British Journal of Anaesthesia 1990; 65: 504-507
SPINAL ANAESTHESIA WITH PLAIN 0.5% BUPIVACAINE AT 19 °C AND 37 °C E. KRISTOFFERSEN, E. SLOTH, J. C. HUSTED, A. B. BACH, H. C. HUSEGAARD AND I. ZULOW
Forty-five men aged 50-80 yr undergoing urological surgery under spinal anaesthesia were allocated randomly to three groups. All patients received 0.5% plain bupivacaine 3 ml injected at the L2-3 interspace. The temperature of the solution in group 1 was 19 °C, in groups 2 and 3 37 °C. In groups 1 and 2 the injection was performed with the patient sitting; in group 3 the patient was in a lateral horizontal position. Spread of block, intensity of motor block and cardiovascular stability were measured. Warming the solution from 19 °C to 37 °C before spinal injection with the patient in the sitting position did not significantly affect these variables. However, the extent of analgesia was reduced significantly when the 37 °C solution was injected with the patient in the lateral horizontal compared with the sitting position. KEY WORDS Anaesthetics, local: bupivacaine. injectate temperature. Anaesthetic techniques: spinal.
Factors expected to influence spread of spinal analgesia have been studied intensively by several groups [1—9]. However, temperature of injected anaesthetic solutions has not received much attention until recently. In 1988, Beardsworth and colleagues reported that the temperature of a solution injected into a spinal canal model affected its distribution [10]. In a clinical study with 0.5 % plain bupivacaine, Stienstra and van Poorten injected solutions at temperatures of 4 CC and 37 °C with patients sitting. They found a significantly higher cephalad spread of analgesia in the 37 °C group [11]. In a recent study, Beardsworth and Lambert injected
the solutions at 37 °C and 20 °C, but with the patient in the horizontal position. They found no difference in cephalad spread of analgesia, but a longer duration after injection of solution at body temperature [12]. The purpose of this study was to evaluate the clinical effect of using a solution of 0.5 % plain bupivacaine at 37 °C instead of room temperature, injected in the sitting patient. PATIENTS AND METHODS
We studied 45 men (ages 50-80 yr) undergoing cystoscopy or transurethral resection of the prostate. None of the patients suffered from neurological disease or deformity of the spine, and no patient had a history of hypersensitivity to local anaesthetics. Informed consent was obtained from all patients, and the study was approved by the local Ethics Committee. The patients were allocated randomly to three groups, each of 15 patients. All received plain 0.5 % bupivacaine 3 ml over 30s after lumbar puncture at the L2-3 interspace with a 25-gauge needle. Before this procedure isotonic saline 500 ml was infused i.v. In group 1 the temperature of the anaesthetic solution was 19 °C (room temperature), and the injection was performed with the patient sitting. The patient was kept sitting for 2 min and then placed in the lithotomy position. In group 2 the temperature of the anaesthetic solution at in-
E. KRISTOFFERSEN*, M.D.; E. SLOTH, M.D.; J. C. HUSTHD, M.D.; A . B . B A C H , M.D.; H. C. HUSEGAARD, M.D.; I. ZOLOW, M.D.;
Department of Anaesthesia, Central Hospital of Randers, DK 8900 Randers, Denmark. Accepted for Publication: April 10, 1990. *Address for correspondence: Egevej 44, DK-8680 Ry, Denmark.
