Читать книгу Surgical Critical Care and Emergency Surgery - Группа авторов - Страница 9

Kevin W. Cahill, MD, Harsh Desai, MD, and Luis Cardenas, DO, PhD

Department of Surgery, Christiana Care Health Care System, Newark, DE, USA

1 A 72‐year‐old woman with a history of Child’s B cirrhosis and supraventricular tachycardia is in the ICU following laparotomy for strangulated ventral hernia. She begins to complain of rapid heartbeat and is noted to be in an irregular, wide‐complex ventricular tachycardia on EKG. She maintains pulse and adequate blood pressure. Which of the following is the best initial therapy to administer?Synchronized cardioversion.Adenosine 6 mg IV.Amiodarone 150 mg IV.Defibrillation.Vagal maneuvers.The 2020 ACLS guidelines differentiate between regular and irregular wide‐complex tachycardia with and without pulse. In this instance, the patient is in an irregular wide‐complex tachycardia, symptomatic, but stable as evidence by pulse and pressure. Given this hemodynamic stability, synchronized cardioversion and defibrillation are not the initial therapies (choices A, D). Adenosine and vagal maneuvers may be effective in regular ventricular tachycardia (choices B, E). Therefore, amiodarone is the best initial medication to administration often followed by infusion (choice C). Individuals with hemodynamically unstable ventricular tachycardia should not initially receive amiodarone. These individuals should be cardioverted. Amiodarone can be used regardless of the individual's underlying heart function and the type of ventricular tachycardia. It can be used in individuals with monomorphic ventricular tachycardia, but is contraindicated in individuals with polymorphic ventricular tachycardia as it is associated with prolonged QT intervals, which will be made worse with anti‐arrhythmic drugs. Amiodarone is categorized as a class III anti‐arrhythmic agent, and prolongs phase 3 of the cardiac action potential. Amiodarone slows conduction rate and prolongs the refractory period of the SA and AV nodes. It also prolongs the refractory periods of the ventricles, bundles of His, and the Purkinje fibers without exhibiting any effects on the conduction rate. Serious side effects include interstitial lung disease and liver dysfunction with elevated liver enzymes.Answer: CLittmann L, Olson EG, Gibbs MA . Initial evaluation and management of wide‐complex tachycardia: a simplified and practical approach. Am J Emerg Med. 2019; 37: 1340–1345.Panchal AR, Bartos JA, Cabanas JG et al. Part 3: Adult basic and advanced cardiac life support: 2020 American Heart Association guidelines for cardiopulmonary resuscitation and emergency cardiovascular care. Circulation. 2020; 142 (suppl 2): S366–S468.

2 Which of the following techniques has not been shown to be effective in airway management during cardiac arrest?Head tilt – chin liftJaw thrustCricoid pressureNasopharyngeal airwayOropharyngeal airwayOf the above maneuvers, cricoid pressure has not been shown to be effective during airway management in cardiopulmonary resuscitation. It may impede ventilation or placement of airway adjuncts such as a supraglottic airway as well as contribute to increased airway trauma. Jaw thrust is preferred in patients with suspected spinal injury. Nasopharyngeal and oropharyngeal airways are particularly useful in cases of facial trauma though care must be taken with possible basilar skull fractures.Answer: CCarauna E, Chevret S, Pirracchio R . Effect of cricoid pressure on laryngeal view during prehospital tracheal intubation: a propensity‐based analysis. Emerg Med J. 2017; 34 (3): 132–137.Panchal AR, Bartos JA, Cabanas JG et al. Part 3: Adult basic and advanced cardiac life support: 2020 American Heart Association guidelines for cardiopulmonary resuscitation and emergency cardiovascular care. Circulation. 2020; 142 (suppl 2): S366–S468.

