Apex Unit 12 Miscellaneous Topics Flashcards

Question

Match each chemotherapeutic agent with its unique side effect.

Answer 1

Cisplatin + Renal toxicity Bleomycin + Pulmonary toxicity Doxorubicin + Cardiac toxicity

Answer 2

Gastrin + Associated with Zollinger-Ellison syndrome Somatostatin + Treatment for carcinoid tumor Cholecystokinin + Produces gallbladder pain after a fatty meal

Answer 3

Ondansetron Ondansetron is a 5-HT3 receptor antagonist. It treats PONV by antagonizing serotonin receptors in two places: Chemoreceptor trigger zone (area postrema) Peripheral receptors in the GI tract and vagus nerve Scopolamine (M1 antagonist) and hydroxyzine (H1 antagonist) primarily target the vestibular apparatus in the inner ear. Dexamethasone binds to intracellular steroid receptors, however its exact site of action is unknown.

Answer 4

End-tidal carbon dioxide The pneumatic tourniquet is used to reduce blood loss during extremity surgery. Cells distal to the tourniquet shift to anaerobic metabolism, and metabolic byproducts accumulate as long as the tourniquet is inflated. Releasing the tourniquet produces transient changes that include: ``` Increased EtCO2 Decreased core body temperature Decreased blood pressure Decreased SvO2 (SaO2 is usually normal) Metabolic acidosis ```

Answer 5

Hypertension Aspirin exacerbated respiratory disease (Samter’s triad) refers to the combination of asthma, allergic rhinitis, and nasal polyps. These patients can develop life threatening bronchospasm following aspirin administration.

Answer 6

``` Licorice + May mimic Conn's syndrome Valerian + Decreases MAC St. John's Wort + Serotonin syndrome with MAOIs Garlic + Increases bleeding ``` Herbal medications have perioperative implications including effects on bleeding, synergism with other agents, cardiovascular instability, and metabolic derangements. We’ll cover the essentials on the next page.

Answer 7

Food and Drug Administration + Food and drugs United States Department of Transportation + Compressed gas cylinders Occupational Safety and Health Administration + Acceptable occupational exposure to volatile anesthetics American Society for Testing and Materials + Required components of the anesthesia machine

Answer 8

Postoperative nausea and vomiting ``` The modified Aldrete scoring system is used to quantify readiness for discharge from the PACU. It assesses five areas: Activity Respiration Circulation Consciousness Oxygen saturation ``` PONV is not assessed by the modified Aldrete scoring system.

Answer 9

Nine Each gram of fat provides nine calories. If unused, the body will store these excess calories as adipose. By comparison, a gram of carbohydrate provides four calories and a gram of protein provides four calories.

Answer 10

22.59 or 22.64 kg/m2 We accepted a range to account for different ways of calculating BMI. 1. Convert weight from pounds to kilograms. (Conversion = lbs / 2.2) 176 lbs / 2.2 = 80 kg 2. Convert height from inches to centimeters. (Conversion = in x 2.54) 74 inches x 2.54 = 187.96 cm 3. Convert centimeters to meters. (Conversion = cm / 100) 187.96 cm / 100 = 1.8796 m 4. BMI = kg / m squared 80 kg / 1.8796 m squared = 80 / 3.53289616 = 22.64

Answer 11

52 – 58 The ideal body weight for this patient is 55 kg. ``` IBW men (kg) = Height (cm) - 100 IBW women (kg) = Height (cm) - 105 ``` We understand there are some other formulas for the IBW calculation, so we accepted a range of answers (52 – 58).

Answer 12

Vital capacity Expiratory reserve volume Obesity creates a restrictive ventilatory defect. In effect, this compresses the lungs and reduces lung volumes. FRC decreases (ERV decreases and RV remains constant). Closing volume is increased. Vital capacity is decreased.

Answer 13

6 – 8 mL/kg ideal body weight The lungs do NOT grow in proportion to body mass, so the morbidly obese patient should receive a tidal volume 6 – 8 mL/kg of ideal body weight. A higher respiratory rate may be required to maintain PaCO2. Higher tidal volumes only minimally increase PaO2 and may cause shear stress on the lungs.

Answer 14

Diastolic dysfunction Increased venous return The expansion of intravascular blood volume is one of the key changes that lead to the cardiovascular complications of obesity. Increased circulating volume augments venous return (preload) and consequently myocardial wall stress. The heart compensates by becoming thicker, however this occurs at the expense of myocardial relaxation. This causes diastolic dysfunction. Heart rate is usually unchanged (not increased) in the obese patient. An increased stroke volume is responsible for the increased cardiac output. The EKG voltage is typically reduced (not increased) because the fat mass increases the distance between the heart and the skin leads.

Answer 15

Volume of distribution of lipophilic drugs Volume of distribution of hydrophilic drugs This one may be a bit tricky, but it builds on several important concepts from the last question. The Vd of lipophilic drugs is increased due to a larger fat mass. The Vd of hydrophilic drugs is increased due to a larger muscle mass and blood volume. A higher cardiac output hastens IV drug delivery to the site of action. This shortens circulation time. MAC is unchanged.

Answer 16

Succinylcholine Midazolam The initial doses of succinylcholine and midazolam should be based on total body weight. The initial doses of propofol and remifentanil should be based on lean body weight. Before moving to the next page, can you think of why this is?

Answer 17

Thyroarytenoid There are three sets of muscles that dilate the upper airway. You should know the primary function for each one. ``` Tensor palatine (opens nasopharynx) Genioglossus (opens oropharynx) Hyoid muscles (opens hypopharynx) The thyroarytenoid muscles relax the vocal cords. ```

Answer 18

12 The apnea/hypopnea index helps quantify the severity of OSA. This value is derived by the number episodes of apnea and hypopnea divided by the total hours of sleep. ``` Mild = 5 – 15 episodes/hr Moderate = 15 – 30 episodes/hr Severe = > 30 episodes/hr ```

Answer 19

Obesity hypoventilation syndrome Okay, maybe this question is unfair for those of you who don’t read classic British literature. Who has time for that? Having said this, you should be able to deduce the answer from the title, “The Pickwick Papers.” Pickwick…Pickwickian syndrome…another name for obesity hypoventilation syndrome…you get the idea.

Answer 20

Unexplained tachycardia Unexplained tachycardia is the most sensitive sign of an anatomic leak following gastric bypass. Abdominal pain, shoulder pain, and fever are additional signs of an anastomotic leak, however they are not the most sensitive.

Answer 21

Ma huang + Ephedra alkaloid Phentermine + Norepinephrine reuptake inhibitor Sibutramine + Norepinephrine and serotonin reuptake inhibitor Orlistat + Lipase inhibitor

Answer 22

Reduces pulmonary compliance Increases the risk of endobronchial intubation Just as gravity affects the distribution of blood volume in the anesthetized patient, it also affects the position of the abdominal viscera. When the patient is placed into the Trendelenburg position, the abdominal viscera shift toward the thorax. This has several consequences: The diaphragm moves cephalad (not caudad). FRC is reduced (not increased). Pulmonary compliance is decreased. The risk of endobronchial intubation is increased.

