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a thromboembolectomy and fasciotomy, he develops hypoxia with saturation of 87% and respiratory distress. An arterial blood gas shows: pH 7.47, paO2 = 50 mm Hg, HCO3 = 22 mmol/L, pCO2 = 30 mm Hg. Chest x‐ray shows patchy consolidations bilaterally and he reports fever prior to admission and that he works in a skilled nursing facility during the pandemic.Based on the above results, his A‐a gradient is (at sea level, water vapor pressure = 47 mm Hg):150 mm Hg10 mm Hg38 mm Hg50 mm Hg62 mm HgA‐a gradient equals PAO2−PaO2. His PaO2 from the ABG is 50. The PAO2 can be calculated from this equation: Therefore, A‐a gradient (PaO2−PAO2) = 62.5 mm Hg.Answer: EMarino P. The ICU Book , 3rd ed., Lippincott Williams & Wilkins, Philadelphia, PA, chapter 19 2007.
22 The patient above is placed on a nonrebreather mask with minimal improvement. What is the most likely etiology of the above patient’s respiratory failure and appropriate intervention?Pulmonary embolism, anticoagulation.Hyperventilation from anxiety, benzothiazines.COVID‐19 pneumonia, dexamethasone, and high‐flow nasal canula.Neuromuscular weakness, reversal of paralytic.Pulmonary edema, acute kidney injury from rhabdomyolysis.Hypoxemia occurs in four conditions: low inspired oxygen, shunt, V/Q mismatch, and hypoventilation.Hypoventilation would present with high CO2 and normal A‐a gradient. This could occur with oversedation, neuromuscular weakness, and residual anesthesia. Hyperventilation would cause tachypnea, low CO2, but not hypoxia, so A‐a gradient should be normal. Low inspired oxygen should have a low PO2 and normal gradient. An acute PE or asthma exacerbation presents with V/Q mismatch with elevated A‐a gradient and normal PCO2. It should correct with administration of oxygen. Shunting (pulmonary edema or pneumonia) has an elevated A‐a gradient that does not improve with oxygen administration. The patient is young for postoperative MI and has risk factors and a chest x‐ray consistent with COVID‐19 pneumonia, which could also increase his risk of thrombotic events since as an arterial thrombus.Answer: CWeinberger SE, Cockrill BA and Mande J. Principles of Pulmonary Medicine , 5th ed., W.B. Saunders, Philadelphia, PA, (2008).NIH COVID‐19 Treatment Guidelines. Therapeutic management of patients with COVID‐19. www.covid19treatmentguidelines.nih.gov/therapeutic‐management/ (accessed 15 December 20).
23 A 63‐year‐old patient with history of hypertension and type 2 diabetes presents with acute respiratory distress syndrome from pneumococcal pneumonia and is being managed by the ICU team for severe ARDS. After appropriate sedation and analgesia, which of the following is NOT an appropriate strategy for management?Low tidal volume ventilation (4–8ml/kg IBW).Prone positioning <6 hours/day.Use of recruitment maneuvers.Higher PEEP levels with plateau pressures <30 cm H2O.Very select use of high‐frequency oscillatory ventilation.Acute respiratory distress syndrome management guidelines target management with low tidal volume ventilation, low inspiratory pressures with plateau pressures <30 cm H20, high PEEP levels are better than low PEEP levels, and prone positioning for at least 12‐hour periods per day with improved mortality. Less than 6 hours of prone position per day would not be recommended as it is too short a time period.Answer: BFan E., Del Sorbo L, Goligher EC, et al. An Official American Thoracic Society/European Society of Intensive Care Medicine/Society of critical care medicine clinical practice guideline: mechanical ventilation in adult patients with acute respiratory distress syndrome. Am J Respir Crit Care Med. 2017; 195 9: 1253–1263. https://www.thoracic.org/statements/resources/cc/ards‐guidelines.pdf.
2 Cardiopulmonary Resuscitation, Oxygen Delivery and Shock
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