The lives of thousands of patients may be at risk because UK hospitals are failing to replace old and undependable anaesthetic machines.

Researchers in Newcastle came to this conclusion when their survey found that nearly 30 per cent of hospitals use anaesthetic machines that cannot protect patients against potentially lethal doses of nitrous oxide in operating theatres.

The survey involved 51 NHS hospitals and found that, of the 1357 anaesthetic machines in these hospitals, 370 had no antihypoxia devices to prevent the delivery of nitrous oxide without oxygen. Many of these machines were located in emergency rooms, operating theatres and, in some cases, maternity units.

The researchers estimate that if the figures in their survey apply nationwide, it then translates into more than 3000 machines without an antihypoxia device that may currently be in use in hospitals across the UK.

The Royal College of Anaesthetists has introduced guidelines to force hospitals to replace the older machines with newer models with protective devices by December 2002. The Medical Devices Agency also acknowledges the need to replace older machines but, at the moment, there is little monitoring of hospitals to check whether they are acting upon this advice (BMJ, 2001; 323: 629).