THE spread of spinal anaesthesia with plain bupivacaine. Spread of spinal block in patients with rheumatoid arthritis. Methods

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1 Acta Anaesthesiol Scand 2010; 54: Printed in Singapore. All rights reserved r 2009 The Authors Journal compilation r 2009 The Acta Anaesthesiologica Scandinavica Foundation ACTA ANAESTHESIOLOGICA SCANDINAVICA doi: /j x Spread of spinal block in patients with rheumatoid arthritis K. A. LEINO 1,K.S.KUUSNIEMI 1,H.K.PÄLVE 2,J.T.KORPELAINEN 3,H.T.TIUSANEN 4 and T. T. TUPPURAINEN 1 1 Department of Anaesthesiology, Intensive Care, Emergency Care and Pain Medicine, Turku University Hospital, Turku, Finland, 2 Finnish Medical Association, Helsinki, Finland, 3 Department of Biostatistics, Turku University Hospital, Turku, Finland and 4 Department of Rheumatology, Turku University, Turku, Finland Background: In clinical practice, we noticed a greater than expected spread of sensory spinal block in patients with rheumatoid arthritis. We decided to test this impression and compared the spread of standard spinal anaesthesia in rheumatoid and non-rheumatoid control patients. Methods: Spinal anaesthesia with 3.4 ml (17 mg) of plain bupivacaine was administered to 50 patients with seropositive rheumatioid arthritis and to 50 non-rheumatoid control patients. The protocol was standardised for all patients. All the patients were undergoing lower limb surgery and the rheumatoid patients were operated on due to their rheumatoid disease. The spread of sensory block was recorded 30 min from the dural puncture using a pin prick test and a cold ice-filled container. The impact of body mass index (BMI), height and age on the spread were analysed. Results: The spread of sensory block was greater in patients with rheumatoid arthritis ( dermatomes) than in non-rheumatoid patients ( dermatomes) (Po0.05). Increasing BMI was related to cephalad spread of block in the rheumatoid group (Po0.05), but not in the control group. Conclusion: The mean spread of sensory block 30 min after the injection of plain bupivacaine was 1.5 segments cephalad in patients with rheumatoid arthritis than in those without this disease. BMI might be a patient-related factor contributing to the extent of the block in rheumatoid patients. These findings should be considered when performing a spinal block in rheumatoid patients. Accepted for publication 15 July 2009 r 2009 The Authors Journal compilation r 2009 The Acta Anaesthesiologica Scandinavica Foundation THE spread of spinal anaesthesia with plain bupivacaine is often unpredictable. 1 Several factors have been invoked as determinants of the spread of local anaesthetic solutions in cerebrospinal fluid (CSF). 2 A few studies have reported patient-dependentfactorssuchasage, 3 weight, body mass index (BMI) 4 6 and height 4 to affect the spread of block. It is also known that term parturients are prone to have quite an extended spinal block with relatively small doses of plain bupivacaine. 7 The variability in the lumbosacral CSF volume has been thought to be an important factor determining the extent and duration of sensory block. 8 We had noticed clinically that the maximum spread of spinal block seemed more extensive in patients with rheumatoid arthritis than in those without this disease. Our clinical impression inspired us to compare the spread of spinal block between rheumatoid and non-rheumatoid patients and to evaluate the effect of patient-dependent factors on the spread. This study was designed to test our hypothesis that the spread of sensory spinal block at 30 min is more extensive in rheumatoid than in non-rheumatoid patients. We found no previous reports addressing this. Methods The study protocol was reviewed and approved by the Ethics Committee of Turku University Hospital and all the patients gave their informed consent. Altogether, 100 American Society of Anesthesiologists I IV patients older than 18 years and undergoing lower limb orthopaedic surgery in spinal anaesthesia were studied. We enrolled 50 consecutive patients with seropositive rheumatoid arthritis for the study group and 50 consecutive patients 65

