Influence of pulse oximetry and capnography on time to diagnosis of critical incidents in anesthesia: a pilot study using a full-scale patient simulator

Effects of multitasking on interpreting a spearcon sequence display for monitoring multiple patients

Spearcons are time-compressed speech phrases. When arranged in a sequence representing vital signs of multiple patients, spearcons may be more informative than conventional auditory alarms. However, multiple resource theory suggests that certain timeshared tasks might interfere with listeners' ability to understand spearcons. We tested the relative interference with spearcon identification from the following ongoing tasks: (1) manual tracking, (2) linguistic detection of spoken target words, (3) arithmetic true-false judgments, or (4) an ignored background speech control. Participants were 80 non-clinicians. The linguistic task worsened spearcon identification more than the tracking task, p < .001, and more than ignored background speech, p = .012. The arithmetic task worsened spearcon identification more than the tracking task, p < .001. The linguistic task and arithmetic task both worsened performance, p = .674. However, no ongoing task affected participants' ability to detect which patient(s) in a sequence had abnormal vital signs. Future research could investigate whether timeshared tasks affect non-speech auditory alerts.

Spearcon Sequences for Monitoring Multiple Patients: Laboratory Investigation Comparing Two Auditory Display Designs

OBJECTIVE

The aim was to compare the effectiveness of two auditory displays, implemented with spearcons (time-compressed speech), for monitoring multiple patients.

BACKGROUND

Sequences of sounds can convey information about patients' vital signs, such as oxygen saturation (SpO₂) and heart rate (HR). We tested whether participants could monitor five patients using spearcon-based sound sequences.

METHOD

A 2 × 3 within-subjects design was used. The first factor was interface, with two levels: the ALL interface used spearcons to convey vital signs for all five patients, whereas the ABN (abnormal) interface represented patients who had normal vital signs with a low-pitched single-tone sound and patients who had at least one abnormal vital sign with spearcons. The second factor was the number of patients who had at least one abnormal vital sign: there were one, two, or three such patients in each monitoring sequence. Participants were 40 nonclinicians.

RESULTS

Participants identified abnormal patients' SpO₂ and HR levels and located abnormal patients in the sound sequence more accurately with the ABN interface than the ALL interface. Accuracy declined as the number of abnormal patients increased. Participants associated ABN with easier identification of vital signs, resulting in higher ratings of confidence and pleasantness compared with ALL.

CONCLUSION

Sequences of spearcons may support effective eyes-free monitoring of multiple patients.

APPLICATION

Sequences of spearcons may be useful in monitoring multiple patients and the underlying design principles may extend to monitoring in other domains such as industrial process control or control of multiple autonomous vehicles.

A Novel Auditory Display for Neonatal Resuscitation: Laboratory Studies Simulating Pulse Oximetry in the First 10 Minutes After Birth

OBJECTIVE

We tested whether enhanced sonifications would improve participants' ability to judge the oxygen saturation levels (SpO₂) of simulated neonates in the first 10 min after birth.

BACKGROUND

During the resuscitation of a newborn infant, clinicians must keep the neonate's SpO₂ levels within the target range, however the boundaries for the target range change each minute during the first 10 min after birth. Resuscitation places significant demand on the clinician's visual attention, and the pulse oximeter's sonification could provide eyes-free monitoring. However, clinicians have difficulty judging SpO₂ levels using the current sonification.

METHOD

In two experiments, nonclinicians' ability to detect SpO₂ range and direction-while performing continuous arithmetic problems-was tested with enhanced versus conventional sonifications. In Experiment 1, tremolo signaled when SpO₂ had deviated below or above the target range. In Experiment 2, tremolo plus brightness signaled when SpO₂ was above target range, and tremolo alone when SpO₂ was below target range.

RESULTS

The tremolo sonification improved range identification accuracy over the conventional display (81% vs. 63%, p < .001). The tremolo plus brightness sonification further improved range identification accuracy over the conventional display (92% vs. 62%, p <.001). In both experiments, there was no difference across conditions in arithmetic task accuracy ( p >.05).

CONCLUSION

Using the enhanced sonifications, participants identified SpO₂ range more accurately despite a continuous distractor task.

APPLICATION

An enhanced pulse oximetry sonification could help clinicians multitask more effectively during neonatal resuscitations.

Novel Pulse Oximetry Sonifications for Neonatal Oxygen Saturation Monitoring: A Laboratory Study

OBJECTIVE

We aimed to test whether the use of novel pulse oximetry sounds (sonifications) better informs listeners when a neonate's oxygen saturation (SpO2) deviates from the recommended range.

BACKGROUND

Variable-pitch pulse oximeters do not accurately inform clinicians via sound alone when SpO2 is outside the target range of 90% to 95% for neonates on supplemental oxygen. Risk of blindness, organ damage, and death increase if SpO2 remains outside the target range. A more informative sonification may improve clinicians' ability to maintain the target range.

