It is estimated that Point-of-Care Ultrasound (POCUS) is currently in use by 4.1% of EMS agencies and 21.7% are considering implementation. The medical uses of POCUS include: out of hospital cardiac arrest, termination of resuscitation, pulseless electrical activity (PEA), shock states, pericardial effusion, aortic aneurysm and dissection, acute pulmonary emboli, obstetrics, acute dyspnea and others. POCUS may be useful in pericardiocentesis, needle decompression, confirmation of endotracheal tube placement, and similar invasive procedures. A survey of 198 EMS medical directors cited equipment and training costs, challenges in training, transport times, delay in receiving definitive care, scope of practice issues, absence of evidence, regulatory factors, and administrative/medical control approval as barriers to implementation. Naturally, the goal is to achieve improved patient outcomes.
Think about the list of clinical indications. POCUS in cardiac arrest has been associated with pauses in compressions greater than 10 seconds, which has a demonstrated negative impact on survival. Conversely, a prospective pre-hospital study revealed that 35% of patients with electrocardiographic evidence of asystole and 58% with PEA actually had coordinated cardiac movement. The changes in therapy, based in part on this information, resulted in statistically significant increased survival. Some have compared POCUS to the implementation of 12-lead electrocardiography and telemetry in the field. The EKGs are used to detect ST Elevated Myocardial Infarction (STEMI) and facilitate rapid, appropriate intervention. STEMI protocols coupled with site specific access provide a systematic basis for regionalized care. This has resulted in a quantifiable improvement in survival for these patients. The use of ultrasound in trauma patients has become widely used by emergency physicians. ACEP has developed “Emergency Ultrasound Fellowship Guidelines”. To achieve “expert” status to be involved in a study reviewing POCUS lung scans, physician participants reviewed over 1,000 scans. What sort of training is used for prehospital personnel?
Formal training for ultrasound professionals is extensive and requires significant academic preparation. The training for other healthcare professionals varies immensely. Some programs are measured in hours or days. It is the opinion of some, that paramedics can be trained to interpret lung scans in 10 minutes. A recent feasibility study looked at POCUS performed by paramedics on non-traumatic patients with respiratory distress. Paramedics received two hours of training consisting of a 20 minute video with the remainder of the time spent in a workshop. The product manual for the device used in the study was 181 pages. There were three hypotheses in the study: paramedics can obtain adequate images; images can be transmitted in real time; physicians can interpret the field images reliably; and, the information is clinically useful. The only hypothesis that proved feasible was that images can be successfully obtained. Images were transmitted to the ED and many were not of adequate quality to be read. This generated the thought that paramedics might interpret the images on scene. Technical issues related to battery life, display, software and transmission limited effectiveness. The prehospital environment poses challenges for image acquisition that must be addressed with training and technology. Think about 12-leads.
Prior to the implementation of 12-lead EKGs, paramedics were already trained in EKG acquisition, identification of dysrhythmias, and algorithm based treatments. Using 12-leads is merely an extension of a pre-existing skill set. There is no experiential basis to prepare us for POCUS. We know how to compare EKG machines. Do we know what safety issues apply to ultrasounds? Do the mechanisms of potential biologic damage from ultrasound (radiation force, thermal interactions and cavitation) mean anything to us? For transmission, how are security and HIPAA compliance achieved?
If we don’t know what we don’t know, how do we know what we need to learn? POCUS may be a useful tool in the prehospital armamentarium, but it must be approached in an academically sound manner that guarantees operator proficiency, resulting in improved patient outcomes.
- Arshad F. Prehospital Ultrasound. JEMS, February 2018, 55-58
- Wesley Keith & Wesley Karen Focus on POCUS. JEMS, March 2018, 25
- Becker TK, Martin-Gill C, et alia, Feasibility of Paramedic Performed Prehospital Ultrasound in Medical Patients with Respiratory Distress. Prehospital Emergency Care 2018; 22: 175-179
- Wagner PR & Hedrick WR Point-of-Care Ultrasound Fundamentals,McGraw Hill, New York, 2015