Monitoring Detailed Flashcards
How can oxygenation be monitored in anesthesia practice?
Through clinical observation, pulse oximetry, and ABGs as indicated.
What are the methods used for monitoring ventilation in anesthesia practice?
Auscultation, chest excursion assessment, ETCO2 measurement, pressure monitors as indicated, and RR monitoring every 5 minutes.
What are the cardiovascular monitoring standards during anesthesia?
Include electrocardiogram, BP and HR checks every 5 minutes, and auscultation as needed.
How is thermoregulation monitored during anesthesia?
By monitoring for clinically significant changes in body temperature.
When should neuromuscular monitoring be emphasized during anesthesia practice?
Especially when neuromuscular blocking agents are administered.
What factors determine additional monitoring standards in anesthesia practice?
Patient needs, surgical techniques, or specific procedures.
Why is it important to chart any omission of monitoring with a reason?
To ensure transparency, accountability, and a complete record of care provided.
What is pulse oximetry used for in anesthesia practice?
To monitor oxygen saturation levels in the blood.
What is the Absorbance of Light principle in monitoring standards?
It involves light transmission through matter and measurement of light absorption at specific wavelengths.
What are the operating principles of monitoring adult blood in anesthesia practice?
Involves co-oximetry with 4 wavelengths, measuring different hemoglobin types like Oxyhemoglobin, Reduced Hb, Methemoglobin, Carboxyhemoglobin.
How does 660 nm light behave in pulse oximetry?
It is absorbed more by deoxyhemoglobin than oxyhemoglobin.
What is the role of 940 nm light in pulse oximetry?
It is absorbed more by oxyhemoglobin than deoxyhemoglobin.
How does the pulsatility of arterial blood flow help estimate SaO2 in pulse oximetry?
The pulsatile expansion of the artery increases the length of the light path, enhancing absorbency.
Why is the ratio of AC and DC light absorption important in pulse oximetry?
It allows for the differentiation of the pulsatile component (arterial blood) from the non-pulsatile component.
How does carboxyhemoglobin affect SpO2 readings in pulse oximetry?
Carboxyhemoglobin absorbs light like oxyhemoglobin, leading to falsely elevated SpO2 readings.
What impact does a 1% increase in COHb have on SpO2 readings?
Each 1% increase in carboxyhemoglobin leads to a 1% increase in SpO2 readings.
What are the causes of signal artifact in pulse oximetry?
Signal artifact in pulse oximetry can be caused by ambient light interference, low perfusion, and venous blood pulsations.
How can signal artifacts be resolved in pulse oximetry?
Signal artifacts can be resolved by using alternating red/infrared light, detecting venous O2Hb saturation, and incorporating additional light absorbers.
What is the advantage of pulse oximetry in terms of accuracy?
Pulse oximetry is accurate within +/- 2% when compared to arterial blood gases (saturation > 70%).
What are some advantages of pulse oximetry in terms of monitoring?
Pulse oximetry offers noninvasive and continuous monitoring, indicating decreased cardiac output and being convenient with various probe options.
What are the disadvantages of pulse oximetry related to poor perfusion?
Pulse oximetry poorly functions with poor perfusion, leading to inaccuracies in oxygen saturation readings.
How does pulse oximetry perform with dysrhythmias?
Pulse oximetry shows erratic performance in the presence of dysrhythmias, affecting the accuracy of oxygen saturation readings.
What can cause inaccuracy in pulse oximetry readings related to hemoglobin?
Pulse oximetry may show inaccuracy with different types of hemoglobin, affecting the precision of oxygen saturation measurements.
What is a potential issue for pulse oximetry with dyes?
The presence of dyes can interfere with pulse oximetry readings, leading to inaccuracies in the measurement of oxygen saturation.
Why can nail polish and coverings pose a problem for pulse oximetry?
Nail polish and coverings can cause issues with pulse oximetry readings by obstructing accurate measurement of oxygen saturation.
What is a common challenge in pulse oximetry related to motion?
Motion artifact poses a challenge in pulse oximetry, potentially causing inaccuracies in oxygen saturation readings.
Why should the device not be placed on the index finger during pulse oximetry?
It is advised to avoid placing the pulse oximetry device on the index finger to avoid corneal abrasion from patient rubbing eyes upon emergence.
Where might one get more reliable pulse oximetry readings with epidural blocks?
Toes may provide more reliable pulse oximetry readings, especially in the context of epidural blocks.
What areas are less affected by vasoconstriction and reflect desaturation quicker in pulse oximetry?
The tongue, cheek, and forehead are less affected by vasoconstriction and can reflect desaturation quicker in pulse oximetry.
What information can be found in the reference materials for blood pressure monitoring?
