When making rounds the nurse observes a client who is experiencing a seizure

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Answers

1. Answer D

The FAST (focused abdominal sonogram for trauma) scan is a bedside ultrasound that is used to detect free fluid in the peritoneal cavity, around the pericardium, and in the thorax. The four areas of focus in a FAST exam are the hepatorenal space (C), perisplenic space (E), pouch of Douglas/rectovesical pouch, and pericardial space. FAST exam cannot distinguish blood from ascites and/or enteric content, is unable to detect retroperitoneal bleeds (from, for instance, a pelvic fracture), and is often times limited by obesity. FAST exam will be able to detect bowel perforation if there is free fluid and only if the bowel is within the peritoneum (so would miss injuries to parts of the duodenum, posterior walls of cecum, sigmoid). For detecting pericardial effusion (A), the sensitivity approaches nearly 100 %. Although bilateral pneumothoraces may limit comparison of sides, a single pneumothorax (B) has a sensitivity of 95 % and specificity approaching 100 %.

2. Answer C

Penetrating neck trauma may result in injury to major blood vessels, the pharynx, esophagus, trachea, and/or cervical spine. Immediate surgical exploration (A) would be indicated if there were hard signs of vascular injury such as a pulsatile bleeding from the wound or rapidly expanding hematoma (the latter only after intubation {D} first to prevent airway compression). In the absence of hard signs of vascular injury, immediate surgical exploration is not necessary. Since physical examination is unreliable in terms of ruling out major injury, further imaging with CT angiogram (C) should be obtained. CT angiogram has largely replaced formal angiography (E) which was once considered the gold standard. Formal angiogram is invasive (requires a femoral artery catheterization), time consuming, costly, and is only useful to rule out arterial injuries. Wound closure (B) would only be appropriate for injuries that do not penetrate the platysma.

3. Answer B

In a patient presenting with hypotension, distended neck veins, and muffled heart sounds (Beck’s triad) following a stab wound to the chest, the most likely diagnosis is cardiac tamponade. The first sign in cardiac tamponade is impaired diastolic filling, which compromises cardiac output, and ultimately results in hypotension and distended neck veins (D, E). Electrical alternans (B) is characterized by varying alterations in the amplitude of the QRS complex between beats. It can occur in various other conditions and is not always present in patients with cardiac tamponade. Radiographic images are often negative initially, but some may develop the characteristic “water-bottle” shape later in the course of the disease (C).

4. Answer C

Many worried pregnant patients arrive to the ED following minor trauma. Most patients do not have any significant clinical findings. Her nonstress test showed a normal strip. The criteria to discharge pregnant patients following minor trauma include contractions no more than every 10 min, no vaginal bleeding, no abdominal pain, and a normal fetal heart tracing. This patient meets the discharge criteria and does not need to be monitored overnight (A). Biophysical profile (B) is indicated in patients with an abnormal nonstress test. CT of the abdomen (D) would be inappropriate in a pregnant patient because of the high radiation risk to the fetus. Although there have been no ill effects reported from MRI use during pregnancy, there are no indications to warrant MRI use in this patient (E).

5. Answer B

Do not forget the ABCs of trauma. The airway should always be addressed first in the primary survey. Burn victims are at high risk for respiratory compromise since the supraglottic airway is susceptible to direct thermal injury and does not have the protection afforded to the infraglottic airway via the reflexive closure of vocal cords to intense heat. Circumferential burns of the neck further increase the risk of respiratory compromise by way of inelastic, circumferential eschars that may constrict the airway. Endotracheal intubation should be performed for all burn patients with acute respiratory distress, circumferential neck burns, full-thickness burns of the face or orpharynx, supraglottic edema, and progressive hoarseness, stridor, or wheezing. Broad-spectrum antibiotics (A) are not routinely recommended for the management of burn victims. Burn patients are also at risk for severe intravascular collapse and require significant volume replacement with IV fluid resuscitation (C). However, this should be addressed after securing the airway. Premature ventricular contractions are usually benign (D). If the patient did not have indications for immediate intubation (circumferential neck burn), bronchoscopy (E) would be indicated in the presence of singed nasal hairs and carbonaceous sputum to determine the presence of thermal damage to the airway.

