• All women undergoing procedures with local anaesthetic drugs are at risk of toxicity.

• If there are signs of mild local anaesthetic toxicity, the obstetric anaesthetist should be contacted and asked to review the patient. The patient should not be left alone until reviewed.

• Severe local anaesthetic toxicity is a life-threatening emergency which can cause sudden deterioration in neurological and cardiovascular status, or cardiac arrest.

• All staff should be aware of the location of the local anaesthetic toxicity boxes in their area of work.

• In the event of cardiac arrest from local anaesthetic toxicity the usual ALS treatment algorithm should be followed in the addition to giving Intralipid 20%.

• IF OPENING THIS DOCUMENT IN AN EMERGENCY, GO TO SECTIONS 3-4 FOR THE MANAGEMENT GUIDELINE OF SEVERE LA TOXICITY IN OBSTETRIC PATIENTS

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Abbreviations

Local anaesthetic drugs are used frequently in obstetric patients and to great benefit. Toxicity from this group of medications is rare but potentially life-threatening and requires prompt recognition and treatment.

2.1 Local anaesthetic drugs: drugs used to achieve local anaesthesia by chemical blockade of peripheral nerves.

2.2 Women at risk of toxicity: all women with epidurals, undergoing spinal anaesthesia, and women having local infiltration to allow for repair of episiotomy are at risk of toxicity.

2.3 Local anaesthetic toxicity: the signs, symptoms and physiological changes associated with dangerously high doses of local anaesthetic drugs (further divided into mild and severe).

2.3 Mild toxicity: signs and symptoms suggestive of toxicity which are not immediately life threatening, but which may progress into severe toxicity.

2.4 Severe toxicity: signs and symptoms suggestive of immediately life-threatening toxicity.

2.5 Intralipid 20%: this is a preparation of intravenous emulsion that may be used in cases of local anaesthetic toxicity which have cause cardiac arrest or severe cardiovascular collapse (i.e., refractory to initial supportive treatments). Its use for local anaesthetic toxicity is unlicensed but is recommended by the Association of Anaesthetists in Great Britain and Ireland.

2.6 Maximum Safe Doses: the doses for local anaesthetic drugs are given as maximum safe dose (i.e., doses which should not be exceeded). Maximum safe doses are weight based and should be calculated from the woman’s booking weight. Bupivacaine and lidocaine are the most commonly used local anaesthetic drugs in the obstetric unit at this trust. Maximum safe doses are as follows:

Recognition

• Sudden alteration in mental status: severe agitation, loss of consciousness (with or without tonic-clonic convulsions)
• Cardiovascular collapse: hypotension, sinus bradycardia, conduction blocks, asystole and ventricular tachyarrhythmias may all occur
• Local anaesthetic (LA) toxicity may occur some time after an initial injection |

Immediate Management

• Stop injecting the LA (detach PCEA pump if present)
• Call for help
• Maintain the airway, check breathing and check pulse
• Give oxygen: 15L via reservoir mask or 100% via Water’s circuit
• Call ‘2222’: ‘Anaesthetic Emergency’ + ‘Obstetric Emergency’ ‘Cardiac Arrest’ if cardiac arrest diagnosed
• Ensure IV access
• Monitoring: SpO2 + NIBP + ECG
• Consider VBG or ABG but do not delay definitive treatment
• If seizures give anti-convulsants (benzodiazepine, thiopental or propofol)

Treatment

If Cardiac Arrest

• Start CPR using ALS protocols
• Manage arrhythmias using ALS protocols
• Arrhythmias may be very refractory to treatment
• Consider peri-mortem LSCS if pregnant
• Consider referral for ECMO

GIVE Intralipid 20%

• Follow regime below
• Continue CPR throughout treatment with lipid emulsion
• Recovery from LA-induced cardiac arrest may take >1 h

If Not Cardiac Arrest

Use conventional therapies to treat:

• Hypotension
• Bradycardia
• Tachyarrhythmias

CONSIDER Intralipid 20%

Propofol is not a suitable substitute for lipid emulsion Lidocaine should not be used as an anti-arrhythmic therapy

Follow-up

• Arrange safe transfer to a clinical area with appropriate equipment and suitable staff until sustained recovery is achieved
• Exclude pancreatitis by regular clinical review, including daily amylase or lipase assays for two days
• Report cases to the National Patient Safety Agency (via www.npsa.org.uk)
• If lipid has been given, please also report its use to the international registry at www.lipidrescue.org

In pregnancy use Ideal Body Weight (IBW) for Intralipid 20% dose (IBW (kg) = height (cm) – 110)

Intralipid 20% Locations

FPH: Crash Trollies in CDS, Main Theatres, PACU, DSU1 & DSU2

WXP: LW – epidural trolley, Main theatres pharmacy cupboard

An approximate dose regimen for a 70-kg patient would be as follows:

An approximate dosing regime for a 60kg (IBW) woman would be as follows:

4.1 Women at Risk of Toxicity

4.1.1 Epidural for Labour: these women receive low concentrations of local anaesthetic (0.1% bupivacaine with 2micrograms/ml fentanyl) through the trust patient controlled epidural anaesthetic pump (PCEA) with a pre-programmed lock-out time which reduces the risk of exceeding maximum safe doses. However, those women having top-up doses of 0.25% bupivacaine for resistant labour pain, or top ups with higher concentrations of bupivacaine for trial of instrumental in the delivery room will be at increased risk.

