We offer now proven and effective engineering controls that significantly reduce the risk of infection by bloodborne pathogens to healthcare workers who perform a test about 300 million times a year in this country. This important screening test is known as the Packed Cell Volume (PCV) as determined by the microhematocrit method.

The NCCLS (National Committee for Clinical Laboratory Standards) sets standards in the area of medical laboratory testing and is composed of knowledgeable professionals from academia, government and industry. The NCCLS in May, 1985, (H-7A), published the Approved Standard titled the "Procedure for Determining Packed Cell Volume (PCV) by the Microhematocrit Method". This method introduces a significant risk of accidental inoculation of bloodborne diseases to the laboratory worker or other personnel performing the test. This standard procedure is used by numerous healthcare delivery organizations such as: hospitals, blood banks, hospital and commercial plasmapheresis centers, government and private research centers, commercial laboratories and physician's offices.

Annually in the U.S., using the NCCLS Standard Procedure by the microhematocrit method, an estimated 250,000 skilled and unskilled healthcare workers perform this test routinely.

For those of you who are not familiar with this test, we will explain it as follows:

The hematocrit, or more exactly, the microhematocrit is the packed cell volume of red blood cells expressed as a percentage of the volume of whole blood in a sample. The determination of the hematocrit is generally performed using a small capillary tube containing 50 to 70 microliters of blood sample. The microhematocrit method is currently the most convenient, simple, accurate and inexpensive way to screen patients and blood donors for the degree of anemia, polycythemia, hydration status, etc.

The tools required for performing the test with a skin puncture specimen are a fingertip puncture means such as a lancet, a disinfectant cleansing swab, gauze pad, and NCCLS prescribed thin glass capillary tubes 75mm long, a tray of clay-like sealing material, a microhematocrit centrifuge and a reading device to determine the percentage of packed red cells. OSHA now prescribes the use of latex gloves.

The NCCLS Approved Standard for performing PCVs by the microhematocrit method is summarized as follows: (l) fill the capillary tube directly from a freely flowing skin puncture. (2) Wipe the outside of the tube with gauze. (3) Close off the tube bore (collection end) with the tip of the finger. (4) Seal the the capillary tube by placing the dry end into the tray containing sealing compound and remove from the tray. The sealed tube is then placed into the microhematocrit centrifuge capable of sustaining relative centrifugal force of 10,000 to 15,000 x G and spun for 5 minutes. Following centrifugation the packed red cells are measured on a card scale and the results are expressed as a percentage of the total blood sample collected.

There are several serious risks of bloodborne infection to the healthcare worker when using the NCCLS Approved Standard. First, the use of fragile capillary tubes frequently cause accidental self-inflicted fingersticks while manually pressure sealing the tubes with clay-like sealants. A preliminary survey of laboratorians and other healthcare workers, show this accident occurs with sufficient frequency to establish that manual pressure sealing of capillary tubes is extremely hazardous.

Fill the Capillary Tube.
Latex gloves should be sufficient protection.
 

Close off the tube bore with the tip of the finger.
This is required immediately after collecting the blood to prevent gravitational drainage of the sample from the tube. The presence of fractured or splintered glass on the end of the tube can cause accidental skin puncture. Latex gloves may not provide sufficient protection against sharp edges. Direct skin contact with blood is readily possible. Self-sealing capillary tubes eliminate these exposures.

Seal the capillary tube.
The procedure is to place the dry end (opposite the sampling end) into the tray with sealing compound. Volume displacement of the sample, if overfilled, can cause spillage with subsequent contamination of the operator's finger. The blood sample simply overflows out the end opposite the end being sealed. When sealing the tube, applying excessive finger pressure can easily break the tube at the end or in the middle. This can happen more frequently when technicians disregard sealing the tube at a 90 degree angle in favor of a more convenient and widely used bench-top vertical position. Breakage also occurs when applying normal pressure into sealants containing voids or impactions of broken glass particles. In every case, accidental self-inflicted wounds with potentially infectious blood are possible. Self-sealing capillary tubes eliminate all these high risk exposures.

