The use of focused assessment with sonography for trauma (FAST) by a prehospital air medical team in the trauma arrest patient

An Air Medical Approach to In-Flight Cardiac Arrest Management

OBJECTIVE

Cardiac arrest during air medical transport is a complex and challenging issue, with unique factors such as limited physical space with restricted access to patients and equipment, small transport teams, limited resources, clinical isolation, effects of altitude, and the need for rapid decision making. The American Heart Association proposed 10 steps to improve outcomes of in-hospital cardiac arrest and serve as the framework for this article. This article aimed to explore these unique challenges and propose a contextual approach that might serve as the basis for improvement projects looking to improve outcomes for affected patients.

METHODS

This article represents a narrative review of the subject to consolidate the issue of cardiac arrest in the air medical setting specifically. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses literature search extension was used to guide the search strategy and methodology. The applicable items in the literature were selected through searches of the PubMed and Google Scholar databases. The Medical Subject Headings search terms used included "cardiopulmonary resuscitation" or "heart arrest" and "air ambulance" or "air medical transport,'' yielding 477 results. Screening for relevant results for inclusion was based on the relevance of the title or abstract. Articles not written in English or German or addressing commercial air transport were excluded. The reference lists of the included articles were searched for additional literature not included in the original search.

RESULTS

Three distinct phases are arbitrarily identified by the authors, and the results are discussed under the following headings: pre-arrest, intra-arrest, and post-arrest phases. The pre-arrest phase is characterized by a wide array of concepts such as appropriate goals of care, advanced preparation and action, good clinical governance, patient assessment and handover, system design and ergonomics, sterile cockpit management, appropriate alarm management, and contingency planning in the case of failed resuscitation. The intra-arrest phase is characterized by the contextualization of the usual resuscitation approach, and specific recommendations for immediate nonresuscitative actions, history, hazards, help, airway, breathing, circulation, drugs, and reversible causes are suggested. The post-arrest phase highlights the vulnerable nature of the post-cardiac arrest patient in the air medical setting. Specific considerations regarding postresuscitation care and practitioner well-being are highlighted.

CONCLUSION

This article outlines a systematic approach to various physical, clinical, mental, and systemic factors that can be used during various phases of the transport journey as well as the individual patient journey. This overview sensitizes individual clinicians or program directors to the factors needing consideration when looking to improve cardiac arrest patient outcomes.

Helicopter Emergency Medical Services Performed Extended Focused Assessment With Sonography: Training, Workflow, and Sustainable Quality

The extended focused assessment of trauma (EFAST) examination is an invaluable tool for the initial evaluation of the trauma patient. Miniaturization of ultrasound has enabled helicopter emergency medical services (HEMS) to use point-of-care ultrasound to care for trauma patients on scene. Our study demonstrated that HEMS crews accurately performed EFAST examinations after the implementation of a novel HEMS EFAST workflow, multifaceted training, and ongoing quality assurance. The HEMS crews' overall sensitivity was 53%, and specificity was 98%. The obtained image quality was highest for the lung, cardiac, and right upper quadrant components of the EFAST. Our results suggest that with a structured multifaceted training program, user-friendly workflow, and ongoing quality assurance, HEMS crews can perform EFAST examinations safely and reliably in the field. This would allow HEMS crews to detect life-threatening, time-sensitive conditions such as a pneumothorax, pericardial effusion, and intraperitoneal hemorrhage. HEMS EFAST has the potential to triage certain trauma patients directly to the operating room or newly emerging hybrid suites, bypassing the emergency room and saving crucial time.

Prehospital ultrasound of the abdomen and thorax changes trauma patient management: A systematic review

BACKGROUND

Ultrasound examination of trauma patients is increasingly performed in prehospital services. It is unclear if prehospital sonographic assessments change patient management: providing prehospital diagnosis and treatment, determining choice of destination hospital, or treatment at the receiving hospital.

OBJECTIVE

This review aims to assess and grade the evidence that specifically examines whether prehospital ultrasound (PHUS) of the thorax and/or abdomen changes management of the trauma patient.

METHODS

A systematic review was conducted of trauma patients who had an ultrasound of the thorax or abdomen performed in the prehospital setting. PubMed, MEDLINE, Web of Science (CINAHL, EMBASE, Cochrane Central Register of Controlled Trials) and the reference lists of included studies were searched. Methodological quality was checked and risk of bias analysis performed, a level of evidence grade was assigned, and descriptive data analysis performed.

