Effects of divided attention and operating room noise on perception of pulse oximeter pitch changes: a laboratory study

Abstract

Background: Anesthesiology requires performing visually oriented procedures while monitoring auditory information about a patient's vital signs. A concern in operating room environments is the amount of competing information and the effects that divided attention has on patient monitoring, such as detecting auditory changes in arterial oxygen saturation via pulse oximetry.

Methods: The authors measured the impact of visual attentional load and auditory background noise on the ability of anesthesia residents to monitor the pulse oximeter auditory display in a laboratory setting. Accuracies and response times were recorded reflecting anesthesiologists' abilities to detect changes in oxygen saturation across three levels of visual attention in quiet and with noise.

Results: Results show that visual attentional load substantially affects the ability to detect changes in oxygen saturation concentrations conveyed by auditory cues signaling 99 and 98% saturation. These effects are compounded by auditory noise, up to a 17% decline in performance. These deficits are seen in the ability to accurately detect a change in oxygen saturation and in speed of response.

Conclusions: Most anesthesia accidents are initiated by small errors that cascade into serious events. Lack of monitor vigilance and inattention are two of the more commonly cited factors. Reducing such errors is thus a priority for improving patient safety. Specifically, efforts to reduce distractors and decrease background noise should be considered during induction and emergence, periods of especially high risk, when anesthesiologists has to attend to many tasks and are thus susceptible to error.

Figures

Figure 1. Methods

Panel A shows the experimental setup, with visual tasks presented directly in front of the anesthesiologist while the auditory pulse oximetry stimuli are presented at 90° to the right. Panel B shows frequencies measured were fit with an exponential function to derive the frequencies associated with each level of arterial oxygen saturation. Panels C and D show the visual tasks for the medium and high attentional load conditions, respectively. The visual task for the low attentional task was simple fixation and therefore is not depicted.

Figure 2. Accuracies and response times with the pulse oximeter

(A) Pulse Oximetry Accuracy; (B) Pulse Oximetry Response Time: Resident anesthesiologists were less likely to detect changes in oxygen saturation as attentional load increased and in noise. These effects were additive. Anesthesiologists were also slower to respond to changes in oxygen saturation under high attentional loads and noisy conditions. Bars represent mean responses and error bars represent standard errors.

Figure 3. Accuracies and response times with attentional tasks

(A) Visual Task Accuracy; (B) Visual Task Response Time: Visual tasks aimed at modulating attentional load through task difficulty were successful, as seen by the decrease in accuracy and slower response times with high attentional conditions. Bars represent mean responses and error bars represent standard errors.