Latest trends in blood transfusion
Dr J.G. Jolly

The safety of the blood transfusion practice begins with the type of donation available. A firm resolve to depend entirely on voluntary blood donors is essential for maintaining the safety of blood and blood components. It is equally important to strictly adhere to the criterion of donor selection, and only those who fulfil the minimum requirements should be entertained.

For this, any healthy volunteer between the age group of 18 and 60 years, weighing above 50 kg, free from disease, especially transmissible infections such as AIDS, hepatitis, syphilis and malaria, can safely donate 400 ML of blood after every three months.

The practice of dependence on professional blood sellers is unethical and technically hazardous. Thus, for ensuring safe blood, total dependence on voluntary donors and complete elimination of professional blood sellers is of paramount importance.

The availability of improved blood containers, blood plastic bags instead of glass bottles and preservative anti-coagulant solutions have helped in better processing techniques and thus the storage period has been increased from 20 days to 49 days. While preservative solution ACD has a shelf life of 21 days, CPDA1 and ADSOL have a shelf life of 35 and 49 days respectively.

In fact, frozen blood can be stored for three to 10 years. This is possible by the addition of cryo-protective agents like glycerol to blood collected in a standard anti-coagulant and freezing the same at ultra-low temperature, below minus 65°C. Whereas the whole blood and packed cells are stored in a refrigerator at 4°C, platelets are stored at room temperature, and the coagulation factors like cryoprecipitate and fresh frozen plasma are stored in a deep freeze below minus 20°C.

Blood components

The transfusion practice, based primarily on the use of whole blood, has now been replaced by a substitution therapy or blood component therapy. In this case the patient is administered only that constituent in which he or she is deficient. By this the patient gets the maximum benefit at the minimum risk and the components thus saved are conserved for other patients. Modern technology for blood collection in double, triple or quadruple plastic bags has made it possible to utilise single donor’s blood for several patients suffering from different diseases. For instance, by using a triple bag an anaemic patient receives red cells and another one suffering from platelet deficiency receives platelet concentrate.

The plasma, after the separation of the coagulation factor for a hemophiliac patient, can be utilised for the preparation of other blood fractions. Temperature regulation and speed of centrifugation play an important role in the preparation of components. Whereas the preparation of coagulation factors require low temperature, i.e. below 4°C, the functional efficiency of platelets is best maintained at room temperature, i.e. 22°C.

For platelets, the refrigerated temperature will result in aggregation and loss of functional utility. The term blood components include various parts of blood that are separated by conventional technology like centrifugation, freezing, thawing, etc, or by cell separator machines. When more sophisticated or chemical manufacturing processes are involved, the final product is termed as fraction or plasma derivatives.

A routine blood bank equipped with a refrigerated centrifuge, freezer, refrigerated water bath, refrigerator and plastic bags, can prepare all the components. The most frequently used component consists of packed red blood cells and can be prepared by expressing the plasma from whole blood in which the red cells have been allowed to settle. Another component that is prepared frequently is platelet concentrate. Platelets must be separated from whole blood immediately after collection and constantly agitated during the storage at 22°C to prevent aggregation.

The plasma recovered as a result of preparation of packed cells and platelets may be frozen quickly and stored up to one year at minus 30°C, as a source of Factor VIII and other coagulation factors. Such plasma is popularly known as fresh frozen plasma (FFP). Cryoprecipitate is prepared after freezing the plasma, and thawing it at 4°C makes it an even richer source of Factor VIII. This can be removed and preserved, after which the remaining material can be fractionated into albumin, gamma globulin and other fractions.

It has been emphasised that those engaged in transfusion therapy have the primary responsibility of ensuring the safety of the transfusion procedure and should receive adequate training. Whenever transfusion is requisitioned, it is incumbent on the attending consultant to ensure that it is absolutely essential. Proper planning is a must for the component required, its dosage and periodicity to achieve the objective for which it is being resorted.

It is, therefore, necessary that those prescribing transfusion should be familiar with all aspects of the transfusion set-up and the special care that is required for indication, shelf-life of various components, their storage and transport requirements to achieve the maximum benefit and safety.

The writer retired as a Professor from the PGI, Chandigarh.

Patience helps in winning the battle of the bulge
Dr Mahipal S. Sachdev

Intra-ocular lenses or IOLs are the artificial lenses that replace/ substitute the natural lens, which is removed during cataract surgery. Thick glasses after cataract surgery were a common thing in the days before the use of IOLs. IOLs gave independence from these glasses to the operated patients.

