Front-Line Health Care Workers' COVID-19 Infection Contamination Risks: A Human Factors and Risk Analysis Study of Personal Protective Equipment

Infectious risks escalate with complex donning and doffing personal protective equipment (PPE) protocols. Recent studies suggest that PPE donning and doffing behaviors that deviate from protocol during PPE reuse compounded the risks of health care worker (HCW) self-contamination. This study quantified the occurrence of behaviors associated with known risks in PPE use and reuse. We conducted a prospective study of emergency department HCWs and video-recorded PPE donning and doffing 5 times in simulated patient encounters. Trained coders recorded HCW behaviors according to an evidence-based guide. All 28 participants deviated from the Centers for Disease Control and Prevention (CDC) sanctioned donning and doffing protocol order, and most were documented to have (92.85%) self-contaminated at least once during each simulated clinical encounter. Behaviors that compounded self-contamination due to PPE reuse were also observed. Wide variation in PPE donning and doffing behaviors was found among front-line, experienced HCWs. Future work is needed to determine which deviations put HCWs at increased risk for accidental self-contamination and what changes are needed to the CDC protocol for protecting HCW from infections.

An investigation into emergency medicine resident cricothyrotomy competency: Is three the magic number?

Objectives

Cricothyrotomy is a high-stakes emergency procedure. Because the procedure is rare, simulation is often used to train residents. The Accreditation Council for Graduate Medical Education (ACGME) requires performance of three cricothyrotomies during residency, but the optimal number of training repetitions is unknown. Additional repetitions beyond three could increase proficiency, though it is unknown whether there is a threshold beyond which there is no benefit to additional repetition. The objective of this study was to establish a minimum number of simulated cricothyrotomy attempts beyond which additional attempts did not increase proficiency.

Methods

This was a prospective, observational study conducted over 3 years at the simulation center of an academic emergency medicine residency program. Participants were residents participating in a cricothyrotomy training as part of a longitudinal airway curriculum course. The primary outcome was time to successful completion of the procedure as first-year residents. Secondary outcomes included time to completion as second- and third-year residents. Procedure times were plotted as a function of attempt number. Data were analyzed using descriptive statistics, repeated-measures analysis of variance, and correlation analysis. Preprocedure surveys collected further data regarding procedure experience, confidence, and comfort.

Results

Sixty-nine first-year residents participated in the study. Steady improvement in time to completion was seen through the first six attempts (from a mean of 75 to 41 sec), after which no further significant improvement was found. Second- and third-year residents initially demonstrated slower performance than first-year residents but rapidly improved to surpass their first-year performance. Resident mean times at five attempts were faster with each year of residency (first-year 48 sec, second-year 30 sec, third-year 24 sec). There was no statistically significant correlation between confidence and time to complete the procedure.

Conclusions

Additional repetition beyond the ACGME-endorsed three cricothyrotomy attempts may help increase proficiency. Periodic retraining may be important to maintain skills.

Effect of inclined positioning on first-pass success during endotracheal intubation: a systematic review and meta-analysis

BACKGROUND

Endotracheal intubation is a high-risk procedure. Optimisation of all aspects of the procedure, including patient positioning, is important to facilitate success and minimise complications. The objective of this systematic review was to determine the association between inclined patient positioning and first-pass success and other clinically important outcomes among patients undergoing endotracheal intubation.

METHODS

A search of PubMed, CINAHL, SCOPUS, EMBASE and Cochrane, from inception through October 2020 was conducted. Studies were assessed independently by two authors to determine eligibility for inclusion. Included studies were any randomised or observational study that compared supine to inclined patient positioning for endotracheal intubation and assessed one of our predefined outcomes. Simulation studies were excluded. Study results were meta-analysed using a random effects model. The quality of the evidence for outcomes of interest was assessed using the Grading of Recommendations, Assessment, Development and Evaluations approach.

