mechanical ventilation is the process of using a machine to move air into the lungs
with positive pressure this is necessary when a patient is unable to adequately exchange oxygen
and carbon dioxide the principles of mechanical ventilation determine how the machine is able to
provide positive pressure and how it can be used to meet the specific needs of the patient and that
is the topic of this video so if you're ready let's get into it so what are the principles
of mechanical ventilation well respiratory therapists and those who work in critical care
must learn and understand the different principles and this includes ventilation
oxygenation lung compliance airway resistance dead space ventilation and respiratory failure each of
these principles is important in determining how much support is delivered to the patient
depending on their individual needs first let's talk about ventilation ventilation
is the physiological process of moving air in and out of the lungs during a breathing cycle it is
an essential component of respiration which helps ensure that oxygen-rich air enters the lungs while
carbon dioxide is being removed carbon dioxide is the primary variable of ventilation if too much
co2 builds up in the blood it raises the acidity and lowers the ph which can lead to ventilatory
failure oxygenation is the physiological process of absorbing oxygen into the bloodstream
during inhalation air enters the lungs and delivers oxygen molecules to the alveoli
where they diffuse across the alveolar capillary membrane and into the blood from there the oxygen
is carried by the hemoglobin in red blood cells to tissues and organs throughout the body ventilation
brings air into the lungs while oxygenation ensures that the cells within the body receive
adequate oxygen molecules now let's talk about lung compliance lung compliance is a measurement
of the lungs ability to expand and contract it is calculated by dividing the change in volume
by the change in pressure high lung compliance means that the lungs can expand more easily
while low lung compliance indicates lung stiffness there are two primary types of lung compliance
static and dynamic static compliance is the measure of the lungs ability to expand
when there is no airflow it is determined by the amount of pressure required to inflate the
lungs at a given volume dynamic compliance is a measure of the lungs ability to expand when
air flow is present it is determined by the amount of pressure required to produce a given flow rate
next up is airway resistance airway resistance is a measurement of impedance to the movement of air
through the respiratory tract during inspiration and expiration it is determined by the pressure
difference between the alveoli and the atmosphere factors that can affect airway resistance include
retained secretions bronchoconstriction foreign body aspiration and endotracheal tube condensation
in the ventilator circuit neoplasm of the bronchial muscle structure tumors compressing
the airway and an upper airway infection the airway resistance is inversely proportional to
the cross-sectional area of the airway this means that a smaller airway has greater resistance than
a larger airway dead space ventilation is defined as the volume of ventilated air that does not
participate in gas exchange therefore in this case plenty of air reaches the alveoli but there is a
lack of perfusion available for a gas exchange to occur which explains why dead space is known as
wasted ventilation there are three types of dead space anatomic alveolar and physiologic
anatomic dead space is the volume of air in the conducting airways that does not participate in
gas exchange it is estimated to be approximately one milliliter per pound of ideal body weight
alveolar dead space is the volume of air that reaches the alveoli but does not participate in
gas exchange due to a lack of perfusion this can occur due to decreased cardiac
output heart failure blood loss or a pulmonary embolism physiologic dead space is the total
volume of air that does not participate in gas exchange therefore it is the sum of the anatomic
and alveolar dead space switching gears just a bit now let's talk about respiratory failure
respiratory failure occurs when the lungs are unable to adequately oxygenate the blood or
remove carbon dioxide from the body there are two primary types ventilatory failure and oxygenation
failure ventilatory failure is the inability of the lungs to remove carbon dioxide from
the blood which results in respiratory acidosis ventilatory failure is caused by the following
hypoventilation a vq mismatch shunting or a diffusion defect each mechanism causes an increase
in the arterial partial pressure of carbon dioxide which ultimately leads to ventilation failure
oxygenation failure is the inability of the lungs to adequately oxygenate the blood
which results in arterial hypoxemia it is caused by hypoventilation a vq mismatch or
shunting however this type of oxygenation failure does not respond to supplemental oxygen therapy
which is known as refractory hypoxemia therefore it must be treated with mechanical ventilation and
increased levels of beep but again each of these principles are important when it comes to how
much support is being delivered during mechanical ventilation and they are ventilation oxygenation
lung compliance airway resistance dead space ventilation and respiratory failure respiratory
therapists must learn and develop an understanding of each type in order to initiate and manage
patients who are on the ventilator otherwise how will they know how much support the patient needs
and how would they know what adjustments need to be made to the ventilator settings
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think you will enjoy and just a quick reminder we are not doctors this video is for informational
purposes only thank you so much for watching have a blessed day and as always real easy my friend