RESULTS

992 unique citations were identified, which included eight studies that met inclusion criteria with a total of 925 patients. There are no reports of randomised controlled trials. Heterogeneity exists between the included studies which ranged from a case series to retrospective and prospective non-randomised observational studies. Three studies achieved a 2+ Scottish Intercollegiate Guidelines Networks grade for quality of evidence and the remainder demonstrated a high risk of bias. The three best studies each provided examples of prehospital ultrasound positively changing patient management.

CONCLUSION

There is moderate evidence that supports prehospital physician use of ultrasound for trauma patients. For some patients, management was changed based on the results of the PHUS. The benefit of ultrasound use in non-physician services is unclear.

Prospective evaluation of prehospital trauma ultrasound during aeromedical transport

BACKGROUND

Ultrasound is widely considered the initial diagnostic imaging modality for trauma. Preliminary studies have explored the use of trauma ultrasound in the prehospital setting, but the accuracy and potential utility is not well understood.

OBJECTIVE

We sought to determine the accuracy of trauma ultrasound performed by helicopter emergency medical service (HEMS) providers.

METHODS

Trauma ultrasound was performed in flight on adult patients during a 7-month period. Accuracy of the abdominal, cardiac, and lung components was determined by comparison to the presence of injury, primarily determined by computed tomography, and to required interventions.

RESULTS

HEMS providers performed ultrasound on 293 patients during a 7-month period, completing 211 full extended Focused Assessment with Sonography for Trauma (EFAST) studies. HEMS providers interpreted 11% of studies as indeterminate. Sensitivity and specificity for hemoperitoneum was 46% (95% confidence interval [CI] 27.1%-94.1%) and 94.1% (95% CI 89.2%-97%), and for laparotomy 64.7% (95% CI 38.6%-84.7%) and 94% (95% CI 89.2%-96.8%), respectively. Sensitivity and specificity for pneumothorax were 18.7% (95% CI 8.9%-33.9%) and 99.5% (95% CI 98.2%-99.9%), and for thoracostomy were 50% (95% CI 22.3%-58.7%) and 99.8% (98.6%-100%), respectively. The positive likelihood ratio for laparotomy was 10.7 (95% CI 5.5-21) and for thoracostomy 235 (95% CI 31-1758), and the negative likelihood ratios were 0.4 (95% CI 0.2-0.7) and 0.5 (95% CI 0.3-0.8), respectively. Of 240 cardiac studies, there was one false-positive and three false-negative interpretations (none requiring intervention).

CONCLUSIONS

HEMS providers performed EFAST with moderate accuracy. Specificity was high and positive interpretations raised the probability of injury requiring intervention. Negative interpretations were predictive, but sensitivity was not sufficient for ruling out injury.

Clinical applicability of real-time, prehospital image transmission for FAST (Focused Assessment with Sonography for Trauma)

We evaluated a real-time, prehospital ultrasound image transmission system for use in focused assessment with sonography for trauma (FAST). The wireless, real-time ultrasound image transmission system comprised an ultrasound scanner with a convex abdominal transducer and a notebook computer connected to a 3 G wireless network for video data transmission. In our simulation experiment, ultrasonography was performed by emergency medical technicians (EMTs) on a human body phantom with simulated haemoperitoneum. Transmitted ultrasound video clips were randomly rearranged and presented to emergency physicians to make a diagnosis of haemoperitoneum. A total of 21 ultrasound video clips was used and 13 emergency physicians participated in the study. The sensitivity and specificity were 90.0% (95% Confidence Interval, CI, 83.5-94.6) and 85.3% (95% CI 78.4-90.7) respectively, and the accuracy of detecting abnormal ultrasound results was 87.7% (95% CI 83.8-91.6). Diagnosis of hemoperitonuem in trauma patients by an emergency physician based on the transmitted video images of FAST performed by an EMT is feasible, and has an accuracy of about 88%.

Prehospital emergency ultrasound: a review of current clinical applications, challenges, and future implications

Imaging modalities in the prehospital setting are helpful in the evaluation and management of time-sensitive emergency conditions. Ultrasound is the main modality that has been applied by emergency medical services (EMS) providers in the field. This paper examines the clinical applications of ultrasound in the prehospital setting. Specific focus is on applications that provide essential information to guide triage and management of critical patients. Challenges of this modality are also described in terms of cost impact on EMS agencies, provider training, and skill maintenance in addition to challenges related to the technical aspect of ultrasound.

