MED MISCCertified-in-NeuroCritical-Care-ABEM-(NCC)

Question: 710 A 55-year-old man, admitted with a Hunt and Hess grade 4aneurysmal subarachnoid hemorrhage (SAH), is now post bleed day5 with increasing Transcranial Doppler (TCD) velocities. Meanarterial pressure (MAP) is 76 mmHg on norepinephrine 12mcg/min, up from 5 mcg/min 24 hours earlier, intracranial pressure(ICP) is 12 mmHg, and heart rate (HR) is 110/min with sinusvolume control mechanical ventilation receiving 7 mL/kg tidalvolume (TV) with positive end-expiratory pressure (PEEP) of 10White blood cell (WBC) count is 11,000 with a new infiltrate onchest x-ray (CXR); and serum creatinine has increased to 1.5mg/dL. Fluid balance over the past 24 hours is 2 L positive withgood urine output. In addition to sending blood cultures, lactate, andstarting antibiotics, how can volume status be assessed to determinewhether additional fluid is needed for adequate resuscitation? A. Bolus 2 L normal saline (NS) over 2 hours and assess change in B. Perform a straight leg raise and assess for change in cardiac C. Place a Swan-Ganz catheter given the presence of shock and D. Measure inferior vena cava size change during inspiration and E. Insert arterial line and measure pulse pressure or stroke volume G. mmHArterial blood gas (ABG) reveals a PaO2/FiO2 ratio of 250. Answer: B Explanation: Our patient is in septic shock, which requires timely acquisition of cultures, lactic acid, initiating antibiotics, and fluid resuscitation. This question is focused on how to best determine whether a patient in shock has been adequately resuscitatedùa critical question, since too little fluid leads to inadequate preload, reduced cardiac output (CO) and oxygen delivery, and consequently tissue hypoperfusion. Conversely, excessive volume loading, without further increase in CO, would lead to hemodilution and tissue edema. Fluid overload has been associated with worse outcomes in critically ill patients, and current guidelines recommend frequent assessment for ongoing need for resuscitation prior to fluid administration. Fluid responsiveness can be assessed by several methods. Traditional static measures of cardiac preload, such as central venous pressure (CVP) and pulmonary capillary wedge pressure (PCWP) are unreliable for predicting fluid responsiveness. Dynamic measures of cardiac preload, such as stroke volume variation (SVV) and pulse pressure variability (PPV) require an arterial line, and are excellent measures of volume responsiveness in shock patients - with some notable exceptions: spontaneous respiration; tidal volume (TV) 8 mL/kg; PEEP 5; low lung compliance (i.e., ARDS); and when arrhythmias are present. Our patient was spontaneously breathing, limiting the diagnostic accuracy of SVV/PPV. Variation in inferior vena caval size during mechanical ventilation, as measured by echocardiography, is another means of assessing fluid responsiveness, but seems to be less sensitive and specific than SVV/PPV, with similar limitations. A third technique involves an ôautotransfusion,ö by passively raising the legs to 40 degrees in a supine patient, which has been shown to be a sensitive and specific assessment for volume responsiveness, potentially even in spontaneously breathing patients, during low-tidal ventilation, and with cardiac arrhythmia. Question: 711 An 18-year-old man admitted to the hospital with a gunshot woundto the head and intractable intracranial hypertension is being deescalatedfrom hyperosmolar therapy with hypertonic saline andpotassium is 2.0 mEq/L, despite having received approximately 120mEq of potassium chloride in replacement that day, and the urineoutput has been consistently greater than 200 mL/hour. Additionalpertinent labs include Na 153 mEq/L, Mg 1.5 mEq/L, and HCO3 20mEq/L. You notice a change on the telemetry monitor and order aabnormality? A. Acute myocardial infarction (MI) B. Acute pulmonary embolism C. Hypokalemia D. Acidosis E. Hypothermia G. stat ECWhat is the likely cause of this