CASE CONFERENCE Mark A. Chaney, MD Victor C. Baum, MD Section Editors

CASE 6—2015 Penetrating Biventricular Cardiac Injury in a Trauma Patient: Heart Versus Machete Christian Diez, MD, MBA, Bianca Conti, MD, Maureen McCunn, MD, MIPP, FCCM, Michel B. Aboutanos, MD, MPH, and Albert J. Varon, MD, MHPE, FCCM

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NJURIES TO THE HEART and great vessels can occur by almost any mechanism in patients who have sustained trauma. These injuries can be categorized into injuries that are so devastating that patients die at the scene and injuries that are stable enough for patients to arrive at the hospital. In the hospital setting, several factors affect the management of patients who sustain cardiac or great vessel injuries, including the mechanism of injury (penetrating v blunt), patient stability (unstable v stable), and injury location (cardiac v great vessels). When a patient presents with an obvious cardiac injury, the anesthesiology team should be prepared to initiate several key interventions immediately. These interventions include airway management, obtaining intravenous access, and determining which patients are candidates for extreme lifesaving maneuvers. The anesthetic management in the operating room (OR) includes supporting the circulation, providing maneuvers that aid surgical repair, and identifying the extent of cardiac injury. Postoperatively, it is important to ensure adequate resuscitation and continue close monitoring. The following case highlights various issues that need to be considered when managing a patient who presents with a significant cardiac injury. CASE REPORT

A 31-year-old man (height 175 cm, weight 77 kg) was brought to the trauma center after sustaining stab wounds with a machete. One wound was to the left shoulder, and a second wound was to the left anterior chest. He arrived without vital signs and receiving cardiopulmonary resuscitation (CPR). The total time without vital signs was reported by prehospital personnel to be o10 minutes. The patient underwent immediate tracheal intubation, intravenous access was obtained, and an anterolateral resuscitative thoracotomy was performed in the emergency department (ED). Because of cardiac tamponade, a decision was made to open the pericardium. A large amount of blood clot was evacuated from the pericardial space. Two large lacerations were identified involving both left and right ventricles. These lacerations were closed emergently with staples. After continued CPR and administration of crystalloids and blood, the heart began exhibiting unorganized electrical activity. The heart was defibrillated with internal paddles, and organized cardiac activity was obtained. The patient was rushed to the OR. In the OR, the patient was placed in the supine position. A 9F central venous catheter was inserted in the right internal

jugular vein. A right radial arterial catheter also was placed. The trauma center’s massive transfusion protocol was initiated, and the patient’s intravenous access was connected to a rapid infusion device. Scopolamine, 0.4 mg, rocuronium, 80 mg, fentanyl, 250 μg (in divided doses), and cefazolin, 2 g, were administered. Sevoflurane was used for anesthetic maintenance as tolerated by the patient’s blood pressure. Careful attention was given to avoid large fluctuations in blood pressure because of concern that severe hypertension would increase bleeding or disrupt the initial repair. The goal was to maintain the patient’s systolic blood pressure (SBP) at 80 to 90 mmHg. An initial dose of epinephrine, 100 μg, was administered owing to severe hypotension. After incision, a median sternotomy was performed, and the pericardium was reopened. The laceration at the apex of the right ventricle, which had been closed temporarily with staples, was oversewn with a 3-0 polypropylene (Prolene) suture and pledgets in a running fashion. The injury to the left ventricle was repaired in a similar fashion via the anterolateral thoracotomy wound. When the cardiac injuries were closed, a left lung injury was sutured, and bleeding was controlled. Two left-sided chest tubes, one right-sided chest tube, and a mediastinal chest tube were placed, and the sternotomy was closed with sternal wires. Skin incisions were closed with staples. The patient’s initial pH and base excess in the OR were 6.8 and
16.5, respectively. Fluid totals for the case were 8 L of crystalloid, 17 units of packed red blood cells, 7 units of fresh frozen plasma, and 10 units of platelets. The estimated blood loss was 8,500 mL, and urine output was 405 mL. On leaving the OR, the pH was 7.3, and base excess was
5.9. The patient was transported intubated to the trauma intensive care unit

From the Department of Clinical Anesthesiology, Division of Trauma Anesthesiology, Ryder Trauma Center–Jackson Memorial Hospital, University of Miami Miller School of Medicine, Miami, FL. Address reprint requests to Christian Diez, MD, MBA, Division of Trauma Anesthesiology, Ryder Trauma Center–Jackson Memorial Hospital (T-243), University of Miami Miller School of Medicine, 1800 NW 10th Avenue, Miami, FL 33136. E-mail: [email protected] © 2015 Elsevier Inc. All rights reserved. 1053-0770/2602-0033$36.00/0 http://dx.doi.org/10.1053/j.jvca.2015.01.017 Key words: trauma, penetrating cardiac injury, trauma anesthesia, hemorrhage, thoracotomy, emergencies