RESULTS

A total of 5113 studies were identified, of which 10 studies representing 18 371 intubations were included for meta-analysis. There was no statistically significant difference in the primary outcome of first-pass success rate (relative risk 1.02, 95% CI 0.98 to 1.05) or secondary outcomes of oesophageal intubation, glottic view, hypotension, hypoxaemia, mortality or peri-intubation arrest. Likewise, there were no statistically significant differences in any of the outcomes in predefined subgroup analyses of randomised controlled trials, intubations in acute settings or intubations performed with >45 degrees of incline. Overall quality of evidence was rated as low or very low for most outcomes.

CONCLUSIONS

This systematic review and meta-analysis found no evidence of benefit or harm with inclined versus supine patient positioning during endotracheal intubation in any setting.

Medical students rise to the COVID-19 vaccine challenge

Abstract Background The COVID-19 pandemic disrupted medical student education at a time when they were most eager to step up and help with the pandemic response. Indiana University School of Medicine (IUSM) leveraged an existing relationship with the Indiana Department of Health (IDOH) and the major healthcare systems in the state to assist with the state’s mass vaccination campaign. In this paper, we describe the development and implementation of a medical student volunteer program and highlight the main components of integrating community service programs into medical education. Methods IUSM appointed a taskforce to create a state-wide IUSM Medical Student Volunteer Vaccinator program to quickly train and deploy a medical student volunteer workforce. This taskforce was charged with (1) creating and delivering asynchronous and in-person training curriculum for all nine regional campuses and (2) coordinating medical student volunteerism for vaccine delivery across the state of Indiana. Results A total of 517 of 739 targeted medical students were fully trained in vaccine administration and contributed to over 2,000 hours of volunteer community service and delivered over 15,000 vaccine doses across the state of Indiana. Students also participated in other essential vaccination delivery roles, such as screening and registration of patients, exit monitoring, and pre-calling patients to remind them of their appointments. Conclusions Community service should be a critical component of medical student education. The IUSM Medical Student Volunteer Vaccinator program is an example of what the collaboration between medical schools, state health departments, and healthcare systems can achieve. This model can not only be disseminated to other medical school / healthcare system dyads for mass vaccination efforts but can also be expanded to other public health initiatives such as health screening programs, health education programs, contact tracing programs, community outreach programs, and global health initiatives.   Conflicts of interest: None

Improved simulated ventilation with a novel tidal volume and peak inspiratory pressure controlling bag valve mask: A pilot study

Introduction

The dangers of hyperventilation during resuscitation are well known. Traditional bag valve mask (BVM) devices rely on end users to control tidal volume (V_t), rate, and peak inspiratory pressures (PIP) of ventilation. The Butterfly BVM (BBVM) is a novel device intending to give greater control over these parameters. The objective of this pilot study was to compare the BBVM against a traditional device in simulated resuscitations.

Methods

Senior emergency medicine residents and fellows participated in a three-phase simulation study. First, participants used the Ambu Spur II BVM in adult and pediatric resuscitations. V_t, PIP, and rate were recorded. Second, participants repeated the resuscitations after a brief introduction to the BBVM. Third, participants were given a longer introduction to the BBVM and were tested on their ability to adjust its various settings.

Results

Nineteen participants were included in the adult arm of the study, and 16 in the pediatric arm. The BBVM restricted V_t delivered to a range of 4-8 ml/kg vs 9 ml/kg and 13 ml/kg (Ambu adult and Ambu pediatric respectively). The BBVM never exceeded target minute ventilations while the Ambu BVMs exceeded target minute ventilation in 2 of 4 tests. The BBVM failed to reliably reach higher PIP targets in one test, while the pediatric Ambu device had 76 failures of excessive PIP compared to 2 failures by the BBVM.

Conclusion

The BBVM exceeded the Ambu Spur II in delivering appropriate V_ts and in keeping PIPs below target maximums to simulated adult and pediatric patients in this pilot study.

The Dangers of Reused Personal Protective Equipment: Healthcare Workers and Workstation Contamination

Background

Personal protective equipment (PPE) is essential to protect healthcare workers (HCWs). The practice of reusing PPE poses high levels of risk for accidental contamination by HCWs. Scarce medical literature compares practical means or methods for safe reuse of PPE while actively caring for patients.

