Practice III Flashcards
The majority of the venous return from the myocardium enters the:
- superior vena cava
- great cardiac vein
- coronary sinus
- Thebesian veins
coronary sinus
The great, middle and posterior left cardiac veins as well as the oblique vein of Marshall empty into the coronary sinus. The Thebesian veins, which transverse the myocardium, empty into the various chambers, but constitute only about 15% of the myocardial venous return.
When performing a caudal anesthetic, proper placement of the needle(s) is at:
(Make your selection by clicking on the appropriate area of the figure)
Caudal anesthesia can be thought of as a distal approach to the epidural space. With the patient prone or in the lateral position, the sacral hiatus is identified and a short-beveled needle is inserted midline between the cornua at a steep angle. When the canal is entered, the needle is lowered parallel to the sacrum and advanced into the epidural space.
Concerning intraocular pressure:
- the most significant hemodynamic parameter determining intraocular pressure is arterial blood pressure
- volatile anesthetic agents lower intraocular pressure
- hyperventilation will increase intraocular pressure
- increased PaO2 will lower intraocular pressure
volatile anesthetic agents lower intraocular pressure
Volatile anesthetic agents consistently lower intraocular pressure. The most significant hemodynamic parameter determining IOP is CVP. Hypoxia and hypercarbia both increase IOP, however IOP is not significantly changed by increases in PaO2.
The primary mechanism of heat loss from a patient in the operating suite is:
- evaporation
- convection
- conduction
- radiation
radiation
Radiation accounts for approximately 60% of the heat loss in the surgical patient. Other forms of heat loss in the surgical patient include evaporation (20%), convection (15%), and conduction (5%).
During a laparoscopic cholecystectomy in a 46-year-old female with a history of hypertension, you notice an acute rise in end-tidal carbon dioxide tension associated with a blood pressure of 78/45 mm Hg, and rales. Immediate therapy should include:
- correction of the volume overload with furosemide
- a 500ml bolus of NS
- asking the surgeon to release the pneumoperitoneum
- placement of the patient in reverse Trendelenberg position
asking the surgeon to release the pneumoperitoneum
Carbon dioxide embolism can result from unintentional insufflation of gas into an open vein. This may lead to hypotension, elevated end-tidal carbon dioxide levels, hypoxemia, and pulmonary edema. Treatment consists of immediate release of the pneumoperitoneum.
The polarographic oxygen analyzer is best represented by?
Make your selection by clicking on the appropriate part of the figure
The polarographic oxygen electrode (Clark electrode) consists of a voltage source and a current meter connected to platinum and silver electrodes immersed in a KCl solution. A membrane permeable to oxygen allows the diffusion of oxygen into the cell, where electrons are liberated by an oxidative reaction. The meter measures the current produced, with the current flow being proportional to the oxygen concentration.
A 78-year-old man is scheduled for a right carotid endarterectomy under general anesthesia. The most sensitive method for assessing cerebral perfusion during the procedure is:
- measurement of carotid stump pressures
- measurement of the oxygen content of jugular venous blood
- EEG monitoring
- somatosensory evoked potential monitoring
EEG monitoring
EEG monitoring is the most sensitive method of assessing the adequacy of cerebral perfusion in the anesthetized patient.
Which of the following herbal medications may cause an increase in bleeding during surgery? (Select 2)
- St. John’s wort
- Garlic
- Fish Oil
- Valerian
- Licorice
- Kava
Garlic, Fish Oil
All of the following herbal medications may adversely affect clotting: alfalfa, capsicum, chamomile, dong quai, feverfew, fish oil, garlic, ginkgo biloba, ginger, ginseng, goldenseal, guarana, horse chestnut, and willow bark. These medications should be discontinued for at least two weeks preoperatively. Coagulation studies should be performed in patients who are actively taking these herbals.
Compensatory mechanisms that buffer increases in intracranial pressure include:
- increased cerebrospinal fluid production
- displacement of cerebrospinal fluid into the spinal canal
- increased intracranial venous blood volume
- decreased cerebrospinal fluid absorption
displacement of cerebrospinal fluid in to the spinal canal
Within limits, increases in intracranial volume result in only small increases in intracranial pressure. Major compensatory mechanisms include a displacement of CSF into the spinal canal, increased CSF absorption, decreased CSF production, and decreased cerebral blood volume - mostly venous.