6. Answer A

High-energy rapid deceleration chest trauma is most commonly caused by a fall from greater than two stories or from a motor vehicle accident (e.g., steering wheel striking the chest). This mechanism of injury is known to cause aortic injuries which may lead to aortic transection, and ultimately death. Autopsy studies of aviation accidents demonstrate that more than 30 % of deaths are due to aortic transection. Overall, immediate mortality is greater than 70 %. The majority of patients die instantly of exsanguination. Of those who survive, 49 % will die within 24 h. Patients will present with a widened mediastinum, deviation of the trachea to the right, and left-sided hemothorax on chest radiographs. They may also have fractures of bones (e.g., first rib, sternum, scapula) that are uncommonly broken as high energy is required to break them. The aortic tear is usually at the ligamentum arteriosum, located just distal to the subclavian take off, as the aortic arch is relatively fixed to that point. CT angiogram can confirm the diagnosis, and definitive management includes operative repair. Although a ruptured spleen (D) can lead to significant blood loss, instant death is highly unlikely. The remaining choices (B, C, E) can all cause instant death, but they occur in less frequency than thoracic aortic transection with this mechanism of injury. Abdominal aortic transection is extremely rare following blunt trauma as it is more mobile than the thoracic aorta.

7. Answer D

A dislocated limb has the potential of compromising arterial blood flow. As such prompt reduction is essential. However, prior to reduction, the first step is to obtain a plain film of the limb to confirm the dislocation and to rule out associated fractures. Following reduction, a postreduction film is needed to confirm proper alignment. Fasciotomy (A) would be indicated if there is concern for compartment syndrome (pain in calf muscles on passive motion, tense swelling, paresthesias); however, reduction of a dislocated knee would still take priority. CT angiography (B) would be performed after reduction if there is concern for arterial injury (ankle-brachial index <0.9). Heparinization (C) would be initiated after limb ischemia is diagnosed (e.g., cold, pulseless limb). MRI of the knee (E) is seldom indicated in the acute setting for knee injuries.

8. Answer E

The diagnosis of isolated pancreatic injury is often delayed as it is notoriously known to be missed initially on CT. If there is no associated splenic injury to cause bleeding or bowel injury to cause peritonitis, initial physical examination findings may be unremarkable. In addition, a serum amylase level (A) is neither specific nor sensitive for pancreatic injury. However, if there is pancreatic duct disruption, the release of enzymes will eventually lead to symptoms as in the patient presented above. Surgery is recommended for such major injuries. Minor pancreatic injuries without pancreatic duct disruption can be managed nonoperatively. In such cases, ERCP (B) is more sensitive and specific than MRCP (D) for ductal injury. CT-guided drainage (C) will not address the underlying pancreatic injury and would not be appropriate for this patient.

9. Answer B

The patient has sustained a blunt injury to the carotid artery as evidenced by a dissection in the left internal carotid artery. Such an injury should be suspected whenever there is high-energy force to the head and/or neck. He is exhibiting evidence of Horner’s syndrome (ptosis, meiosis, anhidrosis), as sympathetic nerve fibers can be interrupted with carotid injury. A dissection is a partial-thickness tear in an artery that begins in the intima and extends into the media. It can narrow or occlude the lumen. Most blunt carotid injuries are managed nonoperatively with anticoagulation (provided there is no contraindication). Thus observation (E) alone would be inappropriate for such a patient. Since the dissection extends to the base of the skull, it would be impossible to access and repair through a standard neck incision (A). Conservative management using heparin (B) is the most appropriate option and has been shown to reduce or prevent cerebral infarction in patients with blunt carotid injury. Carotid stenting (C) has a risk of causing a stroke and would not be appropriate for a dissection that extends to the base of the skull. Thrombolysis (D) is contraindicated in a patient with a carotid dissection and in patients with trauma causing acute vascular injury.

