Development and Evaluation of Just-in-Time Training to Provide Cardio-Pulmonary Resusciation

More than 350,000 people die annually of cardiac arrest. In response to this epidemic, automated defibrillators are advocated, but they do not provide important respiratory support. However, adding respiratory support makes the system more complex and difficult to use. To solve this problem we developed a graphical computer based “just-in-time” training that instructs a responder to follow a standard treatment protocol. We simulated a medical emergency in a patient simulator and asked novice volunteers to care for the patient. When using a paper-based version of the treatment protocol (based on a NASA protocol), subjects took significant longer to remove an obstruction from the airway and stabilize the injured person than when using an animated graphic treatment protocol. These findings validate the potential of graphically based just-in-time training to instruct novices in tasks they have not performed before.

Evaluation of the effect of information integration in displays for ICU nurses on situation awareness and task completion time: A prospective randomized controlled study

OBJECTIVE

The study measured whether nurses' situation awareness would increase and task completion time decrease when they used an integrated information display compared to traditional displays for medication management, patient awareness and team communication.

SETTING

The Burn Trauma Intensive Care Unit (BTICU) at the University Hospital, University of Utah Health Science Center, Salt Lake City, Utah, USA.

PARTICIPANTS

12 experienced BTICU nurses.

MEASURES

Situation awareness (accuracy of the participants' answer) and task completion time (response time from seeing the question to submitting the answer) were measured using paper prototypes of both displays.

STUDY DESIGN

Counter-balanced (on display order), repeated-measures design.

MAIN RESULTS

Nurses had a higher situation awareness when using the integrated display, with an overall accuracy of 85.3% compared to 61.8% with the traditional displays (odds ratio 3.61, P<.001, 95% CI=2.34…5.57). Task completion times were nearly half with integrated displays compared to traditional displays (median 26.0 and 42.1s, hazard ratio 2.31, P<.001, CI=1.83…2.93).

CONCLUSIONS

An integrated ICU information display increased nurses' situation awareness and decreased task completion time. Information integration has the potential to decrease errors, increase nurses' productivity and may allow nurses to react faster to a patient's clinical needs. Bidirectional device communication is needed for these displays to achieve full potential in improving patient safety.

Intensive care unit nurses' information needs and recommendations for integrated displays to improve nurses' situation awareness

OBJECTIVE

Fatal errors can occur in intensive care units (ICUs). Researchers claim that information integration at the bedside may improve nurses' situation awareness (SA) of patients and decrease errors. However, it is unclear which information should be integrated and in what form. Our research uses the theory of SA to analyze the type of tasks, and their associated information gaps. We aimed to provide recommendations for integrated, consolidated information displays to improve nurses' SA.

MATERIALS AND METHODS

Systematic observations methods were used to follow 19 ICU nurses for 38 hours in 3 clinical practice settings. Storyboard methods and concept mapping helped to categorize the observed tasks, the associated information needs, and the information gaps of the most frequent tasks by SA level. Consensus and discussion of the research team was used to propose recommendations to improve information displays at the bedside based on information deficits.

RESULTS

Nurses performed 46 different tasks at a rate of 23.4 tasks per hour. The information needed to perform the most common tasks was often inaccessible, difficult to see at a distance or located on multiple monitoring devices. Current devices at the ICU bedside do not adequately support a nurse's information-gathering activities. Medication management was the most frequent category of tasks.

DISCUSSION

Information gaps were present at all levels of SA and across most of the tasks. Using a theoretical model to understand information gaps can aid in designing functional requirements.

CONCLUSION

Integrated information that enhances nurses' Situation Awareness may decrease errors and improve patient safety in the future.

ICU nurses' evaluations of integrated information displays on user satisfaction and perceived mental workload

Consolidated information from multiple sources (patient monitors, electronic medical records, infusion pumps, ventilators, medication references) may improve nurses' work and patient safety. Objective. Two hypotheses were tested, that integrated information displays (a) improve nurses' satisfaction and (b) lower perceived mental workload. Methods. In a counter-balanced, repeated measures design (integrated vs. traditional display) 12 ICU nurses performed realistic tasks using both display types. Results. Nurses' user interaction satisfaction was higher with the integrated display and it received more positive comments. Nurses' mean perceived mental workload scores were also lower, having significant differences in effort and frustration dimensions. A lower mental workload may reduce errors and improve treatment times. Integrated information displays have great promise, but technological factors such as bidirectional device communication must be addressed if these displays are to achieve their potential for improving patient safety.

