The effect of ketamine and fentanyl on haemodynamics during intubation in pre-hospital and retrieval medicine.

BACKGROUND: Ketamine use for rapid sequence intubation (RSI) is frequent in pre-hospital and retrieval medicine (PHARM) and is associated with potentially deleterious haemodynamic changes, which may be ameliorated by concurrent use of fentanyl. OBJECTIVES: To describe the frequency with which fentanyl is used in conjunction with ketamine in a system where its use is discretionary, and to explore any observed changes in haemodynamics with its use. METHODS: A retrospective observational study of over 800 patients undergoing RSI with ketamine ± fentanyl in the PHARM setting between 2015 and 2019. The primary outcome was the proportion of patients in each group who had a systolic blood pressure (SBP) outside a pre-specified target range, with adjustment for baseline abnormality, within 10 min of anaesthetic induction. RESULTS: Eight hundred and seventy-six patients were anaesthetised with ketamine, of whom 804 were included in the analysis. 669 (83%, 95% CI 80%-86%) received ketamine alone, and 135 (17%, 95% CI 14%-20%) received both fentanyl and ketamine. Median fentanyl dose was 1.1 mcg/kg (IQR 0.75-1.5 mcg/kg). Systolic blood pressure (SBP) at induction was consistently associated with SBP after intubation in multivariable logistic regression, but fentanyl use was not associated with a change in odds of meeting the primary outcome (OR 1.08; 95% CI 0.72-1.60), becoming hypertensive (OR 1.35; 95% CI 0.88-2.07) or hypotensive (OR 0.76; 95% CI 0.47-1.21). CONCLUSIONS: The addition of fentanyl to ketamine for RSI was not associated with an alteration of the odds of post-induction haemodynamic stability, although the doses used were low. These findings justify further study into the optimal dosing of fentanyl during RSI in pre-hospital and retrieval medicine.

Does the addition of fentanyl to ketamine improve haemodynamics, intubating conditions or mortality in emergency department intubation: A systematic review.

BACKGROUND: Ketamine is an induction agent frequently used for general anaesthesia in emergency medicine. Generally regarded as haemodynamically stable, it can cause hypertension and tachycardia and may cause or worsen shock. The effects of ketamine may be improved by the addition of fentanyl to the induction regime. We conducted a systematic review to identify evidence with regard to the effect of adding fentanyl to an induction regime of ketamine and a paralysing agent on post-induction haemodynamics, intubating conditions and mortality. METHODS: We conducted a search of the Cochrane library, EMBASE, MEDLINE, PROQUEST, OpenGrey and clinical trial registries. Prominent authors were contacted in order to identify additional literature pertinent to the research question. Studies were included if they pertained to intubation of adult patients in the prehospital or emergency department environments and included an induction regime of ketamine and a paralysing agent, with at least one outcome measure of haemodynamics, intubating conditions or mortality. Search results were reviewed by two investigators independently, adjudicated by a third investigator where disagreement occurred. RESULTS: One observational study was identified that partially answered the research question. DISCUSSION: Only one observational study was identified that partially answered the research question. This paper demonstrated that the use of fentanyl as a pretreatment increases the incidence of post-induction hypotension, a phenomenon that was seen with propofol, midazolam and ketamine. The difference in hypotension between these agents was not statistically significant. The impact of this on patient-orientated outcomes is unclear.

Anterior Cruciate Ligament Injury, Reconstruction, and the Optimization of Outcome.

Anterior cruciate ligament reconstruction (ACLR) provides an established surgical intervention to control pathological tibiofemoral translational and rotational movement. ACLR is a safe and reproducible intervention, but there remains an underlying rate of failure to return to preinjury sporting activity levels. Postoperative pathological laxity and graft reinjury remain concerns. Previously, unrecognized meniscal lesions, disruption of the lateral capsule, and extracapsular structures offer potential avenues to treat and to therefore improve kinematic outcome and functional results, following reconstruction. Addressing laterally based injuries may also improve the durability of intraarticular ACLR. Improving the anterior cruciate ligament (ACL) graft replication of the normal ACL attachment points on the femur and the tibia, using either double bundle or anatomical single bundle techniques, improves kinematics, which may benefit outcome and functionality, following reconstruction.