2 K. A. Leino et al. scheduled for elective surgery or consecutive trauma patients with single unilateral lower limb trauma for control group. Exclusion criteria were neurological disease, mental disturbance, deformities of the spinal column other than those caused by rheumatoid arthritis, allergy to local anaesthetics or any other contraindication for spinal anaesthesia. Trauma patients were excluded if they had any trauma other than single unilateral lower limb trauma. A full medical history was obtained from all patients. The protocol was standardised for all patients. The patients were premedicated with diazepam 5 10 mg orally depending on the patient s age ( 70 years 10 mg, 470 years 5 mg) and weight ( 60 kg 5mg, 460 years 10 mg). In the operation theatre, monitoring included continuous electrocardiogram, non-invasive blood pressure measurement at 5-min intervals and continuous pulse oximetry. Ringer s solution was infused to all patients and bolus doses of ephedrin 5 mg or etilefrine 3 mg were given intravenously if blood pressure decreased below 90 mmhg or earlier if clinically judged to be needed. Bradycardia was treated with glycopyrrolate 0.2 mg intravenously if the heart rate decreased below 50 beats/min. If bradycardia sustained, atropine 0.5 mg was administered. Spinal block was performed by placing the patients in the lateral decubitus position with the side to be operated uppermost. Full aseptic precautions were followed and a 29 G Quincke spinal needle with an introducer (Becton Dickinson, Madrid, Spain) was used for dural puncture performed in the midline at the L3-4 interspace. Plain bupivacaine (5 mg/ml) 3.4 ml (17 mg) was injected in 20 s when free flow of clear CSF was verified. No barbotage or aspiration was performed. All patients remained in the lateral position exactly 5 min before being turned supine for the operation. The patients were maintained supine for 25 min. During the whole procedure, the operation table was kept in the horizontal position and no tilt or other adjustments were used. Spread of sensory block was recorded 30 min from dural puncture in the midclavicular line using two methods. Loss of sharp sensation was assessed using the pin prick method and loss of cold sensation using a cold ice-filled container. The assessment was performed unilaterally on the side of surgery. To minimise the effect of variability in patient size on assessing the particular dermatome, we applied a simple method created earlier for this purpose by the authors. A stretchable rubber band 66 with markings for every dermatome from jugulum (C4) to umbilicus (Th10) was positioned in the midline of the patient. The rubber band was of optimal size for a small patient. The band was stretched so that the markings for umbilicus and jugulum were matching their anatomical sites, thus facilitating the identification of anaesthetised dermatomes according to patient size. The total number of dermatomes affected was recorded from sacral segments (S5) on. Demographic data and the level of sensory block were analysed with an unpaired t-test. A general linear model was used to analyse the impact of patient-dependent factors on the spread of block in both groups. The model included sex, age, height and BMI as fixed effects. The use of corticosteroids and the use of sytostatic drugs were also included as fixed effects in the rheumatoid group. Sample size calculation revealed that altogether, 96 patients would be needed using an a 0.05, a b 0.2 and assuming an SD of 3.5 dermatomes 6 to detect a difference of two dermatomes in the height of sensory block. A P value of o0.05 was considered to be statistically significant. Data are expressed as mean SD. Results Patient characteristics are outlined in Table 1. Patients with rheumatoid arthritis weighed less (P ) and had a lower BMI (P ) than those in the control group. The study groups were comparable in terms of gender, age and height. All the anaesthesias were uneventful. Ephedrin or etilefrine was administered to nine patients in the rheumatoid group and to six patients in the control group (NS). Bradycardia was treated in five patients in both groups. The spread of sensory block assessed with the pin prick test was dermatomes for rheu- Table 1 Patient characteristics. Rheumatoid patients Non-rheumatoid patients Women/men 37/13 30/ Age (years) Weight (kg) Height (cm) Data are given as mean SD. Weight and body mass index (BMI) were different between the groups. P

