Focus on: Day case
Spinal anaesthesia: The saviour of day surgery?

https://doi.org/10.1016/j.cacc.2007.07.004Get rights and content

Summary

Although commonly used in inpatients, spinal anaesthesia is often a less popular choice for day cases. This may be for historical reasons, but also because of concerns over delayed recovery and adverse effects. Nevertheless, spinal anaesthesia has many advantages and may be an essential measure if day surgery is to be made available to patients with more severe co-existing pathologies.

To be suitable for day surgery, spinal anaesthesia must be modified to reduce the extent and duration of motor block while retaining a useful degree of analgesia. This involves the combination of a low dose of local anaesthetic with an analgesic adjuvant, usually an opioid. This chapter will review some of the wide variety of regimens which have been described. While each have their specific advantages, the addition of 10 μg of fentanyl to 5 mg of hyperbaric bupivacaine made up to a total volume of 3 ml with saline is a simple regimen which will prove suitable for the majority of cases.

Spinal anaesthesia provides good postoperative pain relief and minimises postoperative nausea. With an appropriate technique, discharge should be possible within 3–4 h. Urinary retention is a possible complication, but should be rare unless an excessive opioid dose is used, while post dural-puncture headache can be limited to 1% or less by the use of suitable spinal needles. Low dose spinal anaesthesia, which also provides excellent haemodynamic stability, can significantly extend the population of patients suitable for day surgery.

Introduction

Spinal anaesthesia is commonly used for inpatients in the United Kingdom (UK), but it remains relatively rare in the day case setting, the reasons for which may be predominantly historical. The rapid development of day surgery in the late 1980s and early 1990s was largely concerned with high volume, comparatively minor procedures on carefully selected and relatively fit patients. There were new hypnotic agents available, including propofol, sevoflurane and desflurane, which were well suited to day case general anaesthesia. The growing popularity of the laryngeal mask airway also helped to ensure that day surgery patients enjoyed rapid recovery with minimal side effects.

Times have changed however, and both the population now presenting for day surgery, and the procedures that can be carried out on a day stay basis, have been transformed. The Department of Health has proposed that 75% of all elective surgery could be carried out on a day case basis.1 If this is to be achieved, anaesthetists must re-examine their selection criteria and consider whether general anaesthesia is always the best choice for their patients. Some procedures now being moved into the day case arena are potentially associated with significant postoperative pain, for example lower limb orthopaedic surgery. Spinal anaesthesia (and other forms of regional techniques) has much to offer in management of early postoperative pain and hence reduction of postoperative morbidity. The British Association of Day Surgery (BADS) has actively promoted the wider use of spinal anaesthesia in day surgery.2

There is a wealth of recent literature on the subject of spinal anaesthesia for ambulatory surgery, the vast majority of which comes from outside of the UK. Studies of interest include the use of bupivacaine, levo-bupivacaine, ropivacaine, and chloroprocaine. This article will therefore include a discussion of local anaesthetic drugs and adjuncts which have not been licensed for intrathecal use in the UK. In fact, only two local anaesthetic agents are specifically indicated for subarachnoid injection in the UK and these are 0.5% hyperbaric bupivacaine and 0.5% ‘plain’ levo-bupivacaine. However, plain bupivacaine is also in use and it is common practice for anaesthetists to use other drugs outside of the licensed indication, including for example intrathecal fentanyl. Lidocaine is also still used occasionally although its popularity has declined because of the association with transient neurological syndrome (TNS). Ropivacaine is available in the UK but at the present time indications on the datasheet do not include intrathecal administration. Chloroprocaine on the other hand is not available in the UK but will be included in the discussion because it has a clinical profile which is very favourable for ambulatory spinal use.