3 In a patient experiencing PEA arrest, which of the following would not be a likely etiology?HypoglycemiaHypoxiaHypovolemiaHypokalemiaHypocalcemiaPulseless electrical activity is so named due to evidence of cardiac mechanical activity on echocardiogram or rhythm on EKG. The algorithm is similar to the asystole algorithm utilizing compressions and epinephrine. The traditional etiologies are described as “Hs” and “Ts.” The “Hs” include hypoglycemia, hypoxia, hyper/hypokalemia, hypovolemia, acidosis, and hypothermia. Hypocalcemia can present with muscular and neurologic symptoms such as perioral numbness, cramping, fatigue, seizures, and irritability. Hypocalcemia may also be associated with increased risk of arrhythmias, but is not typically considered high on the initial differential of PEA arrest. The “Ts” taught as etiologies include tension pneumothorax, cardiac tamponade, toxins, pulmonary thrombosis, or coronary thrombosis. Evaluation for pneumothorax or tamponade includes rapid bedside physical exam as well as point of care ultrasound for rule out. Ultrasound may also reveal signs of thrombosis with right ventricular enlargement or free‐floating thrombus.Answer: EAndersen LW, Holmberg MJ, Berg KM et al. In hospital cardiac arrest: a review. JAMA. 2019; 321 (12): 1200–1210.Panchal AR, Bartos JA, Cabanas JG et al. Part 3: Adult basic and advanced cardiac life support: 2020 American Heart Association guidelines for cardiopulmonary resuscitation and emergency cardiovascular care. Circulation. 2020; 142 (suppl 2): S366–S468.

4 Which of the following is the minimum chest compression fraction (defined as amount of time spent delivering chest compressions during CPR) shown to be associated with improved survival?0–20%21–40%41–60%61–80%81–100%Optimal outcomes have been demonstrated with minimal pauses between compressions for pulse checks and breaths given during high‐quality CPR. A compression fraction of at least 60% has been shown to be necessary for best outcomes. Animal studies previously conducted have demonstrated decreased coronary and cerebral perfusion when chest compressions are not being conducted resulting in worsened outcomes. Multiple retrospective analyses and cohort studies have resulted in many emergency agencies targeting a compression fraction of between 60 and 80% as a quality metric. This involves delivery of high‐quality compressions of appropriate depth, 2 inches, and rate, at least 100/min.Answer: DChristenson J, Andrusiek D, Everson‐Stewart S et al. Chest compression fraction determines survival in patients with out of hospital ventricular fibrillation. Circulation. 2009; 120: 1241–1247.Panchal AR, Bartos JA, Cabanas JG et al. Part 3: Adult basic and advanced cardiac life support: 2020 American Heart Association guidelines for cardiopulmonary resuscitation and emergency cardiovascular care. Circulation. 2020; 142 (suppl 2): S366–S468.

5 Which of the following is considered the highest predictor of survival for in‐ and out‐of‐hospital CPR?Age.Shockable rhythm.Arrest at home.Arrest at night vs during the day.Delayed EMS response time.On the whole, survivability is dependent on patient, system, event, and therapeutic factors. With increasing comorbidity and age, survivability decreases. System factors include time to arrival of EMS, time to initiation of CPR, and time to defibrillation. Event factors include preceding symptoms. Finally, therapeutic factors include availability of medications to treat suspected cause, time to ER, time to cath lab should it be required, etc. The greatest mortality risk with out of hospital cardiac arrest stems from unwitnessed arrests without bystander CPR often occurring at night in the elderly. Highest survivability stems from witnessed arrests with rapid initiation of bystander CPR and initial shockable rhythm, such as ventricular fibrillation.Answer: BMyat A, Song K‐J, Rea T . Out of hospital cardiac arrest: current concepts. Lancet. 2018; 391: 970–79.Navab E, Esmaelli M, Poorkhorshidi N et al. Predictors of out of hospital cardiac arrest outcomes in pre‐hospital settings; a retrospective cross‐sectional study. Arch Am Emerg Med. 2019; 7 (1): e36.