Reference materials like Ehrenwerth and Miller provide detailed information on blood pressure monitoring techniques.
What causes the production of Korotkoff sounds during blood pressure measurement?
Korotkoff sounds are produced by turbulent flow beyond the partially occluded cuff during blood pressure measurement.
How is mean arterial pressure calculated using Korotkoff sounds?
Mean arterial pressure is calculated by adding DBP with one-third of the difference between the systolic pressure and diastolic pressure.
MAP= DBP + 1/3 (SBP - DBP)
What can affect the accuracy of blood pressure auscultation?
Conditions like shock, vasoconstriction, vessel compliance changes, edema, and atherosclerotic vascular changes can impact the accuracy of blood pressure readings.
What guidelines should be followed for cuff placement in blood pressure monitoring?
Cuff bladder size should be 40% of arm circumference and 80% of upper arm length, centered over an artery for accurate blood pressure measurement.
What challenge does obesity present in blood pressure monitoring?
Obesity can make obtaining accurate blood pressure readings challenging due to cuff size limitations and potential inaccuracies.
What is the maximal amplitude of oscillations referred to as in oscillometry?
It is referred to as MAP.
How are SBP and DBP calculated in oscillometry?
They are calculated using algorithms.
In oscillometry, which blood pressure component shows the least agreement with invasive blood pressure?
SBP shows the least agreement.
What are some factors that can introduce errors in oscillometry readings?
Errors can be introduced by atherosclerosis, edema, obesity, and chronic hypertension.
What happens if the cuff used in oscillometry is too large?
It results in a low blood pressure reading.
What is the specified average difference criteria in oscillometry readings?
The average difference must be less than +/- 5 mm Hg.
When is the forearm considered a preferable site for blood pressure estimation?
The forearm may be preferable in obese individuals.
What are some advantages of automatic non-invasive techniques like oscillometry?
Advantages include eliminating clinician subjectivity, improving quality, and being noninvasive.
In invasive blood pressure monitoring, what are the indications for its use?
Indications include continuous monitoring, pharmacologic manipulation, blood sampling, volume responsiveness, and IABP timing.
What is the most common site for invasive blood pressure monitoring?
The radial artery is the most common site.
What is the procedure for Allen’s Test?
The examiner compresses radial and ulnar arteries, and the patient exsanguinates the palm by making a fist and then releases the ulnar artery.
What is the normal outcome of Allen’s Test?
Normal response: Color of palm should return in seconds.
What is the abnormal outcome of Allen’s Test?
Abnormal response: Severely reduced collateral flow if color change takes more than 10 seconds.
What is the accuracy of Allen’s Test?
Approximately 80% accurate.
How do pulse oximetry and ultrasound affect the accuracy of Allen’s Test?
They do not improve accuracy.
What are the key steps in the Transfixion Technique?
Similar to Allen’s Test preparation, intentionally puncturing front and back walls with a needle to advance a catheter with pulsatile blood flow.
Are there frequent complications associated with the Transfixion Technique?
It is not associated with more frequent complications.
What are the functions of an arterial line?
Provides automatic flush to the nervous system, prevents thrombus formation with an infusion rate of 1 - 3 ml/hr, and requires lack of dextrose and heparin.
How is calibration of an arterial line performed?
Zeroing references pressures against atmospheric air, and leveling ensures accurate readings.
What optimization strategies are recommended for arterial line placement?
Positioning in the aortic root for waveform maximization, using non-distensible tubing, and limiting stopcocks and tubing length.
What are the components of arterial waveforms?
Include systolic upstroke, systolic peak pressure, systolic decline, dicrotic notch, diastolic runoff, and end-diastolic pressure.
What are the characteristics of distal pulse amplification?
Arterial pressures vary at different sites with distinct morphologies, influenced by impedance and harmonic resonance along the vascular tree.
What changes occur in the pressure wave as it moves towards the periphery?
Arterial upstroke becomes steeper, systolic peak increases, dicrotic notch delays, and end-diastolic pressure decreases.
How are arterial waveforms generated?
Through the summation of sine waves, combining fundamental and harmonic waves, utilizing Fourier analysis for waveform analysis.
What are the characteristics of underdamped systems in arterial pressure dynamics?
Underdamped systems exhibit elevated systolic pressure.
What are the characteristics of overdamped systems in arterial pressure dynamics?
Overdamped systems exhibit decreased systolic pressure, absence of dicrotic notch, loss of detail in pressure waveform, and falsely narrowed pulse pressure with MAP accuracy.
How does age affect pressure gradients in clinical settings?
Age-related reduced distensibility impacts pressure gradients.
In what way does atherosclerosis influence pressure gradients in clinical settings?
Atherosclerosis alters peripheral vascular resistance affecting pressure gradients.