Published studies include both hyperbaric and ‘plain’ solutions, diluted with saline or cerebrospinal fluid, or undiluted, with or without fentanyl. Generally speaking, plain or hypobaric solutions tend to spread unpredictably whereas the spread of the block obtained using hyperbaric solutions can be controlled to some degree using the patient's posture and speed of injection. The addition of fentanyl will make all local anaesthetic preparations more hypobaric3 and hence may affect spread. In general, the dose of local anaesthetic is considered to be the main determinant of the duration of the block4 although the duration may also be prolonged if the spread is restricted for the same dose of local anaesthetic, at least using hyperbaric bupivacaine.5

Following on from this, there are two main methods of modifying conventional spinal anaesthesia for day case patients:

  • Reduce the dose of local anaesthetic by careful addition of opioids or clonidine, with the aim of producing a ‘selective spinal anaesthetic’; that is, the sensory nerves are affected to a greater degree than the motor nerves.

  • Restrict the spread of local anaesthetic using drug baricity and injection technique so that only selected nerve roots are affected, for example in a unilateral or saddle block.

Some papers describe techniques that employ a combination of both of these approaches. The two crucial outcomes in any study of practical day case spinal anaesthesia are:
  • The adequacy of anaesthesia for the surgery being performed.

  • The time from spinal injection to home readiness.

The latter is not always directly related to the duration of motor block and, although Bromage scores are usually used to assess motor block, a Bromage score indicating complete motor recovery is not synonymous with ability to mobilise. The ability to safely walk, and hence readiness for discharge, requires balance and co-ordination in addition to motor power and tends to be delayed for some time after full return of motor function. In an interesting study from Toronto, Imarengiaye and colleagues used a ‘computerised force platform’ to objectively assess balance in ASA 1 and 2 patients who had received intrathecal bupivacaine 5 mg plus fentanyl 10 μg for perineal procedures.6 They concluded that “clinical return of motor function occurred much earlier than the recovery of functional balance”. This is an important consideration in all patients but the ability to walk safely may be even further delayed in patients who have had lower limb surgery or whose balance is already impaired by age or high body mass index.

Section snippets

Bupivacaine

Frustratingly for the day case anaesthetist, individual responses to small doses of intrathecal bupivacaine are highly variable. However, some basic techniques for using ‘low-dose’ bupivacaine have been established.

In 1997, Ben-David and colleagues showed that adding 10 μg of fentanyl to 5 mg bupivacaine (1 ml 0.5% hyperbaric bupivacaine), improved the quality of anaesthesia for knee arthroscopy without delaying discharge.7 Their technique included addition of saline to the bupivacaine so that the

Assessing recovery

Whilst the speed of recovery and ultimately home-readiness is of great importance, the quality of the recovery period is also worth examining. Whilst the incidence and severity of pain and postoperative nausea and vomiting (PONV) may be improved, there are also some troublesome side effects of spinal anaesthesia; acute urinary retention and post dural-puncture headache.

Selection criteria for day surgery

Fitness for general anaesthesia has been used to help select patients for day surgery, and many units continue to reject patients with significant co-morbidities. However, if general anaesthesia can be avoided, some of these patients can also enjoy the benefits of day surgery. This will include patients with significant respiratory disease, including sleep apnoea, gastro-oesophageal reflex, obesity and diabetes. The remarkable cardiovascular stability seen with the low-dose techniques described

Summary

In contrast to the USA and Europe, spinal anaesthesia remains uncommon in UK day surgery practice. Nevertheless, this rapidly developing area of research includes the use of drugs and techniques which are readily available in the UK. Selective spinal anaesthesia and the use of restricted blocks are adaptations of conventional spinal techniques that are especially suitable and their widespread introduction in the UK would make a significant impact on the number of patients who could be treated

References (27)

  • A.M. Korhonen et al.

    Intrathecal hyperbaric bupivacaine 3 mg+fentanyl 10 microg for outpatient knee arthroscopy with tourniquet

    Acta Anaesthesiol Scand

    (2003)
  • S. Goel et al.

    Intrathecal fentanyl added to intrathecal bupivacaine for day case surgery: a randomized study

    Eur J Anaesthesiol

    (2003)
  • A. Gupta et al.

    Low-dose bupivacaine plus fentanyl for spinal anesthesia during ambulatory inguinal herniorrhaphy: a comparison between 6 and 7.5 mg of bupivacaine

    Acta Anaesthesiol Scand

    (2003)
  • View full text