18RC1
Regional anaesthesia in the elderly
Bernadette Veering
Department of Anesthesiology, Leiden University Medical Centre, Leiden, the Netherlands
Saturday, 11 June 2011
13:00 - 13:45
Room: G105
There has been a dramatic rise in the elderly population with the number of people aged over 65 increasing three-fold in the last century. The age group that is growing most rapidly includes those aged 85 and over. Consequently this has led to a progressive increase
in the number of surgical interventions in elderly people. It has been estimated that over half of the population aged over 65 years will
require surgical intervention at least once during the remainder of their lives. Regional anaesthetic techniques (peripheral nerve blockade, central neuraxial blockade) are frequently used in elderly patients. This lecture will focus on the impact of age on the clinical and
pharmacological aspects of epidural and spinal anaesthesia in particular, and will be accompanied by an additional discussion of certain
aspects of peripheral nerve blockade.
Age-related changes relevant to regional anaesthesia
Both the central and peripheral nervous system degenerate with advancing age. These changes may have an impact on neural block
characteristics and the pharmacology of local anaesthetic agents. A reduction in the number of neurones within the spinal cord, deterioration of myelin sheaths and connective tissue barriers, changes in the anatomical configuration of the lumbar and thoracic spine, possible
reduction in the volume of cerebrospinal fluid and slowing of the conduction velocity in peripheral nerves, especially the motor nerves, all
contribute to altered nerve block characteristics (dose-response relationship) following epidural and subarachnoid administration of local
anaesthetic agents [1].
After lumbar epidural administration of a given dose (fixed volume and concentration) of a local anaesthetic solution the spinal level
(height) of analgesia increases with advancing age [2-4] and, similarly, following thoracic epidural administration of a fixed dose [5]. This
is due to progressive sclerotic closure of the intervertebral foramina. Epinephrine is used frequently as a part of a test dose to detect
intravascular injection and elderly patients may have a reduced response because the beta-receptor affinity for adrenergic agonists is
diminished [1].
With spinal anaesthesia the extent of the block depends on the baricity of the solution [1]. The effect of age on the maximal height
of spinal analgesia with isobaric solutions is marginal, but with a hyperbaric solution a higher sensory block and a quicker onset time of
motor block have been found in older patients.
Clinical problems
Epidural and spinal anaesthesia may present some problems in elderly patients. Performing epidural and spinal anaesthesia may be
more difficult in elderly patients. It is often not easy to position the elderly patient appropriately because of the anatomical irregularities
that may be found in many old people, particularly curvature or rotation of the spine. Additionally, the intervertebral foramina are narrowed by sclerotic changes and calcification in elderly patients. In advanced age with degenerative disc and joint changes, distortion and
compression of the epidural space are typical. The structure of the ligamentum flavum probably changes into a form that is easily ossified. Increased epidural compliance and decreased epidural resistance, increased residual epidural pressure and progressive sclerotic
closure of the intervertebral foramina with advancing age may all contribute to enhanced epidural spread of local anaesthetic solution in
the elderly.
- 1 -
Hypotension, hypothermia and increased sensitivity to local anaesthetics are serious problems during regional anaesthesia in the
elderly.
Hypotension
Hypotension during spinal and epidural anaesthesia results from sympathetic blockade that leads to vasodilatation and a reduction in
systemic vascular resistance. With an extensive block this may lead to decreased venous return that is the main determinant of hypotension during central neuraxial blockade. Carpenter reported the incidence and risk factors for side-effects of spinal anaesthesia [6]. High
levels of sensory anaesthesia and increasing age appeared to be the two main risk factors for the development of hypotension. High
levels of analgesia were associated with bradycardia and hypotension in elderly patients undergoing epidural anaesthesia [3]. Decreased
cardiac reserves, structural changes in the arterioles and changes in the autonomic nervous system with increasing age may also play
a role. Marked hypotension may be especially harmful to elderly patients with limited cardiac reserve. Preloading with fluids, either crystalloids or colloids did not prevent hypotension after spinal anaesthesia in elderly patients [7]. A combination of fluids and vasopressors
when given in the first 5-10 min (when the block is evolving) seems to be the most effective treatment for hypotension after spinal or
epidural anaesthesia in elderly patients [8].
