Industry voice: Air medical point-of-care ultrasound

Benefits of point-of-care ultrasound

Our flight crews were as proficient in the eFAST examination as our Level I Trauma Center colleagues

In our previous research, we showed that a highly trained and well-motivated flight crew could successfully complete the didactic and practical education required to adequately perform and interpret the POCUS eFAST examination on nearly 500 trauma patients with a degree of success equal to those of the trauma team at the accepting Level I Trauma Center. Each of these studies showed that our flight crews were well within the accepted sensitivity and specificity for the examination. The challenge was determining if the flight crew could maintain their level of proficiency with the number of requested trauma flights and CME hours that we had developed in the POCUS program. Throughout the course of both studies and the five years separating them, we maintained the acceptable <20 per cent clinical misinterpretation rate with very little statistical difference. The misinterpretation rate is directly related to the operational and interpretive errors performed by the flight crews. Our analysis of the misinterpretation rate shows that the number of POCUS eFAST examinations performed by the flight crews and the current CME program allows the flight crews to remain proficient in performing and interpreting the examination with no improvement or degradation in their skill level. Observing that flight crews did not perform eFAST examinations on numerous trauma patients that underwent aeromedical transport, for varied acceptable reasons, leads us to believe that the current overall trauma patient flight volume is significant to maintain our program. We are in the process of increasing the number of POCUS examinations from those trauma patients being transported, without negatively effecting the flight crews operational and safety related responsibilities.

Our flight crews have shown that they are able to successfully interpret their POCUS eFAST results and identify potential life-threatening conditions – such as pneumothorax, hemothorax, hemopneumothorax, and free abdominal or pelvic fluid – during helicopter transport of severely injured trauma patients. The early recognition of these conditions has led to an upgrade in the level of trauma activation (alpha and bravo alerts), better preparation by the trauma team prior to the patient’s arrival, early activation of the massive transfusion protocol, and occasionally the patient being transported directly to the operating room (DOR) while bypassing the trauma bay. From an air medical systems standpoint, the accuracy in the flight crew’s ability to interpret potential life-threatening conditions has led to the administration of pre-hospital blood in patients with a positive eFAST identifying free fluid with accompanying signs and symptoms of shock. One of the most significant factors that we observed with the use of POCUS eFAST examination is that no patient underwent an inadvertent air medical needle-thoracostomy or other form of pleural decompression by the flight crews. In comparison, the trauma patients transported by ground emergency medical services (EMS) showed the presence of needle-decompression far exceeds the number of actual tension pneumothoraces. 

As we anticipated in our 2017 research, the POCUS devices have become much more compact and lighter, and come with greatly improved technology. Aside from all of these advances, the price has dramatically decreased. Our study in 2017 was performed using a Sonosite M-Turbo POCUS device that weighed 8lbs (3.6kg) with two manually interchangeable transducers. At that time, it retailed for $25,000 and currently a refurbished model is $12,500. During our 2022 research we had changed to a more compact device, the Butterfly iQ, which offers a single probe that contains a linear, phased array and curvilinear transducers, and weighs 0.69lbs (313g). Today’s cost is $2,700 and a $420/year membership serves as a user license that allows for storage of images. We evaluated each device prior to the start of the study and found that neither interfered with the aircraft's avionics nor did the electrical system of the aircraft cause artifacts with the ultrasound device. In comparing the two devices, flight crews determined that the Butterfly iQ was superior based upon weight, size, ease of use, and portability in and out of the aircraft. It was the opinion of the flight crew that the POCUS device should be so easily portable that it could be used outside the aircraft and brought directly to where a patient may be entrapped or where life-saving interventions are being performed with ease. 

