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This is a medical emergency.
A 42-year-old manwith a massive gastrointestinal hemorrhage.
His blood pressure has already droppeddangerously low and every second counts.
Each year, millions of peopleenter our hospitals
for some form of treatment.
We have come to dependon the healthcare team that treats us,
and we rely on the drugsand medical devices they use.
A defective medical devicewhich finds its way into the hospital
can have some important consequences.
If the device fails,it may seriously impair
the treatment of the patient.
As a result, the morale and confidenceof the healthcare specialist
and their patientscan be severely damaged,
and hospitals and doctors can becomethe targets of massive malpractice suits.
The confidence patients havein their doctors and hospitals
must be actively protected byhealthcare practices that are as reliable
and as safe as we can make them.
This means educatingand licensing the hospital staff
as well as maintaining high standardsin the production of the things they use.
Many of the devices used in today's hospitalsare made of plastic.
Often, they are disposable.
These devices,like any other manufactured objects,
are subject to defects.
Some defects affectthe function of the device
while others are merely cosmetic in nature.
In either case,every attempt is made to eliminate
the defective device as well asthe manufacturing conditions
which gave rise to them.
Defects in plastic medical devicescan occur at various stages of manufacture.
For this reason,strict quality assurance procedures
must be followedduring the entire process.
These procedures begin at the timeraw materials or components
enter the plant at the receiving dock.
A unique code number is assignedto the incoming material,
providing a means of tracing itthroughout all phases of manufacture.
Another important way to ensure qualityis to keep untested materials
physically isolated from the stock supplyused to fill work orders.
This isolation is maintaineduntil initial physical tests show
that the raw materials or componentsmeet the required specifications.
In this case, rubber plunger tips suppliedas a component from another company
are being sampled.
First, they are giventhe required physical tests,
which in this case measures theconcentricity or circularity of the part.
If they successfully pass this test,the device history record
is signed accordingly.
If they don't pass the test,they may be either rejected
and returned to the vendor,or the specifications will be reviewed
by some established review panel to decidewhether or not the variation will make
a difference in the product's usability.
If they decide the variationwill not affect the product,
a written exception will be includedin the device history record.
If the initial physical test fordimensional, visual, and mechanical
properties indicate acceptability,the materials
are then tested biologically to determineif any soluble toxic substances
or fever-producing agentsknown as pyrogens are present.
The materials are measured and autoclavedwith a sterile saline solution.
Then the extracted liquid is injectedinto test mice.
The mice are weighedand logged before injection.
They are then watched carefullyand their reactions logged.
The record isnotated with these observations.
Having passedthe crucial physical and biological tests,
the components are labeled accordinglyand are transferred
from the quarantined areainto the warehouse until they are used.
The basic quality assurance proceduresfor handling plastic pellets or resins
are pretty muchthe same as those four components.
However, in the case of these raw materials,chemical tests may be carried out
to determine the presenceof chemical adulteration
and to verify adherenceto chemical specifications.
This infrared spectrophotometer is usedto produce spectrographs of new materials
for comparison with the spectrographsof control materials.
Ultraviolet tests are also conductedin this laboratory.
All these tests are conducted to checkthe medical usability of the materials
before they are acceptedby the manufacturer of the devices.
If acceptable,they are signed off by the lab technician.
Production of a plastic devicefrom the pellets
involves melting the plasticand forming it into the desired shape.
The plastics usedare generally of two types.
Thermoplastics are wax-like substanceswhich soften when heated and harden
when they are cooled.
The others are the thermosetswhich undergo chemical reactions
when heated causing themto set up into a solid.
The properties of plasticsare often tailored
to meet particular needsthrough the addition of additives.
Antioxidants retard oxidationand eventual degradation of the product.
Anti-static agents minimizethe buildup of electrical charges
during the production stages.
Flame retardants minimize fire hazards.
Lubricants improvethe processability and appearance
of the plastic products.
Plasticizers improvesoftness and processability.
Stabilizers preventthe degradation of materials.
Fillers may reduce costs, provide body,speed the cure or hardening,
minimize shrinkage,improve thermal endurance,
or provide special electrical,mechanical, and chemical properties.