One of the most effective methods of preventing hypotension is to avoid a high sensory block. Continuous spinal anaesthesia allows
the administration of small incremental doses of local anaesthetics and thus provides a more controllable sensory and sympathetic level.
It is a very effective technique in providing haemodynamic stability in elderly patients undergoing lower extremity surgery [9]. The rationale
for combining local anaesthetics with adjuvant drugs is to use lower doses of each agent and to sustain analgesia with fewer side-effects.
A reduced dose of hyperbaric bupivacaine (7.5 mg) in combination with sufentanil [10] or a small dose of plain bupivacaine (4 mg) in
combination with fentanyl (20 µg) provided reliable spinal anaesthesia for the repair of hip fracture in aged patients with few episodes of
hypotension and little need for vasopressor support [11].
Hypothermia
Elderly patients who undergo spinal or epidural anaesthesia are at increased risk of hypothermia, because a low core temperature
may not initiate autonomic protective responses. Advancing age and high-level spinal blockade are associated with a significant decrease
of thermoregulatory threshold [12]. The shivering threshold is decreased in proportion to the level of spinal blockade because the vasomotor tone is inhibited below the level of spinal block and the greater the proportion of the body that is blocked, the greater the level of
thermoregulatory dysfunction that can be expected.
Sedation
Geriatric patients show an increased sensitivity to benzodiazepine compounds [13]. Smaller doses and a longer period between increments must be used and caution should be used when benzodiazepines are given to geriatric patients as premedication. Elderly patients
are more sensitive to the hypnotic and EEG effects of propofol than are younger persons. Propofol infusion for sedation during spinal
anaesthesia resulted in a delayed recovery time in the elderly patients compared with younger patients [14]. Elderly patients may require
a more prolonged observation period after sedation with propofol.
Pharmacology
Pharmacokinetics of local anaesthetics
Changes in body composition and characteristics of tissues and organs within the body may have an impact on the rate and extent
of systemic absorption, distribution and elimination of local anaesthetics used for regional anaesthesia. Pharmacokinetic or pharmacodynamic changes, which occur with increasing age, may alter the clinical profile of local anaesthetics following a regional anaesthetic.
Changes in the pharmacokinetics may, in part, be responsible for the observed changes in the clinical profile. Epidural absorption studies
with bupivacaine, ropivacaine and levobupivacaine and a spinal absorption study with bupivacaine demonstrated an increased sensitivity in the elderly that does not appear to be related to the impairment of vascular absorption [1, 15]. Therefore, changes in the clinical
- 2 -
profile with epidural and spinal anaesthesia are best explained by anatomical considerations and possibly pharmacodynamic, rather than
pharmacokinetic, changes in the elderly.
The plasma clearance of lidocaine, bupivacaine and ropivacaine decrease with increasing age [15].Taking into account the agerelated decreased clearance of lidocaine, bupivacaine and ropivacaine, the administration of multiple intermittent injections or continuous
epidural infusion can lead to increased accumulation of these agents. Consequently, the potential of developing side-effects, including
toxicity may be enhanced.
Effects of regional anaesthesia on outcome in elderly surgical patients
To demonstrate superiority of one anaesthetic technique above another requires a review of the outcome. The incidence of cardiovascular diseases is high in elderly surgical populations undergoing peripheral vascular surgery of the lower extremity. In this patient population studies have been performed comparing regional with general anaesthesia with respect to postoperative mortality and cardiac morbidity. However, no difference was found in the incidence of cardiac ischaemia in patients who were randomly assigned general, epidural
or spinal anaesthesia combined with postoperative epidural analgesia or general anaesthesia with on-demand opioid analgesia (PCA)
[16]. Postoperative outcomes were not influenced by the intra-operative and postoperative anaesthetic regimen. Thus, peri-operative
care, rather than a specific anaesthetic regimen, may be the most important factor in determining outcome after major vascular surgery.