Downloaded from http://bja.oxfordjournals.org/ at University of California, San Fransisco on March 29, 2015
SUMMARY
SPINAL ANAESTHESIA WITH BUPIVACAINE
505
TABLE I. Patient data: mean (SD) age, height and weight. No significant differences between groups
Number Age (yr) Height (cm) Weight (kg)
Group 1 (19 "C, sitting)
Group 2 (37 °C, sitting)
Group 3 (37 °C, horizontal)
15 70.1(7.7) 173.2(5.0) 74.2(12.1)
15 67.8(7.0) 173.3(6.2) 78.3(10.3)
15 69.5(7.1) 172.3(7.8) 81.3(15.1)
3, range (0-10) indicates segments C8-T10. * P < 0.05 between groups 2 and 3 Maximum spread Thoracic dermatome
Group 1 (19 °C, sitting)
Group 2 (37 °C, sitting)
5.4(3-10)
4.6(2-8)
jection was 37 °C (body temperature) after temperature equilibration in water, and the position identical to that of group 1. In group 3 the temperature of the anaesthetic solution was 37 °C and injection was performed with the patient in the lateral horizontal position. The patient was placed immediately in the supine position, and after a further 2 min, in the lithotomy position. Arterial pressure was measured at 5-min intervals and ECG was monitored continuously. The cephalad spread of analgesia was assessed as the dermatomal segment in which sensation to midline pinprick was lost, characterized by incomplete analgesia. Motor block was assessed by the Bromage scale (scores 3-0). Testing was performed 5, 10, 15, 20 and 30 min after administration of bupivacaine, and thereafter every 30 min until sensory block had recovered to T10 level. All patients were tested for at least 120 min. The investigator undertaking these tests was unaware of the temperature of the anaesthetic solution and the initial positioning of the patient. Side effects were noted, and ephedrine 5 mg was administered i.v. if systolic arterial pressure decreased by more dian 25%. All statistical comparisons were made between group 1 and group 2 (different temperature) and between group 2 and group 3 (different posture) using the Mann-Whitney non-parametric test. P < 0.05 was taken as significant. RESULTS
There were no significant differences between the three groups in patient age, height or weight (table I).
Group 3 (37 °C, horizontal) *
6.3(0-10)
C8T1-
§
2-
AA
3-
A
A-
AAAA
OO
Si +s
cCD
C.
°
AAAAAA
OOO
A
oo
? 6-
ooo
78-
A
oo
910FIG. 1. Maximal cephalad spread of analgesia in groups 1 ( • ) . 2 (A) and 3 (O)- Horizontal bars represent median values.
Cephalad spread of analgesia
The most extensive cephalad spread of analgesia was seen in group 2 and the least in group 3 (table II, fig. 1). The difference was significant only between these two groups. Nevertheless, the patient in whom analgesia reached the highest segmental level (C8) was in group 3. Generally, the range was larger and the predictability lower
Downloaded from http://bja.oxfordjournals.org/ at University of California, San Fransisco on March 29, 2015
TABLE II. Maximum cephalad spread of analgesia, thoracic segments {median values (range)). In group
BRITISH JOURNAL OF ANAESTHESIA
506
TABLE III. Duration of complete analgesia in segmental levels T6—10 (median values (range)). *P < 0.05 between groups 2 and 3
Dermatome T10 T8 T6
Group 1 (19 °C, sitting)
Group 2 (37 °C, sitting)
110(0-276) 69(0-191) 50(0-110)
155(38-221) 123(0-171) 63(0-149)
Group 3 (37 °C, horizontal) * *
122(0-199) 40(0-168) 0(0-123)
Pressure decrease (% of initial value)
Group 1 (19 °C, sitting)
Group 2 (37 °C, sitting)
Group 3 (37 °C, horizontal)
14(0-35)
21(0--i9)
15(2-30)
in this group compared with the others. The smallest range was found in group 2. Duration of analgesia The duration of analgesia in segmental levels T6-10 was marginally longer in group 2 than in groups 1 and 3 (table III). At the T10 level the differences were not significant, but at the other levels tested the differences between group 2 and 3 were significant. In all groups the range was very large, and complete analgesia at the T10 level was obtained by every patient only in group 2. All groups contained patients without analgesia at the T6 and T8 levels (table III). Motor block Scale 3 block or total paralysis was seen in 14 of 15 patients in both groups 1 and 3. In group 2 this was obtained in 13 of 15 patients. Cardiovascular stability The decrease in systolic arterial pressure during the first 30 min was most pronounced in group 2, but this was not significant (table IV). Consumption of ephedrine did not differ in the three groups. No patient developed major cardiovascular or pulmonary problems. DISCUSSION