The evaluation of a pulmonary display to detect adverse respiratory events using high resolution human simulator

OBJECTIVE

Authors developed a picture-graphics display for pulmonary function to present typical respiratory data used in perioperative and intensive care environments. The display utilizes color, shape and emergent alerting to highlight abnormal pulmonary physiology. The display serves as an adjunct to traditional operating room displays and monitors.

DESIGN

To evaluate the prototype, nineteen clinician volunteers each managed four adverse respiratory events and one normal event using a high-resolution patient simulator which included the new displays (intervention subjects) and traditional displays (control subjects). Between-group comparisons included (i) time to diagnosis and treatment for each adverse respiratory event; (ii) the number of unnecessary treatments during the normal scenario; and (iii) self-reported workload estimates while managing study events.

MEASUREMENTS

Two expert anesthesiologists reviewed video-taped transcriptions of the volunteers to determine time to treat and time to diagnosis. Time values were then compared between groups using a Mann-Whitney-U Test. Estimated workload for both groups was assessed using the NASA-TLX and compared between groups using an ANOVA. P-values < 0.05 were considered significant.

RESULTS

Clinician volunteers detected and treated obstructed endotracheal tubes and intrinsic PEEP problems faster with graphical rather than conventional displays (p < 0.05). During the normal scenario simulation, 3 clinicians using the graphical display, and 5 clinicians using the conventional display gave unnecessary treatments. Clinician-volunteers reported significantly lower subjective workloads using the graphical display for the obstructed endotracheal tube scenario (p < 0.001) and the intrinsic PEEP scenario (p < 0.03).

CONCLUSION

Authors conclude that the graphical pulmonary display may serve as a useful adjunct to traditional displays in identifying adverse respiratory events.

Evaluation of a pulmonary graphical display in the medical intensive care unit: An observational study

We developed a pulmonary graphic display that depicts pulmonary physiological variables for intubated, mechanically ventilated patients in a graphical format. The pulmonary graphical display presents multiple respiratory variables and changes are depicted by alterations in shape and color. Learning how this new technology will be integrated and accepted by users is an important step before it is introduced into the clinical arena. This study observed use and acceptance of the pulmonary graphical display by health care providers in an intensive care unit. Investigators noted that physicians, respiratory therapists, and nurses observed the pulmonary graphical display on average six, three, and one times, respectively, per patient room entry. Based on questionnaires, the pulmonary graphical display was perceived as useful, a desirable addition to current ICU monitors, and an accurate representation of respiratory variables.

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.

The employment of an iterative design process to develop a pulmonary graphical display

OBJECTIVE

Data representations on today's medical monitors need to be improved to advance clinical awareness and prevent data vigilance errors. Simply building graphical displays does not ensure an improvement in clinical performance because displays have to be consistent with the user's clinical processes and mental models. In this report, the development of an original pulmonary graphical display for anesthesia is used as an example to show an iterative design process with built-in usability testing.

DESIGN

The process reported here is rapid, inexpensive, and requires a minimal number of subjects per development cycle. Three paper-based tests evaluated the anatomic, variable mapping, and graphical diagnostic meaning of the pulmonary display.

MEASUREMENTS

A confusion matrix compared the designer's intended answer with the subject's chosen answer. Considering deviations off the diagonal of the confusion matrix as design weaknesses, the pulmonary display was modified and retested. The iterative cycle continued until the anatomic and variable mapping cumulative test scores for a chosen design scored above 90% and the graphical diagnostic meaning test scored above 75%.

RESULTS

The iterative development test resulted in five design iterations. The final graphical pulmonary display improved the overall intuitiveness by 18%. The display was tested in three categories: anatomic features, variable mapping, and diagnostic accuracy. The anatomic intuitiveness increased by 25%, variable mapping intuitiveness increased by 34%, and diagnostic accuracy decreased slightly by 4%.

CONCLUSION

With this rapid iterative development process, an intuitive graphical display can be developed inexpensively prior to formal testing in an experimental setting.

Clinical evaluation of the Life Support for Trauma and Transport (LSTAT) platform

INTRODUCTION

The Life Support for Trauma and Transport (LSTAT trade mark ) is a self-contained, stretcher-based miniature intensive care unit designed by the United States Army to provide care for critically injured patients during transport and in remote settings where resources are limited. The LSTAT contains conventional medical equipment that has been integrated into one platform and reduced in size to fit within the dimensional envelope of a North Atlantic Treaty Organization (NATO) stretcher. This study evaluated the clinical utility of the LSTAT in simulated and real clinical environments. Our hypothesis was that the LSTAT would be equivalent to conventional equipment in detecting and treating life-threatening problems.

