D) lytic degeneration, edema and necrosis of skeletal muscle
Intravenous lidocaine decreases cerebral blood flow unless seizure activity develops. Lidocaine decreases the refractory period of cardiac muscle and decreases platelet aggregation while enhancing fibrinolysis. Local anesthetics have been shown to cause lytic degeneration and necrosis of muscle fibers when directly injected into the muscle (trigger point injections).
Correct statements concerning the use of antidepressants in pain management include:
D) analgesic effects appear to be secondary to the blockade of serotonin and norepinephrine reuptake
Antidepressants demonstrate an analgesic effect at doses lower that those needed for antidepressant effect. Both actions appear secondary to the block of the reuptake of serotonin and norepinephrine. Older tricyclic antidepressants seem more effective analgesics than the newer SSRIs. Antidepressants are most useful in patients with neuropathic pain.
The dibucaine number:
C) reflects inhibition of pseudocholinesterase by dibucaine
Dibucaine, a local anesthetic, inhibits normal pseudocholinesterase. Homozygous patients with abnormal pseudocholinesterase characteristically have a dibucaine number of about 20%, heterozygous patients have numbers of 40 - 60% and normal patients usually have a dibucaine number of 80%. The dibucaine number is proportional to pseudocholinesterase function, but is independent of the amount of the enzyme.
The body mass index (BMI) associated with extreme obesity is:
B) > 40
Overweight and obesity are classified using the BMI. Overweight is defined as a BMI > 24, obesity as a BMI > 30 and extreme obesity as a BMI > 40. BMI is calculated with the following formula:
BMI = Weight (kg) / Height (meters)2
Release of aldosterone by the adrenal cortex is stimulated by: (select 3)
B) angiotensin II
d) pituitary ACTH
e) congestive heart failure
Aldosterone release is stimulated by the renin-angiotensin system, but specifically by angiotensin II. Other causes of aldosterone release include hyperkalemia, ACTH release, hypovolemia, hypotension, CHF and the stress response.
Renal blood flow: (Select 2)
D) accounts for 20 - 25% of the cardiac output
d) can be directed away from cortical nephrons by sympathetic stimulation
The kidneys are the only organ for which oxygen consumption is determined by blood flow; the reverse is true in other organs. The kidneys receive 20 - 25% of the cardiac output with only 10 - 15% going to the juxtamedullary nephrons and 80% going to cortical nephrons. However, blood flow can be redirected to juxtamedullary nephrons by increased levels of catecholamines and angiotensin II. Autoregulation of RBF occurs between mean arterial pressures of 80 - 180 mmHg.
A 36-year-old female is scheduled for an elective cholecystectomy. Her past medical history is significant for depression treated with phenelzine (Nardil). Her anesthetic plan should include: (Select 2)
D) the avoidance of meperidine
b) the avoidance of indirect acting vasopressors
Phenelzine is a monamine oxidase (MAO) inhibitor. The practice of discontinuing MAO inhibitors prior to surgery is no longer recommended. The use of meperidine in patients receiving MAO inhibitors has been associated with hypertensive crisis and should be avoided. Additionally, indirect acting vasopressors have also been associated with hypertensive crisis and direct acting vasopressors should be used to treat hypotension.
Neuroleptic malignant syndrome:
D) can be precipitated with the use of metoclopramide
Neuroleptic malignant syndrome is a rare complication of antipsychotic therapy. Meperidine and metoclopramide can also precipitate the disorder which appears to be secondary to dopamine blockade in the basal ganglia. The disease has many characteristics in common with MH including increased temperature, metabolic derangement and hyperthermia. The mortality is 20 - 30%. Treatment with dantrolene and dopamine agonist, bromocripitine, appears effective.
The most common complication of thoracic paravertebral nerve block is:
Pneumothorax is the most common complication of paravertebral block and a chest radiograph is needed upon completion of the block. Other complications include subarachnoid injection, epidural injection, intravascular injection, and hypotension.
The number of dichotomous divisions of the tracheobronchial tree from the trachea to the alveolar sacs is approximately:
Dichotomous division, each branch dividing into two smaller branches, of the tracheobronchial tree is estimated to involve 20 - 25 divisions.
The largest fraction of carbon dioxide in the blood is in the form of:
Nearly 90% of carbon dioxide in the blood is in the form of bicarbonate.
A 42-year-old man is undergoing a thoracoscopy. During the procedure an 8-minute period of apneic oxygenation is required. If the patient's PaCO2 is 40 mmHg, the expected PaCO2 at the end of the apneic period would be: (Enter numerical answer on the line below.)
67 to 74 mmHg
The apneic oxygenation technique affords adequate oxygen delivery, but progressive respiratory acidosis limits the use of this technique to 10 - 20 minutes in most patients. Arterial PaCO2 rises 6 mmHg in the first minute followed by a rise of 3 - 4 mmHg during each subsequent minute. In this patient this will produce a 27 - 34 mmHg increase, resulting in a PaCO2 of 67 to 74 mmHg.
