Sunday, 13 March 2016

TOP 80 Trauma and Burns Multiple choice Questions and Answers

21. Which of the following statement(s) is/are true concerning the diagnosis of a peripheral vascular injury?
a. The presence of a Doppler signal over an artery in an extremity essentially rules out an arterial injury
b. Doppler examination is a valuable tool in the diagnosis of venous injuries
c. A gunshot wound in the proximity of a major vessel is an absolute indication for arteriography
d. Both the sensitivity and specificity of arteriography of the injured extremity approaches 100%
Answer: d

Segmental arterial pressure determination by Doppler technique is a valuable adjunct to the physical examination of extremity vascular trauma. The presence of audible Doppler signals over an artery in the extremity does not rule out an arterial injury or indicate adequate perfusion. In the healthy and normovolemic person, the normal ankle-brachial index is 1:1. A ratio less than 0.9 or a 20-mm Hg difference between extremities should arouse the suspicion of significant arterial trauma. Doppler examination has not been widely used to screen for significant venous injuries and is of unproven value. The selective use of arteriography is fundamental to the evaluation of patients with suspected vascular trauma. The indications for arteriography generally have included a history of moderate hemorrhage at the penetrating injury site, injury in proximity to major arterial structures, diminished pulses, and peripheral nerve injury in the distribution of a nerve that is in proximity to a major vessel. Proximity as the sole indication for arteriography in the absence of diminished ankle-brachial ratio or other signs of major trauma, has proven to be an unreliable indicator of the need for arteriography. In the absence of classical signs of major vascular injury, patients with penetrating wounds in proximity to major vessels may be observed closely without arteriography. The use of arteriography can significantly reduce the rate of unnecessary exploration for suspected vascular trauma. If routine surgical exploration is performed whenever vascular injury is suspected, a negative exploration rate of about 60% or more can be expected. Selective use of arteriography reduces the negative exploration rate to about 35%. Arteriography is an extremely reliable method of excluding vascular trauma. In this context, the sensitivity is 97% to 100% and the specificity is 90% to 98%, with an overall accuracy between 92% and 98%.

22. A 22-year-old male is hospitalized with multiple extremity fractures including a comminuted fracture of the femur and multiple rib fractures. Which of the following statement(s) is/are true concerning his hospital course? 
a. Low-dose heparin should not be employed during his hospital stay
b. Acute respiratory failure associated with petechiae of the head, torso, and sclerae would suggest a pulmonary embolism
c. Early fracture fixation would decrease the incidence of fat emboli
d. The placement of a Greenfield filter should be avoided due to the risk of lower extremity edema
Answer: c

Perhaps the most catastrophic post-injury complication is pulmonary embolism. All patients with orthopedic injury, particularly those with fractures of the lower extremities or pelvis, are at high risk for deep venous thrombosis and subsequent pulmonary embolism. Prophylaxis with sequential compression devices or low dose heparin has reduced the incidence of deep venous thrombosis in this group. Although concern for the use of heparin is appropriate, prospective studies demonstrate that low-dose heparin therapy can begin safely within 24 hours in 37% of patients and within 48 hours in 75%. Trauma patients who are paralyzed or immobilized by head injury, spine injury, or multiple orthopedic injuries should be considered for placement of a Greenfield filter.
Fat embolism syndrome is a classic triad of acute respiratory failure; altered mental status, and petechiae of the head, torso and sclerae; and is frequently associated with long-bone and pelvic fractures. Less fulminant presentations, without petechiae and with lesser degrees of pulmonary dysfunction, are more common. At present, the only therapy for fat emboli syndrome is supportive care. Therefore, prevention is critical and numerous studies indicate that early fracture fixation decreases the incidence of this and other pulmonary complications. However, a subset of patients with femoral fractures and coexisting lung contusion has been recently found to have a higher incidence of ARDS if the fracture is repaired early than if repaired late.

23. A middle-aged construction worker had a significant fall on the job and presents with obvious high cervical spine injury. Which of the following statement(s) is/are true concerning his diagnosis and management? 
a. A paradoxical breathing pattern in which the abdomen protrudes on inhalation may be observed
b. If the patient appears well compensated on initial evaluation, intubation is unlikely to be necessary
c. The presence of hypotension strongly suggests significant blood loss from associated injury
d. The patient’s extremities are likely to appear warm and well perfused despite the presence of hypotension
e. The use of methylprednisolone beginning 24 hours after the injury will be indicated
Answer: a, d

