Ch. 2 Critical Care: Anesthesiology, Blood Gases, and Respiratory Care Flashcards
A 75 y/o thin cachectic woman undergoes a tracheostomy for failure to wean from the ventilator. One week later, she develops significant bleeding from the tracheostomy. Which of the following would be an appropriate initial step in the mgmt of this problem?
a. Remove tracheostomy and place pressure over the wound.
b. Deflate the balloon cuff on the tracheostomy.
c. Attempt to reintubate the patient with an endotracheal tube.
d. Upsize the tracheostomy.
e. Perform fiberoptic evaluation immediately.
c. Attempt to reintubate the patient with an endotracheal tube.
The patient has a sentinel bleed from a tracheoinnominate artery fistula, which carries a greater than 50% mortality rate. If the bleeding has ceased, then immediate fiberoptic exploration in the OR is indicated. If the bleeding is ongoing, several stopgap measures can be attempted while preparing for median sternotomy in the OR, including 1) reintubation of the pt with an endotracheal tube, 2) inflating the tracheostomy balloon to attempt compression of the innominate artery.
A 53 y/o woman has been intubated for several days after sustaining a R pulmonary contusion after a MVC as well as multiple rib fractures. Which of the following is a reasonable indication to attempt extubation?
a. Negative inspiratory force (NIF) of -15 cm H2O
b. PO2 of 60 mm Hg while breathing 30% inspired FiO2 with PEEP of 10 cm H2O.
c. Spontaneous RR of 35 bpm
d. Rapid shallow breathing index of 80
e. Minute ventilation of 18 L/min
d. Rapid shallow breathing index of 80
- Rapid shallow breathing index = ratio of RR to TV
- index between 60 and 105 predicts successful extubation
- NIF should be at least greater than -20 cm H2O
- Pt should be weened to PEEP of 5 cm before extubation
- Minute ventilation (RRxTV) should be less than 10 L/min
A 74 y/o woman with a hx of previous total abdominal hysterectomy presents with abdominal pain and distention for 3 days. She is noted on plain films to have dilated small-bowel and air-fluid levels. She is taken to the OR for SBO. Which of the following inhalational anesthetics should be avoided b/c of accumulation in air-filled cavities during general anesthesia?
a. Diethyl ether
b. Nitrous oxide
c. Halothane
d. Methoxyflurane
e. Trichloroethylene
b. NO
NO has a low solubility compared with other inhalation anesthetics; NO is more soluble in blood than nitrogen and is the only anesthetic gas less dense than air. As a result, NO may cause progressive distension of air-filled spaces during prolonged anesthesia.
Since NO diffuses into gas-filled compartments faster than nitrogen can diffuse out, its use can lead to worsened distention, which may be undesirable (e.g., in an operation for intestinal obstruction)
A 61 y/o alcoholic man presents with severe epigastric pain radiating to his back. His amylase and lipase are elevated, and he is diagnosed with acute pancreatitis. Over the first 48 hrs, he is determined to have 6 Ranson’s criteria, including a PaO2 < 60 mm Hg. His CXR reveals bilateral pulmonary infiltrates and his wedge pressure is low. Which of the following criteria must be met to make a dx of ARDS?
a. Hypoxemia defined as PaO2/FiO2 ratio < 200
b. Hypoxemia defined as PaO2 < 60 mm Hg
c. PCWP > 18 mm Hg
d. Lack of improvement in oxygenation with administration of furosemide
a. Hypoxemia defined as PaO2/FiO2 ratio < 200
ARDS dx can be made based on:
- B/l pulmonary infiltrates on CXR
- PaO2/FiO2 < 200
- PCWP < 18 mm Hg (low filling pressures exclude dx of pulmonary edema)
3 major physiologic alterations include:
- Hypoxemia usually unresponsive to elevations of inspired O2 concentration
- Decreased pulmonary compliance, as the lungs become progressively stiffer and harder to ventilate
- Decreased FRC
Progressive alveolar collapse occurs owing to leakage of protein-rich fluid into the interstitium and the alveolar spaces with subsequent radiologic picture of diffuse fluffy infiltrates b/l.
Ventilatory abnormalities develop that result in shunt formation, decreased resting lung volume, and increased dead-space ventilation.
A 64 y/o man with hx of severe emphysema is admitted for hematemesis. The bleeding ceases soon after admission, but the patient becomes confused and agitated. ABG are as follows:
- pH 7.23
- PO2 42 mm Hg
- PCO2 75 mm Hg
Which of the following is the best initial therapy for this pt?
a. Correct hypoxemia with high-flow nasal O2
b. Correct acidosis with sodium bicarbonate
c. Administer 10 mg IV dexamethasone
d. Administer 2 mg IV Ativan
e. Intubate the pt
e. Intubate the pt
Pt is suffering from respiratory acidosis, caused by accumulation of CO2, and hypoxemia. Both disturbances can be resolved with endotracheal intubation and ventilatory support.