Catalysts induce chemical reaction.
Colorants colorthe plastic such as dyes,
which usually supply brilliant,transparent color, organic pigments,
which are discrete solidparticles of dyes and inorganic pigments
made of salts and oxides of metals.
When pigments are added,tumblers like these
are used for mixing the dry colorswith the pellets.
There are a variety of means by whichplastics or their compounded mixtures
can be formed into useful objects.
The two typesof injection molding machines
and the extrusion machines commonly usedall start out in the same way.
Pellets are placed in the hopper,in this case by the vacuum tubes
we see hanging from the hoppersinto the barrels of pellets
From the hopper,they drop by gravity into the feed system.
The feed mechanism in turndrops the pellets
through the feed throatleading into the heating cylinder.
In the plunger injection molding machine,a ram moves the pellets
through the heating cylinderwhile the screw injection molding machine
transfers the pellets with a screw.
The additional heatgenerated by the shearing of the pellets
in the screw machine,results in a quicker melt.
Not only can the screw machinemold products faster,
but a more homogeneous mix is obtained.
The heat in this cylinderconverts the plastic from solid pellets
to melt form.
The electric heating bandsusually hidden under the cover
provide the heat that melts the pellets.
The molten plastic is called a melt,which looks like
a long squirt of toothpaste.
By the time the plastic has reachedthe forward end of the cylinder,
it is ready to beinjected through this nozzle into the mold.
Moving the softened materialrequires tremendous injection pressure.
Injection plungers may exert pressureof more than 20,000 pounds per square inch
on the melt to force it through the nozzleinto a channel called a sprue bushing.
The mold is then clampedshut with either a toggle or a ram clamp.
After the mold is closed,hot plastic is injected
through the sprue bushing.
From the sprue bushing,it flows through the sprue into the cavity
via the runner system.
When the parts have set rigidly enoughto withstand ejection without distortion,
the mold is openedand the molded parts still attached
to the sprue or to the runnersare pushed out of the mold
by ejector pins.
The entire process is a complicated one,and each step has
to work properly for the productionof high-quality molded products.
When things don't work properly,a number of defects can occur.
Short shots are causedwhen not enough melt enters the cavities
resulting in an incomplete molded part,such as we see
in this plastic razor handle.
Flashing, which is seenas extra material adhering to the part
can come about from moldswhich are worn or improperly designed,
or which are runat the wrong temperature or pressure.
Embedded debris is generally the resultof dirt or some other foreign material
getting mixed in with the plasticbefore molding.
Surface blemishes may appearas silvery streaks or burn marks.
These defects usually resultfrom improper melt temperature,
too much release agent,improper compounding of additives,
or the mold being too hotand actually burning
the surface of the molded part.
Sink marks are surface imperfectionslike a dimple or corrugation
caused by excess heat or unevenlymixed stabilizers,
which usually do not causefunctional problems.
The example is seenin the neck of this funnel-shaped part.
A warped part usually resultswhen a part is released
from the molding cyclebefore it has cooled sufficiently
to hold its shape.
Cracking is a defect that can resultfrom a part sticking to the mold
when the ejection pins in the moldare trying to push it out.
Cracking can also occurif the plastic molding resins
have not been compoundedor stored properly.
Moisture can also be a problem,especially in certain plastics
like polycarbonates,which must be dried
before introduction to the hopper.
Weak weld lines aredifficult to detect with the unaided eye.
They occur when the pathof the plastic flow through a mold
is divided and then rejoins itself atanother part of the mold forming a weld.
A defect can occurif the plastic has cooled
before it joins back together,or bubbles are captured
in the melt where it joins.
Detection of this type of defect is donewith a special polarized light source.
Remember, improper control of heat,
pressure, molds, and resins
can lead to problemsin injection molding.
Extrusion isanother plastic-forming process
in which careful control of the variablesis necessary.
The melt is forcedthrough an orifice called a dye
into the shape of the desired product,which is usually tubing.
In tubing, the dyewill be a ring-shaped opening
for the melted polymer to exit,and the mandrel, which is the post
making up the solid center of the dyewill be drilled out
so that forced air can enter the tubingas it is extruded.