Fractures to the axial spine, especially in the high cervical spine, can cause varying degrees of respiratory compromise. Patients with ventilatory failure from acute cord injury typically present with a paradoxical breathing pattern in which the abdomen protrudes on inhalation, creating a see-saw appearance. This is caused by paralysis of abdominal musculature and is seen with injuries as low as T-10 to T-11. Early endotracheal intubation and mechanical ventilation must be considered, even in patients who appear compensated on initial evaluation. There is a strong tendency for such patients to tire and develop respiratory failure a few hours after the injury.
In addition to ventilatory compromise, high axial spinal lesions can cause significant hypotension, confusing the initial evaluation of the patient. Most CNS control of arterial tone is mediated through the sympathetic nervous system. In high thoracic and cervical spinal cord injuries, these controlling pathways may be interrupted, with subsequent loss of vasomotor tone. This results in hypotension even without significant blood loss. Unlike hypovolemic shock, the patient’s extremities are warm and well perfused.
A prospective, randomized trial has suggested that high doses of methylprednisolone given within 8 hours of injury have improved neurologic recovery. Starting treatment with steroids more than 8 hours after injury results in worse recovery than the placebo and is not recommended.

24. Which of the following statement(s) is/are true concerning Emergency Room thoracotomy?
 a. Overall survival rates approach 25%
b. Blunt trauma patients without signs of life upon arrival in the Emergency Room are candidates for Emergency Room thoracotomy
c. All patients with penetrating trauma to the chest and the absence of vital signs are candidates for ER thoracotomy
d. None of the above
Answer: d

A recent meta-analysis of 24 reports concerning the outcome of Emergency Room thoracotomy found that the overall survival rate was 11%. There were no survivors among patients with no signs of life (supraventricular electrical activity, pupillary reaction, and agonal respirations) at the scene. In addition, there were no neurologically intact survivors among blunt trauma patients without signs of life upon arrival in the Emergency Department. Considering these findings, an appropriate algorithm would indicate that Emergency Room thoracotomy for penetrating trauma is indicated only if patients had signs of life at the scene and had lost signs of life less than five minutes prior to arrival in the Emergency Room. Blunt trauma patients would be allowed Emergency Room thoracotomy only if the patient had signs of life upon arrival at the Emergency Room. If patients meet these criteria and lose cardiac function, airway placement and fluid resuscitation is initiated simultaneously with or immediately followed by left anterior thoracotomy, pericardiotomy, and internal cardiac massage.

25. An untreated or an unrecognized compartment syndrome produces nerve and muscle damage and prevents good functional recovery despite the patency of vascular repair. Which of the following factors suggests the need for a fasciotomy? 
a. A period of 6 hours or more between injury and restoration of perfusion
b. Combined arterial and venous injuries
c. Postoperative signs of muscle pain or pain on passive stretch
d. Elevated compartment pressures
answer: a, b, c, d

Factors that suggest the need for fasciotomy are as follows:

1. Prolonged period (6 hours or more) between injury and restoration of perfusion
2. Associated crush injury
3. Preoperative calf swelling
4. Combined arterial and venous injuries
5. Extensive venous ligation
6. Postoperative signs or disproportionate muscle pain, pain on passive stretch, or tender and firm muscles
7. Elevated compartment pressures

26. Which of the following statement(s) is/are true concerning the consequences of vascular injuries?

a. Outcome is time-dependent
b. Further injury can take place after restoration of blood flow
c. Acute acidosis, hyperkalemia and myoglobin-induced renal failure can be consequences of severe extremity ischemia
d. Ischemia to peripheral nerves and muscles can be tolerated to up to four hours without permanent injury
Answer: a, b, c, d

Local consequences of vascular injuries are generally related to acute arterial occlusion from thrombosis after injury. The results of ischemia distal to the injury sites may lead to limb or organ loss. The degree of tissue loss is related to the adequacy of collateral flow, the sensitivity of distal tissue to ischemia, and the delay involved in repairing the injury and restoring blood flow. With regard to these latter issues, the variability is great. The brain is more sensitive to ischemia because of high basal energy requirements in the absence of glycogen stores. Brain ischemia for longer than 4 minutes results in irreversible injury. The nerves and muscles are much more resilient, tolerating periods of ischemia up to 4 hours without permanent injury. An important principle of vascular repairs, however, is that the outcome is time-dependent, necessitating an aggressive approach and a high priority.
The mechanism of injury from acute arterial ischemia includes both the initial anoxic phase when blood flow is ceased and reperfusion phase after restoration of blood flow. Termed the reperfusion injury, this phase includes the production of toxic metabolites and an inflammatory response which causes significant endothelial damage. The events associated with restoration of arterial blood flow after complete ischemia extend the magnitude and severity of the original insult in skeletal muscle and peripheral nerves. If the severity of ischemia is significant enough to cause skeletal muscle necrosis, rhabdomyalysis with the release of potassium and myoglobin into the systemic circulation follows. Acute acidosis, hyperkalemia, and myoglobin-induced renal failure can occur.

