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B Appendix Measurement protocols
Text master (11/22) 1 Height and weight measurement 1.1 Eligibility You should be able to measure the height and weight of most of the informants. However, in some cases it may not be possible or appropriate to do so. Do not force the informant to be measured if it is clear that the measurement will be far from reliable but whenever you think a reasonable measurement can be taken do so. Examples of people who should not be measured are:
1.2 Site It is strongly preferable to measure height and weight on a floor which is level and not carpeted. If all the household is carpeted, choose a floor with the thinnest and hardest carpet (usually the kitchen or bathroom). 1.3 Height measurements The equipment Portable stadiometer - a collapsible device with a sliding head plate, a base plate and three contacting rods marked with a measuring scale. Frankfort plane card The protocol - adults (aged 16 and over)
The protocol - children (age 2-15) The protocol for measuring children differs slightly to that for adults. You must get the co-operation of an adult household member. You will need their assistance in order to carry out the protocol, and children are much more likely to be co-operative themselves if another household member is involved in the measurement. If possible measure children last so that they can see what is going on before they are measured themselves. Children's bodies are much more elastic than those of adults. Unlike adults they will need your help in order to stretch to their fullest height. This is done by stretching them. This is essential in order to get an accurate measurement. It causes no pain and simply helps support the child while they stretch to their tallest height. It is important that you practice these measurement techniques on any young children among your family or friends. The more practice you get before going into the field the better your technique will be.
Additional points - all informants
1.4 Weight measurements The equipment Soehnle electronic bathroom scales The scales have an inbuilt memory which stores the weight for 10 minutes. If during this time you weigh another object that differs in weight by less than 500 grams (about 1 lb), the stored weight will be displayed and not the weight that is being measured. This means that if you weigh someone else during this time, you could be given the wrong reading for the second person. So if you get an identical reading for a second person, make sure that the memory has been cleared. Clear the memory from the last reading by weighing an object that is more than 500 grams lighter (eg a pile of books, your briefcase or even the stadiometer). You will then get the correct weight when you weigh the second informant. You will only need to clear the memory in this way if:
The protocol
Weighing children You must get the co-operation of an adult household member. This will help the child to relax and children, especially small children are much more likely to be co-operative themselves if an adult known to them is involved in the procedure. Children wearing nappies should be wearing a dry disposable. If the nappy is wet, please ask the parent to change it for a dry one and explain that the wetness of the nappy will affect the weight measurement. In most cases it will be possible to measure children's weight following the protocol set out for adults. However, if accurate readings are to be obtained, it is very important that informants stand still. Ask the child to stand perfectly still - 'Be a statue'. If small children find this difficult you will need to alter the protocol and first weigh an adult then weigh that adult holding the child as follows:
The computer will then calculate the weight of the child and you will be asked to check that you have recorded the weight onto the child's Measurement Record Card at MBookWt. Again the computer will give the weight in both kilos and in stones and pounds. 2 Measurement of mid upper arm circumference 2.1 Purpose The mid upper arm circumference is a key indicator of the nutritional status of children, being reduced substantially in the undernourished and being substantially increased in children who are overweight. 2.2 Eligibility All informants from age two to age fifteen inclusive are to be measured. Exclude any child who is known to be pregnant. 2.3 Equipment You will be provided with a short tape. One end of this tape is broad and on it you will see the words READ HERE, with a small arrow. This is the start of the tape. You will first use this tape to measure the length of the arm and then, having found the mid point of the arm, you will measure the circumference of the arm. When measuring the circumference of the arm, the tape is threaded as indicated in the illustration below. Pull the tapered end up through slot 1, down through slot 2 and up through slot 3.
