were most frequently skin flora. All 19 patients with deep infections were treated with catheter removal and antibiotics; none required surgical decompression or debridement. Catheters were replaced in 15 of the 19 patients who requested them after treatment with no recurrent infections. The authors state recommendations similar to Strafford et al.; long-term epidural catheterization is safe when patients are carefully monitored for signs of infection and receive prompt treatment when the diagnosis is established.

Epidural anesthesia and analgesia in a patient with a known systemic or localized infection remain controversial. Jakobsen et al. (Jakobsen, 1995) retrospectively reviewed the records of 69 patients with abscesses or wound infections who underwent epidural catheter placement for surgical debridement over a 7-year period. Several patients had more than one catheter inserted. Catheters were left indwelling for a mean of 9 days. On 12 occasions (8 patients), the catheter was removed because of local infection. None of the patients had signs or symptoms of neuraxial infection. The authors concluded that epidural anesthesia is relatively safe for patients requiring repeated surgical treatment of localized infection. In contrast, Bengtsson et al. (Bengtsson, 1997) reported 3 epidural catheter-related infections in patients with cutaneous wounds over a 4-year period. All patients were treated with antibiotic therapy; 1 patient underwent transcutaneous drainage of an epidural abscess. However, there were no neurologic deficits. It is difficult to determine the actual risk of epidural abscess in patients with chronic localized infections who undergo epidural catheter placement because of the small number of patients studied and the rarity of this complication. Therefore, the clinician must maintain vigilance in neurologic monitoring to ensure early recognition and treatment.

These results are contrasted by those of a one year survey in Denmark, in which the incidence of spinal epidural abscess following epidural analgesia was 1 in 1930 catheters and the likelihood of persisting deficits was 1 in 4343 catheters (Wang, 1999)! The disparity between these results and those previously published cannot be easily explained, although the mean period of epidural catheterization was 11 days, no prophylactic antibiotics were administered, and concomitant use of thromboprophylaxis may have lead to epidural hematomas (which were subsequently infected).

Herpes Simplex Virus

Herpes simplex virus type 2 (HSV-2) infection is an incurable, recurrent disease characterized by asymptomatic periods alternating with recrudescence of genital lesions. The primary infection is associated with viremia and can be accompanied by a variety of symptoms, including fever, headache, and rarely aseptic meningitis. In contrast, recurrent or secondary infections present as genital lesions without evidence of viremia. When obstetric patients present for delivery with evidence of active HSV-2 infection, cesarean delivery is recommended to avoid exposing the neonate to the virus during vaginal delivery. Neuraxial block in these patients is controversial because of the theoretical potential of introducing the virus into the central nervous system (CNS). However, there are little data to support these concerns.

Bader et al (Bader, 1990) reviewed the management of 169 parturients with HSV-2 infections; five of which were primary infections. Although general anesthesia was administered to 59 patients, the remaining 110 patients received spinal or epidural techniques. One patient with primary HSV-2 infection developed transient unilateral leg weakness after bupivacaine spinal anesthesia. The authors concluded that neuraxial block was safe in cases of secondary infection. Additional investigations support these recommendations, although the total number of patients studied is too limited to make a definitive assessment (Crosby, 1989; Ramanathan, 1986). In addition, because the risk of neurologic complications in patients undergoing neuraxial block in the presence of primary infection remains unknown, a conservative approach is recommended.

SV type 1, the infectious agent of oral herpes, rarely causes genital lesions. However, recurrent HSV-1 infection has been described in parturients receiving intrathecal and epidural opioids (Crone, 1990). The postnatal association is controversial since other factors, including emotional or physical stress, have been implicated as causes of recurrent HSV-1 infection.

Human Immunodeficiency Virus

The risk of performing neuraxial block in patients infected with human immunodeficiency virus (HIV) is largely undetermined. Approximately 40% of patients with the diagnosis of acquired immunodeficiency syndrome (AIDS) have clinical signs of neuropathy, and 70% to 80% have neuropathic changes present at autopsy. Because the virus infects the CNS early in the disease, it is unlikely that neuraxial block would result in new CNS transmission. However, the neurologic symptoms associated with HIV infection such as aseptic meningitis, headache, and polyneuropathy would be indistinguishable from those related to regional technique. Hughes et al. (Hughes, 1995). reported safe administration of neuraxial block to 18 HIV-infected parturients. However, the patients were relatively healthy and in the early stage of their disease. Uncomplicated placement of an epidural blood patch for treatment of postdural puncture headache in 9 HIV-positive patients has also been described (Tom, 1992). A clear understanding of the association of CNS symptoms with HIV infection is important to interpret postblock (or postblood patch) neurologic findings.

