C) decreased renal blood flow secondary to increased renal vascular resistance
Nitrous oxide appears to decrease renal blood flow by increasing renal vascular resistance. This results in decreased glomerular filtration and decreased urine output. (M&M pg. 164)
The potency of local anesthetics increases as the:
C) lipid solubility increases
Local anesthetic potency correlates directly with lipid solubility. In general, lipid solubility increases with an increase in the total number of carbon atoms in the molecule and by adding a halogen to the aromatic ring.
A decrease in cerebral blood flow is seen after the administration of:
The inhaled anesthetic agents and ketamine all increase cerebral blood flow (CBF). Benzodiazepines, etomidate, propofol and barbiturates all decrease CBF.
The age group with the highest minimum alveolar concentration (MAC) of desflurane is:
A) 2 - 3 months
The two-to-three-months-of-age group represents the highest MAC requirement. MAC subsequently decreases with advancing age.
The loss of ventricular filling as a result of acute atrial fibrillation is approximately:
Passive flow accounts for about 75% of ventricular filling. The remaining 25% occurs as a result of atrial contraction, which is lost during atrial fibrillation.
During surgical repair of a detached retina, 1 mL of sulfur hexafluoride is injected into the posterior chamber. If the patient is receiving 4% desflurane and a 2:1 ratio of N2O and O2, the bubble will:
A) triple in volume
A sulfur hexafluoride gas bubble is sometimes used to support the retina after detachment. Diffusion of nitrous oxide into the bubble will cause expansion as nitrous oxide equilibrates with the gas bubble. A sixty-seven percent nitrous oxide concentration will cause the bubble to triple in size in about 30 minutes and may double the intraocular pressure (IOP). In addition, when nitrous oxide is discontinued, the bubble will return to normal size, causing a fall in IOP and possible extension of the retinal tear. For these reasons, it is recommended that nitrous oxide be discontinued at least 15 minutes prior to the injection of a posterior chamber bubble.
Topically applied ophthalmic medications are absorbed:
C) more quickly than subcutaneous administration
Topically applied ophthalmic medications are absorbed at a rate intermediate between intravenous and subcutaneous injection. Children and the elderly are at particular risk for the toxic effects of topically applied medications.
During pregnancy, the minimum alveolar concentration (MAC):
B) decreases throughout the pregnancy
The MAC progressively decreases during pregnancy, at term by as much as 40%. MAC returns to normal by the third day after delivery.
Correct location of the catheter tip of a central venous line is in the:
D) superior vena cava
The CVP catheter tip should not be allowed to migrate into the heart chamber to avoid arrhythmias and perforation.
Physiologic effects of electroconvulsive therapy (ECT) include an:
C) initial parasympathetic discharge followed by a sustained sympathetic response
An initial parasympathetic discharge followed by a sustained sympathetic response is immediately seen after the induction of a seizure. Marked bradycardia with increased secretions can occur, which is then followed by hypertension and tachycardia. Patients scheduled for ECT are routinely given anticholinergic medication preoperatively.
The postretrobulbar block apnea syndrome:
C) is associated with unconsciousness
The postretrobulbar block apnea syndrome is probably due to injection of local anesthetic into the optic nerve sheath, with spread into the CSF. The CNS is exposed to high concentrations of local anesthetic leading to apprehension and unconsciousness. Apnea occurs within 20 minutes and resolves within an hour. Treatment is supportive.
A 76-year-old man is scheduled for a hemicolectomy. His past medical history is significant for third degree heart block treated with a permanent pacemaker. Problems with electrocautery use in this patient can be minimized by:
C) the use of a bipolar cautery
Electrical interference from the electrocautery can be interpreted by the pacemaker as myocardial activity and suppress pacemaker activity. These problems can be minimized by limiting use to short bursts, placing the grounding pad as far from the pacemaker as possible and using a bipolar cautery.
The arteria radicularis magna, or artery of Adamkiewicz, most commonly arises from:
B) T8 - L2
A major complication of thoracic aortic surgery is paraplegia, occurring in up to 20% of elective cases, and is secondary to spinal cord ischemia. The arteria radicularis magna supplies blood to the anterior spinal artery. The arteria radicularis magna has a variable origin from aorta, arising between T5 - T8 in 15%, between T9 - T12 in 60% and between L1 - L2 in 25% of individuals.
The most severe transfusion reactions are due to:
B) ABO incompatibility
The most severe transfusion reactions are due to ABO incompatibility. Naturally acquired antibodies can react against the transfused antigens, activate complement and result in intravascular hemolysis.
Intracranial hypertension is defined as a sustained increase in intracranial pressure (ICP) above:
B) 15 mmHg
Intracranial hypertension is defined as a sustained increase in intracranial pressure (ICP) above 15 mmHg. Uncompensated increases in tissue or fluid within the rigid intracranial vault produce thesustained pressure elevations.
The rapid shallow breathing index (RSBI) is useful in predicting successful weaning from mechanical ventilation. Prior to extubation this index should be:
D) less than 100
RSBI is frequently used to help predict who can be successfully weaned from mechanical ventilation. With the patient breathing spontaneously, the ventilatory rate is divided by the tidal volume (liters). Successful extubation can be predicted by an RSBI of less than 100.
