Massive Sodium Nitrite Overdose: A Case for Prehospital Methylene Blue.

Sodium nitrite overdose leads to profound methemoglobinemia and may quickly progress to death. It is an increasingly common method of suicide and is often fatal. Methylene blue is an effective but time-sensitive antidote that has the potential to save lives when administered early. In this case report, we describe a fatal sodium nitrite overdose and the subsequent creation of a prehospital protocol for our large urban Emergency Medical Services system.

Implementation of Extracorporeal CPR Programs for Out-of-Hospital Cardiac Arrest: Another Tale of Two County Hospitals.

Extracorporeal cardiopulmonary resuscitation (ECPR) is a form of intensive life support that has seen increasing use globally to improve outcomes for patients who experience out-of-hospital cardiac arrest (OHCA). Hospitals with advanced critical care capabilities may be interested in launching an ECPR program to offer this support to the patients they serve; however, to do so, they must first consider the significant investment of resources necessary to start and sustain the program. The existing literature describes many single-center ECPR programs and often focuses on inpatient care and patient outcomes in hospitals with cardiac surgery capabilities. However, building a successful ECPR program and using this technology to support an individual patient experiencing refractory cardiac arrest secondary to a shockable rhythm depends on efficient out-of-hospital and emergency department (ED) management. This article describes the process of implementing 2 intensivist-led ECPR programs with limited cardiac surgery capability. We focus on emergency medical services and ED clinician roles in identifying patients, mobilizing resources, initiation and management of veno-arterial extracorporeal membrane oxygenation (VA-ECMO) in the ED, and ongoing efforts to improve ECPR program quality. Each center experienced a significant learning curve to reach goals of arrest-to-flow times of cannulation for ECPR. Building consensus from multidisciplinary stakeholders, including out-of-hospital stakeholders; establishing shared expectations of ECPR outcomes; and ensuring adequate resource support for ECPR activation were all key lessons in improving our ECPR programs.

A Practical Solution for Preoxygenation in the Prehospital Setting: A Nonrebreather Mask with Flush Rate Oxygen.

OBJECTIVE: Prehospital clinicians need a practical means of providing adequate preoxygenation prior to intubation. A bag-valve-mask (BVM) can be used for preoxygenation in perfect conditions but is likely to fail in emergency settings. For this reason, many airway experts have moved away from using BVM for preoxygenation and instead suggest using a nonrebreather (NRB) mask with flush rate oxygen.Literature on preoxygenation has suggested that a NRB mask delivering flush rate oxygen (on a 15 L/min O2 regulator, maximum flow, ∼50 L/min) is noninferior to BVM at 15 L/min held with a tight seal. However, in the prehospital setting, where emergency airway management success varies, preoxygenation techniques have not been deeply explored. Our study seeks to determine whether preoxygenation can be optimally performed with NRB at flush rate oxygen. METHODS: We performed a crossover trial using healthy volunteers. Subjects underwent 3-min trials of preoxygenation with NRB mask at 25 L/min oxygen delivered from a portable tank, NRB at flush rate oxygen from a portable tank, NRB with flush rate oxygen from an onboard ambulance tank, and BVM with flush rate oxygen from an onboard ambulance tank. The primary outcome was the fraction of expired oxygen (FeO2). We compared the FeO2 of the BVM-flush to other study groups, using a noninferiority margin of 10%. RESULTS: We enrolled 30 subjects. Mean FeO2 values for NRB-25, NRB-flush ambulance, NRB-flush portable, and BVM-flush were 63% (95% confidence interval [CI] 58-68%), 74% (95%, CI 70-78%), 78% (95%, CI 74-83%), and 80% (95%, CI 75-84%), respectively. FeO2 values for NRB-flush on both portable tank and ambulance oxygen were noninferior to BVM-flush on the ambulance oxygen system (FeO2 differences of 1%, 95% CI -3% to 6%; and 6%, 95% CI 1-10%). FeO2 for the NRB-25 group was inferior to BVM-flush (FeO2 difference 16%, 95% CI 12-21%). CONCLUSIONS: Among healthy volunteers, flush rate preoxygenation using NRB masks is noninferior to BVM using either a portable oxygen tank or ambulance oxygen. This is significant because preoxygenation using NRB masks with flush rate oxygen presents a simpler alternative to the use of BVMs. Preoxygenation using NRB masks at 25 L/min from a portable tank is inferior to BVM at flush rate.

Implementation of Extracorporeal Membrane Oxygenation Without On-Site Cardiac Surgery or Perfusion Support: A Tale of Two County Hospitals.

