respiratory analysis

1. DYNAMIC
MEASUREMENTS
Group 3

2. Objectives
At the end of the teaching session students will
be able to:
 State what is dynamic measurements.
 List some of the components of dynamic
measurements.

3. Dynamic measurements
Dynamic measurements, provide information about
airway resistance, and energy expended in
breathing or the work of breathing.

4. Dynamic measurements cont’d.
Dynamic measurements includes
 Rate or Frequency
 Minute volume
 Dead space

5. Dynamic measurements cont’d.
Respiratory rate or frequency
is the number of breaths per minute. Normal
respiratory rate ranges from 12-20 breaths per
min. At rest, generally the respiratory rate is
about 15 breaths/min.

6. Dynamic measurements cont’d.
Minute volume, sometimes called minute
ventilation, is the volume of air inhaled and
exhaled per minute. It is calculated by
multiplying tidal volume by respiratory rate.

7. Dynamic measurements cont’d
At rest, the minute volume is approximately
7,500 mL/min.
Eg. Vt × RR= MV
so 500ml × 15= 7.5 Liters per minute

8. Dynamic measurements cont’d
The dead space (measured in milliliters) is
the air contained in the airways or anatomical
dead space, plus the volume of alveolar air
that is not involved in gas exchange.

9. Dynamic measurements cont’d
Dead space occurs when there is a disease condition,
or disease conditions that renders lung tissue that
participates in gas exchange useless. For example,
air in an unperfused alveolus from pulmonary
embolism or, more commonly, air in underperfused
alveoli.

10. Dynamic measurements cont’d
Adult anatomical dead space is usually equal to the
body weight in pounds (e.g. 140 mL in a 140-
pound person). In a healthy person, dead space is
composed only of anatomical dead space.

11. Dynamic measurements cont’d
Dead space is calculated by subtracting the partial
pressure of arterial carbon dioxide (PaCO2) from
the partial pressure of alveolar carbon dioxide
(PACO2) (Morton, 2009).

12. Dynamic measurements cont’d
VD=PACO 2 - PaCO2

13. Dynamic measurements cont’d
The normal value of dead space in healthy
adults is typically less than 40% of the tidal
volume. The dead space/tidal volume ratio is
used to follow the effectiveness of mechanical
ventilation.

14. Dynamic measurements cont’d
To prove normal value:
if an individual weights 150 lbs then the anatomical
dead space is approximately 150 mL of air.
If Vt =500mls representing normal Vt
Then 150mls ÷ 500mls × 100 =30%

16. References
 Morton, F. (2009). Critical Care Nursing (9th
Edition ed.). (L. W. Wilkins, Ed.) Philadelphia,
USA: Wolters Kluwer.
 Morton, F.(2010). Critical Care Nursing (9th
Edition ed.). (L. W. Wilkins, Ed.) Philadelphia,
USA: Wolters Kluwer.

17.  International Anesthesia Research Society.
Respiratory function- dead space.
https://www.openanesthesia.org/aba_respiratory_fu
nction_-_dead_space/