|Year : 2017 | Volume
| Issue : 1 | Page : 51-56
Bedside ultrasound (Part 2) - The FAST examination
Kishore Kumar Pichamuthu
Department of Critical Care, Christian Medical College, Vellore, Tamil Nadu, India
|Date of Web Publication||17-Feb-2017|
Kishore Kumar Pichamuthu
Department of Critical Care, Christian Medical College, Vellore - 632 004, Tamil Nadu
Source of Support: None, Conflict of Interest: None
In the setting of blunt or penetrating injury to the abdomen and chest, bedside ultrasound in the form of the extended-focused assessment with sonography for trauma (E-FAST) examination plays a vital role in rapid diagnosis of bleeding in the abdominal and thoracic cavities. Rapid diagnosis and intervention based on the diagnosis is associated with better treatment outcomes. E-FAST is rapid, can be done along with the primary and secondary survey without disrupting resuscitative measures, is noninterventional, and does not involve exposure to ionizing radiation. It can be used to detect hematoma in the intraperitoneal cavity and pelvis, hemothorax, pneumothorax, and pericardial effusion using eight standard views. The disadvantages are that it is operator dependent and requires some amount of training, and a negative E-FAST study does not necessarily exclude serious intra-abdominal injury.
Keywords: Extended-focused assessment with sonography for trauma, focused assessment with sonography for trauma, trauma, ultrasound
|How to cite this article:|
Pichamuthu KK. Bedside ultrasound (Part 2) - The FAST examination. Curr Med Issues 2017;15:51-6
| Introduction|| |
Ultrasound was first used in the assessment of patients with trauma in the 1970s. It has since become an integral part of the early management of trauma. Its use in this scenario is primarily in the form of the focused assessment with sonography for trauma (FAST) examination. FAST stands for focused assessment with sonography in trauma.,
Patients with trauma can have significant bleeding into the peritoneal, pleural, and pericardial spaces without demonstrating clinical signs that can be picked up in the initial physical examination. Imaging of the patient is hence required. Computed tomography (CT) imaging of the abdomen and chest would provide the best information regarding bleeding and organ injury. However, this is a time-consuming process which may not be appropriate in a situation where one is faced with a trauma victim with hypotension, where every minute counts. Bedside ultrasound in the emergency room is a good choice of first-line imaging because it does not require the patient to be transported and delivers management-changing information quickly (compared to X-rays and CT scans).,, Ultrasound of the abdomen is particularly useful in detecting blood in the intraperitoneal cavity and helps guide the decision to perform a laparotomy.,,
The FAST examination was an initially a four-point examination looking for fluid in the peritoneal and pericardial spaces but has now been extended to include screening for hemothorax and pneumothorax bilaterally. This format of examination is now called the extended FAST (E-FAST).
| Indications|| |
The E-FAST examination is performed on patients with
- Penetrating or blunt chest injury (major hemothorax and pneumothorax)
- Penetrating or blunt cardiac injury (pericardial effusion)
- Penetrating or blunt abdominal injury (intra-abdominal free fluid).,,
It can also be performed when the mechanism of blunt injury is not clear or the trajectory of penetrating injuries is unknown.
| Advantages of E-Fast|| |
- The advantages of E-FAST assessment with sonography for trauma examination ,,,, include the following
- It provides a quick diagnosis for acute abdominal injury. A quick diagnosis and early surgical intervention when indicated is associated with a better prognosis in trauma ,
- It is very useful in diagnosing hemoperitoneum
- It can be done at the bedside, without removing patients from the emergency department. This is particularly useful in an unstable, bleeding patient with hypotension
- It can be done while doing the primary and secondary survey and with resuscitative measures taking place simultaneously
- It can be repeated for serial examinations
- It leads to lesser instances of diagnostic peritoneal lavage and CT scans.
| Timing|| |
The FAST examination is performed immediately after the primary survey. It may have to be repeated within 10–15 min if the findings were not conclusive the first time.
| Procedure|| |
The patient should be supine. Head-up tilt of the entire bed may improve visualization of fluid in the pleural spaces and the pelvis while a head-down tilt will increase the sensitivity of finding fluid in the Morrison's pouch.
