Spinal anaesthesia with 0.5% hyperbaric bupivacaine in elderly patients: effects of duration spent in the sitting position

B. T. Veering*,1, T. T. M. Immink-Speet1,2, A. G. L. Burm1, R. Stienstra1 and J. W. van Kleef1

1Department of Anaesthesiology, Leiden University Medical Center, Albinusdreef 2, 2333 ZA Leiden, The Netherlands 2Present address: Department of Anaesthesiology, Stichting Streekziekenhuis Coevorden-Hardenberg, M. van Thijnensingel 1, 7741 GB Coevorden, The Netherlands*Corresponding author

Accepted for publication: June 12, 2001


    Abstract
 Top
 Abstract
 Introduction
 Methods
 Results
 Discussion
 References
 
Sixty patients, aged 65–84 yr, undergoing minor urological surgery under spinal anaesthesia remained sitting for 2 (group 1, n=15), 5 (group 2, n=15), 10 (group 3, n=15), or 20 (group 4, n=15) min after completion of the subarachnoid administration of 3 ml of a 0.5% hyperbaric bupivacaine solution. They were then placed in the supine position. Analgesia levels were assessed bilaterally using pinprick. Motor block was scored using a 12-point scale. Systolic and diastolic arterial pressures and heart rate were also recorded. Twenty minutes after the injection the upper analgesia levels were lower (P<0.05) in group 4 (median T9.0) than in the groups 1–3 (medians T6.6–T8.5). The highest obtained levels (medians T5.7–T8.0) did not differ between the groups, but occurred later (P<0.05) in group 4 (median 35 min) than in groups 1–3 (medians 19–24 min). There were no significant differences in the maximum degree of motor block or haemodynamic changes between the four study groups.

Br J Anaesth 2001; 87: 738–42

Keywords: anaesthetic techniques, subarachnoid; anaesthetics local, bupivacaine; age factors


    Introduction
 Top
 Abstract
 Introduction
 Methods
 Results
 Discussion
 References
 
Clinical studies have shown that the characteristics of neural block after subarachnoid administration of hyperbaric bupivacaine change with increasing age.13 In particular, the level of analgesia extends approximately three to four segments higher in elderly compared with young adult patients. Old age and high levels of analgesia appear to be the two main factors associated with the development of hypotension during spinal anaesthesia.4 The degree of hypotension correlates with the level of sympathetic block, which is generally two to four segments higher than the level of analgesia.5 From a clinical point of view, it is, therefore, important to limit the level of sympathetic block. A spinal technique that prevents unnecessary high levels of analgesia and sympathetic block in elderly patients is, therefore, recommended. One of the benefits claimed for hyperbaric solutions is that their spread can be controlled by posture.6 The position of the patient at the time of injection may affect the direction of subarachnoid distribution, at least initially. There is, however, still discussion about the duration of the sitting period that is needed to limit the spread of analgesia.79

The present study examined the influence of different periods of sitting, before the patient is placed in the supine horizontal position, on the spread of analgesia following subarachnoid administration of a hyperbaric bupivacaine solution in elderly patients.


    Methods
 Top
 Abstract
 Introduction
 Methods
 Results
 Discussion
 References
 
We studied 57 male and three female patients (ASA I–III, age 65–84 yr), undergoing minor urological surgery under spinal anaesthesia. The study was approved by the Medical Ethics Committee of the Leiden University Medical Center and informed consent was obtained from all patients. Patients with diabetes, a history of neurological disease, or coagulopathy were excluded. Patients were randomly allocated to one of the four study groups, which differed with respect to the time during which the patients remained in the sitting position after the spinal injection. A randomization table was made before the start of the study and codes were stored in sealed envelopes, which were opened shortly before the subarachnoid injection.

Patients were pre-medicated with temazepam 10 mg orally and atropine 0.25 mg i.m., 45 min before the induction of spinal anaesthesia. Before the spinal injection, 500 ml of glucose in saline was administered by rapid i.v. infusion. Dural puncture was performed with the patient in the sitting position by a standard midline approach using a 25-gauge Quincke spinal needle via an 18-gauge introducer. When a free flow of clear cerebrospinal fluid was obtained and after aspiration of 0.2 ml of spinal fluid, 3 ml of 0.5% bupivacaine in 8% glucose (Marcaine Heavy, specific gravity 1.026 at 20°C) was injected at room temperature at a rate of 0.2 ml s–1. Patients remained sitting for 2 (group 1, n=15), 5 (group 2, n=15), 10 (group 3, n=15), or 20 (group 4, n=15) min after completion of the subarachnoid injection. They were then placed in the supine horizontal position.