6 A 70‐year‐old man is 2 weeks status‐post laparoscopic sleeve gastrectomy and he undergoes witnessed cardiac arrest at home after complaint of new onset chest pain. Bystander CPR achieves ROSC after 10 minutes. He is now in the ICU, intubated, and on vasopressors for associated hypotension. Which of the following interventions has the strongest associated survival benefit in post‐arrest care according to current resuscitation guidelines?Maintain 100% FiO2.Pursuit of cardiac intervention when STEMI identified.Use of corticosteroids.Targeted temperature management to prevent fever.Seizure prophylaxis.If a cardiac cause is suspected, pursuit of cardiac intervention such as with percutaneous coronary intervention (PCI) is strongly recommended. Hyperoxygenation therapy, the use of corticosteroids, and seizure prophylaxis have thus far shown no survival benefit (choices A, C, and E). Finally, targeted temperature management is currently recommended for post‐arrest care with target of 32–36°C. This is based on several studies showing potential neurologic benefit. Preventing fever has not yet been proven to improve outcome though the 2020 AHA guideline (choice D). Ischemic heart disease is a major cause of out of hospital cardiac arrest. Among patients who had been successfully resuscitated after out of hospital cardiac arrest and had no signs of STEMI, immediate angiography was not found to be better than a strategy of delayed angiography with respect to overall survival at 90 days.Answer: BPanchal AR, Bartos JA, Cabanas JG et al. Part 3: Adult basic and advanced cardiac life support: 2020 American Heart Association guidelines for cardiopulmonary resuscitation and emergency cardiovascular care. Circulation. 2020; 142 (suppl 2): S366–S468.Yannapoulos D, Bartos JA, Aufderheide TP et al. The evolving role of the cardiac catherization laboratory in the management of patients with out of hospital cardiac arrest: a scientific statement from the American Heart Association. Circulation. 2019; 139 (12): e530–e552.Lemkes JS, Janssens GN, van der Hoeven NW et al. Coronary angiography after cardiac arrest without ST‐Segment elevation. April 11, 2019. N Engl J Med. 2019; 380: 1397–1407. DOI: https://doi.org/10.1056/NEJMoa1816897

7 A 35‐year‐old, 26 week pregnant woman has cardiac arrest with CPR ongoing in the ED. CPR has been ongoing for 5 minutes. Which of the following has been shown to provide greatest benefit for achieving ROSC?Corticosteroids.Targeted temperature management.Left lateral uterine displacement.Fetal monitoring.C‐section.In conditions of cardiac arrest after pregnancy, rapid delivery of the fetus, typically by C‐section, termed perimortem cesarean delivery (PMCD), has been shown to be associated with improved outcomes when CPR does not achieve ROSC. However, the decision must be made quickly as a review article states that if done within 10 minutes of arrest, it was associated with better maternal outcomes. It was also thought that it was beneficial to the mother in 31% of cases and was not harmful in any case. The review of the cases resulted in only 94 cases supporting that PMCD is rare. Corticosteroids have shown no benefit and targeted temperature management may be used after achievement of ROSC (choices A and B).The left lateral uterine displacement alleviates aortocaval compression in patients with hypotension, but delivery achieves this much more effectively (choice C). Fetal monitoring during maternal CPR is a distraction and may hinder care (choice D).Answer: EEinav S, Kaufman N, Sela HY . Maternal cardiac arrest and perimortem caesarean delivery: evidence or expert based? Resuscitation. 2012; 83 (10): 1191–1200.Panchal AR, Bartos JA, Cabanas JG et al. Part 3: Adult basic and advanced cardiac life support: 2020 American Heart Association guidelines for cardiopulmonary resuscitation and emergency cardiovascular care. Circulation. 2020; 142 (suppl 2): S366–S468.

8 Which of the following scenarios causes a shift of the oxygen dissociation curve to the left?A patient found unconscious in a basement apartment with malfunctioning heater.Patient with pneumonia and fever of 102°C.Patient with lactic acidosis from mesenteric ischemia.Patient with depressed mental status taking slow, shallow breaths.Patient returning from climbing Mt Everest where he had to stop and be treated for hypoxia after leaving base camp.Everest where he had to stop and be treated for hypoxia after leaving base camp. The oxygen–hemoglobin dissociation curve is sigmoidal in shape based on allosteric interactions of each globin monomer binding oxygen. A shift to the right indicates decreased affinity favoring unloading of oxygen while a shift to the left achieves the opposite effect. The strength by which oxygen binds to hemoglobin is affected by several factors and can be represented as a shift to the left or right in the oxygen dissociation curve. A rightward shift of the curve indicates that hemoglobin has a decreased affinity for oxygen, thus, oxygen actively unloads. A shift to the left indicates increased hemoglobin affinity for oxygen and an increased reluctance to release oxygen. Several physiologic factors are responsible for shifting the curve left or right, such as pH, carbon dioxide (CO2), temperature, and 2,3‐Disphosphoglycerate. Carbon monoxide exposure, as can be seen in enclosed spaces with a malfunctioning heater, can result in a leftward shift. If the patient was hypothermic or alkalotic, these conditions would also shift it toward the left.Answer: AWoodson, RD . Physiologic significance of oxygen dissociation curve shifts. Crit Care Med. 1979; 7 (9): 368–373.