METHODS

Thirty-one anesthesiologists and recovery room nurses compared the LSTAT with conventional monitors while managing four simulated critical events. The time required to reach a diagnosis and treatment was recorded for each simulation. Subsequently, 10 consenting adult patients were placed on the LSTAT after surgery for postoperative care in the recovery room. Questionnaires about aspects of LSTAT functionality were completed by nine nurses who cared for the patients placed on the LSTAT.

RESULTS

In all of the simulations, there was no clinically significant difference in the time to diagnosis or treatment between the LSTAT and conventional equipment. All clinicians reported that they were able to manage the simulated patients properly with the LSTAT. Nursing staff reported that the LSTAT provided adequate equipment to care for the patients monitored during recovery from surgery and were able to detect critical changes in vital signs in a timely manner.

DISCUSSION

Preliminary evaluation of the LSTAT in simulated and postoperative environments demonstrated that the LSTAT provided appropriate equipment to detect and manage critical events in patient care. Further work in assessing LSTAT functionality in a higher-acuity environment is warranted.

Semicontinuous cardiac output monitoring using a neural network

OBJECTIVES

This study compared 2-mL bolus thermodilution cardiac output measurements with standard 10-mL bolus measurements.

DESIGN

Cardiac output was measured with the new 2-mL bolus technique and the 10-mL standard thermodilution technique in a perspective series. We describe a system that automatically cools and injects 2-mL boluses of saline into a standard pulmonary artery catheter. It uses a Peltier effect solid-state cooler and pneumatically driven syringe injector to measure cardiac output once per minute.

SETTING

Animal laboratory.

ANIMALS

Eight adult Duroc swine weighing between 38.0 and 57.5 kg.

INTERVENTIONS

Once each minute, 2 mL of cooled 5% dextrose was injected through the pulmonary catheter. Once every 8 mins, four sequential measurements of cardiac output were made using 10-mL injections.

MEASUREMENTS AND MAIN RESULTS

A total of 1249 paired waveforms were processed with both a conventional algorithm and with a neural network. For the conventional algorithm, the correlation coefficient was r2 = .92 and the SD of the difference was 1.30 L/min. For the neural network, the correlation coefficient was r2 = .94 and the SD of the difference was 0.88 L/min. Output filtering improved the results in both cases.

CONCLUSION

Neural networks accurately derive cardiac output from 2-mL bolus thermodilution injections, allowing cardiac output to be monitored automatically once per minute in many patients. The technique is convenient and uses standard low-cost catheters.

A closed rebreathing system for dose maintenance during Partial Liquid Ventilation

Partial Liquid Ventilation (PLV), a treatment for acute respiratory failure in which the lungs are filled, either partially or to functional residual capacity (FRC), with perfluorochemical (PFC) liquid while the patient is on mechanical gas ventilation, has progressed to clinical trials using the PFC perflubron (PFB). Because gas expired during PLV is laden with PFB vapor, PFB is lost via evaporation, which increases dose consumption and necessitates periodic redosing. A device has been developed to minimize evaporative loss by confining PFC vapor to a gas volume breathed by the patient, which is isolated from the ventilator. This closed rebreathing system works with the ventilator such that after the lung is filled with PFB, the patient is connected to the rebreathing system, with breathing still "driven" by the ventilator. The rebreathing system consists of two gas circuits, or compartments, separated by a flexible bag (in a box) partition. One compartment is in gas communication with the lung, while the second communicates with the ventilator. The O2 level on the patient side is matched to that on the ventilator side by sensing gas concentrations and by feedback control of O2 introduction. Similarly, air is introduced into the patient side under pressure-based feedback control to maintain a constant gas volume. On inspiration, the ventilator delivers the tidal volume (breath) into the box surrounding the bag, which, in turn, is transmitted through the bag to the lung. On expiration, the process is reversed. Unidirectional circulation of gas in the rebreathing circuit is achieved via check valves, and expired CO2 is removed by a barium hydroxide lime cartridge. Airway humidification is maintained by captive water vapor in the system and water vapor from the CO2 absorber. It is recommended that flow, pressure, O2, and CO2 levels be monitored at the patient "Y," i.e., the proximal end of the endotracheal tube. Performance data from both in-vitro experiments and in-vivo PLV experiments in pigs are presented. The authors conclude that with the closed rebreathing system, the dose can be safely maintained with fewer redosing procedures, and an approximately 90% savings in dose is achieved.

