A pilot evaluation of respiratory mechanics during prehospital manual ventilation.

INTRODUCTION: Respiratory mechanics, such as tidal volume (VT) and inspiratory pressures, may affect outcome in hospitalized patients with respiratory failure. Little is known about respiratory mechanics in the prehospital setting. METHODS: In this prospective, pilot investigation of patients receiving prehospital advanced airway placement, paramedics applied a device to measure respiratory mechanics. We evaluated tidal volume (VT) per predicted body weight (VTPBW) to determine the proportion of breaths within the lung-protective range of 4-10 mL/kg per PBW overall, according to ventilation bag volume (large versus small) and cardiac arrest status (active CPR, post-ROSC, non-arrest). RESULTS: Over 16-months, 7371 post-intubation breaths were measured in 54 patients, 32 patients with cardiac arrest and 22 with other conditions. Paramedics ventilated 19 patients with a small bag and 35 patients with a large bag. Overall, mean VT was 435 mL (95% CI 403, 467); VTPBW was 7.0 mL/kg (95% CI 6.4, 7.6) with 75% within the lung-protective range. Mean VTPBW and peak pressure differed according to arrest status (absolute difference -0.36 mL/kg and 32 cmH2O for active CPR compared to post-ROSC), though not according to bag size. CONCLUSIONS: We observed that measuring respiratory mechanics in the prehospital setting was feasible. Tidal volumes were generally delivered within a safe range. Respiratory mechanics varied most significantly with active CPR with lower VTPBW and higher peak pressures, though did not seem to be affected by bag size. Future work might examine the relationship between respiratory mechanics and outcomes, which may identify opportunities to improve clinical outcomes.

Prehospital tourniquet use: An evaluation of community application and outcome.

BACKGROUND: There is substantial investment in layperson and first responder training involving tourniquet use for hemorrhage control. Little is known however about prehospital tourniquet application, field conversion, or outcomes in the civilian setting. We describe the experience of a metropolitan region with prehospital tourniquet application. METHODS: We conducted a retrospective cohort study characterizing prehospital tourniquet use treated by emergency medical services (EMS) in King County, Washington, from January 2018 to June 2019. Emergency medical services and hospital records were abstracted for demographics, injury mechanism, tourniquet details, clinical care, and outcomes. We evaluated the incidence of tourniquet application, who applied the device (EMS, law enforcement, or layperson), and subsequent course. RESULTS: A total of 168 patients received tourniquet application, an incidence of 5.1 per 100,000 person-years and 3.48 per 1,000 EMS responses for trauma. Tourniquets were applied for penetrating trauma (64%), blunt trauma (30%), and bleeding ateriovenous fistulas (7%). A subset was critically ill: 13% had systolic blood pressures of <90 mm Hg, 8% had Glasgow Coma Scale score of <13, and 3% had cardiac arrest. Among initial applications, 48% were placed by law enforcement, 33% by laypersons, and 18% by EMS. Among tourniquets applied by layperson or law enforcement (n = 137), EMS relied solely on the original tourniquet in 45% (n = 61), placed a second tourniquet in 20% (n = 28), and removed the tourniquet without replacement in 35% (n = 48). Overall, 24% required massive transfusion, 59% underwent urgent surgery, and 21% required vascular surgery. Mortality was 3% (n = 4). At hospital discharge, the tourniquet limb was fully functional in 81%, partially functional in 10%, and nonfunctional in 9%; decreased function was not attributed to tourniquet application. CONCLUSION: The high rate of application, need for urgent hospital intervention in a subset, and low incidence of apparent complication suggest that efforts to increase access and early tourniquet use can provide public health benefit. LEVEL OF EVIDENCE: Therapeutic, level IV.