Journal of Cardiothoracic and Vascular Anesthesia, Vol 29, No 3 (June), 2015: pp 797–805

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(TICU) for further resuscitation. Vital signs on TICU admission were pulse 164 beats/min, blood pressure 97/57 mmHg, oxygen saturation 92% (FIO2 ¼ 1), and temperature 37.21C. During the first 90 minutes after TICU admission, the patient’s chest tube drained 42 L of blood. A decision was made to take the patient back to the OR for re-exploration. The patient required several boluses of epinephrine on arrival in the OR to maintain blood pressure. After the sternotomy wound was reopened, an anomalous vein producing major blood loss was repaired. Because the left chest tubes were noted to have increased output, the left thoracotomy incision also was reopened. The right atrium and ventricle were noted to be dark, engorged, and in apparent failure. Bleeding from a prior left ventricular repair site also was observed. During re-exploration, the left ventricle ruptured, leading to massive blood loss. The surgical team approximated the left ventricular edges using staples, Prolene suture, and pledgets in an interrupted fashion. An intraoperative cardiothoracic surgery consultation was requested. The cardiothoracic surgeon agreed with surgical repair. After ventricular repair, massive transfusion, and dobutamine infusion, the right side and overall cardiac function improved. A decision was made to close most of the incision, but an area immediately over the heart was covered with Gore-Tex (W.L. Gore & Associates, Inc, Newark, DE) to prevent any immediate pressure on the heart that would impede function. Chest tubes were replaced. Fluid resuscitation included 6 L of crystalloid, 17 units of packed red blood cells, 12 units of fresh frozen plasma, 10 units of platelets, and 1 dose of cryoprecipitate. The patient was transported to the TICU on a dobutamine infusion of 2.5 μg/kg/min. During the immediate postoperative period, the patient opened his eyes but did not follow commands while receiving sedation. Dobutamine and norepinephrine were administered to maintain blood pressure. On postoperative day 1, his pupils became dilated and unreactive. Transesophageal echocardiography (TEE) revealed a dilated right ventricle with poor contractility, good left ventricular function, but no valvular abnormalities (Fig 1). Computed tomography scan of the brain demonstrated diffuse edema with signs of anoxic brain injury. The patient remained on vasopressors and developed increased blood urea nitrogen and creatinine. Over the next 6 days, blood

Fig 1. View of dilated right ventricle, which revealed poor contractility.

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pressure was maintained with vasopressors, antibiotics were started for fever, and hemodialysis was initiated. Neurologic status remained unchanged. On postoperative day 8, the patient was posturing and had nonpurposeful movements in response to pain. The patient was taken to the OR for closure of the thoracotomy incision and placement of a sternal wound vacuum. Over the next 2 weeks, the patient’s cardiac function improved, and he eventually was weaned off vasopressors. However, he continued to require dialysis and mechanical ventilation. Neurologic status was deemed irrecoverable, and the family requested to withdraw support on postoperative day 25. DISCUSSION

In the United States, trauma is the third leading cause of death in people of all ages (following heart disease and cancer) and is the leading cause of death in children and adults up to 44 years of age.1 Overall, motor vehicle accidents are the number 1 cause of fatalities owing to injury.1 Firearm-related fatalities are the second leading cause of injury-related deaths. Cardiac injury of varying degrees can be found in many trauma patients, from a small cardiac contusion that is never diagnosed to life-threatening injuries. Cardiac injuries can be categorized into blunt or penetrating. Blunt cardiac injuries commonly are associated with injuries to great vessels or other organs and may be difficult to detect expeditiously when multiple organs are affected. Penetrating cardiac injuries may be easier to identify quickly because fewer organ systems may be involved. While obtaining the patient’s history (often provided by prehospital personnel only) and adhering to advanced trauma life support (ATLS) protocol, clinicians must develop a plan guided by possible injuries to be encountered. The present case involved a patient with penetrating chest injury who arrived at the hospital receiving CPR. Certain actions such as ED thoracotomy, expeditious damage control, and maintenance of hemodynamic function allowed this patient to survive his injuries initially. One of the first decisions to make on the arrival of a severely wounded trauma patient is the appropriateness of an ED thoracotomy. The current ATLS guidelines delineate criteria and suggestions of when a resuscitative ED thoracotomy should be performed.2 The ATLS guidelines list the following as indications for ED thoracotomy: (1) evacuation of pericardial blood causing tamponade; (2) direct control of exsanguinating intrathoracic hemorrhage; (3) open cardiac massage; (4) crossclamping of the descending aorta to slow blood loss below the diaphragm and increase perfusion to the brain and heart Even when performed for proper indications, the success rate of ED thoracotomy is not high. Patient selection is of utmost importance. The ATLS guidelines state that patients who sustain blunt injury and arrive without a pulse are not candidates for ED thoracotomy2; this includes patients with pulseless electrical activity after blunt injury. In contrast, patients who are receiving CPR after penetrating injury should be evaluated for “signs of life.” The “signs of life” are reactive pupils, organized electrical cardiac activity, or spontaneous movement.2 If any of these signs is present, patients may be candidates for ED thoracotomy.2 Reducing the number of ED thoracotomies may reduce exposure of healthcare providers to incidental injuries or

