Bedside ultrasound in delayed traumatic pericardial effusion

CORRESPONDENCE

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BEDSIDE ULTRASOUNDIN DELAYEDTRAUMATIC PERICARDIALEFFUSION To the Editor:--Penetrating thoracic trauma represents a common injury mechanism seen in urban emergency departments (EDs) and is most frequently the result of either gunshot or stab wounds. Patients presenting in extremis secondary to their chest trauma generally do not pose a diagnostic dilemma for the emergency physician; these patients most often undergo ED thoracotomy. From a diagnostic standpoint, a more challenging group of patients are those with penetrating injuries in anatomically vital areas but without serious signs or symptoms. 1 Depending on the location and mechanism of injury, the diagnosis of pericardial effusion with or without tamponade must be considered. Historically, traumatic pericardial effusion was diagnosed using a combination of physical examination, central venous pressure measurement, diagnostic pericardiocentesis, and thoracotomy. 2 Since the advent of ultrasonography and 2-D echocardiography, the diagnosis of traumatic pericardial effusion and tamponade has improved. Moving this technology to the ED and performing the exam during the secondary survey allows an even more rapid diagnosis of these potentially life-threatening conditions. A previously healthy 21-year-old Hispanic man was brought to the ED by his family, complaining of chest pain and shortness of breath for 2 hours. He also complained of chills without fever and two episodes of syncope prior to arrival. He stated that the pain was getting progressively worse and, at the time of ED evaluation, rated it as severe. The patient had no other complaints. One week earlier, while playing soccer, the patient had fallen against a bench with a protruding nail. Despite a "small" wound on his chest he continued to play without difficulty. He had remained asymptomatic until the day of ED presentation. Physical examination revealed a patient who appeared acutely ill and was in moderate respiratory distress. Vital signs were a temperature of 98.8°17, pulse of 125 beats/min, respirations of 24 breaths/min, and a blood pressure of 108/66 mm Hg. Head and neck exam in the sitting position revealed subcutaneous emphysema at the base of the neck with no jugular venous distension. Lung fields were clear bilaterally and the heart exam, despite tachycardia, revealed normal tones. Inspection of the chest revealed a small healing puncture wound at the fifth intercostal space at the left sternal border. The patient was alert and oriented and the remainder of the examination was noncontributory. ED evaluation included an uptight anteroposterior portable chest radiograph that showed mediastinal and paratracheal air with a normal cardiac silhouette. A 12-lead electrocardiogram showed sinus tachycardia at 121 beats/rain with no electrical alternans. Complete blood count revealed a white blood cell count of 29,700/gL with 82% neutrophils, 11% lymphocytes, 5% monocytes, and 2% eosinophils. The serum glucose level was elevated at 236 mg/dL and a spun hematocrit was 49%. Levels of electrolytes, blood urea nitrogen, and creatinine, as well as the protime, were all normal. Blood was also drawn for a type and cross. Bedside echocardiography performed by the ED physician shortly after the patient's arrival showed a moderate to large circumferential pericardial effusion (Figures 1 and 2). There was no evidence of right ventricular collapse. Trauma surgery consultation was immediately obtained and it was determined that diagnostic and therapeutic pericardiocentesis was necessary. During the patient's ED course, his blood pressure decreased to 87/58 mm Hg despite fluid resuscitation. Cardiology consultation was obtained, and a pericardial catheter was placed under echocardiographic guidance in the ED. Following pericardial drainage the patient's blood pressure increased to 144/86 mm Hg. Pericardiocentesis removed 250 to 300 mL of serosanguinous fluid; cell count revealed many red blood cells, 1,111 nucleated cells with 40%