What impact do septic shock and hypothermia have on pressure gradients?
Septic shock and hypothermia can influence pressure gradients in clinical settings.
What are some potential complications associated with arterial lines?
Complications include distal ischemia or pseudoaneurysm, hemorrhage, hematoma, arterial embolization, local infection, and peripheral neuropathy.
Why is pressure waveform analysis important in clinical settings?
It helps identify residual preload reserve, understand cyclic arterial blood pressure variations, and assess effects of positive pressure ventilation on lung volume changes.
How does positive pressure ventilation (PPV) affect pressure during the inspiratory phase?
PPV increases intra-thoracic pressure, impacts LV afterload, lung volume, LV preload, stroke volume, CO, systemic arterial pressure, systemic venous return, RV preload, afterload, and PVR.
What effects does positive pressure ventilation (PPV) have on pressure during the expiratory phase?
Expiratory phase effects include decreased RV stroke volume, reduced LV filling, stroke volume, and systemic arterial blood pressure, introducing Systolic Pressure Variation (SPV).
What is the normal range for Systolic Pressure Variation (SPV)?
The normal SPV range is 7 - 10 mm Hg, with the ‘Up’ component ranging from 2 - 4 mm Hg and the ‘Down’ component ranging from 5 - 6 mm Hg.
What does an increased Systolic Pressure Variation (SPV) indicate in mechanically ventilated patients?
An increased SPV suggests volume responsiveness or residual preload reserve, and it can be an early indicator of hypovolemia.
How do critically ill patients often exhibit Systolic Pressure Variation (SPV)?
Critically ill patients may show a dramatic increase in SPV, especially in the Down component.
What does Pulse Pressure Variation (PPV) measure?
PPV uses the maximum and minimum pulse pressures across the respiratory cycle, with a normal range below 13 - 17%.
What does a Pulse Pressure Variation (PPV) value of >13 - 17% indicate?
PPV >13 - 17% suggests a positive response to volume expansion in mechanically ventilated patients.
How is Stroke Volume Variation (SVV) calculated?
SVV is calculated as (SV max - SV min) / SV mean, with a normal range of 10 - 13% in determining volume responsiveness.
What factors does Stroke Volume Variation (SVV) correlate with in mechanically ventilated patients?
SVV correlates with resistance and compliance based on age, gender, and hemodynamic status.
What conditions are necessary for predicting accurate results with hemodynamic parameters in mechanically ventilated patients?
Accurate predictions require mechanical ventilation with 8 to 10 mL/kg tidal volume, 5 mm Hg PEEP, regular cardiac rhythm, normal intra-abdominal pressure, and a closed chest.
What is the purpose of gas mixture analysis in gas sampling systems?
Gas must be transported to the analyzer for analysis.
How does a side-stream or diverting analyzer function in gas sampling systems?
The analyzer is brought to the gas in the airway.
Provide an example of a mainstream or non-diverting analyzer in gas sampling systems.
One example is the fuel cell oxygen analyzer.
What does ‘total response time’ refer to in gas sampling systems?
It refers to the transit time, which is the time lag for the gas sample to reach the analyzer.
Define ‘rise time’ in the context of gas sampling systems.
It is the time taken by the analyzer to react to the change in gas concentration.
What factors influence side-stream responses in gas sampling systems?
Side-stream responses are dependent on sampling tubing inner diameter, length, and gas sampling rate.
What challenges are associated with mainstream gas sampling systems?
Challenges include dealing with water vapor, secretions, blood, and more interfaces for disconnections.
What are some challenges faced in side-stream gas sampling systems?
Challenges involve kinking of sampling tubing, water vapor, failure of sampling pump, leaks in the line, and slow response time.
Explain Dalton’s Law and its relevance in gas mixtures.
Dalton’s Law states that the total pressure of a gas mixture equals the sum of the partial pressures exerted by each gas in the mixture.
What units of measurement are used for anesthetic gases at sea level?
At sea level, anesthetic gases are measured in total pressure (760 mm Hg), partial pressure (mm Hg), and volumes %.
How is the oxygen content in room air expressed in units of measurement?
Oxygen in room air has a partial pressure of 160 mm Hg, equivalent to 21 volumes %.
How is concentration determined in Mass Spectrometry?
Concentration in Mass Spectrometry is determined based on mass/charge ratio.
What does Abundance Analysis in Mass Spectrometry determine?
Abundance Analysis in Mass Spectrometry determines the fractional composition of gas mixtures at specific mass/charge ratios.
How many different gases can Mass Spectrometry calculate concentrations for?
Mass Spectrometry is capable of calculating concentrations of up to eight different gases.
What is the principle behind Raman Spectroscopy?
Raman Spectroscopy involves a high powered argon laser generating photons that interact with gas molecules in a sample.