Methods

In this study, observations were made of 28 experienced clinical participants performing five donning and doffing encounters while performing simulated full evaluations of patients with coronavirus disease 2019. Participants' N95 respirators were coated with a fluorescent dye to evaluate any accidental fomite transfer that occurred during PPE donning and doffing. Participants were evaluated using blacklight after each doffing encounter to evaluate new contamination sites, and were assessed for the cumulative surface area that occurred due to PPE doffing. Additionally, participants' workstations were evaluated for contamination.

Results

All participants experienced some contamination on their upper extremities, neck and face. The highest cumulative area of fomite transfer risk was associated with the hook and paper bag storage methods, and the least contamination occurred with the tabletop storage method. Storing a reused N95 respirator on a tabletop was found to be a safer alternative than the current recommendation of the US Centers for Disease Control and Prevention to use a paper bag for storage. All participants donning and doffing PPE were contaminated.

Conclusion

PPE reusage practices pose an unacceptably high level of risk of accidental cross-infection contamination to healthcare workers. The current design of PPE requires complete redesign with improved engineering and usability to protect healthcare workers.

Improving Pediatric Diabetic Ketoacidosis Management in Community Emergency Departments Using a Simulation-Based Collaborative Improvement Program

OBJECTIVES

The majority of pediatric patients with diabetic ketoacidosis (DKA) present to community emergency departments (CEDs) that are less prepared to care for acutely ill children owing to low pediatric volume and limited pediatric resources and guidelines. This has impacted the quality of care provided to pediatric patients in CEDs. We hypothesized that a simulation-based collaborative program would improve the quality of the care provided to simulated pediatric DKA patients presenting to CEDs.

METHODS

This prospective interventional study measured adherence of multiprofessional teams caring for pediatric DKA patients preimplementation and postimplementation of an improvement program in simulated setting. The program consisted of (a) a postsimulation debriefing, (b) assessment reports, (c) distribution of educational materials and access to pediatric resources, and (d) ongoing communication with the academic medical center (AMC). All simulations were conducted in situ (in the CED resuscitation bay) and were facilitated by a collaborative team from the AMC. A composite adherence score was calculated using a critical action checklist. A mixed linear regression model was performed to examine the impact of CED and team-level variables on the scores.

RESULTS

A total of 91 teams from 13 CEDs participated in simulated sessions. There was a 22-point improvement of overall adherence to the DKA checklist from the preintervention to the postintervention simulations. Six of 9 critical checklist actions showed statistically significant improvement. Community emergency departments with medium pediatric volume showed the most overall improvement. Teams from CEDs that are further from the AMC showed the least improvement from baseline.

CONCLUSIONS

This study demonstrated a significant improvement in adherence to pediatric DKA guidelines in CEDs across the state after execution of an in situ simulation-based collaborative improvement program.

Stress and resident interdisciplinary team performance: Results of a pilot trauma simulation program

BACKGROUND

Excessive stress negatively impacts surgical residents' technical performance. The effect of stress on trainee nontechnical skills, however, is less well studied. Given that nontechnical skills are known to impact clinical performance, the purpose of this study was to assess the relationship between residents' perceived stress and nontechnical skills during multidisciplinary trauma simulations.

METHODS

First-year surgery and emergency medicine residents voluntarily participated in this study. Residents participated in 3 trauma simulations across 2 training sessions in randomly assigned teams. Each team's nontechnical skills were evaluated by faculty using the Trauma Nontechnical Skills scale. The Trauma Nontechnical Skills scale consists of 5 items: leadership, cooperation, communication, assessment, and situation awareness/coping with stress. After each scenario, residents completed the 6-item version of the State-Trait Anxiety Inventory and the Surgery Task Load Index to detail their perceived stress and workload during scenarios. Linear regressions were run to assess relationships between stress, workload, and nontechnical skills.

RESULTS

Twenty-five residents participated in the first simulation day, and 24 residents participated in the second simulation day. Results from regressions revealed that heightened stress and workload predicted significantly lower nontechnical skills performance during trauma scenarios. In regard to specific aspects of nontechnical skills, residents' heightened stress and workload predicted statistically significant lower situation awareness and decision-making during trauma scenarios.