2.4 Procedure The child must have a bare arm and shoulder for this measurement. The interviewer will have asked the child to wear a sleeveless garment for your visit. Explain to the child and parent the importance of the accuracy of the measurement and that clothing can substantially affect the reading. If the child is wearing a sleeved garment ask her/him to slip their arm out of the garment or to change into a suitable garment. Where possible the left arm should always be used. If the left arm cannot be used, eg because it is in plaster then carry out the measurement on the right arm and record that you have done so in the Nurse Questionnaire at CupMeas. Measuring the length of the informant's upper arm
Measuring the arm circumference
3 Recording ambient air temperature 3.1 The thermometer You have been provided with a digital thermometer and probe. This instrument is very sensitive to minor changes in temperature. It is therefore important that you record temperature at the appropriate time in your routine. It can also take a few minutes to settle down to a final reading if it is experiencing a large change in temperature (eg coming into a warm house from a cold outside). Immediately after you have settled the informant down to rest for five minutes prior to taking their blood pressure set up the thermometer to take a reading. Just prior to recording the blood pressure note the temperature and record it in the appropriate part of the Nurse Questionnaire. Always switch it off after taking a reading, to avoid battery problems. The thermometer automatically switches off if you have left it on for more than 7 minutes. Place the thermometer on a surface near the Dinamap. Do not let the probe touch anything - you can for example let it hang over the edge of a table. Do not put it on top of the Dinamap as it will be warm. 3.2 Instructions for using the thermometer
4 Blood pressure measurement and heart rate readings 4.1 Purpose High blood pressure is an important risk factor for cardiovascular disease. It is important that we look at the blood pressure of everyone in the survey using a standard method so we can see the distribution of blood pressure across the population. This is vital for monitoring change over time, and monitoring progress towards lower blood pressure targets set in the Health of the Nation. 4.2 Eligibility All children aged 5 and over are eligible for this measurement. The technique is exactly the same as with adults. The survey equipment is not suitable for taking the blood pressure of younger children. The only people not eligible for blood pressure measurement are those who are pregnant. However, if a pregnant woman wishes to have her blood pressure measured, you may do so, but do not record the readings in the Nurse Questionnaire. 4.3 Equipment
Extra large cuffs are also available from your Nurse Supervisor, should you require one. The Dinamap 8100 blood pressure monitor is an automated machine. It
is designed to measure systolic blood pressure, diastolic blood pressure,
mean arterial pressure (MAP) and pulse rate automatically at pre-selected
time intervals. On this survey three readings are collected at one minute
intervals.
When the Dinamap is switched on the monitor momentarily displays eights (888s) in all the digital displays and all indicators will flash as a check for the operation of all LEDs. The audio alarm is also sounded as a check for its operation. If on turning on the monitor any of the displays fail to show the 888s, contact the nurse supervisor immediately and inform them that there is a problem with the monitor. 4.4 Preparing the informant The informant should not have eaten, smoked, drunk alcohol or taken vigorous exercise during the 30 minutes preceding the blood pressure measurement. If possible, arrange the timing of the measurements to ensure that this is the case. Ask the informant to remove outer garments (eg jumper, cardigan, jacket) and expose the right upper arm. The sleeve should be rolled or slid up to allow sufficient room to place the cuff. If the sleeve constricts the arm, restricting the circulation of blood, ask the informant if they would mind taking their arm out of the sleeve for the measurement. As with adults, a child's blood pressure reading on a single occasion is not enough to define whether a child's blood pressure is normal or abnormal. In addition the level at which a child's blood pressure is considered to be abnormal will be dependant on that child's age, height and sex. Because of this, unlike the adult situation, you will not be given statements to read out regarding blood pressure for children. Instead we wish you to explain to the parents in advance of the measurement, what the measurement will mean. The Nurse Questionnaire contains a detailed statement at BPBlurb which you should read out to all parents before taking a child's blood pressure. This procedure must always be followed. Otherwise, the parent may feel you are withholding information later because a child has an unsatisfactory result. 