FIGURE 1. ED ultrasound showing a subcostal view of the right ventricle and the pericardial effusion (arrow). neutrophils, 49% lymphocytes, 4% monocytes, and 6% eosinophils. Gram stain revealed no organisms. Fluid glucose level was 203 mg/dL, total protein level was 6.3 mg/dL, albumen level was 3.5 mg/dL, and lactate level was 3.0 mg/dL. The patient was admitted to the trauma service and placed in the surgical intensive care unit. Triple antibiotic coverage was initiated for a presumptive diagnosis of mediastinitis. Computed tomography (CT) of the chest on hospital day 1 showed no mediastinal abscess or fluid collection. The pericardial catheter drained another 250 mL over the next 24 hours. The catheter was removed on hospital day 5 after a repeat echocardiogram showed no effusion. Blood and pericardial fluid cultures remained negative throughout the hospitalization, although anaerobic cultures were never sent. The patient was discharged home on oral antibiotic therapy with a final diagnosis of mediastinitis with a sympathetic pericardial effusion. Penetrating chest trauma is an increasingly common civilian injury seen in urban trauma centers and EDs. Rapid recognition, resuscitation, and treatment are important because up to 82% of these injuries are fatal. 3 Pericardial tamponade is one result of these

FIGURE 2. ED ultrasound showing parasternal long axis view of the right ventricle, left ventricle, and the pericardial effusion (arrow).

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AMERICAN JOURNAL OF EMERGENCY MEDICINE • Volume 17, Number 3 • May 1999

injuries, but it can be difficult to diagnose in its early stages. Traditionally the mechanism of injury and clinical findings of Beck's triad (distended neck veins, muffled heart tones, and hypotension) raised an appropriate index of suspicion and led to central venous pressure measurements, pericardiocentesis, and, occasionally, subxiphoid pericardiotomy. Unfortunately, the findings of Beck's triad are often not evident, making the physical examination less sensitive for pericardial tamponade. Muffled heart tones may be difficult to appreciate in a busy ED during a trauma resuscitation, and hypovolemia may mask jugular venous distension. Pericardiocentesis and subxiphoid pericardiotomy used as diagnostic tools are fraught with serious complications. Pericardiocentesis is recommended as a temporizing measure and subxiphoid pericardiotomy has resulted in a 50% to 80% negative pericardial exploration rate. 1,4 Central venous pressure measurement in the setting of hypovolemia can result in falsely low values, although serial measurement with fluid resuscitation improves the accuracy. 1 Although the presence of electrical alternans is pathognomic for pericardial effusion, it is seldom present. 5 Chest radiographs may show an enlarged cardiac silhouette, which is nonspecific and more likely to represent a chronic condition. This can also be mimicked in patients unable to sit upright (spinal immobilization) when an anteroposterior supine chest film is taken. Echocardiography is now the primary means of diagnosing pericardial fluid. It is easily and rapidly performed, noninvasive, and recommended in all anterior stab wounds between the nipples.2 Originally echocardiography was performed by cardiologists or echocardiographic technicians called in from home, subjecting the patient to long delays. Bedside ultrasound is currently being performed by emergency physicians for a variety of conditions, including the diagnosis of pericardial effusion. Bedside echocardiogram has been shown to be 97% specific, 96% accurate, and 90% sensitive when performed by surgical residents in detecting hemopericardium. 4 The ability to rapidly diagnose hemopericardium allows definitive care to be given sooner, before the development of tamponade. Plummer et al6 showed that use of immediate bedside echocardiogram resulted in an improvement of nearly 30 minutes in the disposition of patients to the operating room (15.5 min v 42.4 rain). These patients also had a 100% survival rate, whereas those who did not receive immediate bedside echocardiogram had a survival rate reduced to 57.1%.6 The ED ultrasound examination of the trauma patient generally consists of five standard views. Acute, unclotted blood will appear as an anechoic or black stripe on ultrasound. In isolated penetrating injuries to the chest the full set of trauma views is not necessary. There are four standard views used in echocardiography and all are useful in diagnosing pericardial fluid collections. The standard view used as part of the trauma exam is the subcostal view, which uses the liver as a window to achieve a four chamber view. The parasternal views image between the ribs along the left sternal border to examine both long and short axis of the heart. The long axis view visualizes the fight and left ventricles and the left atrium. The short axis view is a cross-sectional view of the right and left ventricles. The apical view utilizes the intercostal space nearest to the point of maximum impulse to visualize all four chambers. Perhaps the best view for diagnosing pericardial effusions is the parasternal long axis. However, this view may be difficult to obtain because of the presence of underlying disease, injury to the patient, or procedures being performed in that area. 7 When pericardial effusion is suspected in one view, it is important to confirm this in at least two views, because the presence of pleural fluid and pericardial fat can interfere with the diagnosis. The presence of pericardial fluid does not equate to pericardial tamponade, though the absence of fluid rules out the diagnosis, 8 Early echocardiographic signs of tamponade are collapse of the right ventricular and right atrial free walls during diastole; these signs precede the clinical findings of Beck's triad. 7

