Principles of the Anesthesia Machine Part 2 Flashcards
An anesthetist is running 6L/min Air, 3L/min N2O, and 1L/min O2. What is the FiO2?
22.6%
An anesthetist is running 3L/min of air and 0.5L/min of oxygen. What is the patient’s FiO2?
32.3%
What is vapor pressure?
the pressure a vapor exerts above the liquid in a closed container
What is latent heat of vaporization?
when the liquid evaporates it loses heat (gets cold)
What is the vaporizer dial?
It determines the concentration of the agent that is delivered to patient
An anesthetist is delivering straight Air and 6% Desflurane to a patient. What is the patient’s FiO2?
19.74%
An anesthetist is delivering 1L/min O2, 1L/min N2O, and 2% Sevoflurane. What is the FiO2?
49%
What is variable bypass?
some of the FGF gases bypass the vaporizer
What volatile agents have variable bypass?
Isoflurane and Sevoflurane
What volatile agent doesn’t have variable bypass? What happens instead?
Desflurane; a percentage of Des joins the FGF gases
What is special about Desfluranes vaporizer?
It is pressurized and heated; Des has a high vapor pressure and would lose heat and it’s ability to vaporize without this special vaporizer
What are the volatile agent safety features?
1-color
2-safety interlock system (one on at a time)
3- keyed filler adapter (only can put it in correct vaporizer)
How does the machine control pressure in vent mode?
The ventilator has its own APL valve, relieves pressure at the end of expiration
What could a leak in the bellows of the ventilator lead to (2)?
1- higher than expected PIP
2- Higher than expected FiO2
Would you prefer your ventilator to have descending (hanging) bellows or ascending (standing) bellows? Why?
Ascending bellows because you can better diagnose a leak in the bellow. (No gravity to help open it up)
What is compliance?
The ability of a container to expand when pressure is added to it. (old balloon [high] vs. new balloon[low])
What are the units of pulmonary compliance?
mL/cmH2O
What is the equation for pulmonary compliance?
change in volume (mL)/change in pressure (cmH2O)
What is pulmonary elastic recoil (elasticity)?
the ability of a container to return to the original volume after the pressure has been released
Fill in the blank:
High compliance means _____ elasticity.
low
What type of patients would have high compliance?
COPD patients, smokers (easy inhale, hard exhale)
What type of patients would have low compliance?
acute respiratory distress syndrome (hard inhale, easy exhale)
A patient’s pulmonary compliance is 20mL/cmH2O. They are being ventilated with positive pressure ventilation (PPV) on a ventilator with 30cm/H2O pressure. What is the patient’s tidal volume?
600mL
A patient on a ventilator is receiving a tidal volume of 600 mL. The inspiratory pressure waveform is shown. What is the patient’s dynamic lung compliance in mL/cmH2O?
30mL/cmH2O
What are the 5 common ventilator settings?
1- Tidal volume (Vt) 2- Respiratory Rate (RR) 3- Inspiratory:Expiratory Ratio (I:E) 4- Peak Inspiratory Pressure (PIP) 5- Positive End Expiratory Pressure (PEEP)
What is a normal Vt?
5-10L/min
What is a normal RR for vent mode?
8-12
What is a normal I:E?
1:2 (smokers/COPD= 1:2.5)
What is a normal PIP?
35-40cm/H2O for ETT
What is a normal PEEP?
~5cm/H2O (if used)
Why use PEEP?
To keep a small volume in the lungs after expiration to keep alveoli open and prevent atelectasis.