4.5 Selecting the correct cuff Adults aged 16+ Do not measure the upper arm circumference. Instead, choose the correct cuff size based on the acceptable range which is marked on the inside of the cuff. You will note that there is some overlap between the cuffs. If the informant falls within this overlap range then use the standard cuff where possible. Children aged 5-15 It is important to select the correct cuff size. The appropriate cuff is the largest cuff which fits between the axilla (underarm) and the antecubital fossa (front of elbow) without obscuring the brachial pulse and so that the index line is within the range marked on the inside of the cuff You will be provided with a child's cuff as well as the other adult cuffs. Many children will not need the children's cuff and instead will require a small adult cuff or a standard adult cuff. You should choose the cuff that is appropriate to the circumference of the arm. Adults and children The appropriate cuff should be connected via the blue pneumatic hose to the two cuff connectors at the bottom of the display. It is important to ensure these screw connectors are properly connected to avoid any air leak. However do not overtighten. The pneumatic seal is not made by tightening the connector. 4.6 The procedure Wrap the correct sized cuff round the upper right arm and check that the index line falls within the range lines. Use the left arm only if it is impossible to use the right. If the left arm is used, record this in the Nurse Questionnaire. Locate the brachial pulse just medial to the biceps tendon and position the arrow on the cuff over the brachial artery. The lower edge should be about 2 cm above the cubital fossa (elbow crease). Do not put the cuff on too tightly as bruising may occur on inflation. Ideally, it should be possible to insert two fingers between cuff and arm. However the cuff should not be applied too loosely, as this will result in an inaccurate measurement. The informant should be sitting in a comfortable chair with a suitable support so that the right arm will be resting at a level to bring the antecubital fossa (elbow) to approximately heart level. If a child is being measured beside a low table it may be necessary to use cushions or a pillow under the arm. They should be seated in a comfortable position with cuff applied, legs uncrossed and feet flat on the floor. Explain to the informant that before the blood pressure measurement we need them to sit quietly for five minutes to rest. They should not smoke, eat, drink or read during this time. Explain that during the measurement the cuff will inflate three times and they will feel some pressure on their arm during the procedure. It is important that children as well as adults rest for five minutes before the measurement is taken. However, making children sit still for five minutes can be unrealistic. It is allowable for them to move around a little. They should not be running or taking vigorous exercise. As with adults, they should not eat or drink during this time. After five minutes explain you are starting the measurement. Ask the informant to relax and not to speak until the measurement is completed as this may affect their reading.
If there are any problems during the blood pressure measurements or the measurement is disturbed for any reason, press the red cancel button or the power OFF button and start the procedure again. If the informant has to get up to do something, then ask them to sit and rest for five minutes again. Do not carry out more than three measurements. Error readings The most common error reading is 844. This is displayed if one measurement exceeds 120 seconds. This is usually caused by the informant moving during the measurement. Ask the informant to sit as still as possible and take the measurement again. Do not palpate the pulse and do not tell the informant that their pulse is erratic. If you still get another 844 error reading, record that it wasn't possible to get a reading and explain to the informant that this sometimes happens. Other error readings are detailed on the side of the Dinamap itself. Do not carry out more than three measurements. 4.7 Informing informants of their blood pressure readings If the informant/parent wishes, record details of the three readings on their Measurement Record Card. If the informant is an adult, record what advice you have given them. a) Child informants (age 5 to 15) We do not wish you to comment on the child's blood pressure readings to the parents. If they seek comment, reiterate what you have already said about not being able to interpret a single blood pressure measurement without checking to see whether it is normal for the child's age and height. Reassure them that if it is found to be abnormal and if they have given consent for the results to go to the GP, then the GP will get in touch to have the measurement repeated. This rule applies for all readings you obtain. b) Adult informants (aged 16+) In answering queries about an adults blood pressure it is very important to remember that it is not the purpose of the survey to provide informants with medical advice, nor are you in a position to do so as you do not have the informant's full medical history. But you will need to say something. What you say in each situation has been agreed with the Department of Health. It is very important that you make all the points relevant to the particular situation and that you do not provide a more detailed interpretation as this could be misleading. Read the instructions below very carefully and make sure you always follow these guidelines. Base your comments on the last two of the three readings. The computer will disregard the first reading when working out which advice to display. If the first reading is higher than the other two, explain that the first reading can be high because people are nervous of having their pressure taken. Definitions of raised blood pressure differ slightly. The Department of Health have decided to adopt the ones given below for this survey. It is important that you adhere to these definitions, so that all informants are treated in an identical manner. These are shown below.