Centrifuge the blood-filled capillary tube.
Insufficient or improper collection of sealing material leading to "Blow-out" (total loss) or leakage (partial loss) of sample. Centrifugal force expels a portion of, or all of the sample as potentially hazardous aerosols. The self-sealing capillary tube significantly reduces "blow-outs" and "leakers".
 

Reforming clay sealants.
Laboratories use clay-like slabs to seal microhematocrit tubes. These slabs are often contaminated with previous blood samples and possibly small fragments of broken glass. In an effort to economize, some technicians reform the slab using their finger. Direct blood contact with the skin and/or inoculation by splintered glass is a risk under these conditions. Clay sealants and associated hazards are eliminated when using self-sealing capillary tubes.

Sealing the wrong end of the capillary tube.
The standard method requires sealing the dry end of the tube.

This step in the procedure requires direct finger contact with the blood collection end of the tube. Many technicians fear this step and attempt to seal the tube on the collection end. In this case, the blood sandwiches between the sealant and the inner wall of the tube and the sample easily passes around the sealant plug under centrifugal force. The blood also acts as a lubricant enhancing the chances that the clay sealant will migrate out the end of the tube while being centrifuged.

The urgent and unfulfilled need for capillary tubes that will provide greater safety to the healthcare workers who are required to perform PCVs by the microhematocrit method, was realized when it became well known that a physician accidentally inoculated himself with the human immunodeficiency virus (HIV) while manually sealing a microhematocrit capillary tube. Although we are not aware of other similar cases, it is our belief that this incident is not unique. However, several cases of accidental inoculation of hepatitis B virus (HBV) have been brought to our attention. OSHA's most recent proposed rules for Occupational Exposure to Bloodborne Pathogens states "The available evidence indicates that an exposure, resulting from an injury with a needle or other sharp object, carries the highest risk of HIV or HBV infection." We believe that the NCCLS Approved Standard for the "Procedure for Determining Packed Cell Volume by the Microhematocrit Method" has, is, and will continue to be, a major cause for accidental transmission of Hepatitis and most probably HIV.

Considering the increasing spread of bloodborne infections, the number of PCV microhematocrits performed, and the frequency rate of blood samples lost due to accidental breakage, "blow-outs" and "leakers", we believe the process of manually sealing conventional capillary tubes presents an extremely high risk opportunity for accidental transmission of bloodborne diseases to healthcare workers. The risk of accidental inoculation, while manually sealing capillary tubes, can be totally eliminated with the unique and now available engineering controls - the self-sealing capillary tube. Additionally, other risks associated with this procedure, are dramatically reduced.

A recent survey of 50 healthcare institutions (hospitals, blood banks, plasmapheresis centers and doctor's offices) was conducted to quantify both the incidence of accidental breakage while manually sealing capillary tubes, and the lost samples due to "blow-outs" and "leakers". The average incidence of breakage while sealing was 4% with "blow-outs" representing 10% of the total of 14% of all samples lost. The ranges were from 2 to 7% for accidental breakage and 5 to 20% for "blow-outs". These observations lead us to the following alarming conclusions. Based on the total annual consumption rate of conventional microhematocrit capillary tubes, the high risk opportunity for accidental fingersticks while manually sealing blood filled capillary tubes, is calculated to be at twelve million (12,000,000) times per year involving over two hundred thousand (200,000) healthcare workers. Another thirty million (30,000,000) blood samples are lost due to "blow-outs" while centrifuging. "Blow-outs" result in repeat collections, hazardous aerosols, blood contaminated centrifuges and hazardous clean-up.

Our ongoing survey, now totaling over 300 healthcare workers who on a regular basis perform PCV microhematocrits, reveals that 98% admit to having at least one (1) accidental fingerstick while manually sealing blood filled capillary tubes.