How are scattered photons used in Raman Spectroscopy?
Scattered photons in Raman Spectroscopy are analyzed in a spectrum to identify each gas and its concentration.
What gases can be detected using Infrared Analysis?
Infrared Analysis can measure CO2, nitrous oxide, water, and volatile anesthetic gases due to their absorption characteristics.
Why can’t O2 be detected using Infrared Analysis?
O2 cannot be detected using Infrared Analysis as it does not absorb infrared radiation.
What does the unique infrared transmission spectrum absorption band indicate for each gas?
The unique infrared transmission spectrum absorption band serves as a spectral fingerprint for each gas.
How does the measurement process work for detecting gases based on infrared absorption bands?
In the measurement process, infrared light is transmitted through a gas sample across various frequencies, filtered using a narrow-band pass filter.
What relationship exists between the gas concentration and the infrared light intensity in gas analysis?
The relationship is that the amount of infrared light reaching the detector is inversely proportional to the gas concentration, where lower light intensity indicates higher gas concentration.
What are the typical values reported by side-stream analyzers?
Side-stream analyzers typically report ambient temperature and pressure dry (ATPD) values.
What are the recommeneded conditions that oxygen analyzers should ideally report results?
Analyzers should report results at body temperature and pressure saturated (BTPS) values.
What is the equivalent saturated H2O vapor pressure at 760 mmHg?
The saturated H2O vapor is equivalent to 47 mm Hg at 760 mmHg.
How can you calculate the partial pressure of O2 at a certain concentration using a specific formula?
To calculate the partial pressure of O2 at a certain concentration (e.g., 30%), use the formula: (760 - 47) * (0.3) = 214 mm Hg.
What are the two types of cells oxygen analyzers can use?
Oxygen analyzers can utilize a fuel or galvanic cell to measure the current generated as oxygen diffuses across a membrane.
What is the relationship between the current produced and the partial pressure of oxygen in fuel or galvanic cell analyzers?
The current produced is directly proportional to the partial pressure of oxygen in the fuel or galvanic cell.
What are some characteristics of oxygen analyzers utilizing fuel or galvanic cells?
These analyzers have a short lifespan (months) depending on oxygen exposure and exhibit a slow response time of approximately 30 seconds.
Where is it advisable to monitor O2 concentration for optimal results with oxygen analyzers?
It is advisable to monitor O2 concentration in the inspiratory limb for optimal results with oxygen analyzers.
Why is oxygen considered a highly paramagnetic gas?
Oxygen is considered a highly paramagnetic gas due to the magnetic energy of unpaired electrons in its outer shell orbits.
How do paramagnetic analyzers detect changes in O2 concentration?
Paramagnetic analyzers detect changes in sample line pressure caused by the attraction of oxygen to switched magnetic fields.
What is the significance of signal variations during switching in paramagnetic analyzers?
The signal variations during switching in paramagnetic analyzers are directly related to the O2 concentration being measured.
Where are paramagnetic oxygen analyzers commonly used and for what purposes?
Paramagnetic oxygen analyzers are commonly used in side-stream sampling multi-gas analyzers for rapid response and breath-by-breath monitoring.
Why is oxygen monitoring considered arguably the most important monitor in anesthesia?
Oxygen monitoring is crucial for maintaining proper oxygen levels which are essential for patient safety and wellbeing during anesthesia.
Why is calibration for high and low concentrations important in oxygen monitoring?
Calibration ensures the accuracy of oxygen concentration readings, which is vital for adjusting oxygen delivery as needed.
How does sampling inside the inspiratory limb ensure proper oxygen delivery?
Sampling inside the inspiratory limb allows for analysis of the oxygen content being delivered to the patient during inspiration.
What does analyzing hypoxic mixtures in oxygen monitoring aim to achieve?
It aims to maintain optimal oxygen levels in the inspired air to prevent hypoxia and ensure adequate oxygenation of the patient.
Why is sampling inside the expiratory limb essential in oxygen monitoring?
It ensures complete pre-oxygenation denitrogenation by monitoring the oxygen content being exhaled by the patient.
What ET O2 level is considered adequate during anesthesia?
An ET O2 level above 90% is considered adequate to ensure proper oxygenation of the patient.
Why is it not recommended to have oxygen monitoring at auxiliary sites?
Oxygen monitoring should be centralized to critical locations to ensure accurate and reliable readings for patient safety.
Why is a low O2 alarm crucial in oxygen monitoring?
It is essential to promptly alert healthcare providers of low oxygen levels to prevent hypoxemia and its associated risks.
What issues can lead to a low O2 alarm in oxygen monitoring?
Pipeline crossover, incorrectly filled tanks, and failure of a proportioning system are some factors that can trigger a high O2 alarm.
