Flipped Classroom 2nd Flashcards
What is the purpose of the sample port in gas analyzers?
Allows for inhaled and exhaled gas concentrations
This enables monitoring the minimum alveolar concentration (MAC), which indirectly measures the amount of volatile anesthetic delivered to the brain.
What does the difference in gas concentrations indicate?
Identifies how much gas is being diffused into arterial blood and out of venous blood.
What is Minimum Alveolar Concentration (MAC)?
The minimum alveolar concentration necessary to immobilize 50% of patients exposed to noxious stimuli.
Which anesthetic gas requires a MAC of 1.0?
MAC = 1.0
What are the types of anesthetic gas analyzer machines?
- Ramen Scattering Analysis (infrared based)
- Mass Spectrometry
- Piezoelectric analyzer
- Photoacoustic analyzer (infrared based)
Why is Mass Spectrometry not commonly used?
Not cost-efficient, large, not very portable, and no longer used.
What is a limitation of the Piezoelectric analyzer?
Unable to identify the gas being measured.
What is the advantage of the Photoacoustic analyzer?
Very portable and accurate but cannot measure oxygen.
How do anesthetic gas analyzers measure multiple gases?
Using infrared light based on Beer–Lambert law.
What does Beer’s law relate to in gas analysis?
The amount of infrared light being absorbed by a specific gas to calculate its concentration.
Why is a separate analyzer used for oxygen?
Oxygen does not absorb infrared light.
What does a Galvanic Oxygen Analyzer contain?
- Lead anode
- Gold cathode
- Electrolyte solution
- Semipermeable membrane for oxygen
What is the reaction that occurs in a Galvanic Oxygen Analyzer?
2 Pb2+ + 4 OH- -> 2 PbO + 2 H2O + 4 e-
What drives the amount of oxygen that crosses the membrane in a Galvanic Oxygen Analyzer?
The partial pressure of oxygen.
What is the principle of the Paramagnetic Oxygen Analyzer?
Oxygen is attracted by magnetic fields.
What happens to oxygen molecules in a Paramagnetic Oxygen Analyzer?
They are attracted to the center of the magnetic field, moving a mirror that reflects light into a sensor.
What is the normal range of pH in arterial blood gas analysis?
7.35–7.45.
What does PaO2 measure in ABG?
Oxygen dissolved in the plasma.
What is the normal range for PaO2?
80–100 mmHg.
What does PaCO2 reflect?
Respiratory function and ventilation.
What is the normal range for PaCO2?
35–45 mmHg.
What does HCO3- represent?
A key component of the body’s buffer system that regulates pH.
What is the normal range for HCO3-?
22–26 mEq/L.
What is Base Excess (BE)?
Indicates the amount of excess or deficit in base to maintain a normal pH.
What is the normal range for Base Excess (BE)?
-2 to +2 mEq/L.
What does SaO2 measure?
The percentage of hemoglobin that is bound to oxygen directly in arterial blood.
What is the normal range for SaO2?
95–100%.
What does lactate indicate?
Anaerobic metabolism and tissue hypoxia.
What is the normal range for lactate?
0.5–1.6 mmol/L.
How is oxygen transported in blood?
- Dissolved in plasma (1.5%)
- Bound to hemoglobin
What is the formula for oxygen content (CaO2)?
CaO2 = (SaO2 x 1.39 x Hb) + (0.003 x PaO2)
What does a high FiO2 level indicate?
Increased dissolved oxygen in plasma.
What is the significance of the Alveolar Gas Equation?
PaO2 depends on FiO2 and the partial pressure of carbon dioxide.
What is the formula for CaO2?
CaO2 = (SaO2 x 1.39 x Hb) + (0.003 x PaO2)
What is the normal P/F ratio?
> 400 mm Hg
What is the definition of hypoxemia?
PaO2 < 60 mmHg, low oxygen in blood (pulmonary issue)
What factors influence the Alveolar Gas Equation?