Stimulation of the parasympathetic nervous system results in:
C) increased insulin secretion
Insulin secretion is increased by stimulation of the parasympathetic nervous system through the vagus nerves.
The formation clinically significant amounts of carbon monoxide has been associated with:
a) the use of a non-rebreathing circuit b) the use of fresh carbon dioxide absorber
c) the use of desflurane
d) expiratory valve incompetence
c) the use of desflurane
The formation of CO depends on the use of a volatile agent containing a difluoromethoxy moiety (desflurane, isoflurane, enflurane). This moiety can react with desiccated base (baralime or sodalime) to form CO. Fresh absorber has sufficient water to prevent the reaction. Clinically, CO intoxication occurs after a weekend when the flow of dry oxygen in the machine has desiccated the absorber and desflurane is being used.
Positive end expiratory pressure (PEEP):
D) decreases intrapulmonary shunting
The major effect of PEEP is to increase FRC and tidal ventilation above the closing capacity. This results in a decrease in intrapulmonary shunting. Neither PEEP or CPAP decrease extravascular lung water. By increasing intrathoracic pressure, PEEP decreases venous return to the heart.
The essential component of cardioplegia solutions is:
High concentrations of potassium (10 - 40 mEq/L) are used in cardioplegia solutions. These solutions result in an increase in extracellular potassium and reduce transmembrane potential. This progressively interferes with the normal sodium currents of depolarization and eventually the sodium channels are completely inactivated.
Forms of mechanical ventilation that produce tidal volumes at or below anatomic dead space include: (Select 2)
A) high-frequency oscillation
e) high-frequency positive-pressure ventilation
High-frequency oscillation (HFO) creates a to-and-fro gas movement in the airway at rates of 180 - 3000 times/min. High frequency positive-pressure ventilation is delivered at a rate of 60 - 120 breaths/min. Tidal volume is at or below anatomic dead space. High-frequency ventilation techniques may be useful in cases of bronchopleural and tracheoesophageal fistulas.
In the absence of hypoxia or severe anemia, the best determinant of the adequacy of cardiac output is:
A) mixed venous oxygen tension
Both cardiac output and cardiac index have a wide range and may not reflect the adequacy of cardiac output against metabolic requirements. During periods of increased oxygen consumption, mixed venous oxygen tension is the best indicator of the adequacy of cardiac output.
The most significant preoperative cardiac risk factor is:
D) evidence of congestive heart failure
The two most important preoperative cardiac risk factors are evidence of CHF and unstable coronary syndrome.
The incidence of chronic active hepatitis following infection with the hepatitis C virus is approximately:
The incidence of chronic active hepatitis following hepatitis C infection is at least 50%; 3 - 10% following hepatitis B infection
Pulmonary changes associated with Duchenne's muscular dystrophy include:
A) a restrictive ventilatory defect
The combination of marked kyphoscoliosis and degeneration of the respiratory muscles produces a severe restrictive ventilatory defect in patients with Duchenne's muscular dystrophy. Pulmonary hypertension is also commonly seen.
A 46-year-old male is scheduled for an emergent laparotomy for small bowel obstruction. His history is complicated by the acute onset of hepatitis B four days earlier and he presents with significant scleral jaundice. The perioperative mortality in this patient is approximately:
Patients with acute hepatitis should have elective surgery postponed until the acute hepatitis has resolved. Studies indicate increased perioperative morbidity (12%) and mortality (10% with laparotomy) during acute hepatitis.
An increase in intraocular pressure has been associated with: (select 3)
G) succinylcholine administration
Succinylcholine increases intraocular pressure by 5 - 10 mmHg for 5 - 10 minutes after administration. This increase is primarily the result of prolonged contracture of the extraocular muscles from the depolarizing effects of succinylcholine. Nitrous oxide, volatile anesthetic agents and opioids have been associated with a reduction in intraocular pressure. Hypoxemia, hypercarbia, hypertension, hypervolemia, laryngoscopy and intubation have all been shown to increase IOP.
Current anesthesia apparatus checkout recommendations suggest which of the following prior to every case?
A) Check the carbon dioxide absorber
Verification of the adequacy of the carbon dioxide absorber is suggested prior to every case. If the same anesthesia machine is being used by the same provider, E-cylinder pressure checks, machine low-pressure leak testing and calibration of the oxygen sensor need not be repeated after an initial check.
According to the Modified Glasgow Coma Scale, a moderate head injury is associated with a score of:
D) 9 - 12
According to the Modified Glasgow Coma scale, mild head injury is associated with a score of 13 - 15, moderate head injury is associated with a score of 9 - 12, and severe head injury is associated with a score of less than 8.
