Intraop Monitoring Flashcards by Jackson Jones

What type of monitoring are you required to use when propofol is administered during endoscopic procedures?

ETCO2

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Crisis management algorithm
COVERABCD

Circulation
Oxygen
Ventilation
Endotracheal Tube
Review monitors/equipment
Airway
Breathing
Circulation
Drugs

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Late stage of hypoxia

Cyanosis

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Capnometry

Encompasses all means of measuring carbon dioxide

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Capnography

The RECORDING of the measurement

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Capnogram

The continuous display of CO2 during ventilation

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Advantages/ disadvantages of non-diverting monitoring of ETCO2

Minimal sampling time delays, fewer disposable items and don’t require scavenging

Only read CO2 and N2O, increase dead space, greater risk of condensation, added weight can cause disconnect

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Diverting CO2 monitoring advantages/disadvantages

Monitor multiple gases, can be used to monitor awake patients, no increase in dead space

Need for scavenging

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Point on capnogram with no CO2

End inspiration and very beginning of expiration- comes from anatomic dead space and contains no CO2

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2nd phase in capnogram

Upstroke of expiration

Rapid passing of expired gas through upper airways

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3rd phase capnogram

Plateau

Records alveoli emptying of CO2

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Fourth phase in capnogram

Rapid decrease in CO2 concentration as result of inspired Air

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Impact of a large ventilation-perfusion ratio

Means large amount of deadspace=low concentration of ETCO2

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V/Q mismatch with small tidal volumes

Also-small tidal volumes (inadequate ventilation) may produce ETCO2 recordings that significantly underestimate arterial CO2

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Causes of failure to return to baseline in ETCO2

Inadequate FGF

Depleted CO2 absorber

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Causes of increased ETCO2

Increased CO2 production- MH, fever, sepsis

Hypoventilation- COPD, paralysis, CNS depression

Equipment- Absorbent, rebreathing

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Causes of Decreased ETCO2

Decreased production- hypotension/volemia, hypometabolism

Hyperventilation- pain/awareness

Equipment- disconnect, esophageal intubation

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Defining intraop hyper and hypothermia

Above 38 or below 36

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Risk factors for perioperative hypothermia

High ASA
Lengthy surgery
eMobile’s epidural/general
Elderly
Lean body mass

FAILURE TO MONITOR TEMP

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Locations considered core temp monitoring

Tympanic membrane
Distal esophagus
Nasopharynx
Pulmonary artery

Maybe bladder

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Bladder temp monitoring

Reflects core temp

Invasive/UTI

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Pulmonary artery temp monitoring

Reflects core temp

Invasive/PA line
Not reliable if chest is open

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Esophageal temp monitoring

Most consider it core

Slight risk of trauma
Inaccurate if too close to stomach
Can’t use in awake patients

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Nasopharynx temp monitoring

Probably core
Easy to insert

Trauma/bleeding
Inaccurate if breathing through nares

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Tympanic temp monitoring

Most consider it core Accurate if contact probe used Easy Slight trauma risk of the membrane Ear wax pusher

Axillary

Reasonably core Easy Not direct core Influenced by IV fluids Easily dislodged

What does an EEG measure?

The brain does NOT emit electrical waves eeg measures the differences in electrical potentials in groups of neurons between brain regions

Basic components of an eeg

Frequency- duration btwn impulses Amplitude- mV peak to peak measurement in a vertical plane Morphology- this seems tricky as waves can be broken down into alpha, beta, delta and theta

2 main reasons eeg is difficult to correlate with patient outcomes

Anesthetic dose related cerebral inhibition Environmental factors-artifact (manipulation of the brain adds to interpretation complexity)

NIRS

Cerebral oximetry via Near-infrared Spectrometry Similar to pulse ox-utilized Beer-lambert Can be impacted by BP, paCO2, blood volume This is meant to be used as a trend and cannot fully reflect cerebral oxygenation-so no true values for cerebral ischemia

Nervous system structures that protect against retraction Elastic limit of nerves

