Heart lung by pass unit

HEART-LUNG BYPASS UNITS; EXTRACORPOREAL

PERFUSION; OXYGENATORS, EXTRACORPOREAL MEMBRANE

Member:1. Ahmad Rafiqan Bin Nayan2. Muhammad Irfan Bin Alias3. Mohammad Al-Karim Tayasneh4. Mohd Izzad Samir Bin Iskandar

What is Heart-lung Bypass unit?

External systems that provide circulation, oxygenation, and filtration of theblood as a temporary substitute for circulatory and pulmonary function.

Type of Medical Purpose

Often used for open-heart surgery, such as coronary artery bypass grafting and cardiac valve replacement.

In some cases, used for extracorporeal membrane oxygenation (ECMO) in patients with respiratory distress syndrome or with respiratory insufficiency due to pneumonia, smoke inhalation, or other causes.

Technique of providing both cardiac and respiratory

 support  oxygen to patients whose heart and

lungs are so severely diseased or damaged that they can no longer serve

their function.

Block diagram of Heart-lung Bypass Unit

Process flow…

Principle of Operation

During bypass, the patient is heparinized to prevent blood from clotting within the heart-lung bypass circuit. (After bypass, anticoagulation must be reversed by protamine sulfate)

Heart is infused with a cardioplegic chemical solution (e.g potassium chloride) to stop its rhythmic contractions and reduce its metabolic requirements so as to avoid ischemic damage to the myocardium.

The blood flows to the oxygenator/heat exchanger for oxygenation, carbon dioxide removal, temperature regulation, and any necessary anesthetic exchanges.

Blood that pools in the surgical site is suctioned and collected in a cardiotomy reservoir, where it is filtered, defoamed, and either pumped or drained to the oxygenator.

The oxygenated blood is then returned to the patient, typically through the aorta, bypassing the heart and lungs.

Component

Extracorporeal perfusion pumps

Oxygenator

Perfusion monitoring and peripheral equipment

Closed-circuit systems

Extracorporeal perfusion pumps

Roller pump Centrifugal pump

Roller pumps: The pumps are designed so that one of

the rollers is always in contact with the pump-head tubing, compressing it and forcing the blood forward.

Pump-head occlusion is manually adjusted by the operator. Some pumps can provide pulsatile flow.

Advantages :1. Require low volume of blood for priming.2. The association with minimal

biocompatibility problems (because the tubing is the only surface that contacts the blood)

3. A low haemolysis rate (possibly due to the lack of blood backflow or turbulence).

Blood ruptur

e

Disadvantages: 1. Tubing will crack or release plastic

fragments that can become particulate emboli.

2. In the event of a tube blockage, there is a possibility that the pump will continue to operate and cause the tubing to rupture.

Centrifugal pump: Uses centrifugal force to move blood

through the system. Spinning cones or rotating fins create a vortex and force blood centrifugally through a port in the periphery of the pump head.

Flow output must be measured using a noninvasive sensor or a disposable probe inserted into the arterial line.

Advantage : Reducing the risk of generating

particulate matter in the blood. Provide protection against over

pressurization of the system in case of tubing occlusion.

Air-lock system- preventing air from being administered to the patient. If there is air, the filter will remove the air as the pump will continue function.

Disadvantage : Non-occlusive: not prevent blood backflow

from the patient if the pump stops, adding to the risk of air entry into the circulation.

Generally: Both a backup arterial pump and a

connection to an emergency power system are necessary to ensure reliable pump operation.

A hand crank for manual pumping is recommended as an additional backup as it can provide the high rotational speeds required by centrifugal pumps.

Oxygenation

Example :Membrane oxygenator. These devices usually have an integral heat exchanger to control the temperature of the blood.

Oxygenator must be primed before use with lactated Ringer’s solution of 5% dextrose, to remove air pockets and bubbles from the bypass circuit.

Consist of a gas-permeable membrane separating a thin layer of blood from the oxygenating gas.

Three major types of membrane oxygenators are PLATE, COIL, and HOLLOW FIBER.

As a safety precaution, arterial blood is usually pumped through an in-line arterial filter, which helps trap particulate matter and gaseous emboli before they reach the patient. If the filter becomes clogged, the blood can be diverted through an arterial-line shunt that has its own filter.

After oxygenation and filtration, the blood is pumped into the body through a cannula placed in the ascending aort or femoral artery at a rate of four to six liters per minute (L/min), depending on the patient’s physiologic requirements.

Perfusion monitoring and peripheral equipment

To maintain the desired temperature in the heat exchanger water mixer regulates delivery of warming and

cooling water mixer is typically part of the pump console

and includes a thermometer and a backup pressure-relief valve

A separate electric water heater/cooler can be used instead of a mixer

Thermistor probes are placed at various points on the patient and in the extracorporeal circuit

Blood gases can be monitored from drawn samples, by an in-line differential oxygen monitor

Pressure monitors record left atrial, pulmonary artery, and systemic arterial pressures

Electronic safety devices have been incorporated into heart-lung bypass units, with varying degrees of acceptance

Most manufacturers offer ultrasonic bubble detectors, which use an ultrasonic transducer and detector to shut down the pumps automatically when gaseous emboli are detected in the arterial line.

Level detectors-which alarm when blood falls below acceptable levels in the oxygenator, cardiotomy reservoir, or other components.

Some centrifugal pumps include a backflow alarm to alert the clinician to retrograde blood flow within the system.

Closed-circuit systems

Minimally invasive closed-circuit systems (also called mini-bypass systems) are designed to be used intermittently during beating-heart surgery.

Incorporates the pump, filter, and oxygenator in one housing and is stationed on the main console.

It small, use shorter tubing and can be placed closer to the patient as result patient’s blood spends less time outside the body

 less priming is required- this decreased extracorporeal blood, coupled with less diluted blood, results in less blood damage.

REPORTED PROBLEM

EMBOLISM IMPROPER OR DEFECTIVE CONNECTION

IN TUBING FAILURE OF SYSTEM HARDWARE PROBLEM WITH CERTAIN ANCILLARY

PORTION OF EXTRACORPORCEAL CIRCUITS

INTERFERENCE BETWEEN HEART LUNG MACHINE AND BISPECTRAL INDEX(BIS) MONITOR

PURCHASE CONSIDERATION

ARTERIAL PUMP- ROLLER OR CENTRIFUNGAL CONFIGURATION

1 0R 2 SUCTION PUMP CARDIOPLEGIA PUMP BACKUP ARTERIAL PUMP-EMERGENCY

POWER SUPPLY MANUAL CRANK DISPOSABLE OXYGENATOR

OTHER CONSIDERATION

DEGREE OF MODULARITY OF EACH SYSTEM

PROCEDURE ROOM ELECTRICALY CIRCUITRY AND CAPACITY BE ASSESSED

ENVIRONMENT CONSIDERATION

GREEN SHIPPING AND PRODUCTION METHOD

ENERGY EFFICIENCY BIS(2-ethyhexly)phthalate (DEHP)- FREE

DISPOSABLE

STAGE OF DEVELOPMENT

DISPOSABLE COMPONENT

HEPARIN-COATED

EXTRACORPOREAL

COMPUTERIZED PERFUSION CONTROLLER

RATCHED STYLE HANDPIECE AND

ADJUSTABLE

CARDIOPULMONARY BYPASSS SYSTEM

Biomedical Benchmark

IPM Frequency

4 times per year