Infectious Complications of Peripheral Regional Techniques

The more frequent use of catheters for peripheral nerve blockade, often for prolonged periods, might be expected to increase the risk of infectious complications; however, few data are available to support this theoretical assumption. Auroy et al. (Auroy, 1997) reported no infectious complications in 21,278 peripheral nerve blocks. This low incidence is supported by Borgeat et al. (Borgeat, 2001) report of no complications in 521 patients undergoing interscalene nerve blockade and the report by Berman et al (Berman, 2003) report of one superficial infection treated with catheter removal and antibiotics, in 405 continuous axillary catheters receiving local anesthetic infusions.

Two studies look more specifically at the infectious risk in continuous peripheral nerve blocks. Bernard et al (Bernard, 2002) prospectively studied 1416 patients in ten centers undergoing continuous peripheral nerve blocks for orthopedic procedures. A total of 969 (68%) of catheters were cultured when removed, and patients were actively monitored for signs of localized infection or sepsis. A positive bacterial colonization was found in 278 catheters (28.7%), most commonly staphylococcus epidermidis (61%). Only 3% of patients had local signs of infection, and only 44% of these catheters had positive colonization. There was no correlation between colonization and the presence of fever. Risk factors in this study were admission to an intensive care unit, male gender, catheter duration exceeding 48 hours and lack of antibiotic prophylaxis. The second study by Cuvillon et al (Cuvillon, 2001) investigated the incidence of infectious complications in 211 continuous femoral catheters. Colonization of the 208 catheters examined after 48 hours showed a rate of 57% with the most common organism again being staphylococcus epidermidis (71%). Echography was performed in each instance of positive catheter colonization. No cellulitis or abscess was noted, however three transitory bacteremias were attributed to the presence of the femoral catheters. There were no long-term sequelae due to infectious causes.

Anesthetic Management of the Infected or Febrile Patient

In summary, several clinical and laboratory studies have suggested an association between dural puncture during bacteremia and meningitis. The data are equivocal, however. The clinical studies are limited to pediatric patients who are historically at high risk for meningitis. Many of the original animal studies used bacterial counts that were far in excess of those noted in humans in early sepsis, making CNS contamination more likely. Despite these conflicting results, it is generally recommended that except in the most extraordinary circumstances, neuraxial block should not be performed in patients with untreated bacteremia.

Patients with evidence of systemic infection may safely undergo spinal anesthesia if antibiotic therapy is initiated before dural puncture and the patient has responded to therapy, such as a decrease in fever. Placement of an indwelling epidural (or intrathecal) catheter in this group of patients remains controversial; patients should be carefully selected and monitored for evidence of epidural infection. Spinal anesthesia may be safely performed in patients at risk for low-grade transient bacteremia after dural puncture. Once again, little information exists concerning the risk of epidural anesthesia in patients suspected of developing an intraoperative transient bacteremia (such as during a urologic procedure). However, short-term epidural catheterization is most likely safe.

All patients with an established local or systemic infection should be considered at risk for developing infection of the CNS. A delay in diagnosis and treatment of even a few hours significantly worsens neurologic outcome. Bacterial meningitis is a medical emergency. Mortality is approximately 30%, even with antibiotic therapy. Meningitis presents most often with fever, severe headache, altered level of consciousness, and meningismus. The diagnosis is confirmed with a lumbar puncture. Lumbar puncture should not be performed if spinal abscess is suspected, because contamination of the intrathecal space may result. CSF examination in the patient with meningitis reveals leukocytosis, a glucose level of less that 30 mg/dL, and a protein level greater than 150 mg/dL.

The clinical course of epidural abscess progresses from spinal ache and root pain, to weakness (including bowel and bladder symptoms), and eventually paralysis. The initial back pain and radicular symptoms may remain stable for hours to weeks. However, the onset of weakness often progresses to complete paralysis within 24 hours. Although the diagnosis was historically made with myelogram, radiologic examination such as computed tomography scan, or preferably MRI, is currently recommended. A combination of antibiotics and surgical drainage remains the treatment of choice.

As with spinal hematoma, neurologic recovery is dependent on the duration of the deficit and the severity of neurologic impairment before treatment.

Infectious complications following peripheral nerve blocks are rare, even when catheter techniques are used. Intuitively, the similar precautions should be taken regarding skin preparation and dressing changes as are recommended for central neuraxial procedures. Prophylactic antibiotics may be protective, but data are not available to support this concept. If an infection does occur, removal of the catheter followed by appropriate antibacterial treatment is recommended. Use of echography to define the presence and extent of the infection may be helpful.