Trauma ultrasound in civilian tactical medicine

The term “tactical medicine” can be defined in more than one way, but in the nonmilitary setting the term tactical emergency medical services (TEMS) is often used to denote medical support operations for law enforcement. In supporting operations involving groups such as special weapons and tactics (SWAT) teams, TEMS entail executing triage, diagnosis, stabilization, and evacuation decision-making in challenging settings. Ultrasound, now well entrenched as a part of trauma evaluation in the hospital setting, has been investigated in the prehospital arena and may have utility in TEMS. This paper addresses potential use of US in the tactical environment, with emphasis on the lessons of recent years' literature. Possible uses of US are discussed, in terms of both specific clinical applications and also with respect to informing triage and related decision making.

Diagnostic accuracy of focused assessment with sonography for trauma (FAST) examinations performed by emergency medical technicians

OBJECTIVE

We aimed to assess the diagnostic accuracy of focused assessment with sonography for trauma (FAST) examinations when used by emergency medical technicians (EMTs) to detect the presence of free abdominal fluid.

METHODS

Six level 1 EMTs (similar to intermediate EMTs in the United States) who worked at a tertiary emergency department in Korea underwent an educational program consisting of two one-hour didactic lectures that included the principles of ultrasonography, the anatomy of the abdomen, and two hours of hands-on practice. After this educational session, the EMTs performed FAST examinations on a convenience sample of patients from July 1 to October 5, 2009. These patients also received an abdominal computed tomography (CT) scan regardless of their chief complaints. The CT findings served as the definitive standard and were interpreted routinely and independently by emergency radiologists who were blinded to the study protocol. In addition, the EMTs were blinded to the CT findings. A positive CT finding was defined as the presence of free fluid, as interpreted by the radiologist. The sensitivity, specificity, predictive values, and their 95% confidence intervals (CIs) were calculated. Informed consent was obtained from all participating patients.

RESULTS

Among the 1,060 eligible patients with abdominal CT scans, 403 patients were asked to participate in the study, and 240 patients agreed. Of these 240 patients, 80 (33.3%) had results showing the presence of free fluid. Fourteen patients had a significant amount of peritoneal cavity fluid, 15 had a moderate amount of peritoneal cavity fluid, and 51 had a minimal amount of peritoneal cavity fluid. Compared with the CT findings, the diagnostic performance of the FAST examination had a sensitivity of 61.3% (95% CI, 50.3%-71.2%), specificity of 96.3% (95% CI, 92.1%-98.3%), positive predictive value of 89.1% (95% CI, 77.0%-95.4%), and negative predictive value of 83.2% (95% CI, 76.9%-88.2%). For a significant or moderate amount of peritoneal cavity fluid, the sensitivity was considerably higher (86.2%).

CONCLUSION

EMTs in Korea showed a high diagnostic performance that was comparable to that of surgeons and physicians when detecting peritoneal cavity free fluid in a Korean emergency department setting. The validity of FAST examinations in prehospital care situations should be investigated further.

Prehospital ultrasound in emergency medicine: incidence, feasibility, indications and diagnoses

BACKGROUND

Sonography is an established diagnostic procedure in hospitals, but is not routinely used in prehospital emergency medicine. Several studies have addressed the use of ultrasound during helicopter flights and in emergency rooms, few in prehospital settings, but most focused on abdominal blunt trauma. Several case reports describe crucial decisions distinguished by ultrasound.

METHODS

In this study, four different handheld ultrasound systems in 4 helicopters and one emergency vehicle were used over a cumulative period of 3 years. Incidence, feasibility, indication, diagnoses and exploration time (in subgroups) were investigated in an overall profile of emergency patients, encompassing the area of internal medicine.

RESULTS

On 971 missions ultrasound systems were available. In 17% of the cases ultrasound was considered valuable, in 144 patients (14.8%) sonographic studies were performed. Additional information could be given in 130 cases (90%). Compared with the available clinical data (return rate of 76%) there were no false-positive findings during this study, resulting in a specificity and positive predictive value of 100%, showing this technique to be reliable. Sensitivity was 85%, accuracy was 96% and negative predictive value was 95%.

