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Apex Miscellaneous Exam Questions 2024 /2025 | Actual Questions and
Answers Latest Updated 2024/2025 (Graded A+)
Describe the architecture of an atom - ✔✔The atom is the basic building block that makes up all matter
- Protons (+) charge
- Neutrons (neutral) charge
- Electrons (-) charge Protons and neutrons are in the center of the atom (nucleus), electrons orbit the nucleus in the electron cloud How do you know if an atom carries a charge? What is a charged atom called? - ✔✔An atom will have a neutral charge if electrons = protons A positive charge if protons > electrons A negative charge if electrons > protons An ion is an atom that carries a positive or negative charge. An ion with a positive charge is called a cation An ion with a negative charge is called an anion What is an ionic bond? - ✔✔An ionic bond involves the complete transfer of valence electrons from one atom to another. This leaves one atom with a negative charge and the other with a positive charge. Metals tend to form ionic bonds.
Ionic bonds are common with metals as well as acids and bases. What is a covalent bond? - ✔✔Involves the equal sharing of electrons. This is the strongest type of bond. What is a polar covalent bond? - ✔✔an "in-between" type of bond Atoms share electrons, but the electrons tend to remain closer to one atom than the other. This creates a polar molecule where one area of the molecule is relatively positive and the other is relatively negative. What are Van der Waals forces? - ✔✔Describe a very weak intermolecular force that holds molecules of the same type together. Electrons orbiting a molecule are in constant motion. This creates a temporary partial + and - charge 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. This is the weakest type of molecular attraction. Define Dalton's law. List several examples of how it can be used in the OR. - ✔✔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. Ways to apply Dalton's law:
- Calculate the partial pressure of an unmeasured gas
- Calculate the total pressure
- Convert partial pressure to volumes %
- Convert volume % to partial pressure
- A patient with COPD has a reduced alveolar surface area, and therefore has a slower rate of inhalation induction
- Calculation of CO
- Drug transfer across the placenta Boyles, Charles, Gay-Lussac - ✔✔Boyle's law has an inverse relationship. As one variable gets larger, the other gets smaller, and vice versa. Charles's and Gay-Lussac's law have direct relationships. As one variable gets larger, the other gets larger, and vice versa. List examples of how Boyle's law can be applied in the OR - ✔✔Boyle's law = P x V Diaphragm contraction increases tidal volume Pneumatic bellows Squeezing an ambu bag Using the bourdon pressure gauge to calculate how much O2 is left in an O2 tank List several examples of how Charles's law can be applied in the OR - ✔✔Charles law = V/T LMA cuff ruptures when placed in an autoclave List several examples of how Gay-Lussac's law can be applied in the OR - ✔✔Gay-Lussac's law = P/T Oxygen tank that explodes in a heated environment
What is the function of the ideal gas law? - ✔✔The ideal gas law unifies all 3 gas laws into a single equation
- PV = nrT
- n = number of moles
- r = constant 0.0821 liter-atm/K/mole Define Ohm's law - ✔✔-Current passing through a conductor is directly proportional to the voltage and inversely proportional to the resistance. We can adapt Ohm's law to understand fluid flow How is Poiseuille's law related to Ohm's law? - ✔✔-Poiseuille's law is a modification of Ohm's law that incorporates vessel diameter, viscosity, and tube length
- Blood flow = πR^4ΔP/8nl
- R = radius
- P = arteriovenous pressure gradient n = viscosità
- l = length How do changes in radius affect laminar flow (x2, x3, x4, x5) - ✔✔R = 1^4 = 1 R = 2^4 = 16 R = 3^4 = 81 R = 4^4 = 256
If the fluid's velocity is high, then the pressure exerted on the walls of the tube will be low. If the fluid's velocity is low, then the pressure exerted on the walls of the tube will be high. Example: Think of a river. When the river is wide, the water moves slowly. When it becomes narrow, the water moves faster. This is because the same volume of water is moving through the wide and narrow parts of the river at any given time. While the water is moving slowly, the pressure exerted on the riverbank is higher. When the river narrows, the velocity of the water increases, so it exerts less pressure on the riverbank. Explain the Venturi effect, and give some examples. - ✔✔The Venturi effect is an application of the Bernoulli principal. As air flow in a tube moves past the point of constriction, the pressure at the constriction decreases (Bernoulli) and if the pressure inside the tube falls below atmospheric pressure, then air is entrained into the tube. (Venturi) Adjusting the diameter of the constriction allows for control of the pressure drop and the amount of air that is sucked into the tube. The key is air entrainment. Ex: Jet ventilator, Venturi, nebulizer Explain the Coanda effect and give some examples. - ✔✔The Coanda effect describes how a jet flow attaches itself to a nearby surface and continues to flow along that surface, even when the surface curves away from the initial jet direction Ex: Wall hugging jet of mitral regurgitation or water that follows the curve of a glass Law of LaPlace for a sphere and for a cylinder - ✔✔In spheres and cylinders, the law of Laplace illustrates the relationship between the wall tension, internal pressure, and radius. Pressure is a pushing force. It pushes the walls of the object apart. Tension is a pulling force. It holds the walls of the object together.