The early administration of continuous epidural analgesia was associated with a lower incidence of pre-operative adverse cardiac
events in elderly patients with hip fracture who have, or are at risk of, coronary artery disease [17]. Although the study group was small,
the results warrant further study of pre-operative analgesia in this population.
It appears that postoperative thoracic epidural analgesia is superior to lumbar epidural analgesia in reducing postoperative myocardial
infarction [18]. This suggests that in high-risk cardiac patients, thoracic epidural postoperative analgesia is warranted and should be used
more widely.
Many individual controlled studies comparing regional anaesthesia with general anaesthesia have lacked the statistical power to provide a conclusive answer as to which gives the better outcome in terms of morbidity and mortality. In addition most controlled trials have
failed to demonstrate that either regional anaesthesia or general anaesthesia is clearly superior in terms of outcome in elderly patients.
It seems that the probability of a serious respiratory or haemodynamic complication after surgery in elderly patients, as in young adults,
is largely determined by the nature of the surgery and by the patient’s general state. Further large, well-designed RCTs are necessary to
draw firm conclusions on the effect of anaesthetic techniques on long-term outcome after surgery in elderly patients. Further evaluation
of the clinical and specific pharmacological aspects of regional anaesthetic procedures in older people is still required.
Postoperative cognitive function
Early postoperative cognitive dysfunction (POCD), confusion and delirium are common after major surgery in the elderly. Regional
anaesthesia reduced the incidence of POCD in the first postoperative week [19]. However, no significant difference was found in the
incidence of cognitive dysfunction three months after either general or regional anaesthesia in elderly patients.
Peripheral nerve blockade
Peripheral nerve blocks are frequently used in elderly patients as a satisfactory supplementary analgesic technique for upper limb
trauma, hip and knee surgery. Few studies have been performed investigating peripheral nerve block characteristics in elderly patients.
Sensory and motor blocks lasted approximately 2.5 times longer in the elderly compared with young patients after a brachial plexus block
with ropivacaine [20], as well after a sciatic nerve blockade with mepivacaine [21]. Further studies are indicated to investigate the effect
of age on the characteristics of other peripheral blocks. Combined, pharmacokinetic-pharmacodynamic studies will enable practitioners
to predict the dose requirement of local anaesthetics for older patients more accurately.
- 3 -
Key learning points
• Older patients experience slightly higher spinal levels of sensory and motor blockade following epidural and spinal anaesthesia and
are also at somewhat greater risk of hypotension. Thus, bolus doses of local anaesthetic should be reduced in elderly patients in
order to limit side-effects.
• The duration of analgesia and motor blockade last longer in the elderly after peripheral nerve blocks.
• The clearance of bupivacaine, ropivacaine and lidocaine decrease with age. Consequently, infusion rates or top-up bolus doses
may need to be adjusted.
• Regional anaesthesia has several beneficial effects for elderly patients, including reduced blood loss, better peripheral vascular
circulation, suppression of the surgical stress response and better postoperative pain control.
• Most controlled trials have failed to demonstrate that either regional or general anaesthesia is clearly superior in terms of outcome
in elderly patients.
References
1. Tsui BC, Wagner A, Finucane B. Regional anaesthesia in the elderly: a clinical guide. Drugs Aging 2004; 21: 895-910.
2. Veering BT, Burm AGL, Van Kleef JW, Hennis PJ, Spierdijk J. Epidural anesthesia with bupivacaine-effects of age on neural
blockade and pharmacokinetics. Anesthesia and Analgesia 1987; 66: 589-94.
3. Simon MJ, Veering BT, Stienstra R, van Kleef JW, Burm AG. The effects of age on neural blockade and hemodynamic changes
after epidural anesthesia with ropivacaine. Anesthesia and Analgesia 2002; 94: 1325–30.