9 You are caring for a patient in the SICU, currently intubated after undergoing left upper lobectomy for tumor. Patient’s current hemoglobin is 10 g/dL, oxygen saturation 95%, and PaO2 of 92 mmHg. What is the expected oxygen content (CaO2)?0.9 mL/dL9 mL/dL13 mL/dL21 mL/dL140 mL/dLBlood oxygen content is based on the following formula influenced by oxygen saturation, partial pressure of arterial oxygen, and patient’s hemoglobin: The single biggest factor for oxygen content is hemoglobin. Doubling of hemoglobin would double the oxygen content. Increasing the partial pressure of oxygen from 60 mmHg to 100 would increase saturation from 90 to 100% and would not be a large change in content. The doubling of partial pressure of oxygen from 60 mmHg to 120 mmHg would still only increase the content by 10% as the dissolved amount of oxygen in plasma is negated by the factor of 0.003. The constant of 1.34 is the amount of oxygen that one gram of hemoglobin carries at 1 atmosphere of pressure.Answer: CCrocetti J, Diaz‐Abad M, Krachman SL . Oxygen content, delivery, and uptake. In GJ Criner, RE Barnette, GE D’Alonzo (Eds), Critical Care Study Guide. New York: Springer, 2010.

10 Changes in which of the following components is the most influential in increasing oxygen delivery?Cardiac output.Hemoglobin level.Oxygen saturation.Oxygen dissolved in blood.Systemic vascular resistance.As described in the question above, oxygen content is influenced by hemoglobin, oxygen saturation, and partial pressure of arterial oxygen. Of these, hemoglobin level, which has the greatest impact on oxygen content through binding, has the greatest impact on oxygen available to deliver to tissues. Arterial oxygen saturation and cardiac output are additional important factors in ensuring adequate oxygen delivery. Increased cardiac output as a compensatory mechanism can carry more oxygenated blood for delivery. Improved oxygen saturations ensure appropriate oxygen availability for hemoglobin binding. Changes in vascular resistance can influence oxygen diffusion. The least influential of the above choices given, the minimal contribution it makes to available oxygen, is partial pressure of arterial oxygen i.e. dissolved oxygen.Answer: BMarino P . The ICU Book , 4th edn. Philadelphia: Lippincott Williams & Wilkins, 2007.

11 You are called to the PACU to evaluate a 64‐year‐old man with a history of metastatic lung cancer now s/p video‐assisted thoracoscopic resection of the left upper lobe. His heart rate is 110 beats/min, blood pressure 70/42 mm Hg. He appears tachypneic. On examination, he is cool and clammy, with evidence of peripheral cyanosis and prominent jugular venous distension. Anesthesia has successfully placed an arterial line and initiated several fluid boluses while awaiting your arrival; however, there has been no significant improvement in his hemodynamics. You note that his systolic blood pressure on the arterial line appears to decrease by at least 10 mmHg during respiration. While you prepare the appropriate intervention, what would be the best next step to help confirm the likely diagnosis?Chest X‐rayCT angiogramCBCEKGTransthoracic echocardiogramThis patient is exhibiting signs of cardiac tamponade, with evidence of pulsus paradoxus, jugular venous distension, and hypotension. The primary tool for diagnosis of cardiac tamponade is Doppler echocardiography, which in the presence of tamponade typically shows a circumferential pericardial fluid layer and compressed chambers with high ventricular ejection fractions. On inspiration, both the ventricular and atrial septa move leftward and reverse on expiration, due to the fixed pericardial volume. Right ventricular collapse is typically less sensitive but more specific for tamponade. The inferior vena cava is typically dilated with minimal respiratory variation. CT angiogram may demonstrate pericardial effusion, distension of the superior and inferior vena cavae, and reflux of contrast material into the azygos vein and inferior vena cava. However, these represent static images rather than the dynamic information presented by echocardiography. Chest x‐ray may demonstrate an enlarged cardiac silhouette but is particularly unreliable in early/acute tamponade (choice A). Additionally, obtaining a CT scan is typically not portable, requiring transporting a hemodynamically unstable patient to obtain the study (choice B). A CBC would be of little use to obtaining this diagnosis (choice C). EKG may show evidence of pericarditis or electrical alternans but is unreliable in the diagnosis of tamponade (choice D).Answer: ESpodick DH . Acute cardiac tamponade. N Engl J Med. 2003; 349 (7): 684–90. doi: https://doi.org/10.1056/NEJMra022643. PMID: 12917306.

