Compliance and resistance_overview

2. In her teenage years is when she started
smoking. “It was the cool thing to do,” she
stated. Eventually she found herself smoking
up to two packs a day. According to her
biography, she started feeling the side effects
at the age of 25. When she reached the age
of 40 she was diagnosed with oral cancer and
started her radiation therapy. However, with
the radiation therapy she still finds herself
lighting up a cigarette. In the same year she
had another diagnosis which was throat
cancer and her doctor recommended to
remove her larynx. She was able to speak
with an artificial voice box. Unfortunately, she
passed away at the age of 53 in the year of
2013. Before she passed, she shared her
story to the public and helped move people to
stop smoking before it’s too late!

3. Michael is a veteran that is diagnosed with COPD
at the age of 44. He started smoking at the age of
9 when his sister handed him a cigarette stick.
“Smoking was something I did to fit in,” he stated.
Even though some of his family died because of
tobacco usage he still continues to smoke. He
attempted to quit smoking but he was never really
successful. At the age of 52 was the year he
finally stopped smoking because of his wake up
call. He awoke struggling to breathe and ended
up in the ambulance thinking if he’s going to live
or not. He lives, and had a surgery to remove the
diseased part of his lungs. Now, continues to fight
his battles on improving his health to be with his
daughter and spends time with his grandchildren.

4. DURING INSPIRATION:
 Elevation of the ribs by external intercostals and the contraction of the diaphragm will
increase our intra-thoracic volume.
 Our bronchial airways in a healthy lung will lengthen to increase diameter (passive
dilation).
 Increase in volume will decrease in intrapulmonary pressure.
 Decrease in intrapulmonary pressure creates a negative pressure gradient relative to
atmospheric pressure.
 Intra-pleural pressure will increase in negativity.
Air pressure changes during ventilation:
P(atm) > P (alveolar)  air moves into the lungs. = Inspiration

5. DURING EXHALATION:
 Lung will return to its normal state or passive constriction.
 Internal intercostals and abdominalis will start to compress which decreases the intra-
thoracic volume.
 Decrease in volume creates an
increase in intrapulmonary pressure.
 Increase in intrapulmonary pressure
creates a positive pressure gradient
relative to the atmospheric pressure.
 Intra-pleural pressure will be less
negative.
Air pressure changes during ventilation:
P(alveolar) > P(atm)  air moves out
of the lung. =Expiration

6.  In a quiet breath the diaphragm and external muscles
contract during inhalation while exhalation is a passive
process.
 As the lungs change in transmural pressures, they reflect a
force that is needed to battle airflow components.
› Raw and CL
 RAW: the air has contact with the airway walls where
there’s narrowing of airways due to a disease/infection
(e.g. asthma) leading to an excessive use of energy to
breath.
 CL :(100-200cmH20); where there’s distensibility of the
lung tissue. When the lungs have an increased
compliance in turn they will have a decrease in
elastance and visa-versa.
 Compliance=V/P & Elastance=P/V

7. Compliance: measures the ease of inflation or distendibility of which the lungs can
stretch.
 Increased Compliance = Easily inflated lungs
 Decreased Compliance = Lungs are becoming stiff
Elastance: measures lung stiiffness.
reciprocal of compliance.
 Increased elastance = Decreased compliance = Stiff Lungs
 Decreased elastance – Increased compliance = Easily inflatable lungs

8.  Measured during a period of gas flow or normal breathing. Therefore, it is influenced by
the patients’ lungs, chest wall compliance and patient-ventilator circuit.
 Normal lungs’ lung compliance and dynamic compliance ratio is 1:1.
 If patient have obstructed lungs, it would show a decrease in dynamic compliance due to
the alveoli distal to obstruction and causes insufficient “filling” time to its potential
capacity.
 Dynamic compliance can be calculated with the following equation:
VT Vt = Tidal Volume
PIP – PEEP PIP = Peak Inspiratory Pressure
PEEP = Positive Pressure
*** We subtract PEEP to get the actual change in pressure ***

9. I. Airway Resistance (RAW)
 measurement of frictional forces that must be overcome during breathing OR in simple
terms, anything that affects flow.
 Two types of flow: Laminar vs Turbulent Flow.
 Laminar Flow is when gas molecules
travels in an orderly manner. Produced
when inputting correct flow rates or by
removal of an obstruction.
Turbulent Flow is the complete opposite
of laminar flow. It is chaotic and it is usually
caused by an obstruction or excessive flow
rates.