- FiO2
- Barometric pressure
- Ventilation
What can cause faster desaturation in obese patients?
Lower FRC
What is the effect of preoxygenation on hypoxemia time?
Extends time before hypoxemia (~7 min vs. 30 sec on room air)
What does a right shift in the oxyhemoglobin dissociation curve indicate?
Decreased affinity for oxygen, better unloading
What are the causes of hypoxemia?
- Low barometric pressure
- Apnea
- Equipment failure
What does the Bohr effect describe?
Increased PCO2 and H+ ions enhance O2 unloading in tissues
What is the difference between hypoxia and hypoxemia?
Hypoxia: Low oxygen in tissues; Hypoxemia: Low oxygen in blood
What is the primary method of CO2 transport in blood?
- Dissolved in plasma (5-10%)
- Bound to hemoglobin (5-10%)
- Bicarbonate (80-90%)
What is the normal range for arterial blood pH?
7.35 - 7.45
What happens during respiratory acidosis?
Elevation in PaCO2 reduces arterial pH
What is the definition of metabolic acidosis?
Acidosis due to decreased bicarbonate or increased fixed acid
What compensatory mechanism occurs in respiratory acidosis?
Kidneys retain bicarbonate and excrete hydrogen ions (H+)
What are common causes of respiratory alkalosis?
- Hyperventilation
- Anxiety
- Pain
- CNS disorders
- Fever
- High altitude
What is the treatment for metabolic alkalosis?
Address fluid and electrolyte imbalances
True or False: Sodium bicarbonate should be used for respiratory acidosis.
False
What is the significance of the P/F ratio in ARDS severity?
- Mild: 200-300
- Moderate: 100-200
- Severe: <100
What is the primary buffer system in blood?
Bicarbonate (HCO3-)
What is the chloride shift (Hamburger effect)?
HCO3- leaves RBCs in exchange for Cl-
What is the PaCO2 range for normal arterial blood gases?
35 - 45 mmHg
What is the effect of increased CO2 on pH?
Lower pH (Acidosis)
What are the main causes of hypercapnia?
- Rebreathing of CO2
- Exhausted CO2 absorbent
- Faulty expiratory valves
- Inadequate capnography
What is the compensatory response to metabolic acidosis?
Hyperventilation to decrease PaCO2
What is a common treatment for severe metabolic acidosis?
Dialysis is preferred over sodium bicarbonate
What are the components of the acid-base buffer systems?
- Bicarbonate
- Phosphate
- Proteins
What are the arterial blood gas (ABG) findings in uncompensated respiratory acidosis?
↓ pH, ↑ PaCO2, normal HCO3-
What does the base excess (BE) measure?
Amount of acid or base needed to return blood pH to 7.4 at a PaCO2 of 40 mmHg
What is the effect on pH when HCO₃⁻ increases?
pH increases by 0.15 units
What characterizes Uncompensated Metabolic Alkalosis?
Increased HCO₃⁻ with normal PaCO₂
What are common causes of Uncompensated Metabolic Alkalosis?
- Vomiting
- Nasogastric suction
- Diuretic therapy
- Excessive bicarbonate intake
How does the body compensate for Metabolic Alkalosis?
Hypoventilation to retain CO₂
What is the treatment focus for Metabolic Alkalosis?
Address fluid and electrolyte imbalances
What defines Mixed Acidosis?
Combination of respiratory and metabolic acidosis
What are common causes of Mixed Acidosis?
- Cardiac arrest
- Severe shock
- Multiple organ failure
What is the treatment for Mixed Acidosis?
Address both respiratory and metabolic causes
What defines Mixed Alkalosis?
Combination of respiratory and metabolic alkalosis
What are common causes of Mixed Alkalosis?
Overresuscitation (excessive ventilation and bicarbonate administration)
What is the treatment for Mixed Alkalosis?
Manage underlying causes and reduce ventilation
What is Venous Blood Gas (VBG) analysis?
Included in blood gas analysis, differs from arterial blood gas analysis
When is ABG preferred over VBG?