12 A 27‐year‐old man presents after jumping from a diving board and striking the bottom of a pool with his upper body. On presentation, he has no sensation or motor strength of his lower extremities. On examination, he appears flaccid and you cannot elicit spinal reflexes. His heart rate is 54 beats/min, blood pressure 90/54, and respiratory rate 18. Despite appropriate fluid resuscitation, he remains hypotensive, though you identify no evidence of ongoing hemorrhage. What type of shock does this likely represent?ObstructiveDistributiveCardiogenicHypovolemicAnaphylactic This patient demonstrates bradycardia, hypotension, and neurologic deficits in the setting of possible cervical or high thoracic spine trauma, suggesting he may have a component of neurogenic shock. This shock is a result of spinal cord injury with sudden loss of sympathetic tone with preserved parasympathetic activity and autonomic instability, leading to bradycardia and hypotension. These changes are typically seen with an injury to the spinal cord above T6. Disruption of the sympathetic division of the autonomic nervous system affects three areas of the cardiovascular system: coronary blood flow, cardiac contractility, and heart rate. There is systemic hypotension due to a decrease in sympathetic fiber‐mediated arterial and venous vascular resistance, along with venous pooling and loss of preload, with or without bradycardia. The bradycardia is often exacerbated by suctioning, defecation, turning, and hypoxia. The hypotension places patients at increased risk of secondary spinal cord ischemia due to impairment of autoregulation. With preserved parasympathetic activity, this translates clinically into bradycardia (and possibly other cardiac arrhythmias) in the setting of profound hypotension. Trauma patients are hypotensive as a result of blood loss or intravascular hypovolemia but will mount an appropriate tachycardic response. Blood loss must be ruled out and treated appropriately before assuming that hypotension is due solely to spinal cord injury. It is common to have both blood loss and spinal cord injury. Initial management is composed of volume resuscitation to account for the increased intravascular space secondary to increased vasodilation, as well as vasopressors for blood pressure control. In addition to pressor support, chronotropic and inotropic support may be necessary. Norepinephrine is started initially but in refractory cases, epinephrine and vasopressin infusions may be required. Bradycardia usually responds to atropine and glycopyrrolate but in severe cases, dopamine infusion is required. When blood loss is a part of the presentation, volume resuscitation should be with blood products and not crystalloids. Spinal shock is often confused with neurogenic shock. Spinal shock, on the other hand, refers to loss of all sensation below the level of injury and is not circulatory in nature. Both may, however, coexist in a patient.Answer: BStein DM, Knight WA . Emergency neurological life support: traumatic spine injury. Neurocrit Care. 2017; 27 (Suppl 1): 170–180.Phillips AA, Krassioukov AV . Contemporary cardiovascular concerns after spinal cord injury: mechanisms, maladaptations, and management. J Neurotrauma. 2015; 32 (24): 1927–42. doi: https://doi.org/10.1089/neu.2015.3903. Epub 2015 Sep 1. PMID: 25962761.

13 Shock is defined as:Blood pressure less than 90 mm Hg.Heart rate greater than 140 beats/min.Urine output less than 0.5 ml/kg/hr.Inadequate perfusion to meet end organ metabolic needs.All of the above.Shock is defined by some as inadequate perfusion to meet end organ metabolic needs. Tissue and cellular hypoxia can be due to inadequate delivery, increased consumption, inadequate utilization, or a combination of these states. Although this is often reflected in hemodynamic changes such as hypotension, tachycardia, or oliguria, these are not sufficient criteria alone to diagnosis a patient as being in shock. A patient may present hypertensive, normotensive, or hypotensive. Conditions such as neurogenic shock may result in a patient with bradycardia despite inadequate perfusion. Shock can be further differentiated into hypovolemic, cardiogenic, obstructive, or restrictive (vasodilatory/distributive). Causes of obstructive shock include pulmonary embolism, tension pneumothorax, and pericardial tamponade. Causes of obstructive shock typically lead to decreased cardiac output and are sometimes included into the cardiogenic shock category. Identification of these sub categories of shock is crucial to guiding therapeutic intervention.Answer: DKislitsina ON, Rich JD, Wilcox JE et al. Shock ‐ classification and pathophysiological principles of therapeutics. Curr Cardiol Rev. 2019; 15 (2): 102–113. doi: https://doi.org/10.2174/1573403X15666181212125024. PMID: 30543176; PMCID: PMC6520577.Vincent JL, De Backer D . Circulatory shock. N Engl J Med. 2013; 369: 1726.