27. Which of the following statement(s) is/are true concerning the surgical management of vascular injuries?

a. A direct approach through the site of injury is often effective as the initial step
b. Systemic heparinization must be avoided in patients with multiple injuries
c. Reversed saphenous vein from the same extremity is the first choice as an interposition graft for extensive arterial injuries
d. Venous repair should not be attempted in a hemodynamically unstable patient
Answer: b, d

The goal of operative management of vascular injuries is the rapid control of hemorrhage and the restoration of perfusion, with salvage of extremity or organ in jeopardy. In isolated-extremity vascular injury with arterial occlusion, systemic heparin should be administered to avoid propagation of thrombus in vessels distal to the occlusion. In multiple-injury patients, especially those with central nervous system trauma, heparin is inappropriate. The initial steps in the surgical management of vascular injuries is to obtain proximal and distal control of the injured vessel. This is most easily accomplished through uninjured areas adjacent to the injury using incisions normally employed for elective exposure of these vessels. Direct approach to the site of injury is fraught with the hazards of severe hemorrhage and iatrogenic trauma to the vessel itself or adjacent nerves. The management of the arterial injury is determined by the extent of injury. In a repair of more extensive arterial injuries, reversed saphenous vein from an uninjured lower extremity is the first choice for an interposition graft. The repair of concomitant venous injuries is a controversial injury. Proximal extremity veins and the great veins are repaired whenever technically possible to avoid the sequela of venous occlusion. Venous repair should not be attempted, in a hemodynamically unstable patient; rather, ligation should be performed to expedite the operation.

28. Penetrating injuries to the pancreas and duodenum are uncommon occurring in 4% and 6% of patients, respectively. Which of the following statement(s) is/are true concerning the management of pancreaticoduodenal injuries?

a. The Kocher maneuver is essential for providing exposure for the duodenum
b. A large injury of the duodenum which cannot be closed primarily will always require a pancreaticoduodenectomy
c. Pyloric exclusion involves suture or staple closure of the pylorus, gastrojejunostomy, tube decompression of the duodenum, and placement of a T-tube in the common bile duct
d. Class III injuries of the head of the pancreas should be treated with simple external drainage rather than resection
Answer: a, d

Because of the retroperitoneal location of the duodenum and pancreas and the close proximity to a number of viscera and major structures, isolated penetrating injuries to the duodenum and pancreas are rare. Diagnosis of pancreaticoduodenal injuries depends on adequate exposure. A Kocher maneuver whereby the duodenum and head of the pancreas are mobilized from the retroperitoneal position by excising the lateral peritoneal reflection of the duodenum is essential for this exposure. Most penetrating injuries of the duodenum are simple lacerations that can be repaired primarily. Large injuries to the duodenum are more difficult to repair. Injuries of greater than 50% can lead to luminal compromise if repaired primarily. Treatment with a jejunal patch or duodenojejunostomy with a defunctionalized Roux-en-Y limb of jejunum can avoid the need for pancreaticoduodenectomy and its associated substantial mortality. Since many duodenal repairs are tenuous especially in combination with pancreatic injury and the concern about the digestive action of activated pancreatic enzymes on the repair, the technique of pyloric exclusion has been devised and is advocated by some. Pyloric exclusion involves suture or staple closure of the pylorus and restoration of gastrointestinal continuity by performing a gastrojejunostomy. Tube decompression of the duodenum should be performed in severe duodenal injuries but the biliary tract does not require decompression unless there has been an associated biliary tract injury. The management of pancreatic injuries depends on the location with respect to the head, body, and tail of the gland. Class III injuries of the head of the pancreas involve a relatively severe injury. In almost all situations, these injuries should simply be drained without attempts at resection or emergency internal drainage. If a patient develops a pancreatic fistula, the fistula can be controlled by the drain. If the fistula does not resolve with time, the pancreas can be drained internally at a later date.