The important risks eliminated by self-sealing capillary tubes are: (1) accidental skin punctures associated with closing off the bore of blood-filled capillary tubes with the finger, (2) accidental skin punctures from "snapping tubes" while manually sealing and, (3) the deplored practice of "re-smoothing" (with the index finger or thumb) blood-contaminated clay sealing materials often imbedded with glass slivers which can easily penetrate latex gloves.

Other risks significantly reduced are the incidence of capillary tube "blow outs" (total loss of samples ), "leakers" (partial loss of samples) leading to hazardous aerosols, hazardous clean-up of blood-splattered centrifuges, handling and disposal of waste items such as: blood-contaminated clay sealants, capillary tubes and cleaning materials.

The self-sealing capillary tube has been found to be highly reliable as evidenced by a study conducted at a high volume hospital user in the Baltimore area. Prior to the self-sealing tube, the hospitals Hematology Department was experiencing greater than a 3% breakage rate while manually sealing the tubes and greater than a 20% loss rate of samples from "blow-outs" and "leakers". The testing was conducted by laboratory professionals who routinely use the microhematocrit method for PCV determinations. Since March of 1989, the same professionals have performed to date, over 61,000 microhematocrit determinations using self-sealing capillary tubes. First, the results show a 100% reduction (= total elimination) of the high-risk procedure of manually sealing capillary tubes. Second, the incidence of samples lost due to "blow-outs" and/or "leakers" has been less than an impressive 1%, as compared to greater than 23% losses obtained performing by the Approved Standard method. It is clear that manual sealing of capillary tubes is woefully inferior to self-sealing, using self-sealing capillary tubes. Third, a 96% improvement in reducing other risk factors associated with occupational transmission of bloodborne pathogens was found. These risk factors include hazardous aerosolizations of blood created by "blow-outs" and "leakers" and exposure to blood while cleaning blood-splattered centrifuges.

Another independent study conducted in January, 1989, by a major plasmapheresis center experienced only two (2) sample losses out of 1,200 self-sealing tubes evaluated.

We want to note an operation that presents a specific hazard above and beyond the hazards discussed above associated with the use of the NCCLS microhematocrit method. This hazard is the practice of plasma harvesting, prescribed and codified as a standard operating procedure at plasmapheresis centers. Workers at the donor collection sites at the plasmapheresis centers routinely perform a refractometric protein analysis by scoring (filing a scratch) between the packed cells and the end of the capillary tube containing plasma, followed by breaking the tube with the hands. The segment containing the plasma is then tapped onto the glass surface of the refractometer in order to drain the plasma from the broken capillary tube; hence, the term "plasma harvesting". Often splintering capillary tubes with consequent direct blood exposure or even bloody skin punctures and aerosolization of blood, is practically eliminated when using self-sealing capillary tubes and the dispenser. The use of the dispenser to directly expel plasma from the tube is an important additional engineering control for a significant albeit "less wide" spread encounter with capillary tubes.

Analysis of the economics of the self-sealing capillary tube discloses that when the overall cost to determine PCVs by the NCCLS Approved Standard microhematocrit method are calculated, it is found that the reduction in handling time required to seal the blood-filled capillary tube offsets the increase cost of the self-sealing capillary tube relative to the cost of the conventional capillary tube.

Moreover, when accounting is also made for materials, labor, and time associated with repeat testing needed by "blow-outs", is also clear that overall costs of using the self-sealing capillary tubes are somewhat less than using the conventional tube.

We have identified a significant bloodborne hazard previously overlooked by everyone excepting the healthcare workers themselves, who determine the Packed Cell Volume by the NCCLS Approved Standard Microhematocrit Method. However, we are now able to provide a unique engineering control that greatly reduces bloodborne infection hazards and at the same time, is user efficient, cost effective, and available.

OSHA can encourage the development of engineering controls by requiring their use under the proposed standards when they can be demonstrated to be effective, economical and readily available.