Analgesia was assessed bilaterally in the anterior axillary line by pinprick using a short beveled 25-gauge needle. Assessments were made every 5 min during the first 30 min after the injection and at 45 and 60 min. Analgesia was defined as inability to detect a sharp pinprick. Motor block of the lower limbs was evaluated by asking the patient to raise the extended leg (flexion of the hip), flex the knee, and flex the ankle. It was rated per joint (0=no, 1=partial, 2=complete motor block). The results obtained in both extremities were added, giving a maximum score of 12 (complete motor block). Assessments of motor block were made immediately after the assessment of the analgesia levels. The time to maximum cephalad spread of analgesia, the highest level of analgesia attained and the maximum degree of motor block were recorded. During the first 20 min, all assessments were made by the anaesthetist who performed the lumbar puncture. Assessments at 30, 45, and 60 min (i.e. when all patients were lying supine) were made by another anaesthetist who was unaware of the period of sitting.

Systemic arterial pressure, measured with an automatic cycling device (Accutor 1, Datascope) and heart rate (HR) (from the electrocardiogram) were monitored before the subarachnoid injection, after induction of spinal anaesthesia, during surgery and in the recovery room at 5-min intervals during the first 30 min, then at 15 min intervals until the patients were returned to the ward. If the systolic arterial pressure (SAP) decreased more than 30% below the pre-anaesthetic value or to less than 90 mm Hg, ephedrine 5 mg was given intravenously. Bradycardia (HR <55 beats min–1) was treated with atropine sulphate 0.25 mg intravenously.

Group sizes were based on a power analysis, which demonstrated that with a variance s2=3.39 in the upper level of analgesia (as observed in a previous study in elderly patients),2 15 patients would be required per group to have an 80% probability of detecting a difference of two segments between group means at the 0.05 level of significance. Data are presented as mean (SD), mean (95% confidence interval), median (95% confidence interval), or frequencies, as appropriate. Medians and the corresponding 95% confidence intervals were corrected for the presence of tied observations.10 Maximum changes in SAP and HR were analysed using one-way analysis of variance. Changes in analgesia levels, as well as analgesia levels after 20 min, the highest analgesia levels and the times at which maximum analgesia levels and maximum changes in SAP and HR were reached were analysed with the Kruskal– Wallis test, followed by the non-parametric Student Newman–Keuls test,10 when indicated. Multiple Fisher exact tests were used to compare the numbers of patients with a complete motor block, and the numbers of patients requiring ephedrine or atropine. To adjust for multiple comparisons in these tests, the sequentially rejective Bonferroni–Holm method was applied. A P<0.05 was considered significant.


    Results
 Top
 Abstract
 Introduction
 Methods
 Results
 Discussion
 References
 
Patient characteristics are presented in Table 1. Neural block characteristics are summarized in Table 2. In all patients symmetrical analgesia levels were obtained. Median upper analgesia levels vs time are presented in Figure 1. The increase in the upper analgesia level after placing the patient in the supine position was similar in groups 1–3, but smaller in group 4 (P<0.05). Twenty minutes after injection, the upper levels were lower in patients from group 4 than in patients from the other groups (P<0.05; Fig. 2, Table 2). However, the increase in the upper analgesia levels beyond 20 min was larger in group 4 than in the groups 1–3 (P<0.05). Consequently, the highest recorded analgesia levels did not differ between the groups, but were reached later in group 4 (P<0.05; Fig. 3, Table 2). The number of patients with complete motor block did not differ between the groups.


View this table:
[in this window]
[in a new window]
 
Table 1 Patient characteristics. Data are mean (SD) (range) or frequencies, as appropriate
 

View this table:
[in this window]
[in a new window]
 
Table 2 Neural block characteristics. Analgesia data are median (95% confidence interval); motor block data are frequencies (%). {ddagger}Data in group 1 are increases after 5 min (analgesia levels were not assessed at 2 min). *P<0.05 compared with groups 1, 2, and 3, {dagger}P<0.05 compared with group 1
 


View larger version (20K):
[in this window]
[in a new window]
 
Fig 1 Median upper analgesia levels vs time in the four study groups. Medians are corrected for tied observations.

 


View larger version (16K):
[in this window]
[in a new window]
 
Fig 2 Individual analgesia levels 20 min after the injection. Horizontal lines represent median levels. Medians are corrected for tied observations.

 


View larger version (16K):
[in this window]
[in a new window]
 
Fig 3 Individual highest levels of analgesia. Horizontal lines represent median levels. Medians are corrected for tied observations.