10. Answer C

Immediate exploratory laparotomy is recommended in the majority of patients with a GSW to the abdomen, particularly if the patient is hemodynamically unstable, has evidence of peritonitis, or has bowel evisceration. However, cooperative patients with gunshot wounds (GSW) to the abdomen that are hemodynamically stable, with no evidence of peritonitis, are candidates for nonoperative management (NOM). They should be evaluated further for injuries requiring surgical repair with an abdominal CT scan. This approach may avoid an unnecessary exploratory laparotomy (B) that carries significant morbidity. CT scan should still be done even for patients with wounds that appear to only be superficial. If the CT scan is normal, the patient can be managed with serial physical exams (A) and serial laboratory exams (e.g., white blood count). NGT can help identify gastric injuries, while rectal examination can help identify rectal or colon penetration by the bullet. Though occasionally utilized for penetrating trauma, DPL and FAST (D, E) are more appropriate for blunt trauma.

11. Answer A

It is important to note that acute limb ischemia (in this instance due to embolization of atrial thrombus secondary to atrial fibrillation), followed by reperfusion, is a well-recognized risk for the subsequent development of compartment syndrome. Ischemia-reperfusion results in an increase in vascular permeability to plasma proteins and progressive interstitial edema. This leads to an increase in interstitial pressure. When interstitial pressure exceeds capillary perfusion pressure, muscle ischemia and necrosis ensue. It is important to note that palpable pulses do not rule out compartment syndrome. Treatment is an emergent 4-compartment fasciotomy. The lymph system (E) is not involved in the development of acute compartment syndrome. A recurrent embolus (B) would not be expected to present with a swollen leg and palpable distal pulses. DVT (C) can present with calf tenderness that is worsened with passive extension (Homan sign). However, the temporal relation to his presenting problem and the physical exam findings are more supportive for compartment syndrome. Atherosclerotic plaque (D) would be expected in a patient presenting with claudication secondary to peripheral arterial disease.

12. Answer D

Infections in burn patients can be problematic for multiple reasons. It may delay wound healing, encourages scarring, and can result in bacteremia which may lead to sepsis. Pseudomonas aeruginosa is a gram-negative bacillus and is considered to be the most common cause of infections in burn patients. Methicillin-resistant Staphylococcus aureus (A) is also commonly seen in burn patients and difficult to treat due to a large number of virulence factors. Streptococcus pyogenes (B) is more of a concern in pediatric burn patients because they may have colonization of Streptococcus pyogenes in their oropharynx. Streptococcus agalactiae (C) is not an organism thought to infect burn patients. This organism can colonize the genitourinary tract and be transmitted to the neonate during birth which may result in bacteremia, pneumonia, or meningitis. Fungal infections tend to occur in burn patients during the later stages of recovery because by this time the majority of bacteria have been eliminated by the use of antibiotics. The most common cause of fungal infection in burn patients is by Candida albicans (E).

13. Answer B

Duodenal injury following blunt abdominal trauma is rare. When it does occur, it is usually accompanied by other abdominal injuries. Isolated duodenal injuries are even more uncommon. In children, they have classically been reported following a direct blow to the epigastrium such as a bicycle handlebar injury. The retroperitoneal location of some portions of the duodenum may lead to a delay in diagnosis, as enteric contents spilling from the injury may not cause peritonitis. Contrast-enhanced CT scan of the abdomen can help confirm the diagnosis by detecting extravasation of oral contrast, the presence of retroperitoneal air, or a paraduodenal hematoma. Some duodenal injuries can be managed nonoperatively. Specifically, a duodenal wall hematoma, without contrast extravasation does not require surgery. On the other hand, the presence of contrast extravasation confirms a full-thickness injury that mandates exploratory laparotomy. Depending on the extent of injury, primary repair can be performed. Because of the close relationship of the duodenum to the pancreas and the bile duct, resection of the duodenum is often not possible. Upper endoscopy (D) would be contraindicated in the presence of bowel perforation. CT-guided drainage (E) will not address the underlying duodenal injury and would not be appropriate for this patient. Laparoscopy (A) would not likely be able to adequately assess and repair the duodenal injury.