What special considerations are needed for premature infants in oxygen monitoring?
Premature infants require extra caution in oxygen monitoring due to their unique physiological characteristics and sensitivity to oxygen levels.
Why is airway pressure monitoring a key component in anesthesia?
It is crucial for assessing ventilation during anesthesia, helping detect and prevent complications related to airway pressure.
What issues can be detected using airway pressure monitoring?
Circuit disconnections, ETT occlusions, kinking in the inspiratory limb, leaks, sustained high circuit pressure, and scavenging system pressures.
What are the characteristics of mechanical pressure gauges used in airway pressure monitoring?
They are reliable, require no power source, lack data recording and alarm systems, but serve the purpose effectively.
How do electronic pressure gauges differ from mechanical pressure gauges in airway pressure monitoring?
Electronic pressure gauges are integrated into machines, sensitive to small changes, and equipped with built-in alarm systems for immediate alerts.
Why is continuous scanning necessary for both mechanical and electronic pressure gauges in airway pressure monitoring?
Continuous scanning ensures real-time monitoring of airway pressure changes to promptly identify and address any ventilation issues.
What is the primary purpose of a breathing circuit low-pressure alarm in airway pressure monitoring?
It aims to detect circuit disconnections or leaks that could compromise proper ventilation, ensuring patient safety.
Where do the majority of disconnections occur that need to be monitored by a low-pressure alarm in airway pressure monitoring?
The majority of disconnections occur at the Y-piece junction, emphasizing the importance of monitoring this area for leaks or issues.
What does a sub-atmospheric pressure alarm measure and alert?
It measures and alerts negative circuit pressure and the potential for reverse gas flow.
What are the effects of negative pressures as indicated by sub-atmospheric pressure alarms?
Negative pressures can cause pulmonary edema, atelectasis, and hypoxia.
List some causes of sub-atmospheric pressure alarms.
Causes include malfunctioning suction systems, patient inspiratory effort against blockages, inadequate gas flow, suction to misplaced tubes, and moisture in CO2 absorbent.
How are high-pressure alarms activated?
They are activated when the pressure exceeds a specified limit.
In what cases are high-pressure alarms particularly valuable?
High-pressure alarms are particularly valuable in pediatric cases.
Name some causes that may trigger high-pressure alarms.
Causes include obstructions, reduced compliance, coughing/straining, kinked ETT, and endobronchial intubation.
When are continuing pressure alarms triggered?
They are triggered when circuit pressure exceeds 10 cm H2O for more than 15 seconds.
What happens when continuing pressure alarms are activated?
Fresh gas continues to enter the circuit but cannot leave.
Provide some causes that can lead to the triggering of continuing pressure alarms.
Causes may include malfunctioning pressure relief valves, scavenging system occlusion, oxygen flush system activation, and malfunctioning PEEP valves.
What types of monitoring are included in peripheral nerve monitoring?
It includes electrical nerve stimulation and magnetic monitoring.
How does muscle fiber response differ from whole muscle response in monitoring?
Muscle fiber response follows an all-or-none pattern, while whole muscle response depends on the activation of muscle fibers.
What are the sites of nerve stimulation mentioned?
Ulnar, median, posterior tibial, common peroneal, and facial nerves.
How is the ulnar nerve described in terms of accessibility for stimulation?
Easily accessible, with the adductor pollicis muscle being easily reachable.
What are the advantages of the nerve stimulation sites discussed?
They are easily accessible, allow quantitative monitoring, and help avoid direct muscle stimulation.
Which muscle is highlighted as the most resistant to neuromuscular blocking drugs?
The diaphragm is the most resistant to depolarizing and nondepolarizing neuromuscular blocking drugs.
How does the muscle response of sites like the corrugator supercilii compare to peripheral muscles in terms of onset and recovery?
They have a shorter onset and quicker recovery compared to peripheral muscles.
What specific advantage does the corrugator supercilii muscle have over the adductor pollicis muscle?
Corrugator supercilii better reflects neuromuscular block of laryngeal adductor and abdominal muscles.
Describe the single twitch pattern in nerve stimulation.
It is the earliest and simplest pattern with single stimuli applied from 1.0 Hz to 0.1 Hz.
What is the importance of the single twitch pattern in nerve stimulation?
It provides a reference value necessary before administering neuromuscular blocking drugs (NMBDs).
How many supramaximal stimuli are involved in a Train of Four stimulation pattern?
Four supramaximal stimuli are used every 0.5 seconds in a Train of Four pattern.
What does the Train of Four evaluation assess in muscle response?
It evaluates the TOF count or fade in muscle response.
How is the TOF ratio calculated in a Train of Four scenario?
It is calculated as the 4th response divided by the 1st response in a Train of Four stimulation.
