HLM « Magazine

HLM

What is HLM? It is Heart Lung Machine.

Can you imagine how difficult it is to perform surgery on the heart while it is pumping blood into the vessel or artery? Because of this difficulty, it would be better if the doctors can stop the heart function temporarily and bypass it from the body. This procedure is called Cardiopulmonary bypass (CPB), a term is known as hypothermia; it essentially stops the heart function and stops the blood flow to the body. This can’t be done without the support of HLM.

The procedure to stop heart function from the body is done by pumping crystalloid solution. HLM will take over the pump function of the heart and then it supplies blood and oxygenation to other parts of the body to keep the patient alive. It is very important to maintain a proper ratio of crystalloid and blood mix throughout the operation. This is written in a very simple way to understand the basic idea of bypass surgery. The actual procedure is much more complex. The complexity of the procedure is simplified by software with command, alarm and continuous data display to the console for doctors, perfusionists, and nurses.

Because of its complexity, engineers, and designers that consists of electrical, mechanical, software and manufacturing to use the state of the art design from its concept to the end the product.

The software is making it very simple from the user interface (UI) for doctors, nurses, and perfusionists. This simplicity makes the operation very successful. Importance of the user interface has greatly improved the success of this procedure. Underneath the visible aspect of the UI software layer, there are many other software layers work to communicate with patients’ psychological data and associated hardware for data accusation and then process the data to the final communication layer of software hands-on information to UI. Extreme care is taken to process all the data with an algorithm. These algorithms are developed by doctors, scientists, clinical people and software developer. What good is the data to users if the final data is not very useful to the physicians and surgeons?

Production, manufacturing technique requires dust free environmental controlled facility. These processes require zero tolerance of failure of hardware and components.

Stringent guideline developed by quality control group is used for the entire process.

Final system design demands extreme test requirement so that it enables no fault from the system, software, and UI. The process ensures that the machine will perform better and reliably than the requirement guideline by FDA. Final certification from FDA is required from the standpoint of quality and reliability.

See below for few simple pictures, they will enable us to understand how it works. Basic important parts are pumps, valves, sensors, display control panels.

Arterial pump in the system circulates blood throughout the body and oxygenator is used to allow red blood cells for receiving oxygen as well as reduction of carbon dioxide level. This system is mimicking the function of a heart and the lungs. Thus, HLM maintains blood flow to entire body organs and tissues when doctors will go through the surgical procedure for the defective heart. As indicated before, heart at this time is in artificial hypothermia state.

Besides pumps, many valves, clamps, and tubing are used to control the flow of blood, solution throughout the system and the body. The highly sophisticated control logic is used to control the hardware, flow to maintain proper pressure, volume, and temperature of the blood and solution.

The surgeon places a cannula in the right atrium to withdraw blood from the body. The cannula is connected to tubing filled with isotonic crystalloid solution.

Venous blood that is removed from the body by the cannula is filtered, cooled or warmed, oxygenated, and then returned to the body.

The cannula is used to return oxygenated in the ascending aorta, or the femoral artery. During the procedure, hypothermia may be maintained.

Maquet is one of the leading developer and manufacturer of HLM. A team of highly talented engineers and software developer coupled with strong quality control and manufacturing group created the state of the art HLM. I am proud of being a member of Maquet team. See few pictures of the team on next page.

Maquet was founded in Germany in 1838; it was a pioneer with innovative hospital products. A Maquet table was used for the first heart transplant surgery in 1967, in South Africa. Maquet is a division of Getinge.

Getinge is a global provider of innovative solutions for operating rooms, intensive-care units, sterilization departments and for life science companies and institutions.

For more info: – click

https://www.maquet.com/int/

https://www.getinge.com/us/

Other competitors: –

Other popular manufacturers are Medtronic, Sorin, and Terumo.

Sorin Group is a global, medical device company and a leader in the treatment of cardiovascular diseases.

Medtronic offers the Century™ Heart Lung Machine (HLM) to customers globally.

Typical block diagram of HLM from Royal Children’s Hospital, Melbourne – (Google)