29. A CT scan is performed on this patient. Which of the following statement(s) is/are true concerning the findings on CT scan and the patient’s management?

a. The CT finding that correlates most significantly with intracranial hypertension is compression or obliteration of the basilar cisterns
b. Intracranial pressure monitoring is indicated immediately in any patient with cisternal compression.
c. A brain contusion appears as a very homogeneous high density area in the cerebral cortex
d. Intracerebral hematomas are routinely treated with craniotomy
Answer: a, b

The CT finding which correlates most significantly with intracranial hypertension is compression or obliteration of the basilar cisterns. Not only does this finding portend a stormy intracranial pressure course, but the primary predictor of outcome in patients with this CT picture is the peak level intracranial hypertension occurring during the first 72 hours. Intracranial pressure monitoring should be immediately initiated in any patient with cisternal compression and the intracranial hypertension should be vigorously treated. Intracerebral hemorrhage and cerebral contusion are common after trauma and are readily visualized on CT scan. Brain contusion appears as a focal, heterogeneous density with hemorrhage interspersed with injured tissue. Intracerebral hematomas are generally more homogeneous in their high density appearance. These lesions tend to “blossom” over time due to continued hemorrhage and the development of edema. Therefore, it is important to closely observe and monitor the ICP of such patients because a significant and hazardous mass effect may evolve, requiring surgical extirpation. Cerebral contusions and intracerebral hematomas are treated operatively only when a mass effect results in intracranial hypertension or signs of herniation.

30. Which of the following statement(s) is/are true concerning the management of chest trauma?

a. The majority of injuries to the chest require surgical intervention
b. The posterior lateral thoracotomy is the optimal approach for emergency thoracotomy
c. Either computed tomography or angiography are suitable methods for detecting aortic disruption in a patient with an abnormal chest x-ray
d. Persistent bleeding associated with a penetrating injury to the chest is often due to injury to an artery of the systemic circulation
Answer: d

The chest radiograph is by far the most important diagnostic study in patients with chest trauma and should be obtained early in all patients. Angiography is the best study to rule out major injury to the great vessels in the chest, and angiography remains mandatory in the majority of patients at risk for aortic disruption who have an abnormal chest radiograph. At the present time, CT scan of the chest appears to have a higher rate of missed injury than angiography for assessment of the aorta and should probably be avoided in patients with abnormal chest films.
The majority of injuries to the chest can be successfully managed without surgical intervention. The routine use of a tube thoracostomy for treatment of hemothorax and pneumothorax is the cornerstone of therapy. Thoracotomy is most often needed for the control of massive bleeding, or bleeding which persists despite tube thoracostomy. About 80% to 85% of hemorrhages within the chest can be treated by tube thoracotomy alone. Even larger and deep lacerations of the lung parenchyma, which bleed with relatively low pressure from the pulmonary circulation, will be controlled by the reinflated lung parenchyma as well as edema in the tissue from the injury. Persistent bleeding is most commonly due to injuries to major proximal branches of the pulmonary circulation or injuries to systemic arteries including intercostal arteries and internal mammary arteries. The choice of position and surgical approach for thoracotomy for thoracic injury is dictated by the nature of the patient’s injuries, the certainty of diagnosis, and the potential for associated injuries involving other body sites. Although the standard postero-lateral thoracotomy provides optimal exposure to the contents of a particular hemithorax, the lateral position of the patient makes access to the other side of the chest or abdomen difficult if not impossible. Therefore, though postero-lateral thoracotomy provides the best access, it can be used only in patients who have injuries isolated to a given hemithorax. In most patients undergoing emergency thoracotomy for chest trauma, an antero-lateral approach must be used in patients supine to allow access to the abdomen and contralateral chest cavity. Although exposure through this incision is considerably more difficult, it is adequate with proper technique. Median sternotomy incision provides excellent exposure to the heart and the great vessels in the anterior mediastinum, but it provides very difficult exposure for repair of injuries to the lungs, descending aorta, chest wall, diaphragm, or esophagus. Therefore, like the postero-lateral thoracotomy, it can be used only when the patient’s injuries can be determined with relative certainty.

31. The anterior neck is divided into three zones defined by horizontal planes. Which of the following statement(s) is/are true concerning penetrating injuries to the anterior neck?

a. Penetrating injuries to Zone I carry the highest mortality
b. Injuries to Zone II are the most common and the mortality rate is second only to those of Zone I
c. Exposure of Zone III for detection of injuries to the distal carotid artery and pharynx can be quite difficult
d. All hemodynamically stable patients with penetrating injuries to Zone I should have angiography
e. Most vascular lesions in Zone III are best treated by surgical exploration
Answer: a, c, d