How does the TOF ratio change in a partial nondepolarizing block?
In a partial nondepolarizing block, the TOF ratio decreases (fade) and is inversely proportional to the block degree.
When does a Phase II Block develop according to the Train of Four assessment?
A Phase II Block develops if fade is observed during the Train of Four evaluation.
What is Double Burst Stimulation (DBS) in neuromuscular blockade assessment?
It involves 2 short bursts of 50 Hz tetanic stimulation separated by 750 ms, used for comparison of muscle contractions.
Explain the DBS 3,3 mode in neuromuscular blockade assessment.
It consists of 3 impulses in each of the 2 bursts during Double Burst Stimulation.
Describe the DBS 3,2 mode used in neuromuscular blockade assessment.
In this mode, the 1st burst contains 3 impulses, while the 2nd burst has 2 impulses for comparison.
How are muscle contractions observed in Double Burst Stimulation?
Two short muscle contractions are seen with fade in the 2nd burst, enabling comparison.
What is the clinical usage of Double Burst Stimulation?
It is less commonly used in clinical practice compared to other stimulation patterns.
What is Tetanic Stimulation and how is it administered?
It involves administering 50 Hz stimulation for 5 seconds, inducing muscle contractions with specific characteristics.
Differentiate the effects of Tetanic Stimulation for non-depolarizers and depolarizers.
Non-depolarizers lead to a strong sustained muscle contraction with fade, while depolarizers result in sustained contraction without fade.
What characterizes Phase II Block in Tetanic Stimulation?
It is characterized by fade after stimulation, but its value for recovery assessment is limited due to pain.
In what instances is Tetanic Stimulation less frequently employed in clinical practice?
Tetanic Stimulation is less frequently used compared to other methods due to its limited utility and practical considerations.
What is Post-tetanic Stimulation and how is the stimulation pattern defined?
It involves tetanic stimulation followed by 10 to 15 single twitches after a specific time gap, used for deep blockade assessment.
What factors influence the response during Post-tetanic Stimulation?
Response is affected by the degree of blockade, tetanic stimulation frequency/duration, and gap between tetanic and post-tetanic stimulation.
What is the suggested frequency for utilizing Post-tetanic Stimulation in blockade assessment?
It is recommended to be performed every 6 minutes for effective assessment of deep and surgical blockade.
Describe an intense blockade in non-depolarizing neuromuscular blockade during anesthesia.
It involves a period of no response, occurring 3-6 minutes after the intubating dose, where neostigmine reversal is impossible and high-dose sugammadex is needed.
Explain deep blockade in non-depolarizing neuromuscular blockade in anesthesia.
Deep blockade is characterized by the absence of TOF responses but at least one response to post-tetanic count stimulation, with neostigmine reversal usually impossible and requiring sugammadex.
What is moderate blockade in non-depolarizing neuromuscular blockade and anesthesia?
Moderate blockade is indicated by the gradual return of the 4 responses to TOF stimulation, allowing for neostigmine reversal after 4/4 TOF or with a dose of sugammadex.
Define Phase I in depolarizing blockade during anesthesia.
Phase I is marked by a lack of fade or tetanic stimulation, all 4 responses being reduced and disappearing simultaneously in TOF, and normal plasma cholinesterase activity.
Describe Phase II in depolarizing blockade in anesthesia.
Phase II involves fade in response to TOF and tetanic stimulation, post-tetanic facilitation, and abnormal plasma cholinesterase activity, resembling non-depolarizing blockade.
What are some considerations for using neuromuscular blockade in clinical practice?
Keep the patient warm, attach electrodes before induction, ensure moderate blockade for surgery, reverse at 4/4 TOF responses, and check for neuromuscular recovery post-reversal.
What are reliable clinical signs for assessing neuromuscular recovery?
Sustained head lift, leg lift, handgrip for 5 sec, tongue depressor test, and maximum inspiratory pressure.
What does the summation of excitatory and inhibitory post-synaptic potentials in the cerebral cortex indicate in EEG concepts?
It signifies the electrical activity within the brain and is a fundamental concept in EEG interpretation.
How are electrodes positioned in EEG to relate to cortical regions?
Electrodes are strategically placed to capture electrical signals from specific areas of the brain’s cortex.
How many channels of information are typically utilized in EEG?
At least 16 channels of information are employed to gather comprehensive data from different brain regions.
What are some of the states identified by EEG, in terms of consciousness and brain activity?
EEG can identify consciousness, unconsciousness, seizure activity, stages of sleep, coma, and detect inadequate oxygen delivery to the brain.
What aspects of a signal does EEG description typically include?
EEG signal description includes amplitude (voltage size), frequency (oscillation rate), and time (duration of signal sampling).
How does EEG help in detecting inadequate oxygen delivery to the brain?
