capillary puncture

• Capillary Puncture

  The method of choice in children under one year old and for adults whose veins are inaccessible
• Capillary Puncture

  • The blood in the capillary bed is predominantly arterials
  • The test result from the predominantly arterial capillary blood is generally acceptable as a substitute for venous blood

  
• Capillary Puncture in Adults

  Done in the ring or middle finger
• Capillary Puncture in Children <1yo

  Done in the foot
• Capillary Blood

  A mixture of venous and arterial blood, but is predominantly arterial blood
• Materials for Capillary Puncture

  • Lancet
  • Sealing Clay
  • Microtainer
  • Capillary tubes
  • Cotton balls/GAUZE
  • 70% isopropranol /tincture of iodine
  • Adhesive bandage / micropore
• Indicators for Capillary Puncture

  • Severely burned patients
  • Cancer patients whose veins are reserved for therapeutic purposes
  • Obese patients
  • Geriatric patients
  • POCT
  • Malarial smears
• Less Capillary Blood Obtained When

  • Patient is dehydrated
  • Patient has poor blood circulation
  • Patient is stressed
  • Cold environment
• Warming to Increase Capillary Blood Flow

  1. Warm washcloth is used

  2. About 42˚C

  3. Wrap hand for about 3-5 mins

  4. Warming can increase the capillary blood flow as much as 7x

  5. Massaging the patients finger may be done as an alternative
• Sites for Capillary Puncture

  1. Infant heel: lateral aspect of the plantar surface

  2. Middle or ring finger: center of the finger

  3. Avoid puncturing the tip or the side because the tissue is about half as thick at the center

  4. Do not obtain capillary blood from an edematous site

  5. Puncture perpendicular to the finger print to obtain a drop of blood easier
• Capillary Puncture Technique

  • The blade is about 2 mm long
  • Any deeper, the blade may hit the patients bone, especially if the patient is an infant
  • Do not press the lancet too hard
  • A cut made too shallow will not yield enough sample
• Capillary Puncture Procedure

  1. The first drop of blood is discarded

  2. If puncture is adequate, 0.5 ml of blood is obtained

  3. Gently apply continuous pressure to the area around the puncture to enhance blood flow: do not milk the site

  4. Collect the sample in a micro collection device

  5. Follow the appropriate amount of inversions based on the additive

  6. Avoid scraping blood off the skin

  7. Allow capillary blood to flow freely from the containers tip, to the side of the micro collection tube

  
• Order of Draw

  • BLOOD GASSES
  • SLIDES 3
  • LAVANDER STOPPERED MICROCOLLECTION TUBES
  • GREEN STOPPERED MICROCOLLECTION TUBES
  • OTHER ADDITIVE MICROCOLLECTION TUBE
  • RED STOPPERED MICROCOLLECTION TUBE
• Povidone iodine increases aspirin acid
• The first wipe contains contamination of tissue fluid
• Blade length: 0.85mm for premature, 2mm for full infants, 5mm for adults
• Bleeding Time

  A laboratory test to assess platelet function and the body's ability to form a clot. The test involves making a puncture wound in a superficial area of the skin and monitoring the time needed for bleeding to stop
• Bleeding Time

  • Measures the functional integrity of the small vessels and the ability of platelets to form hemostatic plugs to stop bleeding
  • Dependent upon efficiency of tissue fluid in accelerating coagulation process, capillary function, number of platelets present, ability to form platelet plug
• Ivy's Method for Bleeding Time

  1. Place a blood pressure cuff on the upper arm and inflate to 40 mmHg

  2. Apply antiseptic into the intended site in an inside to outward circular motion

  3. Use a disposable lancet to make two separate cuts into the forearm usually 5-10cm apart in quick succession

  4. Start a stopwatch immediately and every 30 seconds filter paper is used to draw off the blood

  5. The time from when the incision is made until all bleeding has stopped is called the bleeding time

  6. The test is finished when bleeding has stopped completely
• Bleeding Time Reference Range

  The reference range is between 2- 7 minutes. In cases in which the BT exceeds 20 minutes it is usual to stop at 20 minutes and report the BT as >20minutes
• Sources of Error for Bleeding Time

  • Administration of blood thinners
  • Residual alcohol
  • Improperly performed procedure
  • Too shallow
  • Too deep
• Bleeding Time Quality Control

  • Accomplished through standardization of procedure
  • Wound is of standard length and depth
  • Constant pressure of 40 mmHg should be maintained throughout the procedure
• Clotting Time

  The time required for a sample of blood to coagulate in vitro under standard conditions
• Lee and White Method for Clotting Time

  1. After cleaning the forearm, make a venipuncture to draw 3 ml of blood

  2. Start the stopwatch

  3. Transfer 1 ml of blood each into 3 glass tubes and incubate at 37° C in a water bath

  4. After 5 minutes tilt the tubes one by one every 30 seconds

  5. The clotting time is taken when the tubes can be tilted without spilling of their contents

  6. Calculate the clotting time by average of 3 tubes
• Lee and White Clotting Time Method

  • More accurate and standard method
  • Test can be run with control
• Disadvantages of Lee and White Clotting Time Method

  • It is also a rough method
  • There can be contamination of syringe or tube
  • The temperature should be maintained because higher temperature accelerates clotting
  • The diameter of the glass tubes should be uniform because clotting is accelerated in narrow tubes
  • Vigorous agitation of the tubes should be avoided as it shortens the clotting time
• Clotting Time Reference Range

  Normal clotting time is 5-10 minutes
• Conditions that Prolong Clotting Time

  • Severe deficiency of coagulation factors
  • Afibrinogenemia
  • Administration of heparin
  • Disseminated intravascular coagulation (DIC)
  • Administration of drugs such as anticoagulants
• Capillary Tube Method for Clotting Time

  1. Clean the tip of a finger with 70% isopropanol

  2. Puncture it up to 3 mm deep with a disposable lancet

  3. Start the stopwatch

  4. Wipe the first drop of blood

  5. Fill two capillary tubes with free flowing blood form the puncture

  6. Keep these tubes at body temperature

  7. After 2 minutes, start breaking the capillary tube at 1 cm distance to see whether a thin fibrin stand is formed between the two broken ends

  8. Stop the watch and calculate the time from average of the two capillary tubes

  
• Capillary Tube Clotting Time Method

  • Method is insensitive
  • Method is unreliable
  • Can be performed when venous blood cannot be obtained

  
• Capillary Tube Clotting Time Reference Range

  Normal clotting time is 1-5 minutes