METHOD

In two desktop experiments, nonclinicians' ability to detect SpO2 range and direction of change was tested with novel versus conventional sonifications of simulated patient data. In Experiment 1, a "shoulder" sonification used larger pitch differences between adjacent saturation percentages for SpO2 values outside the target range. In Experiment 2, a "beacon" sonification used equal-appearing pitch differences, but when SpO2 was outside the target range, a fixed-pitch reference tone from the center of the target SpO2 range preceded every fourth pulse tone.

RESULTS

The beacon sonification improved range identification accuracy over the control display (85% vs. 60%; p < .001), but the shoulder sonification did not (55% vs. 52%).

CONCLUSION

The beacon provided a distinct auditory alert and reference that significantly improved nonclinical participants' ability to identify SpO2 range.

APPLICATION

Adding a beacon to the variable-pitch pulse oximeter sound may help clinicians identify when, and by how much, a neonate's SpO2 deviates from the target range, particularly during patient transport situations when auditory information becomes essential.

Anesthesia and the developing brain: relevance to the pediatric cardiac surgery

Anesthetic neurotoxicity has been a hot topic in anesthesia for the past decade. It is of special interest to pediatric anesthesiologists. A subgroup of children potentially at greater risk for anesthetic neurotoxicity, based on a prolonged anesthetic exposure early in development, are those children receiving anesthesia for surgical repair of congenital heart disease. These children have a known risk of neurologic deficit after cardiopulmonary bypass for surgical repair of congenital heart disease. Yet, the type of anesthesia used has not been considered as a potential etiology for their neurologic deficits. These children not only receive prolonged anesthetic exposure during surgical repair, but also receive repeated anesthetic exposures during a critical period of brain development. Their propensity to abnormal brain development, as a result of congenital heart disease, may modify their risk of anesthetic neurotoxicity. This review article provides an overview of anesthetic neurotoxicity from the perspective of a pediatric cardiac anesthesiologist and provides insight into basic science and clinical investigations as it relates to this unique group of children who have been studied over several decades for their risk of neurologic injury.

A two-year experience of an integrated simulation residency curriculum

BACKGROUND

Human Patient Simulation (HPS) is increasingly used in medical education, but its role in Emergency Medicine (EM) residency education is uncertain.

STUDY OBJECTIVES

The objective of this study was to evaluate the perceived effectiveness of HPS when fully integrated into an EM residency didactic curriculum.

METHODS

The study design was a cross-sectional survey performed in 2006, 2 years after the implementation of an integrated simulation curriculum. Fifty-four residents (postgraduate year [PGY] 1-4) of a 4-year EM residency were surveyed with demographic and curricular questions on the perceived value of simulation relative to other teaching formats. Survey items were rated on a bipolar linear numeric scale of 1 (strongly disagree) to 9 (strongly agree), with 5 being neutral. Data were analyzed using Student t-tests.

RESULTS

Forty residents responded to the survey (74% response rate). The perceived effectiveness of HPS was higher for junior residents than senior residents (8.0 vs. 6.2, respectively, p<0.001). There were no differences in perceived effectiveness of lectures (7.8 vs. 7.9, respectively, p=0.1), morbidity and mortality conference (8.5 vs. 8.7, respectively, p=0.3), and trauma conference (8.4 vs. 8.8, respectively, p=0.2) between junior and senior residents. Scores for perceptions of improvement in residency training (knowledge acquisition and clinical decision-making) after the integration of HPS into the curriculum were positive for all residents.

CONCLUSION

Residents' perceptions of HPS integration into an EM residency curriculum are positive for both improving knowledge acquisition and learning clinical decision-making. HPS was rated as more effective during junior years than senior years, while the perceived efficacy of more traditional educational modalities remained constant throughout residency training.

The effect of a graphical interpretation of a statistic trend indicator (Trigg's Tracking Variable) on the detection of simulated changes

Anaesthesia involves processing large amounts of information over time. One task of the anaesthetist is to detect substantive changes in physiological variables promptly and reliably. It has been previously demonstrated that a graphical trend display of historical data leads to more rapid detection of such changes. We examined the effect of a graphical indication of the magnitude of Trigg's Tracking Variable, a simple statistically based trend detection algorithm, on the accuracy and latency of the detection of changes in a micro-simulation. Ten anaesthetists each viewed 20 simulations with four variables displayed as the current value with a simple graphical trend display. Values for these variables were generated by a computer model, and updated every second; after a period of stability a change occurred to a new random value at least 10 units from baseline. In 50% of the simulations an indication of the rate of change was given by a five level graphical representation of the value of Trigg's Tracking Variable. Participants were asked to indicate when they thought a change was occurring. Changes were detected 10.9% faster with the trend indicator present (mean 13.1 [SD 3.1] cycles vs 14.6 [SD 3.4] cycles, 95% confidence interval 0.4 to 2.5 cycles, P = 0.013. There was no difference in accuracy of detection (median with trend detection 97% [interquartile range 95 to 100%], without trend detection 100% [98 to 100%]), P = 0.8. We conclude that simple statistical trend detection may speed detection of changes during routine anaesthesia, even when a graphical trend display is present.