The addition of bicarbonate to a local anesthetic solution:
B) increases the concentration of the nonionic form of the local anesthetic
The onset of neural blockade depends on the penetration of the nerve cell membrane by the nonionic form of the anesthetic. Increasing the pH of the anesthetic solution increases the concentration of the nonionic form and thereby hastens the onset of the block. Bicarbonate is usually not added to bupivacaine, since it can cause precipitation if the pH is raised above 6.8.
Factors increasing the affinity of hemoglobin for oxygen include: (Select 2)
a) increased carbon dioxide levels
b) increased 2,3-DPG levels
c) increased pH
d) the presence of fetal hemoglobin
e) increased body temperature
f) the presence of hemoglobin-S
c) increased pH
d) presence of fetal hemoglobin
Factors that increase the affinity of hemoglobin for oxygen would cause a leftward shift of the hemoglobin dissociation curve and a decrease in the P50. These factors include alkalosis, decreased CO2 levels, and decreased 2,3-DPG levels. Hemoglobin-S, found in patients with sickle cell disease, has a decreased affinity for oxygen. Fetal hemoglobin, however, has an increased affinity for oxygen to help in oxygen transfer from the mother to the fetus
Laminar flow in the airway occurs in the: (Select 2)
A) terminal bronchiole
e) respiratory bronchiole
Flow in the larger airways is mostly turbulent. Laminar flow normally occurs only distal to small bronchioles (< 1mm). The Reynolds number is used to predict the type of airway flow; a low Reynolds number (< 1000) is associated with laminar flow, whereas a high value (> 1500) is associated with turbulent flow.
Sickle hemoglobin: (Select 2)
C) readily polymerizes and precipitates in the red cell
f) has decreased solubility as compared to hemoglobin A
Sickle hemoglobin (HbS) has a lower affinity for oxygen and an elevated P50 (31 mmHg) as compared to hemoglobin A (27 mmHg). HbS also has decreased solubility and readily polymerizes and precipitates in the red cell producing the sickled appearance of the cell. HbS results from the substitution of valine for glutamic acid on the β-chain.
Nerves blocked with a fascia iliaca block include the:
C) femoral nerve
The fascia iliaca block utilizes a deposition of local anesthetic in the fascia iliaca compartment to block the femoral, lateral femoral cutaneous, obturator and genitofemoral nerves.
Average blood loss during a vaginal delivery is:
C) 400 - 500 ml
At term, blood volume has increased by 1000 - 1500 ml in most women allowing them to easily tolerate the blood loss associated with delivery. Average blood loss during vaginal delivery is 400 - 500 ml, compared with 800 - 1000 ml for cesarean section.
Examples of Type IV hypersensitivity reactions include:
D) contact dermatitis
Type IV hypersensitivity reactions are delayed and cell-mediated. Examples of Type IV reactions include contact dermatitis, tuberculin-type hypersensitivity and chronic hypersensitivity pneumonitis.
The maximum recommended occupational whole-body exposure to radiation is:
A) 5 rem/year
The intraoperative use of imaging equipment exposes anesthesia providers to ionizing radiation. The maximum recommended whole-body exposure to radiation is 5 rem/year.
Characteristics of omphalocele include: (Select 2)
C) association with Trisomy 21
c) results from the failure of midgut migration into the abdomen
Gastroschisis and omphalocele are characterized by defects in the abdominal wall that allow herniation of the viscera. Omphaoceles occur at the base of the umbilicus, have a hernia sac and are commonly associated with other anomalies. In contrast, gastroschisis is usually lateral to the umbilicus, lacks a hernia sac and is usually an isolated finding. Nitrous oxide is best avoided during repair as it may result in bowel distention making closure more difficult.
Absolute contraindications to the use of epidural anesthesia in the parturient include: (Select 2)
C) inability of the patient to cooperate
d) patient refusal
Absolute contraindications to epidural anesthesia/analgesia in the parturient include infection over the injection site, coagulopathy, thrombocytopenia, marked hypovolemia, true local anesthetic allergy, patient refusal and inability of the patient to cooperate. Preexisting neurological disease and back disorders are relative contraindications. Patients with aortic regurgitation usually benefit from the reduction in afterload seen after neuraxial anesthesia.
Basal metabolic oxygen consumption in a 20 kg patient is approximately:
B) 95 ml/min
Basal metabolic oxygen consumption can be estimated using the following formula:
VO2 = 10Kg3/4
Bone marrow depression and peripheral neuropathy have been associated with prolonged exposure to anesthetic concentrations of:
A) Nitrous oxide
By irreversibly oxidizing the cobalt atom in vitamin B12, nitrous oxide inhibits vitamin B12 dependent enzymes. These enzymes include methionine synthetase and thymidylate synthetase. As a result of these enzyme inhibitions, prolonged exposure to nitrous oxide has been associated with bone marrow depression, megaloblastic anemia, peripheral neuropathy and teratogenicity.