CONCLUSION

Residents' perceived stress and workload significantly impaired their nontechnical skills during trauma simulations. This finding highlights the need to offer stress management and performance-optimizing mental skills training to trainees to lower their stress and optimize nontechnical skills performance during challenging situations.

Effect of an Aerosol Box on Intubation in Simulated Emergency Department Airways: A Randomized Crossover Study

INTRODUCTION

The use of transparent plastic aerosol boxes as protective barriers during endotracheal intubation has been advocated during the severe acute respiratory syndrome coronavirus 2 pandemic. There is evidence of worldwide distribution of such devices, but some experts have warned of possible negative impacts of their use. The objective of this study was to measure the effect of an aerosol box on intubation performance across a variety of simulated difficult airway scenarios in the emergency department.

METHODS

This was a randomized, crossover design study. Participants were randomized to intubate one of five airway scenarios with and without an aerosol box in place, with randomization of intubation sequence. The primary outcome was time to intubation. Secondary outcomes included number of intubation attempts, Cormack-Lehane view, percent of glottic opening, and resident physician perception of intubation difficulty.

RESULTS

Forty-eight residents performed 96 intubations. Time to intubation was significantly longer with box use than without (mean 17 seconds [range 6-68 seconds] vs mean 10 seconds [range 5-40 seconds], p <0.001). Participants perceived intubation as being significantly more difficult with the aerosol box. There were no significant differences in the number of attempts or quality of view obtained.

CONCLUSION

Use of an aerosol box during difficult endotracheal intubation increases the time to intubation and perceived difficulty across a range of simulated ED patients.

Factors that Contribute to Resident Teaching Effectiveness

Background

One of the key components of residency training is to become an educator. Resident physicians teach students, advanced practice providers, nurses, and even faculty on a daily basis.

Objective

The goal of this study was to identify the objective characteristics of residents, which correlate with perceived overall teaching effectiveness.

Methods

We conducted a one-year, retrospective study to identify factors that were associated with higher resident teaching evaluations. Senior emergency medicine (EM) teaching residents are evaluated by medical students following clinical teaching shifts. Eighteen factors pertaining to resident teaching effectiveness were chosen. Two items from the medical students' evaluations were analyzed against each factor: teaching effectiveness was measured on a five-point Likert scale and an overall teaching score (1-75).

Results

A total of 46 EM residents and 843 medical student evaluations were analyzed. The ACGME milestones for systems-based practice (p = 0.02) and accountability (p = 0.05) showed a statistically significant association with a rating of “five” on the Likert scale for teaching effectiveness. Three other ACGME milestones, systems-based practice (p = 0.01), task switching (p = 0.04), and team management (p = 0.03) also showed a statically significant association of receiving a score of 70 or greater on the overall teaching score.

Conclusion

Residents with higher performance associated with system management and accountability were perceived as highly effective teachers. USMLE and in-service exams were not predictive of higher teaching evaluations. Our data also suggest that effective teachers are working in both academic and community settings, providing a potential resource to academic departments and institutions.

Failure of an Educational Intervention to Improve Consultation and Implications for Healthcare Consultation

Introduction: Consultation of another physician for his or her specialized expertise regarding a patient’s care is a common occurrence in most physicians’ daily practice, especially in the emergency department (ED). Therefore, the ability to communicate effectively with another physician during a patient consultation is an essential skill. However, there has been limited research on a standardized method for a physician to physician consultation with little guidance on teaching consultations to physicians in training. The objective of our study was to measure the effect of a structured consultation intervention on both content standardization and quality of medical student consultations.

Methods: Senior medical students were assessed on a required emergency medicine rotation with a physician phone consultation during a standardized, simulated chest pain case. The intervention groups received a standard consult checklist as part of their orientation to the rotation, followed by a video recording of a good consult call and a bad consult call with commentary from an emergency physician. The intervention was given to students every other month, alternating with a control group who received no additional education. Recordings were reviewed by three second-year internal medicine residents pursuing a fellowship in cardiology. Each recording was evaluated by two of the three reviewers and scored using a standardized checklist.