Points to make to the informant about their blood pressure (given on screen) Normal: Mildly raised: 'Blood pressure can vary from day to day and throughout the day so that one high reading does not necessarily mean that you suffer from high blood pressure.' 'You are advised to visit your GP within 3 months to have a further blood pressure reading to see whether this is a once-off finding or not.' Moderately raised: 'Blood pressure can vary from day to day and throughout the day so that one high reading does not necessarily mean that you suffer from high blood pressure.' 'You are advised to visit your GP within 2-3 weeks to have a further blood pressure reading to see whether this is a once-off finding or not.' Considerably raised: 'Blood pressure can vary from day to day and throughout the day so that one high reading does not necessarily mean that you suffer from high blood pressure.' 'You are strongly advised to visit your GP within 5 days to have a further blood pressure reading to see whether this is a once-off finding or not.' Note: If the informant is elderly and has severely raised blood pressure, amend your advice so that they are advised to contact their GP within the next week or so about this reading. This is because in many cases the GP will be well aware of their high blood pressure and we do not want to worry the informant unduly. It is however important that they do contact their GP about the reading within 7 to 10 days. In the meantime, we will have informed the GP of their result (providing the informant has given their permission). 4.8 Action to be taken by the nurse after the visit The action you should take after the visit in respect of raised blood pressure readings, differs for children and adults. If you need to contact the Survey Doctor, do not do this from the informant's home - you will cause unnecessary distress. Pulse - for all informants the survey doctor routinely checks fast and slow pulse rates so no further action is necessary. a) Children No further action is required after taking blood pressure readings on children. All high readings are viewed routinely by the Survey Doctor. However, in the rare event that you encounter a child with a very high blood pressure, ie systolic 160 or above or diastolic 100 or above please call the Survey Doctor. b) Adults The chart below summarises what action you should take as a result of the knowledge you have gained from taking an adult's blood pressure readings. For this purpose you should only take into account the last two readings as the first reading from the Dinamap is prone to error for the reason stated above.
a A hypertensive crisis is an extremely rare complication
of high blood pressure. Its signs and symptoms include b You must still contact the Survey Doctor even if informants tell you that their GP knows about their raised BP. All high or unusual readings will be looked at by the Survey Doctor when they reach the office. If the reading is high, then the Survey Doctor will contact the informant's GP. If the informant is not registered with a GP, or has refused consent for us to contact their GP, the informant will be contacted directly. 5 Measurement of demi-span 5.1 Purpose When the interviewer visits the informant s/he attempts to measure the informant's height and weight. However, measuring height can be quite difficult if the informant cannot stand straight or is unsteady on their feet. This can occur with some elderly people, and with people who have particular disabilities. Additionally, height decreases with age. This decrease varies from person to person, and may be considerable. Prior to the 1991 Health Survey there had been no attempt to measure the height of informants older than 64 years. However, it is becoming more important to have information about the health of the elderly. Therefore an alternative measure of skeletal size, the demi-span, was developed which can be measured easily and does not cause unnecessary discomfort or distress to the elderly or disabled. The demi-span measurement is the distance between the sternal notch and the finger roots with arm out-stretched laterally. 5.2 Eligibility Only those aged 65 or over are eligible for the demi-span measurement. Informants aged 65 or over who cannot straighten either arm, should not have this measurement taken and this reason should be recorded at SpanInt and NotAttM. 5.3 Equipment A thin retractable demi-span tape calibrated in cm and mm A hook is attached to the tape and this is anchored between the middle and ring fingers at the finger roots. The tape is then extended horizontally to the sternal notch (see illustration below).
5.4 Preparing the informant The measurement is made on the right arm unless this arm cannot be fully stretched. In which case the left arm may be used and this should be recorded in the Nurse Questionnaire at SpnM. Although the measurement requires minimal undressing, certain items that might distort the measurement will need to be removed. These include:
Shirts should be unbuttoned at the neck. If the informant does not wish to remove any item that you think might affect the measurement, you should record this in the Nurse Questionnaire at SpanRel but still take the measurement.