In a sphere, Tension = (P x R)/ 2 Ex: alveolus, cardiac ventricle, saccular aneurysm In a cylinder, Tension = P x R Ex: blood vessels, aortic aneurysm What is the yearly maximum for radiation exposure? How does this change if someone is pregnant? - ✔✔Non-pregnant- yearly maximum radiation is 5 rem. The eye and thyroid are most susceptible to injury. Pregnant person- yearly max for the fetus is 0.5 rem or 0.05 rem/month. The fetus is most susceptible to injury. List 3 ways to protect yourself from radiation exposure. - ✔✔3 ways to limit exposure are: time, distance and shielding How can we apply the inverse square law to radiation exposure? - ✔✔Distance is an easy way to protect yourself from ionizing radiation. The minimum safe distance from the radiation source is 6 feet. Radiation obeys the inverse square law. It states that the amount of exposure is inversely proportional to the square of the distance from the source. Intensity = 1/Distance ^ What is boiling point, and how is it affected by atmospheric pressure? - ✔✔Boiling point is the temperature at which a liquid's vapor pressure equals atmospheric pressure. Increased atmospheric pressure = increased boiling point (hyperbaric O2 chamber) Decreased atmospheric pressure = decreased boiling point (high altitude)
This explains why an oxygen cylinder that is opened quickly feels cool to the touch. Conversely, rapid compression of a gas intensifies its kinetic energy, causing the temperature to rise. Remember- Joule is cool What is an 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. What is critical temperature, and how does this apply to gas cylinders? - ✔✔The highest temperature where a gas can exist as a liquid. AKA the temperature above which a gas cannot be liquefied, regardless of how much pressure is applied to it. The critical temperature for nitrous oxide is 36.5, which explains why it primarily exists as a liquid inside the cylinder. Of all the gases used in the OR, only N2O and CO2 have critical temperatures below room temperature. What is critical pressure? - ✔✔The minimum pressure required to convert a gas to a liquid at its critical temperature Temperature conversion from K to C and vice versa - ✔✔Celsius = K - 273. K = C + 273. Temperature conversion from F to C and back - ✔✔C = (F-32) x 5/ F = (C x 1.8) + 32
Define pressure - ✔✔Pressure = Force / Area Increase area = decrease pressure Decrease area = increase pressure Pressure conversion factors - ✔✔1 atm = 760 mmHg = 760 torr = 1 bar = 100 kPa = 1033 cm H2O = 14. psi 1 mmHg = how much cm H2O? - ✔✔1. 1 cmH2O = how much mmHg? - ✔✔0. What is Avogadro's number? - ✔✔Says that 1 mole of any gas is made up of 6.023 x 10^23 atoms A mole of a gas is equal to the molecular weight of that gas in grams If a molecule is diatomic (O2) must account for both atoms What are the 4 mechanisms of heat transfer? - ✔✔Radiation- infrared, about 60% of all heat loss Convection - air = 15-30% Evaporation - water loss = ~20% Conduction - contact = <5%
Decreased if placed in proximal esophagus due to cool inspiratory gas Sites of temperature measurement - ✔✔ What are the 3 ingredients required to produce a fire? Give examples of each. - ✔✔Fuel: ETT, drapes, surgical supply Oxidizer: O2, N2O Ignition: electrosurgical cautery, laser Steps to take during an airway fire - ✔✔Do NOT squeeze the reservoir bag as you extubate the patient. This can create a blow torch effect at the distal end of the ETT and/or push debris into the lower airway. What does "laser" stand for? How is it different from ordinary light? - ✔✔Light Amplification by Stimulated Emission of Radiation. Laser light differs from ordinary light because it is: Monochromatic Coherent Collimated What is the difference between a long and short wavelength laser? What are the clinical consequences of this? - ✔✔Long wavelength lasers absorb more water and do NOT penetrate deeply into tissue. The cornea is at risk with long wavelength lasers. Short wavelength lasers absorb less water and penetrate deeper into tissue. The retina is at risk with short wavelength lasers.
