Vitals Monitoring (Stanford) Flashcards
What is your differential for a Drop in ETCO2
- decreased CO2 elimination
- acute cardiovascular collpase
- massive PE
- venous air embolism
- kinged or dislodged or esophageal ETT - decreased CO2 production
- hypothermia
- hypothyroid
- NMB - circuit samplerdisconnected
What rate does ETCO2 rise during apnea?
increases by 6 mmHg after first minute and by additional 3 each minute after
Capnography curve meanings:
- upsloping curve
- Sudden drop
- decreased ETCO2, increased A-a gradient of ETCO2 and PaCO2
- During cardiac arrest, return of ETCo2 and ETCO2>10
- No ETCO2
- ETCO2 does not return to baseline 0-5
- bronchospasm or obstructive lung disease
- significant hypotension
- PE
- ROSC and good compressions
- circuit disconnect or esophageal intubation
- desiccated CO2 absorbent
What are the 4 parts of a capnography curve?
- Deadspace air ventilated
- transition to alveolar air
- alveolar air plateau
- inspiration
Factors affecting pulse pressure variation? What can it be used for and when?
Pulse pressure is increased when stroke volume increases and when vessel wall compliance decreases
Increased pulse pressure variation can be used to influence fluid administration in a patient that is supine, in sinus rhythm, and mechanically ventilated. Pulse pressure variation > 15% suggests responsiveness to fluids
In mechanical ventilation, positive pressure during inspiration will increase pulse pressure
In spontaneously breathing patients, negative inspiratory pressure during inhalation will decrease pulse pressure
What is the 5 electrode EKG and what are the advantages?
5 electrode EKG consists of 4 limb electrodes and a chest V electrode (can be anywhere V1-V6) comprising of 7 total leads
More sensitive for detecting ischemia depending on V chest electrode placement
V1: better atrial detection
V4: anterior ischemic event
V5: 75% sensitive for ischemic event (lateral)
II + V5: 80% sensitive for ischemic events
II + V4 + V5: 98% sensitive (add additional electrode)
What is the modified 3 electrode EKG and what can it monitor?
Move the LA electrode to the V5 position (left mid clavicular line at the 5th rib)
RA and LA electrodes comprise Lead I and the new lead I position can be used as a sensitive monitor for ischemia
In normal 3 electrode EKG what electrodes compose lead II and what does this measure?
RA and LL leads comprise lead II
Lead II is sensitive for atrial dysrhythmias and p wave formation
Poor detection of ST changes (without modified placement)
effect of arterial line distance on BP tracing patterns
further distance from proximal aorta causes the systolic amplification from reflected waves which shows as narrowed and peaked systolic waves with later dichrotic notch, however MAP remains unchanged regardless of distance
normal waveform of arterial tracing has a systolic peak with a smaller dichrotic notch
effects of position on BP readings
For NIBP, limb positioning will alter blood pressure readings (ie lifting arm vs resting)
<mnemonic: pH = “7.410”>
For every 10cm of elevation decreases both SBP and DBP by 7.4 mm Hg
For arterial line monitoring, typically, the transducer is leveled at the Right atrium but can change level to anything ie track MAP of brain (but this is not CPP or ICP), in this case repositioning of catheter insertion point will not affect BP as long as transducer remains in place
equations (3) for MAP
MAP = (SBP+ 2(DBP))/3
or
MAP = DBP + (1/3) x pulse pressure
Pulse pressure = SBP-DBP
or
MAP = CO x SVR
effects of cuff size on BP accuracy
too tight = falsely high
too loose = falsely low
Major mechanisms of heat loss during general anesthesia in OR
- Redistribution (vasodilation causing blood shift from core to periphery)
- Radiation (ie exposure)
- conduction, convection, evaporation
How can you titrate gas to manage temperature in OR
low fresh gas (ie cold gas) utilization will prevent body heat loss and water loss
Accurate vs Inaccurate Temperature monitoring
“Gold standard” core temp:
- pulmonary artery catheter (invasive)
Accurate correlates with core temp:
- tympanic membrane
- nasopharyngeal (caution epistaxis in coagulopathies)
- oropharynx
- esophagus (caution esophageal varices)
- bladder (best when urine flow is high)
Inaccurate:
- skin (based on skin perfusion)
- axillary (varies by site)
- rectal (stool insulation, LE venous return, enteric organisms)
Clinical cyanosis presents at approx what SpO2
SpO2 85% or 5g/dl of desaturated Hb
Causes for falsely low pulse ox reading
malpositioned sensor
motion
ambient light
blue nail polish
low perfusion (CO failure, inc SVR, hypothermia, anemia)
dyes
- methylene blue (treatment for met-Hb)
- indocyanine (contrast for angiography)
- indigo carmine (dye for cystoscopy)
Causes of Cyanide poisoning?
Treatment?