Answer 23

Arms tucked at side + non-sliding mattress Surgical positioning for robotic assisted laparoscopic radical prostatectomy requires steep Trendelenburg position. To minimize the risk of brachial plexus injury, the arms should be tucked at the patient’s sides and he should be positioned on a non-sliding mattress. Shoulder braces increase the risk of brachial plexus injury.

Answer 24

Ulnar The ulnar nerve is the most commonly injured peripheral nerve. Although its anatomy renders it susceptible to compression, it's critical to understand that this isn't the only cause of ulnar neuropathy that develops during hospitalization. Presentation may include: Impaired sensation of the fourth and fifth digits Inability to ABduct or oppose the pinky finger Chronic injury presents with claw hand (muscular atrophy)

Answer 25

Median Although median nerve injury is a rare event, it can occur as a result of traumatic IV insertion at the antecubital space.

Answer 26

Radial The radial nerve passes along the spiral groove at the lateral aspect of the humerus (about 3 fingerbreadths above the lateral epicondyle). ``` It can be injured by: External compression by an IV pole Excessive cycling of the NIBP cuff Upper extremity tourniquet Sheets that are too tight (if the arms are tucked) ```

Answer 27

Common peroneal The common peroneal nerve is highly susceptible to injury when the patient is placed in stirrups. This nerve wraps around the fibular head, and it can be compressed when the lateral aspect of the leg leans against the stirrup bar. Presentation of common peroneal nerve injury: Foot drop Inability to evert the foot Inability to extend the toes dorsally

Answer 28

Midcervical tetraplegia Paradoxical air embolism Midcervical tetraplegia is associated with hyperflexion of the neck (chin to chest). Ischemia occurs as a result of stretching and/or compression of the midcervical spinal cord (usually C5). This complication is most common in the sitting position. Although the sitting position is most commonly associated with venous air entrainment, this complication can occur in any position that produces a pressure gradient between the atmosphere and the veins at the surgical site.

Answer 29

Code of Ethics The AANA Code of Ethics dictates the principles of conduct and professional integrity that guide the decision making and behavior of nurse anesthetists. This document speaks to the anesthetist’s responsibilities as a professional, which holds the individual CRNA accountable for his or her own actions and judgments, regardless of institutional policy or physician orders. As a professional, the CRNA is held individually accountable for his or her “conduct in maintaining the dignity and integrity of the profession” and “does not knowingly engage in deception in any form.” The specific act committed by the CRNA in this question is called libel.

Answer 30

Nonmaleficence Nonmaleficence asserts that a provider has an obligation not to inflict hurt or harm—in other words, the Hippocratic oath primum non nocere (first do no harm). There is no distinction between intentional or unintentional harm. The use of unnecessary preoperative testing can put the provider in violation of the principle of nonmaleficence.

Answer 31

Risks and benefits of each type of appropriate anesthetic Patient preferences, questions, and fears Informed consent conversations should include a discussion of all available and appropriate anesthetic choices for both the particular surgery/procedure and relevant comorbidities. The preoperative consent process should allow for open sharing of information regarding anesthetic care and focused on the patient’s concerns, needs, and questions. It is recommended that the anesthesia consent process and paperwork should be separate and apart from the surgical consent process; further, the only appropriate person to conduct the anesthesia informed consent is the anesthesia provider.

Answer 32

Determine that patient has sufficient capacity Despite the pain and distress that may accompany active labor, research has shown that most women retain the ability to understand, assimilate information, and make decisions. However, capacity is one of the elements of consent and should be ascertained as part of the informed consent process (review the last page if this doesn’t make sense). It should go without saying that a current H&P, labor progress, and the effectiveness of current analgesia are all important parts of the pre-anesthetic evaluation process.

Answer 33

Standard four on informed consent and related anesthesia services Reconsideration of a pre-existing advanced directive is a critical component of the informed consent process, because some events that may occur are responses to the anesthetic and are not part of the terminal disease process. Advance directives should not be routinely suspended perioperatively, but require a detailed discussion as noted in this lesson.

Answer 34

Wellness Infection Control and Prevention Transfer of Care Only three of the answer choices are standards published by the AANA (listed above). These standards represent the expected behaviors that must be demonstrated in a professional practice and that “must” be adhered to. These are the standards against which the delivered care is compared in the event of a lawsuit. Failure to adhere to these standards will provide prima facie evidence of negligence. The AANA publications on latex allergy, chronic pain, and mass casualty incident management are practice guidelines—suggestions that “should” be adhered to but that do not rise to the level of standards.

Answer 35

Malpractice violation of the AANA standards of care Abandonment Standard 11 relates to the accurate reporting of a patient’s condition which is defined as, " Evaluate the patient’s status and determine when it is appropriate to transfer the responsibility of care to another qualified healthcare provider. Communicate the patient’s condition and essential information for continuity of care." A plaintiff attorney may also claim abandonment—the transfer of care, although to a qualified provider, was incomplete in not addressing the requirement for a repeat dose of antibiotic. Thus, the duty to the patient was abandoned. Vicarious liability and loss of chance of survival will be defined shortly.

Answer 36

Emergency in Medical Treatment and Active Labor Act There are 6 federal laws that significantly affect health care practice in the United States. Deciphering these laws and their acronyms is the object of Parts I and II of the next lessons.

Answer 37

Schedule I + Heroin Schedule II + Cocaine Schedule III + Ketamine Schedule IV + Tramadol

Answer 38

Describe the facts of the event while also expressing regret It is now generally accepted that the relationship between the anesthesia provider and the patient-family should be based on honesty and trust. Disclosure of actual events early reinforces this relationship of trust. Disclosure of facts does not pose any greater threat to the providers because the patient and family will inevitably discover them in the future. There is evidence that the “disclosure, apology, and offer” approach to adverse events versus the “deny and defend” approach reduces claims, settlement amounts, and defense costs. All providers should ensure that they are aware of their institutional or group policies as well as state law on these matters.

Answer 39

Evidence of duty, breach, cause, and harm More likely than not that negligence occurred A claim of malpractice must prove that the defendant had a duty to the patient, the defendant breached their duty, a causal relationship exists between the defendant’s acts and the patients’ injury, and damages resulted from the breach. With this in mind, absolute certainty of malpractice is NOT required. A jury may find for the plaintiff if they believe that the probability of causal injury is greater than 50%. Further, the defense need only prove an acceptable, not the highest, standard of care was provided.

Answer 40

1 + Death 2 + Nerve damage 3 + Permanent brain damage 4 + Awareness

Answer 41

Delay surgery until the child is mature enough to join in the decision-making process. In elective cases, it is appropriate to wait for the pediatric patient to reach a sufficient age and maturity, and then allow them to participate in the decision-making process.

Answer 42

Providers are rewarded for erring on the side of caution even if wrong. Explicit communication is frequent and ambiguity is challenged. Workplace culture can make or break efforts to improve patient care and increase patient safety. A culture of safety is cultivated in several ways, which we’ll discuss on the next page.

Answer 43

Communication In an anesthetic crisis, effective response and management is dependent upon non-technical skills. Crisis resource management (CRM) uses a simple model in which effective communication is the “glue” that holds all the other components together.