A display of arterial blood gas values is shown (Click here to display values). By dragging & reordering the selections in yellow, match the blood gas values with the corresponding metabolic abnormality.
metabolic acidosis
metabolic alkalosis
respiratory alkalosis
respiratory acidosis
#1 7.20/83/78/32 #2 7.55/97/40/34 #3 7.51/95/28/35 #4 7.22/88/37/15
Respiratory acidosis - #1
Metabolic alkalosis - #2
Respiratory alkalosis - #3
Metabolic acidosis - #4
A list of diuretic sites of action is shown below. By dragging & reordering the selections in yellow, match the diuretic with the corresponding site of action.
Hydrochlorothiazide
Spironolactone
Acetazolamide
Furosemide
Proximal Tubule
Collecting Duct
Loop of Henle
Distal Tubule
Acetazolamide-Proximal Tubule
Furosemide-Loop of Henle
Hydrochlorothiazide-Distal Tubule
Spironolactone-Collecting Duct
Pulse oximetry employs the absorption of two specific frequencies of light by hemoglobin to determine the oxygen saturation. This is an application of:
- Boyle’s Law
- Graham’s Law
- Charles’ Law
- Beer-Lambert Law
Beer-Lambert Law
The Beer-Lambert Law states that: (1) the luminance of perpendicular light on a surface is proportional to the inverse square of the distance it travels; (2) the luminance intensity of angled light is proportional to the cosine of the angle with the normal; (3) Luminance intensity decreases exponentially as the light travels through a medium. Analysis of the wavelength that is most absorbed corresponds to the concentration of that form of hemoglobin.
As compared to the classic LMA, advantages of the LMA ProSeal include:
- the ability to provide active gastric suctioning
- greater ease of insertion
- decreased peak inspiratory pressure
- the absence of a bite block
the ability to provide active gastric suctioning
The LMA ProSeal is a double lumen LMA allowing gastric drainage. In addition, the ProSeal has a bite block and allows a greater peak inspiratory pressure to be delivered.
A display of oxyhemoglobin dissociation curves is shown (Click here to display curves). By dragging & reordering the selections in yellow, match the physiologic state with the corresponding curve.
A
B
C
D
Acidosis
Alkalosis
Myoglobin Curve
Normal Curve
Myoglobin Curve-A
Alkalosis-B
Normal Curve-C
Acidosis-D
On a warm summer day, e-cylinders of oxygen and nitrous oxide are brought from the hospital loading dock into the air-conditioned operating room. The effect of the declining temperature on the e-cylinders is to:
- cause a decrease in tank pressure in both cylinders
- cause a decrease in tank pressure of the oxygen cylinder only
- cause a decrease in tank pressure of the nitrous oxide cylinder only
- cause a decrease in the critical temperature of the oxygen
cause a decrease in tank pressure in both cylinders
Following the Combined Gas Law, a decline in ambient temperature will cause a decrease in both tank pressure and tank volume. Since the critical temperature of oxygen is -118 C, oxygen cannot exist as a liquid at ambient temperatures.
The most common cause of chronic liver disease in the United States is:
- alcoholic cirrhosis
- hepatitis C
- cytomegalovirus
- non-alchoholic fatty liver disease
non-alchoholic fatty liver disease
Non-alcoholic fatty liver disease (NAFLD) is the most common cause of chronic liver disease in the US. It is defined as fat accumulation in the liver exceeding 5% by weight. It has been estimated that 24% of American adults have NAFLD. Risk factors for its development are Type II DM and obesity; it is more prevalent in women, and it usually manifests in the fifth and sixth decades of life.
When using a pulmonary artery catheter to measure thermodilution cardiac output, factors that may cause a falsely elevated measurement include:
- pulmonic valve insufficiency
- aortic insufficiency
- intrapulmonary shunting
- mitral regurgitation
- VSD
pulmonic valve insufficiency, VSD
Recirculation of blood and injectate, in either the right atrium or right ventricle, can cause a falsely elevated measurement of CO. As a result, ASD, VSD, tricuspid regurgitation, and pulmonic regurgitation can cause a falsely elevated measurement of CO.
