• You are anaesthetising a fit and well 40 year old

woman for total abdominal hysterectomy for

menorrhagia. You induce with fentanyl, propofol

and atracurium. Following intubation you note she

appears flushed and the lungs are difficult to inflate.

The pulse is very faint and you cannot record a

blood pressure.

• What would be your immediate reaction?

• What are the possible diagnoses?

• Once stabilised what other therapies would you consider?

• Would you carry on with the surgery?

• What initial investigations would you carry out?

• What is the difference between anaphylactic and anaphylactoidreactions?

• Name 2 common presenting features of anaphylaxis

• What is the most important drug in the treatment of anaphylactic shock?

• What are the most common group of drugs to cause anaphylaxis in anaesthesia?

• Name 3 vasoactive substances released into the plasma in anaphylaxis

• How would you investigate to find the causative agent?

Objectives1. Define

2. Pathophysiology (a bit)

3. An anaesthesia perspective

4. Clinical manifestations

5. Commonly implicated agents

6. Management

• Anaphylaxis-o Ana- greek for “against”, “exceedingly”.

o Phylaxis- greek for “guarding”, “protection”

• It is an acute, potentially fatal, multisystemic

syndrome resulting from sudden ,florid mast cell and

basophil degranulation and subsequent release of

pro-inflammatory mediators into circulation.

Mechanisms• Immunologic-

• IgE mediated

• Immune complex mediated (complement pathway)

• Non-immunologic-• Direct mast cell degranulation (e.g. Cremophor, Vancomycin,

Opiates, ACE inh.)

• Irrespective of the initial insult the effects

“downstream” are identical.

Mast cell degranulation

inflammatory mediators and hence symptoms

Recruitment of additional inflammatory cells

More inflammatory mediators

Viscious cycle(positive feed-back)

• Mediatorso Histamine

o Tryptase

o Serotonin

o Prostaglandins and leukotrienes

o Interleukins

o PAF

o NO

An anaesthesia perspective

• Incidence 1:10,000 to 1:20,000

• The recognition of anaphylactic reactions in

anaesthesia is compromised by• Inability of patient to communicate early symptoms

• Obscured view of patient (Drapes)

• Anaphylactic respiratory and cardiovascular symptoms similar to

those produced by anaesthetic agents.

• Due to the myriad of drug used in any given intra-

operatively, identification of the inciting agent is

difficult.

Clinical manifestations• It has been noted that anaphylactic reactions are

multi-organ, though specifically for humans,

respiratory and cardiovascular symptoms represent

the most salient and potentially fatal manifestations.

• Cardiovascularo Myocardial depression

o Bradycardia

o Fluid shift(hypotension) –shift of fluid from intra to extravascular space

• Resulting in shock(distributive) and may progress to

cardiac arrest.

• Respiratoryo Upper airway

• Laryngeal edema/obstruction;oropharyngeal edema.

o Lower airway

• Bronchospasm; Pulmonary hyperinflation; oedema; hemorrhage

• Ultimately resulting in respiratory failure/arrest.

• Cutaneouso Urticaria; Erythema

Commonly implicated agents

• More commono Neuromuscular blocking agents

o Latex

o antibiotics

• Neuromuscular blocking agentso Implicated in 50-70% of cases ??

o Histamine release common with Mivacurium,

o Tubocurarine; Atracurium; Rapacuronium; Pancuronium; Succinylcholine;

Vecuronium.

• Antibioticso Vancomycin

o Penicillins

o Cephalosporins

• Latex (especially natural)o Gloves

o Drains

o Catheters

• Less commono Opiods

o Colloids and plasma expanders

o Barbiturates and propofol with cremophor

o Blood transfusion

o Nsaids

o Iodine

o Local anaesthetics

o Heparin

o Protamine

Management • Adopted from AAGBI guideline

• Immediate management

• Team-working is key

o ABC

o Remove all potential causative agents and maintain anaesthesia, if

necessary, with an inhalational agent.

o CALL FOR HELP and note the time.

• Maintain the airway and administer oxygen 100%.

Intubate the trachea if necessary and ventilate the

lungs with oxygen.

• Elevate the patient’s legs if there is hypotension.

*ACLS if in cardiac arrest

• Give adrenaline i.v.

◦ Adult dose: 50 µg (0.5 ml of 1:10 000 solution).

◦ Child dose: 1.0 µg.kg-1 (0.1 ml.kg-1 1:100 000

solution).

*If multiple doses are required within a short interval of

time start infusion.

• Give saline 0.9% or lactated Ringer’s solution at a

high rate via an intravenous cannula of an

appropriate gauge (large volumes may be

required).◦ Adult: 500 - 1 000 ml

◦ Child: 20 ml/kg

• Plan transfer of the patient to an appropriate

Critical Care area.

• Secondary management

Give chlorphenamine i.v.o Adult: 10 mg

o Child 6 - 12 years: 5 mg

o Child 6 months - 6 years: 2.5 mg

o Child <6 months: 250 µg.kg-1

Give hydrocortisone i.v.o Adult: 200 mg

o Child 6 - 12 years: 100 mg

o Child 6 months - 6 years: 50 mg

o Child <6 months: 25 mg

• If the blood pressure does not recover despite an

adrenaline infusion, consider the administration of

an alternative i.v. vasopressor according to the

training and experience of the anaesthetist, e.g.

metaraminol.

• Treat persistent bronchospasm with an i.v. infusion of

salbutamol. If a suitable breathing system

connector is available, a metered-dose inhaler may

be appropriate. Consider giving i.v. aminophylline

or magnesium sulphate.