3 Spread of spinal block Pin prick test in rheumatoid patients C1 Loss of cold sensation in rheumatoid patients Fig. 1. Effect of body mass index (BMI) on the peak sensory level of spinal anaesthesia in individual patients. Greater BMI favoured higher spread of the block within the rheumatoid group assessed with the pin prick test (P ) and loss of cold sensation (P ). No effect of BMI was found in the control group of non-rheumatoid patients. Pin prick test in control patients C1 Loss of cold sensation in control patients matoid patients and dermatomes for non-rheumatoid patients from the sacral segments on (P ). The values for loss of cold sensation were and dermatomes, respectively (P ). The ranges for rheumatoid patients were L2 and those for control patients were L3 Th4, assessed with the pin prick test. The ranges assessed with loss of cold sensation were L2 C3 and L4 Th2, respectively. Figure 1 shows the BMIs of individual rheumatoid and control patients plotted against the spread of the block. Greater BMI favoured more extensive block in the rheumatoid group, while male gender and lesser height favoured more cephalad spread of sensory block only when assessed with the pin prick method as presented in Table 2. No effect of sex, age, height or BMI was found in the control group. Discussion The present study was premised on the clinical observation of the distribution of spinal block in rheumatoid patients. Our main result was that the mean spread of sensory block 30 min after the injection of plain bupivacaine is 1.5 segments greater in patients with rheumatoid arthritis than in those without this disease. This study was Table 2 Statistical significance of variables tested for affecting the spread of sensory block in patients with rheumatoid arthritis (RA) and in control patients (C) separately. P value Pin prick test Loss of cold sensation RA C RA C Sex 0.006* Age Height 0.020* BMI 0.007* * Use of corticosteroids Use of sytostatic drugs Greater body mass index (BMI) favoured more extensive block in rheumatoid patients (*Po0.05). Male gender and lesser height favoured more cephalad spread of sensory block in rheumatoid patients when assessed with the pin prick method (*Po0.05). carried out in seropositive rheumatoid patients operated on due to their rheumatoid disease, which indicates an advanced state of disease in these patients. Seropositive rheumatoid arthritis is a systemic autoimmune disease that affects the whole body. The systemic manifestations include cardiovascular, pulmonary, mucosal and blood-related distur- 67

4 K. A. Leino et al. bances. In terms of anaesthesia, these patients constitute a uniform group often characterised by special features such as swelling and reduced mobility of joints, fragility of bones, multiple deformities and complications related to corticosteroid use. In clinical practice these special features may cause problems including difficulties in performing the block and airway management. Despite the unique nature of this patient group, there are no earlier studies on rheumatoid arthritis and the extension of spinal anaesthesia. Overall, based on our literature search, patients suffering from rheumatoid arthritis have remained completely beyond the scope of prospective anaesthesia research. Increased mean spread of spinal block in rheumatoid patients is a new finding. The volume of CSF 8,9 and the degenerative and inflammatory process of the rheumatoid disease likely contribute to the spread of spinal block. CSF volume is the diluent for the local anaesthetic agent injected during spinal anaesthesia. Therefore, it is thought that lumbosacral CSF volume 8 is the primary patient-related determinant of the spread and other patient characteristics like BMI and height act on CSF volume. The lower the CSF volume, the more cephalad the block will be. Degenerative changes and neurological involvement have been observed in thoracic 10,11 and lumbar rheumatoid spine. The pathological mechanisms include joint synovitis, 17 granulomatous changes in different tissues 15 and inflammation of the discovertebral junction. 