 
Analgesia was adequate for surgery in all patients. Changes in SAP and HR were similar in all groups (Table 3). One patient in group 2 and four patients in group 3 required ephedrine for treatment of hypotension and one patient in each of the groups required atropine for bradycardia.


View this table:
[in this window]
[in a new window]
 
Table 3 Haemodynamic changes and ephedrine and atropine requirements. {dagger}Data are mean (95% confidence interval); {ddagger}data are median (95% confidence interval)
 

    Discussion
 Top
 Abstract
 Introduction
 Methods
 Results
 Discussion
 References
 
The present study showed that a 20-min period of sitting is not sufficient to restrict the maximum cephalad spread of sensory analgesia when using 3 ml of 0.5% bupivacaine in 8% glucose. The period of sitting (2–20 min) after a subarachnoid injection of a hyperbaric bupivacaine solution appears to have little, if any, influence on the ultimately attained analgesia levels in elderly patients. This suggests that upward spread of local anaesthetic via the cerebrospinal fluid occurs when the patient is repositioned from the sitting to the supine position, even after prolonged periods of sitting.

With shorter periods of sitting (<=10 min), the upper analgesia level increased by approximately four segments after placing the patient in the supine position. With a longer period of sitting, for example 20 min, the average increase was only two segments. This suggests that with time less local anaesthetic is available for upward spread. This presumably is the result of binding of local anaesthetic to tissue structures within the subarachnoid space, in particular spinal cord.

The effect of the period of sitting on the spread of sensory block following subarachnoid administration of a hyperbaric anaesthetic solution has been studied previously by Povey and colleagues.7 Their study showed that, irrespective of the period of sitting (2–25 min), analgesia levels increased several segments after the patient had been put into the supine position. Subsequent positioning in a 15° head-down position resulted in a further increase of the analgesia levels by approximately two to three segments. On the other hand, Sinclair and colleagues11 reported that a 15° head-down tilt had minimal effect on the cephalad spread of analgesia. In that study, however, patients were positioned in the head-down position immediately after the injection and were maintained in that position for only 10 min before being placed into the supine horizontal position. Taken together, the observations of both Povey and colleagues and Sinclair and colleagues suggest that the ultimately achieved upper analgesia level is mainly dependent upon the final position of the patient. This is further substantiated by another study of Povey and colleagues,8 which showed that sensory block following injection of a hyperbaric bupivacaine solution may still extend rostrally if the patient is placed supine after sitting for as long as 60 min after subarachnoid injection. This indicates that the ‘fixation time’ of a hyperbaric solution takes at least 60 min with bupivacaine. In both studies of Povey and colleagues, the increase in the highest level of analgesia was considerably larger than in our study. In part, this may be related to differences in the dose of bupivacaine administered, which amounted to 3 ml of 0.5% bupivacaine in this study and 4 ml of 0.5% bupivacaine in the studies of Povey and colleagues.

Similarly, it has been demonstrated that changes in position can alter the spread of sensory block for at least 1 h following subarachnoid administration of a hypobaric lidocaine solution for perirectal surgery.12 Dermatomal levels remained low (T11–L5) while the patients were in the prone (jackknife) position with the head down at 15° from horizontal, but increased two to six dermatomes if the patient was placed in a sitting position in the recovery room after surgery.

Positional changes may also extend the sensory block after subarachnoid administration of glucose-free bupivacaine which is slightly hypobaric at body temperature.13 The level of sensory block increased up to four segments when the patient was placed 30° head up after lying supine for 80–115 min after the injection of glucose-free bupivacaine. This is probably related to migration of unbound bupivacaine within cerebral spinal fluid (CSF). If a true isobaric solution is injected, the epicentre of the local anaesthetic concentration in CSF remains at the site of injection regardless of the position of the patient during and after the injection. This was demonstrated clinically by Wildsmith and colleagues, who studied the effects of posture on the spread of isobaric tetracaine and concluded that posture should not be used to control the spread of isobaric solutions.9

Several studies have shown that analgesia levels obtained after subarachnoid injection of a hyperbaric local anaesthetic solution are approximately three to four spinal segments higher in elderly compared with young adult patients.13 The same presumably holds for levels of sympathetic block that are associated with analgesia levels, but are generally two to four segments higher. Conse quently, the highest levels of sympathetic block are often in the upper thoracic region in elderly patients, which may explain the higher frequency of cardiovascular side effects in elderly compared with young adult patients.4 5 Factors that contribute to the more extensive block in the elderly include gradual degeneration of the central and peripheral nervous system,14 15 changes in the anatomical configuration of the lumbar and thoracic spine,16 and possibly a reduction in the volume of the cerebrospinal fluid.6