14 A 53‐year‐old woman with a history of ulcerative colitis controlled with 50 mg of oral prednisone daily undergoes a laparoscopic converted to open colectomy. Intra‐operatively there are no complications noted and she receives appropriate fluid resuscitation. However, post‐operatively she is noted to be febrile and hypotensive. This hypotension is refractory to additional fluid boluses or multiple vasopressors. On physical examination, her abdomen does not appear distended and she is appropriately tender. What would be the best next step in management of this patient?Additional fluid boluses.Adding on an additional vasopressor.Return to the operating room for exploration.Administer stress dose hydrocortisone.Begin broad‐spectrum antibiotics.This patient with a history of chronic adrenal suppression due to daily prednisone use presents with signs and symptoms consistent with an adrenal crisis. These events are typically brought on by an inability for the body to mount an appropriate response to an insult by generating endogenous cortisol secondary to chronic adrenal suppression. Unless administered appropriate exogenous glucocorticoids, they may exhibit evidence of hypotension refractory to typical interventions, abdominal pain, nausea/vomiting, and confusion. Additional fluid boluses or adding an additional vasopressor would not address the underlying pathology and has already been described as unsuccessful in this vignette (choices A, B). Initiating broad‐spectrum antibiotics similarly does not address the underlying issue and would have no impact on this patient’s hemodynamics (choice E). Septic shock would most likely develop later and not immediately. While a hypotensive patient post‐operatively may be due to blood loss and ultimately require return to the operating room for exploration, in this case, failure to recognize the underlying adrenal crisis would result in unnecessary re‐exploration (choice C).Answer: DRushworth RL, Torpy DJ, Falhammar H . Adrenal Crisis. N Engl J Med. 2019; 381 (9): 852–861. doi: https://doi.org/10.1056/NEJMra1807486. PMID: 31461595.

15 A 71‐year‐old patient has acute, non‐perforated appendicitis. His BMI is 27 and otherwise healthy. Intra‐operatively you begin with Veress needle insertion into the abdomen and begin to establish pneumoperitoneum with high flow rates. Your anesthesiologist immediately notes a marked decrease in the patient’s end‐tidal carbon dioxide and oxygen saturations as well as new onset tachycardia. You halt insufflation but the patient quickly becomes hemodynamically unstable. What is your best step to address the underlying pathology?Convert to open.Place the patient in steep Trendelenburg and place a central line for therapeutic intervention.Administer fluid bolus.Start vasopressors.Abort the procedure and transfer the patient to the ICU.This patient is demonstrating evidence of possible air embolism secondary to intravascular insufflation. The primary goal in this case is to prevent further gas entry into the venous system and reduce the amount of gas trapped in the heart. Placing the patient in Trendelenburg position maximizes blood flow to the brain and theoretically relieves right‐sided heart airlock as well as prevent gas entry into the pulmonary artery. In a patient who is hemodynamically unstable secondary to an air embolism, a central line should be placed into the right atrium and attempts made to withdraw air from the right side of the heart. Converting to open would not address the underlying issue (choice A). Initiating fluids or vasopressors would briefly temporize the patient but would not address the underlying pathology (choices C, D). Aborting the procedure and taking a hemodynamically unstable patient to the ICU would not be correct as the underlying pathology should be addressed prior to leaving the operating room (choice E).Answer: BSandadi S, Johannigman JA, Wong VL et al. Recognition and management of major vessel injury during laparoscopy. J Minim Invasive Gynecol. 2010; 17 (6): 692–702. doi: https://doi.org/10.1016/j.jmig.2010.06.005. Epub 2010 Jul 24. PMID: 20656569.

