Basic Intraop Monitoring Flashcards
What does early intervention lead to?
Improved outcomes
What does the data collected by the anesthetic provider reflect?
Physiologic homeostasis
Response to therapeutic interventions
Proper functioning of anesthetic equipment
What year did the AANA produce standards of care that CRNAs should adhere to?
1974 which it has evolved and revised over time
What year did Harvard produce guidelines for anesthesiologists?
1986, ASA closely mirrors those produced by the AANA
What year did the AANA revise the standards to include the scope of practice as well?
1983
What standard determines how a patient should be monitored by an anesthesia provider?
Standard V, monitor the patient’s physiologic condition as appropriate for the type of anesthesia and specific patient needs
What are the five monitors required by Standard V?
Monitor ventilation continuously
Monitor cardiovascular status continuously
Monitor body temperature continuously
Monitor neuromuscular function continuously
Monitor and assess patient positioning
What two factors are the basis of safe anesthetic care?
Continous clinical observation and vigilance
A state of clinical awareness whereby dangerous conditions are anticipated or recognized and promptly corrected
Vigilance in Anesthesia
What is the anesthetic provider continually monitoring?
Patient’s medical status
Effects of anesthesia
Effects of surgical intervention
What is the most important monitor?
The vigilant anesthetist
What are the AANA standard for monitoring?
Oxygenation/ventilation Circulation Body temperature Neuromuscular function Qualified Anesthetist Present
How should oxygenation be measured?
Clinical observation, pulse oximetry and if indicated arterial blood gas analysis
How should we verify intubation of the trachea?
Auscultation, chest excursion and confirmation of carbon dioxide in the expired gas
What should be used to measure ventilation?
Continuous monitoring of end tidal CO2 during controlled or assisted ventilation. Spirometry and ventilatory pressure monitors as indicated
What is the fundamental goal of the anesthetic provider?
Avoidance of hypoxia (airway, airway airway)
What should the anesthetic provider be assessing for adequate oxygenation?
Oxygen analyzer Pulse oximetry Skin color Color of blood ABG (when indicated)
What measures the pipeline gas to ensure O2 is truly being administered?
Oxygen analyzer
Where is the O2 analyzer located?
Inspiratory limb
When will the O2 analyzer notify the provider of low O2 concentrations?
less than 30% low concentration alarm
What two values should the O2 analyzer be calibrated to every day with the AGM check?
Room air and 100%
What is the Alveolar gas equations?
PAO2 = FiO2 x (Pb-47) - PaCO2
In the alveolar gas equation, if you do not have PaCO2 what value can be substituted?
End tidal CO2 can be substituted
What type of sensor is the O2 analyzer?
Electrochemical sensor
What is the structure of the electrochemical sensor of the O2 analyzer?
Cathode and anode embedded in electrolyte gel separated from gas by an oxygen permeable membrane
How does the electrochemical sensor in the O2 analyzer function?
O2 reacts with electrodes, generates electrical signal proportional to O2 pressure (mmHg) in sample gas
What is the standard of care for continuous non-invasive monitoring of oxygenation?
Pulse oximetry
What is a late sign of hypoxemia?
Cyanosis
When was the pulse oximeter introduced to anesthetic practice?
1987
What two principles are combined to explain the use of a pulse oximeter?
Oximetry & plethysmography
What is required in order to use a pulse oximeter?
Pulsatile arterial bed, a blood pressure must be present
What does plethysmography measure?
pulsatile measurement
What are some common sites to place a pulse oximeter?
Finger, toe, ear lobe, bridge of nose, palm and foot (especially in children)
What is the pulse oximeter continuously measuring?
Measurement of pulse rate and oxygen saturation of peripheral hemoglobin (SpO2)
What law dictate how a pulse oximeter works?
Lambert-Beer law of spectrophotometry
At what wavelength does HbO2 absorb light?
960nm (more infrared)
What does the Lambert-Beer Law of spectrophotometry measure?
Oxygenated and reduced Hgb differ in their absorption of red and infrared light
What is being compared in order to calculate an accurate SpO2 reading?
Comparison of absorbances of the wavelengths enables oximeter to calculate O2 saturation (ratio of infrared and red transmitted to a photodetector)
At what wavelength does reduced Hgb absorb more light?
660nm (more red)
What is the primary mechanism of action of the pulse oximeter?
Therefore, the basis of oximetry is change in light absorption during arterial pulsations
What does a patient’s Hgb have to be in order for a pulse oximeter to be functional?
> 5
What IV medication causes a large decrease in SpO2 while using a pulse oximeter?
Methylene blue
What are two other types of hemoglobins that could affect the pulse oximeter?
COHb (falsely increased)
MetHb (could be increased or decreased)
What is the correlation between SpO2 and PaO2?
40 50 60 PaO2
70 80 90 SpO2
Where should the precordial stethoscope be placed?
Suprasternal notch or apex left lung
What is the purpose of the precordial stethoscope?
Easily detects changes in breathe sounds or heart sounds
Circuit disconnect
Endobronchial intubation
What can be heard on the precordial stethoscope as anesthesia lightens?
Louder heart sounds from increased rate and contractility
What population can only use an esophageal stethoscope?
Limited to intubated patients
Where should the esophageal stethoscope be placed?
Distal 1/3 of esophagus
What are the advantage of an esophageal stethoscope compared to a precordial stethoscope?
Better quality heart and breath sounds and incorporates a temperature probe
How much CO2 does the average adult produce?
250mL CO2/min
What changes can affect a patient’s CO2 production?
Patient’s condition
Anesthetic depth (deeper decreases metabolism)
Temperature (colder decreases CO2 production)
What is the purpose of Capnography?
Confirms ETT placement Confirms adequate ventilation
What is the most common type of capnography and how does it work?
Sidestream sampling, airway gas aspirated and pumped to measuring device
What are the sampling flow rate?
50-250mL/min pulled from circuit (be aware in peds patients)
What are some limitations to sidestream capnography?
H2O condensation can contaminate the system and falsely elevate readings
Lag time between sample aspiration and reading
How might an attached capnography affects a machine check?
May fail a machine check if sidestream sampling line attached, specifically the pressure check
What could a problem be if CO2 is detected on inspiration?
Incompetent inspiratory valve
What is the normal PACO2-PaCO2 gradient?
2-10mmHg
What does phase I on a capnograph represent?
Corresponds to inspiration, anatomic/apparatus dead space devoid of CO2
What should the phase I level be at?
Should be zero unless rebreathing
What would cause baseline elevation on a capnograph?
CO2 absorbant exhaustedExpiratory valve missing/incompetentBain circuit
What does phase II of a capnograph represent?
Early exhalation/steep upstroke, mixing of dead space with alveolar gas
What would cause a prolonged upstroke of phase I on a capnograph?
Mechanical obstruction (kinked ETT) Slow emptying of lungs (COPD and bronchospasm)
What does phase III on the capnograph represent?
CO2 rich alveolar air, horizontal with mild upslope
Why would phase III on a capnograph be steep?
Steepness is a function of expiratory resistanceCOPDBronchospasm
What does phase IV on a capnograph represent?
Inspiration of fresh gas, return to baseline (near 0)
What might a low plateau on a capnogram represent?
Excessive ventilation
Low CO2 production
Diminished CO2
Significant dead space
What might a high plateau on a capnogram represent?
Hypoventilation
High CO2 production (MH)
What might a flat plateau with wide dips represent on a capnogram?
Less TV are superimposed on normal or mechanically timed exhalations, common when NMBA begin to wear off