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transmission of disease. Aihara et al3 modified their ED thoracotomy policy into a protocol with qualifying and disqualifying criteria. Although some deviations from the protocol occurred, these authors decreased their ED thoracotomy rate and increased their success rate. Half of the patients who arrived with vital signs and received an ED thoracotomy survived, as opposed to none of the patients who arrived without vital signs after sustaining penetrating injury. One caveat with the aforementioned study is that the protocol listed tamponade as the only indication for ED thoracotomy. As noted earlier, the ATLS guidelines list indications in addition to relief of tamponade. Factors such as mechanism of injury, CPR duration, and signs of life should be considered when developing algorithms for ED thoracotomy.4 Anesthesiologists often are asked to assist in the decision-making process to abort or discontinue lifesaving efforts. Familiarity with the indications for ED thoracotomy facilitates more effective participation in this process. The intraoperative anesthetic management of patients with penetrating cardiac injury varies according to the severity and location of the injury, the patient’s condition on arrival in the OR, and available resources. Penetrating cardiac injuries most commonly occur from knives or gunshot wounds.5 However, these injuries also can result from a wide variety of sources, including rib or sternal fractures, wire, fence posts, and sporting equipment.5 The site or extent of injury may not be apparent from surface wounds. Injuries occur most commonly in the anterior right ventricle, followed by the left ventricle. The muscular left ventricle occasionally can seal off minor or lowvelocity penetrations better than the thinner right ventricle. Right atrial penetrating injuries also are more common than the posteriorly placed left atrium.6 Tears and contusions are more common with blunt injuries than with penetrating injuries. In the present case, the immediate temporary control of injuries and bleeding occurred during an ED thoracotomy, followed by immediate operative treatment. The focused assessment with sonography for trauma (FAST) examination includes a subxiphoid pericardial view for evaluation of fluid around the heart. There are several considerations when a patient is brought to the OR for a positive FAST examination after sustaining a penetrating cardiac injury. If the patient is unstable, drainage of the pericardial sac may have to be performed under local anesthesia. When enough fluid is drained from the pericardium, general anesthesia can be induced for surgical repair. When immediate pericardial drainage is not required, general anesthesia can be induced before therapeutic intervention. Ideally, the patient should be prepared and draped in the OR before induction of anesthesia; this allows for rapid drainage and alleviation of pericardial sac pressure when anesthesia is induced. An arterial catheter should be placed before induction to monitor the blood pressure closely during induction and determine if the hemodynamics improve when the pericardial sac pressure is relieved. Although various medications can be used to induce general anesthesia, several issues must be considered. The patient’s heart rate and systemic vascular resistance should not be decreased because cardiac output becomes rate dependent. Ketamine can serve as a valuable medication in such a scenario. Allowing the patient to breathe spontaneously, when possible, helps maintain

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cardiac filling; this can be achieved with lower doses of ketamine or inhaled anesthetics and absence of neuromuscular blocking drugs. Securing the airway may be possible with the aforementioned medications. However, muscle relaxation may be needed to facilitate tracheal intubation or ventilation. In such cases, administering a reduced dose of an induction agent and a fast-acting neuromuscular blocking drug after the patient is prepared and draped and with advanced monitors in place can prove most beneficial. Pericardial pressure should be relieved as soon as possible. Special attention should be given to the size of tidal volume administered if mechanical ventilation is initiated before drainage of pericardial tamponade. Large tidal volumes may decrease cardiac output and result in cardiovascular collapse. In a randomized controlled trial, Nicol et al7 studied stable patients (after 24 hours) with hemopericardium confirmed by a subxiphoid pericardial window and no active bleeding after penetrating trauma. The investigators randomly assigned 55 patients to be managed with sternotomy and 56 to be managed with pericardial drainage alone. Nicol et al7 reported pericardial drainage to be as safe and effective as sternotomy. During repair of the myocardium, several anesthetic interventions can facilitate surgical exposure. First, maintaining an SBP of 80 to 90 mmHg (“hypotensive resuscitation”) can decrease blood loss and blood on the field as the surgeon attempts to suture the heart.8 Bickell et al9 reported that maintaining an SBP r90 mmHg improved outcome in patients with penetrating torso injuries. Dutton et al10 found no difference in mortality when an SBP of 70 mmHg was maintained in trauma patients compared with an SBP 4100 mmHg in a control group. In preliminary results of a randomized controlled trial, Morrison et al11 found no significant difference in 30-day mortality in patients randomly assigned to a mean arterial pressure of 50 mmHg versus 65 mmHg. However, age 445 years, suspected or documented head injury, and known cardiovascular history were some of the exclusion criteria. Clinicians should take into consideration other injuries (eg, head trauma), age, and medical history when considering such blood pressure targets in patients with penetrating cardiac injury. Intravenous adenosine may be used to stop myocardial contraction temporarily ( 20 seconds) and provide the surgeon a motionless operating field briefly.12 Careful coordination and communication between the surgeon and the anesthesiologist allow for adenosine to be given when the surgeon is ready to repair the injury and maximize the time to work on a nonbeating heart. Significant injuries may require cardiopulmonary bypass for surgical repair. However, factors such as associated injuries, risks of heparinization, and the time required for preparation may limit this option to only a few cases. Prophylactic medications for arrhythmias are not indicated, but arrhythmias are treated if and when they occur.5 The use of echocardiography can facilitate greatly the preoperative, intraoperative, and postoperative management of patients with penetrating cardiac trauma. The subxiphoid cardiac component of the FAST examination, when performed by surgeons, has been demonstrated to be very useful in patients presenting with cardiac injury.13,14 In addition to the FAST examination, limited transthoracic echocardiography (LTTE) now is being used in trauma bays.15 LTTE has been

