CA-2 Questions JANUARY 22, 2020 

1) In which of the following clinical scenarios is the use of anesthetic agents to induce pharmacologic burst suppression MOST appropriate? A. Aortic root surgery with cerebral flow disruption B. Cerebral aneurysm surgery C. Cerebral protection following cardiac arrest D. Refractory status epilepticus 

 By inducing a largely electrically quiet brain state, the cerebral metabolic rate of oxygen (CMRO2) can be decreased by up to 50%. This is preferable to an entirely silent EEG as the presence of brief periods of activity allow for monitoring of the depth of anesthesia. By allowing for brief bursts of electrical activity, the provider is able to ensure that they are not providing an excessive amount of anesthetic agent to achieve a largely flat EEG.  Most appropriate in refractory status epilepticus 

2) A 22-year-old female arrives from the scene of a motor vehicle collision. A massive transfusion protocol is initiated and as part of it the patient will receive one unit of apheresis platelets. Which of the following is correct in regards to platelet transfusion? A. Platelets are suspended in normal saline B. Platelets should be kept refrigerated until infusion through an in-line warmer C. Platelets transfusion carry a lower risk of TRALI than PRBCs D. Platelet transfusions may lead to Rh sensitization 

 If RBCs contained in the platelet transfusion are Rh incompatible they may sensitize the host against Rh antigens. Most transfused platelets are Rh(D) positive, simply because most donors are. In the case of young Rh(D) negative women, consideration should be given to transfusing plateletsfrom Rh(D) negative donors, or to administering Rh immunoglobulin to prevent anti-D formation and the possibility of future hemolytic disease of the newborn.  Platelets are suspended in plasma  Platelets should not be refrigerated or warmed but rather given at room temperature  Platelets carry the highest risk of TRALI 

 3) Which of the following is most likely TRUE regarding spinal anesthesia? A) Blockade of parasympathetic efferents is the principal mechanism by which spinal anesthesia produces cardiac derangements B) Heart rate tends to increase due to the decrease in preload C) Hypotension is the result of venodilation without significant arterial dilation D) Intracardiac stretch receptors may lead to a significant decrease in heart rate 

 Bezhold-Jarish reflex = decrease in stimulation of cardiac stretch receptors results in bradycardia  Allows time for filling when venodilation occurs 

 4. A 55-year-old male with a history of insulin-dependent diabetes and hypertension is undergoing aortic valve replacement for aortic stenosis. He is successfully weaned from cardiopulmonary bypass but after administration of protamine, blood pressure falls to 65/42 mmHg, heart rate increases to 128 bpm, and pulmonary artery pressure decreases slightly to 16/9 mmHg. Transesophageal echocardiography shows poor ventricular filling and a more hyperdynamic heart than would otherwise be expected. Which of the following is the BEST drug to administer?  a. epinephrine  b. milrinone  c. isoproterenol  d. vasopressin 

 Three main types of protamine reactions 1) Brief hypotension (first line pressors) 2) Anaphylactoid reaction (epinephrine) 3) Severe pulmonary hypotension and right ventricular collapse (cardiopulmonary bypass) 

 5) Which of the following is least likely associated with a decrease in DLCO? A. Anemia B. Obesity C. Pulmonary emboli D. Lung resection 

 DLCO is reduced when there is less lung parenchyma to participate in gas exchange (lung resection, emphysema)  Reduced when there is less blood flow through lungs to participate in gas exchange (anemia, pulmonary embolism) 

 6) A 19-year old female with cystic fibrosis undergoes and emergent appendectomy. The anesthesiologist wants to evaluate the lung mechanics and applies an inspiratory hold. Which of the following is used to calculate the compliance value measured by this number? A) Cdynamic = VT / (Pplateau -PEEP) B) Cdynamic = VT / (PIP-PEEP) C) Cstatic = VT / (Pplateau -PEEP) D) Cstatic = VT / (PIP-PEEP) 

 In general, the equation for lung compliance is  Change in volume / change in pressure  Lung compliance is further subdivided into two categories  Static  compliance when gas flow has stopped  Measured during inspiratory pause  Calculated by taking tidal volume, plateau pressure and PEEP into account  Dynamic  Compliance during gas flow  Measured throughout  Calculated by taking tidal volume, peak pressure and PEEP into account 