10.  Poiseuille’s Law can be written as:
V= ∆Pr4π V = Flow
8ln ∆P = Change in pressure
l = tube length
n = Gas or fluid viscosity
r = tube radius
8/π = constant
This law is telling us that flow, is directly proportional to pressure and r4 (flow is a
function of a 4th power of the radius). However, flow is indirectly proportional to length
and viscosity of the tube.
 Why Poiseuille’s Law?
His law will help us recognize changes in the airway diameter and length affects the
pressure and flow.

11.  Airway Resistance (RAW) is defined as the pressure difference between mouth
and alveoli divided by the flow rate.
 Raw is calculated by the following:
Raw = ∆P (cmH20)
Flow (L/sec)
 Applying to mechanical ventilation
Raw = PIP – Pplat
Flow

12. Increased Resistance will be due to:
 Bronchospasm – abnormal contraction of smooth muscle in bronchi causing obstruction
or narrowing in the airway.
 Asthma or Chronic Bronchitis –
Inflammation of airways causing
obstruction and narrowing of the
diameter.
 Secretions – will cause obstruction
and the viscosity of it may lead
to immobility.
 Patient with increased work of
breathing and showing usage of accessory muscles and possible diaphoresis.
 By auscultation, patient’s breath sounds may sound wheezing, ronchi or stridor, if
ausculating on throat.

13. *** Before fixing the problem, make sure to asses your patients correctly.
 For bronchospasms, caused by asthma or chronic bronchitis
- Treat with bronchodilators, if severe treat with corticosteroids.
 For secretions
- Suction if needed, or some coughing techniques, mucolytics or proper
humidification.
 Stridor indicates edema or inflammation
- Cool mist

14.  Biting endotracheal tube
 Kinked ventilator circuit
 Inappropriate tube size (too small) for the patient’s airway
 Condensation in ventilator circuit.
SOLUTIONS :
 Insert a bite block in a patient’s mouth
 Make sure the circuits are hung nicely on the hanger and away from any thing that will
cause tangle or possible disconnection of the circuit.
 Switch to appropriate size for the patient.
 Make sure to drain any condensation that builds up in the circuit in the reservoir bag.

15.  Peak Inspiratory Pressure (PIP) is defined as pressure needed to overcome RAW and it
reflects on the conductive airways. Therefore, PIP is directly proportional to RAW.
 When assessing RAW during a ventilator check make sure to consider PIP.
 Also tidal volume (Vt), it is not quite as related to RAW as PIP, but decreased values of
Vt will show when RAW is present due to volume not fully delivered because of
obstructed areas.
 In the Pressure – Volume Loop on a
ventilator, the picture to the
right will show that RAW is present.

16. II. Static Compliance
 It reflects on the distendibility of small airway or the elasticity of lung tissues.
 We keep our lungs inflated even if we exhale with negative intrapleural pressure because
of the alveolar surface tension.
 Our type II alveolar cells will secret out
pulmonary surfactant that helps prevent
collapsed alveoli and helps stabilizes
alveoli.
 Inadequate production of pulmonary
surfactant will lead to stiff lungs which
would be difficult to perform breathing.

17.  When we measure static compliance (Cstat) it should be performed with no air flow, or by
pressing down the “inspiration hold” on a ventilator (the name varies on different
ventilators) to get the appropriate plateau time (0.5 – 1 sec).
 To identify an adequate plateau pressure on a ventilator graphic, it’s best to observe it on
a Pressure – Time Curve (picture on top).