16 A 32‐year‐old healthy man was passed out in a workplace fire but had minimal burns to the right hand. Given suspected inhalation injury, you take care to establish a definitive airway and transfer the patient to the ICU for additional monitoring. The patient is initially tachycardic and hypertensive but shortly thereafter develops bradycardia, hypotension, and cardiac dysrhythmias. On physical examination, his skin appears flushed with a cherry‐red color. Labwork reveals a marked metabolic acidosis on arterial blood gas and serum lactate is 9 mmol/L. His carboxyhemoglobin level is normal. Which of the following would be most effective in addressing his underlying pathology? Aggressive fluid resuscitationAdministration of hydroxocobalaminVasopressor supportDiuresisContinue supportive careThis patient is showing evidence of possible cyanide poisoning with evidence of cardiovascular instability, marked metabolic acidosis, and classic “cherry‐red” skin color. Although present in only a minority of patients, this finding is a result of impaired tissue oxygen utilization, resulting in high venous oxyhemoglobin concentration, and bright red appearance of the blood. Hydroxocobalamin is a precursor of Vitamin B12 that directly binds to intra‐cellular cyanide, forming cyanocobalamin. This molecule is then readily excreted in the urine. This treatment acts rapidly, does not affect tissue oxygenation, and is relatively safe, making it a first‐line agent for cyanide poisoning. The other answer questions do not address what is driving the patient’s underlying pathology.Answer: BHendry‐Hofer TB, Ng PC, Witeof AE et al. A review on ingested cyanide: risks, clinical presentation, diagnostics, and treatment challenges. J Med Toxicol. 2019; 15: 128.

17 A 37‐year‐old patient is admitted to the floor after suffering a femur fracture during a MVC. While he is stable over the next 24 hours, he shortly thereafter develops a new petechial rash on the non‐dependent portions of his body, becomes hypotensive, confused, tachypneic, and is hypoxic on pulse oximetry. A chest x‐ray is obtained but appears normal. A CT angiogram of the chest does not demonstrate any evidence of pulmonary thromboembolism. What would be the next step in management?Supportive care with fluid resuscitation and oxygenationIntravascular tPA lytic therapyBroad‐spectrum antibioticsVasopressorsECMOThis patient is showing evidence of possible fat‐embolism syndrome. This is a rare entity that can be encountered in patients 24–72 hours after an initial insult (long bone fracture in this patient). The triad of hypoxemia, neurologic abnormalities, and petechial rash is classic for fat‐embolism syndrome, though non‐specific. Fat embolism can also present with thrombocytopenia and this may help make a diagnosis. However, it remains a diagnosis of exclusion, primarily made clinically. Initial assessment is performed to exclude alternative diagnoses such as pulmonary embolism. There is no definitive treatment and therapy is primarily supportive while awaiting resolution. There is no role for intravascular lytic therapy or broad‐spectrum antibiotics (choices B, C). While vasopressors and invasive ventilator support such as ECMO may be necessary in patients with refractory shock, they are not the initial step in management (choices D, E).Answer: AStein PD, Yaekoub AY, Matta F et al. Fat embolism syndrome. Am J Med Sci. 2008; 336: 472.

18 A 54‐year‐old patient with a history of diabetes mellitus on home metformin presents to your emergency department with shortness of breath, productive cough, and fever. On imaging, he is found to have a right lower lobe opacity consistent with pneumonia. He is hemodynamically stable but blood work is noted to have a lactic acidemia of 4 and his glucose is elevated to 300. His CBC is within normal limits and an EKG is normal. He is mentating well, making appropriate urine without evidence of tissue hypoperfusion. What best describes the patient’s lactic academia?Type A lactic acidosisType B lactic acidosisSeptic shockHemorrhagic shockCardiac failureThis patient is showing evidence of lactic acidosis in the absence of systemic hypoperfusion. Type A lactic acidosis is typically related to hypoperfusion secondary to hypovolemia, cardiac failure, sepsis, or cardiopulmonary arrest. Type B lactic acidosis occurs when there is no evidence of systemic hypoperfusion and may be related to impaired cellular metabolism (choice B). Both metformin use and diabetes mellitus have been implicated as associated with Type B lactic acidosis. This patient is showing no signs of septic, hemorrhagic, or cardiogenic shock (choices C, D, E).Answer: B