Recently, we demonstrated that injecting hyperbaric bupivacaine at a lower (L4–L5) than the usual (L3–L4) lumbar interspace did not reduce cephalad spread of local anaesthetic and did not limit the highest analgesia levels.17 In that study, as well in this study, there was a considerable inter-individual variation in the highest level of analgesia. These observations are in keeping with earlier reports on the spread of analgesia following subarachnoid administration of hyperbaric bupivacaine, in particular in elderly patients.2 3 Because of this profound inter-individual variability, the predictability of the analgesia levels that will be reached in an individual patient is low.2 3 17

In conclusion, this study has demonstrated that during spinal anaesthesia with a hyperbaric bupivacaine solution the period of sitting has little, if any, influence on final analgesia levels and on haemodynamic changes in elderly patients. These results suggest that the use of posture does not allow as much control over the spread of a hyperbaric solution as is thought.


    References
 Top
 Abstract
 Introduction
 Methods
 Results
 Discussion
 References
 
1 Racle JP, Benkhadra A, Poy JY, Gleizal B. Spinal analgesia with hyperbaric bupivacaine: influence of age. Br J Anaesth 1988; 60: 508–14[Abstract]

2 Veering BT, Burm AGL, Spierdijk J. Spinal anesthesia with hyperbaric bupivacaine: effects of age on neural blockade and pharmacokinetics. Br J Anaesth 1988; 60: 187–94[Abstract]

3 Veering BT, Burm AGL, Vletter AA, Van den Hoeven RAM, Spierdijk J. The effect of age on systemic absorption and systemic disposition of bupivacaine after subarachnoid administration. Anesthesiology 1991; 74: 250–7[ISI][Medline]

4 Carpenter RL, Caplan RA, Brown DL, Stephenson C, Wu R. Incidence and risk factors for side effects of spinal anesthesia. Anesthesiology 1992; 76: 906–16[ISI][Medline]

5 Chamberlain DP, Chamberlain BDL. Changes in the skin temperature of the trunk and their relationship to sympathetic blockade during spinal anesthesia. Anesthesiology 1986; 65: 139–43[ISI][Medline]

6 Greene NM. Distribution of local anesthetic solutions within the subarachnoid space. Anesth Analg 1985; 64: 715–30[ISI][Medline]

7 Povey HM, Albrecht Olsen P, Pihl H. Spinal analgesia with hyperbaric 0.5% bupivacaine: effects of different patient positions. Acta Anaesthesiol Scand 1987; 31: 616–9[ISI][Medline]

8 Povey HMR, Jacobsen J, Westergaard-Nielsen J. Subarachnoid analgesia with hyperbaric 0.5% bupivacaine: effect of a 60-min period of sitting. Acta Anaesthesiol Scand 1989; 33: 295–7[ISI][Medline]

9 Wildsmith JAW, McClure JH, Brown DT, Scott DB. Effects of posture on the spread of isobaric and hyperbaric amethocaine. Br J Anaesth 1981; 53: 273–8[Abstract]

10 Zar JH. Biostatistical Analysis, 2nd Edn. Englewood Cliffs, New Jersey: Prentice Hall Inc., 1984; 20–3, 199–201

11 Sinclair CJ, Scott DB, Edström HH. Effect of the Trendelenberg position on spinal anaesthesia with hyperbaric bupivacaine. Br J Anaesth 1982; 54: 497–500[Abstract]

12 Bodily MN, Carpenter RL, Owens BD. Lidocaine 0.5% spinal anesthesia: a hypobaric solution for short-stay perirectal surgery. Can J Anaesth 1992; 39: 770–3[Abstract]

13 Niemi L, Tuominen M, Pitkänen M, Rosenberg PH. Effect of late posture change on the level of spinal anaesthesia with plain bupivacaine. Br J Anaesth 1993; 71: 807–9[Abstract]

14 Bromage PR. Epidural Analgesia. Philadelphia, Pennsylvania: WB Saunders, 1978; 40–2

15 Dorfman LJ, Bosley TM. Age-related changes in peripheral and central nerve conduction in man. Neurology 1979; 29: 38–44[Abstract]

16 Ericksen MF. Aging in lumbar spine. II. L1 and L2. Am J Phys Anthropol 1978; 48: 241–5[ISI][Medline]

17 Veering BTh, Ter Riet PM, Burm AGL, Stienstra R, Van Kleef JW. Spinal anaesthesia with 0.5% hyperbaric bupivacaine in elderly patients: effect of site of injection on spread of analgesia. Br J Anaesth 1996; 77: 343–6[Abstract/Free Full Text]