Answer 44

70% The 70% human error rate is comparable to our parallel professionals—aviators—in terms of the high cognitive demands, multitasking, and the need for constant vigilance. Work in both professions challenges individuals both physiologically and mentally; for this reason, maintenance of personal health and wellness is absolutely required.

Answer 45

Get a consistent 8 hours of sleep each night As noted in the previous lesson, sleep debt will accumulate until the debt is directly paid. No countermeasures can reduce sleep debt; however helpful guidelines for managing fatigue at work are next!

Answer 46

5 rem The OSHA limit for occupational exposure to ionizing radiation is 5 rem annually, with a lifetime limit of (N-18) x 5 rem, N= age in years. In this provider, the lifetime limit will be reached at 100 rem.

Answer 47

Tolerance + Markedly diminished effects of the same drug amount Impairment + An inability to engage in activities of daily living Withdrawal + Physical and emotional responses to very low drug levels

Answer 48

Intense emotional response to a medical error It’s important to recognize that just because a person exhibits signs and symptoms of substance abuse disorder, doesn’t mean that it’s the only explanation for this behavior. For instance, someone could work a lot of overtime as she saves for a down payment on a home or someone else might be emotionally labile and moody because he’s going through a divorce. Having said this, we must be aware of these changes in our co-workers. Furthermore, the more signs or symptoms someone demonstrates, the more we should pay attention. An intense emotional response to a medical error is a natural (and expected) human response in even the healthiest of individuals.

Answer 49

Improve patient experience Improve population health Reduce per capita costs The “Triple Aim” is a conceptual approach to improving the US health care system “aiming” at three primary areas: care, health, and cost. Care involves improving patient experience and includes both delivered healthcare quality and patient satisfaction. Improving overall population health affects both individual health and reduces the societal burden of a chronically ill population Reduced per capita costs references the fact that the US has the most expensive healthcare system in the developed world while also being ranked among the worst for efficiency, equity, and outcomes.

Answer 50

Covalent The atom is the building block of matter, and 2 or more atoms bonded together is called a molecule. Molecular bonding occurs when valence electrons of one atom interact with the valence electrons of another atom. There are 4 types of atomic bonds you should know: 1. Ionic bond: Involves the complete transfer of valence electron(s) from one atom to another. This creates ions. 2. Covalent bond: Involves the sharing of electrons. 3. Polar covalent bond: Involves the sharing of electrons, but the electrons tend to remain closer to one of the atoms (creates a partial negative charge) and further away from another atom (creates a partial positive charge). 4. Van der Waals forces: Van der Waals' forces describe a very weak intermolecular force that holds molecules of the same type together. Electrons (and their negative charges) orbiting a molecule are in constant motion. This creates temporary partial (+) and (-) charges at different parts of the molecule at any given time. The net result is that electron rich areas of one molecule will be attracted to electron poor areas of another molecule. Recap: Molecular bonds in decreasing order of strength: Covalent > Ionic > Polar covalent > Van der Waals

Answer 51

Five percent Dalton's law of partial pressures says that the total pressure is equal to the sum of the partial pressures exerted by each gas in the mixture. P total = P1 + P2 + P3... The question asked you to convert the partial pressure of desflurane to volumes percent. Here's the equation: Volumes percent = (Partial pressure / Total pressure) x 100 Et Des = 38 mmHg P atm = 760 mmHg (38 mmHg / 760 mmHg) x 100 = 5%

Answer 52

22.8 mmHg The question is just like the last one, but we're going the other direction. Here's how to convert volumes percent to partial pressure: Partial pressure = Volumes percent x Total pressure Vol% sevo = 3% P atm = 760 mmHg 3% x 760 mmHg = 22.8 Instead of a volatile agent, you might be asked about carbon dioxide or any other gas. The concept is the same no matter what gas you're asked about.

Answer 53

433 mmHg (we also accepted 429 and 436 mmHg) This is another application of Dalton's law. O2 FGF = 1 L/min (this is 1/3 of total FGF) N2O FGF = 2 L/min (this is 2/3 of total FGF) P atm = 650 mmHg (this is the same as P total) If the total FGF is 3 L/min and N2O is 2 L/min, then the FiN2O is 66% or 2/3. Next, you need to multiply the total pressure (P atm) by 2/3 to arrive at the correct answer. N2O at 2 L/min x (2/3 x 650 mmHg) = 433 mmHg If you used 0.66, then the correct answer is 429. If you used 0.67, then the correct answer is 436.

Answer 54

Henry’s Law Henry's Law states that the amount of gas that dissolves in solution is directly proportional to the partial pressure of that gas over the solution. If we significantly increase the concentration of volatile anesthetic at the alveolocapillary interface, we can hasten its transfer into the bloodstream and ultimately the brain. This technique is called “overpressurizing" the vaporizer.

Answer 55

gay lussac You're expected to understand which variables remain constant in each gas law, and the mnemonic "Paid TV Can Be Great" can help you. The top row of boxes contains the variables and the bottom row contains the gas laws. The red variable directly above each gas law is NOT included in that law, while the green variables are included in that particular law. Gay-Lussac's law says that pressure and temperature are directly proportional when the volume is held constant.

Answer 56

1167 mmHg This is an application of Boyle's law: P1 x V1 = P2 x V2 ``` P1 = 700 mmHg V1 = 500 mL P2 = X V2 = 300 mL Here's the calculation: (700 mmHg x 500 mL) = (X mmHg x 300 mL) X = 1167 mmHg As a secondary way to check your calculation, you should conceptually determine the directional change of the unknown variable. If the direction of change doesn't match your prediction, then you'll want to double-check your equation and/or calculation. ```

Answer 57

Boyle's law + Diaphragm contraction increases tidal volume Charles's law + An LMA cuff ruptures when placed in an autoclave Gay-Lussac's law + Oxygen tank explodes in a heated environment Boyle's law (P x V = constant): Diaphragm contraction increases tidal volume Pneumatic bellows Squeezing an ambu bag Using the bourdon pressure gauge to calculate how much O2 is left in a cylinder (assumes a given flow rate). Charles's law (V / T = constant): LMA cuff ruptures when placed in an autoclave Gay-Lussac's law (P / T = constant): Oxygen tank explodes in a heated environment

Answer 58

760 mmHg This question wasn't designed to trick you, but rather we want to make sure that you understand a few critical concepts. 1. The Bourdon pressure gauge measures tank pressure relative to atmospheric pressure. Therefore, if the gauge reads 0 mmHg, the pressure in the tank is actually the same as atmospheric pressure (760 mmHg at sea level). 2. And this brings us to our next point. Gas moves according to a pressure gradient. If the pressure inside the tank is 760 mmHg and the atmospheric pressure is also 760 mmHg, the small volume of gas that remains in the tank will remain inside the tank since there is no driving pressure to push it out (760 mmHg - 760 mmHg = 0).