5.5 Procedure
5.6 Using the tape The tape is fairly fragile. It can be easily damaged and will dent or snap, if bent or pressed too firmly against the informant's skin. Also the ring connecting the hook to the tape is a relatively weak point. Avoid putting more strain on this ring than necessary to make the measurements. When extending the tape, hold the tape case rather than the tape itself as this puts less strain on the hook and tape. When holding the tape to the sternal notch, do not press into the sternal notch so much that the tape kinks. 5.7 Points to watch Make sure that the informant does not flex their wrist or move their trunk or shoulder when stretching their arm. Be careful that the corner of the hook acting as the zero point does not move away from the finger root so affecting the point from which the measurement is taken. 5.8 Seated and lying measurements If the informant is unable to stand in the correct position, or finds it difficult to stand steadily, ask them to sit for the measurement. Use an upright chair and position it close to a wall. Still try to support the arm if possible. You may need to sit or kneel to take the reading. If the informant is much taller than you, take the measurement with the informant sitting. If the informant finds both standing and sitting in the correct position difficult, the measurement can be taken lying down. If the informant's arm is much longer than yours, support the arm close to the elbow rather than wrist level. Your arm must not be between the elbow and shoulder as this will not provide sufficient support. 6 Measurement of waist and hip circumferences 6.1 Purpose There has been increasing interest in the distribution of body fat as an important indicator of increased risk of cardiovascular disease. The waist-to-hip ratio is a measure of distribution of body fat (both subcutaneous and intra-abdominal). Analyses suggest that this ratio is a predictor of health risk like the body mass index (weight relative to height). 6.2 Eligibility The informant is ineligible for the waist and hip measurement if:
If any of the above apply, record this in the Nurse Questionnaire at WHPNABM. If there are any other reasons why the measurement was not taken, record this at OthWH. 6.3 Equipment Insertion tape calibrated in mm, with a metal buckle at one end. The tape is passed around the circumference and the end of the tape is inserted through the metal buckle at the other end of the tape. 6.4 Preparing the informant The interviewer will have asked the informant to wear light clothing for your visit. Explain to the informant the importance of this measurement and that clothing can substantially affect the reading. If possible, without embarrassing you or the informant, ensure that the following items of clothing are removed:
If the informant is wearing a belt, ask them if it would be possible to remove it or loosen it for the measurement. Pockets should be emptied. If the informant is not willing to remove bulky outer garments or tight garments and you are of the opinion that this will significantly affect the measurement, record this in the Nurse Questionnaire at WJRel and/or HJRel. If possible, ask the informant to empty their bladder before taking the measurement. 6.5 Using the insertion tape All measurements should be taken to the nearest millimetre. If the length lies half-way between two millimetres, then round to the nearest even millimetre. For example, if the measurement is halfway between 68.3 and 68.4, round up to 68.4. And if the measurement is halfway between 68.8 and 68.9, round down to 68.8. Ensure the informant is standing erect in a relaxed manner and breathing normally. Weight should be evenly balanced on both feet and the feet should be about 25-30cm (1 foot) apart. The arms should be hanging loosely at their sides. If possible, kneel or sit on a chair to the side of the informant. Pass the tape around the body of the informant and insert the plain end of the tape through the metal ring at the other end of the tape. To check the tape is horizontal you have to position the tape on the right flank and peer round the participant's back from his/her left flank to check that it is level. This will be easier if you are kneeling or sitting on a chair to the side of the informant. Hold the buckle flat against the body and flatten the end of the tape to read the measurement from the outer edge of the buckle. Do not pull the tape towards you, as this will lift away from the informant's body, affecting the measurement. 6.6 Measuring waist circumference
6.7 Measuring hip circumference
6.8 General points The tape should be tight enough so that it doesn't slip but not tight enough to indent clothing. If clothing is baggy, it should be folded before the measure is taken. If the informant is large, ask him/her to pass the tape around rather than having to 'hug' them. Remember though to check that the tape is correctly placed for the measurement being taken and that the tape is horizontal all the way around. If the measurement falls between two millimetres, the measurement should be recorded to the nearest even millimetre. If your second waist or hip measurement differs by 3 cm or more from the first, then take another measurement to work out which is more correct. If an incorrect measurement has been entered in the Questionnaire, go back and amend it. 6.9 Measuring the waist circumference If you have problems palpating the rib, ask the informant to breathe in very deeply. Locate the rib and as the informant breathes out, follow the rib as it moves down with your finger. If your informant has a bow at the back of her skirt, this should be untied as it may add a substantial amount to the waist circumference. Female informants wearing jeans may present a problem if the waistband of the jeans is on the waist at the back but dips down at the front. It is essential that the waist measurement is taken midway between the iliac crest and the lower rib and that the tape is horizontal. Therefore in this circumstance the waist measurement would be taken on the waist band at the back and off the waist band at the front. Only if the waistband is over the waist all the way around can the measurement be taken on the waistband. If there are belt loops, the tape should be threaded through these so they don't add to the measurement. 