EPISODE 04 - INTERNSHIP DIARIES (What will I do with your blood? -Vials and sampling)

- By Upasana and Jay

It has been a tired day at the hospital. You are almost at the end of your day of duty when your senior resident asks you,

“Dr Kesh, can you please prepare the Laboratory forms, sign them for me and then, submit these blood samples to the Main laboratory?

“Yes sir!” You pressure a smile and look at the blood samples and the empty Laboratory request forms needing your signature and your gleaming new stamp with your licence number.

You sit down to prepare the blood samples.

******************************************************

(Lesson 2)

There are 3 types of blood we use for different purpose:-

1. Capillary blood
2. Arterial blood
3. Venous blood

WHEN DO WE NEED CAPILLARY BLOOD?

Often drawn as a small amount of blood in a microtubule. Often used a sterile needle to puncture the skin of the fingers, toes or sole(esp for an infant)

• Strip for blood sugar meter also called Glucometer.
• Bleeding time tests
• For infants and young children 

WHEN DO WE NEED ARTERIAL BLOOD?

• Specially required for estimation of the blood gases ABG(Arterial Blood Gas) ,PH,PCO2 and PO2.
• Collects quickly,and fills completely due to the arterial pressure.
• Always mention Spo2 of the patient measured by pulse oximeter.

  

WHEN DO WE NEED VENOUS BLOOD?

• MOST COMMONLY USED METHOD
• Majority of routine tests are performed on venous blood.
• The best site -deep veins of antecubital fossa. 

IMPORTANT - DO NOT TAKE BLOOD FROM HAND WITH VENOUS INFUSION,THIS LEADS TO FALSE RESULT DUE TO DILUTION OR ADDITION . TAKE THE SAMPLE FROM THE OPPOSITE HAND OR A FOOT.

SUPPOSE WE ARE GIVING GLUCOSE DRIP AND YOU TAKE SAMPLE FROM THAT HAND. THE BLOOD GLUCOSE COULD COME OUT AS 600mg/dL DESPITE HE BEING NOT DIABETIC WHICH WOULD LEAD YOU FOR A MISDIAGNOSIS AND YOU MIGHT END UP GIVINIG HIM INSULIN.

Note that in Pediatric Patients, the vial sizes could be smaller and the blood needed will be a smaller amount as well, often amounting to 1ml for infants and toddlers.

SERUM:-

Liquid remaining after blood has clotted naturally in a plain tube.

It is the most common specimen required for chemical and serological test.

PLASMA:-

A fluid obtained from anticoagulated and centrifuged blood.

it is required for coagulation profile and fibrinogen assay.

FOLLOWING THINGS WE ALL SHOULD KNOW ABOUT THE CAPS OF THE VIALS:-

LAVENDER CAP - Most commonly used. Contains EDTA. Used for Routine blood tests like Hb,TLC,PS,ESR determination by Wintrobes method.

GREY CAP- Contains sodium fluoride. Used for blood sugar estimation.

BLUE CAP- Contains citrate as an anticoagulant so we used for coagulation tests and ESR by wetergreens method

DARK GREEN CAP - contains heparin so used for ABG analysis,Osmotic fragility tests and immunophenotyping.

LIGHT GREEN CAP - for plasma determinations.

PINK CAP-is similar to purple but used for blood banking.

RED AND YELLOW CAPS -CONTAINS NO ADDITIVES and are used for serum studies.

Cap Colours of Vials

The ratio of anticoagulant and blood. :

1. Sodium citrate 

• in blue tube :- 1:9 
• in black tube :-1:4

2. Heparin Dark green tube:- 0.5 to 1 mg per 5 ml of blood.

• HOW MANY TIMES YOU HAVE TO INVERT TUBE TO MIX THE BLOOD WELL?

-          8-10 TIMES.

THINGS YOU SHOULD THINK BEFORE TAKING OUT ANY SAMPLE :

1.  Identify the patient (Name, age and sex). Certain parameters are different according to age and sex of the patient.
2. See the provisional/working/admitting diagnosis
3. Site of collection
4. Time of collection of sample
5. Your expectations with this sample in leading you to diagnosis hence helping to select the vial.

At the end of collection make sure you always write the 

• Name of the patient 
• The sample and test 
• The date and time
• Optionally the name of the Doctor who ordered.

********************************************************

You finally finish your lab requests, sign them, stamp them and send to the laboratory, and stand up to go home!

It had been a tiring day saving lives! You deserve a nice meal and a good night’s sleep! You walk out of the halls of the San Jose General Hospital, with a sigh of relief!

********************************************************

Main Author : Upasana Yadav

Co- Author : Jay