Oxygenation And Ventilation Flashcards
How is oxygenation measured??
Pulse oximeter or blood gas
A patient is hypoxemic if PaO2
60mmHg; 90%
A healthy animal breathing air should have a SaO2 of ??
> 95%
A healthy animal breathing 100% O2 should have a SaO2 of ??
100%
Pulse oximeter are inaccurate and can show 98-99% even if real saturation is 100%
How does a pulse oximeter work?
Pulse oximeter emits read and infrared light on one side of tissue and measures on the other
Red and infrared light are absorbed differently by oxygenated and reduced Hb
—> differences are used to calculated oxygen saturation
What factors can alter the pulse oximeter measurement?
Tissue thickness Hypo perfusion (vasoconstriction) Anemia, pigmentation Movement Abnormal Hb sp (CO or methemoglobinemia)
When should we use a pulse oximeter?
Patient is breathing air
V/Q mismatch
Respiratory disease
-less important for healthy animals intubated with 100% O2
What is a normal PaCO2?
35-45mmHg
What other things do we evaluate besides PCO2 when assessing a patients ventilation status?
Normal tidal volume?
Respiratory rate
Rhythm
Effort
If PaCO2 is > 45mmHg the animal is?
Hypercapnic, or hypoventilation
If an animal has PaCO2 of 35-45mmHg then it is…?
Normocapnic or normoventilation
If an animal has PaCO2 <35mmHg, it is …?
Hypocapnia or hyperventilation
How can you assess respiratory rate?
Auscultation the thorax
Observed movement of thorax and abdomen
Movement of breathing bag
Capnograph
How can you asses the tidal volume of a patient?
Spirometer
Observe scale of ventilator bellows
Why do we monitor BP in patients under anesthesia??
Indicator of tissue PERFUSION!
What is capnometry?
Measurement of CO2 partial pressure in the airways
How can you determine if your capnograph is valid?
Assess airway integrity Assess equipment (ventilator, breathing circuit, and gas sampling) Verify proper ET tube
What factors can change CO2 values?
CO2 production (pain/hyperthermia/MH)
Circulation
Alveolar ventilation
Measurement error
The lowest point of a capnograph waveform is what?
Inspiration
The slope from the lowest to highest point on a capnograph indicates?
Expiration
The highest plateau on the capnogram indicates
Alveolar plateau
A small short capnograph indicates?
Hyperventilation
Capnograph with high and wide waveforms inicates??
Hypoventilation
If a patient is CO2 rebreathing, what would the capnograph look like?
You would start to see a rise in the waves
-> could be due to expired soda-line, sticking one way valves, or low fresh gas flow in non-rebreathing system