Benzodiazepines such as Ativan in this pt will cause stupor and worsen his hypoxemia and respiratory acidosis.
A 62 y/o woman with a hx of CAD presents with pancreatic head tumor and undergoes a pancreaticoduodenectomy. Postop, she develops a leak from the pancreaticojejunostomy anastomosis and becomes septic. A Swan-Ganz catheter is placed, which demonstrates an increased CO and decreased systemic vascular resistance. She also develops acute renal failure and oliguria. Which of the following is an indication to start dopamine?
a. To increase splanchnic flow
b. To increase coronary flow
c. To decrease HR
d. To lower peripheral vascular resistance
e. To inhibit catecholamine release
b. To increase coronary flow
At all doses, the diastolic BP can be expected to rise; coronary perfusion will therefore increase.
- In low doses, dopamine affects primarily dopaminergic receptors –> vasodilation of renal and mesenteric vasculature and mild vasoconstriction of peripheral bed, which redirect blood flow to kidneys and bowel
- In medium doses, B1 activity predominates –> inotropic effect on myocardium –> increased CO and BP
- In high doses, alpha-receptor stimulation –> peripheral vasoconstriction –> shift of blood from extremities to organs, decreased kidney fxn, and HTN
A 29 y/o woman on OCP presents with abdominal pain. A CT scan of the abdomen demonstrates a large hematoma of the R liver with suggestion of an underlying liver lesion. Her Hgb = 6, and she is transfused 2 units pRBC and 2 units FFP. Two hours after starting transfusion, she develops respiratory distress and requires intubation. She is not volume overloaded clinically, but her CXR shows bilateral pulmonary infiltrates. Which of the following is the mgmt strategy of choice?
a. Continue the transfusion and administer an antihistamine
b. Stop the transfusion and administer a diuretic
c. Stop the transfusion and continue respiratory care
d. Stop the transfusion and send a Coombs test
c. Stop the transfusion and continue respiratory care
Patient has TRALI (transfusion-related acute lung injury) which manifests as respiratory distress, hypoxemia, and b/l pulmonary infiltrates not due to volume overload. Tx = supportive
a. Continue the transfusion and administer an antihistamine –> for allergic rxn
b. Stop the transfusion and administer a diuretic –> for TACO (transfusion associated circulation overload) in pts with CHF who receive large transfusion
d. Stop the transfusion and send a Coombs test –> hemolytic rxn… ID responsible antigen to prevent future rxns
A 59 y/o man with hx MI 2 years ago undergoes an uneventful aortobifemoral bypass graft for aortoiliac occlusive disease. Six hours later, he develops ST segment depression, and ECG shows anterolateral ischemia. His hemodynamic parameters are as follows:
- systemic BP: 70/40
- Pulse: 100
- CVP: 18 mm Hg
- PCWP: 25 mm Hg
- CO: 1.5 L/min
- SVR: 1000
Which of the following is the single best pharmacologic intervention for this pt?
a. Sublingual NG
b. IV NG
c. Short-acting beta blocker
d. Sodium nitroprusside
e. Dobutamine
e. Dobutamine
Pt has developed pump failure b/c of combination of preexisting coronary artery occlusive disease and high preload following a fluid challenge; afterload remains moderately high as well because of systemic vasoconstriction in the presence of cardiogenic shock. Poor myocardial performance is reflected in the low CO and high PCWP. Therapy must be directed at increasing CO without creating too high a myocardial O2 demand on the already failing heart.
Administration of NG could be expected to reduce both preload and afterload, but, if given without an inotrope, it would create unacceptable hypotension. Same goes for Nitroprusside.
Dobutamine = inotropic agent of choice in cardiogenic shock.
B1 adrenergic agonist –> improves cardiac performance in pump failure both by 1) positive inotropy and 2) peripheral vasodilation
With minimal chronotropic effect, dobutamine only marginally increases myocardial O2 demand
A 73 y/o woman w/ a long hx of heavy smoking undergoes femoral artery-popliteal artery bypass for rest pain in her left leg. Because of serious underlying respiratory insufficiency, she continues to require ventilatory support for 4 days after her operation. As soon as her endotracheal tube is removed, she begins complaining of vague upper abdominal pain. She has daily fever spikes 102.2 and a leukocyte count of 18,000/mL.
