The use of ultrasound in the out-of-hospital environment is increasingly feasible. The potential uses for point-of-care ultrasound (POCUS) by paramedics are many, but have historically been limited to traumatic indications. This study utilized a scoping review methodology to map the evidence for the use of POCUS by paramedics to assess respiratory distress and to gain a broader understanding of the topic.

Databases Ovid MEDLINE, EMBASE, CINAHL Plus, and PUBMED were searched from January 1, 1990 through April 14, 2021. Google Scholar was searched, and reference lists of relevant papers were examined to identify additional studies. Articles were included if they reported on out-of-hospital POCUS performed by non-physicians for non-traumatic respiratory distress.

A total of 591 unique articles were identified, of which seven articles met the inclusion criteria. The articles reported various different scan protocols and, with one exception, suffered from low enrolments and low participation. Most articles reported that non-physician-performed ultrasound was feasible. Articles reported moderate to high levels of agreement between paramedics and expert reviewers for scan interpretation in most studies.

Paramedics and emergency medical technicians (EMTs) have demonstrated the feasibility of lung ultrasound in the out-of-hospital environment. Further research should investigate the utility of standardized education and scanning protocols in paramedic-performed lung ultrasound for the differentiation of respiratory distress and the implications for patient outcomes.

A feedforward pathological signaling loop generated by TNFα and IFN-γ synergy in the inflamed lung, driving CXCL-10 (IP-10) and CXCL-9 chemokine-mediated activated T-cell and monocyte/macrophage tissue recruitment, may define the inflammatory biology of lethal COVID-19 respiratory failure.

To assess TNFα-antagonist therapy, 18 hospitalized adults with hypoxic respiratory failure and COVID-19 pneumonia received single-dose infliximab-abda therapy 5 mg/kg intravenously between April and December 2020. The primary endpoint was time to increase in oxygen saturation to fraction of inspired oxygen ratio (SpO2/FiO2) by ≥50 compared to baseline and sustained for 48 h. Secondary endpoints included 28-day mortality, dynamic cytokine profiles, secondary infections, duration of supplemental oxygen support, and hospitalization.

Patients were predominantly in critical respiratory failure (15/18, 83%), male (14/18, 78%), above 60 years (median 63 years, range 31–80), race-ethnic minorities (13/18, 72%), lymphopenic (13/18, 72%), steroid-treated (17/18, 94%), with a median ferritin of 1953 ng/ml. Sixteen patients (89%) met the primary endpoint within a median of 4 days; 14/18 (78%) were discharged in a median of 8 days and were alive at 28-day follow-up. Three deaths were attributed to secondary lung infection. Mean plasma IP-10 levels declined sharply from 9183 to 483 pg/ml at Day 3 and 146 pg/ml at Day 14/discharge. Significant Day 3 declines in IFN- $\gamma $ , TNFα, IL-27, CRP, and ferritin occurred. IP-10 and CXCL-9 declines were strongly correlated among patients with lymphopenia reversal (Day 3, Pearson r: 0.98, P-value 0.0006).

Infliximab-abda may rapidly abrogate pathological inflammatory signaling to facilitate clinical recovery in severe and critical COVID-19.

Patients with respiratory failure are usually mechanically ventilated, mostly with fraction of inspired oxygen (FiO2) > 0.21. Minimizing FiO2 is increasingly an accepted standard. In underserved nations and disasters, salvageable patients requiring mechanical ventilation may outstrip oxygen supplies.

The hypothesis of the present study was that mechanical ventilation with FiO2 = 0.21 is feasible. This assumption was tested in an Acute Respiratory Distress Syndrome (ARDS) model in pigs.

Seventeen pigs were anesthetized, intubated, and mechanically ventilated with FiO2 = 0.4 and Positive End Expiratory Pressure (PEEP) of 5cmH2O. Acute Respiratory Distress Syndrome was induced by intravenous (IV) oleic acid (OA) infusion, and FiO2 was reduced to 0.21 after 45 minutes of stable moderate ARDS. If peripheral capillary oxygen saturation (SpO2) decreased below 80%, PEEP was increased gradually until maximum 20cmH2O, then inspiratory time elevated from one second to 1.4 seconds.