Extent of analgesia after subarachnoid injection of plain bupivacaine has been shown to be affected primarily by total dose [2, 3] and other factors have been thought to be of minor importance [2-4, 7-9]. Stienstra and van Poorten reported
that changing the temperature of plain bupivacaine modified analgesia considerably [11]. However, the clinical relevance of this study was limited, as a temperature of 4 °C is probably not used in clinical practice. They found significantly greater cephalad spread and smaller variance in the 37 °C group, when the injection was performed with the patient in the sitting position. The authors postulated that the temperature effect was caused by difference in baricity, although it was admitted that this was small [11]. Our results are at variance with these data, but it must be emphasized that the studies differed in several ways. We found only minor and non-significant differences in maximal cephalad spread of analgesia between group 1(19 °C, sitting position) and group 2 (37 °C, sitting position), and the same pattern was seen for duration of analgesia in segments T6-10, intensity of motor block and cardiovascular stability. However, cephalad spread of analgesia was approximately one segment higher and the duration 10-50 min longer when the warm solution was injected. It must be emphasized that regression of analgesia below T10 was not monitored consistently. In accordance with the data of Stienstra and van Poorten [11], the variability seemed to be smaller in group 2 than group 1, possibly because the time for temperature equilibration was an important factor influencing the spread of analgesia in the latter group. The difference in cephalad spread in the two studies may be explained by greater difference in temperature of the solutions used by Stienstra and van Poorten. Recently, Stienstra and colleagues have ex-
Downloaded from http://bja.oxfordjournals.org/ at University of California, San Fransisco on March 29, 2015
TABLE IV. Maximal decrease in systolic arterial pressure during the first 30 mm (median values (range)). No significant differences
SPINAL ANAESTHESIA WITH BUPIVACAINE
REFERENCES 1. Chambers WA, Littlewood DG, Edstrom HH, Scott DB.
2.
3. 4.
5.
6.
7.
8.
9.
10.
11. 12. 13.
Spinal anaesthesia with hyperbaric bupivacaine: Effects of concentration and volume administered. British Journal of Anaesthesia 1982; 54: 75-79. Sheskey MC, Rocco AG, Bizzarri-Schmid M, Francis DM, Edstrom H, Covino BG. A dose-response study of bupivacaine for spinal anesthesia. Anesthesia and Analgesia 1983; 62: 931-935. Logan MR, McClure JH, Wildsmith JAW. Plain bupivacaine : An unpredictable spinal anaesthetic agent. British Journal of Anaesthesia 1986; 58: 292-296. Touminen M, Kalso E, Rosenberg PH. Effects of posture on the spread of spinal anaesthesia with isobaric 0.75 % or 0.5% bupivacaine. British Journal of Anaesthesia 1982; 54: 313-318. Sundnes KO, Vaagenes P, Skretting P, Lind B, Edstrom HH. Spinal analgesia with hyperbaric bupivacaine: Effects of volume of solution. British Journal of Anaesthesia 1982; 54: 69-73. Axelsson KH, Edstrom HH, Sundberg AEA, Widman GB. Spinal anaesthesia with hyperbaric 0.5% bupivacaine: Effects of volume. Ada Anaesthesiologica ScanaHnavica 1982; 26: 439-445. Bengtsson M, Malmquist L-A, Edstrom HH. Spinal analgesia with glucose free bupivacaine—effects of volume and concentration. Acta Anaesthesiologica Scandinavica 1984; 28: 583-586. Nielsen TH, Kristoffersen E, Olsen KH, Larsen HV, Husegaard HC, Wernberg M. Plain bupivacaine 0.5 % or 0.25 % for spinal analgesia. British Journal of Anaesthesia 1989; 62: 164-167. Olsen KH, Nielsen TH, Kristoffersen E, Husegaard HC, Wemberg M, Derup J. Spinal analgesia with plain 0.5 % bupivacaine administered at spinal interspace L2-3 or L4-5. British Journal of Anaesthesia 1990; 64: 170-172. Beardsworth D , Datta S, Arthur GR, Lambert DH. The effect of temperature on the distribution of 0.5 % plain bupivacaine in a simple spinal canal model. Regional Anesthesia 1988; 13: 25-28. Stienstra R, van Poorten JF. The temperature of bupivacaine 0.5 % affects the sensory level of spinal anesthesia. Anesthesia and Analgesia 1988; 67: 272-276. Beardsworth D , Lambert DH. Wanning 0.5% bupivacaine to 37 °C increases duration of spinal anaesthesia. Regional Anaesthesia 1989; 14: 199-202. Stienstra R, Gielen M, van Poorten F, Kroon JW. Spinal anesthesia with plain bupivacaine 0.5 %: Regression of sensory and motor blockade with different temperatures of the anesthetic solution. Anesthesia and Analgesia 1989; 69: 593-597.