Results: Providing a standardized consultation intervention did not improve students’ ability to communicate with consultants. In addition, there was variability between evaluators in regards to how they received the same information and how they perceived the quality of the same recorded consultation calls. Evaluator inter-rater reliability (IRR) was poor on the questions of 1) would you have any other questions of the student calling the consult and 2) did the student calling the consult provide an accurate account of information and case detail. The IRR was also poor on objective data such as whether the student stated their name.

Conclusions: A brief intervention may not be enough to change complex behavior such as a physician to physician consultant communication. Importantly, despite consultants listening to the same audio recordings, the information was processed differently. Future investigations should focus on both those delivering as well as those receiving a consultation.

Human Factors and Simulation in Emergency Medicine

This consensus group from the 2017 Academic Emergency Medicine Consensus Conference "Catalyzing System Change through Health Care Simulation: Systems, Competency, and Outcomes" held in Orlando, Florida, on May 16, 2017, focused on the use of human factors (HF) and simulation in the field of emergency medicine (EM). The HF discipline is often underutilized within EM but has significant potential in improving the interface between technologies and individuals in the field. The discussion explored the domain of HF, its benefits in medicine, how simulation can be a catalyst for HF work in EM, and how EM can collaborate with HF professionals to effect change. Implementing HF in EM through health care simulation will require a demonstration of clinical and safety outcomes, advocacy to stakeholders and administrators, and establishment of structured collaborations between HF professionals and EM, such as in this breakout group.

Changing Systems Through Effective Teams: A Role for Simulation

Teams are the building blocks of the healthcare system, with growing evidence linking the quality of healthcare to team effectiveness, and team effectiveness to team training. Simulation has been identified as an effective modality for team training and assessment. Despite this, there are gaps in methodology, measurement, and implementation that prevent maximizing the impact of simulation modalities on team performance. As part of the 2017 Academic Emergency Medicine Consensus Conference "Catalyzing System Change Through Health Care Simulation: Systems, Competency, and Outcomes," we explored the impact of simulation on various aspects of team effectiveness. The consensus process included an extensive literature review, group discussions, and the conference "workshop" involving emergency medicine physicians, medical educators, and team science experts. The objectives of this work were to: 1) explore the antecedents and processes that support team effectiveness, 2) summarize the current role of simulation in developing and understanding team effectiveness, and 3) identify research targets to further improve team-based training and assessment, with the ultimate goal of improving healthcare systems.

Cross-over study of novice intubators performing endotracheal intubation in an upright versus supine position

There are a number of potential physical advantages to performing orotracheal intubation in an upright position. The objective of this study was to measure the success of intubation of a simulated patient in an upright versus supine position by novice intubators after brief training. This was a cross-over design study in which learners (medical students, physician assistant students, and paramedic students) intubated mannequins in both a supine (head of the bed at 0°) and upright (head of bed elevated at 45°) position. The primary outcome of interest was successful intubation of the trachea. Secondary outcomes included log time to intubation, Cormack-Lehane view obtained, Percent of Glottic Opening score, provider assessment of difficulty, and overall provider satisfaction with the position. There were a total of 126 participants: 34 medical students, 84 physician assistant students, and 8 paramedic students. Successful tracheal intubation was achieved in 114 supine attempts (90.5 %) and 123 upright attempts (97.6 %; P = 0.283). Upright positioning was associated with significantly faster log time to intubation, higher likelihood of achieving Grade I Cormack-Lehane view, higher Percent of Glottic Opening score, lower perceived difficulty, and higher provider satisfaction. A subset of 74 participants had no previous intubation training or experience. For these providers, there was a non-significant trend toward improved intubation success with upright positioning vs supine positioning (98.6 % vs. 87.8 %, P = 0.283). For all secondary outcomes in this group, upright positioning significantly outperformed supine positioning.

Effect of Socioeconomic Status Bias on Medical Student-Patient Interactions Using an Emergency Medicine Simulation

OBJECTIVES

Implicit bias in clinical decision making has been shown to contribute to healthcare disparities and results in negative patient outcomes. Our objective was to develop a high-fidelity simulation model for assessing the effect of socioeconomic status (SES) on medical student (MS) patient care.