4.1.2 Epidural for Surgery: these women receive higher concentrations of local anaesthetic drugs so the risk of toxicity is higher. In addition, recent top-up doses just prior to emergency surgery may bring doses closer to the maximum safe doses. Anaesthetists should be vigilant and check the dose with the safe maximum dose for the patient’s booking weight. Mixing local anaesthetic drugs (e.g., 50mg bupivacaine with 200mg lidocaine) is common practice but means that careful calculations of maximum doses must be made.

4.1.3 Spinal Anaesthesia: given the low doses of local anaesthetic required for spinal anaesthesia (e.g., 12.5mg bupivacaine) the risk of toxicity should be low, but vigilance must still be maintained.

4.1.4 Episiotomy Repair: the doses required for this procedure should be less than the maximum safe doses but the area is highly vascular meaning absorption into the circulation may be quicker than expected.

4.2 Identification and Management of Mild Toxicity

The features of mild toxicity are

• Tingling or numbness of the tongue or around the mouth

• Metallic taste

• Mild visual disturbance (e.g., difficulty focusing)

• Light-headedness

If mild toxicity is suspected, then any injection or infusion of local anaesthetic drug must be stopped immediately. The obstetric anaesthetist should be contacted immediately and review the patient promptly. Mild toxicity may rapidly progress to severe toxicity and so the patient must not be left alone in case of further deterioration.

If symptoms resolve and the patient remains stable for the next 15-30 minutes, then the likelihood severe toxicity is low. Further analgesic and anaesthetic management is at the discretion of the anaesthetist. An explanation should be offered to the patient regarding the above and a rationale for any change in analgesic or anaesthetic management.

4.3 Other Causes of Collapse in Pregnancy

A number of other conditions in pregnant women may cause sudden changes in mental status, seizures, cardiovascular collapse or cardiac arrest. Toxicity should be suspected in anyone who is being administered local anaesthetic drugs, especially if there is a history of symptoms of mild toxicity immediately before deterioration. However, other causes should be considered (summarised below):

• Neurological

  • Eclampsia

  • Intracranial haemorrhage

  • Venous sinus thrombosis

• Cardiovascular

  • Pulmonary embolus / amniotic fluid embolus

  • Myocardial infarction

  • Peri-partum cardiomyopathy

  • Concealed haemorrhage (e.g., placental abruption)

• Other

  • Anaphylaxis

  • Septic shock

4.4 Intralipid Dosing in Pregnancy:

Intralipid comes as a 20% emulsion (200mg/ml). The dose is based on ideal body weight. In an emergency this information may not be immediately available and so estimation of ideal body weight is acceptable, noting that the ideal body weight of a woman 1.60m tall is 50kg and ideal body weight for a woman who is 1.80m tall is 70kg.

Ideal Body Weight in kg (women) = height (cm) – 110

4.5 Location of Intralipid

both sites must ensure that in-date Intralipid 20% is available as part of the Intralipid Kit Box and is kept in the designated areas:

Frimley Park Crash trollies in labour ward and main theatres PACU

Wexham Park In labour ward on the epidural trolley and in the labour ward storeroom (ask the midwife in charge) and in the Pharmacy cupboard in main theatres.

The Intralipid will be checked on the first day of every month and after it is used. It is the responsibility of the member of staff checking the crash trolley to ensure that at total of 1250mls of Intralipid 20% is stocked in the trolley and is in date. A copy of the management guidelines should also be with the crash trolley. If Intralipid is used, then the intralipid form which has been sent to pharmacy should be replaced. At Wexham Park the intralipid is checked by the in-charge ODP and the midwives stocking the epidural trolley.

5.1 Epidurals for Labour: the ultimate responsibility for any epidural is with the obstetric anaesthetist. However, the midwife will be in the room during epidural top-ups via the PCEA and should be familiar with the signs and symptoms of toxicity, the immediate management, and call the anaesthetist if toxicity is suspected.

5.2 Perineal Repair: these procedures are often done in the delivery room without anaesthetic involvement. The responsibility for the dose of local anaesthetic used is with the obstetrician. If signs or symptoms of toxicity (mild or severe) develop during the procedure the obstetric anaesthetist should be contacted immediately.