Download Compliance and Resistance Overview

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!
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.
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
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

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
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

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
PIP – PEEP
Vt = Tidal Volume
PIP = Peak Inspiratory Pressure
PEEP = Positive Pressure
*** We subtract PEEP to get the actual change in pressure ***
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.

Poiseuille’s Law can be written as:
V=
∆Pr4π
8ln
V = Flow
∆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.


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
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.
*** 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

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.

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.
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.

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).

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
Pplat – PEEP
Vt – Tidal volume
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 ***

If Plateau pressure and static compliance are inversely
proportional then:
Decreased Static Compliance = Increased Plateau Pressure will be due to:
Pneumonia
Pneumothorax
Loss of surfactant
Atelactasis
Pulmonary Edema
Pleural Effusion
Neuromuscular disease
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.

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)
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.
EMPHYSEMA
disappearing lung disease
smoking/genetically inherited
alveolar wall destruction
EM of healthy lung tissue
lung compliance
[ floppy lungs]
EM of emphysematous lungs

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!
THE END!!

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%20Exa
m%20Reviews/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