An unusual case of hypercarbia during general anesthesia

[Pollution and retro-pollution by the distribution system of medical gases]

The anaesthetic machine, the recovery room or the ICU ventilator as well as any other simple oxygenation device can be accidentally supplied with a "wrong" gas, or a mixture of "wrong" and "true" gases, or a gas containing chemical impurities, as a result of one of the following causes: a) the source of the medical gas pipeline supply contains a "wrong" gas or impurities; b) the gas pipeline is polluted by a "wrong" gas or solvents, introduced during the installation or maintenance of the pipeline; c) the pipeline is polluted by a wrong gas at a point of inter-connection or cross-connection of two pipelines; d) supply of a "wrong" gas through wrong quick couplers connected to the pipeline; e) back flow of a gas in another pipeline supply through a defective gas mixer, which is today the most common cause of pipeline contamination or retropollution. It occurs with some types of mixers in case of absence or malfunction of non-return valves, associated with a pressure difference between the two gas lines. The means of prevention, recognition and emergency treatment of these events include: a) systematic removal of mixers and flowmeter-mixers from supplies when not in use; b) periodical checking of these devices for an accidental communication between the gases to be mixed; c) systematic use of an oxygen analyser for a continuous measurement of FIO2, especially when the machine is connected to the N2O pipeline supply; d) the presence of a reserve cylinder of oxygen connected to every anaesthetic machine.

An analysis of the factors leading to crossed gas lines causing profound hypercarbia during general anesthesia

With increasing use of laparoscopic techniques to facilitate surgical procedures in closed cavities, our institution has installed piped-in carbon dioxide (CO2) in most of our operating rooms. This case report describes an occurrence of a nitrous oxide hose being connected to a CO2 outlet, resulting in profound hypercarbia. The factors, human and mechanical, leading to this error are discussed, as well as the process of diagnosis and the subsequent treatment.