Downloaded from http://bja.oxfordjournals.org/ at University of California, San Fransisco on March 29, 2015
amined the use of 0.5 % plain bupivacaine at temperatures of 20 °C and 37 °C [13]. The solutions were injected with the patients in the sitting position. They reported a significantly higher maximal cephalad spread and longer duration of analgesia with the warm solution. These data cannot be confirmed by our study. In the Dutch study, patients were kept sitting for longer after the injection was completed, and this may be responsible for some differences in spread of analgesia. Comparing group 2 (37 °C, sitting position) and group 3 (37 °C, horizontal position) we found significant differences in maximal cephalad spread and a greater variance in group 3. Thus the warm solution may be slightly hypobaric, with more unpredictable spread when injected with the patient in the lateral horizontal position. Our data support the view that the baricity of the solutions used by Stienstra and van Poorten was responsible at least partly for the different spread observed [11]. Movement of a hypobaric solution in the horizontal spinal canal would be expected to be dependent on the extent of individual spinal curvature, and this probably explains the large variability in group 3. The duration of analgesia in the higher segmental levels (T6-8) was significantly longer in group 2 than in group 3, but no difference was found in duration at T10, or in motor block or cardiovascular stability between the two groups. According to Beardsworth and Lambert, duration of analgesia should be increased by warming a spinal solution, but in their study injections were made always with the patient in the lateral horizontal position [12]. Thus their study and ours are not directly comparable.
507
SPINAL ANAESTHESIA WITH PLAIN 0.5% BUPIVACAINE AT 19 °C AND 37 °C E. KRISTOFFERSEN, E. SLOTH, J. C. HUSTED, A. B. BACH, H. C. HUSEGAARD AND I. ZULOW
Forty-five men aged 50-80 yr undergoing urological surgery under spinal anaesthesia were allocated randomly to three groups. All patients received 0.5% plain bupivacaine 3 ml injected at the L2-3 interspace. The temperature of the solution in group 1 was 19 °C, in groups 2 and 3 37 °C. In groups 1 and 2 the injection was performed with the patient sitting; in group 3 the patient was in a lateral horizontal position. Spread of block, intensity of motor block and cardiovascular stability were measured. Warming the solution from 19 °C to 37 °C before spinal injection with the patient in the sitting position did not significantly affect these variables. However, the extent of analgesia was reduced significantly when the 37 °C solution was injected with the patient in the lateral horizontal compared with the sitting position. KEY WORDS Anaesthetics, local: bupivacaine. injectate temperature. Anaesthetic techniques: spinal.
