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88 Cards in this Set
- Front
- Back
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Patient gets sodium nitroprusside infusion, develops SpO2 85%: Cause?
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Methemoglobinemia (SpO2 falsely stuck at 85%)
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Why does sodium nitroprusside cause met-Hb? |
Metabolism of nitroprusside requires conversion of Oxy-Hb (Fe2+) to methemoglobin (Fe3+) |
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What is closing capacity? |
Lung volume at which small-airway (non-cartilagenous) closure begins to occur |
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Why do you want to maximize FRC preoperatively?
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Ensure that it is greater than closing volume to prevent atelectasis
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Patient with history of previous MI (12 mo ago): most likely to develop post-op MI when?
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3 days
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BMI formula?
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Weight (kg) divided by height (m) squared
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Normal FEV1/FVC ratio?
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80%
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DC cardioversion is not indicated in which unstable tachycardia? |
MAT |
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During the first minute of apnea, how much will PaCO2 rise? (mmHg)
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6
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During the second minute onwards of apnea, how much will PaCO2 rise? (mmHg)
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3
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What is the O2 requirement of an adult? (mL/kg/min) |
4 mL/kg/min |
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What is the O2 requirement of a neonate? (mL/kg)
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8
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FRC is a combination of what lung volumes?
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Residual Volume + Expiratory Reserve Volume
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What is the VD/VT equation? What does it measure?
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Dead Space: (PaCO2 - PECO2)/PaCO2
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What is the formula for oxygen content? |
(1.36 * Hb * SaO2) + (0.003 * PaO2) |
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1 mmHg increase in PaCO2 = ? increase in minute ventilation?
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3 L/min
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What is the P50 for normal adult hemoglobin? (mmHg)
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26
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What is the P90 for normal adult hemoglobin? (mmHg) |
60 |
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What is the P50 for sickle cell hemoglobin (HbS)? (mmHg)
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31
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How does sepsis affect MvO2? Why? |
Increases MvO2 (decreased oxygen consumption) due to maldistribution of perfusion |
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What is normal vital capacity? (mL/kg)
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60
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How does CO poisoning affect PaO2?
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No effect
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How does CO poisoning affect hemoglobin-dissociation curve?
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Left shift and decreased plateau value
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How does CO poisoning cause acidosis?
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Lactic acidosis due to decreased oxygen delivery to tissues
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How do volatile anesthetics affect central and peripheral chemoreceptors for ventilation? |
PERIPHERAL chemoreceptors: decrease ventilatory response. CENTRAL chemoreceptors: no effect |
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How much will pH change with acute change of PaCO2?
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0.08 decrease in pH with 10 mmHg increase in PaCO2
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How much will HCO3 decrease with a chronic decrease in PaCO2?
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5 mEq for every 10 mmHg drop in PaCO2
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Vasopressin infusion dosage?
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0.01-0.04 units/min (not weight based)
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What is the time-window for DC cardioversion of stable atrial fibrillation? Why?
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< 48 hours; risk of emoblic events after
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PaO2 is the highest at the lung: apex or base? Why? |
PaO2 highest at lung apex because there is the least amount of shunting here (mostly dead space) |
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PaCO2 is the highest at the lung apex or base? Why?
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PaCO2 highest at the lung base because you have more perfusion than ventilation (shunt) and cannot blow off CO2
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Which acid-base disturbance is the least compensated? Why?
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Metabolis alkalosis is least compensated by respiratory acidosis (hypoventilation) because you can't hypoventilate enough
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What is the alveolar gas equation?
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[ FiO2 * (atmospheric pressure - water vapor pressure) ] - [ PaCO2 / RQ ]
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What is respiratory quotient (RQ)? |
Volume of expired CO2 divided by volume of oxygen consumed |
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What is the normal range of RQ?
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0.7 - 1
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What does RQ = 1 indicate?
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Pure carbohydrate metabolism
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What does RQ = 0.7 indicate?
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Pure fat metabolism
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What is the best VENOUS location to estimate arterial O2?
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Vein on posterior surface of warmed hand because of minimal extraction of O2 here
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Which PFT is least dependent on patient effort?
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FEF 25%-75%
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What is the shunt equation?
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Qs/Qt = (C_alv_cap_O2 - C_a_O2) / (C_alv_cap_o2 - C_v_O2)
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What is the approx. numerical relationship between A-a gradient and shunt fraction?