Trust and the Compliance-Reliance Paradigm: The Effects of Risk, Error Bias, and Reliability on Trust and Dependence.

OBJECTIVE: This study provides a theoretical link between trust and the compliance-reliance paradigm. We propose that for trust mediation to occur, the operator must be presented with a salient choice, and there must be an element of risk for dependence. BACKGROUND: Research suggests that false alarms and misses affect dependence via two independent processes, hypothesized as trust in signals and trust in nonsignals. These two trust types manifest in categorically different behaviors: compliance and reliance. METHOD: Eighty-eight participants completed a primary flight task and a secondary signaling system task. Participants evaluated their trust according to the informational bases of trust: performance, process, and purpose. Participants were in a high- or low-risk group. Signaling systems varied by reliability (90%, 60%) within subjects and error bias (false alarm prone, miss prone) between subjects. RESULTS: False-alarm rate affected compliance but not reliance. Miss rate affected reliance but not compliance. Mediation analyses indicated that trust mediated the relationship between false-alarm rate and compliance. Bayesian mediation analyses favored evidence indicating trust did not mediate miss rate and reliance. Conditional indirect effects indicated that factors of trust mediated the relationship between false-alarm rate and compliance (i.e., purpose) and reliance (i.e., process) but only in the high-risk group. CONCLUSION: The compliance-reliance paradigm is not the reflection of two types of trust. APPLICATION: This research could be used to update training and design recommendations that are based upon the assumption that trust causes operator responses regardless of error bias.

The Role of Trust as a Mediator Between System Characteristics and Response Behaviors.

OBJECTIVE: The purpose of the current work was to clarify how subjective trust determines response behavior when interacting with a signaling system. BACKGROUND: In multiple theoretical frameworks, trust is acknowledged as a prime mediator between system error characteristics and automation dependence. Some researchers have operationally defined trust as the behavior exhibited. Other researchers have suggested that although trust may guide operator responses, trust does not completely determine the behavior. METHOD: Forty-four participants interacted with a primary flight simulation task and a secondary signaling system task. The signaling system varied in reliability (90%, 60%) and error bias (false alarm, miss prone). Trust was measured halfway through the experimental session to address the criterion of temporal precedence in determining the effect of trust on behavior. RESULTS: Analyses indicated that trust partially mediated the relationship between reliability and agreement rate. Trust did not mediate the relationship between reliability and reaction time. Trust also did not mediate the relationships between error bias and reaction time or agreement rate. Analyses of variance generally supported specific behavioral and trust hypotheses, indicating that the paradigm employed produced similar effects on response behaviors and subjective estimates of trust observed in other studies. CONCLUSION: These results indicate that strong assumptions of trust acting as the prime mediator between system error characteristics and response behaviors should be viewed with caution. APPLICATION: Practitioners should consider assessing factors other than trust to determine potential operator response behaviors, which may be more predictive.

An investigation of training strategies to improve alarm reactions.

Researchers have suggested that operator training may improve operator reactions; however, researchers have not documented this for alarm reactions. The goal of this research was to train participants to react to alarms using sensor activity patterns. In Experiment 1, 80 undergraduates monitored a simulated security screen while completing a primary word search task. They received spatial, temporal, single sensor, or no training to respond to alarms of differing reliability levels. Analyses revealed more appropriate and quicker reactions when participants were trained and when the alarms were reliable. In Experiment 2, 56 participants practiced time estimation by simple repetition, performance feedback, or performance feedback and temporal subdivision. They then reacted to alarms based on elapsed time between sensor activity and alarm onset. Surprisingly, results indicated that participants did not benefit differentially from temporal interval training, focusing instead on advertised system reliability. Researchers should replicate these findings with realistic tasks and real-world complex task operators.

The effects of external motivation and real-time automated feedback on speeding behavior in a naturalistic setting.

