percentage of total circulating hemoglobin, increases until processed out through the renal system. Therefore, for this patient, aborting the procedure is not necessary. The desaturation is transient and not caused by mucus plugging, which may require bronchoscopy, pneumothorax, which would require tube thoracostomy, or significant atelectasis, which may require bag mask ventilation.Answer: EClifton J and Leikin JB . Methylene blue. Am J Ther. 2003; 10(4): 289–291.Rong LQ, Mauer E, Mustapich TL, et al. Characterization of the rapid drop in pulse oximetry reading after intraoperative administration of methylene blue in open thoracoabdominal aortic repairs. Anesth Analg. 2019; 129(5): 142–145.
4 A 65‐year‐old woman is in the post‐anesthesia care unit following elective inguinal hernia surgery. Shortly after arriving, she is noted to have increasing shortness of breath and wheezing requiring administration of a nebulized beta agonist. The patient has a known history of COPD. Which of the following pulmonary function test patterns would be expected in a patient with COPD?FEV1 decreased; FVC decreased/normal; FEV1/FVC ratio decreased.FEV1 increased; FVC decreased; FEV1/FVC ratio increased.FEV1 decreased/normal; FVC decreased; FEV1/FVC ratio normal.FEV1 increased; FVC increased; FEV1/FVC ratio increased.FEV1 decreased; FVC decreased; FEV1/FVC ratio decreased.Pulmonary function testing is often used in preoperative evaluation, particularly prior to thoracic procedures. These can be used, in addition to history and exam, to identify obstructive versus restrictive lung processes. Three of the important measures are the forced vital capacity (FVC) – the total volume forcefully expired after maximal inspiratory effort; forced expiratory volume in 1 second (FEV1) – the volume of air forcefully expired after maximal inspiratory effort in 1 second; the FEV1/FVC ratio. In evaluating spirometry results, first step is to interpret the FEV1/FVC ratio. If less than the lower limit of normal, an obstructive pattern is suspected. If greater than lower limit of normal, the FVC is evaluated and if less than lower limit of normal, a restrictive process is considered. Obstructive diseases include COPD, asthma, and emphysema while restrictive lung diseases include neuromuscular disorders and interstitial lung diseases.Answer: ABarreiro TJ and Perillo I . An approach to interpreting spirometry. Am Fam Physician. 2004; 69(5): 1107–1115.Pellegrino R, Viegi G, Brurasco V, et al. Interpretative strategies for lung function tests. Eur Respir J. 2005; 26:948–968.
5 You are caring for a patient in your SICU who is post total abdominal colectomy and end ileostomy. Ileostomy output has been in excess of 1.5L daily with concomitant acute kidney injury noted on basic metabolic panel with continued required resuscitation. Which of the following represents the primary relationships between alveolar pressure (PA), pulmonary arterial pressure (Pa), and pulmonary venous pressure (Pv) within the lung in a state of hypovolemia?Pa > Pv > PA and PA > Pv > PaPA > Pv > Pa and Pa > PA > PvPa > PA > Pv and PA > Pa > Pv PA > Pa > Pv and Pv > Pa > PAPa > PA > Pv and Pa > Pv > PAThe relationship between alveolar pressure, pulmonary arterial pressure, and pulmonary venous pressure represents the West zones of the lung. Zone 1, not seen in normal physiology, signifies alveolar dead space secondary to increased alveolar pressure causing arterial collapse (PA > Pa > Pv). Zone 2 represents pulsatile perfusion (Pa > PA > Pv) typically the upper portions of lung in a typical, upright person. Zone 3 represents the bulk of healthy lung tissue with continuous blood flow without extrinsic compression (Pa > Pv > PA). In a hypovolemic individual, as in this patient, decreased circulating volume converts Zone 3 tissue to Zone 1 and 2, increasing dead space.Answer: CWest JB and Dollery CT . Distribution of blood flow and the pressure‐flow relations of the whole lung. J Appl Physiol. 1965; 20(2): 175–183.For questions 7–10, use the following figure to match the clinical scenario to the appropriate flow volume loop:
6 A 42‐year‐old man presents to the ICU following intubation for COPD exacerbation.
7 An 18‐year‐old woman diagnosed on bronchoscopy with intratracheal lipoma.
8 A recovered COVID‐19 patient who develops tracheal stenosis following a 2 week intubation.
9 A 75‐year‐old male who undergoes emergent intubation following development of angioedema found to have R vocal cord paralysis.Flow volume loops involve plotting inspiratory and expiratory flow on the Y‐axis with volume on the X‐axis, ideally during maximally forced inspiratory and expiratory effort. Flow volume loops are component of the information presented on mechanical ventilators as well and can aid in the diagnosis of airway obstruction. The normal loop is seen in loop A above representing a complete inspiratory and expiratory breath. Loop B demonstrates variable extrathoracic obstruction with a flattening of the inspiratory component. This is due to a combination of atmospheric extraluminal pressure and negative intraluminal pressure exacerbating extrathoracic obstruction as in vocal cord dysfunction and mobile tumors such as lipoma. Intrathoracic variable obstruction, such as with bronchogenic cysts or intrathoracic tracheomalacia, is demonstrated by flattening of the expiratory component, as seen in loop C. Pleural pressure becomes positive relative to airway pressure exacerbating obstruction during expiration. Loop D demonstrates fixed airway obstruction, as with tracheal stenosis, causing flattening of both components of the loop. Finally, loop E demonstrates lower airway obstruction as seen in COPD and asthma. A scooped‐out appearance to the loop comes from premature airway closure as heterogeneity of flow in expiration, i.e., areas with higher elastic recoil and lower airway resistance empty faster than diseased areas.Answers: 6‐E, 7‐B, 8‐C, 9‐BLoutfi SA and Stoller JK . Flow‐volume loops. UpToDate. Retrieved November 16, 2020 from https://www.uptodate.com/contents/flow‐volume‐loops?search=flow%20volume%20loops&source=search_result&selectedTitle=1~59&usage_type=default&display_rank=1Pellegrino R, Viegi G, Brusasco V, et al. Interpretative strategies for lung function tests. Eur Respir J. 2005; 26(5): 948–968.
10 A 72‐year‐old woman is admitted to the trauma ICU after presentation following high‐speed MVC. A pulmonary artery catheter is placed given the patient’s refractory hypotension. Which of the following is consistent with cardiogenic shock?PCWP (mmHg)CO (L/min)SVR (dyne‐sec/cm5)MVO2 (%)A85120070B43180050C143180050D88120070E86180070Though used infrequently within the surgical ICU setting, the Swan‐Ganz catheter is a useful adjunct in the diagnosis of undifferentiated shock. Normal values obtained, as in option A, show a pulmonary capillary wedge pressure (PCWP) 8–12 mmHg, cardiac output (CO) 5–7 L/min, systemic vascular resistance (SVR) 900–1300dyne‐sec/cm5, and mixed venous oxygen (MVO2) approximately 65%. Option B indicates severe hypovolemic shock with decreased PCWP, decreased CO, increased SVR, and decreased MVO2. Option C indicates cardiogenic shock with increased PCWP, decreased CO, increased SVR, and decreased MVO2. Option D indicates distributive shock with normal PCWP, increased CO, decreased SVR, and increased MVO2. Option E indicates obstructive shock with normal PCWP, normal CO, increased SVR, and increased MVO2.Answer: CCecconi M, De Backer D, Antonelli M, et al. Consensus on circulatory shock and hemodynamic monitoring. Task force of the European Society of Intensive Care Medicine. Intensive Care Med. 2014; 40: 1795–1815.
11 A 73‐year‐old female with past medical history of significant peripheral vascular disease, hypertension, and diabetes is admitted to the ICU with significant hypotension following a myocardial infarction in PACU after undergoing EVAR of a 6 cm AAA. STAT echocardiogram shows right‐sided heart failure. Swan‐Ganz catheter is placed with PCWP of 10 mmHg. What is the next appropriate intervention?Inotrope initiation.Vasopressor initiation.Placement of intra‐aortic balloon pump.Volume resuscitation.Diuretic therapy.The initial treatment of choice following acute right heart failure following MI is fluid resuscitation until PCWP > 15 mmHg is reached. Following this, initiation of inotropes, such as dobutamine, is done. Diuretic therapy may play a role in normotensive individuals. Vasopressors may be used in hypotensive patients with the goal of increasing systemic vascular resistance without increasing pulmonary vascular resistance. Fluid resuscitation should be adequate before continuing to increase vasopressor use. The intra‐aortic balloon pump is used in left heart failure, not right heart failure.Answer: DVentetuolo CE and Klinger JR . Management of acute right ventricular failure in the intensive care unit. Ann Am Thorac Soc. 2014; 11(5): 811–822.
12 An 83‐year‐old woman with past medical history of significant peripheral vascular disease, ESRD on peritoneal dialysis admitted following below knee amputation for acute limb ischemia. You are called to bedside for patient’s mean arterial pressure of 55 mmHg. You note the systolic pressure is appropriate, but diastolic pressure remains