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How do ventilators work? - Alex Gendler

  • 0:07 - 0:11
    In the 16th century, Flemish physician
    Andreas Vesalius
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    described how a suffocating animal
    could be kept alive
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    by inserting a tube into its trachea
    and blowing air to inflate its lungs.
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    In 1555, this procedure didn’t warrant
    much acclaim.
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    But today, Vesalius’s treatise
    is recognized
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    as the first description of
    mechanical ventilation–
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    a crucial practice in modern medicine.
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    To appreciate the value of ventilation,
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    we need to understand how the
    respiratory system works.
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    We breathe by contracting our diaphragms,
    which expands our chest cavities.
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    This allows air to be drawn in, inflating
    the alveoli –
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    millions of small sacs inside our lungs.
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    Each of these tiny balloons is surrounded
    by a mesh of blood-filled capillaries.
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    This blood absorbs oxygen from the
    inflated alveoli
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    and leaves behind carbon dioxide.
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    When the diaphragm is relaxed,
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    the CO2 is exhaled alongside a mix
    of oxygen and other gases.
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    When our respiratory systems are working
    correctly,
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    this process happens automatically.
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    But the respiratory system can be
    interrupted by a variety of conditions.
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    Sleep apnea stops diaphragm muscles
    from contracting.
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    Asthma can lead to inflamed airways
    which obstruct oxygen.
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    And pneumonia, often triggered by
    bacterial or viral infections,
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    attacks the alveoli themselves.
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    Invading pathogens kill lung cells,
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    triggering an immune response that
    can cause lethal inflammation
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    and fluid buildup.
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    All these situations render the lungs
    unable to function normally.
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    But mechanical ventilators take over
    the process,
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    getting oxygen into the body when
    the respiratory system cannot.
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    These machines can bypass constricted
    airways,
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    and deliver highly oxygenated air to
    help damaged lungs diffuse more oxygen.
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    There are two main ways ventilators
    can work –
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    pumping air into the patient’s lungs
    through positive pressure ventilation,
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    or allowing air to be passively drawn
    in through negative pressure ventilation.
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    In the late 19th century,
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    ventilation techniques largely
    focused on negative pressure,
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    which closely approximates natural
    breathing
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    and provides an even distribution
    of air in the lungs.
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    To achieve this, doctors created a
    tight seal around the patient’s body,
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    either by enclosing them in a
    wooden box or a specially sealed room.
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    Air was then pumped out of the
    chamber, decreasing air pressure
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    and allowing the patient’s chest cavity
    to expand more easily.
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    In 1928, doctors developed a portable,
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    metal device with pumps powered
    by an electric motor.
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    This machine, known as the iron lung,
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    became a fixture in hospitals
    through the mid-20th century.
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    However, even the most compact
    negative pressure designs
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    heavily restricted a patient’s movement
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    and obstructed access for caregivers.
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    This led hospitals in the 1960’s to shift
    towards positive pressure ventilation.
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    For milder cases, this can be
    done non-invasively.
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    Often, a facemask is fitted over the
    mouth and nose,
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    and filled with pressurized air which
    moves into the patient’s airway.
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    But more severe circumstances
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    require a device that takes over
    the entire breathing process.
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    A tube is inserted into the patient’s
    trachea
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    to pump air directly into the lungs,
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    with a series of valves and branching
    pipes
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    forming a circuit for inhalation
    and exhalation.
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    In most modern ventilators,
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    an embedded computer system
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    allows for monitoring the patient’s
    breathing and adjusting the airflow.
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    These machines aren’t used as a standard
    treatment, but rather, as a last resort.
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    Enduring this influx of pressurized air
    requires heavy sedation,
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    and repeated ventilation can cause
    long-term lung damage.
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    But in extreme situations, ventilators can
    be the difference between life and death.
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    And events like the COVID-19 pandemic
    have shown
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    that they’re even more essential
    than we thought.
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    Because current models are bulky,
    expensive,
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    and require extensive training to operate,
    most hospitals only have a few in supply.
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    This may be enough under normal
    circumstances,
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    but during emergencies, this limited
    cache is stretched thin.
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    The world urgently needs more low-cost
    and portable ventilators,
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    as well as a faster means of producing and
    distributing this life-saving technology.
Title:
How do ventilators work? - Alex Gendler
Speaker:
Alex Gendler
Description:

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Video Language:
English
Team:
closed TED
Project:
TED-Ed
Duration:
05:21
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