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shown to be useful in hypotensive patients for assessing cardiac contractility, fluid status (via the inferior vena cava), and presence of pericardial effusion.15 In contrast to TEE, clinicians can become fairly proficient in performing LTTE with minimal training.16 If time permits, formal transthoracic echocardiography (TTE) also can help identify injuries and assess heart function.17 In blunt injuries, TEE has been shown to be as reliable as computed tomography for identification of acute aortic injuries.18 TEE has the added benefit of being able to diagnose associated cardiac injuries.18 The performance of formal TTE or TEE is reserved for patients who are stable enough to undergo such examinations preoperatively. If the clinician is proficient in both modalities, TEE may be preferable in (1) hemodynamically unstable patients with suboptimal TTE images, (2) mechanically ventilated hemodynamically unstable patients, (3) patients with major trauma or postoperative patients unable to be positioned for adequate TTE, and (4) patients with suspected aortic dissection or aortic injury.19 When a patient arrives in the OR after a penetrating cardiac injury, he or she may be stable or in extremis. In situations in which patients are in extremis and multiple tasks need to be accomplished, it may be difficult to perform intraoperative TEE immediately. However, when the patient is stabilized, TEE can be an invaluable tool to address multiple concerns. These concerns include valvular malfunction either from the initial injury or secondary to poor function initiated by the injury. When possible, myocardial function should be monitored during cardiac repair. Accidental coronary artery involvement during suturing can be assessed indirectly by an acute deterioration in function, providing valuable information. TEE also can assist during resuscitation and in assessing effectiveness of inotropic support intraoperatively and postoperatively. Risks of TEE probe insertion include dental, pharyngeal, and esophageal trauma.19 TEE probes should not be inserted into patients with known or suspected esophageal injuries. This possibility should be taken into consideration in cases of deep knife injuries and transmediastinal gunshot wounds. During the postoperative period, echocardiography may continue to provide valuable information on the efficacy of repair, hemodynamic condition, and long-term follow-up. Castano et al20 found that 30% of patients who presented with penetrating cardiac trauma experienced a post-traumatic acute myocardial infarction (PAMI). These myocardial infarctions were divided further into PAMI with coronary injury and PAMI without coronary injury. The incidence of PAMI without coronary injury is almost double that of PAMI with coronary involvement. The findings of the study by Castano et al20 stressed the important of continued follow-up of patients who sustain penetrating cardiac injuries. CONCLUSIONS

Penetrating cardiac injuries can vary greatly on presentation. They can range from small injuries that can close off spontaneously to biventricular rupture. The mechanism of injury, presence and duration of CPR, and signs of life can help determine when extreme lifesaving measures should be initiated. Intraoperative considerations include how and when to induce general anesthesia in these patients. Techniques such as

controlled hypotension or temporary asystole can aid in providing a workable surgical field. Lastly, the role of echocardiography continues to expand from intraoperative use to use for diagnosis and treatment in trauma patients. COMMENTARY 1*