EEG can identify inadequate oxygen delivery by recognizing patterns associated with hypoxemia or ischemia in the brain’s electrical activity.
What is the main purpose of EEG in peri-operative settings?
In peri-operative settings, EEG helps identify inadequate blood flow to the brain, guides anesthetic-induced reduction of cerebral metabolism, predicts neurologic outcomes, and measures hypnotic depth.
What brain states do Beta, Alpha, Theta, and Delta waves in EEG represent?
Beta waves (> 13 Hz) indicate an awake and alert brain, Alpha waves (8-13Hz) signify eyes closed or anesthetic effects, while Theta (4-7 Hz) and Delta (< 4Hz) indicate depressed brain states.
What is the significance of processed EEG in neurological monitoring?
Processed EEG helps differentiate unilateral from bilateral changes, detects artifacts, and can be used for conditions like regional ischemia or anesthetic effects.
How many channels of information does processed EEG typically use, and why is this number significant?
Processed EEG uses less than 4 channels, with 2 channels per hemisphere, allowing for the assessment of both brain hemispheres for certain conditions.
What are some examples where processed EEG can provide insights not easily observable in traditional EEG?
Processed EEG can reveal regional ischemia due to carotid clamping (unilateral) and EEG depression from anesthetic drug bolus (bilateral).
What is the key difference between EEG and processed EEG?
While EEG uses multiple channels for detailed brain activity monitoring, processed EEG focuses on simplified analysis with fewer channels, often for specialized evaluations.
What is the availability of studies comparing EEG and processed EEG?
There are limited studies comparing EEG (considered the gold standard) with processed EEG, highlighting the need for further research in this area.
What is the Bispectral Index (BIS) used for?
It processes EEG signals to estimate anesthetic depth using a computer-generated algorithm.
What was the initial purpose of suggesting the Bispectral Index (BIS) technique?
It was suggested as a technique to prevent intraoperative awareness.
How does the Bispectral Index (BIS) compare with end-tidal agent concentration monitoring?
Comparison did not show superiority over end-tidal agent concentration monitoring.
Why are neither the Bispectral Index (BIS) nor end-tidal agent concentration monitoring completely reliable in cases of intraoperative awareness?
These techniques were found to be not completely reliable in preventing intraoperative awareness.
What are Sensory-Evoked Responses commonly monitored for intraoperatively?
They are commonly monitored for CNS responses to electric, auditory, or visual stimuli.
How are responses recorded in Sensory-Evoked Responses along the sensory pathway to the cerebral cortex?
Responses are recorded at various sites along the sensory pathway to the cerebral cortex.
What are the two types of responses in Somatosensory-Evoked Potentials (SSEPs)?
Short-latency and long-latency waveforms are the two types of responses.
What factors can alter the appearance of SSEPs?
Factors such as induction, neurological conditions, age, and electrode locations can alter SSEP appearance.
What is the purpose of monitoring Brainstem Auditory-Evoked Potentials (BAEPs) in intraoperative neurophysiological monitoring?
To assess auditory pathway integrity by monitoring responses to click stimuli delivered along the auditory pathway.
How are click stimuli delivered in Brainstem Auditory-Evoked Potentials (BAEPs)?
Click stimuli are delivered via foam ear inserts.
What is the key characteristic of Visual-Evoked Potentials (VEPs) in intraoperative neurophysiological monitoring?
It evaluates visual pathway function through responses to flash stimulation of the retina using embedded LEDs.
How is flash stimulation delivered in Visual-Evoked Potentials (VEPs)?
Flash stimulation is administered through closed eyelids or contact lenses.
What aspect of Motor-Evoked Potentials (MEPs) is assessed through Transcranial MEPs?
Transcranial MEPs evaluate the integrity of motor tracts via electrical stimulation over the motor cortex.
What is the primary purpose of Electromyography (EMG) in intraoperative neurophysiological monitoring?
EMG monitors responses of cranial and peripheral motor nerves for early detection of nerve damage and assessment of function.
What is the role of the hypothalamus in temperature control during intraoperative monitoring?
The hypothalamus serves as the primary thermoregulatory control center.
What types of receptors are involved in thermoregulation involving temperature control?
Unmyelinated C fibers for heat and warmth receptors, and Alpha-delta fibers for cold receptors.
What are the thermoregulatory response characteristics associated with temperature control?
Threshold (temperature triggering response), gain (intensity of response), and responses like sweating, vasodilation, vasoconstriction, and shivering.
List some factors that can affect the thermoregulatory response during temperature control monitoring.
Factors include anesthesia, age, menstrual cycle, drugs, alcohol, and circadian rhythm.
What is the rate of rapid decrease in temperature with General Anesthesia (GA)?
