Management Considerations for Air Medical Transport Programs Transfusing RhD-Positive Red Blood Cell-Containing Products to Females of Childbearing Potential.

Recent years have seen increased discussion surrounding the benefits of damage control resuscitation, prehospital transfusion (PHT) of blood products, and the use of whole blood over component therapy. Concurrent shortages of blood products with the desire to provide PHT during air medical transport have prompted reconsideration of the traditional approach of administering RhD-negative red cell-containing blood products first-line to females of childbearing potential (FCPs). Given that only 7% of the US population has blood type O negative and 38% has O positive, some programs may be limited to offering RhD-positive blood products to FCPs. Adopting the practice of giving RhD-positive blood products first-line to FCPs extends the benefits of PHT to such patients, but this practice does incur the risk of future hemolytic disease of the fetus and newborn (HDFN). Although the risk of future fetal mortality after an RhD-incompatible transfusion is estimated to be low in the setting of acute hemorrhage, the number of FCPs who are affected by this disease will increase as more air medical transport programs adopt this practice. The process of monitoring and managing HDFN can also be time intensive and costly regardless of the rates of fetal mortality. Air medical transport programs planning on performing PHT of RhD-positive red cell-containing products to FCPs should have a basic understanding of the pathophysiology, prevention, and management of hemolytic disease of the newborn before introducing this practice. Programs should additionally ensure there is a reliable process to notify receiving centers of potentially RhD-incompatible PHT because alloimmunization prophylaxis is time sensitive. Facilities receiving patients who have had PHT must be prepared to identify, counsel, and offer alloimmunization prophylaxis to these patients. This review aims to provide air medical transport professionals with an understanding of the pathophysiology and management of HDFN and provide a template for the early management of FCPs who have received an RhD-positive red cell-containing PHT. This review also covers the initial workup and long-term anticipatory guidance that receiving trauma centers must provide to FCPs who have received RhD-positive red cell-containing PHT.

Helicopter emergency medical services (HEMS) response to out-of-hospital cardiac arrest (OHCA) in the United States.

Introduction: Helicopter emergency medical services (HEMS) are used in the United States and globally to respond to patients with critical illness and victims of traumatic injury. Relatively limited research has examined their role in responding to out-of-hospital cardiac arrests (OHCA) in the United States. In this study, we compared OHCA treated by HEMS units with cardiac arrests treated by ground ambulances. Methods: We queried a large national-level database of emergency medical services (EMS) activations in the United States (NEMSIS). Inclusion criteria were OHCA activations between January 1, 2022 and December 31, 2022 treated by either HEMS or ground ambulance. Key arrest data from both groups were then compared. Interfacility transfers and cardiac arrests after EMS arrival were excluded. Results: A total of 1,233 cardiac arrests treated by HEMS and 341,096 cardiac arrests treated by ground ambulances met inclusion criteria. Comparing the two groups, cardiac arrests with HEMS response were more likely to be male (66.7% vs. 62.8%, p < 0.01), White (50.2% vs. 45.7%, p < 0.01), under 18 years old (10.9% vs. 2.7%, p < 0.001), associated with traumatic injury (19.1% vs. 5.7%, p < 0.001), witnessed (72.7% vs. 37.3%, p < 0.001), and initially-shockable (24.7% vs. 11.1%, p < 0.001). Conclusion: Our comparison of cardiac arrests treated by HEMS with cardiac arrests treated by ground ambulance reveals significant differences between the two groups. Further research is needed to better characterize HEMS' ideal role in the response to OHCA as new prehospital resuscitative techniques for non-traumatic and traumatic cardiac arrest are developed.

Natural Experiment Outcomes Studies in Rotor Wing Air Medical Transport: Systematic Review and Meta-Analysis of Before-and-After and Helicopter-Unavailable Publications From 1970 to 2022.

OBJECTIVE: Helicopter emergency medical services (HEMS) is widely used for prehospital and interfacility transport, but there is a paucity of HEMS outcomes data from studies using randomized controlled trial designs. In the absence of robust randomized controlled trial evidence, judgments regarding HEMS potential benefit must be informed by observational data. Within the study design set of observational analyses, the natural experiment (NE) is notable for its high potential methodologic quality; NE designs are occasionally denoted "quasi-experimental." The aim of this study is to examine all NE outcomes studies in the HEMS literature and to discern what lessons can be learned from these potentially high-quality observational data. METHODS: HEMS NE studies were identified during the development of a new HEMS Outcomes Assessment Research Database (HOARD). HOARD was constructed using a broad-ranging search of published and gray literature resources (eg, PubMed, Embase, and Google Scholar) that used variations of the terms "helicopter EMS," "air ambulance," and "air medical transport." Among the 221 studies ultimately included in HOARD, 16 NE publications describing 13 sets of observational data comprising myriad diagnostic groups were identified. Of these 16 HEMS NEs, 4 HEMS NE studies assessing trauma outcomes were used in a meta-analysis. A meta-analysis was also performed of 4 HEMS NE studies. RESULTS: Although the disparity of studies (in terms of both case mix and end points) precluded the generation of a pooled effect estimate of an adjusted mortality benefit of HEMs versus ground emergency medical services, HEMS was found to be associated with outcomes improvement in 8 of the 13 cohorts. CONCLUSION: The weight of the NE evidence supports a conclusion of some form of HEMS-mediated outcomes improvement in a variety of patient types. Meta-analysis of 4 HEMS NE studies assessing trauma outcomes generated a model with acceptable heterogeneity (I2 = 43%, Q test: P = .16), which significantly (P < .01) favored HEMS use with a pooled HEMS survival odd ratio estimate of 1.66 (95% confidence interval, 1.23-2.22).