METHODS

Teams of MSs were randomly assigned to participate in a high-fidelity simulation of acute coronary syndrome. Cases were identical with the exception of patient SES, which alternated between a low-SES homeless man and a high-SES executive. Students were blinded to study objectives. Cases were recorded and scored by blinded independent raters using 24 dichotomous items in the following domains: 13 communication, six information gathering, and five clinical care. In addition, quantitative data were obtained on the number of times students performed the following patient actions: acknowledged patient by name, asked about pain, generally conversed, and touching the patient. Fisher's exact test was used to test for differences between dichotomous items. For continuous measures, group differences were tested using a mixed-effects model with a random effect for case to account for multiple observations per case.

RESULTS

Fifty-eight teams participated in an equal number of high- and low-SES cases. MSs asked about pain control more often (p = 0.04) in patients of high SES. MSs touched the low-SES patient more frequently (p = 0.01). There were no statistically significant differences in clinical care or information gathering measures.

CONCLUSIONS

This study demonstrates more attention to pain control in patients with higher SES as well as a trend toward better communication. Despite the differences in interpersonal behavior, quantifiable differences in clinical care were not seen. These results may be limited by sample size, and larger cohorts will be required to identify the factors that contribute to SES bias.

Medical students' perception of residents as teachers: comparing effectiveness of residents and faculty during simulation debriefings

BACKGROUND

Simulation can enhance undergraduate medical education. However, the number of faculty facilitators needed for observation and debriefing can limit its use with medical students. The goal of this study was to compare the effectiveness of emergency medicine (EM) residents with that of EM faculty in facilitating postcase debriefings.

METHODS

The EM clerkship at Indiana University School of Medicine requires medical students to complete one 2-hour mannequin-based simulation session. Groups of 5 to 6 students participated in 3 different simulation cases immediately followed by debriefings. Debriefings were led by either an EM faculty volunteer or EM resident volunteer. The Debriefing Assessment for Simulation in Healthcare (DASH) participant form was completed by students to evaluate each individual providing the debriefing.

RESULTS

In total, 273 DASH forms were completed (132 EM faculty evaluations and 141 EM resident evaluations) for 7 faculty members and 9 residents providing the debriefing sessions. The mean total faculty DASH score was 32.42 and mean total resident DASH score was 32.09 out of a possible 35. There were no statistically significant differences between faculty and resident scores overall (P  =  .36) or by case type (P trauma  =  .11, P medical  =  .19, P pediatrics  =  .48).

CONCLUSIONS

EM residents were perceived to be as effective as EM faculty in debriefing medical students in a mannequin-based simulation experience. The use of residents to observe and debrief students may allow additional simulations to be incorporated into undergraduate curricula and provide valuable teaching opportunities for residents.

Modulation of hematopoietic stem/progenitor cell engraftment by transforming growth factor beta

OBJECTIVE

To investigate if cell cycle progression plays a role in modulating the engraftment potential of mouse hematopoietic stem and progenitor cells (HSPC).

MATERIALS AND METHODS

HSPC were isolated from adult mouse bone marrow, cultured in vitro under conditions promoting cell cycle arrest, and subsequently were evaluated for cell cycle status, clonogenic activity, and transplant potential. RESULTS In the presence of steel factor (STL) as a survival cytokine, transforming growth factor beta (TGF-beta) increased the G0/G1 fraction of cycling progenitor cells (Rh(high)) after a 20-hour culture. Clonogenic activity of quiescent long-term repopulating (Rh(low)) HSPC was unaffected by this culture, whereas clonogenic potential of Rh(high) cells decreased by about 30%. In competitive repopulation assays, Rh(low) cells cultured in STL + TGF-beta engrafted better than cells cultured in STL alone. However, culture in STL + TGF-beta did not overcome the failure of Rh(high) cells to engraft after transplant. We also utilized a two-stage culture system to first induce proliferation of Rh(low) HSPC by a 48-hour culture in STL + interleukin 6 + Flt-3 ligand, followed by shifting the culture to STL + TGF-beta for 24 hours to induce cycle arrest. A competitive repopulation assay demonstrated a relative decrease in repopulating potential in cultures that were cycle arrested compared to those that were not.