Epineurium and perineurium 20%

Indications of cerebral ischemia in EP monitoring

50% decrease in amplitude 10% increase in latency

Is the combination of IA and IV agents additive or synergistic in depressing SSEP waveforms

Synergistic

Anesthetic rec for SSEP monitoring

Narcotic based TIVA <0.5 MAC Paralytics should not affect SSEP

Term for inequality of pupil diameter

Anisocoria

Neuromonitoring that is very resistant to interference

BAEP Brain stem-auditory

BIS

Bispectral index Analysis and processing of EEG signals with proprietary algorithm Numeric between 0-100 40-60 suggests general anesthesia

BIS less than 40 for more than 5 minutes

Increases postoperative mortality

Anesthetic concentrations on evoked potentials

Increased latency Decreased amplitude

Methemoglobinemia and SaO2

May cause falsely low reading when SaO2 is greater than 85% May cause falsely high reading if SaO2 is actually less than 85%

Failure of ETCO2 to return to zero

Incompetent expiratory valve (Or exhausted absorbent)

What does NIRS monitor?

Largely absorption of venous hemoglobin as it does not have ability to identify pulsatilla arterial component Saturations less than 40% or changes of 25% from baseline are problematic

Why is temperature management becoming a quality indicator for anesthesia? (What does hypothermia cause)

Hypothermia- delayed drug metabolism, hyperglycemia, vasoconstriction, impaired coagulation, increased risk of surgical site infections Hyperthermia- tachycardia, neurological injury, and vasodilation

Only time you might not use ETCO2

elective C section…

How often are you documenting HR and blood pressure?

Standard VIII as it applies to ventilators

Audible alarm with disconnect Low concentration alarm turned on and in use

What does SpO2 analyze?

PULSATILE flow

Pulse oximetry and wavelengths

660- absorbed by deoxyhemoglobin 940- absorbed by oxyhemoglobin

Plethysmographic function of SpO2

Differentiates arterial vs venous flow and gives us heart rate Variability can indicate fluid status

Spectrophotometric function of SpO2

Allows us to calculate SpO2 from pulsatile flow

ET vs FI

Expired vs Inspired concentration of gas…

Is ETCO2 typically higher or lower than PaCO2

Usually 2-5mmHg lower

What could cause a sudden increase in CO2

Administration of NaHCO3 Release of tourniquet Increase in pulmonary blood flow

Sudden decrease in ETCO2

Hypotension! Leakage Hyperventilation

Curare cleft Diaphragm, kicking back in

Rebreathing, think absorbent

Cardiac oscillations

COPD Asthma Other obstructions

Discuss dipole

Pair of charges moving together…. Positive before negative Movement toward positive=upward deflection

Isoelectric

Extinguishment of dipole, or a dipole at right angles to the positive electrode

Pathway of cardiac conduction

SA AV Bundle of HIS Bundle branches Purkinje Fibers

What leads do we commonly monitor and why?

II and V5 90% specific in detecting ischemia

What does lead II give us a view of?

Atria

Korotkoff sounds

Result from turbulent flow in an artery

Oscillometry

Basis of automatic BP cuffs

Sizing NIBP cuff

Bladder width 40% of extremity circumference Bladder length encircles > or = to 80% of extremity

False low readings of BP come from:

Large cuff Positioned above heart

False high readings of NIBP come from

Small cuff or loose cuff Extrinsic compression

2,3 DPG

Facilitates O2 transport via stabilization of deoxyhemoglobin, making it easier to release O2

Bigggg reimbursement measure in PACU

Temp>36

Most significant mechanism of heat loss in the OR

Radiation -transfer of heat to the environment

Best practice to prevent hypothermia

PRE- warming

When should we warm the OR?

Probably all the time Mainly in burn, pediatrics and elderly

Most common misuse of BIS monitoring

Need a baseline before you induce anesthesia

BIS awake

80-100

BIS moderate sedation

60-80

BIS general anesthesia

40-60

When will depth of anesthesia monitors not work?

Hypothermia Hypoglycemia Acid/base balance abnormalities Comorbid brain pathology

How much CO2 do we produce

200ml/min 12L/hr