TeleEMS: An EMS Telemedicine Pilot Program Barriers to Implementation.

INTRODUCTION: In response to the COVID-19 pandemic, emergency medical services (EMS) and hospitals recognized the need for innovative programs addressing 9-1-1 utilization and ambulance transport to provide patient-centered, safe, cost-effective care. The ET3 (Emergency Triage, Treatment, and Transport) model provides flexibility and new payments to ambulance care teams for Medicare beneficiaries for alternate strategies of care. This includes providing treatment in place through telehealth after a 9-1-1 call and ambulance response. Our objective is to evaluate the implementation barriers of a telemedicine service to 9-1-1 responding ambulances providing treatment in place for low-acuity conditions. METHODS: The TeleEMS program was piloted in a large, urban fire-based EMS system with eight ambulances geographically surrounding one hospital. Paramedics received training on the telemedicine software and screening criteria, which were age 1-70 and vital sign parameters. Pregnant, combative, and patients with no clear need for emergency department transport were excluded. Three emergency physicians with additional training in EMS provided the TeleEMS service from 8am to 6 pm on Monday - Friday. The telemedicine software was application-based and provided HIPAA-compliant two-way, real-time audio and video communication through the 4G network on a tablet. The TeleEMS physicians had access to a database of clinics and hospitals that coordinate health care. The TeleEMS physician contacted the patient within 24-72 hours after the encounter for follow-up. RESULTS: The TeleEMS pilot program ran for 12 weeks from April - June 2021. During this time, there were seven completed consults with treatment in place, one completed consult with transport to an emergency department, and five consult attempts that failed due to technological issues with resultant transport. Each of the consults (13/13) met the TeleEMS screening criteria. Post-pilot focus group sessions were held to determine paramedic feedback. Barriers to an EMS telemedicine program include paramedic buy-in, patient expectations for emergency care, technology limitations, and qualified physician resources. CONCLUSIONS: An EMS telemedicine program can be successfully implemented in urban fire-based EMS systems for 9-1-1 responding ambulances. Barriers to implementation should be addressed at the paramedic, patient, technology, and program levels to improve success.

Helicopter Emergency Medical Services Outcomes Research 1983 to 2022: Evidence Overview and Longitudinal Trends.

OBJECTIVE: Helicopter emergency medical services (HEMS) literature has been assessed in reviews focusing on various diagnoses, but there are few, if any, summaries of the entire body of HEMS outcomes evidence. Our goal was to summarize the existing research addressing patient-centered outcomes potentially accrued with HEMS. METHODS: As part of the Critical Care Transport Collaborative Outcomes Research Effort, we generated the HEMS Outcomes Assessment Research Database and executed descriptive analyses of longitudinal trends from 1983 to 2022. Both indexed and gray literature sources were incorporated in the HEMS Outcomes Assessment Research Database. Studies were reviewed by at least 2 authors to select those that addressed a patient-centered outcome. Studies addressing solely HEMS logistics were excluded. Categoric analyses were executed with the Fisher exact test, and continuous variables were evaluated for normality with normal quantile plotting and a comparison of medians and 95% confidence intervals. RESULTS: We found that HEMS outcomes study sample sizes increased steadily from 1983 to 2012, with the most recent decade demonstrating a marked increase in the rate of publication of HEMS outcomes studies. Most research (70.6%) addressed trauma patient outcomes, but recent decades have seen a significant increase in non-trauma studies. Recent decades have also been characterized by an increase in the production of HEMS outcomes research outside of North America and Europe. CONCLUSION: This study summarizes the current state of the HEMS outcome literature. We highlight increasing contributions from worldwide researchers and increasing focus on HEMS benefits in non-trauma cases, particularly time-critical cases such as cardiac or stroke diagnoses. This provides a basis for further investigations into patient-oriented benefits potentially accrued with HEMS.

Changes in alpha, theta, and gamma oscillations in distinct cortical areas are associated with altered acute pain responses in chronic low back pain patients.