14. Answer C

This patient has evidence of compartment syndrome that has led to muscle necrosis (as evidenced by high CPKs and hyperkalemia). Though compartment syndrome is mostly thought of as caused by severe bleeding after trauma, there are many other causes. In this case, it occurred secondary to prolonged compression of the forearm muscles due to his alcohol and drug binge. This resulted in ischemia, followed by reperfusion, and then swelling and death of the muscles. An alcohol binge can also lead to Saturday night palsy, a colloquial term referring to radial neuropathy from falling asleep with one’s arm hanging over a park bench (compressing the spiral groove which houses part of the radial nerve). Hyperkalemia is a known complication of muscle necrosis from compartment syndrome and can lead to peaked T waves, and if left untreated, fatal arrhythmias. Although all the options listed (A, B, D, E) are appropriate management options for hyperkalemia, calcium gluconate should be administered first to stabilize cardiac myocytes and prevent further damage, particularly because the electrolyte imbalance has already begun to affect the heart (e.g., peaked T waves).

15. Answer B

The key to the diagnosis is the history of trauma combined with the chest x-ray. On initial inspection, the chest x-ray could be confused with a hemothorax (D) or pneumonia (E). However, the presence of multiple air pockets within the left lung field indicates that there are loops of bowel in the left chest, likely due to a traumatic left-sided diaphragmatic hernia. Traumatic diaphragmatic hernia (TDH) can occur following blunt abdominal trauma secondary to a sudden increase in intra-abdominal pressure. Diagnosis is frequently delayed since patients may be asymptomatic immediately following the traumatic episode. The stomach and colon are the most frequently herniated structures. Patients with TDH can present with both GI and respiratory symptoms. Gastroenteritis (A) is unlikely to present with an increased respiratory rate or an abnormal chest x-ray. Following blunt trauma, patients can very rarely present with a delayed splenic rupture, and this could cause a reactive left pleural effusion. However, once again, this would not cause loops of the bowel in the chest.

16. Answer A

This patient has likely sustained damage to several structures of zone 1 of the neck. The first steps in management are always ABC. Given that there is an expanding hematoma and she is having difficulty speaking, there is concern that her airway is compromised, so she should be intubated. Since the apices of the lungs are contained within zone 1 of the neck, and she has absent breath sounds, she likely has a pneumothorax and will also need a chest tube (B). Duplex ultrasound of the carotid (C) is not necessary since there is a hard sign of vascular injury. The patient requires operative repair (D), but the airway should be protected first. This patient may have sustained esophageal injury that will require repair as well, but esophagoscopy (E) should not be performed since she has a hard sign of vascular injury.

17. Answer A

This patient has a penetrating abdominal wound which is concerning for an intraperitoneal injury. Immediate exploratory laparotomy is recommended in patients with a penetrating injury to the abdomen if the patient is hemodynamically unstable, has evidence of peritonitis, has bowel evisceration, or is uncooperative (e.g., intoxicated). Further work-up (B–E) can be considered for patients that are hemodynamically stable, with no evidence of peritonitis.

18. Answer C

The muscle is the first structure to be affected by ischemic changes in acute limb ischemia, and since it is the primary mass of the tissue in the extremity, the extent and duration of muscle damage are the most critical aspects of limb reperfusion syndrome and subsequent compartment syndrome. The muscle can be tolerant of ischemia for up to 4 h. Irreversible nerve damage (B) occurs after 8 h of ischemia. Fat (A) changes remain reversible for up to 13 h, the skin (D) up to 24 h, while the bone (E) damage does not typically occur until after 4 days of ischemia.

