Puzzle page

Blood products are commonly used in hospital and especially in theatre. Their use is not without risk and a good understanding of the subject is essential for safe practice. In the grid below, find terms relating to blood transfusion by moving from letter to adjacent letter.

Although whole blood is collected from donors, it is no longer transfused into patients. Instead, blood is separated into its component parts and these parts are issued as needed.

Blood products
Red cell products These are given as packed red blood cells that are spun down and then resuspended in an artificial solution that is designed to keep them in optimal condition for as long as possible. This solution contains saline, adenine and glucose (SAG). Each unit contains approximately 300 mL with a haematocrit concentration of 50-70%. One unit of packed red blood cells will usually increase the haemoglobin level by approximately 1 g. Packed red blood cells have to be crossmatched before use. Universal donor, O-negative blood can be used in emergency situations.

Clotting factors
Clotting factors are available as fresh frozen plasma (FFP), which has to be thawed before use. FFP contains all the normal levels of clotting factors and is used to correct clotting abnormalities. The normal dose is 10-15 mL/kg. Cryoprecipitate is derived from FFP, and contains large amounts of factor VIII and fibrinogen.

Platelet concentrations
These can be taken from an individual or, more often, pooled from four to six donors. They are given via a special giving set.

Risks of blood transfusion
There are a number of risks associated with the transfusion of any blood product. These include the following.

Acute transfusion reaction with haemolysis
This is an acute severe response to ABO-incompatible blood. It occurs in approximately 1 in 500,000 red cell units transfused, and is most commonly caused by clerical error whilst taking blood for crossmatching or administering blood. Mortality is 10%.

Infective shock
This is due to bacterial contamination of transfused blood. The occurrence is 2 per million transfused blood components. Mortality is very high.

Transfusion-related acute lung injury (TRALI)
This occurs when the donor plasma contains antibodies to the patient’s leukocytes. The risk is greater if large volumes of donor plasma are administered. Mortality is high.

Nonhaemolytic febrile reactions
These are caused by antibodies to transfused white cells. The incidence is less with leukocyte-depleted red cells. It is unpleasant, but not life-threatening.

Transmission of infection
Donor units are screened for HIV, hepatitis B, hepatitis C and syphilis. The risk of transmission of these and other infections is now extremely low.

Fluid overload
This can be a problem if large volumes of blood are given quickly. BR>


Airway erquipment

All patients under anaesthesia and many patients who are unconscious will lose their airway or 'swallow their tongue.' Anaesthetists spend a lot of their time managing and protecting patients' airways and have various items to help them.

Join the dots to reveal items of airway equipment. Can you name them and state how they are used?

Mask
This most basic piece of airway kit is essential unless you want to do mouth to mouth! Masks come in various sizes and in clear and black rubber versions. You can even get strawberry-smelling ones for paediatrics. They will not maintain an airway by themselves - you still need to perform basic airway manoeuvres to open the airway, such as a chin lift and head tilt or jaw thrust.

Guedel/oropharyngeal airway
As the name suggests, this sits in the oropharynx and provides a patent airway by holding the tongue and soft tissues forward. It comes in different sizes. Find the right size by measuring the distance between the corner of the patient’s mouth and the tragus of their ear. It does not protect against aspiration or regurgitation. The Guedel airway should be inserted upside down and rotated into position. The patient must be unconscious to tolerate this - it can induce vomiting in a patient who is too awake.

Nasopharyngeal airway
This sits in the nasopharynx and opens the airway. Again, it comes in various sizes. Size by comparing it with the size of the patient’s little finger. The nasopharyngeal airway does not prevent against aspiration or regurgitation, but can be tolerated by more awake patients (useful in A&E). It is inserted by gently pushing straight back down a nostril (not straight up into the brain!). Avoid in patients with a head injury (potential base of skull fracture). You must use the nasopharyngeal airway with the supplied safety pin through the end of the airway to prevent it disappearing down the nose and into the trachea. Do not put the safety pin through the patient’s nose (this has been done!).

Laryngeal mask airway
This is the next stage up from a mask. The patient has to be unconscious or anaesthetised to tolerate it. Basically, it is a mask that sits on the larynx and maintains the airway. It allows spontaneous breathing and ventilation, but does not protect the airway from aspiration. It comes in sizes 3, 4 and 5 for adults.This equipment has been suggested for use at cardiac arrests when an anaesthetist is not available. It is very easy to insert.

Endotracheal tube
This is the definitive airway. The endotracheal tube is inserted directly into the trachea, usually under direct vision with a laryngoscope. A cuff secures the airway from aspiration. It is available in a range of sizes (adult 7-9), which refer to the internal diameter of the tube. This equipment allows positive pressure ventilation. The patient must be deeply unconscious or anaesthetised and is often paralysed to aid insertion.

Acknowledgement

Taken from the forthcoming Puzzling Out... series by Remedica Publishing. For more information or to claim your StudentBMJ discount, call Rachel on
020 7554 0741 or contact books@remedica.com.



studentBMJ 2004;12:309-348 SeptemberISSN 0966-6494