The convex abdominal probe or the echocardiography probe in abdomen mode can be used. These are low-frequency probes (1–5 MHz). The same probe can be used for all the views.
Eight views need to be acquired and interpreted to complete the E-FAST examination [Figure 1] and the sequential technique, and interpretation of each is as follows:
|Figure 1: The sequence of eight views that make up the extended-focused assessment with sonography for trauma examination.|
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Anterior chest view
The first view to be acquired screens the anterior chest for the presence of a pneumothorax. The probe is placed on the most nondependent area of one hemithorax. This is usually the 3rd or 4th intercostal space in the midclavicular line. The probe is placed perpendicular to the ribs with the marker dot facing headwards. The depth should be reduced to visualize only the chest wall and pleura. We usually start with a depth setting of 4 cm.
The probe should be positioned such that the cross section of at least two ribs should be visualized. These appear as oval hypoechoic structures with a bright upper surface. These ribs also cast a dark “shadow” behind them. Between these, the pleural line will be visible as a bright white line joining the posterior margins of the visualized ribs [Figure 2]. This is the interface of the parietal and visceral pleural layers. Below the pleural line, horizontal reverberation artifact lines may be noted and these are called A lines.
Close inspection of this pleural line should reveal a sliding movement with respiration. This is called lung sliding. In a pneumothorax, the visceral pleura no longer slides against the parietal pleura, leading to the absence of lung sliding. This absence of lung sliding with the presence of A lines below the pleural line suggests a pneumothorax. Sometimes, a lung point may be seen – the presence of an area of normal lung sliding adjacent to an area of no lung sliding seen on the same image.
The same view is then obtained on the opposite hemithorax and interpreted.
Right lower thorax view
The probe is then placed on the right midaxillary line at the 7th or 8th intercostal space with the dot marker facing headward. Since a number of rib shadows may interfere with the image, rotate the probe anticlockwise till it is aligned parallel to the ribs in the intercostal space. A view of the costophrenic angle must be obtained. The liver will be seen on one-half of the screen and the normal lung on the other half, separated by the diaphragm. The presence of a black area in the angle above and between the diaphragm and the chest wall separating it from the lung suggests pleural fluid and potentially a hemothorax [Figure 3]. The lower lobe of the lung may be seen floating in the fluid. Fluid collections on the superior surface of the liver between it and the diaphragm can also be visualized in this view.
|Figure 3: Right lower thoracic view showing liver on the right, jet black fluid inside the pleural space on the left with the lung floating in the fluid. “d” stands for diaphragm.|
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Right upper quadrant view
From the previous position, the probe is slipped caudally by two intercostal spaces. The liver will be seen with the right kidney posterior to it. This interface between the liver and the kidney is the Morrison's pouch [Figure 4] and is the most dependent area of the upper peritoneum in a supine patient. Free fluid may be seen in the Morrison's pouch [Figure 5] or around the inferior tip of the liver, which is why it is also important to visualize the tip of the liver in this view.
|Figure 5: Right upper quadrant view with fluid visualized in the Morrison's pouch.|
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Left lower thorax view
Similar to the right lower thoracic view, the probe is placed on the left posterior axillary line at the 8th or 9th intercostal space with the dot marker facing headward and then rotated clockwise till it is aligned parallel to the ribs in the intercostal space. A view of the costophrenic angle must be obtained. The spleen will be seen on one-half of the screen and the normal lung on the other half, separated by the diaphragm. Similar to the right, black fluid seen in the costophrenic angle above the diaphragm could represent a hemothorax.
Left upper quadrant view
From the previous position, the probe is slipped caudally by two intercostal spaces along the posterior axillary line. The rotation of the probe aligning it in the intercostal space should be preserved. The spleen will be seen with the kidney posteromedial to it. While free fluid rarely fills the space between the spleen and the kidney, it is often seen over the superior surface and around the tip of the spleen [Figure 6]. It is important to visualize as much perisplenic area as possible.
