test 3 flippled classroom Flashcards
Which evoked potential is most resistant to anesthetic suppression?
C) Brainstem Auditory Evoked Potentials (BAEPs)
BAEPs originate in the brainstem, which is more resistant to anesthetic suppression than cortical pathways.
Which of the following best describes evoked potentials?
B) Electrical responses recorded from the nervous system after a stimulus
Evoked potentials (EPs) measure the nervous system’s response to external stimuli, such as electrical, auditory, or visual inputs.
During neurosurgical procedures, a sudden loss of Somatosensory Evoked Potentials (SSEPs) may indicate:
B) Ischemic injury to the spinal cord or brain
A sudden loss or significant decrease in SSEP amplitude suggests reduced blood flow or neural damage.
Which type of evoked potential evaluates the integrity of the sensory pathways from the periphery to the brain?
C) Somatosensory Evoked Potentials (SSEPs)
SSEPs evaluate the function of the sensory pathways by stimulating peripheral nerves and recording the response at the brain and spinal cord.
Which anesthetic management strategy is preferred when using Motor Evoked Potentials (MEPs)?
B) Total intravenous anesthesia (TIVA) with minimal neuromuscular blockade
MEPs require intact motor pathways, so neuromuscular blockade should be minimized.
What is the primary reason Visual Evoked Potentials (VEPs) are not commonly used to assess depth of anesthesia?
B) They are highly sensitive to anesthetics and easily suppressed
VEPs are extremely sensitive to anesthetics, making them unreliable for routine intraoperative monitoring.
Which patients are not ideal to use the BIS monitor on as readings may not be reliable or fully accurate?
A) Infants and children < 18 years old, B) Patients receiving Ketamine as the induction agent, C) Patients > 60 years old, E) Patients receiving Nitrous Oxide with other inhalation agents
These groups have age-related EEG waveform differences or altered waveforms that can skew the BIS monitor’s readings.
What is the primary purpose of BIS monitoring?
B) To assess the depth of anesthesia using EEG signals
BIS monitoring provides near real-time data on patient consciousness levels.
What BIS range is recommended for general anesthesia?
C) 40-65
A BIS value between 40 and 65 reduces the risk of awareness.
Why is BIS monitoring not always reliable?
C) Some patients report awareness despite BIS values below 65
EEG responsiveness varies among individuals, affecting BIS accuracy.
Which EEG components are analyzed by BIS monitoring?
A) Low-frequency waves and high-frequency beta waves
These components help determine if a patient is in deep anesthesia or light sedation.
What is a recommended best practice for preventing intraoperative awareness?
B) Using multimodal monitoring with BIS and ETAC
Combining different monitoring methods improves anesthesia depth assessment and minimizes the risk of awareness.
What type of anesthetic gas analyzer can measure oxygen?
A) Paramagnetic oxygen analyzer, C) Galvanic cell oxygen analyzer
Oxygen is a paramagnetic substance that reacts to magnetic fields, measurable by paramagnetic analyzers.
What does MAC 1.0 mean?
The minimum alveolar concentration needed to inhibit movement in 50% of patients in response to noxious stimuli.
MAC is a standard measure of anesthetic potency.
What does MAC-BAR represent?
The minimum alveolar concentration necessary to blunt adrenal response to noxious stimuli.
MAC-BAR refers to anesthetic gas concentration needed to inhibit pain in patients.
Why does a galvanic oxygen analyzer need to be replaced every so often?
The anode (lead) is eventually consumed by the continued chemical reaction.
The reaction consumes the anode and eventually needs replacement.
How does a gas analyzer detect multiple gases simultaneously?
It uses multiple wavelengths of inferred light to determine the concentration of each gas by measuring the absorption of each wavelength.
Each gas absorbs a unique wavelength of inferred light.
Which conditions are associated with increased SvO₂ values?
A) Sepsis, B) Cyanide toxicity, E) Left-to-right shunt
Increased SvO₂ can occur due to conditions that either increase oxygen delivery or impair oxygen utilization.
Which statement about central venous oxygen saturation (ScvO₂) is true?
A) ScvO₂ is measured at the junction of the superior vena cava and right atrium
ScvO₂ primarily represents upper body and head venous return.
A patient presents with respiratory acidosis. Which ABG findings would be most consistent with uncompensated respiratory acidosis?
A) pH 7.28, PaCO₂ 55 mmHg, HCO₃⁻ 24 mEq/L
Uncompensated respiratory acidosis is characterized by a low pH and elevated PaCO₂.
Which formula correctly calculates bicarbonate replacement in metabolic acidosis?
B) (Normal HCO₃⁻ - Patient’s HCO₃⁻) × Weight (kg) × 0.3
0.3 represents the volume of distribution for bicarbonate in extracellular fluid.
Which mechanisms contribute to increased CO₂ production in the perioperative setting?
A) Fever, B) Malignant hyperthermia, C) Tourniquet release, E) Thyroid storm
These conditions elevate metabolic rates, leading to increased CO₂ generation.
What are the conditions that contribute to increased CO₂ production?
Fever, thyroid storm, malignant hyperthermia, tourniquet release
Increased metabolic rate leads to greater oxygen consumption and carbon dioxide generation.
How does hyperthermia and hypercapnia affect the oxyhemoglobin dissociation curve?
Right shift
This indicates reduced affinity of hemoglobin for oxygen, enhancing oxygen unloading at tissues.
What is the primary determinant of cerebral perfusion pressure (CPP)?
The difference between MAP and ICP
CPP = MAP - ICP (or CVP, if greater than ICP).
Which anesthetic agent is preferred for neuroanesthesia due to its effects on ICP, CBF, and CMRO₂?
Propofol
Propofol reduces cerebral blood flow and metabolic rate of oxygen significantly.
What is a contraindication for the use of succinylcholine in neurosurgical patients?
Severe traumatic brain injury (TBI)
Succinylcholine can cause life-threatening hyperkalemia in these patients.
Which intravenous anesthetic agent is known to cause adrenal suppression?
Etomidate
Etomidate is avoided in patients with TBI and sepsis due to the risk of prolonged adrenal insufficiency.
What do plateau waves (A waves of Lundberg) indicate in intracranial pressure monitoring?
Persistent ICP elevation (40-100 mmHg) lasting 5-20 minutes
These indicate critically low intracranial compliance.
What ventilatory strategy optimally balances ICP reduction while avoiding cerebral ischemia?
Tight PaCO₂ control (30–35 mmHg)
This induces mild vasoconstriction and reduces cerebral blood volume while preserving perfusion.
Which modality is used to monitor brain oxygenation?
Cerebral oximetry
This monitors adequacy of oxygenation specific to the brain.
What technology does the cerebral oximeter use?
Near-infrared spectroscopy
NIRS is used for monitoring brain oxygenation levels.
How does a cerebral oximeter function in monitoring brain oxygenation?
By measuring light attenuation from an emitting light source
Emitter/sensor pads are applied to the forehead.
What is the primary goal of cerebral oximetry monitoring?
To ensure NIRS values remain at least 75% of the baseline reading
This helps avoid cerebral desaturation.
In which clinical scenarios is cerebral oximetry most frequently used? (Select 3)
Neonatology, Cardiac surgery, Carotid endarterectomy
These are the most common applications of NIRS.
What conditions can decrease the accuracy of Near-Infrared Spectroscopy (NIRS)? (Select 5)
Changes in blood pressure, Partial pressure of carbon dioxide in arterial blood (PaCO₂), Regional blood volume variations, Hemoglobin concentration differences, Individual variability
These factors can affect NIRS readings.
