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.

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.

Feasibility and Safety of Oral Risperidone to Treat Prehospital Agitation.

OBJECTIVE: Agitation is a common prehospital problem and frequently presents without a clear etiology. Given the dynamic environment of the prehospital setting, there has historically been a varied approach to treating agitation with a heavy reliance on parenteral medications. Newer best practice guidelines recommend the incorporation of oral medications to treat patients experiencing agitation. Therefore, we evaluated the use of oral risperidone in a single system after a change in protocol occurred. METHODS: This was conducted as a retrospective chart review of an urban/suburban Emergency Medical Services system over the period of 8 months. The first day this medication was implemented throughout the service was included. Charts were included for selection if they included risperidone oral dissolving tablet (ODT) as a charted medication. The primary outcome was administration of additional medications to treat agitation. Exploratory outcome measures included acceptance of medication, documented injury to paramedics, documented injuries to patients, scene times, and adverse events that could possibly be linked to the medication. RESULTS: A total of 552 records were screened for inclusion. Risperidone was offered to 530 patients and accepted by 512 (96.6%). Of these 512 patients, the median age of included patients was 39 years old (IQR 29-52 years old) with a range of 18-89 years old. Rescue or additional medications for agitation were required in 9 (1.8%) cases. There were a total of 4 (0.8%) potential complications following administration of risperidone. There were no reported assaults with subsequent injuries to prehospital personnel or injuries sustained by patients reported in this study. CONCLUSIONS: Risperidone ODT was found to be a safe and effective medication to treat mild agitation in a large urban and suburban EMS system. The need for additional medications to treat agitation was rare, and there were no documented injuries to either patients or paramedics.

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.

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 physiologic effects of a new generation conducted electrical weapon on human volunteers at rest.

Axon Enterprise, Inc. (Axon) released its newest generation conducted electrical weapon (CEW), the T7, in October 2018. In order to compare the effects of this new CEW to prior generations, we used our previously described methodology to study the physiologic effects of CEWs on human volunteers at rest. This was a prospective, observational study of human subjects consisting of two parts. Part 1 was testing a single cartridge (2-probe) exposure. Subjects received a 10-s exposure from the T7 to the back with a 30 cm (12 in.) spread between the two probes. Part 2 was testing a simultaneous two-cartridge (4-probe) exposure. Subjects received a 10-s exposure from the T7 to the back with two cartridges with a 10 cm (4 in.) spread between each probe pair. The probe pairs were arranged cephalad to caudal such that the distance between the top probe of the first cartridge and the bottom probe of the second cartridge was 30 cm (12 in.). Vital signs were measured immediately before and after the exposure. Continuous spirometry was performed. ECG monitoring was performed immediately before and after the exposure. Venous pH, lactate, potassium, CK, catecholamines, and troponin were measured before and immediately after the exposure, at 1-h post-exposure, and again at 24 h. 11 subjects completed part 1 of the study. 9 subjects completed part 2 of the study. No subjects had a dysrhythmia or morphology change in the surface ECG. There were no statistical changes in vital signs pre- and post-exposure. While subjects did not have a statistical change in spirometry parameters pre-exposure to exposure except for a small drop in PETCO2, there was an increase in minute ventilation after the exposure that could have several explanations. A similar pattern was seen with prior generation weapons. No subject had elevated troponin levels. Other blood parameters including venous pH, lactate, potassium, CK, and catecholamines had changes similar to prior generation weapons. Comparison of the data for the single-cartridge exposures against the simultaneous two-cartridge exposures yielded no difference in vital signs, but the minute ventilation was higher for the two-cartridge exposures. The blood data, where there was a difference, was mixed. In our study, the physiologic effects of the Axon T7 are modest, consistent with the electrically-induced motor nerve-driven muscle contraction, and were similar to prior generation weapons.