Factors expected to influence spread of spinal analgesia have been studied intensively by several groups [1—9]. However, temperature of injected anaesthetic solutions has not received much attention until recently. In 1988, Beardsworth and colleagues reported that the temperature of a solution injected into a spinal canal model affected its distribution [10]. In a clinical study with 0.5 % plain bupivacaine, Stienstra and van Poorten injected solutions at temperatures of 4 CC and 37 °C with patients sitting. They found a significantly higher cephalad spread of analgesia in the 37 °C group [11]. In a recent study, Beardsworth and Lambert injected
the solutions at 37 °C and 20 °C, but with the patient in the horizontal position. They found no difference in cephalad spread of analgesia, but a longer duration after injection of solution at body temperature [12]. The purpose of this study was to evaluate the clinical effect of using a solution of 0.5 % plain bupivacaine at 37 °C instead of room temperature, injected in the sitting patient. PATIENTS AND METHODS
We studied 45 men (ages 50-80 yr) undergoing cystoscopy or transurethral resection of the prostate. None of the patients suffered from neurological disease or deformity of the spine, and no patient had a history of hypersensitivity to local anaesthetics. Informed consent was obtained from all patients, and the study was approved by the local Ethics Committee. The patients were allocated randomly to three groups, each of 15 patients. All received plain 0.5 % bupivacaine 3 ml over 30s after lumbar puncture at the L2-3 interspace with a 25-gauge needle. Before this procedure isotonic saline 500 ml was infused i.v. In group 1 the temperature of the anaesthetic solution was 19 °C (room temperature), and the injection was performed with the patient sitting. The patient was kept sitting for 2 min and then placed in the lithotomy position. In group 2 the temperature of the anaesthetic solution at in-
E. KRISTOFFERSEN*, M.D.; E. SLOTH, M.D.; J. C. HUSTHD, M.D.; A . B . B A C H , M.D.; H. C. HUSEGAARD, M.D.; I. ZOLOW, M.D.;
Department of Anaesthesia, Central Hospital of Randers, DK 8900 Randers, Denmark. Accepted for Publication: April 10, 1990. *Address for correspondence: Egevej 44, DK-8680 Ry, Denmark.
Downloaded from http://bja.oxfordjournals.org/ at University of California, San Fransisco on March 29, 2015
SUMMARY
SPINAL ANAESTHESIA WITH BUPIVACAINE
505
TABLE I. Patient data: mean (SD) age, height and weight. No significant differences between groups
Number Age (yr) Height (cm) Weight (kg)
Group 1 (19 "C, sitting)
Group 2 (37 °C, sitting)
Group 3 (37 °C, horizontal)
15 70.1(7.7) 173.2(5.0) 74.2(12.1)
15 67.8(7.0) 173.3(6.2) 78.3(10.3)
15 69.5(7.1) 172.3(7.8) 81.3(15.1)
3, range (0-10) indicates segments C8-T10. * P < 0.05 between groups 2 and 3 Maximum spread Thoracic dermatome
Group 1 (19 °C, sitting)
Group 2 (37 °C, sitting)
5.4(3-10)
4.6(2-8)
jection was 37 °C (body temperature) after temperature equilibration in water, and the position identical to that of group 1. In group 3 the temperature of the anaesthetic solution was 37 °C and injection was performed with the patient in the lateral horizontal position. The patient was placed immediately in the supine position, and after a further 2 min, in the lithotomy position. Arterial pressure was measured at 5-min intervals and ECG was monitored continuously. The cephalad spread of analgesia was assessed as the dermatomal segment in which sensation to midline pinprick was lost, characterized by incomplete analgesia. Motor block was assessed by the Bromage scale (scores 3-0). Testing was performed 5, 10, 15, 20 and 30 min after administration of bupivacaine, and thereafter every 30 min until sensory block had recovered to T10 level. All patients were tested for at least 120 min. The investigator undertaking these tests was unaware of the temperature of the anaesthetic solution and the initial positioning of the patient. Side effects were noted, and ephedrine 5 mg was administered i.v. if systolic arterial pressure decreased by more dian 25%. All statistical comparisons were made between group 1 and group 2 (different temperature) and between group 2 and group 3 (different posture) using the Mann-Whitney non-parametric test. P < 0.05 was taken as significant. RESULTS
There were no significant differences between the three groups in patient age, height or weight (table I).
Group 3 (37 °C, horizontal) *
6.3(0-10)
C8T1-
§
2-
AA
3-
A
A-
AAAA
OO
Si +s
cCD
C.
°
AAAAAA
OOO
A
oo
? 6-
ooo
78-
A
oo
910FIG. 1. Maximal cephalad spread of analgesia in groups 1 ( • ) . 2 (A) and 3 (O)- Horizontal bars represent median values.
