6.1 Anaesthetic experience

Patient outcomes are better when perioperative management is undertaken by experienced anaesthetic personnel.^65,92 An Audit Commission report has shown wide variations in practice in the anaesthetic management of hip fracture patients.⁵⁴ In some hospitals, all patients with fractured hip are anaesthetised by an experienced anaesthetist (registrar or above), whereas in others almost half are anaesthetised by an unsupervised senior house officer. The SHFA has shown similar, but less pronounced, variations.¹ Evidence level 3

Anaesthesia should be carried out, or closely supervised, by an anaesthetist with sufficient experience of anaesthesia in elderly patients.

6.2 General vs. regional (spinal/epidural) anaesthesia

The impact of anaesthetic technique on various aspects of outcome of surgery for fractured hip has been assessed in a meta-analysis,⁹³ in systematic reviews^58,94 and other studies.^66,95,96,97

6.2.1 MORTALITY

A meta-analysis of 13 studies, mainly RCTs, showed a reduction in mortality at one month in patients treated with regional (spinal or epidural) anaesthesia, compared with those receiving general anaesthesia (summary odds ratio for mortality 0.67, 95% CI 0.46-0.98).⁹³ However, evaluation of this meta-analysis found that some of the studies had used the same patient population, and that one of the studies was not an RCT.⁵⁸ When this data is excluded, there is still a reduction in mortality at one month in the regional anaesthesia group (7.5% vs. 9.2%), with a relative risk for mortality of 0.68 (95% CI 0.46-0.96) in favour of regional anaesthesia, which was recommended as the anaesthetic technique of choice. A Cochrane review⁹⁴ found that patients receiving regional anaesthesia had a reduced mortality at one month compared with patients receiving general anaesthesia (6.8% vs. 9.4%) with a relative risk of 0.72 (95% CI 0.51-1.00). Neither of these studies detected any statistically significant difference in mortality after one month. Evidence level 1+

The difference in 30 day mortality is of borderline statistical significance and many of the studies included in these reviews are more than 10 years old. Techniques of general anaesthesia have changed in this time and many anaesthetists now supplement general anaesthesia with nerve blocks.⁹⁸ Further study comparing modern general and regional anaesthesia with or without supplementary nerve blocks is required.

However, further weight has been given to the benefits of regional anaesthesia by a systematic review of 141 RCTs involving over 9,500 patients undergoing all types of major surgery, including hip fracture surgery, which found a 30% reduction in 30 day mortality in the patients receiving regional anaesthesia.⁹⁹ Evidence level 1++

6.2.2 MORBIDITY

Aspects of outcome other than mortality have been studied less extensively:

Deep vein thrombosis (DVT)

Several studies have shown a reduction in asymptomatic DVT following spinal anaesthesia, as diagnosed by venography or labelled fibrinogen,^93,100 and this has been reflected by a lower incidence of thromboembolic complications in some studies. Pooled data⁹⁴ show a reduction in asymptomatic DVT from 47% to 30% in patients in the regional anaesthesia groups (relative risk 0.64, 95% CI 0.46-0.86). Evidence level 1++

Pulmonary thromboembolism (PTE)

There is a non-significant reduction (0.64% vs 2.0%, relative risk 0.48, 95% CI 0.18-1.28) in the incidence of fatal PTE in patients undergoing regional anaesthesia.⁹⁴ Evidence level 1++

Hypoxaemia

Hypoxaemia is worse in the first six hours after surgery under general anaesthesia compared with spinal anaesthesia. Thereafter there is no difference between patients treated with either type of anaesthesia.⁹³ Evidence level 2+

Hypotension

The Cochrane review found a non-significant increase in the incidence of hypotension following regional compared with general anaesthesia (34% vs. 26%).⁹⁴ In a study of patients with known ischaemic heart disease, hypotension was more common in patients who had received single shot spinal or general anaesthesia, compared to those who had received an incremental spinal technique using an intrathecal catheter.¹⁰¹ Hypotension was associated with evidence of myocardial ischaemia in such patients. Evidence level 1+

Acute confusional state

A correlation has been demonstrated between acute confusional state and intraoperative hypotension, perioperative hypoxaemia, the use of anticholinergic agents and a history of depression.¹⁰² The development of an acute confusional state does not appear to be associated with any particular anaesthetic technique. Conversely (although it did not examine patients with a fractured hip), one study¹⁰³ found that in elderly patients undergoing general anaesthesia, increasing age, duration of anaesthesia, postoperative infection, a second operation, and respiratory complications, were risk factors for early postoperative cognitive dysfunction, but that hypoxaemia and hypotension were not. Evidence level 2+

Other indicators of morbidity

There appears to be no statistically significant difference in the incidence of postoperative respiratory morbidity, perioperative blood loss, myocardial infarction, congestive cardiac failure, renal failure and cerebrovascular accident following different types of anaesthesia.⁹⁴ Evidence level 1++

Ambulation

There is evidence to suggest that the time to ambulation may be quicker (three days vs. five days, p<0.05) in patients anaesthetised using regional anaesthesia.¹⁰⁴ Evidence level 1+

In summary, in patients who have undergone regional anaesthesia there may be a reduction in mortality at one month, and there appear to be other benefits from regional rather than general anaesthesia, including a significant reduction in the incidence of deep venous thrombosis.

Regional anaesthesia may be considered for patients undergoing hip fracture repair, particularly in those at risk of venous thromboembolic complications.

6.2.3 HEPARINS

The use of regional anaesthesia in patients who have received unfractionated low dose heparin (LDH) and low molecular weight heparin (LMWH) is controversial because of the risk of development of a vertebral canal haematoma.⁸¹ Anti-Xa activity after LMWH peaks 3-4 hours after injection and falls to 50% only after 12 hours.¹⁰⁵ Evidence level 4

Administration of spinal or epidural anaesthesia should be delayed until 10-12 hours after the administration of low molecular weight heparin.

6.2.4 ASPIRIN

There is little or no evidence that aspirin increases the risk of vertebral canal haematoma in patients receiving spinal or epidural anaesthesia,¹⁰⁶ although interactions with other agents such as heparins or warfarins may occur.¹⁰⁷ Evidence level 4

6.3 Peripheral nerve blocks

Discussion of the multiplicity of nerve blocks available to supplement anaesthesia and provide analgesia into the postoperative period is outside the scope of this guideline.

One systematic review found that nerve blocks reduce the quantity of opioid analgesics required in the postoperative period.⁶⁴ Unfortunately, the studies included in the review each examined different outcome measures other than opioid usage and no significant benefits were demonstrable from reduced opioid use. Evidence level 1++

6.4 Fluid balance

Invasive intravascular monitoring is not usually carried out in patients undergoing hip fracture surgery, despite the fact that patients are frequently dehydrated prior to surgery whilst at the same time unable to cope with large volumes of parenteral fluid. A small study of patients undergoing general anaesthesia found the use of an oesophageal Doppler monitor to optimise the intravascular volume status of patients was associated with a more rapid recovery postoperatively and reduced length of stay.¹⁰⁸