When assessing oxygenation and precise respiratory function
What is the clinical use of Mixed Venous Blood Gas (SvO₂)?
Reflects global tissue oxygen consumption and delivery
What does a low SvO₂ indicate?
- Increased oxygen extraction
- Decreased cardiac output
- Low oxygen delivery
- Increased oxygen consumption
What does a high SvO₂ indicate?
- Decreased oxygen extraction
- Sepsis
- Cyanide poisoning
- Left-to-right shunts
How does ScvO₂ differ from SvO₂?
ScvO₂ is drawn from the superior vena cava and is typically ~2-3% higher than SvO₂
What is the definition of Evoked Potentials (EPs)?
Measurable electrical responses generated by the nervous system following a specific stimulus
What is the purpose of Evoked Potentials?
Evaluate the functional integrity of neural pathways
What are the types of Evoked Potentials?
- Somatosensory EPs
- Motor EPs
- Brainstem Auditory EPs
- Visual EPs
What is latency in the context of Evoked Potentials?
The time delay between stimulus and neural response
What does reduced amplitude in Evoked Potentials indicate?
Nerve damage, demyelination, or ischemia
What are Somatosensory Evoked Potentials (SSEPs) used for?
Evaluate sensory pathways and detect peripheral nerve damage
What anesthesia considerations are important for SSEPs?
Volatile anesthetics decrease amplitude and increase latency
What are Motor Evoked Potentials (MEPs) used for?
Evaluate the corticospinal pathway and diagnose motor neuron diseases
What are Brainstem Auditory Evoked Potentials (BAEPs) used for?
Assess auditory nerve and brainstem function in response to sound
What is the clinical application of Visual Evoked Potentials (VEPs)?
Detect optic nerve disorders and monitor nerve integrity
How do inhalational anesthetics affect Evoked Potentials?
Decrease amplitude and increase latency
What is the effect of inhalational anesthetics on evoked potentials (EPs)?
↓ Amplitude, ↑ Latency – Depresses EP signals, affecting accuracy. Particularly problematic for MEPs & VEPs.
MEPs are motor evoked potentials and VEPs are visual evoked potentials, which are highly sensitive to suppression by anesthetics.
What is the recommended concentration of inhalational anesthetics for critical EP monitoring?
Lower concentrations or avoidance recommended; may be acceptable at ≤ 0.5 MAC for SSEP monitoring.
MAC stands for Minimum Alveolar Concentration.
How do intravenous anesthetics (TIVA) affect evoked potentials?
Preserves amplitude & latency better than inhaled agents, allowing for more stable EP signal recordings.
TIVA stands for Total Intravenous Anesthesia.
Why is TIVA preferred for surgeries requiring robust EP monitoring?
It provides better preservation of amplitude and latency of evoked potentials.
Ideal for spinal, neurosurgical, and vascular procedures.
What is the effect of muscle relaxants (NMBs) on evoked potentials?
No direct effect on neural pathways, but suppresses muscle responses in MEPs.
NMBs are neuromuscular blockers.
What is the clinical implication of using muscle relaxants during MEP monitoring?
MEPs require minimal or no muscle relaxants to maintain response integrity.
SSEPs and BAEPs are not affected by neuromuscular blockade.
What physiological factors can mask evoked potential waveforms?
Hypothermia, age, neurological conditions, and sedation can cause response variability.
These factors can lead to misinterpretation of the waveforms.
What are the interpretation challenges associated with evoked potential waveforms?
Require specialized neurophysiologist analysis; small changes may indicate significant neurological alterations.
What is the importance of evoked potentials in clinical and surgical settings?
Critical for assessing neural pathways; provide valuable insights into sensory, motor, auditory, and visual function.
What must anesthetic management balance during procedures involving evoked potentials?
Ensuring adequate anesthesia while preserving EP signal quality for accurate monitoring.
Why is effective teamwork essential in the context of evoked potentials?