An upper U/S reveals a dilated gallbladder, but no stones are seen. A presumptive dx of acalculous cholecystitis is made. Which of the following is the next best step in her tx?
a. NG suction and broad-spectrum abx
b. Immediate chole
c. Percutaneous drainage of gallbladder
d. ERCP to visualize and drain CBD
c. Percutaneous drainage of gallbladder
The development of acute postop cholecystitis is an increasingly recognized complication of the severe illness that precipitate admissions to the ICU.
Percutaneous drainage of the gallbladder is usually curative of acalculous cholecystitis and affords stabilizing palliation.
ERCP is not indicated in the absence of ductal obstruction.
A 43 y/o trauma pt develops ARDS and has difficulty oxygenating despite increased concentrations of inspired O2. After PEEP is increased, the patient’s oxygenation improves. What is the mechanism by which this occurs?
a. Decreasing dead-space ventilation
b. Decreasing minute ventilation requirement
c. Increasing tidal volume
d. Increasing FRC
e. Redistribution of lung water from the interstitial to the alveolar space
d. Increasing FRC
PEEP improves oxygenation by increasing FRC by keeping alveoli open at the end of expiration
A 22 y/o man sustains severe blunt trauma to the back. He notes that he cannot move his lower extremities. He is hypotensive and bradycardic. Which of the following is the best initial mgmt of the pt?
a. Administration of phenylephrine
b. Administration of dopamine
c. Administration of epi
d. IV fluid bolus
e. Placement of transcutaneous pacer
d. IV fluid bolus
Pt is in neurogenic shock as a result of spinal cord injury
Loss of sympathetic tone peripherally + bradycardia owing to loss of reflexive increase in HR in response to hypotension
Initial tx = fluid resuscitation –> initiation of vasoconstrictors (dopamine, phenylephrine)
A 58 y/o woman with multiple comorbidities and previous cardiac surgery is in a high-speed MVC. She is intubated for airway protection. Because of hemodynamic instability, a CVP catheter is placed in the R subclavian vein. While the surgeon is securing the catheter, the cap becomes displaced and air enters the catheter. Suddenly, the pt becomes tachycardic and hypotensive. What is the next best manuever?
a. Decompress R chest with needle in 2nd intercostal space
b. Placement of R chest tube
c. Withdrawal of central venous catheter several centimeters
d. Placement of pt in L lateral decubitus Trendelenburg position
d. Placement of pt in L lateral decubitus Trendelenburg position
Scenario: air embolism
Initial maneuvers: place pt in L lateral decubitus Trendelenburg (head-down) and aspirate central venous catheter
- a. Decompress R chest with needle in 2nd intercostal space –> tension pneumo
- b. Placement of R chest tube –> hemothorax
- Withdrawal of central venous catheter several centimeters –> arrhythmias occur during line insertion
A 30 y/o man is scheduled for laparoscopic chole for biliary colic. He reports a family hx of prolonged paralysis during general anesthesia. Which of the following meds should be avoided during his procedure?
a. Succinylcholine
b. Vecuronium
c. Pancuronium
d. Halothane
e. Etomidate
a. Succinylcholine
Fam hx is suggestive of pseudocholinesterase deficiency which prolongs the effects of succinylcholine, a depolarizing neuromuscular blocking agent, as well as mivacurium, a non-depolarizing agent.
- Etomidate is used for rapid sequence induction and is not affected by pseudocholinesterase deficiency;
- does block steroid synthesis and has been associated with acute adrenal insufficiency
An 18 y/o woman develops urticaria and wheezing after an injection of IV contrast for abdominal CT scan. Her bp is 120/60 mm Hg, HR = 155 bpm, RR = 30. Which of the following is the most appropriate immediate therapy?
a. Intubation
b. Epi
c. Beta blockers
d. Iodine
e. Fluid challenge
b. Epi
Epi = initial tx for laryngeal obstruction and bronchospasm… then histamine antagonists (H1 and H2 blockers), aminophylline, and hydrocortisone
Intubation reserved for unconscious pts
A 74 y/o man w/ diabetes, renal insufficiency, and coronary artery disease presents in septic shock from emphysematous cholecystitis. His oxygen saturation is 100% on 6 L nasal cannula and his Hgb = 7.2 mg/dL. His mixed venous oxygen saturation is 58%. Which of the following treatment options will improve his oxygen delivery the most?
a. Increase his inspired oxygen concentration
b. Transfer him to a hyperbaric chamber
c. Administer ferrous sulfate
d. Administer an erythropoietic agent
e. Transfuse two units of pRBCs
e. Transfuse 2 units of pRBCs
Mixed venous oxygen saturation reflects difference between oxygen delivered to tissues and oxygen taken up by tissues.
Correction of patient’s anemia by transfusion of blood is the treatment of choice.