The anterior neck is divided into three zones defined by horizontal planes. Zone I represents the base of the neck and it invariably extends from the sternal notch to the top of the clavicles or the cricoid cartilage. Injuries here carry the highest mortality because of the risk of major vascular and intrathoracic injury. Zone II is the mid-body and largest portion of the neck. It extends from the top of Zone I to the angle of the mandible. Zone II injuries are most common but carry a lower mortality rate than either Zone I or Zone III injuries, since the injury is generally apparent and exposure of the vital structures is readily accomplished. Zone III is that part of the neck above the angle of the mandible. The risk of injury to the distal carotid artery, salivary glands and pharynx is greatest in this zone. Exposure in this region can be particularly difficult.
Most surgical groups advocate exploration in the majority of penetrating neck wounds that penetrate the platysma in Zone II and in all patients with clinical signs of tracheal, esophageal, or major vascular injury. Preoperative angiography is generally not required for Zone II injuries because of the relative ease of exposure and control of critical vascular structures. Zone I and III penetrating injuries are selectively managed based on clinical presentation and the result of diagnostic studies. Hemodynamically unstable patients are immediately explored with operative incision based on the most likely source of vascular injury. Zone I injuries are essentially managed similar to mediastinal traversing wounds. Angiography is performed in all hemodynamically stable patients with penetrating wounds to Zone I to identify potential injuries to the thoracic outlet vessels or to plan better operative approach. Angiography is also performed for Zone III injuries, because of the possible inaccessibility of the internal carotid artery lesions or to demonstrate a need for systemic anticoagulation. Furthermore, most of the vascular lesions identified at the base of the skull are best managed by interventional angiography techniques.

32. Which of the following statement(s) is/are true concerning the definitive management of neck injuries?
a. Patients with evidence of an acute stroke following penetrating injury involving the carotid artery should be managed with arterial ligation
b. Unilateral vertebral artery occlusion usually results in a clear neurologic deficit and therefore revascularization is indicated
c. The combination of esophography and endoscopy improves the accuracy of detecting esophageal injury with penetrating trauma
d. External drainage is an important aspect of the surgical management of an esophageal injury
e. Arterial dissection secondary to blunt trauma is best managed by operative exploration and resection of the dissection
Answer: c, d

Blood vessels are the most commonly injured structures in the neck. Major arterial injuries occur in 18% of penetrating neck wounds and major venous injuries in 26%. Blunt vascular injures account for a very small percentage of carotid injuries, however their management is somewhat controversial with treatment highly variable dependent upon the vascular lesion as well as concomitant injuries. When anatomically feasible, pseudoaneurysms are probably best managed by resection. The best treatment for arterial dissection, however, although not completely resolved, would appear to be systemic anticoagulation if possible to prevent propagation, embolization or thrombosis. Resection may not be required in the majority of patients. Penetrating carotid injury most commonly presents with exsanguinating hemorrhage. The indication for repair versus ligation of a carotid injury depends, in part, on the neurologic presentation. Patients without a neurologic deficit and a carotid injury should have restoration of vascular continuity with good neurologic outcome anticipated. Also, patients with all grades of neurological deficits short of coma should have primary vascular repair. Although experience with revascularization of patients suffering acute stroke from arteriosclerotic occlusive disease suggests that hemorrhagic infarction and death may result from revascularization, several reviews of acute revascularization in the trauma patient note that combined morbidity and mortality are significantly less in those patients repaired primarily compared to those managed with arterial ligation. Traumatic injury to the vertebral arteries are now more commonly identified due to the more liberal application of neck angiography. Unilateral vertebral artery occlusion seldom results in a neurologic deficit. Treatment of blunt vertebral artery injury with thrombosis generally is nonoperative: systemic anticoagulation is recommended to avoid further propagation of existing thrombus.
The diagnosis of esophageal injury can be difficult. The sensitivity of esophography in detecting esophageal injuries varies from 50% to 90%; the sensitivity of endoscopy ranges from 29% to 100%. These modalities should be considered complimentary, and when combined have an accuracy of nearly 100%. Since virtually all reported deaths from cervical esophageal injuries are the result of delayed or misdiagnosis, a particularly high index of suspicion is warranted. When injured, the esophagus should be meticulously debrided and repaired primarily in one or two layers. It is important to drain all such wounds, because infection or salivary fistula is not an infrequent complication.