Continuous collaboration between anesthesia providers, surgeons, and neuromonitoring specialists is necessary for optimal patient outcomes.
True or False: Evoked potentials are not affected by high opioid doses.
False
MEPs are highly affected by muscle relaxants, volatile anesthetics, and high opioid doses.
Fill in the blank: TIVA is preferred to maintain signal quality because it _______.
[preserves amplitude and latency better than inhaled agents].
What is the normal range for Intracranial Pressure (ICP) in adults?
5-15 mmHg
What is the definition of Cerebral Blood Flow (CBF)?
Amount of blood that circulates through the brain per minute
What is the normal value for Cerebral Blood Flow (CBF)?
50 mL/100g/min
What ICP value is considered as Intracranial Hypertension?
ICP > 20-25 mmHg
What is the formula for Cerebral Perfusion Pressure (CPP)?
CPP = MAP – ICP
What is the normal range for Cerebral Perfusion Pressure (CPP)?
80-100 mmHg
What does the Monro-Kellie Doctrine describe?
The pressure-volume equilibrium between the brain, blood, and CSF
What are pathological causes of increased ICP volume?
- Brain swelling/edema
- Tumor
- Increased cerebral blood flow
- Bleeding
- Increased CSF production
- Reduced CSF removal
What are transient causes of increased ICP?
- Coughing
- Valsalva maneuver
- Steep Trendelenburg position
What are the signs and symptoms of Intracranial Hypertension?
- Headache
- Nausea and vomiting
- Papilledema
- Pupil dilation
- Focal neurologic deficit
- Altered ventilatory function
- Hemiplegia
- Seizure
- Coma
- Cushing’s Triad
What are the indications for ICP monitoring?
- Severe Traumatic Brain Injury (TBI) with GCS ≤ 8
- Normal CT scan but ≥2 risk factors
- Sedated or induced coma patients after severe TBI
- Multisystem injury with altered level of consciousness
- Postoperative monitoring after intracranial mass removal
True or False: ICP monitoring is required for conscious, alert patients with TBI.
False
What is the gold standard method for ICP measurement?
Intraventricular Catheter (External Ventricular Drain/EVD/Ventriculostomy)
What is the normal ICP waveform P1 called?
Percussion Wave
What does an elevated ICP waveform pattern indicate?
Reduced compliance
What is the goal of anesthetic management for neurosurgical patients?
To promote adequate oxygenation and nutrient supply by maintaining ICP, CPP, MAP
Fill in the blank: The normal ICP range is ______.
5-15 mmHg
What is the risk associated with the Intraparenchymal Probes method of ICP monitoring?
Cannot drain CSF
What are the anesthetic considerations during induction for neurosurgical patients?
- Preinduction measures: arterial catheterization, osmotic diuresis, CSF drainage
- Short-acting opioid and lidocaine administration
- Strict blood pressure control
What is the recommended tidal volume for ventilation in neurosurgical patients?
6-8 mL/kg
What should be avoided in fluid management for neurosurgical patients?
Hypotonic solutions (e.g., LR)
What is Cushing’s Triad?
Hypertension, bradycardia, irregular respirations
What is the importance of maintaining serum glucose levels in neurosurgical patients?
Hyperglycemia negatively impacts cerebral metabolism
What is the primary factor that influences CBF and oxygen delivery to the brain?
Cerebral Perfusion Pressure (CPP)
What are the clinical significance of abnormal ICP patterns like Plateau Waves?
Indicates critically low intracranial compliance and ischemia risk
What type of fluids should be used for volume replacement in neurosurgery?
Hypertonic fluids (e.g., 0.9% NaCl)
Avoid hypotonic solutions (like LR) to prevent cerebral edema.
What is the target serum glucose level to maintain during neurosurgery?
90-180 mg/dL
Hyperglycemia negatively impacts cerebral metabolism.
What is a potential treatment for moderate-severe hyponatremia in neurosurgical patients?
3% saline
Administer slowly (50-100 mL/hr) and monitor serum sodium hourly.
