Blood pressure expert supports hospital mercury ban
By Paul Jones
Developments toward safer working environments for hospital workers exposed to mercury received a boost late last year. International medical opposition to phasing out mercury manometers for measuring blood pressure was reversed when a leading hypertension expert endorsed environmental emission targets drafted at the Third International Conference on the Protection of the North Sea.
Marking the centenary of the invention of human blood pressure measurement (sphygmomanometry), the December 7, 1996, issue of Britain's prestige medical journal Lancet carried a two-page article by Professor Eoin O'Brien of the blood pressure unit at Beaumont Hospital, Dublin, which contains significant admissions.
The article sounds the death knell for the sphygmomanometer, a polluting instrument accounting for many tonnes of highly toxic mercury being in our environment, and an unknown degree of occupational disease in hospital workers.
The basic format of the mercury manometer hasn't changed since the Renaissance, and was adapted for medicine by Italian physician Riva-Roci, who added the rubber arm cuff, in 1896.
Mercury spills from the gauge when it is accidentally overinflated. It is then spread around the hospital via vacuum cleaners, and lodges in cracks and carpet. It is virtually impossible to rid a contaminated building of mercury.
O'Brien's earlier 1995 editorial in Journal of Human Hypertension described claims published in the New Scientist, that illegal levels of mercury vapour could come from sphygmoes, as "emotive journalism". But O'Brien's 1996 Lancet view states, "... mercury will probably be banned from hospital use because of the danger of toxicity ...".
Mythical claims of superior accuracy have been mainstay pro-mercury machine arguments. But O'Brien now states: "To begin with, we should accept that blood pressure measurement as done in clinical practice today is a very inaccurate procedure, yet one on which we are prepared to base management decisions with serious far reaching consequences for the patient".
The accuracy myth was also recently debunked in a leaked letter to potential customers from the operations manager for Tyco Instruments, Ed Wright, whose company makes both mercury and aneroid gauges. The letter reads, "... we continually promote our aneroid unit as the preferred modality over a mercury gravity manometer ... mercury units are often out of calibration."
Queensland's Health Department tested and approved non-mercury, lifetime certified, Tyco aneroid gauges for a state stores supply, but Royal Brisbane Hospital (RBH) has not removed obsolete mercury gauges. In June a survey at Ward 7F South, RBH, showed 30% of 30 wall-mounted mercury manometers in the ward had been levered off wall mounts by hydraulic beds.
The beds were introduced by senior nurses without risk assessment. According to nurses, other units were dangerously loose. Some of the units broke, spilling mercury. No action preventing further damage has been taken.
The Queensland Nurses Union remains silent. In three years since this issue began at RBH, the QNU has omitted any reference to the nature of the hazard in its journal.
Hazard warning labels for mercury manometers, an RBH staff member initiative, state: "Caution. Liquid mercury. Handle with care."
RBH modified labels from those recommended by Division of Workplace Health and Safety, omitting the risk phrases "Toxic by inhalation. Cumulative effects."
Understandably, many Queensland University of Technology nurses in training believe they have to drink mercury to be affected.