Answer 59

16 The Poiseuille equation describes the laminar flow through a tube. Q = π R^4 ∆P / 8 η l Flow = 3.14 x Radius ^4 x Pressure difference / 8 x viscosity x length As you can see, the radius of the tube exhibits the greatest impact on flow. ``` R = 1^4: 1 x 1 x 1 x 1 = 1 R = 2^4: 2 x 2 x 2 x 2 = 16 R = 3^4: 3 x 3 x 3 x 3 = 81 ```

Answer 60

Poiseuille's law Poiseuille's law describes the variables that govern laminar flow. Q = πr^4 ∆P / 8ηl Flow is directly proportional to: Driving pressure Radius^4 (increasing R is the best way to improve flow) ``` Flow is inversely proportional to: Viscosity Length of the tube If we apply these concepts to the question, then we can see that flow is increased when a wider endotracheal tube is s ```

Answer 61

Viscosity Reynold's number helps us predict the type of flow that will occur in a given location. Re = (fluid velocity x fluid density x tube diameter) / (fluid viscosity) Laminar: Re < 2,000 Transitional: Re = 2,000 - 4,000 Turbulent: Re = > 4,000 Laminar flow is more dependent on fluid viscosity. Turbulent flow is more dependent on fluid density.

Answer 62

Reynold's number Because turbulent flow is primarily dependent on gas density, we can improve flow by having the patient inhale a lower density gas. An oxygen/helium mixture (Heliox) decreases Reynold's number and can improve airflow when airway resistance is high. A helium/oxygen mixture is also useful for the patient with epiglottitis. Helium does NOT improve flow if it is already laminar

Answer 63

Henry Graham Fick's law of diffusion describes the transfer rate of gas through a tissue medium. The rate of transfer is DIRECTLY proportional to: Partial pressure difference (driving force) Diffusion coefficient (solubility) Membrane surface area The rate of transfer is INVERSELY proportional to: Membrane thickness Molecular weight Applications of the Fick equation: Diffusion hypoxia A patient with COPD has a reduced alveolar surface area, and therefore has a slower rate of inhalation induction Calculation of cardiac output Henry's law and Graham's law are incorporated into the Fick equation. Henry's law states that the amount of gas that dissolves in solution is directly proportional to the partial pressure of that gas over the solution. Graham's law states that the rate of gas diffusion is inversely proportional to the square root of its molecular weight.

Answer 64

Law of Laplace The ventricle develops wall tension to overcome afterload, and we can apply the law of Laplace to give us deeper insight into this process. Wall Tension = (LV Pressure x Radius) / (LV Wall Thickness x 2) ``` From this equation you can see that wall tension (wall stress) is reduced by: ↓ Intraventricular pressure ↓ Radius ↑ Wall thickness ``` The law of Laplace also helps us understand why the patient with systemic hypertension compensates with left ventricular hypertrophy - A thicker left ventricle reduces wall stress.

Answer 65

Six feet Radiation exposure obeys the inverse square law, which says the amount of exposure is inversely proportional to the square of the distance of the source. Intensity = 1 / Distance ^2 The minimum recommended distance from an ionizing radiation source is 6 feet.

Answer 66

Carbon dioxide We're sure that nitrous oxide immediately came to mind. Remember, you won't always see the obvious answer on boards. Critical temperature is the highest temperature where a gas can exist as a liquid. Said another way, it is the temperature above which a gas cannot be liquefied regardless of the pressure applied to it. The critical temperature for carbon dioxide is 31 C, which explains why it primarily exists as a liquid inside the cylinder (Room temperature is about 20 C). Conversely, the critical temperature of oxygen is -119 C, so it exists as a gas inside the cylinder. Critical temperatures of common gases (highest to lowest): Nitrous oxide = 36.5 C (liquid in the cylinder at room temp) Carbon dioxide = 31 C (liquid in the cylinder at room temp) Oxygen = -119 C Air = -140 C Nitrogen = -147 C

Answer 67

Temperature In a closed container, molecules from a volatile liquid escape the liquid phase and enter the gas phase. The molecules in the gas phase exert a pressure on the walls of the container. This is called vapor pressure. Vapor pressure is primarily dependent on the liquid's temperature: ↑ Temp → ↑ VP ↓ Temp → ↓ VP At body temperature, the vapor pressure of water is 47 mmHg. This is why you see this number subtracted in the alveolar gas equation. Altitude does NOT affect vapor pressure.

Answer 68

Joule-Thompson effect The Joule-Thompson effect says that a gas stored at high pressure that is suddenly released escapes from its container into a vacuum. It quickly loses speed as well as a significant amount of kinetic energy, resulting in a fall in temperature. This explains why an oxygen cylinder that is opened quickly feels cool to the touch (Joule is cool). Conversely, rapid compression of a gas intensifies its kinetic energy, causing the temperature to rise. Adiabatic process describes a process that occurs without gain or loss of energy (heat). For example, a very rapid expansion or compression of a gas where there is no transfer of energy is an example of an adiabatic process.

Answer 69

100.9 F Converting between Celsius and Fahrenheit requires a conversion factor (5/9 or 1.8). To review the "why" you may wish to revisit the Chemistry & Physics Tutorial. Celsius = (F – 32) x 5/9 Fahrenheit = (C x 1.8) + 32 Question: Convert 38.3 C to Fahrenheit. F = (38.3 x 1.8) + 32 = 68.94 + 32 = 100.94 F

Answer 70

13.6 mmHg You should be able to covert to the common units of pressure. All of the following are equal: 1 atm = 1 bar = 760 mmHg = 760 torr = 100 kPa = 1033 cm H2O To solve the calculation, you'll need to convert mmHg to cm H2O then multiply by 10 mmHg. (1033 cm H2O / 760 mmHg) x 10 mmHg = 13.6 cm H2O

Answer 71

Radiation Radiation is the #1 source of heat loss. Radiation > Convection > Evaporation > Conduction

Answer 72

Distal quarter The esophageal temperature probe should be placed in the distal 1/3 - 1/4 of the esophagus (38 - 42 cm past the incisors). If the probe is placed too proximal, the cooling effect of inspiratory gas falsely decreases the temperature measurement. If the probe is placed in the stomach, heat created by liver metabolism falsely increases the temperature measurement.

Answer 73

5 - 7 percent Oxygen consumption is reduced by 5 - 7% for every 1 degree C reduction in body temperature. ``` Induced hypothermia may be useful during: Cerebral ischemia (stroke) Cerebral aneurysm clipping Traumatic brain injury Cardiopulmonary bypass Cardiac arrest Aortic cross clamping Carotid endarterectomy ```

Answer 74

Polyvinyl chloride endotracheal tubes are flammable The cuff is the most vulnerable component of the endotracheal tube Why are the other answers wrong? Laser resistant tubes do NOT have laser resistant cuffs! Laser reflective tape is no longer advised. It's smarter to use a laser resistant ETT

Answer 75

20 mmHg Abdominal compartment syndrome is defined as intraabdominal pressure > 20 mmHg (transduction of bladder pressure) and evidence of organ dysfunction (hemodynamic instability, oliguria, increased PIP). This condition is usually the result of aggressive fluid resuscitation. Treatment includes neuromuscular blockade, sedation, diuresis, and abdominal decompression via laparotomy.

Answer 76

Bradycardia The seizure produced by ECT causes a predictable physiologic response. Tonic phase: Increased PNS tone (bradycardia, hypotension) Clonic phase: Increased SNS tone (increased CBF, ICP, HR, BP, and IOP)

Answer 77

Hyperthermia is a sign Dantrolene is a treatment You must be able to compare and contrast neuroleptic malignant syndrome and malignant hyperthermia. Key facts about NMS: No genetic link. Slower onset (24 - 72 hours). Is caused by dopamine antagonists and antipsychotic drugs. Presents with muscle rigidity, hyperthermia, and tachycardia (like MH). Is treated with dantrolene (like MH) or bromocriptine (not like MH).