Patients with refractory respiratory and cardiac failure may present to noncardiac surgery centers. Prior studies have demonstrated that acute care surgeons, intensivists, and emergency medicine physicians can safely cannulate and manage patients receiving extracorporeal membrane oxygenation (ECMO). Harborview Medical Center (Harborview) and Hennepin County Medical Center (Hennepin) are both urban, county-owned, level 1 trauma centers that implemented ECMO without direct, on-site cardiac surgery or perfusion support. Both centers 1) use an ECMO specialist model staffed by specially trained nurses and respiratory therapists and 2) developed comparable training curricula for ECMO specialists, intensivists, surgeons, and trainees. Each program began with venovenous ECMO to provide support for refractory hypoxemic respiratory failure and subsequently expanded to venoarterial ECMO support. The coronavirus disease 2019 (COVID-19) pandemic created an impetus for restructuring, with each program creating a consulting service to facilitate ECMO delivery across multiple intensive care units (ICUs) and to promote fellow and resident training and experience. Both Harborview and Hennepin, urban county hospitals 1,700 miles apart in the United States, independently implemented and operate adult ECMO programs without involvement from cardiovascular surgery or perfusion services. This experience further supports the role of ECMO specialists in the delivery of extracorporeal life support.

Prehospital Ultrasound Diagnosis of Massive Pulmonary Embolism by Non-Physicians: A Case Series.

Massive pulmonary embolism (hemodynamically unstable, defined as systolic BP <90 mmHg) has significant morbidity and mortality. Point of care ultrasound (POCUS) has allowed clinicians to detect evidence of massive pulmonary embolism much earlier in the patient's clinical course, especially when patient instability precludes computerized tomography confirmation. POCUS detection of massive pulmonary embolism has traditionally been performed by physicians. This case series demonstrates four cases of massive pulmonary embolism diagnosed with POCUS performed by non-physician prehospital personnel.

Extracorporeal membrane oxygenation versus conventional rewarming for severe hypothermia in an urban emergency department.

BACKGROUND: Severe hypothermia (core body temperature < 28°C) is life-threatening and predisposes to cardiac arrest. The comparative effectiveness of different active internal rewarming methods in an urban U.S. population is unknown. We aim to compare outcomes between hypothermic emergency department (ED) patients rewarmed conventionally using an intravascular rewarming catheter or warm fluid lavage versus those rewarmed using extracorporeal membrane oxygenation (ECMO). METHODS: We performed a retrospective cohort analysis of adults with severe hypothermia due to outdoor exposure presenting to an urban ED in Minnesota, 2007-2021. The primary outcome was hospital survival. We also calculated the rewarming rate in the 4 h after ED arrival and compared these data between patients rewarmed with ECMO (the extracorporeal rewarming group) versus without ECMO (the conventional rewarming group). We repeated these analyses in the subgroup of patients with cardiac arrest. RESULTS: We analyzed 44 hypothermic ED patients: 25 patients in the extracorporeal rewarming group (median temperature 24.1°C, 84% with cardiac arrest) and 19 patients in the conventional rewarming group (median temperature 26.3°C, 37% with cardiac arrest; 89% received an intravascular rewarming catheter). The median rewarming rate was greater in the extracorporeal versus conventional group (2.3°C/h vs. 1.5°C/h, absolute difference 0.8°C/h, 95% confidence interval [CI] 0.3-1.2°C/h) yet hospital survival was similar (68% vs. 74%). Among patients with cardiac arrest, hospital survival was greater in the extracorporeal versus conventional group (71% vs. 29%, absolute difference 42%, 95% CI 4%-82%). CONCLUSIONS: Among ED patients with severe hypothermia and cardiac arrest, survival was significantly higher with ECMO versus conventional rewarming. Among all hypothermic patients, ECMO use was associated with faster rewarming than conventional methods.

Prehospital Pericardiocentesis Using a Pneumothorax Needle.

Case: We discuss a patient with a penetrating knife wound to the chest who lost pulses from cardiac tamponade. Prehospital ultrasound was able to quickly identify the tamponade and a pericardiocentesis was performed using a Simplified Pneumothorax Emergency Air Release (SPEARTM) Needle (North American Rescue, LLC, USA) with subsequent return of spontaneous circulation. Discussion: Penetrating chest trauma carries significant morbidity and mortality. In traumatic cardiac arrest due to a penetrating mechanism, it is paramount that the patient be transported to a trauma center as quickly as possible. Prehospital pericardiocentesis is a potential life-saving intervention.

The Hennepin Ketamine Study Investigators' Reply.