Introduction: Chronic pain negatively impacts a range of sensory and affective behaviors. Previous studies have shown that the presence of chronic pain not only causes hypersensitivity at the site of injury but may also be associated with pain-aversive experiences at anatomically unrelated sites. While animal studies have indicated that the cingulate and prefrontal cortices are involved in this generalized hyperalgesia, the mechanisms distinguishing increased sensitivity at the site of injury from a generalized site-nonspecific enhancement in the aversive response to nociceptive inputs are not well known. Methods: We compared measured pain responses to peripheral mechanical stimuli applied to a site of chronic pain and at a pain-free site in participants suffering from chronic lower back pain (n = 15) versus pain-free control participants (n = 15) by analyzing behavioral and electroencephalographic (EEG) data. Results: As expected, participants with chronic pain endorsed enhanced pain with mechanical stimuli in both back and hand. We further analyzed electroencephalographic (EEG) recordings during these evoked pain episodes. Brain oscillations in theta and alpha bands in the medial orbitofrontal cortex (mOFC) were associated with localized hypersensitivity, while increased gamma oscillations in the anterior cingulate cortex (ACC) and increased theta oscillations in the dorsolateral prefrontal cortex (dlPFC) were associated with generalized hyperalgesia. Discussion: These findings indicate that chronic pain may disrupt multiple cortical circuits to impact nociceptive processing.

Frequency of Mass Casualty Incidents (MCIs) Responded to by Helicopter Emergency Medical Services (HEMS).

OBJECTIVE: Mass casualty incidents (MCIs) challenge out-of-hospital and in-hospital personnel as well as impose significant pressure on available resources. Helicopter emergency medical services (HEMS) crews may be involved in the response to an MCI. Thus, there is epidemiological interest to understand the frequency of MCIs responded to by HEMS. METHODS: We used a nationally representative database of emergency medical services activations in the United States (National Emergency Medical Services Information System). We queried 911-initiated (scene) activations during the years 2021 and 2022 within the database and paid special attention to activations defined by crews as MCIs. From this, we were able to calculate the frequency at which HEMS crews responded to MCIs relative to the total number of HEMS scene activations. RESULTS: Of a total of 177,509 HEMS scene activations, less than 1% involved MCIs (0.27%, 486/177,509). Nationally, HEMS crews responded to roughly 2.74 MCIs per 1,000 activations. Variation in MCI frequency was noted across the day of the week, the month of the year, and the time of the day. CONCLUSION: HEMS crews do respond to MCIs although infrequently. Certain time periods are associated with a greater frequency of MCIs. These data will hopefully be able to inform preparedness and training.

Survivorship With Incrementally Faster Times to Primary Percutaneous Coronary Intervention (SWIFT-PPCI): A Systematic Review and Meta-Analysis.

In the United States, there are approximately 750,000 ST-elevation myocardial infarction cases each year. Streamlined care and rapid delivery for primary percutaneous coronary intervention (PPCI) is associated with improved survival. This systematic review and meta-analysis aimed to generate a practical estimate of mortality savings for every notional 30-minute decrease in the time to achieving PPCI. Included studies were those that provided a specific absolute risk reduction for a specific reduction in pre-PPCI time. The eligible studies evaluated the survival benefit from pre-PPCI time savings measured in any interval ending with PPCI and commencing with objectively recorded timing, such as initial emergency call, first medical contact, or hospital arrival. Study planning called for the reporting of data as individual study results, with a pooled effect estimate of relative risk calculated with random-effects meta-analysis. A total of 1,088 records were eligible for review; 52 were reviewed in full text, with 4 studies (total patient n = 235,814, overall mortality 4.7% to 7.8%) included in the final analysis. All 4 studies reported significant time-related survival benefit over the study focus window of 60 to 180 minutes pre-PPCI. The number of lives saved per 100 cases for each 30-minute pre-PPCI time savings ranged from 0.8 to 1.9. The overall effect estimate generated was 0.753 (95% confidence interval 0.712 to 0.796), with acceptable heterogeneity (I2 = 36%). In conclusion, a pooled effect calculation estimated a 24.7% relative risk reduction for each 30 minutes of time savings. For cases that underwent PPCI within 60 to 180 minutes of initial presentation with known baseline mortality risk, the time savings in 30-minute epochs can be leveraged to estimate a specific number of lives saved; this may be useful for those involved in the organization of medical care who make systemwide plans and individual patient triage decisions.

Temporal pain processing in the primary somatosensory cortex and anterior cingulate cortex.