Fifty-five years ago when the first IOL was implanted in the human eye, a revolution started in the field of ophthalmology. Since then we have come a long way in developing newer generation IOLs keeping pace with the advancements in the cataract surgery procedures like phaco-emulsification.

The current technology for cataract surgery involves the procedure of phaco-emulsification with the implantation of an IOL which is either non-foldable or foldable. A lot of development has taken place as far as material and design of the IOL is concerned. This has helped in getting better visual outcomes for cataract patients.

The lenses in common use evolved from non-foldable to foldable as cataract surgery became stitchless. The most common lens implant is a single power or "monofocal" lens. Monofocal lenses have a 20-year track record of safety and satisfaction. Patients usually obtain clear glass-free vision at one "working distance" and require glasses or contact lenses to function at other viewing distance. We can often control where the working distance of the unaided eye will fall after surgery. If you and your surgeon choose a monofocal lens you will be asked to choose a "target" working distance, at which your eye undergoing surgery should have good "uncorrected" vision. While your particular choices may be limited by condition of the other eye, in general the choices include the following:

Monofocal Near - It is good for reading fine print and doing crafts. Patients will need glasses to see distant objects, to drive, play golf and other social activities. Usually, it is less preferred as one needs to look at a long distance for longer hours as compared to near work.

Monofocal Intermediate — It gives good vision at arms length for cooking, desk work, computer screens and some social activities. Usually, one can read large print uncorrected but needs glasses for fine print and driving.

Monofocal Far — It is good for driving without glasses and many sports. One always needs reading/ computer glasses for near work. It is preferred
routinely.

Monovision — Patients with cataract in both eyes have the freedom to achieve good glass-free near and far vision with monofocal implants by selecting one eye for distance vision and one eye for near. This strategy is called "monovision". Patients with monovision are less dependent on glasses than those with both eyes focused at the same working distance. Monovision patients experience less glare and better contrast sensitivity than those with multifocal lenses. The disadvantage of monovision is a reduction in depth perception, and some individuals feel that one eye is blurred without glasses.

Bifocal Lens Implants — If you have cataract in both eyes and little astigmatism, you might be a candidate for a bifocal lens implant. This lens typically provides simultaneous near and far vision without glasses. Patients with this lens experience somewhat more glare after surgery than the monofocal lenses, but typically gain the ability to see both near and far without glasses, e.g. Technis Bifocal IOL

Multifocal IOLs — The development of multifocal IOLs is a major technology jump as it has made possible for a cataract patient to have both long-distance vision and near vision after cataract surgery. This would help eliminate the need for glasses or reduce the dependence on glasses in some cases.

These IOLs work in a manner that at any given time when one focus is being used, the other focus becomes so blurred that it becomes imperceptible. Therefore, at any given time, the brain visualises only one image either for distance or for near.

The multifocal IOLs available today include ReZoom IOLs, Array Multifocal and Acrysof ReSTOR

However, in a very small population of cataract patients (5 per cent), the pre-existing structure of the eye produces some refractive error like cylindrical number, which is not corrected by these lenses. Therefore, a person may feel more comfortable with the use of the appropriate cylindrical power occasionally in order to get sharper vision. So, this technology essentially speaks of reduced dependence on glasses. Another factor of concern is the night-time halos.

These IOLs would offer a very viable choice to those patients who have been facing such problems in their active professional and home life. There are many more advances coming up in the IOLs.

These new generation IOLs unfold a plethora of lifestyle changes. Imagine the plight a 50-year-old patient, operated for cataract, who takes his guest to a restaurant and when he starts reading the menu he realises that he has forgotten his reading glasses at home.

With these IOLs, one can make such complaints history!

The writer is Chairman and Medical Director, Centre for Sight, New Delhi. E-mail: msachdev@bol.net.in.

Cancer: new developments
Dr J.D. Wig

Cancer continues to be a major public health problem. The worldwide mortality from human cancer remains unacceptably high despite advances in early detection and in the use of chemotherapy, radiotherapy and surgery.

Computerised axial tomography (CT) and magnetic resonance imaging have helped in diagnosis. The latest development in diagnosis is positron emission tomography (PET). PET essentially shows abnormality in the cell. A combination of PET-CT in one machine helps in showing the exact site of abnormality.