Cephalad spread of analgesia
The most extensive cephalad spread of analgesia was seen in group 2 and the least in group 3 (table II, fig. 1). The difference was significant only between these two groups. Nevertheless, the patient in whom analgesia reached the highest segmental level (C8) was in group 3. Generally, the range was larger and the predictability lower
Downloaded from http://bja.oxfordjournals.org/ at University of California, San Fransisco on March 29, 2015
TABLE II. Maximum cephalad spread of analgesia, thoracic segments {median values (range)). In group
BRITISH JOURNAL OF ANAESTHESIA
506
TABLE III. Duration of complete analgesia in segmental levels T6—10 (median values (range)). *P < 0.05 between groups 2 and 3
Dermatome T10 T8 T6
Group 1 (19 °C, sitting)
Group 2 (37 °C, sitting)
110(0-276) 69(0-191) 50(0-110)
155(38-221) 123(0-171) 63(0-149)
Group 3 (37 °C, horizontal) * *
122(0-199) 40(0-168) 0(0-123)
Pressure decrease (% of initial value)
Group 1 (19 °C, sitting)
Group 2 (37 °C, sitting)
Group 3 (37 °C, horizontal)
14(0-35)
21(0--i9)
15(2-30)
in this group compared with the others. The smallest range was found in group 2. Duration of analgesia The duration of analgesia in segmental levels T6-10 was marginally longer in group 2 than in groups 1 and 3 (table III). At the T10 level the differences were not significant, but at the other levels tested the differences between group 2 and 3 were significant. In all groups the range was very large, and complete analgesia at the T10 level was obtained by every patient only in group 2. All groups contained patients without analgesia at the T6 and T8 levels (table III). Motor block Scale 3 block or total paralysis was seen in 14 of 15 patients in both groups 1 and 3. In group 2 this was obtained in 13 of 15 patients. Cardiovascular stability The decrease in systolic arterial pressure during the first 30 min was most pronounced in group 2, but this was not significant (table IV). Consumption of ephedrine did not differ in the three groups. No patient developed major cardiovascular or pulmonary problems. DISCUSSION
Extent of analgesia after subarachnoid injection of plain bupivacaine has been shown to be affected primarily by total dose [2, 3] and other factors have been thought to be of minor importance [2-4, 7-9]. Stienstra and van Poorten reported
that changing the temperature of plain bupivacaine modified analgesia considerably [11]. However, the clinical relevance of this study was limited, as a temperature of 4 °C is probably not used in clinical practice. They found significantly greater cephalad spread and smaller variance in the 37 °C group, when the injection was performed with the patient in the sitting position. The authors postulated that the temperature effect was caused by difference in baricity, although it was admitted that this was small [11]. Our results are at variance with these data, but it must be emphasized that the studies differed in several ways. We found only minor and non-significant differences in maximal cephalad spread of analgesia between group 1(19 °C, sitting position) and group 2 (37 °C, sitting position), and the same pattern was seen for duration of analgesia in segments T6-10, intensity of motor block and cardiovascular stability. However, cephalad spread of analgesia was approximately one segment higher and the duration 10-50 min longer when the warm solution was injected. It must be emphasized that regression of analgesia below T10 was not monitored consistently. In accordance with the data of Stienstra and van Poorten [11], the variability seemed to be smaller in group 2 than group 1, possibly because the time for temperature equilibration was an important factor influencing the spread of analgesia in the latter group. The difference in cephalad spread in the two studies may be explained by greater difference in temperature of the solutions used by Stienstra and van Poorten. Recently, Stienstra and colleagues have ex-
Downloaded from http://bja.oxfordjournals.org/ at University of California, San Fransisco on March 29, 2015
TABLE IV. Maximal decrease in systolic arterial pressure during the first 30 mm (median values (range)). No significant differences
SPINAL ANAESTHESIA WITH BUPIVACAINE
REFERENCES 1. Chambers WA, Littlewood DG, Edstrom HH, Scott DB.
2.
3. 4.
5.
6.
7.
8.
9.
10.
11. 12. 13.
