This study describes the association of ED arrival mode with AHF management in the ED and patient outcomes. Firstly, this study shows that in Europe the majority of AHF patients arrived at the ED by EMS. These patients were more likely to be older females with dementia than the patients self-presenting. Secondly, patients arriving at the ED by EMS suffered more often from respiratory distress, and consequently received more often ventilatory support. However, no other differences were observed in the administration frequencies of AHF treatments in the ED. Thirdly, EMS patients had worse short-term outcomes and the use of EMS was an independent predictor of 30-day mortality.
In the present study, the proportion of AHF patients using EMS is among the highest in the literature 1-7,23. In line with the previous studies, older women were more prone to use EMS 3-5. However, the comorbidities associated with the EMS use differed between these studies. In our study, EMS patients tended to have more dementia and a history of pulmonary embolism compared to non-EMS patients. In a Finnish study, EMS patients had more often cardiovascular disease and chronic kidney disease (CKD) 3, in Spain cardiovascular diseases, CKD, COPD, and dementia were more prevalent 4, and in North America the only more prevalent comorbidity was hypertension 5. Most AHF patients had a history of HF. Contrary to some of the earlier studies no significant difference occurred between EMS and non-EMS patients 3, 5.
Although most initial parameters, such as SpO2, HR or BP, did not differ between the patient groups, EMS patients suffered more often from respiratory distress, had abnormal breath sounds, confusion, higher levels of NT-proBNP, and lower pH, reflecting more severe clinical presentation of AHF, especially pulmonary oedema 24. As also reported earlier 5, the EMS patients had shorter duration of symptoms before ED admission, which may also reflect the more severe clinical presentation.
Respiratory distress is one of the most common reasons for EMS use 25, as also seen in our study. Due to more severe respiratory distress, EMS patients received more often ventilatory support compared to their counterparts. Although, the use of NIV in the EMS group was about the average compared to earlier studies 1, 2, 11, 13, 14, 16, 17, it was fairly low in light of the ESC guidelines 9. Naturally, the use of NIV and supplementary oxygen were associated to higher RR and lower SpO2. However, one fourth of all the AHF patients in our study had SpO2 less than 90 % with supplementary oxygen, suggesting that NIV might have been indicated more often in both patient groups. Yet, 14 % of EMS patients were reported to have confusion, one of the contraindications for NIV use, which could partly explain the relatively low frequency of NIV use. Moreover, one fifth of all the patients reported to have confusion were intubated, which was significantly more often compared to the rest of the AHF patients.
Since the clear majority of AHF patients present with congestion without hypoperfusion and hypotension 9, 10, 26, vasodilators and diuretics are the mainstay of AHF management 9. Although only 5 % of all AHF patients in our study were hypotensive and half hypertensive, only one patient out of eight received nitrate infusion. The underuse of vasodilators has been observed previously as well 10, 11, 15. In contrast, diuretics were given to 70 % of patients. All in all, there is room for improvement in the ED management of AHF as also pointed out earlier 4.
Finally, EMS patients were more often admitted to a ward and, in line with previous studies, had significantly higher in-hospital 4, 7 and 30-day mortality 4, 5, 727. Indeed, EMS patients seemed more fragile and severely ill 3, 4 and the same factors related to EMS use – female gender and confusion– were also observed among the independent predictors of 30-day mortality. Notably, confusion was a strong marker for increased risk of death as well, which warrants our attention to asses mental state not only in the most severe AHF, i.e. cardiogenic shock 28, but in all AHF patients. Still, as also shown earlier 5, 7, 27 EMS use remained an independent predictor of 30-day mortality, which may be linked to patients’ fragility and illness severity affected by unmeasured and unknown confounders, as well to patient preference. All in all, the selection of AHF patients for EMS transportation by dispatch centres and EMS seems reasonable in Europe.
Limitations
Some limitations need to be addressed. First, we didn’t have information about the criteria for EMS referral in different EMS regions. Second, our data did not include chest x-ray findings even though the clinician used imagining in decision making. Yet, the chest x-ray is known to have limited specificity and sensitivity 9, 17. Third, the doses of AHF medications were not registered. Those might have differed between EMS and non-EMS patients due to difference in disease severity, but the overall use of AHF medications was similar. Fourth, there was a fair amount of missing data in some of the variables, especially in biochemistry, warranting caution in the interpretation of the results from the multivariable analyses.