Pain is known to have sensory and affective components. The sensory pain component is encoded by neurons in the primary somatosensory cortex (S1), whereas the emotional or affective pain experience is in large part processed by neural activities in the anterior cingulate cortex (ACC). The timing of how a mechanical or thermal noxious stimulus triggers activation of peripheral pain fibers is well-known. However, the temporal processing of nociceptive inputs in the cortex remains little studied. Here, we took two approaches to examine how nociceptive inputs are processed by the S1 and ACC. We simultaneously recorded local field potentials in both regions, during the application of a brain-computer interface (BCI). First, we compared event related potentials in the S1 and ACC. Next, we used an algorithmic pain decoder enabled by machine-learning to detect the onset of pain which was used during the implementation of the BCI to automatically treat pain. We found that whereas mechanical pain triggered neural activity changes first in the S1, the S1 and ACC processed thermal pain with a reasonably similar time course. These results indicate that the temporal processing of nociceptive information in different regions of the cortex is likely important for the overall pain experience.

Closed-loop stimulation using a multiregion brain-machine interface has analgesic effects in rodents.

Effective treatments for chronic pain remain limited. Conceptually, a closed-loop neural interface combining sensory signal detection with therapeutic delivery could produce timely and effective pain relief. Such systems are challenging to develop because of difficulties in accurate pain detection and ultrafast analgesic delivery. Pain has sensory and affective components, encoded in large part by neural activities in the primary somatosensory cortex (S1) and anterior cingulate cortex (ACC), respectively. Meanwhile, studies show that stimulation of the prefrontal cortex (PFC) produces descending pain control. Here, we designed and tested a brain-machine interface (BMI) combining an automated pain detection arm, based on simultaneously recorded local field potential (LFP) signals from the S1 and ACC, with a treatment arm, based on optogenetic activation or electrical deep brain stimulation (DBS) of the PFC in freely behaving rats. Our multiregion neural interface accurately detected and treated acute evoked pain and chronic pain. This neural interface is activated rapidly, and its efficacy remained stable over time. Given the clinical feasibility of LFP recordings and DBS, our findings suggest that BMI is a promising approach for pain treatment.

Reference Values for Central Airway Dimensions on CT Images of Children and Adolescents.

OBJECTIVE: The purpose of this study was to acquire normative data on central airway dimensions on chest CT scans in the pediatric population. MATERIALS AND METHODS: Chest CT findings reported as normal by a radiologist were collected retrospectively at 10 international centers. An experienced and independent thoracic radiologist reevaluated all CT scans for image quality and for normal findings. Semiautomated image analysis was performed to measure dimensions of the trachea and right and left main bronchi at inspiration. Intrathoracic tracheal length was measured from carina to thorax inlet. Cross-sectional area and short and long axes were measured perpendicular to the longitudinal airway axis starting from the carina every centimeter upward for the trachea and every 0.5 cm downward for the main bronchi. The effects on airway diameters of age, sex, intrathoracic tracheal length, and distance from the carina were investigated by use of mixed-effects models analysis. RESULTS: Among 1160 CT scans collected, 388 were evaluated as normal by the independent radiologist with sufficient image quality and adequate inspiratory volume level. Central airways were successfully semiautomatically analyzed in 294 of 388 CT studies. Age, sex, intrathoracic tracheal length, and distance from carina were all significant predictors in the models for tracheal and right and left main bronchial diameters (p < 0.001). The central airway dimensions increased with age up to 20 years, and dimensions were larger in male than in female adolescents. CONCLUSION: Normative data were determined for the central airways of children and adolescents. Central airway dimensions depended on distance from the carina and on intrathoracic tracheal length.

MRI-based reference range for the renal pelvis anterior-posterior diameter in children ages 0-19 years.

OBJECTIVE: To determine the mean and normal range of anteroposterior diameter (APD) of the renal pelves in children. METHODS: Patients aged 0-19 years with normal spinal MRIs were identified after institutional review board approval. Those with dilating uropathy or abdominal surgery/radiation were excluded. The maximum APD was measured. A mixed linear model was fit to determine the relationship between APD and age, adjusted for bladder distention. The left and right kidneys were treated independently. RESULTS: 283 left and 285 right renal units were included. For the left, a 3.5% increase in APD per year was predicted (p < 0.0001), with the average APD for infants and 18-year olds with non-distended bladders being 2.5 mm (95th percentile: 7.2 mm) and 4.6 mm (13.4 mm), respectively. For the right, a 3.9% increase in APD per year was predicted (p < 0.0001), with the average APD for infants and 18-year olds with non-distended bladders being 2.8 mm (8.4 mm) and 5.5 mm (16.6 mm), respectively. Compared with a non-distended bladder, a distended bladder increased the predicted APD between 23% (right) and 38% (left) (p = 0.01 and p < 0.0001, respectively). CONCLUSION: The mean and normal ranges of APD measured by MRI in children are provided. APD increases with age and bladder distension and is greater on the left. Advances in knowledge: This article establishes normative ranges for APD, a critical component of genitourinary tract evaluation, and does so using the most precise imaging modality for this condition.