OBJECTIVE: In this field experiment, the authors tested an alerting system and a monetary incentive system with the objective of reducing speeding more than 5 mph faster than the posted speed limit. BACKGROUND: Speeding is a factor in a significant number of traffic fatalities. The systems tested in this project have been evaluated outside but not within the United States. These studies indicated that similar systems led to reductions in speeding. METHOD: For this study, eight vehicles were instrumented such that vehicle speed and speed limits were linked in real time. A total of 50 participants drove assigned vehicles for 4 weeks. Week 1 was a baseline period; during Week 2 or Week 3, 40 participants experienced the alerting system that issued auditory and visual advisory signals when drivers exceeded the limit by 5 mph or more. Of these 40 individuals, 20 experienced the monetary incentive system during Weeks 2 and 3; Week 4 was a return-to-baseline period. A control group of 10 drivers experienced neither system during the study. RESULTS: Results indicated that the incentive system resulted in significant reductions in driving faster than the posted limit, and the feedback system led to modest changes in speeding. In the condition in which drivers experienced the feedback and incentive, reductions in speeding were similar to those found during the incentive-only condition. CONCLUSION: The technology tested in this study has potential to benefit traffic safety by reducing the incidence of driving faster than the posted limit, which should lead to a reduction in speed-related crashes. APPLICATION: Insurers provide incentive-based discounts on premiums. Combining this technology with such a discount program may improve traffic safety significantly.

Training time estimation to improve alarm reactions.

Prior researchers have demonstrated that training may be an effective strategy for improving operator reactions to alarm systems with less than perfect reliability. Of the training strategies tested, recognition of temporal patterns in prior sensor activations seems to offer the greatest promise for improving the speed and appropriateness of subsequent alarm reactions. The current research was completed to clarify which of three temporal interval training methods leads to the most appropriate alarm reactions. Fifty-six undergraduates evaluated whether alarms occurring after sensor activations were true or false, based on elapsed time between the sensor signals and the alarm signals. Participants completed five training sessions to learn to estimate time intervals using simple repetition training, performance feedback, or performance feedback plus subdivision cues. Contrary to expectations, results indicated that participants did not benefit differentially from temporal interval training. Differences between pre- and posttest interval estimation performance was similar among groups, and training groups performed comparably when reacting to signals. Participants generally focused on advertised alarm system reliability, responding more appropriately and more quickly to lower reliability alarms. Future researchers and designers should replicate these findings with realistic tasks and real-world complex task operators to determine their generalization.

Hydroxyapatite-coated femoral stem/porous-coated acetabulum survivorship at 15 years.

At 10 years, we reported survivorship of the Omnifit hydroxyapatite-coated femoral stem and the Omnifit-PSL porous-coated dual-radius acetabular shell (Stryker, Mahwah, NJ) with polyethylene liners sterilized by gamma radiation in air. Our 15-year follow-up examines survivorship and functional outcomes of this system. Ninety-two patients (98 hips) were identified from our database who had been involved with the prior study. The mean follow-up was 14.7 years (range, 11.8-17.0 years). Survival of the stem and cup was 98.8% and 69%, respectively. Osteolysis was seen in 56% of the proximal femur and 5% of the distal femur. This hydroxyapatite-coated stem continues to perform well at 15 years despite poor acetabular results. The performance of this acetabular component is consistent with previous literature.

Posterior sternoclavicular disruption with ipsilateral clavicle fracture in a nine-year-old hockey player.

Posterior sternoclavicular joint disruptions are rare, and a concomitant fracture is even less common in the pediatric population. This case report concerns a posterior sternoclavicular joint disruption and ipsilateral medial clavicle fracture in a 9-year-old male hockey player. We describe the various imaging modalities that may be necessary for this injury, the complications to be considered in dealing with this injury as well as an internal fixation technique using FiberWire.

An improved method for cable grip fixation of the greater trochanter after trochanteric slide osteotomy.

This study proposes a novel method for reattachment of the trochanteric slide osteotomy. The strength of this new fixation system was compared to established configurations. Fifteen sawbone femurs were used. Our configuration used cables above and below the lesser trochanter with a third cable around the shaft of the femur while passing the loose ends through the inferior hole of the cable grip. Displacement of the trochanter was measured with increasing load. Force required for catastrophic failure was also measured. The 3-cable construct resulted in significantly less displacement with increasing load and required a larger force to cause failure (1 cm and 2 cm). We theorize that our configuration produces a biomechanically stronger construct than previously used methods.