CONCLUSION

Ultrasound is the only imaging modality and a useful diagnostic tool in prehospital emergency medicine. Helpful information can be provided in at least one of six cases (or even more) in a trauma-dominated collective. Examination time is short; it will not significantly delay medical care. Ultrasound examination could improve triage in cases of more than one patient in disaster medicine, but further studies are necessary.

Does prehospital ultrasound improve treatment of the trauma patient? A systematic review

Ultrasound (US) has been used for in-hospital evaluation of the trauma victim for many years. The outcome in severely injured patients remains heavily influenced by initial life support and early care, as time plays a major role. Development of handheld, battery-powered, low-weight US machines has created the possibility of bringing US to the prehospital setting, thus gaining a potential for early diagnosis and treatment. The objective of this study was to systematically search the literature for evidence that prehospital US of the abdomen or thorax increases survival of trauma patients. The data regarding the use of US in the prehospital setting is sparse, often of low quality and describing a broad variety of patients and clinical challenges. Therefore, from an evidence point of view it is not possible to answer the objectives in this review. In the prehospital setting, rapid assessment plays an important role, as initial life support and early surgical care influences the outcome of the severely injured patient. Time is especially crucial in blunt abdominal trauma and penetrating truncal injuries. Several studies in this review showed that prehospital US is feasible and that the procedure is highly reliable in detection of haemoperitoneum or haemopericardium compared with the low accuracy of physical examination and haemodynamic measurements. An early diagnosis will provide the prehospital physician with the knowledge to prioritize the relevant initial treatment and to choose the closest appropriate hospital and transportation form. There is currently no evidence in the literature that prehospital US of the abdomen or thorax improves treatment of trauma patients.

Portable ultrasonography in mass casualty incidents: The CAVEAT examination

Ultrasonography used by practicing clinicians has been shown to be of utility in the evaluation of time-sensitive and critical illnesses in a range of environments, including pre-hospital triage, emergency department, and critical care settings. The increasing availability of light-weight, robust, user-friendly, and low-cost portable ultrasound equipment is particularly suited for use in the physically and temporally challenging environment of a multiple casualty incident (MCI). Currently established ultrasound applications used to identify potentially lethal thoracic or abdominal conditions offer a base upon which rapid, focused protocols using hand-carried emergency ultrasonography could be developed. Following a detailed review of the current use of portable ultrasonography in military and civilian MCI settings, we propose a protocol for sonographic evaluation of the chest, abdomen, vena cava, and extremities for acute triage. The protocol is two-tiered, based on the urgency and technical difficulty of the sonographic examination. In addition to utilization of well-established bedside abdominal and thoracic sonography applications, this protocol incorporates extremity assessment for long-bone fractures. Studies of the proposed protocol will need to be conducted to determine its utility in simulated and actual MCI settings.

Prehospital ultrasound by paramedics: results of field trial

OBJECTIVES

The objective was to determine if 9-1-1 paramedics trained in ultrasound (US) could adequately perform and interpret the Focused Assessment Sonography in Trauma (FAST) and the abdominal aortic (AA) exams in the prehospital care environment.

METHODS

Paramedics at two emergency medical services (EMS) agencies received a 6-hour training program in US with ongoing refresher education. Paramedics collected US in the field using a prospective convenience methodology. All US were performed in the ambulance without scene delay. US exams were reviewed in a blinded fashion by an emergency sonographer physician overreader (PO).

RESULTS

A total of 104 patients had an US performed between January 1, 2008, and January 1, 2009. Twenty AA exams were performed and all were interpreted as negative by the paramedics and the PO. Paramedics were unable to obtain adequate images in 7.7% (8/104) of the patients. Eighty-four patients had the FAST exam performed. Six exams (6/84, 7.1%) were read as positive for free intraperitoneal/pericardial fluid by both the paramedics and the PO. FAST and AA US exam interpretation by the paramedics had a 100% proportion of agreement with the PO.

CONCLUSIONS

This pilot study shows that with close supervision, paramedics can adequately obtain and interpret prehospital FAST and AA US images under protocol. These results support a growing body of literature that indicates US may be feasible and useful in the prehospital setting.