Answer 78

Amitriptyline + Tricyclic antidepressant Venlafaxine + Selective norepinephrine reuptake inhibitor Citalopram + Selective serotonin reuptake inhibitor Antidepressants are used in the treatment of chronic pain. Pain modulation occurs in the spinal cord. In the setting of central sensitization, the efficacy of the descending inhibitory pain pathway is impaired. Recall that this pathway uses norepinephrine and serotonin as inhibitory transmitters, so it makes sense that antidepressants that increase the concentrations of these neurotransmitters can treat chronic pain.

Answer 79

Celiac plexus block + Liver cancer Superior hypogastric block + Uterine cancer Thoracic paravertebral block + Breast cancer Thoracic paravertebral block: Local anesthetic injected into the paravertebral space (a potential space) targets the ventral ramus of the spinal nerve as it exits the vertebral foramen. Used for post-op pain relief following mastectomy. Celiac plexus block: The celiac plexus innervates the upper abdominal viscera (except the left side of the colon). Used for cancer pain involving the upper abdominal organs. Superior hypogastric plexus block: The superior hypogastric plexus innervates the pelvic organs. Used for cancer pain involving the pelvic organs.

Answer 80

Vancomycin Previous literature suggested a high rate of cross-reactivity between PCN and cephalosporins (up to 10 percent). These numbers are grossly overstated (due to contamination during the manufacturing process). The likelihood of cross-reactivity is based on the R1 side chain, and the true rate is < 1%. Third and fourth generation cephalosporins are associated with the lowest rate of cross-reactivity (very rare). If a patient reports an allergy to PCN, then s/he may receive a cephalosporin if the reaction: Was NOT IgE mediated (anaphylaxis, bronchospasm, urticaria). Did NOT produce exfoliative dermatitis (Stevens-Johnson syndrome). If the patient experienced any of these complications, then vancomycin or clindamycin are acceptable alternatives.

Answer 81

Encephalopathy Prion disease can lead to encephalopathy and dementia. Creutzfeldt-Jakob disease is the classic example. Etiologies include: Consumption of contaminated animal protein Contaminated implants (corneal or dural tissue) Cadaveric pituitary hormone supplementation

Answer 82

Succinylcholine ``` The most common causes of perioperative anaphylaxis are: #1 Neuromuscular blockers (succinylcholine is most common) #2 Latex #3 Antibiotics (beta-lactams are most common) ```

Answer 83

Bleomycin Bleomycin is associated with pulmonary toxicity. To prevent complications (pulmonary fibrosis), FiO2 should be maintained < to 30 percent. Doxorubicin is associated with cardiotoxicity. Vincristine is associated with peripheral neuropathy. Cisplatin is associated with acoustic nerve injury and nephrotoxicity

Answer 84

Metoclopramide Gastric barrier pressure is the difference of lower esophageal sphincter pressure and intragastric pressure. A lower gastric barrier pressure is associated with a greater likelihood of gastroesophageal reflux. Metoclopramide increases barrier pressure as a function of increased LES tone. Barrier pressure is reduced by glycopyrrolate, pregnancy, and cricoid pressure

Answer 85

Long surgical duration Laparoscopic procedures Previous episodes of PONV Patient risk factors: Female gender (effects of progesterone and/or estrogen on CTZ) Nonsmoker History of motion sickness Previous episodes of PONV Age is loosely associated (youth > old age) Surgical risk factors: ``` Long surgical duration (more time for lipophilic drugs to accumulate) GYN procedures Laparoscopy Breast Plastics Ear Eye Anesthetic risk factors: Halogenated anesthetics Nitrous oxide (> 50%) Opioids Etomidate Neostigmine ```

Answer 86

Aprepitant + Neurokinin-1 antagonist Promethazine + Phenothiazine Droperidol + Butyrophenone Granisetron + 5-HT3 antagonist Neurokinin-1 antagonists: Receptor: NK-1 Ligand: substance P Example: aprepitant ``` Phenothiazines: Receptors: H1 and M1 Ligands: histamine and acetylcholine Examples: promethazine, prochlorperazine, chlorpromazine Butyrophenones: Receptor: D2 Ligand: Dopamine Examples: droperidol, haloperidol 5-HT3 antagonists: Receptor: 5-HT3 Ligand: serotonin Examples: granisetron, ondansetron, dolasetron ```

Answer 87

Glycopyrrolate Pregnancy The likelihood of gastroesophageal reflux is determined by barrier pressure. The higher the barrier pressure, the lower the likelihood of reflex. Barrier pressure = Lower esophageal sphincter pressure - Intragastric pressure Barrier pressure is reduced by: Decreased LES tone Increased intragastric pressure Anticholinergics reduce barrier pressure. This effect lasts ~ 60 minutes with glycopyrrolate and ~ 40 minutes with atropine. Pregnancy reduces barrier pressure. This is probably a combined effect of progesterone (chemical change) and increased abdominal and gastric pressures caused by the gravid uterus. Metoclopramide increases barrier pressure by increasing lower esophageal sphincter tone. It also increases gastric motility, making it a useful option for patients presenting for cesarean delivery. Succinylcholine increases LES tone but it also increases intragastric pressure. These cancel each other out, which is why succinylcholine has no effect on barrier pressure.

Answer 88

Headache Ondansetron is a 5-HT3 receptor antagonist. It does not interact with histamine, dopamine, cholinergic, or NK-1 receptors. Headache and diarrhea are the most common side effects associated with ondansetron. 5-HT3 antagonists (including ondansetron) cause QTc prolongation, however this is not the most common side effect. Droperidol also prolongs the QTc. Extrapyramidal symptoms can occur with metoclopramide and droperidol since these drugs antagonize dopamine in the CNS.

Answer 89

Scopolamine Dimenhydrinate Motion induced nausea is the result of muscarinic receptor stimulation (M1) in the vestibular system of the inner ear. Therefore, drugs that antagonize the M1 receptor (scopolamine and dimenhydrinate) provide relief, while those that target other receptors (ondansetron - 5-HT3 antagonist) and dexamethasone (intracellular steroid receptors) are not helpful for this population. Dimenhydrinate (Dramamine) antagonizes H1 and M1 receptors in the vestibular system.

Answer 90

M1 The vomiting center is located in the nucleus tractus solitarius, (medulla). It receives and integrates input from the chemoreceptor trigger zone, vestibular system, and GI tract. The cerebral cortex also provides afferent input. The chemoreceptor trigger zone (CTZ) resides in the area postrema at the caudal end of the forth ventricle. The blood-brain barrier is poorly developed here, so the CTZ is sensitive to nausea-inducing chemicals and toxins in the systemic circulation. Neurotransmission between the CTZ and the vomiting center involves: Serotonin (5-HT3 receptor) Dopamine (D2 receptor) Substance P (NK-1 receptor) There are no muscarinic receptors in the CTZ The vestibular system is stimulated by acetylcholine (M1 receptor) and histamine (H1 receptor). The GI tract uses serotonin (5-HT3 receptor) and substance P (NK-1 receptor) to communicate with the vomiting center.