Clinical evaluation of tracheal pressure estimation from the endotracheal tube cuff pressure

OBJECTIVE

Air flow through an endotracheal tube causes a pressure drop across the tube. This pressure drop creates a difference between air pressure measured in the trachea and the pressure measured in the breathing circuit, which can lead to errors when calculating pulmonary mechanics and when setting ventilators. We have developed a method of estimating tracheal pressure from the pressure in the endotracheal tube cuff and tested this system in clinical trials.

METHODS

Pressure measurement ports were placed between the Y piece of the ventilator circuit and the ETT connector, in the trachea at the carinal end of the ETT, and in the ETT cuff inflation line. Tracheal pressures and cuff pressures were found at end-inspiration and end-expiration (no flow states) and used to define a linear relationship between cuff pressure and tracheal pressure. Using the estimated tracheal pressure (Ptrach) and the measured pressure at the Y piece of the breathing circuit (PY), the pressure drop across the ETT was found as a function of flow through the tube. Tracheal pressure was then calculated from the flow-dependent pressure drop and PY. Tests of this system were performed in six patients in the operating room and six patients in the intensive care unit.

RESULTS

The flow-based tracheal pressure estimates were within 0.7 +/- 0.4 cm H2O of actual tracheal pressure (mean +/- SD). At peak inspiratory pressure the difference averaged 0.5 +/- 0.3 cm H2O. The difference between our estimate of tracheal pressure and actual tracheal pressure was always less than 1 cm H2O.

CONCLUSION

The flow-based tracheal pressure estimates were accurate during intermittent spontaneous breathing, but not during spontaneous breathing or with a poorly inflated cuff. The estimates were more immune to noise than the cuff-based estimates of tracheal pressure. The estimates of tracheal pressure measured from the ETT cuff should be accurate enough for clinical use in the operating room.

Evaluation in animals of a system to estimate tracheal pressure from the endotracheal tube cuff

OBJECTIVE

Flow through an endotracheal tube (ETT) causes a pressure loss across the tube. This loss results in a difference between pressure measured at the airway and pressure measured in the trachea. This difference can lead to errors when calculating pulmonary mechanics and when setting ventilators. We have tested a method of estimating tracheal pressure from the pressure in the ETT cuff.

METHODS

Pressure transducers were placed in the proximal ETT connector, in the trachea, and in the ETT cuff (through the inflation port). Instantaneous periods of zero flow, detected with a flow meter, were used to calculate the slope and offset of the line relating cuff pressure to tracheal pressure. The system was tested on the bench using a ventilator and lung simulator and in 2 dogs and 5 pigs. Tests were performed at various cuff pressures, trachea diameters, ETT sizes, respiratory rates, tidal volumes, and airway obstructions.

RESULTS

In bench tests, our estimate of tracheal pressure was within -4.0 +/- 2.6% of the actual tracheal pressure (mean +/- standard deviation [SD]). In animal tests, our estimation of tracheal pressure was within -0.6 +/- 5%. In all bench test measurements and in 40 of 42 animal measurements, the error was less than 1 cm H2O.

CONCLUSIONS

The cuff estimation technique gives real-time, continuous, noninvasive tracheal pressure measurements in intubated animals with cuffed ETTs.

Noninvasive blood pressure monitoring from the supraorbital artery using an artificial neural network oscillometric algorithm

OBJECTIVE

Our objective was to overcome the limitations of linear models of oscillometric blood pressure determination by using a nonlinear technique to model the relationship between the oscillometric envelope and systolic and diastolic blood pressures, and then to use that technique for near-continuous arterial pressure monitoring at the supraorbital artery.

METHODS

An adhesive pressure pad and transducer were used to collect oscillometric data from the supraorbital artery of 85 subjects. These data were then used to train an artificial neural network (ANN) to report diastolic or systolic pressure. Arterial pressure measurements defined by brachial artery auscultation were used as a reference. ANN results were compared with those obtained using a standard oscillometric algorithm that determined pressures based on fixed percentages of the maximum oscillometric amplitude.

RESULTS

The ANN produced better estimates of reference blood pressures than the standard oscillometric algorithm. Mean difference between target and actual output for the ANN was 0.50 +/- 5.73 mm Hg for systolic pressures, compared to the mean difference of the standard algorithm of 2.78 +/- 19.38 mm Hg. For diastolic pressures, the ANN had a mean difference of 0.04 +/- 4.70 mm Hg, while the mean difference of the standard algorithm was -0.34 +/- 9.75 mm Hg.

