Prehospital Triage of Patients With Severe Shortness of Breath Using Biomarkers

Prehospital Triage of Patients With Severe Dyspnea Using Point-of-Care N-terminal Pro-Brain Natriuretic Peptide. PreBNP Trial.

Breathlessness is a dangerous symptom. Preliminary data from national and regional Danish databases show, that patients with shortness of breath in the ambulance have a very high mortality. Breathlessness can be caused by many different conditions - but heart diseases and lung diseases are dominant. The mortality is especially high in patients with breathlessness caused by heart disease.

Distinguishing these different causes of breathlessness is a classical, often difficult, discipline in medicine. Visitation and guidance of treatment in patients with breathlessness in the prehospital setting relies on medical history and physical examination and as a consequence prehospital treatment for breathlessness is often non-specific. The use of heart-failure specific biomarkers may improve prehospital visitation and treatment of patients with breathlessness.

We hypothesize, that

1. Supplementing the routine examination by prehospital anesthesiologist with measurement of a biomarker for heart failure increases the proportion of patients with severe shortness of breath caused by heart disease triaged directly to department of cardiology
2. This strategy does not increase the proportion of patients with severe shortness of breath caused by non-heart disease triaged directly to department of cardiology

Measurement of the biomarker for heart failure N-terminal pro-Brain Natriuretic Peptide (NT-proBNP):

In patients randomized to the strategy with supplementary measurement of NT-proBNP, a blood sample will be drawn from the peripheral venous catheter that is routinely inserted. This will be analyzed point-of-care in the ambulance.

Interpretation of NT-proBNP:

Cut-off values based on bootstrap-validated optimal cut-points for heart failure on will be used.

Confirmatory ('rule in') cut point

< 50 years: 450 pg/mL

50-75 years: 900 pg/mL

> 75 years: 1800 pg/mL

Exclusionary ('rule out') cut point

All patients: 300 pg/mL

The emergency physicians will be thoroughly informed about these cut-points, but told not to triage to department of cardiology or other department strictly according to NT-proBNP, but according to clinical assessment AND NT-proBNP.

Inclusion Criteria:

All patients requiring dispatch of emergency physician because of severe dyspnea.

Severe dyspnea is defined by dyspnea plus at least ONE of the following

• Respiration frequency > 20 or < 8
• Saturation < 96 without supplementary oxygen
• Heart rate > 100 or < 50
• Systolic blood pressure < 100 or > 200
• Difficulty talking
• Central or peripheral cyanosis
• Use of accessory muscles of respiration
• Glasgow coma scale score < 15

AND because of the physical condition, the patient is not able to give informed consent

Exclusion Criteria Age < 18