In some cases, there is a mandrel wire,which takes the place
of the solid mandrel in the dye.
The polymer is extruded on this wirewhich is later removed
leaving a hollow tube.
The extrudate is still moltenas it enters the dye.
It must be cooled and conveyedso that its shape is not distorted.
For tubing such as catheters or airways,this is done
by pumping air through the tubing,keeping it at a constant pressure
as it moves throughthe water-filled cooling trough
to the far endwhere it is pulled through these rollers.
This hard-walled tubing is being cutto predetermined lengths.
It is checked for concentricity,
diameter, length, and consistency.
At this air-driven take-up rollused for pliable tubing, there is
a constant watch of the take-up speed.
If the extrudate is pulledfaster or slower than indicated
in the manufacturing procedures,the product may not meet specifications.
Common defects in extruded tubinginclude surface blemishes or dye streaks,
which are causedby incomplete melt or oil and grease
on the dye and are consideredmostly cosmetic in nature.
Another common defect is a variation inthe inner and outer
diameters of the tubing.
This defect is caused byimproper adjustment of the polar rollers
or the rate of melt extrusion.
Both extrusion and injection moldingare subject to certain common problems.
These problems occur from contaminationof the plastic used to produce the melt.
Contamination may occurwhen the runners and scrap
from a plastic fabricating operationare ground for reuse.
An operator may inadvertently mixtwo types of plastic scrap together.
Such a mix mayonly cause cosmetic problems
in the products produced from such a mix,but in some cases,
physical properties of the mixmay be altered to such an extent
that the function of the form devicewould be impaired.
Contamination by the grinding machinescan also occur.
This is best avoidedby using grinding machines,
which are color-codedfor use with specific plastic types.
There are also sources of contaminationnear the plastic forming machines themselves.
Paint scale, oil, dust,insects, and other vermin
can fall into the hopper or drumof pellets which are fed into the machine.
This form of contaminationcan be controlled by using covered drums
and hoppers and vacuum hosesfor the transfer of pellets
to the machines.
Common sense and good housekeepinghelps too.
We have followed the flowof materials from receiving
through the various fabricating processes.
We have seen how defects can arisein a host of different ways.
Now, one last processing step remainsbefore the plastic medical devices are
ready for shipment from the plant,they must be sterilized.
Like every other stepin making a high-quality product,
the sterilization must be carried outunder exacting conditions.
There are two major methodsof sterilization of plastic devices,
radiation, and ethylene oxide.
This sequence shows some phasesof a typical ethylene oxide sterilization.
After the itemshave been packaged and labeled,
small boxes containingthe biological indicators are attached.
The biological indicators containliving microorganisms whose failure
to grow in a suitable culture mediumafter sterilization indicates
that sterilization has been complete.
The pellets are then movedto a pre-conditioning room
where humidity and temperatureare rigidly controlled
for a specified periodin order to humidify
the devices and packing material.
This practice has been found to makethe subsequent sterilization more effective.
From this pre-conditioning room,the pellets will go
into large sterilization chambers.
These pellets are rolled into the chamber,making sure that the indicators
are systematically placedthroughout the chamber to
ensure thorough effectivenessof the sterilization cycle.
It is importantthat the manufacturer has qualified
a cycle for thingslike the specific load configuration,
product, and material.
This automated system monitorsand documents the temperature,
humidity, pressure, time,and the concentration
of ethylene oxide gasused during the cycle.
The circular graph is also usedas backup documentation
of the sterilization cycle.
Once the gas has been drawn offand scrubbed,
usually through water filters,the chamber is opened
and the pellets are aeratedand removed to a quarantined area.
The biological indicators are removedfrom the pellets
and taken to the sterilization laboratorywhere the indicators are tested.
This facility is a clean room,which prevents contamination.
The spore strips are removed hereand added to a culture broth.
This broth is then incubated.
After about 10 days,the broth culture is examined.
If the sterilization has been effectiveunder the programmed conditions,
the devices may then bespot checked for proper performance
before being released for distribution.
[siren wailing][music]
We're going to need an IV [?]
Now, have you hadany swelling at all up in here.
No.
Quality medical products areessential for quality medical care.
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