Thermal burns in electroconvulsive therapy

Abstract

Electroconvulsive therapy (ECT) is effective for mood disorders and schizophrenia. Thermal burns, while rare, are potentially sight and life threatening. The three elements necessary for a fire are often in close proximity during a session: an oxidiser (oxygen), an ignition source (faulty electrodes, poor contact with skin producing a spark) and fuel (hair, residual alcohol cleanser). This case report describes one such incident when a patient sustained a burn during ECT, with poor contact of electrode pad with skin, high impedance and an oxygen-rich environment possibly contributing. Given that ECT is conducted relatively frequently (once every 2–3 days) in a usual regimen, we make recommendations for safe application of electrode pads for temporal placement ECT.

Introduction

In Singapore, electroconvulsive therapy (ECT) is often performed to help patients with treatment-resistant depression and schizophrenia. ¹ It is generally prescribed as a fixed number of treatments, usually thrice weekly for 6 to 12 sessions. ²

An ECT device administers a pulsed electric current through the patient’s brain between two stimulus electrodes, usually placed above each temple on the patient’s head. The current produces a seizure in the patient; how this seizure improves the patient’s condition is still not yet fully understood.

The administration of ECT is a team effort by both the administering psychiatric doctor and an anaesthetist. First, the patient is pre-oxygenated either by face mask or positive pressure ventilation and then given a short acting muscle relaxant (most commonly succinylcholine) to minimise the severity of motor convulsions and reduce patient injury.

During ECT, the three elements necessary for a fire are often in close proximity: an oxidiser (oxygen), an ignition source (faulty electrodes, poor contact with skin producing a spark) and fuel (hair, residual flammable cleaning solvent). Careful patient preparation and coordination between the psychiatric doctor and anaesthetist is needed to prevent a fire: ensuring good skin-to-electrode contact with machine-run impedance tests before the treatment, avoiding the use of non-recommended skin preparation agents and removing oxygen sources just before the shock.

While electrode burns during ECT are rare (none reported in local journals in the last 10 years), the proximity to vital structures on the face means injuries are potentially life and sight threatening. One such incident reported in a 2007 Patient Safety Authority Report in the United States resulted in first- and second-degree burns on one ear and first-degree burns on the forehead above one eye. ³ Therefore, a burns incident during a session of ECT warrants a closer look at existing protocols to rule out potential lapses. We present a case of a thermal burn sustained during ECT.

Case report

The patient is a 37-year-old Chinese woman who had a 15-year history of systemic lupus erythematosus complicated by immune thrombocytopaenia, lupus nephritis and neuropsychiatric symptoms manifesting as mania, with auditory hallucinations and mood lability. She was also morbidly obese with a body mass index of 43, with concurrent obstructive sleep apnoea, and was not compliant to use of her continuous positive airway pressure device at night.

She was admitted a month prior to the procedure for a relapse of her neuropsychiatric symptoms presenting as mania and agitation. As she was prone to drowsiness and hypoxia if over-sedated, and her symptoms were not responsive to escalating doses of anti-psychotics; she was scheduled to undergo 12 sessions of ECT.

She was to undergo her third session of electroconvulsive therapy. As per her previous treatments, a standard protocol used in our department and similar to other local psychiatry departments was followed. Her skin was cleaned with a moist swab, and disposable bitemporal electrodes (Thymapad™, which comes fully coated with hydrogel) were applied. The impedance was recorded as high (>3000 ohm), so after further manipulation, the first set of Thymapads were discarded and replaced with a new set. The second set initially had high impedance, but after some manipulation achieved an impedance of about 2300 ohms, within the manufacturer’s recommended range (100–3000 ohm).

She was sedated with propofol and given succinylcholine to inhibit motor convulsions during the shock. While she was sedated, a bite block was inserted and high-flow oxygen therapy administered via a suitably sized face mask held over her nose and mouth with a good seal. The oxygen mask was then removed from the patient and a final impedance check was recorded as 2440 ohms before the stimulus was delivered.

Three seconds after the stimulus delivery, a small amount of smoke was noticed to be rising from the right temporal electrode. The electrode was immediately removed. The patient was ventilated by hand with high-flow oxygen via face mask until she regained spontaneous breathing and was able to maintain her airway.

The ECT report showed a final impedance of more than 3000 ohms, and no physical fit was seen. The electroencephalogram tracing was disrupted by movement and manipulation of the patient, and it was unlikely the patient had a generalised seizure.

Tetracycline ointment was applied to the affected electrode, and she was formally assessed by a plastic surgeon once back in the general ward. A 0.5% body surface area deep dermal burn was diagnosed and the wound treated with topical medication and regular dressings.

The patient underwent the rest of her ECT sessions with the right temporal electrode placed slightly above the burn site without further incident.

Discussion

We use the Thymatron® System IV device for ECT, and while other lead placements are available, bitemporal lead placement remains the most common. With resource limitations, the use of thymapads remains the most convenient and consistent way to deliver ECT, over the use of paddles in our setting.

An investigation into the incident, inspection of the equipment by the vendor and a review of the 2013 edition of the Thymatron® instruction manual (Figure 1) found some potential causes:

Both sets of Thymapads used were almost 2 years old and may have dried out, resulting in poor contact. They were not rehydrated.

The second set did have a lower impedance, but because they were old and there was some manipulation and re-application of the pads, the pad may have lost its adhesiveness and come loose easily. Without good contact with the patient’s skin, heat built up, causing the burn.

The proximity of the electrode to the patient’s hairline was another factor as it could have led to hair being trapped between the electrode and skin and being set alight.

Figure 1.

Standard skin preparation procedure for electrode placement, per Thymatron® instruction manual (2013 edition).

The vendor informed that although the Thymapads were still safe for use up to 2 years after manufacture, any pads older than 1 year should be considered old and rehydrated with running water and pre-tac solution used.

In the event of an electrode burn or fire, we recommend

immediate removal of the electrode,

extinguish any flames with saline and

secure airway if there is suspicion of airway burns.

In cases of high impedance, or difficulty with the Thymapads application, we recommend:

Repeat skin preparation:

• Use a saline-moistened gauze pad to wipe and then dry the skin (do not use alcohol or solvents).

• If available, spread 1-2 droplets of pre-tac solution onto skin site and lightly rub until dry.

• Adjust position of pads to avoid hair (or shave the hair if appropriate).

• Remove the pads (especially if more than 1 year since manufacture) and pass them under running water, then shake off excess water ensuring no water left on surface of pad and wait a few minutes and re-apply the Thymapad by pressing firmly in place.

• Check wires and connections are secure.

If impedance is still high

• put conduction gel on the Thymapads and be careful to wipe excess gel around the pad and

• apply direct pressure onto the pad throughout delivery of stimulus.

Pressure should be applied during stimulus delivery if impedance is high, or if pads are poorly adhesive. Pressure can be applied either with

• insulated gloved hands or

• foam handle end of the hand electrodes.

If impedance is still high, consider switching to handheld paddles instead of Thymapads.

Although instructions are that impedance below 2700 ohms is acceptable, we aim to achieve lower than that for good contact.

Conclusion

Thermal burns in electroconvulsive therapy are rare but life and sight threatening. A burns incident during a session of ECT warrants a closer look at existing protocols to rule out potential lapses. Precautions during the procedure and ensuring low impedance are essential.