Time of Presentation
Saturday 13 May 2006 - 1330-1500

References

1. Aromaa U, Lahdensuu M, Cozanitis DA. Severe complications associated with epidural and spinal anaesthetics in Finland 1987-1993. A study based on patient insurance claims. Acta Anaesthesiol Scand 1997;41:445-52.
2. 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.
3. Bader AM, Camann WR, Datta S. Anesthesia for cesarean delivery in patients with herpes simplex type-2 infections. Reg Anesth. 1990;15:261-3.
4. Bader AM, Datta S, Gilbertson L, Kirz L. Regional anesthesia in women with chorioamnionitis. Reg Anesth. 1992;17:84-6.
5. Bengtsson M, Nettelblad H, Sjoberg F. Extradural catheter-related infections in patients with infected cutaneous wounds. Br J Anaesth. 1997;79:668-70.
6. Bergman BD, Hebl JR, Kent J, Horlocker TT. Neurologic complications of 405 consecutive continuous axillary catheters. Anesth Analg 2003;96:247-52.
7. Bernard N, Pirat P, Branchereau S, et al. Continuous peripheral nerve blocks in 1416 patients: A prospective multicenter study measuring incidences and characteristics of infectious adverse events. Anesthesiology 2002;96:A882.
8. Borgeat A, Ekatodramis G, Kalberer F, Benz C. Acute and nonacute complications associated with interscalene block and shoulder surgery: A prospective study. Anesthesiology 95:875-880, 2001.
9. Carp H, Bailey S. The association between meningitis and dural puncture in bacteremic rats. Anesthesiology. 1992;76:739-42.
10. Couzigou C, Vuong TK, Botherel AH, et al. Iatrogenic Streptococcus salivarius meningitis after spinal anaesthesia: need for strict application of standard precautions. J Hosp Infect 2003;53:313-4.
11. Crawford JS, James FM, Nolte H, et al. Regional analgesia for patients with chronic neurologic disease and similar conditions. Anaesthesia. 1981;36:821.
12. Crone LA, Conly JM, Storgard C, et al. Herpes labialis in parturients receiving morphine after cesarean section. Anesthesiology. 1990;73:208-13.
13. Crosby ET, Halpern SH, Rolbin SH. Epidural anaesthesia for cesarean section in patients with active recurrent genital herpes simplex infections: A retrospective review. Can J Anaesth. 1989;36:701-4.
14. Cuvillon P, Ripart J, Lalourecy L, et al. The continuous femoral nerve block catheter for postoperative analgesia: Bacterial colonization, infectious rate and adverse effects. Anesth Analg 2001;93:1045-9.
15. Darchy B, Forceville X, Bavoux E, et al. Clinical and bacteriologic survey of epidural analgesia in patients in the intensive care unit. Anesthesiology. 1996;85:988-98.
16. Du Pen SL, Peterson DG, Williams A, Bogosian AJ. Infection during chronic epidural catheterization: Diagnosis and treatment. Anesthesiology. 1990;73:905-9.
17. Horlocker TT, Wedel DJ. Regional anesthesia and infection. In: Finucane BT, ed. Complications of Regional Anesthesia. Philadelphia, PA: Saunders 1999:170-183.
18. Hughes SC, Dailey PA, Landers D, et al. Parturients infected with human immunodeficiency virus and regional anesthesia. Anesthesiology. 1995;82:32-7.
19. Jakobsen KB, Christensne MK, Carlsson PS. Extradural anaesthesia for repeated surgical treatment in the presence of infection. Br J Anaesth. 1995;75:536-40.
20. Kane RE. Neurologic deficits following epidural or spinal anesthesia. Anesth Analg 1981;60:150-61.
21. Moen V, Dahlgren N, Irestedt L. Severe neurological complications after central neuraxial blockades in Sweden 1990-1999. Anesthesiology 2004;101:950-4.
22. Ramanathan S, Sheth R, Turndorf H. Anesthesia for cesarean section in patients with genital herpes infections. A retrospective study. Anesthesiology. 1986;64:807-9.
23. Schneeberger PM, Janssen M, Voss A. Alpha-hemolytic streptococci: A major pathogen of iatrogenic meningitis following lumbar puncture. Case reports and a review of the literature. Infection. 1996;24:29-35.
24. Strafford MA, Wilder RT, Berde CB. The risk of infection from epidural analgesia in children: A review of 1620 cases. Anesth Analg. 1995;80:234-8.
25. Tom DJ, Gulevich SJ, Shapiro HM, et al. Epidural blood patch in the HIV-positive patient. Anesthesiology. 1992;76:943-63.
26. Trautmann M, Lepper PM, Schmitz F-J. Three cases of bacterial meningitis after spinal and epidural anesthesia. Eur J Clin Microbiol Infect Dis 2002;21:43-5.
27. Wang LP, Hauerberg J, Schmidt JF. Incidence of spinal epidural abscess after epidural analgesia: a national 1-year survey. Anesthesiology 1999; 91:1928-36.
28. Wang LP, Hauerberg J, Schmidt JF. Incidence of spinal epidural abscess after epidural analgesia. Anesthesiology 1999;91:1928-36.
29. Warren TM, Datta S, Ostheimer GW. Lumbar epidural anesthesia in a patient with multiple sclerosis. Anesth Analg. 1982;61:1022-3.
30. Weed LH, Wegeforth P, Ayer JB, Felton LD. The production of meningitis by release of cerebrospinal fluid during an experimental septicemia. JAMA. 1919;72:190-3.
31. Wegeforth P, Latham JR. Lumbar puncture as a factor in the causation of meningitis. Am J Med Sci. 1919;158:183-202.