Exam 3 - Lecture 6 Flashcards
If starting at FRC, we take a VT breath, what is our new alveolar volume?
3.350 L
(3L + 350mL of alveolar air)
PAO2 fluctuates depending on where in the ____
respiratory cycle we are
Going to be higher during inspiration, lower the longer we get away from inspiration.
If we have a PAO2 of 100mmHg at the end of inspiration, how many mL of air is oxygen in the lungs?
100/760 –> 13.16% O2
(.1316) x (3.350L) = 0.395 L
Of the 0.395L of oxygen in the lungs at end of tidal volume, how much is used per minute? how does that equate to length of breath holding?
The body only uses 250mL/min, so that is why we can hold our breath from 1.5 - 2 minutes, because we have more than 250mL of oxygen in there.
A 30-year-old healthy man is scheduled for elective surgery. He is preoxygenated with 100% oxygen before induction of anesthesia. At baseline, he is upright, breathing room air, and at rest. His functional residual capacity (FRC) is approximately 3.0 L, and his pulmonary venous PO₂ is 100 mmHg.
Which of the following best approximates the volume of oxygen available in the lungs at the end of a normal expiration?
A) 210 mL
B) 315 mL
C) 395 mL
D) 440 mL
E) 525 mL
C
100/760 = .1316
.1316 x 3L = .395L
.395L = 395mL
this is the correct amount for end of a normal EXPIRATION
The previous example from class included alveolar volume of 350mL because it was at the end of INSPIRATION.
A 65-year-old man is undergoing general anesthesia for abdominal surgery. He is preoxygenated with 100% FiO₂ while in the supine position. His functional residual capacity (FRC) is reduced to 2.4 L due to body habitus and position. After preoxygenation, the PAO₂ reaches 663 mmHg. His tidal volume is 500 mL, of which 150 mL is anatomical dead space.
Assuming complete mixing and equilibration, what is the best estimate of the total volume of oxygen in the lungs at the end of inspiration?
2.4L + .35L = 2.75L
663/760 = ~.87
.87 x 2.75L = 2.399L or 2399mL
A patient has a hemoglobin of 10 g/dL, SaO₂ of 88%, and PaO₂ of 60 mmHg. What is their total arterial oxygen content?
11.972mL O2/dL
ABG shows a PaO₂ of 55 mmHg. Hemoglobin is 11.5 g/dL, and total arterial oxygen content is estimated to be 11.5 mL O₂/dL.
What is the arterial oxygen saturation?
55 x .003 = 0.165mL/O2/dL
11.5 - 0.165 = 11.335mL/o2/dL is BOUND
if that’s how much is how bound, and their Hb is 11.5
(11.5) x (1.34) x (?) = 11.335mL/O2/dL
To finish, 11.5 x 1.34 = 15.41
11.335 divided by 15.41 = .7355
Final answer = ~73.6%
What’s the arterial sat?
Hb = 14.2g/dL
PaO2 = 51mmHg
Total arterial oxygen content = 13.7mL/O2/dL
51 x .003 = 0.153
13.7 - 0.153 = 13.547
14.2 x 1.34 = 19.028
13.547 / 19.028 = 71.2%
Fresh inspired air should dilute the CO2 in the lungs by a factor of _____
4 mmHg
When PAO2 is 100mmHg, the O2 concentration is
13.16%
100/760 = .1316
The right lung is _____, ______, and has __________ than the left lung.
heavier, larger, and has more volume
Left lung is taller or shorter than the right lung, and why?
Taller. Heart sitting on central tendon of diaphragm causes it to depress lower than right lung.
Pleura on lung itself
visceral pleura
Pleura on inside of chest wall is
parietal pleura
What are the 2 fissures on right lung?
Horizontal and oblique fissure
Horizontal separates superior and middle lobe
Oblique separates middle and inferior lobe (at a goofy angle and off-kilter)
How many segments does the right lung have?
Left?
10; 8
What is a potential space?
Pleural space
What is the space between the top of the diaphragm and side of ribcage called?
Costodiaphragmatic recess
If we had any air or vacuum in the diaphragm, where would it be?
Costodiaphragmatic recess
where does the diaphragm bind to?
L1/Base of thorax at vertebral spinous processes
How many scalene muscles are there?
6 total; 3 on each side.
What muscles are used to take a deep inspiration?
obviously diaphragm, then scalene muscles and exterior intercostal muscles
What do the anterior scalene muscles bind to?
C3-C6
