Monitors Flashcards
(38 cards)
How must we measure oxygenation (3)
- FiO2 analyzer
- Low [O2] alarm
- Pulse ox w/ variable pitch tone
How must we measure ventilation (2)
- Continuous capnography
- Disconnect alarm for vent
How must we measure circulation (3)
- EKG (3 or 5 leads)
- Blood pressure q5m
- ONE continuous measurement (pulse ox, a line, palpable pulse, auscultation, doppler)
When must we monitor temp
If significant changes are anticipated
How does pulse ox determine oxygenation?
- Light emitted at 660 (red, Hb) and 940 (infrared, HbO2) -> measures light absorbed
- Absorption during DC flow (non-pulsatile) is removed (aka venous, capillary, tissue flow)
How is SpO2 calculated?
S value = (AC/DC 660)/(AC/DC 940)
Why is a pulse ox not on a patient 85%?
1:1 ratio S value = 85%
Methemoglobin - how does SpO2 read?
- Approaches 85% (similar absorption at both wavelengths)
- Will appear falsely low if it’s actually > 85
- Will appear falsely high if it’s actually < 85
Carboxyhemoglobin - how does SpO2 read?
Falsely high (reads similar to HbO2)
What causes falsely low SpO2? (6)
- blue/green dyes
- blue nail polish
- shivering/motion
- ambient light
- low perfusion (low CO, anemia, hypothermia, etc)
- Mal-positioned sensor
SaO2 vs SpO2
SaO2 = HbO2 / ALL Hb
SpO2 = HbO2/(Hb + HbO2)
Things that DON’T affect SpO2
- Bilirubin
- HbF/HbS/SuHb
- acrylic nails
- flourescein dye (yellow-green)
When is cyanosis clinically seen?
With 5 g/dl desaturated Hb
- At Hb 15 -> 80% SpO2
- At Hb 9 -> 66% SpO2
Best lead for P waves and sinus rhythm
II
How to monitor for anterior ischemia w/ 3-lead EKG
Move L arm to V5 position, monitor lead I
Where does V5 lead go?
L anterior axillary line, 5th ICS
5-lead EKG - what can be monitored?
7 simultaneous leads
5-lead EKG - how to detect ischemia? (3) (least-most sensitive)
- V5 = 75%
- II + V5 = 80%
- II + V4 + V5 = 98%
How does NIBP work?
Measures oscillations in blood flow across different cuff pressures
– loudest oscillation pressure = MAP
Indications for invasive BP monitor (5)o a
- Moment-to-moment BP changes
- Planned pharm or mechanical manipulation
- Repeated blood sampling
- Failure of NIBP
- Measure volume status (via pulse pressure)
How does SBP and MAP change in aorta vs peripheral?
- SBP higher in periphery 2/2 reflected waves
- MAP is unchanged b/c higher SBP is offset by more time at diastolic pressure (“narrowing of systolic pressure wave”)
How does BP change based on vertical height?
pH = 7.410
Change in pressure (p) of 7.4 mmHg for every 10cm of height (H) difference
Up-sloping end tidal trace
Bronchospasm
Significant hypotension can lead to a ___ in EtCO2
Decrease