19. Answer E

Patients with severe burns are at increased risk of burn wound sepsis. This patient has hypothermia, leukocytosis, and tachycardia. Thus he meets the diagnostic criteria for systemic inflammatory response syndrome (SIRS). Patients must have two of the following four in order to be diagnosed with SIRS: fever of more than 100.4 °F or less than 96.8 °F, heart rate of more than 90, respiratory rate of more than 20, or white blood count of >12,000/μL or <4,000/μL. SIRS due to an infection is called sepsis and can manifest with confusion or altered levels of consciousness (i.e., end-organ damage). Burn patients in particular are susceptible to bacterial infections. Changes in the color of the burn wound (to red, brown, or black) should raise suspicion for wound sepsis. Intercompartmental fluid shifts (A), or third spacing, occur when fluid that accumulated in the interstitium of tissues during the postoperative period shifts back into the intravascular space, typically on postoperative day three. This will present with a patient that appears to be fluid overloaded. Tertiary corticoadrenal insufficiency (B) should always be on the differential for patients with long-term steroid use that develop hypotension. This occurs because of insufficient corticotropin-releasing hormone secretion by the hypothalamus. However, the risk is less in patients using topical steroids because of its decreased potency and limited systemic exposure. In addition, hypothermia would not be expected with adrenal insufficiency. Alcohol withdrawal (C) would be expected to begin within 24 h of the last drink (not 7 days later). It can present with a wide range of symptoms including tremulousness, insomnia, anxiety, diaphoresis, and autonomic hyperactivity. Burn patients are at risk of carbon monoxide poisoning (D), particularly when they are confined to a close space. However, carbon monoxide poisoning will present acutely (not 7 days later) with headaches, dizziness, and nausea.

20. Answer B

Patients with blunt chest trauma that present with persistent hypotension, tachycardia, and elevated JVP should be suspected of having an injury to the heart. Furthermore, this patient had a drop ≥10 mmHg in systolic blood pressure during inspiration (pulsus paradoxus) which supports a diagnosis of cardiac tamponade. Although cardiac tamponade classically causes a globular appearance of the heart on CXR, the cardiac silhouette may be normal. A lung contusion (C) would cause respiratory distress but not features of tamponade. An aortic transection (A) presents with a wide mediastinum and would not cause neck vein distention. Tension pneumothorax (D) may have distended neck veins, but the collapsed lung would be apparent on CXR combined with tracheal deviation. Diaphragmatic injury (D) can occur following blunt abdominal trauma and often present with GI and respiratory complaints though they may initially be asymptomatic.

21. Answer A

Hypotension after blunt trauma should be considered due to hemorrhage until proven otherwise. Head injury should not be considered the source of hypotension. The most likely sources of bleeding are the abdomen, pelvis, and chest. However, major chest bleeding has been ruled out by the negative CXR. In the stable patient, an abdominal CT (E) is the best test to rule out bleeding. However, the patient’s hemodynamic instability precludes such a study. FAST scan is the test of choice in the unstable patient, but its utility is often limited in obese patients because of poor image quality. In equivocal cases, the next best choice is to perform a DPL to detect free fluid in the peritoneum, which would be an indication for exploratory laparotomy. Proceeding directly to exploratory laparotomy (C) would be appropriate if the patient manifested peritoneal signs. However, his altered mental status precludes a proper physical examination. Pelvic bleeding is another potential source of bleeding, although pubic rami fractures rarely cause major bleeding (more likely with fractures of the posterior pelvis). If the DPL was negative, one would then pursue pelvic angiography (B) to rule out pelvic bleeding. Given the GCS of 10, a head CT (D) is indicated, but this would not take precedence over identifying the source of hemorrhagic shock first.

22. Answer C

The patient is displaying evidence of neurogenic shock with hypotension and an inappropriately normal heart rate (or bradycardia). Neurogenic shock is associated with a high cervical spinal cord injury (not thoracic spine injury {E}). Priapism (a sustained erection due to unopposed parasympathetic tone) is often a presenting sign of acute spinal cord injury. Neurogenic shock would be expected to present with a normal/high cardiac output (A), decreased SVR (B), and sympathetic blockade (D). Treatment is with intravenous fluids and if needed, pressor support (with an alpha agent for vasoconstriction).

23. Answer B

This patient has a dirty wound, but has likely had all three tetanus vaccinations. Based on the table below, the correct treatment is tetanus vaccination only. Antibiotics (E) are not indicated since the patient is not infected. Since this is a dirty wound, primary closure (D) may not be attempted in this case, and the wound may be packed instead (Table A.1).