Subxiphoid four-chamber view
The probe is now placed in the midline 2 cm below the lower end of the xiphoid process with the dot marker to the left of the patient. The probe should be angled toward the left shoulder. Indenting the probe into the abdomen and increasing the depth of the image will both help visualize the heart better. A four-chambered heart will be visible deep to the left lobe of the liver. The right ventricle is seen adjacent to the liver. A pericardial effusion will be seen as a black stripe between the liver and the right ventricle and will often wrap all around the heart [Figure 7].
It is best if both transverse and longitudinal views of the pelvis are obtained.
The probe is placed on the midline just above the pubic bone with the dot marker pointing cephalad. The probe is tilted caudally to visualize the pelvic structures. The bladder will be seen just behind the pubic bone. It is triangular in shape when full. In the male, free fluid may be seen superior [Figure 8] to or posterior to the bladder. In the female, the uterus lies posterior to the bladder and hence free fluid can only be visualized posterior to the uterus in the pouch of Douglas.
|Figure 8: Longitudinal pelvic view with fluid superior to a full bladder.|
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The probe is now turned 90° clockwise. It continues to be tilted to look behind the pubic bone. Free fluid may be seen posterior to the bladder or uterus.
| Interpretation of Extended-Focused Assessment With Sonography for Trauma|| |
E-FAST is most useful in trauma patients who are hemodynamically unstable [Figure 9]. A positive E-FAST examination in such a patient necessitates an emergency laparotomy. In the hemodynamically unstable with a negative E-FAST, it may be prudent to repeat it after 10 min. If a hemodynamically stable patient has a positive E-FAST, a CT of the thorax and abdomen needs to be performed [Figure 10].
|Figure 9: An approach to the management of hemodynamically unstable patients with the focused assessment with sonography for trauma ultrasound.|
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|Figure 10: An approach to the management of hemodynamically stable patients with the focused assessment with sonography for trauma ultrasound.|
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| Pitfalls|| |
- A normal E-FAST, however, does not necessarily exclude significant intra-abdominal injury. Not all abdominal injuries produce detectable free fluid. Bowel perforations and solid organ injuries with contained bleeds will have negative E-FASTs
- Clotted blood could be mistaken for soft tissue
- Free fluid in the pleural, pericardial, and peritoneal spaces needs not always be blood
- Obesity and subcutaneous emphysema obliterate many of the views and reduce the diagnostic ability if the E-FAST
- Ultrasound is an operator dependent skill, and adequate training is required to reduce false positives and negatives.
| Other Uses of Ultrasound in Trauma|| |
Ultrasound-guided vascular access
Central venous and arterial access can be performed under ultrasound guidance. Ultrasound guidance increases success rate on the first puncture, reduces procedural time, and reduces the incidence of complications.
Major trauma in pregnancy carries a high risk for both the mother and fetus. During the primary assessment, ultrasound can rapidly determine the presence of pregnancy, work out the dates of the pregnancy, and determine the fetal heart rate.
Ultrasound-based ABCDE primary survey and head to toes secondary survey
The applications of ultrasound in trauma are vast and increasing every day. A detailed discussion of these is out of the scope of this chapter. [Table 1] and [Table 2] summarize the uses of ultrasound at each step of the primary and secondary surveys.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
| References|| |
Tiling T, Bouillon B, Schmid A. Ultrasound in blunt abdomino-thoracic trauma. In: Border J, Allgoewer M, Hansen S, editors. Blunt MultipleTrauma: Comprehensive Pathophysiology and Care. New York: Marcel Dekker; 1990. p. 415-33.
Scalea TM, Rodriguez A, Chiu WC, Brenneman FD, Fallon WF Jr., Kato K, et al
. Focused assessment with sonography for trauma (FAST): Results from an international consensus conference. J Trauma 1999;46:466-72.
Korner M, Krotz MM, Degenhart C, Pfeifer KJ, Reiser MF, Linsenmaier U. Current Role of Emergency US in Patients with Major Trauma. Radiographics. 2008;28:225-42.
Rozycki GS, Shackford SR. Ultrasound, what every trauma surgeon should know. J Trauma 1996;40:1-4.
