Volts, amps and seconds: how ECT has changed

Electroconvulsive therapy (ECT) was first used in the 1930s. Since that time there have been great advances in medical technology (and in understanding of the brain) but ECT has not changed much. People are given an electric shock just as they were over 70 years ago. Is the shock – or stimulus as psychiatrists prefer to call it – any different today than it was in the early days?

Here are a few examples of electrical parameters from articles about ECT the 1940s:

  • 18 joules of energy – 0.35 seconds
  • 20-150 volts – 0.1 to 0.5 seconds
  • Voltages up to 150 – time up to one-third of a second (in patients with an exceptionally high seizure threshold)
  • Current of 250-800 milliamps – 0.1 to 0.2 seconds
  • 70-135 volts, current of 400-1200 milliamps – 0.25 to 0.5 seconds

The current in these early examples was always sine-wave (which is still in use in some countries).

An example of a modern electrical parameters are found in an advertisement for the Thymatron machine (a brief-pulse machine):

  • Current of 900 milliamps, up to 450 volts – up to 8 seconds. Maximum output (across 220 ohms) of 99.4 joules (198.8 joules with double-dose)

While over the years the voltage and current have remained relatively constant there has been a massive increase in the duration of the electric shock. In the olden days patients were given a shock lasting a fraction of a second. Nowadays the current flows, typically, for several seconds. The Ectron series 5 machine, for example, delivered a shock lasting 3.25 seconds, while on the more recent series 5A the controls could be adjusted from 1 second to 6 seconds.

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