Anesthesia Monitoring Flashcards
Why do we monitor patients?
- one of the standards of care
- assess data indicating - patient status, patient’s response to therapeutic interventions, anesthesia equipment functionality
Standard 9
- monitor, evaluate, and document
- alarms on and audible
documentation requirements
- at least every 5 min
- BP
- HR
- RR
alarms in anesthesia
- reflect changes in patient or equipment status
- variable pitch
- threshold alarms on and audible
vigilance
state of clinical awareness whereby dangerous conditions are anticipated or recognized and promptly corrected
Standard 9 Required Monitors
- oxygenation
- ventilation
- cardiovascular
- thermoregulation
- neuromuscular function
Standard 9 oxygenation
continuously monitor oxygenation by clinical observation and pulse oximetry; team communicates and collaborates to mitigate risk of fire
Standard 9 ventilation
- continuously monitor ventilation by clinical observation and confirmation of continuous ETCO2 during moderate sedation, deep sedation, or general anesthesia
- verify intubation of trachea or placement of other artificial airway device by auscultation, chest excursion, and confirmation of expired CO2
oxygenation measurement tools
- oxygen analyzer
- pulse oximetry
- skin color
- color of blood
- ABG (when indicated)
oxygen analyzer facts
- measures FiO2 - inspired gas from inspiratory limb
- low concentration alarm if <30% from pipeline
- calibrate to RA and 100%
- required for any general anesthetic
- useful for calculating PaO2 with alveolar gas equation
oxygen analyzer
electrochemical sensor, cathode and anode embedded in electrolyte gel separated from oxygen gas by oxygen permeable membrane; O2 reacts with electrodes, generates electrical signal proportional to O2 pressure (mmHg) in sample gas
pulse oximetry
- standard of care for continuous oxygen monitoring
- early warning for hypoxemia
- requires pulsatile arterial bed
- finger, toe, ear lobe, bridge of nose, palm and foot in children
- continuous measurement of pulse rate and oxygen saturation of peripheral Hgb (SpO2)
mechanism of pulse oximetry
- beer-lambert law
- oxygenated Hgb absorbs more infrared light (960 nm)
- deoxygenated Hgb absorbs more red light (660 nm)
- oximeter calculates O2 saturation –> ratio of infrared and red transmitted to a photodetector; comparison of absorbances of these wavelengths
- basis of oximetry is change in light absorption during arterial pulsation (pulsation –> increased path length)
factors affecting pulse oximetry accuracy
- high intensity light
- patient movement
- electrocautery
- peripheral vasoconstriction
- hypothermia
- cardiopulmonary bypass
- presence of other Hgb (COHgb –> false high reading; MetHgb –> false low or high)
- IV injected dyes (methylene blue)
- hemoglobin < 5 (will not register)
Hypoxia
SaO2 less than 90%
what is ventilation
- movement of volume, inhalation/exhalation
- elimination of CO2
ventilation monitors
- continuous auscultation
- chest excursion (observation)
- end-tidal capnography
- spirometry
precordial stethoscope
- position at suprasternal notch or apex of left lung (where heart/lung sounds audible)
- easily detect changes in breath or heart sounds
- airway/circuit disconnect
- endobronchial intubation
- anesthetic depth/increase HR or contractility
esophageal stethoscope
- soft plastic catheter
- balloon covered distal openings
- limited to intubated patients
- better quality heart and breath sounds
- incorporated temperature probe
- place through mouth or nose into esophagus (distal 1/3), to provide core temperature
esophageal stethoscope contraindications
esophageal varices or strictures
respiratory gas analysis
- gas sampling line (CO2, O2, volatile anesthetics)
- allows measurement of volatile anesthetics
- non-dispersive infrared (NDIR) most common
NDIR
- side stream sampling (continuous gas aspiration)
- gas absorbs infrared energy at specific wavelength (sp to each gas)
- complex algorithm and microprocessor
- multiple narrow band optical filters through which infrared emission passed to determine which gas is present in that mixture
dispersive infrared gas analysis
prism or diffraction grading mechanism to separate component wavelengths for each of our agents
how much CO2 does the average adult produce
250 mL/min