Post-operative shivering:
- it most commonly seen in the neonatal population
- is best treated with morphine 12.5 mg IV
- may increase O2 consumption and CO2 production by up to 200%
- decreases cardiac output and minute ventilation
may increase O2 consumption and CO2 production by up to 200%
Post-operative shivering may increase O2 consumption and CO2 production by up to 200%. It increases cardiac output and minute ventilation as well, which may precipitate ventilatory failure in patients with limited reserve and myocardial ischemia in patients with CAD. Along with restoration of normothermia, meperidine (12.5-25 mg IV) is most efficacious in suppressing post-operative shivering.
A 28-year-old male is undergoing an emergent laparotomy after sustaining multiple injuries in a motor vehicle accident. As a result of trauma to the inferior vena cava, the patient receives 12 units of packed red blood cells (PRBC’s), 3 units of fresh frozen plasma and 8 units of platelets over the course of an hour. During this period you notice a widening of the QRS complex with lengthening of the QT-interval on the ECG. The most appropriate therapy at this time is to:
- increase the rate of infusion of the PRBC’s
- stop the administration of all blood products
- administer intravenous calcium gluconate
- increase the rate of infusion of NS
administer intravenous calcium gluconate
Stored blood contains citrate to chelate the ionized calcium and prevent coagulation. During rapid infusion, greater than 1cc/kg/min, of blood products, patients can develop hypocalcemia secondary to citrate intoxication. Hypotension and ECG evidence of hypocalcemia, widening of the QRS complex and lengthening of the QT-interval, can be effectively treated with ionized calcium.
Risk factors for pregnancy induced hypertension (PIH) include:
- multiple previous pregnancies
- low blood pressure prior to pregnancy
- diabetes mellitus
- single fetus
diabetes mellitus
PIH is most prevalent in primigravidas. The pathophysiology of this disease is unknown. Additional risk factors include: extremes of maternal age, multiple births, pre-pregnancy hypertension, diabetes mellitus, asthma, renal disease and autoimmune disease.
Advantages of the piston ventilator include (Select 2):
- indentifiable auditory cues during ventilation
- use of air instead of oxygen as a driving gas
- fresh-gas decoupling
- improved accuracy of delivered tidal volume
- decreased dead space
- compensation of gas loss in cases of bellows leak
fresh-gas decoupling, improved accuracy of delivered tidal volume
Advantages of the piston ventilator include: it’s very quiet, no PEEP is applied, fresh-gas decoupling, greater volume precision and no driving gas is required. Disadvantages include: loss of familiar visible behavior of the standing bellows during a disconnect, difficulty in hearing the ventilatory cycle, hypoventilation if a bellows leak occurs and difficulty accommodating non-rebreathing circuits.
An acquired decrease in the level of plasma cholinesterase activity is associated with:
- obesity
- pregnancy
- electroconvulsive therapy
- alcoholism
pregnancy
Pregnancy causes an acquired decrease in plasma cholinesterase activity. Alcoholism, obesity, thyrotoxicosis, hemochromatosis, nephrotic syndrome and electroshock therapy all cause acquired increases in plasma cholinesterase activity.
During your preoperative evaluation, the rhythm strip below is obtained. This ECG tracing is consistent with:
- acute myocardial infarction
- complete heart block
- intraventricular conduction delay
- non-specific ST-T wave changes
intraventricular conduction delay
The QRS duration on the ECG above is greater than 0.12 seconds indicating an intraventricular conduction delay. Although ST - T wave abnormalities are present, they are expected in patients with bundle branch block patterns. Each QRS complex is preceded by a P wave and a PR interval less than 0.20 seconds, indicating no heart block. Since the lead of the tracing is unknown, we cannot determine if this is a left or right bundle branch block pattern.
Dexmedetomidine (Precedex):
- increases the MAC of volatile anesthetics
- causes CNS excitation via selective a-2 agonism
- reduces the incidence of perioperative hypothermia
- has analgesic properties
has analgesic properties
Dexmedetomidine (Precedex) is a more selective α-2 agonist than clonidine. It produces sedation/anxiolysis, it is an antisialagogue, it promotes hemodynamic stability, homeostatic reflexes remain intact, and it is a potent analgesic. It also attenuates opioid-induced rigidity in animals.