Point-of-care ultrasonography during rescue operations on board a Polish Medical Air Rescue helicopter.

Point-of-care ultrasound examination has been increasingly widely used in pre-hospital care. The use of ultrasound in rescue medicine allows for a quick differential diagnosis, identification of the most important medical emergencies and immediate introduction of targeted treatment. Performing and interpreting a pre-hospital ultrasound examination can improve the accuracy of diagnosis and thus reduce mortality. The authors' own experiences are presented in this paper, which consist in using a portable, hand-held ultrasound apparatus during rescue operations on board a Polish Medical Air Rescue helicopter. The possibility of using an ultrasound apparatus during helicopter rescue service allows for a full professional evaluation of the patient's health condition and enables the patient to be brought to a center with the most appropriate facilities for their condition.

Introduction

Point-of-care ultrasound has been increasingly widely used in pre-hospital care. This is mainly due to advancing miniaturization of equipment and the introduction of shortened examination protocols. The use of an ultrasound apparatus in hospital emergency units has already become a standard. Performing and interpreting a prehospital ultrasound examination can improve the accuracy of diagnosis and thus reduce mortality(.

The authors’ own experiences are presented in this paper, which consist in using a portable, hand-held GE Vscan ultrasound apparatus during rescue operations on board a Polish Medical Air Rescue (MAR) helicopter.

Case description

The MAR team was called to help a 40-year-old female who was involved in a road accident in which two passenger cars collided head-on at a great speed. First, a physical examination according to the international trauma life support protocol (ITLS) was performed. The patient was unconscious, respiratorily insufficient, hemodynamically stable, with a stable pelvis and normal limb contours. After analgosedative and muscle relaxant drugs were administered endotracheal intubation was performed. The correct placement of the tube was confirmed with a standard capnography test. During auscultation it was noted that normal vesicular sound was diminished on the left side. Additionally, the correct depth of endotracheal tube placement was checked again. Due to the nature of the injuries and the condition of the victim the physician decided to immediately transport her by air to a trauma center. During the flight, as part of an extended diagnostic investigation an ultrasound examination of the chest and abdomen was conducted using simplified protocols: FATE (focused assessment transthoracic echocardiography) and eFAST (extended focused assessment sonography in trauma). In an apical view echocardiography examination a fluid reservoir with mixed echogenicity was noticed, which prevented the heart from being visible. Taking into account the mechanism of the trauma and the results of the simplified ultrasound examination, diaphragm rupture and the displacement of viscera into the chest was suspected. A positive result of the FAST examination was also found.

The staff of the trauma center was notified by radio of the time of arrival and of a priority status of the patient on board. Detailed imaging tests conducted later confirmed the MAR physician's initial diagnosis. The victim was qualified for an urgent operation.

Discussion

The case described testifies to the unique opportunities brought by ultrasound diagnostics in pre-hospital help. It is the only imaging test that can be used in such conditions.

It was a valuable addition to the physical examination in that it helped find causes of the health emergency. The versatility of this method allows for comprehensive diagnostics and an insight both into the anatomy and function of internal organs (echocardiography examination).

Noise and poor lighting can make it difficult or impossible to perform a comprehensive physical examination. Invisible diaphragm in the upper left quadrant of the abdomen in the eFAST examination and a fluid reservoir in the apical view, combined with the mechanism of the trauma, enabled the air rescue physician to arrive at a probable diagnosis. The use of ultrasound allowed for the immediate exclusion of other serious pathologies, which could have resulted from the trauma mechanism described. Despite circulatory and respiratory instability no invasive interventions (pleural drainage) were undertaken, which in this case could have exacerbated the patient's condition. They could be avoided thanks to the information provided by the imaging test. In multi-organ trauma some dysfunctions can be overlooked during the initial examination; therefore monitoring the condition of the victim also during transport is necessary in order to be able to notice any dangerous pathologies as soon as possible. In the case described the key vital functions of the patient were monitored using an ultrasound apparatus.