33. A 25-year-old male is involved in a motor vehicle accident with a significant head injury. Which of the following statement(s) is/are true concerning his injury and management?

a. A single episode of systolic blood pressure < 90 mm Hg occurring during the early period after injury significantly increases the chances of mortality and morbidity
b. Systemic hypertension should be avoided to reduce the risk of intracranial hemorrhage
c. The patient should be vigorously hyperventilated to reduce PaCO2
d. The patient should be heavily sedated and pharmacologically paralyzed after the initial neurologic examination
Answer: a

Brain injury is the most common cause of death in trauma victims, accounting for about half of deaths at the accident site. The injuries are generally the result of blunt trauma, and motor vehicle accidents are the most frequent cause. Head injuries involve not only the primary injury but secondary injuries which can result from the events occurring after the primary insult, due to either the direct consequences of a process initiated by the primary injury or to deleterious outside influences. The occurrence and magnitude of secondary insults is often the determining factor in outcome from brain injury. Since secondary insults, in contrast to primary injuries, are amenable to medical therapy, they are the focus toward which the medical treatment of brain injury is directed. The primary external secondary injury processes occurring following brain injury are hypotension and hypoxia. Hypotension is the number one treatable determinant of severe head injury. A single episode of systolic blood pressure less than 90 mm Hg occurring during the period from injury through resuscitation doubles the mortality and significantly increases the morbidity of any given brain injury. Intracranial hypertension may be considered as being deleterious via two somewhat separate mechanisms—herniation and ischemia. Herniation occurs when a pressure gradient exists across an incomplete barrier such as the tentorium or the falx cerebri. It is deleterious because of the tissue damage that results when herniation occurs. The second aspect of the intracranial hypertension that is deleterious is elevated resistance to cerebral blood flow, resulting in or exacerbating ischemia. Treatment of systemic hypertension is rarely indicated in the head injured patient. There is no evidence that hypertension promotes continued intracranial hemorrhage, and hypertension related to brain injury generally resolves when the intracranial hypertension is controlled. The treatment of intracranial hypertension involves elevating the head of the bed (reversed Trendelenburg position) but should only be performed after complete resuscitation has been accomplished. The confusion and agitation often attendant to head injury renders sedation desirable, therefore, patients with suspected head injury should generally be sedated. Pharmacologic relaxation, however, has the notable effect of limiting the neurologic examination to the pupils and, upon arrival to the hospital, the computed tomography scan. Therefore, its use in the absence of evidence of herniation should be limited to situations which sedation alone is not sufficient to optimize safe and efficient patient transport and resuscitation. When used, short acting agents are strongly preferred. Prophylactic administration of mannitol is not recommended due to volume depleting diuretic effect. In addition, although it is desirable to approximate the lower end of the normal range of PaCO2 during transport of a patient with suspected brain injury, the risk of exacerbating early ischemia by vigorous hyperventilation outweighs the questionable benefit in the patient without evidence of herniation. Therefore, ventilatory parameters consistent with optimal oxygenation and “normal” ventilation are recommended.

34. Which of the following statement(s) is/are true concerning the biomechanics of penetrating injuries?

a. Stab wounds are associated with significant cavitation
b. A hollow point bullet is associated with an enlarged area of injury
c. A high velocity gunshot wound creates a vacuum pulling clothing, bacteria, and other debris into the wound
d. The frontal area of impact of a bullet is determined by the caliber of the bullet
Answer: b, c

Penetrating trauma involves the transfer of energy to a relative small tissue area. The kinetic energy of a bullet disrupts and fragments cells and tissues, moving them away from the path of the bullet. The actual size of the frontal area of impact is determined by three factors—profile, tumble (spin and yaw), and fragmentation. A knife or jacketed bullet does not deform significantly during impact, whereas a hollow-point bullet flattens, spreads, and fragments on impact and therefore enlarges the area of injury. Low energy missiles including knives and other objects produce damage only by sharp cutting edges. Cavitation is minimal, and injury can be predicted simply by tracing the pathway of the weapon within the body. Low, medium and high velocity gunshot wounds, however, produce damage not only to tissue directly in the path of the missile but also produce cavitation injury to tissues in close proximity to the impact. The size of the cavitation injury is directly proportional to the bullet’s velocity. The essential difference between high velocity weapons and low and medium velocity weapons is that the higher velocity weapons have a much larger cavity or pressure cone than low-and medium-velocity missiles. The temporary cavity extends well beyond the actual bullet tract, producing a wider injury. The vacuum created by the cavitation pulls clothing, bacteria, and other debris from the surrounding areas into the wound, creating the additional risk of contamination.