 7) Which of the following evoked responses is the MOST sensitive to the effects of volatile anesthetics? A) Brainstem auditory evoked potentials B) Motor evoked potentials C) Somatosensory evoked potentials D) Visual evoked potentials 

 Most sensitive = Visual evoked potentials  Most resistant = brainstem auditory evoked potentials (that is why you have to be careful what you say in front of a “sleeping” patient.  Sensitivity = Motor > SSEP  Typically, intraoperative visual evoked potential monitoring is used for procedures that could place the visual system at risk.  Unfortunately, intraoperative monitoring of visual evoked potentials is the least popular of all types of evoked potential monitoring. Visual evoked potentials cannot be reliably interpreted. 

 8) Ventilation plays an important role in the speed of inhaled anesthetic uptake and induction (FA/FI). With which of the following agents does a high minute ventilation MOST improve the FA/FI? A) Desflurane B) Isoflurane C) Nitrous Oxide D) Sevoflurane 

 Agents with high blood:gas solubility (KB:G), such as isoflurane and halothane, are most affected by minute ventilation.  Recall that agents with low solubility have a more rapid onset and offset due to less blood and tissue uptake and more rapid equilibration of inspired and alveolar concentration (which equilibrates with the brain).  The rate of FA/FI is dependent on the alveolar concentration of inhaled anesthetic. The highly soluble agents are rapidly swept away into the blood once they reach the alveoli, which causes the alveolar concentration to fall. In order to replace the agent that leaves the alveoli, the patient requires a higher minute ventilation for delivery. 

 9) Regarding cardiopulmonary bypass, if pump outflow is occluded, excessive pressure can build proximal you the occlusion if which kind of pump is used? A) Neither roller nor centrifugal pump B) Roller pump C) Centrifugal pump D) Neither roller nor centrifugal pump 

 In general, 2 types of pumps are utilized for this purpose: roller pumps and centrifugal pumps.  Flow of roller pump is predictable and depends on revolutions per minute of the pump. Although retrograde flow is not possible, if there is outflow occlusion to the pump, excessive pressure can build, causing the tubing to rupture or the tubing connections to separate. Of course, there are safety checks in place to prevent this from occurring. 

 10) At which point of the ECG cycle should an intra-aortic balloon pump inflate? A. R Wave B. Q Wave C. P Wave D. T Wave 

 For an intra-aortic balloon pump to have optimal effect, the inflation and deflation must be timed appropriately to the patients cardiac cycle.  This may be done using the ECG tracing or the arterial waveform.  The IABP is triggered from the R wave of the ECG signal but the balloon inflation begins in the middle of the T wave with deflation prior to the end of the QRS complex.  The balloon should inflate at the beginning of diastole (noted as second diastolic augmentation at the point of the dicrotic notch on the arterial waveform). 

 11) A 14 year-old boy is undergoing multilevel posterior spinal fusion is maintained on sevoflurane 0.3 MAC, propofol at 125 mcg/kg/min, and fentanyl aiB bolides. Vital signs are stable with HR 78, BP 100/60 and SpO2 99% on 60% inspired oxygen. During pedicle screw placement, a reduction in somatosensory evokes potential (SSEP) amplitudes is noted. Which of the following interventions is most likely to increase SSEP amplitude? A) Discontinue sevoflurane and double the propofol infusion B) Replace the sevoflurane with an equivalent MAC of nitrous oxide C) Discontinue propofol infusion and double the sevoflurane MAC D) Reduce the propofol infusion and start a ketamine infusion 

 D  Neurological monitoring during scoliosis surgery may involve both somatosensory and motor evoked potentials.  In general MEPs are more sensitive to anesthetic agents than SSEPs.  Nitrous oxide strongly affects SSEPs with 50% inhale nitrous oxide interfering with the signal integrity more than a MAC equivalent dose of volatile agent.  Propofol produced better neurologic recording conditions than volatile agents. Infusion rates of 6 mg/kg/hr (100 mcg/kg/min) are acceptable, but higher rates do interfere with neuromonitoring in a dose-dependent manner.  Ketamine, on the other hand, increase SSEP amplitude.