Cardiac BB Gun Injury With Missile Embolus to the Lung

Case Report The Journal of TRAUMA威 Injury, Infection, and Critical Care Cardiac BB Gun Injury With Missile Embolus to the Lung Carl-Christian A. Jackson, MD, Mudiwa Munyikwa, MD, Emile A. Bacha, MD, Mindy B. Statter, MD, and Joanne P. Starr, MD J Trauma. 2007;63:E100 –E104. A s an air-powered firearm, BB guns are often considered to be toys. They have the potential to cause life-threatening injuries. Air gun injury to the heart presents several diagnostic and therapeutic challenges. When faced with an unstable patient sustaining cardiac injury from an air gun with subsequent pellet embolization, questions arise as to appropriate management. We present such a case, with a review of the literature addressing operative treatment of the wound, the use of cardiopulmonary bypass (CPB) in the repair, and whether embolectomy should be attempted. CLINICAL SUMMARY A 9-year-old, 45-kg boy presented to the trauma bay of the University of Chicago Children’s Hospital after sustaining a close range (1 m) BB gunshot to the left chest. En route, the patient was responsive, but not alert. On arrival to the trauma bay, he was pale and diaphoretic. His vital signs were heart rate 136 bpm, blood pressure 50/palpation, palpable femoral pulses, respiratory rate 33 breaths/min, and oxygen saturation 99% on face mask, with a Glasgow Coma Scale score of 14. During the primary survey, the patient’s level of consciousness deteriorated, necessitating a rapid sequence intubation. Breath sounds were decreased over the left chest and a left tube thoracostomy was performed. No air leak or effusion was noted. Fluid resuscitation was achieved via two largebore peripheral intravenous cannulae with improvement of the patient’s blood pressure to 108/palpation but without change in his tachycardia. The secondary survey revealed a single penetrating wound to the left chest, 2 cm medial to the nipple. An emergency department (ED) ultrasound examination of the heart revealed pericardial blood and clot (Fig. 1). An ultrasound-guided pericardiocentesis returned a small amount of blood, without significant sustained improvement Submitted for publication October 5, 2004. Accepted for publication June 22, 2007. Copyright © 2007 by Lippincott Williams & Wilkins From the Sections of Pediatric Surgery (C-C.A.J., M.B.S.), Cardiothoracic, Pediatric, and Congenital Cardiac Surgery (M.M., E.A.B., J.P.S.), University of Chicago Children’s Hospital, Chicago, Illinois. Address for reprints: Joanne P. Starr, MD, Children’s Hospital of New Jersey, Newark Beth Israel Medical Center, 201 Lyons Avenue, Newark, NJ 07112; email: [email protected]. DOI: 10.1097/TA.0b013e3181469ea7 E100 in vital signs. Lateral and anteroposterior portable chest radiographs demonstrated the missile to be located behind the heart, in the lower left lobe of the lung. (Fig. 2) The patient was taken emergently to the operating room (OR) for exploration. Chest X-ray (CXR) film findings of a missile behind the cardiac silhouette raised the concern for a through-andthrough cardiac injury. Therefore, a median sternotomy was performed revealing a tense, blood-filled pericardium. Upon incising the pericardium, there was a large amount of blood and clot in the pericardial space. After removal of the majority of blood and clot, there was an actively bleeding, 3-mm penetrating wound on the anterior surface of the right ventricle (RV) approximately 0.5 cm to 1.0 cm to the right of the mid-left anterior descending coronary artery. Direct pressure was placed over this wound. Attempts to manipulate the heart and inspect for a posterior injury caused significant hypotension. Therefore, we placed the patient on cardiopulmonary bypass via the right atrium and aorta to perform a thorough cardiac examination. After repairing the right ventricular injury with a pledgetted 4-0 Prolene mattress suture, further examination of the heart and pericardial space revealed no other injury. Next, the left pleural space was opened and examination revealed no identifiable lung injury and no palpable foreign body in the left lung parenchyma. An intraoperative transesophageal echocardiogram (TEE) further demonstrated no evidence of traumatic or congenital septal defects. At this point we concluded that the BB had penetrated the RV, embolized to the left pulmonary artery, and subsequently to its final position in the left lower lobe. Because there was no evidence of pulmonary compromise and the missile was not easily palpable, it was left in place. The patient separated easily from CPB on dopamine of 5 ␮g/kg⫺1/min⫺1, and in sinus rhythm. Total CPB time was 34 minutes. The chest was closed in a standard fashion with interrupted sternal wires and a single anterior mediastinal chest tube. The patient was transferred to the Pediatric Intensive Care Unit, intubated and in stable condition. The patient’s postoperative course in the Pediatric Intensive Care Unit was uncomplicated, allowing extubation on postoperative day (POD) 1 and advancement of diet. The chest tube was removed on POD 2 and the patient was transferred to the pediatric floor. Before discharge on POD 5, a postoperative CXR film demonstrated that the BBs position was unchanged. October 2007 Cardiac BB Gun Injury Fig. 1. Emergency room ultrasound of the heart. Pericardial effusion (closed arrow). At the 2-month and 16-month follow-ups, both transthoracic echocardiogram and CXR were performed, showing no abnormalities and a stable position of the BB (Fig. 3). DISCUSSION Despite improved prehospital and hospital care, overall survival after gunshot wounds to the heart is 16% to 23%.1,2 However, for the population of victims who arrive to the ED with intact vital signs (spontaneous ventilation, heart rate, and blood pressure) survival improves to 70% to 75%.1,3 Among patients with cardiac injuries who do require an emergent thoracotomy, there is a significantly improved survival rate for those patients stable enough to undergo an OR thoracotomy versus an ED thoracotomy (23% vs. 2.8%).2 As can be expected, better physiologic status at presentation to the ED confers a survival advantage. The problem of firearm-related injury is certainly not specific to adults. In children under the age of 16, there are approximately 4,500 firearm-related deaths per year and in an institutional review spanning 9 years, 1% of these deaths were caused by air gun injury.4 The common perception of air guns as toys is therefore misguided. When examining the kinetics of air guns, the potential for serious injury is readily apparent. Ballistic studies of air gun pellets found that skin penetration occurs at a velocity of 331 feet/s for a 0.177 caliber pellet and at 245 feet/s for a 0.22 caliber pellet.5 Pneumatic rifles are all capable of firing pellets at velocities in excess of 390 feet/s, and some can reach more than 900 feet/s.6 For comparison, the muzzle velocity of a conventional (powder) 0.22 caliber rifle is 800 to 1,000 feet/s, and a 0.38 caliber revolver exceeds 750 feet/s.6 Because of the low mass of the pellet, kinetic energy is lost quickly but at close range (5–10 feet) this loss is minimal. The literature contains numerous reports of air gun fatalities, which generally result from injury to either the head or chest from air guns being fired at close range.4,7–11 Volume 63 • Number 4 Fig. 2. Lateral and anteroposterior portable chest radiographs taken in the emergency room. BB pellet in left lower lobe (arrow). A problem with nonfatal air gun injuries, especially those to the chest, is the propensity for the missile to embolize because of its low mass and size. Depending on the site of entry into the vascular system, embolization of any missile can be to arterial, pulmonary, or even venous systems.12–15 The presence of a missile embolus in the pulmonary arterial system raises a question of management, namely whether to operatively extract them. Symbas and Harlaftis reported on 10 patients with bullet emboli, 5 of which were to the pulmonary artery.16 Four of the five patients with pulmonary emboli were successfully treated with embolectomy and remained well at follow-up. Stephenson et al. reported on two cases of bullet emboli to the pulmonary artery, and reviewed E101 The Journal of TRAUMA威 Injury, Infection, and Critical Care Fig. 3. Lateral and anteroposterior portable chest radiographs at 2-month follow-up. BB pellet position unchanged (arrow). 