The resuscitation of a trauma patient begins before arrival at a trauma center. Prehospital care can be as important as what happens after the patient is admitted and can affect outcome just as substantially. Many variables exist outside of the designated trauma center; many are contingent on where the patient is injured. Depending on jurisdiction and local practices, patients may be intubated before arrival, or the prehospital providers may institute mask ventilation in addition to CPR. Changes in adult cardiac life support and basic life support have advocated minimizing interruptions in chest compressions, maintaining a perfusing pressure throughout CPR. When paramedics and other prehospital personnel take time to perform endotracheal intubation in patients in arrest in the field, there is considerable interruption in CPR21; however, placement of an advanced airway can facilitate oxygen to vital organs, and chest compressions and ventilation can be performed simultaneously. However, in a patient in hemorrhagic shock, the primary goal is to stop the hemorrhage. After arrival to the trauma center, the patient in the present report was intubated emergently, resuscitative lines were placed, and a FAST examination was performed quickly in the trauma bay. With anesthesiologists as part of the admitting trauma team, many of these actions occur simultaneously and in concert with one another. The entire team can focus on ATLS and move quickly to determine the cause of the trauma and the appropriate management of the patient. With the anesthesiologist in the trauma bay at admission, the airway can be secured quickly, vital sign monitors can be applied, appropriate intravenous and arterial lines can be accessed and used, resuscitation with massive transfusion by the anesthesiologist is facilitated, and the OR personnel are acutely aware of the plan of treatment so there is minimal delay or hand-offs when emergent OR care is needed for definitive treatment. A patient after cardiac trauma often does not proceed to the OR without a return of signs of life. The initial treatment for a patient in arrest is an anterolateral ED thoracotomy. The purpose of the resuscitative thoracotomy is to achieve internal cardiac massage, internal cardiac defibrillation, evacuation of pericardial tamponade, and direct control of thoracic hemorrhage, and the thoracotomy affords the opportunity to crossclamp the descending aorta directly above the diaphragm to increase preload in a hypovolemic patient and increase perfusion to the coronary and cerebral circulations or decrease bleeding below the clamp. The American College of Surgeons Committee on Trauma concluded that an anterolateral ED resuscitative thoracotomy does not have a role in prehospital traumatic cardiopulmonary arrest as a result of blunt trauma. In 2004, a study of 4900 patients found that resuscitative thoracotomy is futile in patients with penetrating trauma

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M. McCunn and B. Conti

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with 415 minutes of prehospital CPR,22 and patients with blunt injury had uniformly dismal neurologic outcomes.23 Other factors predicting poor outcome include arrival to the ED without signs of life and failure of SBP to rise above 70 mmHg in response to aortic occlusion.24 A potential alternative to resuscitative ED thoracotomy, or an option when aortic cross-clamping is difficult, is resuscitative endovascular balloon occlusion of the aorta (REBOA). Comparing open thoracotomy with aortic clamp occlusion versus REBOA in an animal model, the endovascular technique resulted in greater increases in central perfusion pressures with less physiologic disturbance.25 Many institutions do not perform resuscitative thoracotomy in patients with blunt trauma; however, a small clinical series comprised of patients with blunt trauma and patients with penetrating trauma showed REBOA to be an effective means of proactive aortic control for patients in endstage shock (Figs 2 and 3). There were no REBOA-related complications and no hemorrhage-related mortality, and mean SBP increased by 55 mmHg.26 After the return of signs of life, patient care often is transitioned to the OR. In the OR, the anesthetic management is to continue resuscitation that occurred in the prehospital setting and the trauma bay. Care can include the initiation of a massive transfusion protocol with the goal of permissive hypotension to maintain an SBP of 80 to 90 mmHg and avoidance of large swings in blood pressure. A ratio of 1 unit of packed red blood cells to 1 unit of fresh frozen plasma and 1 unit of platelets has been shown to decrease coagulopathy in patients with massive transfusions.27 Although early studies in military and civilian cohorts suggested a survival benefit, it is unclear if the targeted hypotension intended to decrease blood loss until hemorrhage control, the “whole” blood transfusion, or some other variable is associated with decreased mortality. It is also imperative to attempt to keep the patient warm, as the anesthesiologist did in the present case. Body heat, generated as a result of oxygen consumption, decreases as the patient’s oxygen consumption is decreased as a result of shock secondary to trauma. Hypothermia, acidosis, and coagulopathy comprise the lethal triad of trauma. Hypothermia contributes to coagulopathy by inhibiting the enzymatic reactions of the coagulation cascade, resulting in prolonged clotting time similar to that seen in patients with severe factor deficiencies. A core temperature o321C in trauma patients is

