The goal of this prospective observational study is to investigate the feasibility of using doppler point-of-care ultrasound on the femoral artery with a portable device to assess the presence of a pulse in patients suffering from cardiac arrest in the out-of-hospital environment. The main question is how often researchers are successful in acquiring the necessary ultrasound signal in the out-of-hospital environment.
In this prospective observational study, a dedicated research team will be dispatched to cardiac arrest patients treated in the prehospital environment by emergency medical services (EMS). The team will use a portable ultrasound device to identify the femoral artery and conduct a pulsed wave (PW) doppler measurement during chest compressions as well as during chest compression pauses for rhythm analysis and save the recorded images. These ultrasound pulse checks will be conducted in parallel with the normal treatment of the patient, including manual pulse checks, and will only be conducted if ultrasound is possible without interference in the resuscitation. All treatment decisions will rest with the treating EMS team.
Study Type
OBSERVATIONAL
Enrollment
75
Point-of-care ultrasound will be used to image the femoral vessels and to perform a pulsed-wave doppler measurement of blood flow during chest compressions and during pauses for rhythm and manual pulse checks.
Emergency Medical Service of Vienna
Vienna, Austria
Feasibility of femoral artery doppler ultrasound
If an ultrasound image of the femoral artery of sufficient quality for Doppler ultrasound can be obtained, the primary outcome will be considered to be positive.
Time frame: During cardiac arrest, up to 45 minutes
Time until ultrasound signal acquisition
The time until successful acquisition of the doppler ultrasound signal will be measured in 2-minute CPR-intervals and 30-second intervals (e.g. second CPR-interval, first 30 seconds).
Time frame: During cardiac arrest, up to 45 minutes
Discordance between doppler ultrasound and manual pulse checks.
The presence of a doppler ultrasound flow signal during rhythm analysis and the result of the manual pulse check that is performed in parallel by the treating EMS team will be evaluated and analyzed for discordance.
Time frame: During cardiac arrest, up to 45 minutes
Correlation of the result of manual pulse checks with doppler peak systolic velocity
The correlation of the result of manual pulse checks performed by the treating EMS team with the peak systolic velocity measured by doppler ultrasound will be analyzed.
Time frame: During cardiac arrest, up to 45 minutes
Patient factors influencing probability of successful doppler ultrasound image acquisition
Patient factors sex, age, approximated bodyweight and suspected cause of cardiac arrest will be analyzed for correlation with successful doppler ultrasound image acquisition.
Time frame: After cardiac arrest, through study completion (a maximum of 1 year)
Inter-observer variability in determining the quality of the doppler ultrasound signal.
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The sonographer on site will assess the quality of the acquired doppler ultrasound images, as well as two ultrasound experts who will be blinded to the performing sonographer. The difference between these assessments will be analyzed.
Time frame: After cardiac arrest, through study completion (a maximum of 1 year)