Approximately 0.5 to 1.5°C initially.
How does anesthesia-induced vasodilation affect heat loss in the body?
It leads to increased heat loss due to the redistribution of body heat.
What is the slow linear reduction in temperature per hour over 30 minutes with General Anesthesia?
Approximately 0.3°C per hour.
How does General Anesthesia affect the metabolic rate?
It decreases the metabolic rate by 20-30%, causing heat loss to exceed production.
When does a plateau phase occur after anesthesia with General Anesthesia?
Around 1-2 hours after anesthesia, reaching thermal steady state with equal heat loss and production.
What occurs 3-4 hours post-anesthesia with General Anesthesia to prevent core heat loss?
Vasoconstriction occurs to prevent core heat loss, while peripheral heat continues to be lost.
How does hypothermia induced by neuraxial anesthesia differ in terms of thermal discomfort?
It does not typically cause significant thermal discomfort, and patients may not complain of feeling cold.
How does neuraxial anesthesia affect central thermoregulatory control?
It inhibits central thermoregulatory control, reducing the triggers for peripheral vasoconstriction and shivering.
What autonomic thermoregulatory defenses are impaired by neuraxial anesthesia?
Vasodilation, sweating, vasoconstriction, and shivering are impaired.
Why may the initial decrease in core temperature not reach a plateau with neuraxial anesthesia?
Due to the inhibition of peripheral vasoconstriction.
How is the threshold for vasoconstriction altered under neuraxial anesthesia?
The threshold for vasoconstriction is centrally altered under neuraxial anesthesia.
What is the significance of infants in relation to heat loss through radiation?
Infants are vulnerable due to their high body surface area to body mass ratio, contributing to approximately 40% of heat loss.
How does convection contribute to heat loss, and how can it be mitigated?
Convection involves the loss of heat to the air immediately surrounding the body, which can be decreased by wearing clothing or using drapes.
What is the main pathway for heat loss through evaporation?
Sweating is the main pathway for heat loss through the evaporation of water, representing approximately 8-10% of total heat loss.
Describe heat loss through conduction and provide an example.
Heat loss through conduction occurs via direct contact of body tissues or fluids with a colder material, such as skin contact with an operating room table.
How does hypothermia contribute to an increase in the need for transfusions and blood loss?
Hypothermia impairs platelet aggregation and coagulation cascade enzymes, leading to a 22% increase in transfusion needs and 16% more blood loss.
What are the implications of hypothermia-induced coagulopathy on oxygen delivery and wound healing?
Coagulopathy decreases oxygen delivery to tissues, increases the risk of wound infection, decreases tissue healing, and raises the incidence of morbid cardiac outcomes.
How does shivering impact oxygen demand and drug metabolism during hypothermia?
Shivering increases oxygen demand, decreases drug metabolism, and prolongs neuromuscular blockade, leading to post-operative thermal discomfort.
What benefits does hypothermia offer in protecting against cerebral ischemia and metabolism reduction?
Hypothermia is protective against cerebral ischemia, reduces metabolism by 8% per degree Celsius, and improves outcomes during recovery from cardiac arrest.
In what medical context is hypothermia found to be beneficial, particularly related to brain tissue ischemia?
Hypothermia is beneficial in neurosurgery where brain tissue ischemia is expected, providing a protective effect against malignant hyperthermia trigger.
Why do infants and children require more attention to temperature management during procedures?
They have higher metabolic rates and smaller body masses, making them more prone to heat loss.
Why is warm IV fluid and blood administration crucial during procedures?
It helps prevent cooling and maintains the patient’s body temperature.
What are examples of procedures where cutaneous warming techniques are essential?
Liver transplants, major trauma cases, and pediatric surgeries.
How can insulation methods like using a single blanket help in temperature management?
They can reduce heat loss by 30% without increasing body temperature.
What makes hot water mattresses effective and safe in peri-operative temperature management?
They are efficient when placed on top of patients to help maintain their body temperature.
How does forced air warming work in preventing heat loss during procedures?
It uses convection to transfer heat to the patient, preventing heat loss through radiation.
Why is pulmonary artery temperature monitoring considered the gold standard?
It correlates well with temperatures measured at other sites like the tympanic membrane, esophagus, and nasopharynx.
What is a risk associated with tympanic membrane temperature monitoring?
There is a risk of perforation during placement.
Which temperature monitoring site reflects brain temperature but is more error-prone?
Nasopharyngeal temperature monitoring.
Why is esophageal temperature monitoring considered safe and accurate?
It is easily accessible, artifact-resistant, and accurate when placed in the distal esophagus.
What are the typical temperature settings in an operating room?
Operating rooms are typically maintained at 70 degrees F (21 degrees C) or 65 degrees F (18 degrees C).
