when not to block

When not to block William Harrop-Griffiths

Consultant Anaesthetist, St Mary’s Hospital, London Honorary Senior Lecturer, Imperial College, London

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St Mary’s Hospital, Paddington, London

When not to block

William Harrop-Griffiths Consultant Anaesthetist, St Mary’s Hospital, London Honorary Senior Lecturer, Imperial College, London

“There are no patchy blocks with propofol!”

The non-regional anaesthetist

“I wouldn’t do a regional anaesthetic on someone who uses their arm to earn a living”



For them, every day of their life is a time not to block

For those of us who know how to block

When not to block

Contra-indications

Regional Anaesthesia William Harrop-Griffiths

Consultant Anaesthetist, St Mary’s Hospital, London Honorary Senior Lecturer, Imperial College, London

Contra-indications to

Contra-indications

Absolute

Relative

Absolute contra-indications

• Patient refusal

• Local sepsis

• Allergy

Relative contra-indications

• Spinal

• Specific

• Generic

Spinal contraindications • Hypovolaemia

• Cardiac valvular stenosis

• Spinal abnormalities - tumour, spina bifida, surgery

• Includes blocks that sometimes become spinal

• Epidural

• Paravertebral

• Lumbar plexus

Specific situations

• Try not to block both phrenic nerves

• Try not to block three or more limbs

Generic relative contraindications • Paediatric, combative and demented patients

• Systemic sepsis

• Abnormality of anatomy

• Abnormality of coagulation

• Abnormality of nerves

• Where analgesia might mask the pain of ischaemia caused by compartment syndrome

Summary • There is very little evidence available (in

the form of hard data) to inform practice

• This is both good and bad

• Good because it gives sensible clinicians licence to do what is sensible

• Bad because it makes the ground fertile for “expert opinion”

Systemic sepsis

Question

• Is a PNB safer than a CNB in the septic patients?

• No real answer but my answer is:

• I would rather have an infected sciatic nerve than purulent meningitis

• But on balance, I would rather have neither

Summary • There is little hard evidence to inform

practice

• The risk is low

• There are some who will avoid RA in patients with evidence of systemic sepsis

• Modify the risk by giving antibiotics

• If RA offers particular advantage, the patient with capacity may agree to take a (very slightly increased) risk

Coagulopathy

Don’t too much about the exact

numbers

stress

Obstetric anaesthetist asked to do an epidural

12:01 h Time after last prophylactic dose of enoxaparin

stress

11:59 h

Obstetric anaesthetist asked to do an epidural Time after last prophylactic dose of enoxaparin

stress

Risk is not binary

It is a spectrum

The platelet game • 32-year-old ASA 2 patient

• Mild NSAID-sensitive asthma

• Elective, infra-umbilical abdominal surgery

• Would you be happy to do a spinal?

Platelets 100 x 109.l-1



• Elective LSCS




• Morbidly obese


• Elective LSCS




• Morbidly obese

• Known difficult intubation


• Elective LSCS



The platelet game


• 32-year-old ASA 2 patient

• Morbidly obese

• Known difficult intubation


• Elective LSCS


Other games

• INR game

• Hours after the last dose of LMWH game

• Days since the last dose of clopidogrel game

Messages

• Coagulopathy really is a relative contraindication

• Fixed thresholds can and should be flexible

Question

• Most guidelines are about neuraxial blocks

• What about PNBs?

• Are they safer?

PNBs and coagulopathy

• Only 26 reports of significant haemorrhagic complications of PNBs

• 13 patients had normal coagulation

• Majority were deep blocks or superficial perivascular blocks

• One death: clopidogrel + lumbar plexus block

Haematological conditions

One A4 side of advice

• The majority of haematological abnormalities of coagulation are known in advance of anaesthetic intervention

• Most involve a deficiency in a particular cell line, clotting factor or combination of clotting factors


• Therefore, solution is usually easy • For instance... • If the patient suffers from a lack of Factor

XXiXa (Dubrovnik) • Give the patient a couple of bags of Factor

XXiXa (Dubrovnik) before the block • Simples! • Advice - talk to a haematologist • If you can find one


Summary • There is little hard evidence to inform

practice

• The risk is low

• Some will avoid RA in patients with abnormal coagulation

• Modify risk by treating the coagulopathy or using different blocks if possible


Abnormality of nerves

• Should RA be used in patients with pre-existing neurological disorders?

Epidurals and MS No - it might affect

the abnormal nerves

It’s fine but pregnancy can make

MS worse and you don’t want to get the blame

There is no evidence whatsoever that it will affect

the MS - carry on!

Summary

• There are case reports of abnormal nerve function getting worse after RA

• But no hard evidence

• Familiar?

“Patients with pre-existing neurological disease may bat increased risk of new or worsening injury regardles of anaesthetic technique. When RA is thought to be appropriate for these patienmodifying the technique may minimise risk. Based on a moderate amount of animal data, such modifications may include using a less potent LA, min vasoconstrictors. Limited human data neither confirm nor refute these modifications”

Summary • There is little hard evidence to inform practice

• The risk is low

• Some will avoid RA in patients with neurological conditions

• Modify risk by using lower concentrations of LA if possible and avoiding adrenaline


Compartment syndrome

• A clash of two cultures

• Anaesthetists and orthopaedic surgeons

• Why do anaesthetists tend to take an instant dislike to orthopaedic surgeons they meet?

• Orthopods can rely on a substantial body of published material

CASE REPORT I had a patient who got compartment syndrome and didn’t do very well. They had an epidural so it must be th anaesthetist’s fault. Bashem-All F, et al Bone & Hammer 2011; 13: 12-15

CASE REPORT I had a patient who got compartment syndrome and didn’t do very well. They had a nerve block so it must be the anaesthetist’s fault. Thumpit R, et al Bone & Hammer 2012; 14: 22-25

CASE REPORT I had a patient who got compartment syndrome and didn’t do very well. They had an anaesthetic of some sort so it must be the anaesthetist’s fault. Blame-Game P, et al Bone & Hammer 2013; 15: 232-235

Literature survey • Publications referring to influence of

analgesic technique on diagnosis

• 28 case reports/case series

• Epidural: 23

• PCA: 3

• PNB: 2

Blame the analgesia

• Case series of 4 patients with tibial fractures

• PCA morphine blamed

• All had 0.5 - 1.0 mg morphine per hour

Analgesia to blame?

• Some cases where epidural provided postoperative “anaesthesia”

• PNBs not implicated

Conclusions • Pain is an unreliable symptom

• There are no RCTs or outcome-based comparative trials

• “There is no convincing evidence that PCA or RA delay the the diagnosis of compartment syndrome provided patients are adequately monitored”

What is the answer?

• Can you use RA in patients at risk from compartment syndrome?

• Sadly, there are entrenched views

It is never my fault that my operations go wrong!

My patients with tibial fractures must not have blocks!

What is the answer? • Do not adopt entrenched views

• Communicate with the surgeon

• PNBs or epidurals with dilute LAs can give good analgesia without obscuring signs of compartment syndrome (probably)

• Discuss with the patient as well as surgeon!

Summary • There is little hard evidence to inform practice

• The risk is low

• Some will avoid RA in patients at risk of compartment syndrome

• Modify risk by using lower concentrations of LA


Regional anaesthesia • Involves taking risks sometimes for the overall

benefit of patients

• And taking decisions on the basis of clinical judgement rather than hard data

• Because there are no hard data

• In a world in which protocols and guidelines are increasingly controlling us

• This amount of clinical freedom is fun

The End

La fin

Das ende

Fine

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Thank you

Merci

Danke

Grazie

mailto:[email protected]

when not to block

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