24. Answer C

Children with supracondylar fractures are at risk for acute compartment syndrome. There are three mechanisms as to why this occurs: (1) the fracture is associated with an often unrecognized brachial artery injury that leads to ischemia in the compartments of the arm; (2) if the subsequent cast is placed too tightly, this may contribute to compartment syndrome; (3) initial bleeding and muscle damage/edema causes high pressures in the compartments of the arm leading to compartment syndrome. Compartment syndrome presents with the 6 Ps (pain, pallor, pulselessness, paresthesias, paralysis, and poikilothermia). Treatment is fasciotomy. Volkmann’s contracture is the manifestation of unrecognized and untreated compartment syndrome. This occurs because prolonged ischemia can lead to muscle death and subsequent fibrotic changes within the tissue. Volkmann’s contracture presents with a tense, painful, weak, and shortened forearm with a claw-like deformity of the hand. Nerve entrapment (A) is more likely to present acutely after the injury and will have deficits consistent with the distribution of a particular nerve. Suppurative tenosynovitis (B) is characterized by the four cardinal signs (Kanaval signs): flexor tendon sheath tenderness, fusiform swelling (sausage-shaped digits), pain with passive extension, and a semi-flexed posture of the involved digit. Complex regional pain syndrome (D) is a poorly understood phenomenon that occurs in patients that have had a crushing or soft tissue injury, typically to the distal extremities. They can present within days or months with intermittent pain, difficulty using the extremity, neglect-like symptoms, and rapid fatigability. An improperly reduced fracture would have been recognized earlier and corrected and would be unlikely to result in the deficits seen in this patient.

25. Answer E

Cutaneous squamous cell carcinoma arising from a chronic non-healing wound (such as a burn) is known as Marjolin’s ulcer. Although all the answer choices (A–D) are considered independent risk factors for skin cancer, chronic inflammation is the most important contributing factor in Marjolin’s ulcer and can be seen in burn wounds, scars, chronic ulcers, or sinus tracts. Carcinoma develops on average 20–30 years after the original burn. All chronic wounds that fail to heal after a long period should undergo a skin biopsy to rule out malignancy.

26. Answer B

This patient has a left-sided tension pneumothorax as confirmed by hypotension, distended neck veins, decreased breath sounds, and hyperresonant left chest. Immediate treatment is with needle thoracostomy, allowing for immediate thoracic decompression. This is preferred in the setting of a tension pneumothorax as it is faster than a chest tube, but provides only temporary relief. All these patients require a tube thoracostomy (chest tube) immediately following needle thoracostomy. Operative management (E) is not routinely indicated for patients with tension pneumothorax as needle decompression and subsequent tube thoracostomy are able to resolve most cases. If he had a significant hemothorax that continued to hemorrhage despite tube thoracostomy, surgical management could be considered as well as blood products (A). Tension pneumothorax is considered a clinical diagnosis, and confirmation with imaging (C, D) is not recommended as it delays definitive care in the unstable patient.

27. Answer B

Penetrating trauma to the extremities should be assessed for neurovascular injuries. Prompt surgical exploration (A) would be indicated if the patient had hard signs of vascular injury (e.g., pulsatile bleeding, expanding hematoma). In the absence of such signs, an ABI should be checked. If the ABI is <0.9, suspicion for an arterial injury is high, and as such, imaging with CT angiography is the most appropriate management option. Formal angiography (C) can be considered if CT results are equivocal. Observation would be appropriate if he had a normal ABI. Systemic heparinization is sometimes used during the course of arterial repair if the injury led to thrombosis and an interposition vein graft is used.

28. Answer E

This patient’s mechanism of injury and blood pressure drop are highly suggestive of hemorrhagic shock. Given that the patient responded well to IV fluids, it is appropriate to obtain CT imaging to look for the source of bleeding. If the source was intra-abdominal bleeding, the next step would be exploratory laparotomy (D). However, the CT indicates that the source is pelvic bleeding, likely from the pelvic fracture. Such bleeding is best managed via emergent pelvic angiography, which could be diagnostic and therapeutic (with embolization). MAST (A) suits were at one time popular as the compression was thought to tamponade bleeding. However, they have not been shown to be effective. External pelvic fixation (B) can reduce and stabilize fractures and thus lead to a slowing of bleeding, but is not considered as effective as angiographic emoblization. Open reduction, internal fixation (C) is the definitive treatment for a pelvic fracture. But given the technical difficulty and long length of such an operation, it is not recommended acutely, and especially not in someone who is actively bleeding. Pelvic packing is emerging as an alternative to angiography for pelvic bleeding.

