Competing anesthesiology demands cause missed signals

By Eleanor McDermid, Senior medwireNews Reporter

Competing visual demands and high background noise increase the risk for anesthesiologists missing pulse oximeter pitch changes, shows research.

A simulated test, involving 33 resident anesthesiologists, showed that the effects of visual attention demands and background noise were additive. The two factors combined significantly reduced the likelihood for the anesthesiologists detecting a pulse oximeter pitch change from 99% to 98% oxygen saturation.

"These deficits were seen not only in the ability to accurately detect a change in oxygen saturation, but also in the speed of reaction when a change was detected," say lead researcher Ryan Stevenson (Vanderbilt University Medical Center, Nashville, Tennessee, USA) and colleagues.

"An additional point of emphasis here is that even the most difficult condition in this laboratory setting undoubtedly greatly underestimates the complexity and challenges of a real-world operating room," they write in Anesthesiology.

They note that the visual task employed in the study required a constant level of attention and so did not realistically mimic the requirements of all stages of anesthesia care. The background noise level used was an average of 67 dB sound pressure level, which is significantly quieter than the average 77 dB sound pressure level that has been reported for operating rooms.

With no background noise and a low visual attention load, the anesthesiologists detected the change in pulse oximeter pitch about 95% of times. This fell to about 92% at a high visual attention load and to less than 80% with the addition of prerecorded operating room background noise.

The average response time rose from less than 500 ms with a low visual attention load and no background noise to about 650 ms with a high load and noisy conditions.

"Given that the majority of anesthesia-related accidents are derivative of compounding small errors, such as not detecting a change in oxygen saturation, improving such monitoring performance may lead to reduced accident rates," say Stevenson et al.

They therefore say call for focus on reducing distracting environmental factors in operating rooms.

"Specifically, efforts to reduce distracters and decrease background noise should be considered during induction and emergence, periods of intense concentration for anesthesiologists and during which they are required to further divide their attention and are thus susceptible to higher rates of error."

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