Using information technology to improve quality in the OR

This article summarizes the current state of technology as it pertains to quality in the operating room, ties the current state back to its evolutionary pathway to understand how the current capabilities and their limitations came to pass, and elucidates how the overlay of information technology (IT) as a wrapper around current monitoring and device technology provides a significant advance in the ability of anesthesiologists to use technology to improve quality along many axes. The authors posit that IT will enable all the information about patients, perioperative systems, system capacity, and readiness to follow a development trajectory of increasing usefulness.

Advanced auditory displays and head-mounted displays: advantages and disadvantages for monitoring by the distracted anesthesiologist

BACKGROUND

In a full-scale anesthesia simulator study we examined the relative effectiveness of advanced auditory displays for respiratory and blood pressure monitoring and of head-mounted displays (HMDs) as supplements to standard intraoperative monitoring.

METHODS

Participants were 16 residents and attendings. While performing a reading-based distractor task, participants supervised the activities of a resident (an actor) who they were told was junior to them. If participants detected an event that could eventually harm the simulated patient, they told the resident, pressed a button on the computer screen, and/or informed a nearby experimenter. Participants completed four 22-min anesthesia scenarios. Displays were presented in a counterbalanced order that varied across participants and included: (1) Visual (visual monitor with variable-tone pulse oximetry), (2) HMD (Visual plus HMD), (3) Audio (Visual plus auditory displays for respiratory rate, tidal volume, end-tidal CO(2), and noninvasive arterial blood pressure), and (4) Both (Visual plus HMD plus Audio).

RESULTS

Participants detected significantly more events with Audio (mean = 90%, median = 100%, P < 0.02) and Both (mean = 92%, median = 100%, P < 0.05) but not with HMD (mean = 75%, median = 67%, ns) compared with the Visual condition (mean = 52%, median = 50%). For events detected, there was no difference in detection times across display conditions. Participants self-rated monitoring as easier in the HMD, Audio and Both conditions and their responding as faster in the HMD and Both conditions than in the Visual condition.

CONCLUSIONS

Advanced auditory displays help the distracted anesthesiologist maintain peripheral awareness of a simulated patient's status, whereas a HMD does not significantly improve performance. Further studies should test these findings in other intraoperative contexts.

The multimodal world of medical monitoring displays

A vision of the future of intraoperative monitoring for anesthesia is presented-a multimodal world based on advanced sensing capabilities. I explore progress towards this vision, outlining the general nature of the anesthetist's monitoring task and the dangers of attentional capture. Research in attention indicates different kinds of attentional control, such as endogenous and exogenous orienting, which are critical to how awareness of patient state is maintained, but which may work differently across different modalities. Four kinds of medical monitoring displays are surveyed: (1) integrated visual displays, (2) head-mounted displays, (3) advanced auditory displays and (4) auditory alarms. Achievements and challenges in each area are outlined. In future research, we should focus more clearly on identifying anesthetists' information needs and we should develop models of attention in different modalities and across different modalities that are more capable of guiding design.

Advanced patient monitoring displays: tools for continuous informing

We reviewed the use of advanced display technologies for monitoring in anesthesia. Researchers are investigating displays that integrate information and that, in some cases, also deliver the results continuously to the anesthesiologist. Integrated visual displays reveal higher-order properties of patient state and speed in responding to events, but their benefits under an intensely timeshared load is unknown. Head-mounted displays seem to shorten the time to respond to changes, but their impact on peripheral awareness and attention is unknown. Continuous auditory displays extending pulse oximetry seem to shorten response times and improve the ability to timeshare other tasks, but their integration into the already noisy operative environment still needs to be tested. We reviewed the advantages and disadvantages of the three approaches, drawing on findings from other fields, such as aviation, to suggest outcomes where there are still no results for the anesthesia context. Proving that advanced patient monitoring displays improve patient outcomes is difficult, and a more realistic goal is probably to prove that such displays lead to better situational awareness, earlier responding, and less workload, all of which keep anesthesia practice away from the outer boundaries of safe operation.

Patient simulation for training basic and advanced clinical skills

INTRODUCTION

Patient simulators are increasingly used in the education and training of healthcare professionals. This paper describes the history of human patient simulator development, the features of contemporary simulators, the acquisition of basic and advanced clinical skills using patient simulators, and the benefits, cost, limitations and effectiveness of this innovative learning modality.