What should be avoided to prevent central pontine myelinolysis during sodium correction?
Rapid correction (>3–4 mEq/L/hr)
This can lead to serious neurological complications.
What are some common antihypertensives used during neurosurgery?
- Labetalol
- Esmolol
- Nicardipine
- Clevidipine
These are often required for blood pressure management.
What should be strictly avoided during emergence to prevent increased intracranial pressure (ICP)?
Coughing
Coughing can lead to ICP spikes and bleeding.
What is the purpose of using Propofol in neurosurgery?
To induce burst suppression before planned ischemia
Particularly useful in surgeries like aneurysm repair.
Which anesthetic is preferred for neurosurgical cases due to minimal impact on ICP?
Sevoflurane
It causes the least cerebral vasodilation.
What effect does nitrous oxide have on neurosurgical patients?
Variable effects on CBF, CMRO₂, and ICP
It may increase CBF by 100% (~0.5 MAC) but should be avoided in patients with pneumocephalus.
What is the role of external ventricular drainage (EVD) in ICP management?
To relieve pressure
It is a standard treatment for hydrocephalus.
What is the target serum sodium level when using hypertonic saline for ICP control?
145-155 mEq/L
Do not administer if Na⁺ > 155 mEq/L to avoid complications.
What is the common regimen for corticosteroids used in managing vasogenic cerebral edema?
Dexamethasone 4 mg IV q6h
It is not used in TBI due to potential harm.
What is a significant risk of using mannitol for ICP control?
Hyperosmolality and electrolyte imbalance
These risks may be attenuated with loop diuretics.
What should be monitored continuously during barbiturate coma for refractory ICP cases?
Continuous EEG
This helps to induce burst suppression and maintain low ICP.
What is the normal range for intracranial pressure (ICP)?
5-15 mmHg
Elevated ICP can indicate serious neurological issues.
What are the indications for ICP monitoring?
- Severe TBI with GCS ≤ 8
- Abnormal CT scan
- Normal CT scan + ≥ 2 risk factors
Risk factors include age > 40 years, decerebrate posturing, and SBP < 90 mmHg.
What is the gold standard for managing elevated ICP?
EVD Placement
It is considered the most effective intervention.
What is a major concern when using high-dose volatile anesthetics in neurosurgery?
They can increase ICP
Isoflurane > Sevoflurane > Desflurane in terms of cerebrovascular effects.
What is the title of the seventh edition of the source?
Nurse Anesthesia
Which company published the seventh edition of Nurse Anesthesia?
Elsevier Inc.
What are the page numbers referenced in the source?
325, 718, 722-724, 819-820
What is the subject of the image from Starship Child Health?
External ventricular drain
What is the website for the guidelines on external ventricular drain?
https://starship.org.nz/guidelines/external-ventricular-drain/
What type of illustration is provided by Vecteezy?
Vector illustration
When was the cute brain icon retrieved from Vecteezy?
February 14, 2025
What URL can be used to access the cute brain icon?
https://www.vecteezy.com/vector-art/2748715-cute-brain-icon
What does BIS stand for in anesthesia monitoring?
Bispectral Index
BIS is a technology used to monitor the depth of anesthesia using EEG signals.
What numerical range does the BIS provide to represent patient consciousness?
0-100
The BIS scale provides a numerical value indicating the level of consciousness during anesthesia.
What is the purpose of monitoring anesthesia depth?
Prevention of intraoperative awareness, optimization of anesthetic dosing, enhancement of patient safety and recovery
What is the Patient Safety Index (PSI)?
Similar to BIS but has a different target range
PSI is used to monitor anesthesia depth, akin to BIS.
What are key components of EEG in anesthesia monitoring?
High frequency beta waves, low frequency waves, EEG suppression, burst suppression
What does a BIS score of 100 indicate?
Fully conscious
What does a BIS score range of 40-65 represent?
General anesthesia
What is the significance of a BIS score below 20?
Burst suppression
What are some advantages of BIS monitoring?