CONCLUSIONS

The ANN produced a better model of the relationship between the oscillometric envelope and reference systolic and diastolic pressures than did the standard oscillometric algorithm. Noninvasive blood pressure measured from the supraorbital artery agreed with pressure measured by auscultation in the brachial artery, and may sometimes be more clinically useful than an arm cuff device.

Refractive indices for volatile anesthetic gases: equipment and method for calibrating vaporizers and monitors

OBJECTIVE

The objective of our study was to establish the refractive indices and the virial coefficients of the volatile anesthetic vapors. These indices and coefficients will allow refractometry to be used by manufacturers to produce accurate calibration, without requiring expensive high-precision calibration gases.

METHODS

We used a precision refractometer to measure the refractive indices for five volatile anesthetic vapors. We prepared our calibration gases by mixing a gravimetrically calibrated amount of liquid agent with a constant gas flow.

RESULTS

The refractive indices for the volatile anesthetic vapors are 1,603.2 for halothane, 1,540.4 for enflurane, 1,563.3 for isoflurane, 1,538.3 for sevoflurane, and 1,211.7 for desflurane. The maximum theoretical error in our measurements, due to all sensors and all uncertainty in our measurement of apparatus and physical constants, is +/- 0.56% of the reading (+/- 0.70% for desflurane).

CONCLUSIONS

If refractometry replaced calibration gases in cylinders, as a calibration standard, manufacturers might avoid errors that now occur because calibration gases manufactured by numerous companies seem to differ. We propose that our values serve as an interim database.

A laboratory investigation of two new portable gas analysers

Two new portable infrared gas analysers, the Irina (Drägerwerke, Lübeck, Germany) and the Normac (Datex Instrumentarium Corporation, Helsinki, Finland), were tested and the results compared to those from such established methods as gaschromatography and the Beckman LB-2 (Beckman, USA) infrared gas analyser using exactly defined gas mixtures from a vaporizer developed in our laboratory. The analysers were evaluated for their accuracy and precision, noise, zero stability, gain stability and the impact of flow, over-pressure, carrier gas and humidity. All three analysers showed good accuracy and precision. The noise level was acceptable except in the older version of the Normac, but this error has now been corrected by the manufacturer. Zero and gain stability are very good; gas flow and over-pressure do not affect the measurement. The influence of carrier gases and humidity is negligible except for the strong N2O effect on the Beckman. We conclude that this new generation of highly sophisticated and reliable but handy analysers will meet the clinical demands.

Determination of the partial pressure of halothane (or isoflurane) in blood

A gas chromatographic method is described for the direct quantitative determination of the partial pressure of halothane (or isoflurane) in blood as well as the blood-gas partition coefficient. A head space technique and a flame ionization detector were used. Standard blood was obtained by equilibrating patients' blood with known gas concentrations in a tonometer. Using an infra-red analyser to measure the halothane gas concentration in the tonometer and within the anaesthetic system allowed for the direct comparison of the partial pressure in blood to the partial pressure in the inspired gas. Technical problems associated with this procedure, and with comparable methods, are discussed.

Use of indirect calorimetry in the nutritional management of burned patients

The use of indirect calorimetry in assessing and monitoring nutritional support in burn patients is reported. Twenty-nine patients with a mean burn size of 35% TBSA were monitored with 228 measurements of resting energy expenditure (REE), calculations of respiratory quotient (RQ), and substrate metabolism. Daily weights, nitrogen balance determinations, and routine laboratory tests were also obtained. Oxygen consumption (VO2) was 186 +/- 39 ml/min/M2, corresponding to REE of 2,506 +/- 543 kcal/day. REE varied during the course of wound healing, demonstrating a biphasic course. Metabolic rate was also significantly increased with the performance of routine procedures such as dressings and surgery. Measurements of REE were a mean 76% of predictions based on the Curreri formula, and 1.47 times basal energy expenditure (BEE) calculated by the Harris-Benedict equation. Neither formula provided for the great variations observed in daily, and individual, measurements of REE. During the study, patients consumed 2,900 +/- 811 kcal/day, which exceeded REE by 1.14. This was associated with mean weight loss of 3.2% (range, -16 to 9%). RQ was less than 0.85 in 9% of determinations, but exceeded 1.0 24% of the time. Protein accounted for 17 +/- 3% of total metabolism, corresponding to a calorie:nitrogen ratio of 128:1. Practically, however, provision of this much protein proved difficult. Routine use of indirect calorimetry permits tailoring of nutritional support for burn patients, and is valuable in the early detection of significant under- or overnutrition.