Answer 91

NK-1 receptor antagonist NK-1 receptors are located in the GI tract and the vomiting center in the brain. Substance P is the ligand for the NK-1 receptor. Aprepitant: Has no sedative qualities. Does not prolong the QTc. Is available in a PO formulation.

Answer 92

Vagus nerve Nucleus tractus solitarius 5-HT3 receptor antagonists treat PONV in the peripheral and central nervous systems. They act peripherally by blocking 5-HT3 receptors on vagal afferents from the stomach and small intestine. They act centrally by blocking 5-HT3 receptors in the chemoreceptor trigger zone. 5-HT3 receptors are not located on the lower esophageal sphincter or the vestibular system.

Answer 93

Is best applied before the induction of anesthesia The transdermal scopolamine patch is placed in the postauricular area (behind the ear). It is best applied before > 4 hours prior to the induction of anesthesia. It delivers a dose of 5 mcg/hr for ~ 72 hours. Because this is a smaller dose than the intravenous formulation, it's not associated with the same side effect profile (anticholinergic effects). If the patient removes the patch and then touches his or her eye, it will cause mydriasis (pupil dilation). While it's only temporary, it's an inconvenience for the patient.

Answer 94

4 g Acetaminophen is a centrally acting, non-NSAID analgesic. The exact mechanism of action is unclear, however it's been suggested that it inhibits prostaglandin synthesis (COX-3 inhibition?). Additionally, analgesia may be produced by activating the descending inhibitory pain pathway in the spinal cord. Acetaminophen is the most common cause of liver failure in the US. The max dose is 4 g per day.

Answer 95

Normal BMI = Weight in Kgs / Height in meters squared This patient is of normal weight. His BMI is 23 Kg/m2. ``` Underweight: < 18.5 Normal (IBW): 18.5 – 24.9 Overweight: 25 – 29.9 Class I Obesity: 30 – 34.9 Class II Obesity: 35 – 39.9 Obesity class III (severe/morbid): > 40 ```

Answer 96

Increased cardiac output Increased blood volume Increased renal clearance ``` Obesity is associated with an increased: Blood volume Cardiac output Renal clearance Vd lipid soluble drugs ``` ``` Obesity is associated with a decreased: Total body water Pulmonary function Obesity is associated with altered: Plasma protein binding Liver function ```

Answer 97

Remifentanil Propofol While it's true that opioids are highly lipophilic and have large volumes of distribution, the behavior of remifentanil is unique. Since it is rapidly cleared by non-specific plasma esterases (not pseudocholinesterase), it behaves like it's a low Vd drug. For this reason it is dosed on lean body weight (LBW = IBW x 1.3). The loading dose for propofol is based on LBW. It's termination of action is due to redistribution from the plasma into the peripheral compartment (not clearance). Even though succinylcholine is a water soluble drug, the loading dose is based on TBW. This is a clear exception to the rule for water soluble drugs, and we all know that the NCE likes to test the exceptions! Shortly stated, the combination of increased plasma volume (↑ Vd) and increased pseudocholinesterase activity (↑ clearance) necessitates that a higher dose is used to achieve adequate muscle relaxation for tracheal intubation. The texts seem to agree that midazolam should be administered based on TBW, citing a large central volume of distribution. Dosing in this way prolongs the elimination t1/2. Clinically this may result in over sedation in a population already sensitive to respiratory depressant drugs.

Answer 98

50 mL/kg Although the total blood volume is increased in the morbidly obese patient, the percentage of total blood volume relative to the patient's weight is actually decreased. Adipose isn't as vascular as lean tissue, so it contributes less total body water on a per weight basis. The patient with a normal BMI has a TBW of 60%, while the patient with class III obesity has a TBW of ~ 40 percent. ``` The patient with a normal BMI has an EBV of 70 mL/kg. The patient with class III obesity has an EBV of 45 - 55 mL/kg. ``` For this reason, fluid management should be based on lean body weight (IBW x 1.3). To complicate matters further, these patients commonly have diastolic dysfunction, making volume overload and pulmonary edema more likely.

Answer 99

50 percent We all know that FRC decreases after induction of anesthesia. When a normal weight patient is in the supine position, FRC falls by 20 percent. When an obese patient is in the supine position, FRC can fall by as much as 50 percent! This contributes to a shorter time period between apnea and arterial desaturation. This situation is made even worse because the obese patient also has a higher oxygen consumption.

Answer 100

10 seconds Obstructive sleep apnea is defined as the cessation of airflow for at least 10 seconds (apnea), with 5 or more unsuccessful efforts to breathe (obstruction), and a drop of at least 4% SaO2 during sleep Hypopnea describes a smaller than normal minute ventilation and is associated with some amount of arterial saturation

Answer 101

Tidal volume 7 mL/kg total body weight Just because a patient's body habitus expands, does not mean that their lungs get bigger! For this reason, tidal volume is set at 6 - 8 mL/kg of ideal body weight (not total body weight). Anesthetic induction reduces FRC upwards of 50 percent! V/Q mismatch widens the A-a gradient and decreases SaO2. You may be tempted to use 100% FiO2, however this contributes to absorption atelectasis. Alveolar recruitment reverses atelectasis and reduces the need for a high FiO2. First we need to re-expand atelectatic alveoli with several vital capacity breaths (inhale to peak pressure of 40 cm H2O). And to keep these alveoli open, we apply PEEP 5 - 10 cmH2O. During induction, CPAP will prolong the time between apnea and desaturation. Permissive hypercapnia is acceptable, however this can increase pulmonary vascular resistance and right heart strain in the patient with pulmonary hypertension.

Answer 102

Ketorolac Since opioids induce ventilatory depression, we look for non-opioid adjutants to supplement a multimodal regimen. In the postop period, opioid sparing effects can be obtained from dexmedetomidine, clonidine, acetaminophen, and low dose ketamine Patients s/p gastric bypass should not receive ketorolac, since this drug increases the risk of GI bleeding in the postoperative period.

Answer 103

Total body water ``` Obesity is associated with an increased: Blood volume Cardiac output Renal clearance Vd lipid soluble drugs ``` Obesity is associated with a decreased: Total body water Pulmonary function Obesity is associated with altered: Plasma protein binding Liver function

Answer 104

Decreased blood viscosity The incidence of hypertension in the obese population is twice that of those of normal weight. Blood pressure can increase 6.5 mm/Hg for every 10 percent increase of body weight. The following contribute to the development of hypertension in the obese patient: Increased blood viscosity Hyperinsulinemia - Increases release of norepinephrine, cytokines, and angiotensinogen Elevated mineralocorticoid concentrations Abnormal sodium reabsorption

Answer 105

Roux-en-Y gastric bypass Gastric bypass confers the highest potential for weight reduction in morbidly obese patients. Additionally, it yields the best improvement in obesity related co-morbidities. Disadvantages include a longer hospital stay (2-3 days) as well as malabsorption related consequences including caloric deficiency, anemia, and deficiency of fat soluble vitamins (D, A, K, E). For this reason, there is a requirement of life-long nutritional support. Gastric bypass is associated with a 2 percent rate of anastomotic leak. The most common s/sx are unexplained tachycardia (72 percent), fever (63 percent), and abdominal pain (54 percent). Patients s/p gastric bypass should not receive ketorolac, since this drug increases the risk of postop GI bleeding in this patient population.