35. In which of the following clinical situations is peritoneal lavage indicated?

a. A patient with suspected intraabdominal injury who will undergo prolonged general anesthesia for another injury outside the abdomen
b. A patient with a high velocity abdominal gunshot wound
c. A patient with an abdominal knife wound
d. A hemodynamically unstable patient with a high suspicion of intraabdominal hemorrhage
e. A patient with major noncontiguous injuries (i.e., chest and lower extremity)
Answer: a, c, e

Peritoneal lavage is a standard technique to detect significant intraabdominal hemorrhage after blunt trauma. Its applicability after low-velocity gunshot or stab wounds is less clear, but it has no place in the evaluation of high-velocity gunshot wounds. Abdominal paracentesis can be used in place of peritoneal lavage when the suspicion of intraabdominal hemorrhage is high and time is critical. Specific indications for peritoneal lavage and blunt trauma include a number of conditions such as a patient with major noncontiguous injuries, a patient with suspected intraabdominal injury in whom physical examination is unreliable or impossible due to the need for prolonged general anesthesia for another injury. Peritoneal lavage is not useful for patients with abdominal gunshot wounds; all of these patients require immediate laparotomy. When local examination of a stab wound suggests penetration to the anterior fascia and peritoneum, diagnostic peritoneal lavage may help discriminate between those with significant and insignificant injuries.

36. Physiologic responses to hypothermia include:

a. Tachycardia regardless of core temperature
b. Tachypnea regardless of core temperature
c. Pupillary dilatation and loss of cerebral autoregulation at temperatures below 26°C
d. A cardiac rhythm contraindicates cardiopulmonary resuscitation even in the absence of a palpable pulse
Answer: c, d

The physiologic response to hypothermia is one of transitional changes, with few exact temperature-dependent responses. Broadly speaking, the transition from a “safe zone” of hypothermia (where physiologic adaptations to heat loss are working) to a “danger zone” of hypothermia occurs between 33°C and 30°C. The cardiovascular response includes tachycardia followed by progressive bradycardia which starts at about 34°C , and which results in a 50% heart rate decrease at 28°C. Asystole occurs below 25°. Due to difficulty in palpating weak, bradycardic pulses in cold, stiff hypothermic patients, the presence of an organized rhythm should be taken as a sign of life that contraindicates CPR, despite the absence of a palpable pulse. Respiratory drive is increased during the early stages of hypothermia, but below 30°C progressive respiratory depression occurs, resulting in a decrease in minute ventilation.
The neurologic response to hypothermia is heralded by progressive loss of lucidity and deep tendon reflexes, and eventually flaccid muscular tone. Pupillary dilatation and loss of cerebral autoregulation occur at temperatures below 26°, and electroencephalography becomes silent at 19–20°. It is important, however, to remember that patients have been revived with core temperatures as low as 17°C, and therefore the saying “No one is dead until warm and dead”.

37. Which of the following statement(s) is/are true concerning the injury pattern in patients with blunt versus penetrating injuries?

a. Solid organs are most frequently injured following blunt trauma
b. The liver is the most frequently injured organ in both penetrating and blunt trauma
c. Major vascular injuries occur much more commonly in penetrating trauma than with blunt abdominal trauma
d. Injury patterns for blunt abdominal trauma in children are different than adults whereas with penetrating trauma no such difference exists
Answer: a, c, d

Most series list the spleen as the most commonly injured intraabdominal organ after blunt trauma. However, the means of diagnosis may affect this finding since small liver injuries, often detected only on CT scan of the abdomen, may go unreported while splenic injuries are likely to be clinically significant and require surgical intervention. Solid organs are most frequently injured from blunt trauma since the sudden application of pressure to the abdomen is more likely to rupture a solid organ than a hollow viscus, and this accounts for the greater incidence of solid organ injury. More elastic tissues of young people tolerate trauma better than those of older people, and this accounts, in part, for the differences in injuries between children and adults with blunt abdominal trauma. Major vascular injuries occur in over 10% of patients sustaining penetrating trauma but occur in only approximately 2% of patients with blunt trauma.

38. An 18-year-old male suffers a gunshot wound to the abdomen, resulting in multiple injuries to the small bowel and colon. Which of the following statement(s) is/are true concerning this patient’s perioperative management?

a. A multi-agent antibiotic regimen is indicated
b. Antibiotics should be continued postoperatively for at least 7 days
c. Laparotomy, as a diagnostic test for postoperative sepsis, should be considered
d. The incidence of postoperative wound or intraabdominal infection would be increased in association with a colon injury
Answer: d

Post-traumatic intraabdominal infection is almost always the result of gastrointestinal tract contamination. Penetrating trauma accounts for the largest proportion of these infections. Because of the higher bacterial counts, the colon is consistently associated with a higher incidence of infectious complications than isolated gastric, duodenal, or small bowel injuries. The precise incidence of intraabdominal or incisional wound infection after colonic injuries depends on factors present at the time of injury (blood loss, degree of contamination, and other associated injuries) and on whether the wound is closed or left open. The use of perioperative antibiotics for trauma has been investigated extensively. Most studies have demonstrated that single-agent cephalosporins are at least as effective as multi-agent regimens in retarding intraabdominal abscess or wound infections resulting from a variety of contaminated traumatic wounds.
Fever, leukocytosis, tachycardia, the development of a paralytic ileus, increased fluid requirements, and failure to wean from a mechanical ventilation may all represent warning signs of the development of intraabdominal infection. CT is the single most useful diagnostic tool in this clinical setting because it yields considerable information with regard to organ injury in the presence of intraabdominal abscesses or fluid collections. Laparotomy, as a diagnostic tool for unexplained sepsis, has a low-yield in critically ill trauma patients and should not be used routinely.