Modular femoral stem-sleeve junction failure after primary total hip arthroplasty.

The total hip prosthesis has evolved from the initial monoblock system developed by Charnley. Modularity of both the femoral and acetabular components, which allows the surgeon to assemble the prostheses just before or during the course of implantation, has now become standard. Modularity increases the number of implant parameter variables, allowing semicustom devices to be constructed. Component interfaces, however, are subject to significant stresses, micromotion manifesting as fretting, may produce wear debris, and at times may experience macromotion leading to catastrophic failure. We report 3 cases of stem-sleeve junction failure in otherwise uncomplicated primary total hip arthroplasties. Two of the failures occurred in the S-ROM (Joint Medical Products, Stamford, Conn) femoral stem design and the other in an Apex stem (Omni Life Science, Raynham, Mass). To our knowledge, there have been no previous reports of clinical failures at femoral stem-sleeve junction.

The effect of sonification display pulse rate and reliability on operator trust and perceived workload during a simulated patient monitoring task.

The present study investigated the effects of sonification pulse rate and sensor reliability on operator trust and mental workload. Processing resources and operator trust were sensitive to both pulse rate and sensor reliability. These findings suggest that setting pulse rates to 60 pulses per min may have considerable benefits in critical task environments.

Tracking acid mine-drainage in Southeast Arizona using GIS and sediment delivery models.

This study investigates the application of models traditionally used to estimate erosion and sediment deposition to assess the potential risk of water quality impairment resulting from metal-bearing materials related to mining and mineralization. An integrated watershed analysis using Geographic Information Systems (GIS) based tools was undertaken to examine erosion and sediment transport characteristics within the watersheds. Estimates of stream deposits of sediment from mine tailings were related to the chemistry of surface water to assess the effectiveness of the methodology to assess the risk of acid mine-drainage being dispersed downstream of abandoned tailings and waste rock piles. A watershed analysis was preformed in the Patagonia Mountains in southeastern Arizona which has seen substantial mining and where recent water quality samples have reported acidic surface waters. This research demonstrates an improvement of the ability to predict streams that are likely to have severely degraded water quality as a result of past mining activities.

Bone morphogenetic proteins and Smad expression in ovine tendon-bone healing.

PURPOSE: Bone morphogenetic proteins (BMPs) are being developed to improve tendon-bone healing. To do this, it is essential to understand the endogenous expression of BMPs and their downstream signal transduction factors, Smads, during tendon-bone healing. METHODS: An extra-articular patellar tendon-bone healing ovine model was set up, and histologic evaluation of the healing progress at the tendon-bone interface at 1, 2, 3, and 6 weeks was performed. Immunohistochemical staining of BMP-2, BMP-7, Smad1, Smad4, and Smad5 was carried out in all sections. RESULTS: The model revealed formation of a loose granuloma tissue layer between the tendon and bone at 1 week, remodeling starting at 2 weeks, and Sharpey-like collagen fiber formation at 3 and 6 weeks. All detected factors were elevated at the tendon-bone interface during healing, and the expression peaked at 2 to 3 weeks. The cells involved were osteoblastic-like cells, osteoclastic-like cells, mesenchymal cells, and fibroblasts. BMP-7 staining was mainly at the interface close to the bony side, whereas BMP-2 expression shifted to the tendon side at 6 weeks. The expression pattern of Smad1 and Smad5 was similar to that of BMP-7. Smad1 was also found to be expressed in osteoclastic-like cells at 1 and 2 weeks. Smad4 expression was the highest among all of the factors at all time points. CONCLUSIONS: The data suggest that endogenous BMP-2 and BMP-7 participate in tendon-bone healing and their functions involve their downstream signal transduction mediators, Smad1, Smad4, and Smad5. CLINICAL RELEVANCE: The temporal expression of BMPs should be considered when setting up therapeutic strategies using BMPs.

The role of alarm signal duration as a cue for alarm validity.