Answer 106

Roux-en-Y gastric bypass Biliopancreatic diversion Weight reduction surgery accomplishes its goal by: Restricting the amount of food that can be consumed at one time (gastric band or sleeve gastrectomy). Reducing the body's ability to absorb nutrients (jejunoileal bypass or biliopancreatic diversion). A combination of restriction and malabsorption (Roux-en-Y gastric bypass). Malabsorption is caused by reducing the size of the stomach and bypassing a portion of the small intestine. The more of the intestine that is bypassed, the greater the degree of malabsorption. Consequences of malabsorption include caloric malnutrition, anemia, and deficiency of fat-soluble vitamins (D, A, K, E). For this reason, there is a requirement of life-long nutritional support.

Answer 107

Increased risk of preterm labor Excessive blood loss during cesarean section Obesity increases the: Incidence of preterm labor Duration of the first and second stages of labor Need for cesarean section Risk of surgical complications (wound infection, blood loss, and venous thrombi/emboli) Difficulty in performing neuraxial blockade Difficulty of airway management Incidence of false negatives when searching for fetal abnormalities via ultrasound Incidence of macrosomia (large for gestational age)

Answer 108

Sitting Prone Gravity affects the distribution of blood volume, and the awake patient has a variety of compensatory mechanisms (SNS activation) to minimize the impact of body position changes. General anesthesia causes vasodilation, myocardial depression, and impairs baroreceptor responsiveness. Venous return is reduced as blood pools in dependent regions in the body. Taken together, these changes, render the patient more susceptible to hemodynamic instability when placed in certain surgical positions. For each position, think about where the lower extremities are relative to the heart. In the sitting, flexed lateral, and prone positions, the lower extremities are below the level of the heart. This explains why these positions are associated with a higher incidence of hemodynamic changes (decreased BP and CO).

Answer 109

Trendelenburg Flexion of the neck You have diagnosed an endobronchial intubation. Compared to the left mainstem bronchus, the right mainstem bronchus takes off at a less acute angle. This explains why the endotracheal tube is more likely to slip down the right side. There are two conditions that increase the risk of this complication. 1. Neck flexion - the tube goes where the nose goes. Neck flexion makes the endotracheal tube advance. This increases the risk of endobronchial intubation. Neck extension moves the endotracheal tube towards the vocal cords. This increases the risk of inadvertent extubation. 2. The position of the carina in the chest. In the Trendelenburg position, the abdominal contents shift cephalad, moving the diaphragm and thoracic contents towards the endotracheal tube. Remember that the tube is secured in a fixed location at the mouth, so the tip of the tube isn't going to change.

Answer 110

Bezold-Jarish The Bezold-Jarisch reflex can be seen in patients with an interscalene block in the sitting position (think shoulder surgery). The BJR causes the triad of: profound hypotension, bradycardia, and coronary vasodilation. In the setting of inadequate preload, the heart slows to allow it adequate time to fill. This is the same reflex that's been implicated in unexplained cardiac arrest during spinal anesthesia.

Answer 111

Sitting position A "mill wheel" murmur may signal the presence of a venous air embolism. VAE can occur anytime there is a pressure gradient between the right atrium and the veins at the operative site. This gradient is largest in the sitting position. If you encounter a question like this and you don't see the sitting position as an answer choice, the best approach is to consider which answer choice creates the largest pressure gradient between the veins at the operative site and the right atrium. Paradoxical air embolism can occur when the patient has a patent foramen ovale (PFO). TEE is the gold standard for diagnosing a PFO.

Answer 112

Improve venous return Reduce surgical blood loss When you place the patient in the prone position, your primary objective is to minimize pressure on the abdomen and the vena cava. This confers several key benefits: Improved pulmonary mechanics Improved venous return Decreased venous pressure The intervertebral veins do not contain valves. Increased venous pressure is transmitted to this region and can contribute to increased surgical blood loss. When compared to the Wilson frame and chest rolls, the Jackson table is least likely to negatively impact pulmonary mechanics (compliance is better and PIP is lower).

Answer 113

Axillary roll placed caudal to the axilla The brachial plexus is susceptible to stretch and compression injuries. In the supine position, arm ABduction > 90 degrees stretches the brachial plexus around the head of the humerus. Lateral neck rotation stretches the brachial plexus on the contralateral side. In the Trendelenburg position shoulder braces are used to prevent the patient from sliding on the OR table. The best answer is to never use shoulder braces! If they are used, they should be placed at distal end of the clavicle. Improper placement near the base of the neck or midway along the clavicle increases the risk of a compression injury. In the prone position, the shoulders should not be allowed to sag forward and the arms should not be extended over the head. In the lateral decubitus position, brachial plexus injury is most likely the result of excessive stretching, extension, or external rotation of the arm or posterior displacement of the shoulder. An axillary roll is placed distal to the axilla. A roll placed inside the axilla can cause neurovascular compression.

Answer 114

Male gender Cardiac surgery Extremes of body habitus Prolonged hospital stay These risk factors are associated with a higher risk of perioperative nerve injury: Male gender > female gender (particularly if over 50 years of age) Cardiac surgery (median sternotomy and sternal retraction) Prolonged hospital stay Extremes of body habitus Undiagnosed preexisting ulnar neuropathy

Answer 115

Forearm supination Forearm positioning has been implicated as a source of ulnar nerve injury. In the supine patient: Forearm supination (palms up) is best when the arms are abducted. The neutral position (palms in) is best when the arms are tucked at the patient's sides. It's also an acceptable alternative when the arms are abducted. Forearm pronation (palms down) is avoided, as it is associated with a higher risk of ulnar injury. Extreme elbow flexion can also contribute to ulnar neuropathy. Unfortunately, ulnar nerve injury often occurs with no perceivable cause. It may not be preventable despite your best efforts.

Answer 116

Hyperextension of elbow Hyperextension of the elbow can stretch the median n. Extreme flexion of the elbow can stretch the ulnar n. The ulnar n. is also affected by forearm position. If the patient is supine: Forearm supination is best when the arms are abducted. The neutral position is best when the arms are tucked at the patient's sides. It's also an acceptable alternative when the arms are abducted. Forearm pronation is avoided, as it is associated with a higher risk of ulnar injury.

Answer 117

Radial + Wrist drop Ulnar + Claw hand Median + Inability to oppose thumb Radial n. injury presents with wrist drop. This can be caused by external compression of the lower third of the arm (spiral groove at the humerus). Ulnar n. injury presents with the inability to abduct the pinky finger. Permanent injury can cause the intrinsic muscles in the hand to atrophy, which presents as "claw hand." Median n. injury presents with the inability to oppose the thumb. The most common cause is IV insertion at the antecubital site.

Answer 118

Long Thoracic nerve The long thoracic nerve: Arises from C5-C7. Innervates the serratus anterior muscle. Long thoracic nerve injury presents with scapular winging (dorsal protrusion of the scapula).