18 Epidural nodules 19 and spondylolisthesis 20 add to the effect. It is presumably much more common to have these changes to a lesser extent without any neurological disturbance or even without any back pain. 14 These changes may narrow the lumbosacral and thoracic subarachnoid space, reducing the CSF volume, thus contributing to the peak sensory block level. It can be speculated that the density of CSF may also be higher in rheumatoid patients due to the inflammatory process and increased baricity would facilitate higher spinal block. To our knowledge, there are no studies on the density of CSF in rheumatoid patients. However, CSF density varies somewhat in humans as evidenced by the fact that males have a higher CSF density than females. 21 Our results suggest that BMI might be a patientrelated factor contributing to the spread of block also in rheumatoid patients. BMI did not reach statistical significance in the control group, although increasing BMI is generally accepted to 68 be related to more cephalad distribution of spinal block in surgical patients in general. 4 6 Despite the differences in patient positioning and the related arrangements in these studies when compared with our study, there is no obvious explanation like sample size for this discrepancy. Age and patient height reached statistical significance in the rheumatoid group only when assessed with the pin prick test. No strong conclusion can be drawn from these results. There is some inconsistency in studies concerning the height and distribution of block mainly because a difference in height is mostly due to the length of lower limb bones, not the spine. A much better correlation has been achieved using spinal length instead of patient height. 22 Our method was to assess sensory block height only at 30 min. Intratechal local anaesthetics usually stop spreading before the measurement time point used, but there is some variability, and mean times above 30 min to achieve the maximum block have been reported. 4,6,23 Moreover, we could not detect a possible start of regression of the block before 30 min. There is nothing that would suggest differences in the mean time to achieve a maximum block height or regression of the block in rheumatoid patients compared with normal patients. However, our method of assessing sensory block only at 30 min is a limitation of the present study. It would have been wise to measure the spread at 10-min intervals in the beginning and to follow the patients until the regression of the block starts. The mean difference of 1.5 dermatomes in sensory spinal anaesthesia between a rheumatoid and a non-rheumatoid patient may not always be clinically significant, but the difference may be more prominent when dealing with an obese rheumatoid patient. There was also a difference in ranges between the rheumatoid and the control group. The effect of rheumatoid arthritis and BMI may be superimposed in an obese rheumatoid patient. Adverse events like hypotension and bradycardia are more profound in the case of a high spinal block. 24 These well-known and quite common cardiovascular complications may compromise patient safety. Thus, it is reasonable to attenuate the extent of these potentially detrimental adverse events by reducing the dose and volume of the local anaesthetic agent. Correspondingly, it is reasonable to take into consideration the lower than expected maximum extent of the block in case of a rheumatoid patient with a low BMI. Too low a peak sensory block extent may force the anaesthetist to