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associated with 100% mortality, and any decrease in temperature to o351C is a poor prognostic sign.28 Patients who are not rewarmed aggressively have a 7-fold increase in mortality.29 There are multiple techniques to attempt to rewarm and to prevent cooling of a trauma patient. Forced air warmers and circulating surface water warmers are fairly ineffective in warming and preventing heat loss at the core of the patient. The challenge in trauma patients who are hemorrhaging is amplified because of the amount of surface area (the entire body in the trauma bay) exposed to cold temperatures, the frequent presence of blood covering the skin that further contributes to inadvertent cooling, massive infusions of fluids —despite warmers—and often resuscitation that occurs in an angiography suite without attention paid to warming the environment. Warmed intravenous fluids and blood products are more effective than surface warmers. Pleural and peritoneal lavage with warm fluids also directly warms the core of the patient. Other extreme techniques that have been used to increase the core temperature of the patient include cardiopulmonary bypass and continuous arteriovenous rewarming, which is analogous to hemofiltration, usually via access in the femoral artery and vein.30 Some anesthesiologists also are able to assist in resuscitation with the help of TEE. Although the FAST examination can be accomplished quickly in the trauma bay, TEE can be extremely specific for identifying cardiac injuries and determining volume status. The performance of TEE often is reserved for the sickest and most unstable patients to identify reasons for, and ways to correct, the instability. Absolute contraindications to the placement of the TEE probe include recent esophageal surgery, a history of dysphagia, and pathologies of the esophagus; however, unstable trauma patients often are unable to give pertinent information. Cervical spine injury is noted to be a relative contraindication to the placement of a TEE probe; however, this does not have to preclude placement if the risks of determining injury outweigh the risks of placement. Especially in patients with a thoracic injury, TEE can be useful in the trauma bays, in the OR, and postoperatively. Initial assessment can identify the injured area to guide surgeons to surgical repair. Intraoperative TEE can show progression of the extent of the injury; for example, an injury to the left anterior descending coronary artery manifesting as left ventricular anterior dysfunction given that the left anterior descending

Fig 2. REBOA in zone III ready for transport to definitive care (interventional radiology or OR). (© 2013 University of Maryland, Baltimore, courtesy of Dr. M.L. Brenner.)

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Fig 3. Radiograph demonstrating severe pelvic fractures and REBOA in zone III.

coronary artery is the main supplier of the left ventricle, and compromise would result in the demise of the heart muscle. TEE also can be useful in locating foreign bodies, such as bullets, and determining the trajectory of the penetrating object by following the destruction path, whether limited to one side or crossing the septum—elicited by seeing a Doppler jet from the higher pressure left side through to the right side. The modality also is used in the intensive care unit to evaluate hypotensive causes such as dysfunction or hypovolemia, which guides treatment such as pressors or intravenous fluid. In the present case, TEE revealed a dilated right ventricle with poor contractility with preserved left ventricular function and no valvular abnormalities. Pulmonary hypertension can cause isolated right ventricular failure and dilation; however, when dysfunction is seen, the pulmonary hypertension is usually significant enough to have associated valvular dysfunction. Causes of pulmonary hypertension include hypoxia, possibly during initial transport to the trauma center; acute respiratory distress syndrome and acute lung injury, possibly after the large amount of transfused products the patient received; and pulmonary embolism after trauma. Diagnosis of pulmonary hypertension with TEE uses Doppler through a tricuspid regurgitant jet. In the absence of obstruction to right ventricular outflow, peak velocity of the jet allows calculation of the pressure gradient between the right ventricle and atrium and provides an estimate of pulmonary artery systolic pressure. The equation used in this technique is PAS ¼ 4(VTR)2 þ CVP, in which PSA is the pulmonary artery systolic pressure, VTR is the velocity of the regurgitant jet across the tricuspid valve, and CVP is the central venous pressure.

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Another cause of the TEE findings in the present patient could be occult initial injury to the right coronary artery causing isolated right ventricular failure and dilation. Although the anteriorly placed left anterior descending coronary artery is most frequently injured in penetrating trauma, the right coronary artery, which provides perfusion to most of the right ventricle, is the second most commonly injured vessel.31 This injury can manifest as right ventricular failure with preserved systolic function. Qualitative assessment includes visualization of right ventricular end-diastolic and end-systolic areas. A measure of Doppler cardiac output from the right ventricular outflow tract correlates with right ventricular function. Hepatic vein flow patterns can be used similarly to pulmonary vein flow in the evaluation of left ventricular function. Alteration of the normal flow includes obliteration of hepatic vein systolic inflow peak and retrograde systolic flow.32 Closure of the thorax after the second surgery was done in part with Gore-Tex in an effort to prevent thoracic compartment syndrome, a phenomenon that occurs after massive resuscitation.13 Full approximation of ribs and sternum may result in severe hypotension in a patient with cardiac dysfunction. Even in patients with good cardiac function, approximation of the sternum and ribs causes an increase in restriction to diastolic filling and a decrease in cardiac output.33 TEE can be extremely useful by noting the cardiac function with the chest open and noting decreases in filling and function with corresponding hypotension when closing commences. TEE is useful in confirming this diagnosis. From the initial injury, several factors affect the outcome in trauma patients, beginning with the prehospital management, including effective CPR and efficient delivery to a hospital for more definitive care. In the trauma bay, patients may undergo anterolateral ED resuscitative thoracotomy or REBOA depending on presenting symptoms of the patient and comfort of the physicians with the techniques. Anesthesiologists play a critical role in the trauma bay, ensuring a stable airway, establishing vascular access, guiding resuscitation, facilitating transit to the OR, and deciding when further treatment is futile in consultation with surgical colleagues. In the OR, surgical control of bleeding is attempted while the anesthesiology team maintains euvolemia, normothermia, and permissive hypotension. Modalities to assist in these goals include various techniques to warm the patient, a ratio of 1 unit of packed red blood cells to 1 unit of fresh frozen plasma and 1 unit of platelets, and TEE. As the present case demonstrates, using all of these techniques does not guarantee survival; however, trauma care continues to evolve, and patient survival continues to increase. COMMENTARY 2†