Potential negatives of air medical point-of-care ultrasound

I do not feel that there are any absolute negative implications in the performance of the eFAST POCUS evaluation in any trauma patient as a plethora of evidence clearly demonstrates the benefits. However, as we move this evaluation into the air medical environment, several concerns stand at the forefront of performing this diagnostic modality. In developing our POCUS program, we did not want to influence the key operational and safety-related tasks performed by the flight crew during take-off, flight and landing. Some of these key tasks are completed during the five minute window of take-off or landing, are directly related to the safety of the patient and crew, and were non-negotiable in eliminating or altering with the implementation of the POCUS program. To address these key safety windows, we established that POCUS would not be performed during this five minute window. These ‘safety windows’ continue to be an important part of the flight program but have decreased the number of eFAST POCUS evaluations performed particularly during flight times that are <15 minutes long. 

With addition of a new procedure, we had significant concerns that the flight crew’s scene times during trauma flights would be adversely affected. As we rolled-out our program to the flight crews, we also implemented an update entitled, ‘Care and evaluation of the trauma patient’. By focusing on the most up-to-date trauma care principals, we avoided any concern for an increase in the flight crew’s scene times and actually saw a two minute average decrease in scene times following full implementation of the POCUS program. This is a true testament of our crew’s ability to embrace new patient care modalities and technology while continuing to meet the standards of care and transport. 

Patient packaging, aircraft compartment configuration, and stretcher design all posed some degree of difficulty in obtaining access to the ‘POCUS windows’ required to successfully perform the eFAST examination. During scene flights, if EMS personnel have already packaged the patient without first performing proper exposure, it renders performing the eFAST examination much more difficult, if not impossible. The patient configuration in our aircraft places the patient’s right side fairly close to the port bulkhead of the aircraft making access to the abdominal right upper quadrant (RUQ) highly dependent upon the body mass index (BMI) of the patient. Unfortunately, this RUQ (Morrison’s pouch) is the most dependent area of the abdominal compartment and a key window in the identification of free abdominal fluid in trauma patients. We explored the possibility of using an alternative, anterior window in these patients but quickly identified that this ultrasonic plane is inappropriate for the identification of free abdominal fluid in the eFAST examination. 

Summary

The initial FAST examination was developed to facilitate rapid transfer of hypotensive trauma patients with free abdominal fluid to the operating room (OR) for definitive surgical care. With the addition of the cardiac window for identification of pericardial effusion/tamponade, several pleural windows for the identification of pneumothorax, and lastly expansion of the abdominal windows above the diaphragm for the diagnosis of a traumatic hemothorax, today’s eFAST allows providers the rapid identification of the most common, life-threatening, traumatic injuries. Despite this ever-expanding modality, the most important aspect of patient care remains the history and physical examination. As educators, we continue to remind all of our learners that they have to actually see and touch the patient to obtain a complete evaluation.

Flight crews obtain the most benefit from performing eFAST examinations on patients who are hypotensive or symptomatic

Flight crews obtain the most benefit from performing eFAST examinations on patients that are hypotensive or symptomatic, because the positive finding during the POCUS evaluation alters the treatment priority and algorithms guiding patient care. Currently, flight crews perform the evaluation on all trauma patients that present for evaluation and care. The methodology of performing POCUS evaluations on all trauma patients has assisted us in becoming more proficient clinical POCUS providers. Becoming more proficient in POCUS has come with a ‘cost’ and I must let you decide if it is clinically appropriate. By performing POCUS examinations of every trauma patient, we have greatly increased the number of normal examinations that we perform on relatively asymptomatic patients, I certainly do not want to take away the importance of ‘knowing normal’ in ultrasound education and training, but does this have the potential to make flight crews more complacent when performing a POCUS examination. The dramatic increase in the number of normal examinations may cause us to think of POCUS as a mundane examination and push us into a pattern of just going through the steps without the appropriate attention to detail that is certainly required for this clinical evaluation. I think that this is a reasonable question to ponder as the vast majority of inaccurate evaluations, if not all, are based on operator error or misinterpretation. 

As you progress into developing your own air medical POCUS program or continue to evaluate your current ongoing program, I hope that our successes and struggles can assist you in providing highly-skilled patient care to those patients experiencing a traumatic injury.