Endoscopic ultrasonography (EUS) is now firmly established as an investigation of choice in the diagnosis, staging and management of a wide range of cancers — gastrointestinal and lung cancers. The ability of EUS to acquire tissue safely results in a potential role of molecular diagnosis to enhance the performance of EUS-guided fine needle aspiration in providing a diagnosis.

Targeted chemotherapy: Cancers are often treated by surgery, which is frequently followed by adjunct radiation or chemotherapy. The problem with these adjunct therapies is the non-specific damage to healthy tissue. Furthermore, because cancer therapeutics are commonly delivered through the blood, only a small fraction of the drug reaches the target tumour. Thus, in order to obtain therapeutic effect, a relatively high dose of drug must be administered.

Much effort has been recently devoted to making anti-cancer drugs more tumour-specific. Targeted cancer therapies use drugs that block the growth and spread of cancer. They interfere with specific molecules involved in carcinogenesis (the process by which normal cells become cancer cells) and tumour growth. By focusing on molecular and cellular changes that are specific to cancer, targeted cancer therapies may be more effective than current treatment protocols and less harmful to normal cells. One approach is to “aim” the drug by placing “tags” to direct the chemotherapeutic selectively to the cancer cells. A second approach is to encapsulate the chemotherapeutic, so that it can persist longer in the circulation and not be immediately removed by the liver or kidneys.

Even though the whole body is given the chemical, normal cells remain intact, only the cancerous cells are killed, hence targeted therapy’s acceptance is growing rapidly. These new advances in therapy hold the promises of being more selective, harming fewer normal cells, reducing side-effects and working to improve the quality of life for people with cancer.

Nanotechnology: Building tools smaller than cells could radically change cancer diagnosis and treatment. The size of a nanometer is one-billionth of a meter or roughly 10 times the size of an individuals atom. Scientists and engineers are building tools, machines and even entire systems the size of nanometers, so small that they can fit inside a single cell. The pace of nanotechnology is moving so quickly, in the next 10 to 15 years , that “nano” tools could allow us to identify and destroy cancer cells at the earliest stages of development. Devices that are small enough to fit inside the nucleus of a cell could be used to detect cancer long before a physical examination or an imaging study.

High-dose rate brachytherapy: Brachytherapy delivers a protected source of radiation directly inside the body to destroy cancer cells. With high dose rate brachytherapy, very high energy radiation can be delivered through a catheter, directly to the surface of the tumour inside the tumour or into a body cavity that surrounds the tumour. Specially designed computers and CT scanners are used to plan the radiation doses precisely to conform to the size and shape.

Intensive modulated radiation therapy: The maximum amount of radiation can be given to the cancerous tissue without affecting the normal tissue. Advanced technology enables the radiation machine to turn and rotate.

Radiosurgery is a form of bloodless surgery using micro-multi-collinators. The tumour can be located using the computer, and radiation is given to the tumour only.

Vaccinative strategies: Remarkable advances in molecular immunology and biotechnology have created a unique opportunity for developing active vaccination strategies that engage the patient’s own immune system in the fight against cancer.

Epigenetic therapies: Epigenetics is the study of chromation modifications that affect gene expression without altering DNA nucleotide sequences. When used in combination with conventional chemotherapeutic agents, epigenetic-based therapies may provide a means to resensitise drug-resistant tumours to the established treatments.

The writer is Professor and Head, Department of General Surgery, PGI, Chandigarh.

Threats from uncontrolled high BP

WASHINGTON: A new study published in the current issue of Neuropsychology has shown that uncontrolled high blood pressure is linked to more cognitive problems in old age.

According to the study, uncontrolled hypertension puts people at higher risk for sharper drops in cognitive functions than does blood pressure that’s normal due to diet, exercise or medication. Because blood pressure typically increases with age, hypertension affects 60 per cent of adults aged 60 and older.

However, this “silent killer” often goes undetected or inadequately treated, leaving nearly 40 per cent of older hypertensive people with continued high readings — even with treatment. As a result, the findings suggest that a substantial number of older people with uncontrolled hypertension will experience significant cognitive declines, especially because with age, hypertension becomes more common and harder to control.

Researchers at the Veterans Affairs (VA) Boston Healthcare System, Harvard Medical School and the Boston University School of Public Health looked at a subset of men in the VA Normative Aging Study, a longitudinal study that started in 1963 and added neuropsychological tests in 1993.

In this smaller cross-sectional study, 357 men from the larger sample averaged 67 years of age, lived in the community, didn’t have dementia or other serious medical problems, and showed stable blood pressure over a three-year interval. — ANI