15 additional cases from the literature.17 Nine of the patients underwent thoracotomy and embolectomy. In four of these patients, the bullet dislodged intraoperatively and migrated to the opposite lung, requiring a second thoracotomy on the opposite chest to retrieve the bullet. Thus, attempts at embolectomy are not without risk and should not be taken lightly. In fact, current practice is to leave pulmonary or cardiac missiles in situ as long as certain criteria are met. A missile may be observed if it is located in the right heart or pulmonary vasculature, there is no evidence of arrhythmia, there is no valvular dysfunction, the missile is smooth, the missile is ⬍5 mm, the missile is firmly lodged, and the missile is uncontaminated by passage through organs of the gastrointestinal E102 tract.13 In our particular case, it remains to be seen if the pellet will cause any adverse effects, such as migration to the systemic circulation, empyema, or abscess formation. The patient was asymptomatic at the 16-month follow-up. Operative management of air gun cardiac injuries is reserved for patients who show evidence of clinical instability, such as arrhythmia or tamponade.18,19 Missile embolectomy has a reported mortality as high as 9.5% and therefore should not be undertaken lightly.20 There are, in general, three options for operative exploration: a left thoracotomy in the ED (EDT), a left thoracotomy in the OR, or a median sternotomy in the OR. As mentioned previously, patients who require an EDT represent the most unstable patients and have the poorest prognosis. In their institutional review, Ladd et al. found that in patients sustaining penetrating cardiac injury and requiring an EDT, survival increased to 16.2% if the procedure was performed on patients with measurable blood pressures and pulses.3 There were no survivors in patients with no signs of life or those with only pulseless electrical activity and no measurable blood pressure or pulse. For those patients stable enough to be transported to the OR for exploration, the heart can be approached by either a left thoracotomy or a median sternotomy. In a review of their experience with penetrating cardiac injuries, Mitchell et al. describe their experience using both approaches.21 Left thoracotomy is the traditional choice for exploration because it provides excellent exposure of the lung, thoracic aorta, and left mediastinum. Exposure of the heart can be limited, and transsternal extension with selective right thoracotomy was occasionally required (25% of patients). A median sternotomy provides excellent access to the heart and anterior mediastinum, but more limited access to the thoracic cavities and posterior mediastinum. This approach also more readily accommodates CPB should it be required. Further, patients show better pulmonary function with less need for pain medication after a median sternotomy.22–24 Mitchell et al. concluded that in the hemodynamically stable patient, their incision of choice is median sternotomy, saving left thoracotomy for those patients who require immediate interventions such as aortic cross-clamping, pericardial decompression, or open cardiac massage.21 For patients requiring a sternotomy for their cardiac injury, subsequent repair can be performed either on CPB or off-pump. Most free wall and coronary injuries can be handled off bypass. CPB is usually reserved for intracardiac injuries and extensive free wall and coronary injuries. Offpump repair using cardiac stabilization devices have been described for penetrating trauma.25 Off-pump repair is preferred because one avoids systemic heparinization, which can be deleterious especially in the setting of associated injuries (i.e., head trauma). In our patient, the RV free wall injury very likely could have been repaired off bypass. However, we were not able to perform a thorough exploration without bypass because of clinically significant hypotension with cardiac manipulation. October 2007 Cardiac BB Gun Injury TEE has been used in blunt and penetrating cardiac trauma. Penetrating cardiac trauma not