CONCLUSION

Cell cycle progression by itself cannot account for the decrease in repopulating potential that is observed after ex vivo expansion. Other determinants of engraftment must be identified to facilitate the transplantation of cultured HSPC.

Paradigm shifts in stem-cell biology

Hematopoiesis is a physiologic process that can be transplanted by intravenous infusion of stem and progenitor cells. Because these cells contribute to blood production over a lifespan, they are attractive targets for cell-based therapies of hematologic malignancies and genetic defects. A more complete understanding of the basic biology of hematopoiesis will accelerate our progress toward the clinical goal of improved stem-cell-based therapies. Many advances in recent years have brought us closer to that goal and have, in addition, challenged a number of dogmatic notions about hematopoiesis. Three of these advances are briefly addressed here: (1) an emerging appreciation of the complex relationship between cell-cycle status, engraftment potential, and self-renewal in the hematopoietic system; (2) the demonstration of new progenitor populations and lineage relationships in early hematopoietic development; and (3) a reanalysis of the embryonic origins of hematopoiesis. These and other advances are allowing the mysteries of hematopoiesis to be unlocked at a pace that was unimaginable just a few years ago.

(R)evolutionary considerations in hematopoietic development

Evolutionary aspects of three characteristics of the mammalian hematopoietic system are considered in the context of both established and recent data. First, the lineage relationships among early members of the hematopoietic hierarchy are reconsidered in a tripartite model proposing lineage segregation based on vascular function, innate immunity, and acquired immunity on an evolutionary time scale. Second, the observation of two stem cell populations that differ in cell cycle status is considered as an evolved mechanism to enhance survival of the species in response to exposure to environmental toxins. Finally, the mobilization of hematopoietic stem cells into the peripheral circulation is proposed to be a mechanism for rapid dissemination of myeloid function during acute bacterial infections. These revolutionary hypotheses challenge some conventional concepts of stem cell biology, and provide an evolutionary context for considering mammalian hematopoiesis.

Rhodamine-123 staining in hematopoietic stem cells of young mice indicates mitochondrial activation rather than dye efflux

Low-intensity fluorescence of rhodamine-123 (Rh-123) discriminates a quiescent hematopoietic stem cell (HSC) population in mouse bone marrow, which provides stable, long-term hematopoiesis after transplantation. Rh-123 labels mitochondria with increasing intensity proportional to cellular activation, however the intensity of staining also correlates with the multidrug resistance (MDR) phenotype, as Rh-123 is a substrate for P-glycoprotein (P-gp). To address the mechanisms of long-term repopulating HSC discrimination by Rh-123, mouse bone marrow stem and progenitor cells were isolated based on surface antigen expression and subsequently separated into subsets using various fluorescent probes sensitive to mitochondrial characteristics and/or MDR function. We determined the cell cycle status of the separated populations and tested for HSC function using transplantation assays. Based on blocking studies using MDR modulators, we observed little efflux of Rh-123 from HSC obtained from young (3- to 4-week-old) mice, but significant efflux from HSC derived from older animals. A fluorescent MDR substrate (Bodipy-verapamil, BodVer) and Rh-123 both segregated quiescent cells into a dim-staining population, however Rh-123-based separations resulted in better enrichment of HSC function. Similar experiments using two other fluorescent probes with specificity for either mitochondrial mass or membrane potential indicated that mitochondrial activation is more important than either mitochondrial mass or MDR function in defining HSC in young mice. This conclusion was supported by morphologic studies of cell subsets separated by Rh-123 staining.

The effect of a thirty per cent reduction in physician fees on Medicaid surgery rates in Massachusetts

In this paper, we use an interrupted time series analysis to assess the effect of a 30 per cent reduction in the Medicaid reimbursement fee for physician services on the rate at which eight elective surgical procedures were performed in the Massachusetts Medicaid population. Tonsillectomy/adenoidectomy is the only procedure in which there was a statistically significant decline in the rate of surgery in most areas of the state following the fee cut. There is some evidence of an increase in the rate of disc surgeries/spinal fusions. The rate of other procedures increased in some areas of the state and decreased in other areas in the period after the fee cut.