Spinal anaesthesia with hyperbaric bupivacaine: Effects of concentration and volume administered. British Journal of Anaesthesia 1982; 54: 75-79. Sheskey MC, Rocco AG, Bizzarri-Schmid M, Francis DM, Edstrom H, Covino BG. A dose-response study of bupivacaine for spinal anesthesia. Anesthesia and Analgesia 1983; 62: 931-935. Logan MR, McClure JH, Wildsmith JAW. Plain bupivacaine : An unpredictable spinal anaesthetic agent. British Journal of Anaesthesia 1986; 58: 292-296. Touminen M, Kalso E, Rosenberg PH. Effects of posture on the spread of spinal anaesthesia with isobaric 0.75 % or 0.5% bupivacaine. British Journal of Anaesthesia 1982; 54: 313-318. Sundnes KO, Vaagenes P, Skretting P, Lind B, Edstrom HH. Spinal analgesia with hyperbaric bupivacaine: Effects of volume of solution. British Journal of Anaesthesia 1982; 54: 69-73. Axelsson KH, Edstrom HH, Sundberg AEA, Widman GB. Spinal anaesthesia with hyperbaric 0.5% bupivacaine: Effects of volume. Ada Anaesthesiologica ScanaHnavica 1982; 26: 439-445. Bengtsson M, Malmquist L-A, Edstrom HH. Spinal analgesia with glucose free bupivacaine—effects of volume and concentration. Acta Anaesthesiologica Scandinavica 1984; 28: 583-586. Nielsen TH, Kristoffersen E, Olsen KH, Larsen HV, Husegaard HC, Wernberg M. Plain bupivacaine 0.5 % or 0.25 % for spinal analgesia. British Journal of Anaesthesia 1989; 62: 164-167. Olsen KH, Nielsen TH, Kristoffersen E, Husegaard HC, Wemberg M, Derup J. Spinal analgesia with plain 0.5 % bupivacaine administered at spinal interspace L2-3 or L4-5. British Journal of Anaesthesia 1990; 64: 170-172. Beardsworth D , Datta S, Arthur GR, Lambert DH. The effect of temperature on the distribution of 0.5 % plain bupivacaine in a simple spinal canal model. Regional Anesthesia 1988; 13: 25-28. Stienstra R, van Poorten JF. The temperature of bupivacaine 0.5 % affects the sensory level of spinal anesthesia. Anesthesia and Analgesia 1988; 67: 272-276. Beardsworth D , Lambert DH. Wanning 0.5% bupivacaine to 37 °C increases duration of spinal anaesthesia. Regional Anaesthesia 1989; 14: 199-202. Stienstra R, Gielen M, van Poorten F, Kroon JW. Spinal anesthesia with plain bupivacaine 0.5 %: Regression of sensory and motor blockade with different temperatures of the anesthetic solution. Anesthesia and Analgesia 1989; 69: 593-597.
Downloaded from http://bja.oxfordjournals.org/ at University of California, San Fransisco on March 29, 2015
amined the use of 0.5 % plain bupivacaine at temperatures of 20 °C and 37 °C [13]. The solutions were injected with the patients in the sitting position. They reported a significantly higher maximal cephalad spread and longer duration of analgesia with the warm solution. These data cannot be confirmed by our study. In the Dutch study, patients were kept sitting for longer after the injection was completed, and this may be responsible for some differences in spread of analgesia. Comparing group 2 (37 °C, sitting position) and group 3 (37 °C, horizontal position) we found significant differences in maximal cephalad spread and a greater variance in group 3. Thus the warm solution may be slightly hypobaric, with more unpredictable spread when injected with the patient in the lateral horizontal position. Our data support the view that the baricity of the solutions used by Stienstra and van Poorten was responsible at least partly for the different spread observed [11]. Movement of a hypobaric solution in the horizontal spinal canal would be expected to be dependent on the extent of individual spinal curvature, and this probably explains the large variability in group 3. The duration of analgesia in the higher segmental levels (T6-8) was significantly longer in group 2 than in group 3, but no difference was found in duration at T10, or in motor block or cardiovascular stability between the two groups. According to Beardsworth and Lambert, duration of analgesia should be increased by warming a spinal solution, but in their study injections were made always with the patient in the lateral horizontal position [12]. Thus their study and ours are not directly comparable.
507