6.10 Recording problems We only want to record problems that will affect the measurement by more than would be expected when measuring over light clothing. As a rough guide only record a problem if you feel it affected the measurements by more than 0.5 cm. We particularly want to know if waist and hip are affected differently. 7 Measurement of lung function 7.1 Purpose Lung function tests objectively assess respiratory impairment if it is present. We will be measuring forced expiratory volume in one second (FEV1), forced vital capacity (FVC) and peak expiratory flow (PEF). These measures can be reduced for a wide range of reasons, eg physical unfitness, smoking, chronic bronchitis, those who have had poorly controlled asthma for many years, some muscular disorders and many others. At a population level, these measures tell us a lot about the respiratory health of the population, and are also indicators of general health. As with blood pressure in children, the definition of an acceptable level of lung function depends on the person's age, sex and height. A diagnosis of abnormality is not based on measurement on a single occasion but is rather based on several measurements and on the person's clinical history. Prior to making the measurement, we wish you to explain this to the informants. CAPI will prompt you to read a statement you should always read out before carrying out this test. 7.2 Eligibility Informants aged 7 and to 15, including those chairbound, EXCEPT:
7.3 Equipment The Vitalograph Escort spirometer and case 7.4 Procedure Before using the spirometer it must be calibrated. This procedure can be done in your own home at the start of each day when you are working. If you have more than one visit in the same day you need to calibrate the spirometer only once. The room you calibrate the spirometer in should be of normal room temperature. You will not need to carry the calibration syringe when you make a visit. When you take the measurement in the informant's house the room temperature must be recorded using the thermometer and entered into the spirometer prior to measuring each informant. It is also important that your equipment is at room temperature when you use it. For this reason, take it out of its container as soon as possible when you enter the house. Otherwise it will be too cold (or in summer too hot!) from being in the boot of your car. Calibrating the spirometer - before making any visits
Performing the test - in the informant's home
Instructing the informant to blow
Technically unsatisfactory blows The reason we ask you to assess whether a blow is technically satisfactory is so that if someone has a poor result we can be confident that this really means they have a poor lung function and it is not simply that they have been unable to use the equipment or get the right blowing technique. Do not declare a blow unsatisfactory based on result alone. Pay close attention whilst the informant is carrying out the test and do not be afraid to demonstrate a second or third time if necessary. A technically unsatisfactory blow is any of the following:
Guidelines on expected values of lung function Please note that for any individual their expected level of lung function
is calculated using their height, age and sex. The values given here
are for your guidance only and are based on the best expected
levels in persons of average height. There is in fact wide variation
in the normal level acceptable so these values are just a rough guide.
They will give you an idea of whether an informant is not blowing adequately
so that you can encourage them to improve. You should not say
to informants that their lung function is poor since the variation in
acceptable values is so wide.
7.5 Cleaning procedure for the Escort spirometer For the informant's safety, the mouthpieces you use are valved so that it is not possible to inhale through them. Please always ensure that you use a new disposable mouthpiece for each informant. The mouthpiece may be given to the informant to dispose of in their own household rubbish. It is not necessary to clean equipment between households. It is essential, however, that the filters are removed and cleaned each evening (see diagram below).
The structure of the spirometer 7.6 Important points to note
7.7 Fault finding guide
8.1 Eligibility All persons aged 11 and over, with the following exceptions, are eligible to give blood.
8.2 Purpose Different analytes will be carried out for children and adults. For: Children age 11-15 years inclusive the blood will be analysed for total cholesterol, HDL cholesterol, haemoglobin, IgE, house dust mite specific IgE and ferritin. Adults age 16 years and over the blood will be analysed for total cholesterol, HDL cholesterol, haemoglobin, glycoslated haemoglobin, ferritin, fibrinogen and C-reactive protein. Haemoglobin and ferritin are being measured because they are indicators of nutritional status, being reduced if there is an inadequate iron supply in the diet. Frequently, an inadequate iron supply can imply a more general nutritional problem. Total cholesterol and fibrinogen are being measured because raised levels are associated with higher risks of heart attacks, while HDL cholesterol has a protective role. The level of C-reactive protein in the blood gives information on inflammatory activity in the body, and it is also associated with risk of heart disease. IgE (Immunoglobulin) is produced by the immune system. It is a useful indicator of the risk of allergy and can be raised in some people who have allergic disorders. Not all people with allergic disorders will have raised IgE however and conversley, not all people with raised IgE have an allergic disorder. House dust mite specific IgE is raised where there is an allergy to house dust mites. It is important to appreciate that a diagnosis of allergy in an individual would never be based on a raised IgE alone, but would be based on the clinical history and symptoms of the person in conjunction with the results of such a blood test. Glycated haemoglobin is a measure of the informant's glycaemic status. High levels are indicative of diabetes. The blood will not be tested for any viruses, such as HIV (AIDS).