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Every 20 mmHg increase in A-a gradient = 1% shunt
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Which IV anesthetic does not affect respiratory drive?
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Ketamine
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Which part of the lung (apex/base) is the best ventilated?
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Base
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Which part of the lung (apex/base) is the best perfused?
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Base
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The base of the lung has more ventilation or perfusion?
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Perfusion
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The base of the lung is a shunt or dead space?
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Shunt
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What is the volume of anatomic dead space? (mL/kg)
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2
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What are the two most important buffering systems in the body?
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HCO3 (50%), Hemoglobin (35%)
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A pH drop of 0.1 will increase K by how much?
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0.6 mEq/L
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What are the three ABG compensation rules?
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(1) 1 mmHg PaCO2 = 0.08 pH (2) 1 HCO3 = 1 PaCO2 (3) 10 HCO3 = 0.15 pH
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How do volatile anesthetics affect the Hb-O2 curve? |
Right-shift |
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What is the half-life of CO-Hb at room air?
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4 hours
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What is the half-life of CO-Hb at 100% O2?
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1 hour
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How do you speed up clearance of CO beyond 100% O2? |
Hyperbaric 3atm: half-life decreases to 15-30 minutes |
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At what duration and rate does propofol cause PIS? |
>48 hrs @ 88 mcg/kg/min |
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Anion gap formula? |
Na - (Cl + HCO3) [normal <12] |
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Organophosphates cause: miosis or mydriasis?
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Miosis (constriction)
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How does acidosis affect vessel tone?
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Vasodilation (think of sepsis)
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How does acidosis affect ICP?
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Increased ICP
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How does acidosis affect pulmonary vascular resistance?
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Increased pulmonary hypertension
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What is the key factor you can change to increase arterial saturation in one-lung ventilation?
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Increase MvO2
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What is the extubation criteria for vital capacity? |
> 15 mL/kg (2 x VT) |
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What is the extubation criteria for NIF?
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Less than -20 cm H2O
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What is the extubation criteria for PaCO2?
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< 50 mmHg
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What is the extubation criteria for A-a gradient? |
< 35 mmHg ? |
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What is the extubation criteria for dead space?
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< 0.6 Vd/Vt
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What is the extubation criteria for PaO2?
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> 60 mmHg on < 50% O2
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After what time period of a trauma should you be wary of using SCh?
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> 24 hours
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Spinal cord transection at C7: how does it affect autonomic hyper-reflexia? |
No effect; this is a chronic problem |
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Hypernatremia after head injury in old person: Cause?
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Diabetes insipidus (central decreased ADH release)
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What is the best treatment for hypotension in severe acidosis?
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Vasopressin
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How does TRALI manifest?
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Fever, increased A-a gradient, bilateral pulmonary infiltrates, leukoPENIA
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What would you expect the neutrophil count in TRALI to be?
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low (sequestration in lung)
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What is the vein just before the SVC where the SC and IJ meet?
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Brachiocephalic
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What is the ratio of compressions to breaths in a newborn?
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3:1 (90 compressions to 30 breaths per minute!)
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How does anthrax manifest on CXR?
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Widened mediastinum from large lymph nodes due to spores
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Atelectasis: shunt or dead space?
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Shunt
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Mainstem intubation: shunt or dead space?
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Shunt
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Hypovolemia: shunt or dead space?
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Dead space (decreased perfusion)
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Energy expenditure in sepsis + fever? (% compared to normal)
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140
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Energy expenditure in multiple fractures? (% compared to normal)
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120
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Energy expendite in burns? (% compared to normal)
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200%
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At what temperature(s) is energy expenditure the least in burns?
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33C (180%) < 21C (200%) < 25C (room air; 220%)
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Energy expenditure in post-op period? (% compared to normal) |
100% |
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High mixed venous oxygen saturation indicates what?
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Hypoperfusion to peripheral tissues
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High mixed venous oxygen saturation in a liver failure patient indicates what kind of circulatory failure?
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Hyperdynamic shock due to vasodilation
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Patient found to have normal anion gap metabolic acidosis with high Cl after surgery: what could have caused this? |
Normal saline fluid resuscitation |
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How does pneumothorax affect EtCO2? |
No effect (dead space remains the same, a new shunt is formed) |