From a trauma surgery standpoint, penetrating and blunt cardiac injuries are among the most challenging cases to manage clinically and surgically. The case presented by the authors delineates well the various nuances and pitfalls of cardiac trauma management. Until the early 1900s, cardiac injury, especially penetrating injury, was considered fatal.34,35

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M.B. Aboutanos

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At the present time, as a result of significant developments in trauma and emergency medical systems, with training and coordinated communication and response both at the scene and during transport, more patients with severe cardiac injuries are reaching the hospital alive.36 At the hospital, improvement in diagnostic capabilities, multidisciplinary team response, and improved surgical and anesthetic response lead to 450% survival rates in many places.37 Hemodynamic stability on admission and low-energy wounds such as stab wounds are associated with improved survival.37 The presence of cardiac tamponade has been associated with mixed and conflicting survival benefit, most likely secondary to the time of detection and relief of cardiac compression.37–40 The 2 most common presentations of penetrating cardiac injury are pericardial tamponade and hemorrhagic shock. Cardiac tamponade can manifest acutely or develop gradually and requires a high index of suspicion and careful monitoring and follow-up. This is particularly important in a polytrauma patient with various associated and distracting injuries. On presentation, any penetrating injury to the thorax in the “cardiac box” denotes proximity to the heart and is associated with 10% to 20% of cardiac injuries.41 The cardiac box is defined as an area inferior to the clavicles, superior to the costal margin, and medial to the midclavicular lines. Definitive exclusion of a cardiac injury using various modalities such as ultrasound or pericardial window is important. At the present time, the use of pericardiocentesis in the setting of trauma for the diagnosis and treatment of pericardial injury is extremely limited and has been abandoned by most trauma centers because of its high false-negative and false-positive rates and the risk of injury to the heart. Apart from having a high index of suspicion for development of cardiac tamponade based on the mechanism of injury and the report from first responders (emergency medical services [EMS]), there are other specific clinical features, including tachycardia, narrow pulse pressure, and decrease in blood pressure. The presence of distended neck veins, hypotension, and muffled heart sounds representing Beck’s triad are present o10% of the time. Distended neck veins may not be present in the face of profound hypotension, and muffled heart sounds are extremely difficult to detect in the chaotic trauma bay.42,43 Other signs include pulsus paradoxus, pericardial friction rub, and Kussmaul sign (an increase in central venous pressure during inspiration). Overall, the physical examination is unreliable, especially in a polytrauma patient with head injury or under the influence of alcohol and drugs. For this reason, the FAST examination with a quick and accurate ability to detect pericardial fluid has become the diagnostic tool of choice for pericardial effusions and suspected cardiac injuries. With adequate training of the clinician, the FAST examination can achieve an accuracy of 97% to 100% in detecting cardiac injuries.13,44 Trauma surgeons and emergency physicians additionally have expanded their armamentarium to include LTTE, allowing a more rapid, detailed, and accurate diagnosis of cardiac injuries including the evaluation of cardiac contractility and fluid status and detection of pericardial effusion.16 Sonographic signs of cardiac tamponade include the collapse of the various cardiac chambers, especially the atria, a plethoric inferior vena cava, inspiratory expansion of