SIMULATOR DEVELOPMENT

The development of human patient simulators began in the late 1960s, and accelerated in the late 1980s and early 1990s. Several simulator systems are now professionally manufactured, commercially available, and used at hundreds of medical centres, universities and colleges in the USA and throughout the world. Contemporary patient simulators have many clinical features, and look and respond to interventions with ever-increasing degrees of realism because sophisticated physiological and pharmacological models automatically control many features.

SIMULATOR USE IN MEDICAL EDUCATION

Simulators are used to teach basic skills, such as respiratory physiology and cardiovascular haemodynamics, and advanced clinical skills, e.g. management of difficult airways, tension pneumothorax, pulmonary embolism and shock.

BENEFITS, COSTS AND LIMITATIONS

The simulation laboratory offers distinct educational advantages, especially for learning how to recognise and to treat rare, complex, clinical problems. Costs of simulator-based educational programmes include facility, equipment and personnel. Current limitations include clinical realism of the patient manikin and faculty development.

Teaching sedation and analgesia with simulation

OBJECTIVE

This study reports on the efficacy of using the anesthesia simulator to teach sedation and analgesia to nurses. This provision of sedation and analgesia to a patient is accomplished with the goal of maintaining the ability of the patient to respond purposefully to auditory or tactile stimuli.

METHODS

Nurses working in areas of the hospital where conscious sedation is performed were the participants in this sedation and analgesia training course. Prior to the training session, the participants read the American Society of Anesthesiology Practice guidelines for sedation and analgesia by non-anesthesiologists. At the time of the training session, each participant completed a written pretest, had an introduction to sedation and analgesia with four clinical crisis teaching scenarios using the anesthesia simulator, a practical exam using the simulator, and a written post-test. Each participant was also given the opportunity to complete an evaluation of the session.

RESULTS

Twenty nurses completed the training session. The written tests had a maximum possible score of 30. Mean score on the written pretest was 22.9 +/- 3.54, and mean score on the written post-test was 26.0 +/- 4.24 (p < 0.001). Seventeen of the twenty subjects scored higher on the post-test. Mean practical exam score was 5.5 of a possible 6.0. Mean participant rating of the education session was 3.75 (1 = poor, 4 = excellent). All but one participant rated the length of the training session as "about right."

CONCLUSIONS

The anesthesia simulator provides an excellent tool for teaching conscious sedation skills to hospital nurses. The participants' test performance improved following the session, and they also rated the educational experience as excellent.

Performance evaluation of a new pulse oximeter during mild hypothermic cardiopulmonary bypass

Newly developed pulse oximeters (POs) are designed to display accurate SpO(2) during motion and hypoperfusion. We compared the performance of a new PO, the Masimo SET Radical (M), with a conventional PO, the Nihon Kohden AY-900P (N), during hypothermic cardiopulmonary bypass. Eighteen patients were studied prospectively. PO failure was defined as failure to show no SpO(2) value or show incorrect SpO(2) values for longer than 3 min continuously. PO failure occurred in 4 and 14 patients with M and N, respectively (P = 0.0022). All 4 patients in whom PO failure developed with M were among the 14 patients with N. No SpO(2) was provided for 4% +/- 12% of the duration of aorta cross-clamping with M and 36% +/- 39% with N (P = 0.002). Skin temperature and mean arterial blood pressure when PO failure started to occur and ended were similar between M and N. PO failure easily developed in patients with preoperative diuretic therapy or with intraoperative hyperlactatemia in N, but not in M. M was able to display accurate SpO(2) values significantly more frequently and longer than N during mild hypothermic cardiopulmonary bypass with nonpulsatile flow, suggesting that M is more useful for monitoring SpO(2) during hypoperfusion.

IMPLICATIONS

We compared the performance of a new pulse oximeter with that of a conventional pulse oximeter during hypothermic cardiopulmonary bypass with nonpulsatile flow. The newly developed device displayed accurate SpO(2) significantly more frequently and longer than a conventional oximeter. Newly developed pulse oximeters seem to be more useful for monitoring SpO(2) during hypoperfusion.

Assessment of clinical competence

Despite endless efforts in the quest for credible methods for evaluating clinical competence, the objective remains elusive. The components of competence include both clinical (interview skills, physical examination, differential diagnosis and therapeutic modalities) and technical skills. Written and oral examinations and, more recently, objective structured clinical examinations have been used as instruments for assessing the progress of trainees as well as for college or board certification and licensure to practice medicine. The American Board of Anesthesiology has adopted a more rigorous process for evaluating residents in training (Certificates of Clinical Competence). Newer methods have attempted to measure the competence of practicing physicians, including the analysis of data from physician-submitted 'report cards', 're-certification' examinations, and patient outcome studies. Whole-body computerized patient simulators have become a major area of research for teaching clinical skills and assessing behavior as well as patient management during critical incidents. This review examines the significant literature in each of the areas cited.