In the case presented there was a significant delay in the patient's presentation. The mechanism behind the development of a delayed effusion is poorly understood because the great majority of these injuries present acutely.9 Theories explaining this involve the dislodgment of an initial thrombus or the formation of an adhesion between the pericardium and the myocardium that later tears. 9 This case may involve the development of a sympathetic or reactive effusion caused by a mediastinitis or direct spread of infection. There are 10 reported cases similar to this in the literature since 1960 involving delays of 3 to 76 days. 2,1°,11 Four of these were diagnosed by echocardiogram performed by cardiologists and no cases were diagnosed via bedside ultrasonography by an ED physician. Although this patient was not diagnosed with tamponade, because of the rapidity of the onset of this patient's symptoms, it is easy to see how a further delay in presentation or a delay in diagnosis could have resulted in more significant morbidity. The placement of a pericardial catheter decompressed the effusion and allowed the trauma surgery team to observe the patient over a period of time. The decision to not take this patient immediately to the operating room was supported by the ultrasound examination and by the minimal drain output following initial decompression with the lack of reaccumulation of the effusion. In 3 of the previous 10 cases similar to ours, thoracotomy demonstrated no cardiac injury.10 This case likely represents a similar situation where the delay in presentation provided an opportunity for a minor cardiac injury to heal. JOHN H. KELSEY,MD

Department of Emergency Medicine LAC + USC Medical Center SEAN O. HENDERSON,MD KIN NEWTON,MD

Department of Emergency Medicine University of Southern California School of Medicine Los Angeles, CA

References 1. Whye D, Barish R, Almquist T, et al: Echocardiographic diagnosis of acute pericardial effusion in penetrating chest trauma. Am J Emerg Med 1988;6:21-23 2. Bolanowski PJP, Swaminathan AP, Neville WE: Aggressive surgical management of penetrating cardiac injuries. J Thorac Cardiovasc Surg 1973;66:52-57 3. Demetriades D, Van der Veen BW: Penetrating injuries of the heart: Experience over two years in South Africa. J Trauma 1983;23: 1034-1041 4. Jimenex E, Martin M, Krukenkamp I, Barrett J: Subxiphoid pericardiotomy versus echocardiography: A prospective evaluation of the diagnosis of occult penetrating cardiac injury. Surgery 1990;1089: 676-680 5. Karrel R, Shaffer MA, Franaszek JB: Emergency diagnosis, resuscitation, and treatment of acute penetrating cardiac trauma. Ann Emerg Med 1982;11:504-517 6. Plummer D, Brunette D, Asinger R, Ruiz E: Emergency department echocardiography improves outcome in penetrating cardiac injury. Ann Emerg Med 1992;21:709-712 7. Snoey ER. Echocardiography. In Simon BC, Snoey ER (eds): Ultrasound in emergency and ambulatory medicine. St Louis, MO, Mosby, 1997, pp 221-249 8. Heller MB, Verdile VP: Ultrasonography in emergency medicine. Emerg Med Clin North Am 1992; 10:27-44 9. Aaland MO, Sherman FIT: Delayed pericardial tamponade in penetrating chest trauma: case report. J Trauma 1991 ;31:1563-1565 10. Mjechem CC, Alam GA: Delayed cardiac tampanade in a patient with penetrating chest trauma. J Emerg Meal 1997;15:31-33 11. Hasegawa J, Noguchi N, Yamasaki J, et al: Delayed cardiac tamponade and hemothorax induce by an acupuncture needle. Cardiology 1991 ;78:58-63