Soyuncu S, Cete Y, Bozan H, Kartal M, Akyol AJ. Accuracy of physical and ultrasonographic examinations by emergency physicians for the early diagnosis of intra-abdominal haemorrhage in blunt abdominal trauma. Injury 2007;38:564-9.
Blaivas M, Lyon M, Duggal S. A prospective comparison of supine chest radiography and bedside ultrasound for the diagnosis of traumatic pneumothorax. Acad Emerg Med 2005;12:844-9.
Rozycki GS, Ballard RB, Feliciano DV, Schmidt JA, Pennington SD. Surgeon-performed ultrasound for the assessment of truncal injuries: Lessons learned from 1540 patients. Ann Surg,1998;228:557-67.
Wherrett LJ, Boulanger BR, McLellan BA, Brenneman FD, Rizoli SB, Culhane J, Hamilton P. Hypotension after blunt abdominal trauma: The role of emergent abdominal sonography in surgical triage. J Trauma,1996;41:815-20.
Rozycki GS, Feliciano DV, Ochsner MG, Knudson MM, Hoyt DB, Davis F, et al
. The role of ultrasound in patients with possible penetrating cardiac wounds: A prospective multicenter study. J Trauma 1999;46:543-52.
American Institute of Ultrasound in Medicine, American College of Emergency Physicians. AIUM practice guideline for the performance of the focused assessment with sonography for trauma (FAST) examination. J Ultrasound Med 2014;33:2047-56.
Montoya J, Stawicki SP, Evans DC, Bahner DP, Sparks S, Sharpe RP, et al
. From FAST to E-FAST: An overview of the evolution of ultrasound-based traumatic injury assessment. Eur J Trauma Emerg Surg 2015.
Soult MC, Weireter LJ, Britt RC, Collins JN, Novosel TJ, Reed SF, et al
. Can routine trauma bay chest x-ray be bypassed with an extended focused assessment with sonography for trauma examination?. Am Surg 2015;81:336-40.
Bhoi S, Sinha TP, Ramchandani R, Kurrey L, Galwankar S. To determine the accuracy of focused assessment with sonography for trauma done by nonradiologists and its comparative analysis with radiologists in emergency department of a level 1 trauma center of India. J Emerg Trauma Shock 2013;6:42-6.
Kirkpatrick AW, Sirois M, Laupland KB, Liu D, Rowan K, Ball CG, et al
. Hand-held thoracic sonography for detecting post-traumatic pneumothoraces: The Extended Focused Assessment with Sonography for Trauma (EFAST). J Trauma 2004;57:288-95.
Sheng AY, Dalziel P, Liteplo AS, Fagenholz P, Noble VE. Focused Assessment with Sonography in Trauma and Abdominal Computed Tomography Utilization in Adult Trauma Patients: Trends over the Last Decade. Emerg Med Int 2013;2013:678380.
Fuchs PA, del Junco DJ, Fox EE, Holcomb JB, Rahbar MH, Wade CA, et al
. Purposeful variable selection and stratification to impute missing Focused Assessment with Sonography for Trauma data in trauma research. J Trauma Acute Care Surg 2013;75(1 Suppl 1):S75-81.
Kärk Nielsen S, Ewertsen C, Svendsen LB, Hillingsø JG, Nielsen MB. Focused assessment with sonography for trauma in patients with confirmed liver lesions. Scand J Surg. 2012. 101:287-91.
Barbosa RR, Rowell SE, Fox EE, Holcomb JB, Bulger EM, Phelan HA, et al
. Increasing time to operation is associated with decreased survival in patients with a positive FAST examination requiring emergent laparotomy. J Trauma Acute Care Surg 2013;75(1 Suppl 1):S48-52.
Plummer D, Brunette D, Asinger R, Ruiz E. Emergency department echocardiography improves outcome in penetrating cardiac injury. Ann Emerg Med,1992;21:709-12.
Helling TS, Wilson J, Augustosky K. The utility of focused abdominal ultrasound in blunt abdominal trauma: A reappraisal. Am J Surg 2007;194:728-32.
[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6], [Figure 7], [Figure 8], [Figure 9], [Figure 10]
[Table 1], [Table 2]