REGIONAL VS. GENERAL ANAESTHESIA

IN TREATMENT OF HIP FRACTURE

CONTENTS

Why this topic? Why choose this topic? General information Regional anaesthesia and its modes of usage Common anaesthetic agents used How do the anaesthetics work Comparing the side effects of the different types of

anaesthesia Differences seen and their likely explanation Comparison mortality rates Cochrane evidence Patient’s perspectives Anaesthetist’s perspectives References

WHY THIS TOPIC? Hip fracture management forms large bulk of work in

orthopaedics

Prediction to be 6.3 million cases globally by 2050, Approx 80,000 per year in UK (65,000 in over 65’s)

Anaesthesia is of prime importance in the active management

Mainly affects the elderly female population with intercurrent illnesses- importance of the appropriate anaesthesia

WHAT IS ANAESTHESIA ?

‘Anaesthesia aims to ensure hypnosis, amnesia, analgesia, relaxation of skeletal muscles with loss of control of reflexes of the autonomic nervous system’

GENERAL INFORMATION Regional anaesthesia

Applicable large parts of the body

Divided into central and peripheral

Neuraxial blocks – epidural anaesthesia and spinal anaesthesia

Peripheral - plexus blocks and single nerve blocks

Regional anaesthesia- spinal injection of LA or epidural , often used with sedatives

GA induced and maintained by a number of drugs- dependent on the anaesthetist preference with appropriate airway

REGIONAL ANAESTHESIA

Epidural Spinal

REGIONAL ANAESTHESIA FOR NOF REPAIR

Comparing psoas compartment catheter and epidural catheter

Psoas compartment catheter Epidural catheter

COMMON ANAESTHETIC AGENTS FOR HIP SURGERY

Spinal anaesthesia in hip surgery- lidocaine, mepivacaine, bupivacaine, ropivacaine,

tetravacaine

Lumbar epidural anaesthesia in hip surgery – 2- Chloprocaine, lidocaine, etidocaine, mepivacaine,

bupivacaine, ropivacaine

General anaesthetic – with inhalational, intravenous anaesthetic agents

HOW DO LOCAL ANAESTHETICS WORK?

Reversible interruption of the conduction of impulses in peripheral nerves

Blockade of Sodium channels- impairing sodium flux across the membrane, to some extent on Potassium channels also

Main effect – local decrease in rate and degree of depolarisation- threshold potential not reached and electrical impulse not propagated

No effect on the resting or threshold potential, however refractory period and repolarisation may be prolonged.

HOW DO LOCAL ANAESTHETICS WORK?

HOW DO GENERAL ANAESTHETICS WORK?

The exact mechanism is not known despite of its usage for more than 150 yrs.

Structure is related to ether, the original anaesthetic

Primary site of action is on the CNS- inhibit nerve transmission- reduction in nerve transmission at the synapses

Potentiated by 2 main receptors;

GABA-A- Potentiated by halothane, etomidate and propofol NMDA- inhibited by ketamine

Inhalation anaesthetics e.g. sevoflurane- main action on brain

SIDE EFFECTS OF ANAESTHESIA Epidural

Hypotension- commonest side effect, esp imp for cardio problems High epidural block- unintentional Local anaesthetic toxicity- another unintentional side effect Regional anaesthesia- impaired coagulation or poor patient

cooperation Rarely becomes a fully spinal anaesthetic

Spinal

Length of surgery Headache- commonest complaint amongst young patients Rarely- infection

General Anaesthesia

Usually well tolerated Rarely can lead to stroke or myocardial infarction Aspiration – prevented by endotracheal tube insertion

EVIDENCE COMPARING REGIONAL VS. GENERAL

Meta-analysis by Urwin S.C et al.