only can cause injury to the free wall of the heart and great vessels, but also to the interatrial and interventricular septa, cardiac valves, conduction system, and coronary arteries. The incidence of intracardiac injuries after penetrating injury has been reported to be anywhere between 4% and 56%. Many of the injuries are detected days to weeks posttrauma.26 Hemodynamically significant septal and leaflet injuries should be dealt with in a timely fashion as delay can cause significant morbidity and mortality. TEE can provide comprehensive intracardiac evaluation of the heart intraoperatively and prevent delay in repair of significant injuries. Mollod et al. reviewed 16 consecutive trauma patients specifically referred for TEE by trauma and cardiothoracic services. Ten of the 16 patients had penetrating trauma. Seven of the 10 penetrating trauma patients had significant intracardiac or aortic injuries requiring surgical repair. The authors state that TEE influenced the treatment of each patient including the timing of the surgical intervention, type of repair, precise location of an intracardiac foreign body, time to extubate, and optimal medical therapy.27 In our patient, TEE demonstrated no evidence of intracardiac injury by the missile. Repair of an intracardiac injury, had it been identified, would have depended on the extent of the injury and the hemodynamic status of the patient. There are an estimated 17,438 children aged 19 years and younger who are treated annually for nonfatal air gun injuries.28 The persons at highest risk for sustaining an air gun injury are boys, aged 10 to 14 years, with the vast majority of injuries being unintentional.8,28 Of further concern is the fact that about 75% of the shootings happen in the home environment, and in up to 21% of the cases the shooter is an immediate family member.4,8 Trends in air gun injuries are encouraging, however. An increased injury rate from 1988 to 1992 was followed by a steady decline through 1999.28 A search of state laws pertaining to air guns, and firearms in general, reveals that from 1994 to 1996 the number of states restricting the use and sale of air guns to minors has increased from 14 to 28.29,30 By the year 2000, that number has further increased to 48.29 Currently, 11 states classify air guns as firearms or dangerous weapons, 19 states hold parents or guardians legally responsible for injuries or deaths resulting from minors using firearms, and 10 states legally require parents or guardians to store firearms safely away from minors.28,31 Safe storage practices alone have contributed to a 23% decrease in unintentional firearm-related deaths in children under 15 years of age.32 Although progress has been made, public awareness, adult supervision, safety training, and appropriate legislation continue to be critical in decreasing the risks of these potentially lethal weapons. Despite seeming to be harmless toys, air guns have the potential to inflict serious cardiac injury. Proper management Volume 63 • Number 4 requires a high degree of respect for the potential damage caused by an air gun. Patients should be managed in the trauma bay using Advanced Trauma Life Support protocols, just as if they sustained an injury from a conventional firearm. Observation may be appropriate for asymptomatic patients, but operative treatment should follow the established protocols for treating traumatic cardiac injuries, with CPB employed as needed for safe exploration and repair. Further, embolectomy is not required for pulmonary missile emboli as long as certain established criteria are followed. Although this article is a single case report, it is an important addition to the literature. Few reports of distal pulmonary embolization have been made; our patient had long-term follow-up without adverse consequences, which further supports that embolectomy is not necessary in all cases. REFERENCES 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. Asensio JA, Berne JD, Demetriades D, et al. One hundred five penetrating cardiac injuries: a 2-year prospective evaluation. J Trauma. 1998;44:1073–1082. Tyburski JG, Astra L, Wilson RF, et al. Factors affecting prognosis with penetrating wounds of the heart. J Trauma. 