ventilation dynamics

Question 1

respiratory rate

Answer 1

calculation is Vm/Vt
or 60/TCT
number of breaths in one min

Question 2

Vt (tidal volume)

Answer 2

formula
Vt=Vm/RR or Vt=V x Ti
can be expressed in L or mL
volumes of gas inhaled and exhaled during a normal breath

Question 3

Vm ( minute ventilation)

Answer 3

total amount of gas inhaled and exhaled in one minute
Vm= RR x Vt
can be expressed in L or mL over a min !

Question 4

V ( flow) dynamic

Answer 4

during inspiration diaphragm pushes down, external intercostal contracts, thoracic cavity expands. exhalation diaphragm goes up and thoracic cavity reduces, external intercostal relax.

Question 5

v flow

Answer 5

V= Vt / Ti
expressed in mL/sec or L/min
speed of gas traveling through the airways.
Function of VT and Ti

Question 6

TCT (total cycle time)

Answer 6

beginning of inspiration and end of exhalation
TCT= Ti +Te
TCT= 60sec /RR
expressed in sec or min

Question 7

Ti ( inspiratory time)

Answer 7

length of inspiration (beginning of inspiration to end of inspiration)
Ti= TCT-Te
Ti= Vt/V
express in secs

Question 8

Te (expiratory time)

Answer 8

length of expiration period (from beginning of expiration to end of exp.)
Te= TCT-Ti
expressed in sec

Question 9

I:E ration

Answer 9

comparison of Ti and Te
(Ti/Ti) : (Te/Ti)
Ti is always one the only variable is Te

Question 10

Driving pressure

Answer 10

pressure gradience (difference) that exist btw two areas.

Question 11

Intrapulmonary pressure ( Palv)

Answer 11

alveolar pressure
pressure within the lungs
760mmHg (0mmHg) at rest

Question 12

Transaiway pressure (pta)

Answer 12

pressure gradient that exists btw the mouth/ pahrynx and alveoli
Pta= Ptm- Palv

Question 13

intrapleural pressure (Ppl)

Answer 13

usually neg ( makes lung want to shrink or collapse)
pressure within the pleura space
756 mmHg at rest (-4mmHg)

Question 14

transpulmonary pressure

Answer 14

distending pressure (pressure distance btw alveolar and pleural space)
Ptp= Palv-Ppl)

Question 15

pressures during inspiration

Answer 15

Diaphragm contracts, moves downward, Thorax expands
Intrapleural (Ppl) and intra-alveolar (Palv) P Down: Alveolar Vol up
At this pt, intra-alveolar P is less than barometric P, gas moves into the lungs
Continues until equilibrium between barometric and P alv = end inspiration
Diaphragm stops downward movement

Question 16

pressure during exhalation

Answer 16

Diaphragm and thorax relaxes
Thoracic Volume   in Ppl and Palv
Palv becomes > than barometric P (PB)
Note: diaphragm continues to move upwards
Gas flows out of the lungs and Alveolar volume 
This continues until Palv and PB reach equilibrium = end expiration
Ppl remains at resting level
Ppl regardless of the breathing cycle is always less than PB

Question 17

PIP peak inspiratory pressure

Answer 17

pressure right at the beginning of air flow. (oral cavity)

Question 18

Plateau pressure

Answer 18

pressure that’s in the lungs at the end of inspiration where there is zero flow. independent of resistance
plateau is always less than PIP due to RAW

Question 19

raw

Answer 19

RAW is the resistance through the airway ( 6cmH2O)

usually takes 2 cmH20 of water from PIP