18.  During a breath hold, Pplat or pressure in the alveoli will depress through the pores of
kohn, canals of lambert and channels of martin.
 Pplat or plateau pressure is needed to overcome elastic resistance (transalveolar
pressure).
 Static Compliance can be calculated as:
Vt Vt – Tidal volume
Pplat – PEEP Pplat – Plateau pressure
PEEP – Positive pressure
*** According to the formula static compliance is inversely proprotional to plateau pressure.
*** We subtract PEEP to get the actual change in pressure ***

19.  If Plateau pressure and static compliance are inversely proportional
then:
Decreased Static Compliance = Increased Plateau Pressure will be due to:
Pneumonia Pulmonary Edema
Pneumothorax Pleural Effusion
Loss of surfactant Neuromuscular disease
Atelactasis
The examples above will make it more difficult for lungs to inflate due to the
restrictive problem.
Increased Static Compliance = Decreased Plateau Pressure will be due to:
Emphysema – because there is greater dispersion of air in alveoli due to elasticity
loss.

20.  Airway Resistance (RAW):
6 cm H20 (intubated patients)
 Dynamic Compliance (Cdyn):
60 – 100 cm H20 (patient w/o ventilatory support)
30 – 40 cm H20 ( patient w/ ventilatory support)
 Static Compliance (Cstat):
70 – 100 cm H20 (patient w/o
ventilatory support)
< 40 cm H20 (patient w/
ventilatory support)

21. EMPHYSEMA
disappearing lung disease
smoking/genetically inherited
alveolar wall destruction
lung compliance
[ floppy lungs]
EM of healthy lung tissue
EM of emphysematous lungs
Terry and Michael’s Story
Why would having chronic obstruction and highly compliant lungs would
make it harder for them to breath out?
The lungs have been overstretched making it easy to inflate, leading
to low elastic recoil and working harder to force air out. Since they
have an increase in compliance, they also have an increase in static
lung volume (TLC,FRC and RV) as well as an increase in Raw.

22.  Decreased dynamic compliance with stable static compliance:
Your PIP will show an increase value on the vent, meaning there is an
increase in RAW which could indicate secretions or bronchospasms.
 Increased dynamic compliance with stable static compliance:
PIP will show a decreased value on the vent, which could mean that there is
an improvement of RAW indicating: removal of any obstruction.
 Decreased dynamic compliance with a decreased static compliance:
PIP and Pplat on the vent will both show an increase in value and could
indicate a combination of decreased compliance with an increase in RAW.
 Increased dynamic compliance with increased static compliance:
PIP and Pplat on the vent will both show a decreased value indicating improved
compliance and RAW.
 Remember that if there is a major change in dynamic compliance and a minor change in
static compliance assume that it is a RAW or conductive airway problem!

23. THE
END!!

24.  http://www.cdc.gov/tobacco/campaign/tips/stories/terrie-biography.html
 http://www.cdc.gov/tobacco/campaign/tips/stories/michael-biography.html
 http://apbrwww5.apsu.edu/thompsonj/Anatomy%20&%20Physiology/2020/2020%20Exam%20R
eviews/Exam%203/CH22%20Breathing.htm
 http://www.respiratorytherapyfiles.net/mechanical-ventilation.html
- physiology of ventilation
- airway resitance
 Des Jardins, Cardiopulmonary Anatomy and Physiology, 5th ed. Page, 92 – 98, 102. Print.
 Cairo, J.M. Pilbeam’s Mechanical Ventilation Physiological and Clinical Applications. 5th ed.
Page140. Print.
 Resistance and Compliance powerpoint By: Martin T. Kevin. BVE, RRT, RCP.
 Static Compliance powerpoint By: Bobbie Jimenez and Sue Trapp
 www.google.com for the pictures