29. Answer D

This patient presents with a right hemo- and pneumothorax, and tube thoracostomy was able to evacuate 500 cc of dark blood. The most appropriate next step in management is to perform a repeat chest x-ray to ensure that the tube thoracostomy is in the right position and that the hemo- and pneumothorax have resolved. Exploratory right thoracotomy (A) would be indicated only if the initial output after chest tube placement was >1,500 cc or if the patient continued to bleed briskly (>200 cc/h for 3 h). VATS (D) is indicated if the chest tube has inadequately drained the hemothorax. But such a residual hemothorax would be drained via VATS only after failure of a second chest tube and only after waiting a few days (not acutely). CT of the chest is generally not needed if the CXR shows that the hemothorax is resolved, and CT of the abdomen (E) is unnecessary at this time as the bullet entered just above the nipple (and thus above the diaphragm) and is visualized in the chest, thus sparing the abdominal cavity.

30. Answer C

This is concerning for a flail chest, most commonly caused by blunt trauma. Although the diagnosis is made clinically with a paradoxical inward motion of the chest wall during inspiration, it is supported by imaging studies demonstrating two or more consecutive ribs broken at two or more sites. The primary morbidity related to flail chest is the frequent underlying pulmonary contusion that accompanies it and compromises adequate respiration. Furthermore, severe pain may also affect respiration. Always start with the ABCs of trauma. The best course of management for the above patient (given the marked tachypnea and flail chest) is to first ensure an airway with endotracheal intubation. This can be followed by two large bore IVs and fluids (A). Blood products (D) may be needed if he does not respond to fluids and continues to remain hemodynamically unstable. There is no indication for a needle thoracostomy (B) or chest tube given that the breath sounds are equal. Chest tube (E) may be indicated if the patient had a concurrent pneumothorax on subsequent CXR.

31. Answer C

Acute carbon monoxide (CO) poisoning affects the organs with the highest oxygen demand first. Patients will present in the early stages with neurologic complaints (e.g., headaches, dizziness, confusion) and cardiac symptoms (e.g., chest pain, arrhythmias). All these patients should be started on 100 % oxygen via nonrebreather facemask. CO has nearly 250× more affinity for hemoglobin than oxygen. Thus the hemoglobin-oxygen dissociation curve shifts to the left, and more hemoglobin is bound by CO than it is by oxygen. This decreases both the hemoglobin saturation (of oxygen) and the oxygen content in the blood. The arterial partial pressure of oxygen is not affected in CO poisoning (B), and so a compensatory increased alveolar ventilation would not be expected (E). CO poisoning is not a consumptive or destructive process, and so hemoglobin would not be expected to change (A). Oxidized hemoglobin, also known as methemoglobin, has a higher affinity for cyanide, and so patients with cyanide poisoning are oftentimes given nitrates to induce the oxidization of hemoglobin to help bind the cyanide for renal clearance.

32. Answer E

Electrical burns are deceptive as at the skin level there may be a relatively minor burn wound. Yet, the electrical current can penetrate deep into the soft tissues, leading to extensive injury to the soft tissues and muscle. Thus electrical burns are associated with the development of compartment syndrome. The best indication for fasciotomy is in the presence of compartment syndrome. Choice E is the only choice in which there is an absolute indication for fasciotomy as the patient has clear evidence of compartment syndrome. Numbness of the first web space is the classic finding of anterior compartment syndrome, as the deep peroneal nerve travels within it, and it supplies sensation to the first web space. Options B, C, and D are relative indications for prophylactic fasciotomy, as they place the patient at increased risk of subsequently developing compartment syndrome, although prophylactic fasciotomies are controversial. A crush injury (A) by itself is not considered an indication for prophylactic fasciotomy.