An increase in the plasma concentration and a prolongation of the elimination half-life of etomidate is seen with the concomitant administration of:
Fentanyl has been shown to increase the plasma level of etomidate as well as prolong the elimination half-life of the drug
Disodium edetate or sodium metabisulfite is added to formulations of propofol to:
A) inhibit bacterial growth
Current formulations of propofol contain 0.005% disodium edetate or 0.025% sodium metabisulfite to help retard the rate of microorganism growth.
During emergent transtracheal jet ventilation using a 14 gauge catheter, generation of sufficient gas flow requires a driving pressure of:
D) 50 psi
After proper location of the catheter is confirmed by aspiration air, jet ventilation may be achieved with intermittent pulses of oxygen at 50 psi.
Sensory innervation of the trachea and larynx below the vocal cords is supplied by the:
A) recurrent laryngeal nerve
The vagus nerve provides sensation to the airway below the epiglottis. The superior laryngeal branch of the vagus divides into an external (motor) and internal (sensory) laryngeal nerve that provide sensory supply to the larynx between the epiglottis and the vocal cords. Another branch of the vagus, the recurrent laryngeal nerve, innervates the larynx below the vocal cords and trachea.
A 24-year-old female is scheduled for resection of a cerebral aneurysm. She has no other significant past medical history. Acceptable levels of hypotension would include a mean arterial pressure of:
B) 50 - 60 mmHg
Healthy young individuals tolerate mean arterial pressures as low as 50 - 60 mmHg without complications. Chronically hypertensive patients have altered autoregulation of cerebral blood flow and may tolerate a mean arterial pressure of no more than 20 - 30% below baseline.
Correct statements concerning the use of benzodiazepines in the elderly include:
A) volume of distribution is increased
Aging increases the volume of distribution for all benzodiazepines, effectively prolonging their elimination half-lives. Enhanced pharmacodynamic sensitivity is also observed. The elimination half-lives of both diazepam and midazolam are increased.
Concerning preoperative informed consent:
C) charges of assault and battery are possible if it is not obtained
Any procedure performed without the patient's consent can constitute assault and battery. Oral consent may be sufficient, but written consent is advisable for medicolegal purposes. It is generally accepted that not all risks need to be detailed, but risks that are realistic and have resulted in complications in similar patients should be disclosed.
The National Institute for Occupational Safety (NIOSH) recommends limiting the operating room concentration of nitrous oxide to:
A) 25 ppm
NIOSH recommends limiting the room concentration of nitrous oxide to 25 ppm and halogenated agents to 2 ppm (0.5 ppm if nitrous oxide is also being used).
The highest incidence of muscle pain following the use of succinylcholine is seen in:
Myalgia following the use of succinylcholine is most commonly seen in females and outpatients. Pregnancy and extremes of age seem to be protective.
The cardiovascular effects of pancuronium are caused by: (Select 3)
E) vagal blockade
c) ganglionic stimulation
d) decreased catecholamine reuptake
The cardiovascular effects of pancuronium are caused by the combination of vagal blockade and sympathetic stimulation. The latter is due to a combination of ganglionic stimulation, catecholamine release and decreased catecholamine reuptake.
Anesthetic implications of multiple sclerosis include:
A) exacerbation induced by spinal anesthesia
Spinal anesthesia has been reported to cause exacerbation of the disease. Epidural and other regional techniques appear to have no adverse effect, especially in obstetrics. Demyelinated nerve fibers are extremely sensitive to hyperthermia, but conduction is usually improved by mild hypothermia.
Local anesthetics with the potential to form methemoglobin include: (Select 3)
C) EMLA topical anesthetic cream
EMLA cream contains both lidocaine and prilocaine. The metabolites of prilocaine can convert hemoglobin to methemoglobin. Benzocaine can also cause methemoglobinemia. Case studies have also associated methemoglobinemia with tetracaine and lidocaine use.
During hip replacement surgery, cardiopulmonary changes associated with the application of acrylic bone cement include: (Select 3)
a) hypotension secondary to cement monomer absorption
b) hypoxemia secondary to air embolization
c) hypoxemia secondary to fat embolization
e) decreased pulmonary artery pressure
f) increased end-tidal carbon dioxide
a) hypotension secondary to cement monomer absorption
b) hypoxemia secondary to air embolization
c) hypoxemia secondary to fat embolization
During hip replacement surgery, hypotension associated with the use of acrylic bone cement has been attributed to absorption of methyl methacrylate monomer, embolization of air and bone marrow, lysis of red cells and marrow and conversion of methyl methacrylate to methacrylic acid. Hypoxemia is common. Embolic events cause an increase in dead space with a reduction in ETCO2 with an increase in PaCO2. (Nagelhout pg. 977, Barash pg. 1389)