Contamination of piped medical gas supply with water

Abstract

The failure of anaesthetic equipment as a result of maintenance is extremely rare. The ingress of water into the flowmeters of an anaesthetic machine from the piped medical air supply is reported and is possibly unique. The piped medical air supply was open to the atmosphere during maintenance. Water condensed in the gas pipeline and this was not noticed during subsequent testing. Water was seen leaking from the orthopaedic air tools used for surgery but was assumed to be from the autoclaving process. Later the same day, when medical air from the piped source was used as part of the gas mixture for a general anaesthetic, water was seen filling the barrel of the flowmeter air control valve. This could have had far-reaching and dangerous consequences for the patient, which were fortunately averted.

Critical incident is a possibility with water in flowmeter

“…[ 7 ] It can eventually spill over to other flowmeters with possibility of hypoxic mixture being delivered to the patient. [ 8 9 ] This requires constant vigilance to prevent any catastrophe. It is important to note that routine preoperative apparatus checklist may not prevent such critical incidents as water can enter at any point of time during use.…”

Water contamination of the central air supply: Out of sight, out of mind!

“…[ 1 ] The probable causes of water contaminating the MGPS include manual water drain operated at longer time interval or drain clogging, absence of desiccant air dryer, exposure of central air pipeline to atmosphere and absence of alarms for water level. [ 2 3 4 5 ]…”

Water in a nitrous oxide flowmeter

“…A similar incident had been reported earlier, where a central air pipeline was found contaminated by water condensation, as it was kept open to atmosphere during maintenance. [ 1 ]We feel that purging of hoses must be done with central pipeline dry gases before connecting the yoke adapter to the machine for prevention of this problem. In addition to patient safety concerns, any water in the gas supply would also lead to malfunction of vaporisers and a major break down in the modern anaesthesia machines with electronic components.…”