Animals developed moderate ARDS (mean partial pressure of oxygen [PaO2]/FiO2 = 162.8, peak and mean inspiratory pressures doubled, and lung compliance decreased). The SpO2 decreased to <80% rapidly after FiO2 was decreased to 0.21. In 14/17 animals, increasing PEEP sufficed to maintain SpO2 > 80%. Only in 3/17 animals, elevation of FiO2 to 0.25 after PEEP reached 20cmH2O was needed to maintain SpO2 > 80%. Animals remained hemodynamically stable until euthanasia one hour later.

In a pig model of moderate ARDS, mechanical ventilation with room air was feasible in 14/17 animals by elevating PEEP. These results in animal model support the potential feasibility of lowering FiO2 to 0.21 in some ARDS patients. The present study was conceived to address the ethical and practical paradigm of mechanical ventilation in disasters and underserved areas, which assumes that oxygen is mandatory in respiratory failure and is therefore a rate-limiting factor in care capacity allocation. Further studies are needed before paradigm changes are considered.

Non-invasive positive pressure ventilation (NIPPV) is used to treat severe acute respiratory distress. Prehospital NIPPV has been associated with a reduction in both in-hospital mortality and the need for invasive ventilation.

The authors of this study examined factors associated with NIPPV failure and evaluated the impact of NIPPV on scene times in a critical care helicopter Emergency Medical Service (HEMS). Non-invasive positive pressure ventilation failure was defined as the need for airway intervention or alternative means of ventilatory support.

A retrospective chart review of consecutive patients where NIPPV was completed in a critical care HEMS was conducted. Factors associated with NIPPV failure in univariate analyses and from published literature were included in a multivariable, logistic regression model.

From a total of 44 patients, NIPPV failed in 14 (32%); a Glasgow Coma Scale (GCS) <15 at HEMS arrival was associated independently with NIPPV failure (adjusted odds ratio 13.9; 95% CI, 2.4-80.3; P=.003). Mean scene times were significantly longer in patients who failed NIPPV when compared with patients in whom NIPPV was successful (95 minutes vs 51 minutes; 39.4 minutes longer; 95% CI, 16.2-62.5; P=.001).

Patients with a decreased level of consciousness were more likely to fail NIPPV. Furthermore, patients who failed NIPPV had significantly longer scene times. The benefits of NIPPV should be balanced against risks of long scene times by HEMS providers. Knowing risk factors of NIPPV failure could assist HEMS providers to make the safest decision for patients on whether to initiate NIPPV or proceed directly to endotracheal intubation prior to transport.

LeeJS , O’DochartaighD , MacKenzieM , HudsonD , CouperthwaiteS , Villa-RoelC , RoweBH . Factors Associated with Failure of Non-invasive Positive Pressure Ventilation in a Critical Care Helicopter Emergency Medical Service. Prehosp Disaster Med2015; 30(2): 1–5

The objective of this study was to evaluate the rapid training of medical students and their ability to provide effective manual ventilation using the bag-valve-mask technique.

A rapid training session highlighting essential aspects of the correct bag-valve-mask technique was given to 31 medical students.This was followed by a simulated experience with a certified respiratory therapist, monitored according to a checklist of essential bag-valve-mask (BVM) competency requirements. Pretest and post-test surveys assessed the medical students' knowledge and ability to provide adequate BVM technique.

Thirty-one students participated. Presurvey results demonstrated a clear identification of the potential risk for a disaster (pandemic, natural, bioterrorist) with 55% of students responding that a definite risk did exist. Their usefulness in such an event also was ascertained with 55% of students replying they would assist with basic medical tasks, assist doctors, or assist with cardiopulmonary resuscitation. Post-survey results administered after a 30-minute didactic session on the basic features of resuscitation equipment and the essential components of BVM technique demonstrated that a majority of students knew the proper head positioning maneuvers in cases not involving trauma (93%) and in cases involving trauma (72%). All students completed and passed the competency checklist.

Medical students can be rapidly trained and be utilized as a potential resource to carry out the potentially lifesaving task of manual ventilation using the BVM technique in a disaster situation in which the availability of mechanical ventilators and respiratory therapists may be limited.