39. A middle-aged man is undergoing laparotomy for blunt abdominal trauma. The spleen and liver are both found to be injured. Which of the following statement(s) is/are true concerning the management of these injuries?

a. If the patient has multiple other abdominal injuries and hypotension, splenic salvage should not be attempted
b. The incidence of life-threatening sepsis in the adult following splenectomy is no greater than in the normal population
c. All liver injuries regardless of their depth require external drainage
d. The Pringle maneuver should control all bleeding from hepatic parenchymal vessels
e. If concern for a biliary fistula from the liver parenchyma exists, a T-tube should be placed even if the common bile duct is otherwise normal
Answer: a

Solid abdominal organs such as the liver and spleen, are most commonly injured during blunt abdominal trauma. The management of splenic trauma has been the subject of major reexamination in the last few decades. Historically, splenic injuries are routinely treated with splenectomy. With increased appreciation of the danger of post-splenectomy sepsis, splenic salvage procedures and nonoperative management of these injuries have become well accepted. This is particularly true in children. The incidence of post-splenectomy sepsis varies from 0.5% to as much as 12% to 15%, depending on the age and underlying disease. The incidence is inversely related to age and is higher with underlying hematologic disorders such as lymphoma or thalassemia. The incidence of life-threatening sepsis in adult trauma patients is low, but higher than in the normal population. Splenic salvage should not be attempted if the patient has protracted hypotension or other severe injuries or if undue delays are encountered in an attempt to repair the spleen.
Simple lacerations of the liver found at the time of surgery do not require drainage unless they are deep into the liver parenchyma, in which case they have a high probability of postoperative bile leakage. Biliary fistulas usually will close spontaneously, and major extrahepatic ductal injuries are rare. A T-tube placed in an otherwise normal common bile duct is inappropriate unless the extrahepatic biliary tree is injured. In the event that bleeding continues despite segmental ligation of parenchymal vessels, the structures of the porta hepatis should be compressed as a diagnostic maneuver (Pringle maneuver). If the bleeding stops, it is assumed to originate from the portal veins or hepatic artery. If the bleeding continues, it is presumed to arise principally from the hepatic veins or inferior vena cava.

40. Which of the following conclusions can be drawn from prospective randomized studies involving restoration of circulation in the field?

a. Pneumatic anti-shock garment is of benefit only in patients with a field blood pressure less than 50
b. Patients with major vascular injury should not receive intravenous fluid infusion until bleeding can be controlled in the operating room
c. Hypertonic saline, used as resuscitation fluid, provides no benefit to patients
d. Hypertonic saline has been shown to exacerbate bleeding and precipitate coagulopathy
Answer: a, b

The most common cause of death during the first hour after injury is hemorrhage. Therefore, after establishment of patent airway and adequate air exchange, the next priority is to support the circulation. The standard of care in the pre-hospital setting for hypotensive patients has been volume replacement and application of pneumatic anti-shock garment. In a recent large prospective randomized study, pneumatic anti-shock garments offered no survival advantage and actually increased mortality when used in patients with thoracic injuries. On the other hand, there was the suggestion that patients with a field blood pressure less than 50 mm Hg may benefit from this treatment. A second prospective study confirmed this result, indicating that the pneumatic anti-shock garment is of value to selected patients with field blood pressure less than 50 mm Hg. A recent clinical study has also demonstrated that internal hemorrhage from major vascular injuries should not be treated with intravenous fluid infusion until bleeding can be controlled in the operating room. In the hypotensive state, such major vascular injuries have a chance to clot and temporarily stop bleeding. But if intravenous volume restores blood pressure, the clot may dislodge and the rate of bleeding significantly increases. This may lead to both loss of oxygen carrying capacity and clotting factors, and ultimately exsanguination. Hypertonic saline restores intravascular volume and blood pressure to near normal very rapidly. The prospective randomized trial of normal saline versus hypertonic saline demonstrated a significant improvement in survival when the data were normalized to a select group of patients. There was no evidence that nontamponaded bleeding was exacerbated by the use of hypertonic saline despite the fact that blood pressure and intravascular volume increased.

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