Answer 119

Obturator + Impaired leg adduction Femoral + Impaired knee extension Peroneal + Foot drop Obturator n. injury: Most common causes: excessive traction during lower abdominal surgery, forceps delivery, and/or excessive flexion of the thigh towards the groin. Presentation: inability to ADDuct the leg and reduced sensation over the medial aspect of the thigh. Femoral n. injury: Most common cause: excessive traction during lower abdominal surgery. Presentation: impaired knee extension, impaired hip flexion, and reduced sensation over the anterior thigh and anteromedial aspect of the leg (remember the femoral n. gives rise to the saphenous n.). Peroneal n. injury Most common cause: external compression (head of fibula compressed against a "candy cane" stirrup). Presentation: foot drop, inability to evert the foot, and inability to extend the toes dorsally.

Answer 120

Orthopedic fracture table The pudendal nerve can be injured by compression against a perineal post on an orthopedic table. The Wilson frame and Jackson table are used during spinal surgery. The horseshoe head rest stabilizes the face in the prone position. The face is pretty far from the pudendal nerve.

Answer 121

Both legs must be moved simultaneously to prevent hip dislocation Extreme hip flexion can injure the sciatic nerve The lithotomy position can cause hip dislocation, spinal torsion, and back pain. Both legs should be raised and lowered together to avoid injury. The sciatic nerve can be injured by extreme hip flexion, external rotation of the legs, and extended knees. The common peroneal nerve can be damaged when the LATERAL aspect of the leg leans against the stirrup bar (the peroneal nerve wraps around the fibular head). The saphenous nerve can be damaged when the MEDIAL aspect of the leg leans against the supporting cradle (the saphenous nerve resides near the tibia).

Answer 122

The sural nerve of the superior leg The superficial peroneal nerve of the dependent leg Many patients have the tendency to cross their legs prior to anesthetic induction, and failing to uncross the legs can contribute to peripheral nerve injury. The sural n. is injured in the top leg: Pressure from the superior aspect of the dependent leg will damage the sural nerve on the underside of the superior leg. The superficial peroneal n. is injured in the bottom leg: Pressure from the underside of the superior leg will damage the superficial peroneal nerve of the dependent leg.

Answer 123

Corneal abrasion Corneal abrasion is the most common cause of perioperative eye injury. It is usually caused by direct trauma or drying of the cornea. Movement during eye surgery is the single most common cause of corneal abrasion. Ischemic optic neuropathy is the most common cause of postoperative vision loss. Central retinal artery occlusion is usually the result of direct pressure on the globe.

Answer 124

Glycine toxicity Intraocular perfusion pressure = MAP - Intraocular pressure Ischemic optic neuropathy (ION) is the result of hypoperfusion and ischemia of the optic nerve. As you can predict from the equation, the most common causes of ION are impaired perfusion and increased intraocular pressure. Patient risk factors: male gender, obesity, diabetes, hypertension, and vascular comorbidities. Intraoperative risk factors: prone position, spine surgery, extensive surgical times, large blood loss, and hypotension (SBP < 100 mmHg). In patients with L-arginine deficiency, glycine toxicity tends to increase blood ammonia. This can temporarily impair vision until the blood ammonia level returns to normal.

Answer 125

National practice standards The AANA Practice Standards are the highest standards that must be followed by all CRNAs. Practice standards are RULES that define the minimum expected actions and behaviors for providing professional services. Practice guidelines are just that: guidance, but not rules. Position statements reflect currently accepted beliefs on various issues, usually formulated by a committee of recognized experts. Local standards of care—which are often used to defend untoward clinical actions—may be the lowest bar one could set for a clinical practice and are generally not considered to provide an effective legal defense.

Answer 126

Low incidence with high morbidity Significant effects on the fetus In the parturient, you must disclose any risk with a/an: High incidence High morbidity Association with adverse fetal effects Clearly, this means you should be able to delineate these specific risks to the patient.

Answer 127

Battery Intentional tort Battery (as well as assault) are intentional torts; in this case, battery occurred when the patient was touched without consent during placement of the epidural. This unlawful act does not meet the definition of negligence since no damages occurred. The concept of res ipsa loquitur depends upon the presence of a negligent act.

Answer 128

Accepting responsibility while concealing a medication error Concealment or suppression of facts that are relevant to a patient’s responses or outcomes is evidence of a dysfunctional safety environment.

Answer 129

Decreases the risk of making drug dose errors The stress of a critical incident decreases cognitive function and impairs memory. The use of a cognitive aid provides a quick and easy reference for differential diagnosis, a reminder of best practices, and verification of proper drug doses. The use of a cognitive aid is often a task that is delegated to one of the team members, and this person relays this information to the rest of the team.

Answer 130

Workplace hostility Anxiety and depression Both night-shifts and double shifts contribute to extreme fatigue and chronic stress, primarily when worked on a regular basis. This can lead to a variety of psychological effects including anxiety, depression, and hostility, and may increase the risk of medical error. When fatigued, situational awareness erodes, and the ability to self-assess readiness for work falls.

Answer 131

115 dB In general, for accurate hearing and interpretation of audible signals in the OR, audible monitoring must be set at least 20 dB above the background noise. In this case, the required 115 dB is also the OSHA peak allowable exposure to noise in a work setting! Noise pollution is particularly damaging to work efficiency, short-term memory, and the ability to perform psychomotor tasks. All of these issues come into play during induction and emergence, which is precisely when excessive (and typically unnecessary) OR noise is common.

Answer 132

Workplace production pressure Uncontrolled access to addictive drugs Even the most psychologically stable anesthesia provider faces a risk for abusing substances due to easy access to highly addictive drugs (propofol, opioids) and the stress of a highly demanding profession in a financially driven employment sector. As an aside, the only physical factor associated with substance abuse is the presence of acute or chronic pain.

Answer 133

A minimum of one year in recovery Five years of monitoring with random drug testing Current recommendations for re-entry to practice include abstinence-based recovery for at least one year AND at least five years of monitoring with random drug testing. These relatively long periods of guided treatment and monitoring are due to the high relapse rate and easy diversion of drugs in a typical anesthesia practice.

Answer 134

Inadequate ventilation Here's the most common causes of respiratory M&M within the subset of claims for adverse respiratory events, Inadequate ventilation = 38% Esophageal intubation (unrecognized) = 18% Difficult intubation = 17% Inadequate FiO2 = 11% Inadequate ventilation includes hypoxia, hypercarbia, or both.

Answer 135

Cervical spine injection The increase in chronic pain procedures has brought about an increase in pain management related claims. Of these, cervical spine injections are associated with the highest frequency of claims, where more than 50 percent of cases resulted in permanent spine injury! Other chronic pain claims include: Medications 17 percent (death is the most common outcome) Lumbar injections 17 percent Implanted devices 16 percent

Answer 136

Contact your insurance carrier In the event you’re served with a lawsuit, there are several things that you should do to best protect yourself. Here’s a list of the initial actions: Notify your insurance carrier IMMEDIATELY Do NOT discuss the case—not even with other providers who were involved Do NOT alter any records Gather all records of the case (EHR, case notes, critical incident reports, billings, any correspondence about the case) Make notes regarding all aspects of the case (if you wrote a detailed case note/incident report immediately after the event as recommended, you will have much of this already) Cooperate with your insurer’s attorney After this, the first thing you'll need to do is work with your attorney to write an initial response to the summons.