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Voluntary Blood Donation - Understanding the science behind the good deed!

Why do we need to donate blood?

Blood is a complex mixture consisting of numerous cells suspended in a fluid called plasma.

Red blood cells (RBC) which contain a pigment called hemoglobin that gives the red colour to blood. The oxygen that you breathe in through your lungs is carried to all parts of your body through these RBCs.

White blood cells (WBC) which are responsible to fight against germs and provide you with immunity.

Platelets that help in clotting whenever there is a cut/ tear in the blood vessels

All these cells are suspended in a straw coloured watery fluid called plasma, rich in electrolytes (sodium, potassium, magnesium, calcium etc), hormones, immunoglobulins(proteins enhance immunity), clotting factors, water and other metabolic substances.

Unfortunately medical science has not been able to find a way to make human blood artificially. There are fluids like saline, dextrose, ringer’s lactate solution etc that can be given temporarily to increase the blood volume but there is no artificial substitute to human blood !

What happens to the blood that is donated?

Irrespective of the health of the donor, every unit of blood is carefully screened for approximately 5-7 major blood borne diseases to ensure safety. The blood group is confirmed. Once it is found to be safe, each unit of donated blood is separated into components such as RBCs, platelet concentrates, cryoprecipitates and fresh frozen plasma so that it could benefit more than a single patient. On an average, every time you donate blood you could be helping 3-5 patients in need!

All the components are carefully catalogued and stored under required temperature for use in an emergency. Whole blood can be stored for around 42 days and blood components for 3-4 days under strict temperature control.

If the donated blood tests positive for any disease, it is immediately discarded in a safe manner and the donor is notified. The details of this are kept strictly confidential and only notified to the donor directly.

Who benefits from the blood donation?

Millions of patients across the country require blood and blood products every day. Some situations where blood transfusion is crucial are:

- Road traffic accidents/ major injuries with lot of blood loss

- Those undergoing major surgeries

- Excess blood loss during child birth

- Patients suffering from severe anaemia

- Blood disorders, cancer treatments

- Babies/children with inherited blood disorders

- Patients of certain infectious diseases like dengue fever, malaria etc

Who can donate blood?

Any healthy adult in the age group of 18 – 60 yr can donate blood. Those above 60 yr are advised to consult their doctor before deciding to donate blood.

Who should not donate blood?*

  • People on aspirin or other medications that affect blood clotting, antibiotics, steroids or hormonal therapy

  • Those who have had a vaccination within the past 3 months

  • Those who have uncontrolled diabetes, hypertension or other chronic diseases

  • Those with low hemoglobin (<12.5 gm /dl)

  • Those with kidney disease, liver or heart disease, heart surgery in the past.

  • Severe alcoholics or an alcohol binge in past 24 hr. Occasional/social drinkers can donate. It is advisable to abstain from alcohol 24hr prior to donation

  • Those who have had a major surgery or major blood loss within past 6 months

  • Those with any ongoing illness like fever, cold, flu etc.

  • Those who have had malaria in the past

  • Pregnant women, recent pregnancy or miscarriage within past 6 months. (Lactating women can donate provided it has been 6 months past their pregnancy and they are otherwise healthy with normal hemoglobin.)

  • Those who have donated blood within past 3 months.

  • Those with HIV, Hepatitis B or other blood borne diseases, recreational drug users.

  • Smokers can donate blood if they are otherwise healthy. It is advisable to avoid smoking atleast 12 hours prior to and after donation

*Common cases where blood donation is not advised are included here. If you have any specific conditions that you are doubtful about, speak to your family doctor.

Your blood donation appointment – What to expect?

  1. The doctor/ nurse will register your details, take a medical history and do a quick examination to ensure you are a right candidate for blood donation.

  2. You will be asked to lie down and the nurse will clean the site on your forearm with antiseptic and prick your vein to insert an intravenous (IV) cannula. This may cause some momentary discomfort or soreness.

  3. This cannula will be connected by a tube to the collection packet that is placed at a lower level.

  4. You may be asked to pump your fists or given a soft toy to press so that the blood flow is continuous

  5. A blood pressure cuff tied above the cannula gives continuous pressure to the blood flow.

  6. If the IV cannula is inserted properly and is in place, you will not experience any pain when the blood flows out.

7. You can relax now as the blood is collected. It may take between 20-30 min.

8. Around 450 – 500ml of blood may be collected. Once it is done, the nurse will remove the tube and cannula and put on a bandaid on the IV site. It may be a bit sore for a few days. You can take this as a reminder of your good deed!

9. Usually blood donation does not cause any after effects. The blood volume that you donate is replenished within 1-2 days and all the cells within 2-6 weeks of donation. Yet some people may experience some light headedness during or just after donation, especially those who are nervous or squeamish about blood. This is usually nothing serious and should pass if you hydrate well and just lie down for a while.

Tips for a safe and enriching blood donation experience

  • Have a restful night’s sleep on the previous day and drink atleast 2.5 -3 liters of water to keep well hydrated.

  • Avoid alcohol and smoking one day before and after donation

  • Make sure you don’t skip your breakfast on the day of your blood donation appointment. Eat a good meal with plenty of water.

  • Be honest with the doctor/nurse when he/she takes your medical history prior to donation. Discuss and clarify all your doubts and queries.

  • Calm your nerves during the blood collection time by listening to some music or browsing through a magazine.

  • Any time during the collection if you experience giddiness, palpitations, excess sweating or severe pain at the IV site, report to the doctor/nurse immediately

  • Avoid strenuous exercise, gym workouts 24hours after blood donation. Drink plenty of water (around 2-3 litres) on the day after donation.

Read about the common myths and misconceptions about blood donation in our next article!

We hope this post has given you a fair idea about blood donation and inspired you to donate!

References and further reading:

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