Until recently the use of ultrasound had been possible only in hospital conditions. Technological revolution which took place over the last few years resulted in the availability of small and light devices that are easy to accommodate in the limited operational space of a medical helicopter (fig. 1) and can even be carried in the resuscitation equipment bag. However, the small size of the apparatus and screen as well as the fact that only one probe is available limit the scope of detailed diagnostic investigation.

Fig. 1

The interior of the Polish Medical Air Rescue helicopter

Between November 16th 2013 and June 16th 2014 the MAR staff from the Cracow and Sanok bases used such a miniaturized ultrasound apparatus (GE Vscan) (fig. 2).

Fig. 2

The place for the ultrasound apparatus during medical rescue operations

Ultrasound examination performed in the helicopter and on the scene of the accident was a big challenge for the rescue team physician. The difficulties were associated with the extraordinary circumstances in which the examination was conducted. Daylight, motion, turbulences and difficult access to the victim made the situation considerably different from the comfortable conditions of the diagnostics room and could have had an influence on the quality of imaging(.

The key issue in a point-of-care ultrasound examination is the competence of the individuals performing it. It is of extraordinary importance, since the examination is usually carried out by physicians who are not radiologists or cardiologists.

In the case described the examination was carried out by the MAR physician, who has performed point-of-care examinations in patients in the state of medical emergency for two years after taking a specialist course.

According to the literature there is convincing evidence that the diagnosis delivered by medical air rescue physicians who have undergone training in ultrasound examination targeted at medical emergencies (pneumothorax, free fluid in the abdominal cavity, pericardial tamponade, cardiac arrest, severe heart failure) in most cases overlapped with the assessment of radiologists and cardiologists(.

Before the ultrasound apparatus was rented the MAR staff from the Cracow and Sanok base participated in a one-day course to gain basic knowledge and skills involved in the diagnosis of pathologies leading to medical emergencies.

In the case described a comprehensive ultrasound examination was performed on the basis of simplified FATE and FAST protocols(. These protocols were created for examinations in critical situations such as circulatory and respirator y insufficiency or trauma. Their simple design is supposed to help the physician (who is neither a radiologist nor a cardiologist) to carry out the examination smoothly in just a few minutes. It is not a detailed examination, but it is targeted at finding certain pathologies responsible for the patient's serious condition and should be, if possible, verified by a physician specializing in imaging techniques. In this context the FEEL protocol (focused echocardiographic evaluation in life support), which is frequently used in rescue medicine during cardiopulmonary resuscitation, is also worth mentioning.

In order to make it easier for physicians to perform the examinations and archive the most important dysfunctions a special form was compiled in cooperation with Dr. Dorota Sobczyk from the Critical USG Internet service (www.criticalusg.pl) (fig. 3), which has proved useful in practice so far.

Fig. 3

Urgent ultrasound examination form

Summary

The case described by the authors shows the extraordinary potential of ultrasound in pre-hospital diagnosis and monitoring of patients in a state of medical emergency. The use of ultrasound is a valuable addition to the physical examination and facilitates immediate diagnosis of many potentially critical pathologies, thus accelerating the introduction of causal treatment. Ultrasound-based diagnostic investigation can influence the choice of hospital to which the patient should be brought (tab. 1).

Tab. 1

Summary of applications of ultrasound in diagnostics on board an MAR helicopter

The use of a portable ultrasound apparatus on board a rescue helicopter can contribute to:	the detection of pneumothorax (lack of possibility of auscultating the patient during the flight)
	the detection of free fluid in the abdominal cavity – this gives high priority to the patient in the hospital
	the detection of ascending aorta dissection – changing the target hospital to the one with heart surgery services
	the diagnosis of an acute right ventricular failure
	the detection of cardiac tumors (myxomas, etc.)
	the assessment of hypovolemia by measuring inferior vena cava
	the assessment of the optic nerve sheath for an estimation of intracranial pressure
	the assessment of the presence of fluid in the pleural cavity
	the decisions on the prioritization of patients during a massive emergency event based on their condition (help in re-triage)
	the detection of cardiac tamponade
	the assessment of cardiac muscle contractility
	the monitoring of the pharmacological treatment used and its influence on the cardiovascular system