The perception of an ordinarily non-noxious stimulus as pain is referred to as:
Allodynia is the perception of non-noxious stimuli as pain. Dysesthesia is an unpleasant sensation without a stimulus. Hyperesthesia is an increased response to a mild stimulus. Anesthesia dolorosa is pain in an area that lacks sensation.
Cholinesterase inhibitors that freely cross the blood-brain barrier include:
Physostigmine is a teritary amine and has a carbamate group, but no quaternary ammonium. Therefore, it is lipid soluble and is the only clinically available cholinesterase inhibitor that freely passes the blood-brain barrier.
Ninety percent of congenital diaphragmatic hernias occur:
D) through the left posterolateral foramen
Left-sided herniation through the posterolateral foramen of Bochdalek accounts for 90% of diaphragmatic hernias. Hypoxia, scaphoid abdomen and evidence of bowel in the thorax are the hallmarks of diaphragmatic herniation. Peak airway pressures should not exceed 30 cm H2O to minimize the risk of pneumothorax during surgical correction.
During fetal monitoring, Type III decelerations are thought to be related to:
B) umbilical cord compression
Type III, or variable, decelerations are the most common type of decelerations. They are thought to be related to umbilical cord compression and intermittent decreases in umbilical blood flow.
Anesthetic complications associated with hypothyroidism include:
C) difficult intubation
Potential problems of hypothyroidism include hypoglycemia, anemia, hyponatremia and difficulty during intubation because of a large tongue. Hypothermia secondary to a low metabolic rate is a common postoperative complication. (M&M, pg 809)
Airway obstruction caused by the tongue falling posteriorly against the wall of the pharynx is secondary to relaxation of the:
A) genioglossus muscle
The genioglossus muscle allows the tongue to be protruded and kept away from the posterior pharynx. It is innervated by the hypoglossal nerve. The palatoglossus muscle elevates the tongue and depresses the soft palate. The styloglossus muscle elevates and retracts the tongue. The superior longitudinal muscle of the tongue is an intrinsic muscle of the tongue that elevates the tip.
Reactants that are regenerated during the absorption of carbon dioxide by soda lime include:
A) sodium hydroxide
Both water and sodium hydroxide are initially required during the absorption of carbon dioxide by soda lime, but then are regenerated.
The effects of barbiturates on ischemic areas of the brain include:
A) redirection of blood flow to the ischemic areas
Barbiturates cause cerebral vasoconstriction in normal areas. These agents tend to redistribute blood flow to ischemic areas in what is sometimes referred to as a reverse steal phenomenon or Robin Hood effect. Ischemic areas remain maximally dilated and unaffected by the barbiturate. (Nagelhout pg. 125, Barash pg. 451)
In patients receiving vecuronium, the greatest augmentation of neuromuscular blockade is seen with the use of:
Volatile agents decrease the nondepolarizer dosage requirements. The degree of the augmentation of blockade depends on the inhalational agent, with desflurane > sevoflurane > isoflurane > nitrous oxide. (Barash pg. 436, M&M pg. 218)
Portal hypertension is defined as sustained portal vein pressure greater than: checked
A) 10 mmHg
Portal hypertension is defined as a sustained portal vein pressure of 10 mmHg or greater. This leads to the formation of portal-systemic collateral venous channels.
In patients with a history of hypertrophic cardiomyopathy, intraoperative management should include:
A) maintenance of adequate preload
In patients with outflow obstruction, myocardial depression and maintenance of preload and afterload are desireable. (Nagelhout pg. 501)
Venous irritation associated with the injection of diazepam and lorazepam is secondary to:
B) the presence of propylene glycol as a solvent
The insolubility of diazepam and lorazepam in water requires that parenteral preparations contain propylene glycol, which has been associated with venous irritation. (Nagelhout pg. 135-137, Barash pg. 453)
A block of the sural nerve would produce anesthesia of: (Choose the correct area of the foot)
A block of the sural nerve would produce anesthesia of:
The sural nerve is a continuation of the tibial nerve and enters the foot between the Achilles tendon and the lateral malleolus to provide sensation to the lateral foot. (M&M pg. 352)
The hormones produced by the adrenal gland are shown below. Match the hormone to the site of production in the adrenal gland.
Site of Production
a) Adrenal Medulla
b) Zona Reticularis
c) Zona Glomerulosa
d) Zona Fasciculata
a) Adrenal Medulla - Catecholamines
b) Zona Reticularis - Sex Steroids
c) Zona Glomerulosa - Mineralcorticoids
d) Zona Fasciculata - Glucocorticoids
In the thromboelastograms below, thrombocytopenia is best represented by:
Thrombocytopenia causes an overall reduction in clot strength shown as a narrowing in the thromboelastogram. (Barash pg. 394)
In the graph of cerebral blood flow below, PaO2 would best be represented by curve:
Curve A best represents the effects of changing oxygen tensions on cerebral blood flow. Hypoxemia causes a significant increase in CBF to meet the brain's metabolic demand. Hyperoxia, however, causes little change in CBF. (Barash pg. 1007-1008)