Provides near real-time feedback, may reduce anesthesia drug consumption, may help optimize recovery times
What is a limitation of BIS monitoring related to EEG processing?
Delay in EEG processing may limit real-time responsiveness
True or False: BIS can be affected by the use of Ketamine.
True
How does Ketamine affect BIS readings?
High frequency oscillations rather than slow wave oscillations may occur
What is a challenge when using BIS with Nitrous Oxide?
Readings may be falsely high, leading to overuse of anesthetic
What is a notable pattern seen with Dexmedetomidine in BIS monitoring?
Similar to normal sleep pattern, unable to achieve burst suppression
What populations may BIS monitoring inaccurately interpret?
Adults over 60, children
Older adults have lower amplitude oscillations; children have different frequency band power.
What is intraoperative awareness?
Patient recall of events during anesthesia
BIS monitoring’s effectiveness in reducing intraoperative awareness is controversial.
What are the implications of deep anesthesia (BIS < 40) for over 5 minutes?
Increased postoperative mortality
What is the cost of single-use electrodes for BIS monitoring?
$10-$15 per case
What is the time delay associated with BIS monitoring?
20-30 seconds between EEG waveform and computed BIS index value
What is the main application of Cerebral Oximetry?
Monitoring adequacy of brain oxygenation
What technology does Cerebral Oximetry use?
Near-Infrared Spectrometry (NIRS)
List some clinical indications for Cerebral Oximetry.
- Cardiac surgery
- Carotid endarterectomy
- Neonates
- Provider’s preference
- Neuro Intensive Care Patients
What is the role of the anesthesia provider in Cerebral Oximetry?
Determine appropriateness of the monitoring
What is the primary goal of monitoring cerebral perfusion?
To reduce complications relating to cerebral ischemia
This is crucial in anesthesia practice to ensure patient safety.
What should an anesthesia provider determine regarding monitoring?
The appropriateness of the monitoring application of the device
This involves assessing the patient’s condition and the surgical procedure.
What should be obtained to interpret cerebral oximetry readings?
The patient’s pre-induction baseline
This baseline is essential for accurate monitoring during the procedure.
What is the goal for maintaining cerebral oxygen saturation?
A value minimum of 75% of the baseline
This helps to ensure adequate cerebral perfusion.
What should be set to the goal of maintaining adequate cerebral oxygen saturation?
Alarm limits
This helps in alerting the anesthesia provider of any deviations.
List common causes of decreased cerebral oxygen saturation.
- Impaired oxygen delivery
- Anemia
- Decreased arterial oxygen saturation
- Diminished cardiac output
- Vasospasm
These factors can significantly impact cerebral perfusion.
What factors can decrease the accuracy of cerebral oximetry information?
- Changes in blood pressure
- Variations in regional (brain) blood volume
- Variations in hemoglobin concentration
- Individual variabilities (difference in extra cranial tissue)
These factors can lead to misleading readings.
True or False: Cerebral oximetry is not susceptible to motion artifacts.
False
It is susceptible to motion artifacts and external interference.
What are some limitations of cerebral oximetry?
- Susceptible to motion artifacts and external interference
- Variability between devices
- Interpretation challenges in certain patients
- Cost considerations
These limitations can affect the reliability of the monitoring.
What is the significance of monitoring cerebral perfusion?
It plays a role in improving surgical outcomes
Proper monitoring can lead to better patient safety and recovery.
What should be considered for future research in cerebral oximetry?
Challenges and limitations to address in practice
Innovation in technology and methods is essential for advancing this field.
Fill in the blank: A 72-year-old male with CAD, HTN, DM2, and CKD is scheduled for an off-pump coronary artery bypass graft (OPCABG). Would you use _______ on this patient?
[cerebral oximetry]
This patient’s history suggests a need for careful monitoring.
What intraoperative measures should be used to maintain adequate perfusion?
To be determined based on the patient’s condition and monitoring results
Specific measures will vary depending on real-time data.