We read with interest the recent editorial, "The Hennepin Ketamine Study," by Dr. Samuel Stratton commenting on the research ethics, methodology, and the current public controversy surrounding this study.1 As researchers and investigators of this study, we strongly agree that prospective clinical research in the prehospital environment is necessary to advance the science of Emergency Medical Services (EMS) and emergency medicine. We also agree that accomplishing this is challenging as the prehospital environment often encounters patient populations who cannot provide meaningful informed consent due to their emergent conditions. To ensure that fellow emergency medicine researchers understand the facts of our work so they may plan future studies, and to address some of the questions and concerns in Dr. Stratton's editorial, the lay press, and in social media,2 we would like to call attention to some inaccuracies in Dr. Stratton's editorial, and to the lay media stories on which it appears to be based.Ho JD, Cole JB, Klein LR, Olives TD, Driver BE, Moore JC, Nystrom PC, Arens AM, Simpson NS, Hick JL, Chavez RA, Lynch WL, Miner JR. The Hennepin Ketamine Study investigators' reply. Prehosp Disaster Med. 2019;34(2):111-113.

Emergency Department Management of Out-of-Hospital Laryngeal Tubes.

STUDY OBJECTIVE: Laryngeal tubes are commonly used by emergency medical services (EMS) personnel for out-of-hospital advanced airway management. The emergency department (ED) management of EMS-placed laryngeal tubes is unknown. We seek to describe ED airway management techniques, success, and complications of patients receiving EMS laryngeal tubes. METHODS: Using a keyword text search of ED notes, we identified patients who arrived at our ED with a laryngeal tube from 2010 through 2017. We performed structured chart and video reviews for all eligible patients. In our ED, emergency physicians perform all airway management, and there is no protocol dictating airway management for patients arriving with a laryngeal tube. Using descriptive methods, we report the techniques, success, and complications of ED airway management. RESULTS: We analyzed data on 647 patients receiving out-of-hospital laryngeal tubes, including 472 (73%) with cardiac arrest from medical causes, 75 (21%) with cardiac arrest from trauma, and 100 (15%) with other conditions. For 580 patients (89%), emergency physicians exchanged the laryngeal tube for a definitive airway in the ED. Of the 67 patients not intubated in the ED, 66 died in the ED without further airway management. Of the 580 patients intubated in the ED, orotracheal intubation was the first method attempted for 578 (>99%) and was successful on the first attempt for 515 of 578 (89%). Macintosh video laryngoscopy (88% of initial attempts) and a bougie (68% of initial attempts) were commonly used adjuncts. For 345 of 578 patients (60%), the laryngeal tube was removed before intubation attempts. For 112 of 578 patients (19%), the first intubation attempt occurred with the deflated laryngeal tube left in place. Three patients (<1%) required a surgical airway. CONCLUSION: In this cohort, emergency physicians successfully exchanged an out-of-hospital laryngeal tube for an endotracheal tube, using commonly available airway management techniques. ED clinicians should be familiar with techniques for exchanging out-of-hospital extraglottic airways for an endotracheal tube.

EphA4 and ephrin-B2 expression patterns during inferior colliculus projection shaping prior to experience.

Central processing of complex auditory tasks requires elaborate circuitry. The auditory midbrain, or inferior colliculus (IC), epitomizes such precise organization, where converging inputs form discrete, tonotopically-arranged axonal layers. Previously in rat, we established that shaping of multiple afferent patterns in the IC central nucleus (CNIC) occurs prior to experience. This study implicates an Eph receptor tyrosine kinase and a corresponding ephrin ligand in signaling this early topographic registry. We report that EphA4 and ephrin-B2 expression patterns in the neonatal rat and mouse IC correlate temporally and spatially with that of developing axonal layers. DiI-labeling confirms projections arising from the lateral superior olive (LSO) form frequency-specific layers within the ipsilateral and contralateral mouse CNIC, as has been described in other species. Immunohistochemistry (EphA4 and ephrin-B2) and ephrin-B2 lacZ histochemistry reveal clear gradients in expression across the tonotopic axis, with most concentrated labeling observed in high-frequency, ventromedial aspects of the CNIC. Discrete patches of labeling were also discernible in the external cortex of the IC (ECIC; EphA4 patches in rat, ephrin-B2 patches in mouse). Observed gradients in the CNIC and compartmentalized ECIC expression persisted through the first postnatal week, before becoming less intense and more homogeneously distributed by the functional onset of hearing. EphA4 and ephrin-B2-positive neurons were evident in several auditory brainstem nuclei known to send patterened inputs to the IC. These findings suggest the involvement of cell-cell EphA4 and ephrin-B2 signaling in establishing order in the developing IC.