Exam 1- Clinical Monitoring (6/8/23) Flashcards
AANA Monitoring Standards for Oxygenation
- Clinical Observation (watch your patient)
- Continuous Pulse Oximetry
- ABG’s as indicated
AANA Monitoring Standards for Ventilation
- Auscultation
- Chest excursion (rise/fall of chest)
- ETCO2 documentation
- Pressure monitors as indicated
- Monitor RR q 5 mins
AANA Monitoring Standards for Cardiovascular System
- Electrocardiogram
- Auscultation as needed
- BP and HR documentation q 5 mins
AANA Monitoring Standards for Thermoregulation
- When clinically significant changes in body temp are anticipated or suspected
- Continuous monitor of temperature in cases longer than 20 minutes, pediatric cases, or elderly patients.
AANA Monitoring Standards for Neuromuscular System
- When neuromuscular blocking agents are administered.
- TOF are charted q 15 mins
Name factors that will cause the Hb dissociation curve to shift right.
Name factors that will cause the Hb dissociation curve to shift left
Remember:
Right shift = ↓ Hb affinity to O2.
Left shift = ↑ Hb affinity to O2
How low can a healthy normal adult patient’s PaO2 decrease before their O2 saturation drops below 90%?
PaO2 can decrease to 60 mmHg before O2 saturation drops below 90%.
Upon what law of physics is pulse oximetry based?
- Beer-Lambert Law
Explain how concentration of a solute affects light absorption in pulse oximetry.
- Amount of light absorbed is proportional to the concentration of the light absorbing substance (Beer’s Law)
- Higher Hb concentration, more light absorption
Explain how distance affect light absorption in pulse oximetry.
- Amount of light absorbed is proportional to the length of the path that the light has to travel in the absorbing substance (Lambert’s Law)
- Wider arteries, more light absorption
What were the four species of Hb in adult blood discussed in lecture?
- Oxyhemoglobin (O2Hb)
- Deoxyhemoglobin (deO2Hb)
- Methemoglobin (metHb)
- Carboxyhemoglobin (COHb)
What is considered the gold standard for SaO2 measurements and is relied on when pulse oximetry readings are inaccurate or unobtainable?
- CO-oximetry
4 wave lengths
The wavelength of red light
- 660 nm
The wavelength of infrared light
- 940 nm
__________ absorbs more infrared light.
___________ absorbs more red light.
Choose between oxyhemoglobin and deoxyhemoglobin
SeXy DARLing:
SiX hundred wavelength, DeoxyHb Absorbs Red Light.
How does the amount of oxyhemoglobin and deoxyhemoglobin in the blood affect oxygen saturation?
- As the amount of oxy Hb and deoxy Hb changes, the light ratio comparing red and infrared light also changes.
- The pulse oximeter uses the ratio to work out the oxygen saturation.
- More DeoxyHb present, ↑ Red Light: Infrared Light Absorption Ratio, ↓ O2 sat
Which Hb species absorbs as much light in the 660 nm range as OxyHb?
- Carboxyhemoglobin
The absorption of light at 660 nm by COHb is similar to that of O2Hb. At 940 nm, COHb absorbs virtually no light. Thus, in a patient with carbon monoxide poisoning, the SpO2 will be falsely elevated.
Each 1% increase in COHb will increase SpO2 by _____%.
- 1%
Many smokers have > ______% of COHb.
- 6%
Schematic of the Pulse Principle.
- Light absorption through tissue is characterized by a pulsatile component (AC) and a non-pulsatile component (DC).
- The pulsatile component of absorption is due to arterial blood. The non-pulsatile component is due to venous blood and the remainder of the tissues.
What factors cause signal artifacts in pulse oximetry?
- Ambient light
- Low perfusion
- Venous blood pulsations
- Additional light absorbers (methylene blue)
- Additional forms of Hb
- Nail polish
How accurate is pulse oximetry when measured against ABGs as long as the patient’s O2 saturation is >70%?
- Pulse oximetry’s accuracy is within 2% of an ABG.
List advantages of pulse oximetry. (Long list, common sense)
- Accurate/ Convenient
- Not affected by anesthetic vapors
- Noninvasive
- Continuous
- May indicate decreased cardiac output
- Tone modulation
- Probe variety (Ear probe)
- Battery-operated/ Cheap
List disadvantages of pulse oximetry. (Long list, common sense)
- Poor function with poor perfusion
- Delayed hypoxic event detection
- Erratic performance with dysrhythmias
- Inaccuracy with different hemoglobin (COHb)
- Inaccuracy with dyes
- Optical interference
- Nail polish and coverings
- Motion artifact
Fingers are relatively sensitive to ________
- vasoconstriction
What kind of nails inhibit pulse oximeter transmission?
- Dark polish or synthetic nails
True/False: Pulse Oximetry detection of desaturation and resaturation from the periphery is slow.
- True
Why shouldn’t the pulse oximeter be placed on the index finger?
- ↑ risk of corneal abrasion
Where will you place a pulse oximeter for the most accurate reading during an epidural block?
- Toes
Toes will be more dilated than fingers with an epidural block.
What three parts of the body are least affected by vasoconstriction and will reflect desaturation quickly?
- Tongue
- Cheek
- Forehead
Most indirect methods of blood pressure measurement utilize a sphygmomanometer. What is the series of audible frequencies produced by turbulent flow beyond the partially occluded cuff called?
- Korotkoff sounds
Describe the phases of the Korotkoff sounds.
During what phase will you hear SBP and DBP?
- Phase I: the most turbulent/audible (SBP)
- Phase II: softer and longer sounds
- Phase III: crisper and louder sounds
- Phase IV: softer and muffled sounds
- Phase V: sounds disappear (DBP)
Give the formula to calculate MAP
- MAP = DBP + 1/3 (SBP - DBP)
What factors will limit BP auscultation?
- Decrease peripheral flow (shock/vasoconstriction)
- Changes in vessel compliance (atherosclerosis)
- Incorrect cuff size
- Obesity
What is the best way to measure BP in pediatric patients?
- Use the automatic NIBP