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the right ventricle, and simultaneous compression of the left ventricle and reciprocal changes in the expiratory phase.45 Even with the demonstrable usefulness and accuracy of ultrasound in penetrating cardiac trauma, a high level of suspicion should be maintained for a negative pericardial FAST examination in the face of traumatic injury in the cardiac box, signs of hypovolemia, and pleural effusion. A caveat to the performance of pericardial ultrasound in patients with penetrating cardiac wounds is the presence of concurrent lacerations of the pericardial sac; a pericardial ultrasound scan may not detect a cardiac injury because of associated decompression into the thoracic cavity.46 The most important aspect in the recognition and management of cardiac injury is communication at all levels. Communication between the EMS and trauma team in the trauma bay is vital. A patient presenting in obstructive shock usually is sitting up on the stretcher, with EMS personnel reporting that the patient refuses to lie back. A mistake by the trauma team is to disregard the patient’s sense of impending doom or the EMS report and to make the patient lie flat; this usually is followed by a decrease in blood pressure and a traumatic cardiac arrest. There are specific cases in trauma that include obstructive shock (tension pneumothorax, cardiac tamponade) or mechanical obstructive injuries such as bilateral mandibular fractures in which the tongue loses its structural support and falls back, obstructing the airway in which a patient presents to the ED on the stretcher in a sitting position. In obstructive shock, a sudden decrease in cardiac output is caused by impediment of diastolic filling of the ventricles. In cardiac tamponade in particular, the rapid accumulation of blood in the pericardial space compresses the heart and prevents diastolic filling; this is accentuated as the patient lies back, causing additional compression on the thin-walled atria and leading to decrease in venous return and reduction in cardiac output. Listening to the patient or the EMS personnel is lifesaving, especially if a mechanism of penetrating thoracic or thoracoabdominal injuries is present. In the ED, a patient with a decrease in blood pressure with impending cardiac arrest and positive FAST examination requires resuscitative lateral thoracotomy; opening of the pericardium to alleviate tamponade; and temporary control of myocardial bleeding that includes attempts at suture placement, use of a stapler as described by the authors of the present case, and use of a balloon catheter, which is not always successful and may lead to widening of the myocardial injury. Atrial injuries are usually easily controlled with the use of a vascular clamp until definitive operative control. The success of such maneuvers in the ED depends on the availability of resources and prior preparation and team rehearsal or significant experience as usually develops in busy urban settings. Similarly, as alluded to by the authors of the present case, communication among the trauma team, the surgeon in particular, and the anesthesia team is equally important and vital to the patient’s survival and management of comorbidities. A patient with suspicion for cardiac tamponade or with a pericardial fluid accumulation confirmed by ultrasound should not be made to lie back in the OR, and anesthetic induction should be delayed until the patient is prepared and draped in the sitting position and the operative team is scrubbed and ready. Failure to do so would result in decrease in blood

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pressure or cardiac arrest and lead to a frantic response to intubate and protect the patient’s airway; restore circulatory volume; and, most importantly, relieve the tamponade via an emergent resuscitative lateral thoracotomy. Such lack of understanding and inadequate communication between the surgical and anesthesia teams can lead to circulatory collapse and significant complications, including cerebral anoxia and an increase in postoperative comorbidities, especially thoracic wall wound infections and empyema. Communication with the entire operating team is also extremely important, with the surgeon communicating to the scrub nurse and circulating staff the need to prepare the patient in the sitting position quickly and be prepared for a potential cardiac arrest when anesthesia is induced and the patient is laid flat. This can be a stressful situation, but it can be managed well given adequate anticipation and preparation by the entire OR team. Similarly, anticipation of blood loss should trigger the activation of the massive transfusion protocol and the notification of the blood bank of impending need of delivery of blood products, which is currently in a 1:1:1 ratio. After anesthesia is induced and the airway is controlled, communication between the operative surgeons and the anesthesia team continues to be vital. When the injury is identified, control of the injury again requires explicit back-and-forth communication between the surgical team and the anesthesia team. This communication becomes vital when dealing with a posterior injury that requires elevating the heart to gain access to the injured site. Such a maneuver causes a sudden impedance in venous return and decrease in blood pressure, bradycardia, and possible cardiac arrest. Preloading the patient before such maneuvers is important, along with a gradual elevation of the heart, if feasible, with a warm moist towel or gauze packs to minimize the acute physiologic insult. The trauma surgeon too often finds it challenging to repair a posterior injury adequately in the face of active hemorrhage

and compensatory cardiac tachycardia with a moving myocardium. The anesthesia team can be asked to start an adenosine infusion, which leads to temporary asystole, allowing the surgeon more accurate and secure placement of the suture. This technique also is useful during the repair of a laceration in close proximity to coronary arteries in which careful placement of horizontal mattress sutures deep to the coronary artery is required to avoid compromise or occlusion of coronary blood flow.47 Concomitant intracardiac injuries always should be suspected. However, the diagnosis of such injuries is difficult to make clinically or on physical examination. In this case, the use of TEE by the anesthesia team is very helpful. Most of the time, a cardiac anesthesiologist is not present in the middle of the night when a trauma patient usually presents. Most of the time such injuries do not require immediate repair, and TTE to rule out myocardial, septal, or valvular injury can be done postoperatively. In the event of an intracardiac injury and associated physiologic deterioration, cardiopulmonary bypass would be needed. In the intensive care unit, the most important things to watch for, apart from the usual physiologic monitoring of hemodynamic status or blood loss via chest tube output, is the development of various arrhythmias. A patient commonly may undergo a successful and difficult cardiac surgery only to die of fatal postoperative arrhythmias. In a large populationbased study, Ismailov et al48 found that patients with blunt cardiac injury had a twofold-to-fourfold increase in the risk of cardiac arrhythmia after chest injury, with atrial fibrillation being the most common. Careful monitoring of fluid status and electrolytes takes precedence in the postoperative phase. Overall, cardiac injury is extremely challenging even to an experienced surgeon. Teamwork and direct communication at the various stages of care are key to the successful management of these patients with high mortality and morbidity.

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