2000;48:587–590; discussion 590 –581. Ladd AP, Gomez GA, Jacobson LE, et al. Emergency room thoracotomy: updated guidelines for a level I trauma center. Am Surg. 2002;68:421– 424. Beaver BL, Moore VL, Peclet M, et al. Characteristics of pediatric firearm fatalities. J Pediatr Surg. 1990;25:97–99; discussion 99 –100. DiMaio VJ, Copeland AR, Besant-Matthews PE, et al. Minimal velocities necessary for perforation of skin by air gun pellets and bullets. J Forensic Sci. 1982;27:894 – 898. Harris W, Luterman A, Curreri PW. BB and pellet guns—toys or deadly weapons? J Trauma. 1983;23:566 –569. Ng’walali PM, Ohtsu Y, Muraoka N, et al. Unusual homicide by air gun with pellet embolization. Forensic Sci Int. 2001;124:17–21. Bratton SL, Dowd MD, Brogan TV, et al. Serious and fatal air gun injuries: more than meets the eye. Pediatrics. 1997;100:609 – 612. Fernandez LG, Radhakrishnan J, Gordon RT, et al. Thoracic BB injuries in pediatric patients. J Trauma. 1995;38:384 –389. Lawrence HS. Fatal nonpowder firearm wounds: case report and review of the literature. Pediatrics. 1990;85:177–181. Milroy CM, Clark JC, Carter N, et al. Air weapon fatalities. J Clin Pathol. 1998;51:525–529. Michelassi F, Pietrabissa A, Ferrari M, et al. Bullet emboli to the systemic and venous circulation. Surgery. 1990;107:239 –245. Nagy KK, Massad M, Fildes J, et al. Missile embolization revisited: a rationale for selective management. Am Surg. 1994;60:975–979. Rich NM, Collins GJ Jr, Andersen CA, et al. Missile emboli. J Trauma. 1978;18:236 –239. Taggart DP, Mackenzie I. Air gun pellet embolism. Scott Med J. 1988;33:340. Symbas PN, Harlaftis N. Bullet emboli in the pulmonary and systemic arteries. Ann Surg. 1977;185:318 –320. Stephenson LW, Workman RB, Aldrete JS, et al. Bullet emboli to the pulmonary artery: a report of 2 patients and review of the literature. Ann Thorac Surg. 1976;21:333–336. Alejandro KV, Acosta JA, Rodriguez PA. Air gun pellet cardiac injuries: case report and review of the literature. J Trauma. 2003; 54:1242–1244. DeCou JM, Abrams RS, Miller RS, et al. Life-threatening air rifle injuries to the heart in three boys. J Pediatr Surg. 2000;35:785–787. E103 The Journal of TRAUMA威 Injury, Infection, and Critical Care 20. 21. 22. 23. 24. 25. Massad M, Slim MS. Intravascular missile embolization in childhood: report of a case, literature review, and recommendations for management. J Pediatr Surg. 1990;25:1292–1294. Mitchell ME, Muakkassa FF, Poole GV, et al. Surgical approach of choice for penetrating cardiac wounds. J Trauma. 1993;34: 17–20. Asaph JW, Keppel JF. Midline sternotomy for the treatment of primary pulmonary neoplasms. Am J Surg. 1984;147:589 –592. Cooper JD, Nelems JM, Pearson FG. Extended indications for median sternotomy in patients requiring pulmonary resection. Ann Thorac Surg. 1978;26:413– 420. Urschel HC Jr, Razzuk MA. Median sternotomy as a standard approach for pulmonary resection. Ann Thorac Surg. 1986;41:130 –134. Fedalen PA, Frank AM, Piacentino V III, et al. Off-pump extraction of an embedded high posterior left ventricular bullet utilizing a new cardiac stabilization device. J Trauma. 2001;51:1011–1013. E104 26. 27. 28. 29. 30. 31. 32. Topaloglu S, Aras D, Cagli K, et al. Penetrating trauma to the mitral valve and ventricular septum. Texas Heart Inst J. 2006;33:392–395. Mollod M, Felner JM. Transesophageal echocardiography in the evaluation of cardiothoracic trauma. Am Heart J. 1996;132:841– 849. Nguyen MH, Annest JL, Mercy JA, et al. Trends in BB/pellet gun injuries in children and teenagers in the United States, 1985–99. Inj Prev. 2002;8:185–191. McNeill AM, Annest JL. The ongoing hazard of BB and pellet gunrelated injuries in the United States. Ann Emerg Med. 1995;26:187–194. Naude GP, Bongard FS. From deadly weapon to toy and back again: the danger of air rifles. J Trauma. 1996;41:1039 –1043. Bureau of Alcohol TaF. State Laws and Published Ordinances—Firearms. 22nd ed. Springfield, VA: U.S. Department of Treasury; 2000. Cummings P, Grossman DC, Rivara FP, et al. State gun safe storage laws and child mortality due to firearms. JAMA. 1997;278:1084 –1086. October 2007