What color goggles must be worn for each type of laser: CO2, Nd:YAG, Ruby, Argon - ✔✔Co2 = Clear Ruby = Red Argon = Amber Nd:YaG = Green Discuss the flammability of endotracheal tubes in the context of laser surgery on the airway. - ✔✔Most ETT are flammable Laser reflective tape is no longer advised. It is smarter to use a laser resistant ETT. Laser resistant does not mean laser proof! The cuff is the most vulnerable component of the ETT. Laser resistant tubes do not have laser resistant cuffs. Fill the cuff with saline. This helps absorb the thermal energy produced by the laser. Many laser resistant ETTs have 2 cuffs. The proximal cuff is filled with saline or dye. If it becomes perforated by the laser, then the distal cuff will hlpefully remain intact and permit continued PPV. Laser resistant ETTs do not reduce the risk of fire when electrosurgical cautery is used. 4 degrees of burns. Which require a skin graft? - ✔✔1st degree- epidermis, spontaneous healing 2nd degree- superficial- upper portion of dermis- spontaneous healing 2nd degree-deep = through dermis, skin graft required
Describe the Modified Brooke formula for resuscitation in burn patients - ✔✔Basically the same as the Parkland, only with the First 24 hours- 2 ml/kg/TBSA instead of 4 What is an acceptable UOP in a burn patient? Is this different in patients who have suffered a high voltage electrical injury? - ✔✔Adult > 0.5ml/kg/hr Child >1ml/kg/hr High voltage electrical injury > 1-1.5ml/kg/hr Why is the burn patient at risk for abdominal compartment syndrome? What is the diagnosis and treatment of this complication? - ✔✔May result from aggressive fluid resuscitation Intra-abdominal HTN is defined as IAP > 20 mmH2O or >12 mmHg and evidence of organ dysfunction (hemodynamic instability, oliguria, increased PIP) Tx: NMB, sedation, diuresis, decompression via laparotomy Discuss the clinical considerations for the patient with CO poisoning - ✔✔CO binds to Hgb with an affinity 200x O CO shifts oxyHgb curve to left Oxidative phosphorylation is impaired
Inadequate O2 delivery and utilization causes metabolic acidosis Blood is cherry red Pulse ox not accurate, may be falsely elevated Treatment = 100% FiO2 or hyperbaric oxygen Discuss the use of NMB in burn patients - ✔✔Up-regulation of extrajunctional receptors begins after 24 hours. Succs is safe within the first 24 hours, but not after 24 hours. The dose of NDNMB should be increased 2-3x because there are more receptors. Describe the physiologic changes that accompany electroconvulsive therapy - ✔✔Initial response: Increased PNS activity during tonic phase (~ 15 seconds) Secondary response: Increased SNS activity during the clonic phase (several minutes) Absolute and relative contraindications to ECT - ✔✔Typically related to an increased SNS response or increased ICP Most common causes of death are MI and cardiac dysrhythmias. Patients with co-existing CV disease may undergo ECT if the hemodynamics are well managed. Compare neuroleptic malignant syndrome with malignant hyperthermia - ✔✔NMS is caused by dopamine depletion in the basal ganglia and hypothalamus Causes: dopamine antagonists or withdrawal from dopamine agonists.
Closed angle glaucoma is caused by a closure of the anterior chamber. This creates a mechanical outflow obstruction. Which drugs reduce aqueous humor production?
- Which increase aqueous humor drainage? - ✔✔Rx that decrease: Acetazolamide and timolol Rx that increase drainage: Echothiophate What is strabismus correction? What unique considerations apply to the anesthetic management of these patients? - ✔✔Corrects the misalignment of extraocular muscles and re-establishes the visual axis. 3 key considerations Increased risk of MH Increased risk of PONV Increased risk of oculocardiac reflex Which patient populations benefit from a TAP block? - ✔✔The TAP block is a unilateral, PNB that targets the nerves of the anterior and lateral abdominal wall. Best for abdominal procedures (general, GYN, urologic) that involve T9-L Bilateral TAP blocks are required for midline incision or laparoscopic surgery Anatomy and landmarks required for a TAP block - ✔✔SubQ - external oblique muscle- internal oblique muscle- Transverse abdominis muscle- peritoneum Landmarks form triangle of Petit External oblique muscle Latissimus dorsi muscle
Iliac crest Define allodynia and give an example. - ✔✔Pain due to a stimulus that does not normally produce pain
- Ex: Fibromyalgia Define dyesthesia and give an example - ✔✔Abnormal and unpleasant sense of touch Ex: burning sensation from diabetic neuropathy Define neuralgia and give an example - ✔✔Pain localized to a dermatome
- Ex: Herpes zoster (shingles) What is the defining characteristic between type 1 and type 2 complex regional pain syndrome? - ✔✔Type 1 = reflex sympathetic dystrophy Type 2 = causalgia Type 2 is always preceded by a nerve injury Discuss the use of a thoracic paravertebral block. - ✔✔-LA is injected into the paravertebral space and targets the ventral rams of the spinal nerve as it exits the vertebral foramen
- Think of it like a single shot, unilateral epidural
- Provides analgesia for breast surgery, thoracotomy, and rib fracture
