13 de agosto de 2010

Artigo recomendado: Use of Medical Simulation to Explore Equipment Failures and Human-Machine Interactions in Anesthesia Machine Pipeline Supply Crossover

1.   Seshadri C. Mudumbai, MD*†, 
2.   Ruth Fanning, MBBCh, MRCPI, FFARCSI†, 
3.   Steven K. Howard, MD*†, 
4.   M. Frances Davies, PhD† and 
5.   David M. Gaba, MD*† 

+ Author Affiliations
1.    From the *Veterans Administration Palo Alto Health Care System, Palo Alto; and 
2.    †Stanford University School of Medicine, Stanford, California. 

Anesthesia & Analgesia May 2010 vol. 110 no. 5 1292-1296

Background: High-fidelity medical simulation can be used to explore failure modes of technology and equipment and human-machine interactions. We present the use of an equipment malfunction simulation scenario, oxygen (O2)/nitrous oxide (N2O) pipeline crossover, to probe residents’ knowledge and their use of anesthetic equipment in a rapidly escalating crisis.

Methods: In this descriptive study, 20 third-year anesthesia residents were paired into 10 two-member teams. The scenario involved an Ohmeda Modulus SE 7500 anesthetic machine with a Datex AS/3 monitor that provided vital signs and gas monitoring. Before the scenario started, we switched pipeline connections so that N2O entered through the O2 pipeline and vice versa. Because of the switched pipeline, the auxiliary O2 flowmeter delivered N2O instead of O2. Two expert, independent raters reviewed videotaped scenarios and recorded the alarms explicitly noted by participants and methods of ventilation.

Results: Nine pairs became aware of the low fraction of inspired O2 (FIO2) alarm. Only 3 pairs recognized the high fraction of inspired N2O (FIN2O) alarm. One group failed to recognize both the low FIO2 and the high FIN2O alarms. Nine groups took 3 or more steps before instigating a definitive route of oxygenation. Seven groups used the auxiliary O2 flowmeter at some point during the management steps.

Conclusions: The fact that so many participants used the auxiliary O2 flowmeter may expose machine factors and related human-machine interactions during an equipment crisis. Use of the auxiliary O2 flowmeter as a presumed external source of O2 contributed to delays in definitive treatment. Many participants also failed to notice the presence of high N2O. This may have been, in part, attributable to 2 facts that we uncovered during our video review: (a) the transitory nature of the “high N2O” alert, and (b) the dominance of the low FIO2 alarm, which many chose to mute. 
We suggest that the use of high-fidelity simulations may be a promising avenue to further examine hypotheses related to failure modes of equipment and possible management response strategies of clinicians.

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