Causes:
- nitroprusside (direct vasodilator)
- smoke inhalation
Treatment:
-hydroxycobalamin (vitamin B12)
Cyanide poisoning effects on pulse ox accuracy
Cyanide disrupts the oxidative phosphorylation in the electron transport chain, disabling cellular use of oxygen.
Pulse ox will be high correctly measuring O2Hb BUT cells cannot utilize oxygen (therefore the pulse ox is falsely depicting appropriate clinical oxygenation!)
PaO2 value of ABG will be similar to that of VBG since circulating O2-Hb remains unused by the tissues
Lactate serum will be elevated due to anaerobic metabolism and representing low oxygenation of tissues
Cyanide poisoning effects on pulse ox accuracy
Cyanide disrupts the oxidative phosphorylation in the electron transport chain, disabling cellular use of oxygen.
Pulse ox will be high correctly measuring O2Hb BUT cells cannot utilize oxygen (therefore the pulse ox is falsely depicting appropriate clinical oxygenation!)
PaO2 value of ABG will be similar to that of VBG since circulating O2-Hb remains unused by the tissues
Lactate serum will be elevated due to anaerobic metabolism and representing low oxygenation of tissues
Causes of CO-Hb?
Treatment?
Causes:
- smoke inhalation
- volatile anesthetic degradation
- dessicated baralyme/sodalime (CO2 absorbant)
baralyme = Calcium hydroxide
sodalime = Na hydroxide
Treatment:
100% FiO2
hyperbaric oxygenation
Effects of CO-Hb on pulse ox accuracy
CO-Hb has similar absorbance to O2-Hb but CO has a higher affinity than O2 to bind to Hb and will cause a falsely elevated SpO2.
In the setting of CO-Hb, SaO2 can be 50% on ABG but the SpO2 will falsely be elevated at 95%.
Causes of Met-Hb?
Treatment?
causes include:
- benzocaine topicalization spray (local anesthetic)
- metoclopramide (Reglan, antiemetic, antidiarrheal)
- dapsone (antibacterial for leprosy/acne/herpes)
- nitric oxide (ie inhalation for pHTN)
- nitroglycerine (for angina)
Treatment:
- methylene blue
effects of Met-Hb on pulse ox accuracy
Met-Hb has similar light absorption at both 660nm and 940 nm and as serum levels rise SpO2 will deviate towards 85% relative to the true SaO2.
examples:
1. PaO2 can be normal with a correct SaO2 of >85% but the SpO2 will be incorrectly low (moving towards 85%)
2. if true SaO2 is <85%, the SpO2 reading will be falsely elevated towards 85%
absorption wave length of:
- Hb
- O2Hb
Hb: 660nm (red)
O2Hb: 940nm (infrared)
Fractional oximetry equation
vs
Functional oximetry equation
Fractional oximetry (central/true):
SaO2 = O2Hb/(O2Hb +Hb + metHb + COHb)
Functional oximetry (aka pulse ox):
SpO2 = O2hb/(O2Hb + Hb)
continual vs continuous
continual: cycled routinely (i.e. q5min)
continuous: without interruption (i.e. arterial line/EKG)
ASA standard 2: “___”
“During all anesthetics, the patient’s oxygenation, ventilation, circulation and temperature will be continually monitored”
Examples:
Oxygenation - Pulse ox (w/ variable pitch tone), FiO2 analyzer + low oxygen alarm
Ventilation - ETCO2 (capnography)
Circulation - BP/art-line (cycled minimum q5min/continuous), EKG (minimum 3leads, 5lead for cardiac concerns)
Temperature - NP temp probe
ASA standard 2: “___”
“During all anesthetics, the patient’s oxygenation, ventilation, circulation and temperature will be continually monitored”
Examples:
Oxygenation - Pulse ox (w/ variable pitch tone), FiO2 analyzer + low oxygen alarm
Ventilation - ETCO2 (capnography)
Circulation - BP/art-line (cycled minimum q5min/continuous), EKG (minimum 3leads, 5lead for cardiac concerns)
Temperature - NP temp probe
ASA standard 2: “___”
“During all anesthetics, the patient’s oxygenation, ventilation, circulation and temperature will be continually monitored”
Examples:
Oxygenation - Pulse ox (w/ variable pitch tone), FiO2 analyzer + low oxygen alarm
Ventilation - ETCO2 (capnography)
Circulation - BP/art-line (cycled minimum q5min/continuous), EKG (minimum 3leads, 5lead for cardiac concerns)
Temperature - NP temp probe
ASA standard 1: “___”
“Qualified anesthesia personnel shall be present in the room throughout the conduct of all general anesthesia, regional anesthesia, or monitored anesthesia care”
ASA standard 1: “___”
“Qualified anesthesia personnel shall be present in the room throughout the conduct of all general anesthesia, regional anesthesia, or monitored anesthesia care”