Researchers have isolated several variables that moderate the degrading effects of alarm mistrust on alarm reactions. We examined how alarm duration influences reactions to alarms of varying true alarm rates. In Experiment one, 45 psychology students performed a complex psychomotor task while reacting to an alarm system generating short- and long-duration signals. We predicted that participants would consider long-duration alarms more valid and would respond more to them despite the true alarm rate. Results supported both expectations. In addition to these findings, participants believed that true alarm rate influenced their response decisions more than duration even though true alarm rate did not affect actual response frequency. In Experiment two, 40 students reacted to short- and long-duration alarms originating from unique systems. Results showed some participants relied on duration, whereas others used true alarm rate, responded extremely, or combined strategies. Overall, results suggest signal duration is an important influence, but that increased task complexity may lead operators to adopt other reaction strategies.

Comparison of a virtual reality simulator and simulated limbs for phlebotomy training.

The current study compared the CathSim virtual reality simulator with simulated limbs for phlebotomy training. In the first experiment, medical students completed two 1-hour training sessions using 1 of the 2 methods. Afterward, the students' performance was assessed with both simulated limbs and genuine patients. The results showed that students trained with the simulated limbs achieved higher scores on both the posttest and the field test with actual patients than those trained on the CathSim system. In the second study, graduate students practiced with the CathSim system for 5 hours. The results showed a significant improvement in scores from pretest to posttest for these students. However, even after extended practice, their final scores did not differ from those of the medical students in the first experiment. Critical differences in design characteristics between the 2 systems may explain these findings. Although the authors observed a clear advantage for simulated limbs over the CathSim system, neither system faithfully represents all of steps needed to perform the procedure. Thus, training decisions may require that the unique advantages afforded by each system be considered.

The efficacy of a medical virtual reality simulator for training phlebotomy.

OBJECTIVE: The present study compared the effectiveness of a virtual reality (VR) simulator for training phlebotomy with that of a more traditional approach using simulated limbs. BACKGROUND: Phlebotomy, or drawing blood, is one of the most common medical procedures; yet, there are no universal standards for training and assessing performance. The absence of any standards can lead to injuries and inaccurate test results if the procedure is improperly performed. METHOD: Twenty 3rd-year medical students were trained under one of the two methods and had their performance assessed with a 28-item checklist. RESULTS: The results showed that performance improvements were limited to those who trained with the simulated limbs, and a detailed comparison of the two systems revealed several functional and physical differences that may explain these findings. CONCLUSION: Participants trained with simulated limbs performed better than those trained with a VR simulator; however, the metrics recorded by the VR system may address some aspects of performance that could eventually prove beneficial. APPLICATION: The present study highlights the potential for medical simulators to improve patient safety by enabling trainees to practice procedures on devices instead of patients. Applications of this research include training, performance assessment, and design of simulator systems.

Determining the efficacy of an immersive trainer for arthroscopy skills.

The present study examined the effectiveness of an immersive arthroscopic simulator for training naive participants to identify major anatomical structures and manipulate the arthroscope and probe. Ten psychology graduate students engaged in five consecutive days of practice sessions with the arthroscopic trainer. Following each session, participants were tested to see how quickly and accurately they could identify 10 anatomical landmarks and manipulate the arthroscope and probe. The results demonstrated steady learning on both tasks. For the anatomy task, participants correctly identified an average of 7.7 out of 10 structures correctly in the first session and 9.5 in the last. During the manipulation task, participants collided 53.5 times with simulated tissues in the first session and 13.2 times during the final session. Participants (n=9) also demonstrated minimal performance degradation when tested 4 weeks later. These data suggest that the immersive arthroscopic trainer might be useful as an initial screening or training tool for beginning medical students.

Assessing surgical skill training under hazardous conditions in a virtual environment.

The present study examined the performance of a surgical procedure under simulated combat conditions. Eleven residents performed a cricothyroidotomy on a mannequin-based simulator in a fully immersive virtual environment running a combat simulation with a virtual sniper under both day and night time lighting conditions. The results showed that completion times improved between the first and second attempt and that differences between day and night time conditions were minimal. However, three participants were killed by the virtual sniper before completing the procedure. These results suggest that some participants' ability to allocate attention to the task and their surroundings was inappropriate even under simulated hazardous conditions. Further, this study shows that virtual environments offer the chance to study a wider variety of medical procedures performed under an unlimited number of conditions.