5 Spread of spinal block convert the spinal anaesthesia into general anaesthesia and this can lead to additional adversities. Overall, taking into account the impact of BMI increases the predictability of spinal block height and facilitates patient safety. Adjustment of block height could possibly be achieved by changing the lumbar interspace for dural puncture. 6 However, our results add only a piece of information to help the anaesthetist but make it by no means easy to predict the maximum spread of the block in a single patient with rheumatoid arthritis. We conclude that the mean spread of sensory block 30 min after the injection of plain bupivacaine was 1.5 segments cephalad in patients with rheumatoid arthritis than in those without this disease. BMI might be a patient-related factor in determining the extension of the block in rheumatoid patients. These findings should be considered when performing a spinal block in rheumatoid patients. References 1. Logan MR, McClure JH, Wildsmith JAW. Plain bupivacaine: an unpredictable spinal anaesthetic agent. Br J Anaesth 1986; 58: Greene NM. Distribution of local anesthetic solutions within the subarachnoid space. Anesth Analg 1985; 64: Pitkänen M, Haapaniemi L, Tuominen M, Rosenberg PH. Influence of age on spinal anaesthesia with isobaric 0.5% bupivacaine. Br J Anaesth 1984; 56: Pitkänen M. Body mass and the spread of spinal anesthesia with bupivacaine. Anesth Analg 1987; 66: Mc Cullogh WJD, Littlewood DG. Influence of obesity on spinal analgesia with isobaric 0.5% bupivacaine. Br J Anaesth 1986; 58: Taivainen T, Tuominen M, Rosenberg PH. Influence of obesity on the spread of spinal analgesia after injection of plain 0.5% bupivacaine at the L3-4 or L4-5 interspace. Br J Anaesth 1990; 64: Ben-David B, Miller G, Gavriel R, Gurevitch A. Low-dose bupivacaine fentanyl spinal anesthesia for cesarean delivery. Reg Anesth and Pain Med 2000; 25: Carpenter RL, Hogan QH, Liu SS, Crane B, Moore J. Lumbosacral cerebrospinal fluid volume is the primary determinant of sensory block extent and duration during spinal anesthesia. Anesthesiology 1998; 89: Hogan QH, Prost R, Kulier A, Taylor ML, Liu S, Mark L. Magnetic resonance imaging of cerebrospinal fluid volume and influence of body habitus and abdominal pressure. Anaesthesiology 1996; 84: Shichikawa K, Matsui K, Oze K, Ota H. Rheumatoid spondylitis. Int Orthop 1978; 2: van der Horst-Bruinsma IE, Markusse HM, Macfarlene JD, Vielvoye CJ. Rheumatoid discitis with cord compression at the thoracic level. Br J Rheumatol 1990; 29: Hauge T, Magnaes B, Skullerud K. Rheumatoid arthritis of the lumbar spine leading to anterior vertebral subluxation and compression of the cauda equine. Scand J Rheumatol 1980; 9: Biasi D, Caramaschi B, Carletto A, Pacor ML, Bambara LM. A case of rheumatoid arthritis with lumbar spine involvement. Rheumatol Int 1995; 15: Kawaguchi Y, Matsuno H, Kanamori M, Ishihara H, Ohmori K, Kimura T. Radiological findings of the lumbar spine in patients with rheumatoid arthritis and a review of pathological mechanisms. J Spinal Disord Tech 2003; 16: Nakase T, Fujiwara K, Kohno J, Owaki H, Tomita T, Yonenobu K, Ochi T. Pathological fracture of a lumbar vertebra caused by rheumatoid arthritis: a case report. Int Orthop 1998; 22: Sakai T, Sairyo K, Hamada D, Higashino K, Katoh S, Takata Y, Shinomiya F, Yasui N. Radiological features of lumbar spinal lesions in patients with rheumatoid arthritis with special reference to the changes around intervertebral discs. Spine J 2008; 8: Sims-Williams H, Jayson MIV, Baddeley H. Rheumatoid involvement of the lumbar spine. Ann Rheum Dis 1977; 36: Martel W. Pathogenesis of cervical discovertebral destruction in rheumatoid arthritis. Arthritis Rheum 1977; 20: Friedman H. Intraspinal rheumatoid nodule causing nerve root compression. J Neurosurg 1970; 32: Magnaes B, Hauge T. Rheumatoid arthritis contributing to lumbar spinal stenosis. Neurogenic intermittent claudication. Scand J Rheumatol 1978; 7: Shiffer E, Van Gessel E, Gamulin Z. Influence of sex on cerebrospinal fluid density in adults. Br J Anaesth 1999; 83: Hartwell BL, Aglio LS, Hauch MA, Datta S. Vertebral column length and spread of hyperbaric subarachnoid bupivacaine in the term parturients. Reg Anesth 1991; 16: Orko R, Pitkänen M, Rosenberg PH. Subarachnoid anaesthesia with 0.75% bupivacaine in patients with chronic renal failure. Br J Anaesth 1986; 58: Tarkkila PJ, Kaukinen S. Complications during spinal anesthesia: a prospective study. Reg Anesth 1991; 16: Address: Kari Leino Department of Anaesthesiology, Intensive Care, Emergency Care and Pain Medicine Turku University Hospital Kiinamyllynkatu 4-8 Turku, FIN Finland kari.leino@tyks.fi 69