Shedding light into the black box of out-of-hospital respiratory distress-A retrospective cohort analysis of discharge diagnoses, prehospital diagnostic accuracy, and predictors of mortality

Abstract

Background: Although respiratory distress is one of the most common complaints of patients requiring emergency medical services (EMS), there is a lack of evidence on important aspects.

Objectives: Our study aims to determine the accuracy of EMS physician diagnostics in the out-of-hospital setting, identify examination findings that correlate with diagnoses, investigate hospital mortality, and identify mortality-associated predictors.

Methods: This retrospective observational study examined EMS encounters between December 2015 and May 2016 in the city of Aachen, Germany, in which an EMS physician was present at the scene. Adult patients were included if the EMS physician initially detected dyspnea, low oxygen saturation, or pathological auscultation findings at the scene (n = 719). The analyses were performed by linking out-of-hospital data to hospital records and using binary logistic regressions.

Results: The overall diagnostic accuracy was 69.9% (485/694). The highest diagnostic accuracies were observed in asthma (15/15; 100%), hypertensive crisis (28/33; 84.4%), and COPD exacerbation (114/138; 82.6%), lowest accuracies were observed in pneumonia (70/142; 49.3%), pulmonary embolism (8/18; 44.4%), and urinary tract infection (14/35; 40%). The overall hospital mortality rate was 13.8% (99/719). The highest hospital mortality rates were seen in pneumonia (44/142; 31%) and urinary tract infection (7/35; 20%). Identified risk factors for hospital mortality were metabolic acidosis in the initial blood gas analysis (odds ratio (OR) 11.84), the diagnosis of pneumonia (OR 3.22) reduced vigilance (OR 2.58), low oxygen saturation (OR 2.23), and increasing age (OR 1.03 by 1 year increase).

Conclusions: Our data highlight the diagnostic uncertainties and high mortality in out-of-hospital emergency patients presenting with respiratory distress. Pneumonia was the most common and most frequently misdiagnosed cause and showed highest hospital mortality. The identified predictors could contribute to an early detection of patients at risk.

Fig 1. Study population considering the inclusion and exclusion criteria.

PEMT physician-staffed emergency medical team.

Fig 2. Frequency of discharge diagnoses and diagnostic accuracy of the PEMT.

PEMT: physician-staffed emergency medical team; COPD: chronic obstructive pulmonary disease; ACS: acute coronary syndrome; NSTE-ACS: non-ST segment elevation ACS; STEMI: ST-elevation myocardial infarction; total of number of discharge diagnoses made: 793.

Fig 3. Which out-of-hospital diagnoses did the PEMTs suspect in cases of misdiagnosis?

Fig 3 shows the incorrect PEMT out-of-hospital diagnoses for the three most frequent discharge diagnoses; PEMT: physician-staffed emergency medical team; COPD: chronic obstructive pulmonary disease.

Fig 4. Associations of initial examination findings and discharge diagnoses.

Binary logistic regression; only significant results are displayed, * mean of the odds ratios (when identical auscultation findings in the out-of-hospital setting and in the emergency department yielded significant results). The following variables were reviewed for associations with discharge diagnoses: out-of-hospital findings: hypotension (systolic blood pressure < 100 mmHg), tachycardia (heart rate > 100/min), low oxygen saturation (peripheral oxygen saturation < 90%), tachypnea (respiratory rate ≥ 22/min), high temperature (body temperature ≥ 38°C), body temperature ≤ 36°C, reduced vigilance (Glasgow Coma Scale < 15), reported pain (numeric rating scale ≥ 1), crackles upon auscultation, wheezing upon auscultation, emergency department findings: crackles upon auscultation, wheezing upon auscultation, silent lung upon auscultation, and lower extremity edema. Detailed results of logistic regressions are shown in S2 Table.

Fig 5. Hospital mortality and misdiagnoses by the PEMT.

Fig 5 presents hospital mortality rates for the most frequent discharge diagnoses as well as the number of out-of-hospital misdiagnosed cases in lethal outcomes. PEMT: physician-staffed emergency medical team; COPD: chronic obstructive pulmonary disease.