Use of ultrasound by emergency medical services: a review

Prehospital ultrasound has been deployed in certain areas of the USA and Europe. Physicians, emergency medical technicians, and flight nurses have utilized a variety of medical and trauma ultrasound assessments to impact patient care in the field. The goal of this review is to summarize the literature on emergency medical services (EMS) use of ultrasound to more clearly define the potential utility of this technology for prehospital providers.

FAST ultrasound as an adjunct to triage using the START mass casualty triage system: a preliminary descriptive system

OBJECTIVE

To determine whether the FAST examination might be a useful adjunct to simple triage and rapid treatment (START) in the secondary triage of mass-casualty victims already classified as delayed (Yellow).

METHODS

A retrospective chart review was conducted of all adult trauma patients evaluated by the trauma surgery service at a level 1 trauma center between January 1 and December 31, 2003. Patients were retrospectively triaged to one of three START categories: immediate (Red), delayed (Yellow), or expectant (Black). The FAST results were obtained from the medical records.

RESULTS

FAST results were available for 359 patients, of which 27 were classified as positive. Twenty (6.9%) of 286 patients retrospectively triaged as delayed (Yellow) had positive FAST studies. Of these, six underwent operative intervention within 24 hours of arrival. A total of 232 patients had both FAST and computed tomography (CT) studies performed, of which 19 FAST studies were inconclusive. In the remaining 213 patients, six of 27 had falsely positive studies, while 24 of 186 had falsely negative studies.

CONCLUSIONS

Portable ultrasound technology might have identified 20 delayed (Yellow) patients with evidence of hemoperitoneum, thereby expediting evacuation to definitive care. However, only 30% of these patients subsequently underwent an operative intervention within 24 hours of arrival. Both over- and undertriage were significant problems. As such, the current study does not support the routine use of FAST ultrasound as a secondary triage tool.

Future applications for emergency ultrasound

US has become an integral part of patient evaluation in emergency medicine. As discussed in this article, other potential uses for US are relatively early in their development. With the increased interest and study,however, there exists a real potential for US to be employed in an expanded clinical role in the evaluation of traumatically injured patients outside the standard FAST examination, for acute and chronic musculoskeletal injuries,and for triage of patients in disasters.

Fetal evaluation for transport by ultrasound performed by air medical teams: A case series

The air medical team has limited options when evaluating the obstetrical patient and assessing fetal health during air transport to a high-risk obstetrical unit. Traditionally, physical examination and a Doppler stethoscope have been used to determine fetal heart rates and movement. However, with the advent of portable ultrasound technology, new information about the mother and child are available to the air medical crew. The Fetal Evaluation for Transport with Ultrasound (FETUS) is a screening examination that consists of an evaluation of the fetal heart rate, position, and movement and general condition of the placenta. The examination can be repeated in flight with no acoustic distortion from rotor noise. The additional information can be advantageous when transport decisions need to be made or when conditions do not allow Doppler stethoscope use.

Trauma ultrasound feasibility during helicopter transport

OBJECTIVE

To evaluate the feasibility of performing a standard four-view focused abdominal sonography for trauma (FAST) examination during helicopter transport using a hand-carried ultrasound machine.

METHODS

In this prospective observational study, actual and simulated trauma patients were evaluated using the SonoSite 180 ultrasound machine by two air transport programs serving Level I trauma centers. FAST examinations were performed in flight by emergency medicine faculty, residents, flight nurses, and ultrasound technologists, who rated the difficulty posed by various factors using Likert scales (0 = not difficult to 5 = impossible). BK 117, Bell 230, and BO 105 medical helicopters flew in all aviating modes. Pilots were queried regarding avionics variations throughout the flights.

RESULTS

Ten flight sonographers performed 21 FAST examinations on 14 patients (five actual, nine simulated). The median Likert value for each parameter was 0 except for patient position, which was 1 (somewhat difficult). Interquartile ranges were 0-0 for vibration, bedding, IV catheters, monitor cables, and ventilator; 0-0.5 for backboard straps; and 0-1 for sunlight, patient position, spider straps, gurney straps, and clothing. Mean examination duration, was 3.0 minutes (range 1.5 to 5.5 minutes, SD 1.3). Pilots reported no effects on avionics in any flight mode.

CONCLUSION

The FAST examination using the SonoSite 180 in flight was rated by 10 evaluators to be performed easily. Examinations were conducted quickly and did not interfere with helicopter avionics. This digital ultrasound machine is the first one small enough to be used in most medical helicopters.