Previous meta-analysis of 11 trials showed no overall advantages in one anaesthetic over the other

In terms of risk of DVT and survival at one month- Regional better than General anaesthesia

Results not applicable to all settings due to underlying morbidity not being considered

DIFFERENCES SEEN AND LIKELY EXPLANATION

Risk of DVT

Risk of intraoperative hypotension – no significant reduction with either method

Risk of pulmonary embolism(fatal and non-fatal)- reduced incidence of fatal PE and major thromboembolism with regional

Risk of other conditions- pneumonia, urinary retention,CCF, post-operative vomiting and nausea- no significant differences seen

EXPLANATION OF DVT

Spinal group risk of DVT – 30% GA group- 47%

N.B- venography was used in the cases in which patients had DVT

Reduced sympathetic tone to the lower limbs with increased venous blood flow

Alteration in viscosity and coagulability of blood- regional anaesthesia

OTHER DIFFERENCES SEEN

GA associated with small but significant reduction in the length of the operation

Non-significant tendency for greater confusion following GA

Reduced tendency of CVA after GA is due to a more stable perioperative blood pressure

IV therapy+ vasoconstrictor agents during regional anaesthesia could reduce the adv of GA

Regional anaesthesia has marginal advantages

MORTALITY AND MORBIDITY RATES

Mortality - important post-operative concerns

Flawed methodology in studies included in Cochrane analysis

Valentin et al.- 1968 prospective study looking at the mortality of 578 patients post-op repair of NOF

30 days after surgery the mortality was 6% -spinal and 8%- general anaesthesia

6months to 2 years post-op- the mortality was identical

No differences with respect to ambulation and discharge

COMPARISON OF MORBIDITY CONTD.

Estimated blood loss was smaller (P < 0.05) in patients receiving spinal anaesthesia

high short-term mortality was related to age, male sex, and trochanteric fracture

long-term mortality was related to male sex and high ASA scores.

COCHRANE EVIDENCE Cochrane analysis done in 2009

Primary outcome was mortality

8 trials decreased mortality at one month with regional anaesthesia 6.9% vs. 10.0% with general anaesthesia

Reduced risk of DVT; Regional (30%) versus general (47%)

Regional assoc with reduced risk of acute postoperative confusion 9.4 % vs. 19.2 %

Flawed methodology- biased sample of patients

PATIENT’S PERSPECTIVE Awareness is of the main concern that patients have

Mashour et al. 2009 – no statistical difference in intraoperative awareness

Intraoperative awareness complaints in GA 0.023% vs. Regional anaesthesia 0.03%

Complete unconsciousness is often the expectation of the patient

Often the communication between anaesthetist and patient is seen to be inadequate in patient’s experience

Rehabilitation is often seen to be quicker with regional anaesthesia when compared with general anaesthesia

ANAESTHETISTS’ PERSPECTIVE‘One of the hardest anaesthetic lists to do’- CT2 Anaesthetist

The main reason being the comorbidities present in the patients

This makes monitoring of the patient challenging

The final decision is up to to the anaesthetist in terms of the route of administration

Donati et al. BJA 2004 - operative risk of 4000 patients.

The risk for ASA (American Society of Anaesthesiologists) 4 , Age>70,

Elective surgery was 3.7 %

Urgent/emergency it was as high as 16.7%

CONCLUSIONS There are various methods of

anaesthesia for the repair of hip fracture

Better trials with the unbiased sample, and better follow up is needed

Various factors determine the chosen method- patient, anaesthetist and surgeon

All aim for early patient mobilisation following operation

REFERENCES1. Melton Hip fractures; a worldwide problem today and tomorrow

Bone 1993;14 (Suppl. 1): S1-8

2. General versus regional anaesthesia for hip fracture surgery: British Journal of Anaesthesia 84 (4): 450–5 (2000).

3. Mashour GA, Wang L, Turner CR, Vandervest JC, Shanks A, Tremper KK. A retrospective study of intraoperative awareness with methodological implications. Anesth Analg 2009;108:521–6

4. N. Valentin, M.D.,B. Lomholt, M.D., J. S. Jensen, DR MED. SC., N. Hejgaard M.D. and S. Kreiner, Cand. Stat. Spinal or General Anaesthesia for surgery of the fractured hip? A Prospective Study of Mortality in 578 Patients. Br. J. Anaesth. (1986)

5. Dr K Balakrishnan ; Care of the patient with fracture neck of femur for non-emergency surgery.

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