Frequency and severity of prehospital obstetric events encountered by emergency medical services in the United States.

BACKGROUND: Prehospital obstetric events encountered by emergency medical services (EMS) can be high-risk patient presentations for which suboptimal care can cause substantial morbidity and mortality. The frequency of prehospital obstetric events is unclear because existing descriptions have reported obstetric and gynecological conditions together, without delineating specific patient presentations. Our objective was to identify the types, frequency, and acuity of prehospital obstetric events treated by EMS personnel in the US. METHODS: We conducted a cross-sectional analysis of EMS patient care records in the 2018 National EMS Information System dataset (n=22,532,890). We focused on EMS activations (i.e., calls for service) for an emergency scene response for patients aged 12-50 years with evidence of an obstetric event. Type of obstetric event was determined by examining patient symptoms, the treating EMS provider's impression (i.e., field diagnosis), and procedures performed. High patient acuity was ascertained by EMS documentation of patient status and application of the modified early obstetric warning system (MEOWS) criteria, with concordance assessed using Cohen's kappa. Descriptive statistics were calculated to describe the primary symptoms, impressions, and frequency of each type of obstetric event among these activations. RESULTS: A total of 107,771 (0.6%) of EMS emergency activations were identified as involving an obstetric event. The most common presentation was early or threatened labor (15%). Abdominal complaints, including pain and other digestive/abdomen signs and symptoms, was the most common primary symptom (29%) and primary impression (18%). We identified 3,489 (3%) out-of-hospital deliveries, of which 1,504 were preterm. Overall, EMS providers documented 34% of patients as being high acuity, similar to the MEOWS criteria (35%); however, there were high rates of missing data for EMS documented acuity (19%), poor concordance between the two measures (Cohen's kappa=0.12), and acuity differences for specific conditions (e.g., high acuity of non-cephalic presentations, 77% in EMS documentation versus 53% identified by MEOWS). CONCLUSION: Prehospital obstetric events were infrequently encountered by EMS personnel, and about one-third were high acuity. Additional work to understand the epidemiology and clinical care of these patients by EMS would help to optimize prehospital care and outcomes.

Laryngeal Cuff Force Application Modeling During Air Medical Evacuation Simulation.

Endotracheal tubes are intended to protect the airway and assist with mechanical ventilation in sedated patients. The blood vessels of the tracheal mucosa can be compressed by high tracheal tube cuff pressures (> 30 cm H2O), leading to reduced mucosal blood flow with resulting ischemia and morbidity. Previous research showed a direct correlation between aircraft pressure altitude and the pressure reading from the tracheal cuff, with resulting pressures > 80 cm H2O at 10,000 ft. Standard practice is to periodically remove air from the cuff during ascent based on assumed increased pressure on the adjacent tracheal mucosa. Using a vacuum chamber and a direct reading micropressure sensor in a 22-mm-diameter semirigid tube, we assessed the direct force applied by the tracheal cuff against the laryngeal tube analog. Standard tracheal cuffs showed direct force/pressure relationships when properly inflated to 20 cm H2O but much less than reported in the literature. Current literature reports values of 55 to 150 cm H2O at 5,000 ft, whereas we report 23 to 25 cm H2O. Our data indicate that a properly inflated cuff does not exceed the critical pressure of 30 cm H2O until the altitude exceeds 8,000 ft. Thus, the standard practice of deflating the laryngeal cuff on ascent should be reconsidered because it may be counterproductive to patient safety.

Describing Prehospital Deliveries in the State of Michigan.

Introduction We observed clinically that prehospital deliveries locally appeared to have a high rate of complications and appeared associated with midwife deliveries. There is scant literature that addresses prehospital deliveries across a state. We set out to describe utilization, complications, and short-term outcomes of EMS-attended prehospital deliveries in Michigan in 2015, and to describe the relationship between prehospital delivery and socioeconomic status (SES). Methods We identified candidate cases for prehospital deliveries through the Michigan EMS Information System (MI-EMSIS). To assess the relationship of SES with the frequency of EMS delivery, we utilized the mean income of the patient residences' zip codes. Results We identified 223 EMS-attended deliveries from 1.6 million MI-EMSIS records. Most births were normal vaginal deliveries on the scene or en route to the hospital (92, 40.0%) or delivered prior to EMS arrival (58, 25.4%). Maternal or fetal complications were identified in 69 (32.0%) deliveries. We identified a few midwife-attended deliveries (31), but these had a high rate of complications (19, 61.3%). The frequency of prehospital delivery was inversely related to estimated patient income (Pearson=-0.85). Conclusions EMS deliveries were rare and most were normal vaginal deliveries, but almost a third had complications. Midwife and EMS-attended deliveries were rare, but when they occurred, had high rates of complications. Although an imperfect measure of patient SES, frequency of delivery was inversely related to patient income, and agencies that provide care in these communities should have focused training.