Blood is a tissue that is made up of 80% liquid and 20% cells.  The liquid portion is called plasma and contains water, proteins, fats, sugars and salt.  The solids which are suspended in the plasma are red blood cells, white blood cells and platelets.  These cells develop in the bone marrow from haematopoietic stem cells and become differentiated into the different types of cells.  Stem cells can be found circulating in the blood, as well as in the umbilical cord of newborn babies.  The plasma acts as a transport medium taking the cells, electrolytes, nutrients, hormones, waste products and antibodies throughout the body.  

The blood carries oxygen via the red blood cells from the lungs to other parts of the body and collects carbon dioxide to be returned to the lungs for removal from the body.  The red cells give the blood the appearance of being red.  

The white blood cells in the blood are responsible for protecting the body from infection.  The neutrophils, T-lymphocytes and B-lymphocytes are all types of white blood cells and have different functions.  The B-lymphocyte is responsible for making the antibodies which defend the body from bacteria, viruses (such as COVID-19) and other invading materials. 

The platelets are actually fragments of cells which migrate to the point of an injury to form a clot and prevent loss of blood.   Excess platelets can lead to more clotting than necessary and put the person at risk of heart attack and strokes.  

There are different types of blood, namely A, B, AB, and O. These types are inherited from our parents and are important to safe blood transfusion.  The blood types of both the donor and the recipient need to be compatible.  Persons with Type O blood are called Universal Donors as they can give blood to any other group while only being able to receive blood from persons with Type O blood.   

These blood groups are not the only determinants of matching a donor with a recipient.  There are markers or antigens on the red blood cells that further typify blood and some of them are rare.  The process of identifying a match is called “group and cross-match”.  Some blood types are found only in some racial and ethnic groups making it important to get donations from a wide variety of persons.   

Blood donation

The average male has 8-10 pints of blood while females have 8-9 pints of blood.   In situations of severe blood loss, there may be a need for replacement using a blood transfusion.  A blood donor can give one pint of blood without having any ill effects.  The body replaces the fluid within a few days and within 2-4 weeks the red blood cells are replaced.  In some countries, the donor may give only one component of the blood e. g. platelets and the other components are returned to the body at the time of making the donation.   In Jamaica, donations of whole blood are made, and the blood is subsequently separated into its components according to demand.  One pint of blood can therefore be used for more than one person.  Blood is given to patients with burns, sickle cell, traumatic injuries, cancers, some chronic diseases and in childbirth.  In Jamaica, pregnant mothers are asked to have a pint of blood donated for them before they give birth as there is a risk of significant blood loss during or after delivery.      

How do you donate blood?

Persons who donate blood need to be healthy, over the age of 18 years and weigh 110lbs or more.  In preparation for donation, there is an interview in which health and travel histories are taken and the donor’s haemoglobin or blood count is checked.  The person’s blood pressure, pulse and temperature are also checked.  It is advisable to get a good night’s sleep the night before and to hydrate with lots of water or any non-alcoholic drink before and after the pint of blood is donated.   The donor should have a non-fatty meal before giving blood.   The entire process from interview to departure will take about one hour with 10-15 minutes being the actual time for the collection of blood.  Note should be taken that all the equipment used are sterile and used only once.  The donor is given a drink and allowed to relax prior to leaving the collection site.   A regular blood donor can give a pint 4-5 times a year. This donation is from the goodness of the donor’s heart as there is no monetary compensation. 

Who may not give blood?

• Non-prescription injected drug users.
• Males who have had sexual intercourse with males within the prior 3 months. 
• Someone who has tested positive for HIV.
• Someone who has exchanged sex for money or drugs within the prior 3 months.
• Anyone born with a bleeding disorder.
• Persons taking certain medications or who have certain conditions as determined by the medical interviewer.

COVID-19 considerations

Persons who have tested positive for COVID-19 would need to wait a fourteen (14) day period before donating blood.  If the donor has received a RNA-based COVID-19 vaccine or a non-replicated inactivated vaccine manufactured by Janssen/J&J, Pfizer, Moderna, Astra Zeneca or Novavax, the donor does not have to wait for any period before giving blood.  

All safety precautions are observed at the blood collecting centres and potential donors should continue to wear their masks, sanitize their hands and maintain some distance between themselves and others. 

Blood Collection Centres

There are 10 collection centres located in Montego Bay, Falmouth, Kingston, St. Ann’s Bay, Mandeville, May Pen, Port Antonio and Savanna-la-mar.  All sites are listed online together with the opening times.

“GIVE BLOOD AND SAVE A LIFE.”

 Prepared by Donna McKoy RN, RPh, MPH

References

https://www.texasheart.org/heart-health/heart-information-center/topics/blood/ accessed June 4, 2021

https://www.hematology.org/education/patients/blood-basics accessed June 4, 2021.

https://www.mayoclinic.org/tests-procedures/blood-donation/about/pac-20385144 accessed June 7, 2021.

https://www.redcrossblood.org/local-homepage/news/article/covid-19-vaccination-guide-blood-donation.html  accessed June 10, 2021