OverviewHeart-Lung Machine – blood

pumping machine that takes over the functions of the heart and lungs during surgery (i.e. open-heart surgery)

Most commonly used to perform a cardiopulmonary bypass (CPB)

CPB allows for the heart to stop beating, which makes it easier to operate on, and surgeons can operate in a blood-free area

Current Methods Composed of: a chamber that receives all the

blood from the body (right atrium of the heart), pumps that move the blood through an oxygenator (right ventricle),oxygenator removes the carbon dioxide and adds oxygen to the blood (lungs)

Machine continues by pumping the oxygenated blood back to the body (left atrium and ventricle) using a series of tubes

The heart-lung machine itself is operated by perfusionists during surgery, and at the end of an operation, the surgeon gradually lets the patient’s heart resume its normal functions

Results: the ability of a surgeon to perform an open-heart surgery in a blood-free zone while the heart is not beating

CPB allows for supporting the circulation of the blood; induce total body hypothermia, where the body can be maintained for up to 45 minutes without perfusion (blood flow)

Heart-Lung MachineThe heart-lung machine:

Consists of a chamber that receives the blood from the body

Blood is pumped by machine through an oxygenator

Oxygenator removes CO2 and adds oxygenPump then pumps this newly oxygenated blood

back to the bodyConnected to patient by a series of tubes that

the surgical team places

Heart Lung Machine

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Limitations and Future If blood flow were to be stopped at normal body temperature, permanent

brain damage will occur in just a few minutes, followed by almost certain death shortly after.

“Pumphead” syndrome – some effects can include defects to attention, concentration, short term memory, and fine motor function

Allows for medications and anesthetics to be administered directly into the blood, adding them to the blood in the heart-lung reservoir, arriving immediately to the patient

The clear advantage - allow doctors to operate in a blood-free area, should contribute to less surgical error

In the future, the heart-lung pump will hopefully become portable, allowing for paramedics to aid heart attack patients on the scene The device will be further developed to allow for less brain damage after the surgery.

Oxygenators

Membranous

Bubble

Membranous OxygenatorsImitate the natural lung by interspersing a thin membrane of either micro porous polypropylene or silicone rubber between the gas and blood phases.

With micro porous membranes, plasma-filled pores prevent gas entering blood but facilitate transfer of both oxygen and CO2.

The most popular design uses sheaves of hollow fibers connected to inlet and outlet manifolds within a hard-shell jacket.

Bubble OxygenatorsVenous blood drains directly into a chamber into

which oxygen is infused through a diffusion plate (sparger).

The sparger produces thousands of small (approximately 36 µm) oxygen bubbles within blood.

Gas exchange occurs across a thin film at the blood-gas interface around each bubble

Produce more particulate and gaseous microemboli are more reactive to blood elements.

Heat ExchangersControl body temperature by heating or

cooling blood passing through the perfusion circuit

Temperature differences within the body and perfusion circuit are limited to 5°C to 10°C to prevent bubble emboli