4. Simon MJ, Veering BT, Stienstra R, van Kleef JW, Burm AG. Effect of age on the clinical profile and systemic absorption and
disposition of levobupivacaine after epidural administration. British Journal of Anaesthesia 2004; 93: 512–20.
5. Hirabayashi Y, Shimizu R. Effect of age on extradural dose requirement in thoracic extradural anaesthesia. British Journal of
Anaesthesia 1993; 71: 445–6.
6. Carpenter RL, Caplan RA, Brown DL, Stephenson C, Wu R. Incidence and risk factors for side effects of spinal anesthesia.
Anesthesiology 1992; 76: 906–12.
7. Buggy D, Higgins P, Moran C, et al. Prevention of spinal anesthesia-induced hypotension in the elderly: comparison between
preanesthetic administration of crystalloids, colloids and no prehydration. Anesthesia and Analgesia 1997; 84: 106-10.
8. Critchley LAH. Hypotension, subarachnoid block and the elderly patient. Anaesthesia 1996; 51: 1139-43.
9. Minville V, Fourcade O, Grousset D, et al. Spinal anesthesia using single injection small-dose bupivacaine versus continuous
catheter injection techniques for surgical repair of hip fracture in elderly patients. Anesthesia and Analgesia 2006; 102: 1559-63.
10. Olofsen E, Burm AGL, Simon M, Veering BT, van Kleef J, Dahan A. Population pharmacokinetic-pharmacodynamic modeling of
epidural anesthesia. Anesthesiology 2008; 109: 664-74.
11. Ben-David B, Frankel R, Arzumonov T, Marchevsky Y, Volpin G. Minidose bupivacaine-fentanyl spinal anesthesia for surgical
repair of hip fracture in the aged. Anesthesiology 2000; 92: 6-10.
12. Frank SM, El-Rahmany HK, Cattaneo CG, et al. Predictors of hypothermia during spinal anesthesia. Anesthesiology 2000; 92:
1330-4.
13. Jacobs R, Reves JG, Marty T, et al. Ageing increases pharmacodynamic sensitivity to the hypnotic effect of midazolam.
Anesthesia and Analgesia 1994; 80: 143-8.
14. Shinozaki M, Usui Y, Yamaguchi S, Okuda Y, Kitajima T. Recovery of psychomotor function after propofol sedation is prolonged in
the elderly. Canadian Journal of Anaesthesia 2002; 49: 927-31.
15. Simon MJ, Veering BT. Factors affecting the pharmacokinetics and neural block characteristics after epidural administration of
local anaesthetics. European Journal of Pain Supplements 2010; 4: 209-18.
16. Norris EJ, Beattie C, Perler BA, et al. Double-masked randomized trial comparing alternate combinations of intraoperative
anesthesia and postoperative analgesia in abdominal aortic surgery. Anesthesiology 2001; 95: 1054–67.
17. Matot I, Oppenheim-Eden A, Ratrot R, et al. Preoperative cardiac events in elderly patients with hip fracture randomized to
epidural or conventional analgesia. Anesthesiology 2003; 98: 156-63.
18. Beattie W, Badner N, Choi P. Epidural analgesia reduced postoperative myocardial infarction: a meta-analysis. Anesthesia and
Analgesia 2001; 93: 853- 8.
19. Rasmussen LS. Postoperative cognitive dysfunction: incidence and prevention. Baillieres Best Practice & Research in Clinical
Anaesthesiology 2006; 20: 315–30.
20. Paqueron X, Boccara G, Bendahou M, Coriat P, Riou B. Brachial plexus nerve block exhibits prolonged duration in the elderly.
Anesthesiology 2002; 97: 1245-9
21. Hanks RK, Pietrobon R, Steele SM, et al. The effect of age on sciatic nerve block duration. Anesthesia and Analgesia 2006; 102:
588-92.
- 4 -