8.4 The blood tubes For adults aged 16 and over: Three tubes need to be filled. They should be filled in the following order so that, if a situation arises where there will be insufficient blood to fill all the tubes, the analyses with the highest priority can still be undertaken. 1. Plain (red, large) tube. Only use tubes with white
inset in lid. For children aged 11-15 years: Two tubes need to be filled. They should be filled in the following order so that, if a situation arises where there will be insufficient blood to fill all the tubes, the analyses with the highest priority can still be undertaken. 1. Plain (red, large) tube. Only use tubes with white
inset in lid. 8.5 Obtaining consent Before taking blood from 11 to 17 year olds, you must make sure that you always obtain both the informant's own signature and the signature of their parent or person who has legal parental responsibility. Remember that even if 16/17 year old informants are married and not living with their parent or person who has legal parental responsibility, you cannot take blood until you have their parent's consent. It is not sufficient to simply have one signature at items I-III on the BS page of the Consent Booklet. You must make sure that you have all relevant signatures. 8.6 EMLA cream All informants aged 11 to 17 who consent to give a blood sample must be offered EMLA cream. EMLA cream may also be used with older informants who request it, but should not specifically be offered to older informants. Informants who have had a reaction to any anaesthetic (local or general) are not eligible to have EMLA cream. This means that you may not take a blood sample from these informants, unless they consent to give a sample without using EMLA. 8.7 Procedure for taking blood sample
Informants who have a clotting or bleeding disorder, or are currently on anticoagulant therapy, or who have ever had a fit, are NOT ELIGIBLE to give a blood sample. Check if the informant has a clotting or bleeding disorder. These are very uncommon. If you find someone with these problems, do not attempt to take blood, even if the disorder is controlled. By clotting or bleeding disorders we mean conditions such as haemophilia and low platelets, ie. thrombocytopenia. There are many different types of bleeding/clotting disorders but they are all quite rare. The reason these informants are excluded from blood sampling is that:
For the purposes of blood sampling, those who have had, for example, a past history of thrombophlebitis, a deep venous thrombosis, a stroke caused by a clot, a myocardial infarction, an embolus are NOT considered to have clotting disorders. Some informants might be taking anticoagulant drugs such as Warfarin which thins their blood so that they do not stop bleeding easily. If this is the case, then do not take a blood sample. You will need to check this out, particularly with elderly informants. Aspirin therapy is not a contraindication to blood sampling. Informants who have ever had a fit (eg epileptic fit, convulsion) should not be asked to provide a blood sample. This applies even if the fit(s) occurred some years ago. If you are uncertain whether a condition constitutes a contraindication to blood sampling, the Survey Doctor will be happy to answer your queries. 4. Explain the purpose and procedures for taking blood. In addition if the informant is aged 11 to 17
5. Ask if informant is willing to give blood sample 6. If yes and informant is aged 11-17 7. If informant is aged 11-17 and wishes EMLA cream
to be used 8. If informant wishes EMLA cream to be used
If blood sample will be taken NOW, follow 9. onwards. If you will be returning on a separate occasion, complete remainder of interview and arrange separate appointment to return to take blood sample. 9. When you are set to commence blood-taking procedure: Obtain necessary written consents to give blood sample, notify GP of results, and storage of blood sample. Consent sheet BS(A) is for adults aged 18+ and BS(C) is for informants aged 11-17 years. If informant is aged 11-17 you must make sure that you always obtain both the informant's own signature and the signature of their parent or the person who has parental responsibility. Remember that even if 16/17 year old informants are married and not living with their parent or person who has legal responsibility, you cannot take blood until you have their parent's consent. It is not sufficient to simply have one signature at items I-III on the BS (C) page of the Consent Booklet. You must make sure that you have all relevant signatures. There are tick boxes on the consent sheet BS(C) to indicate whether the informant/parent consented to give a blood sample with or without the use of EMLA cream. Please tick the appropriate box. 10. If EMLA Cream is to be used: 11. Take blood sample following the instructions in Section 8.11. 8.8 General information about EMLA Cream EMLA cream is an effective local anaesthetic cream with minimal side-effects. Occasionally mild local skin reactions are experienced. You will need to explain the pros and cons of using EMLA to each informant and parent, in addition to giving them the written note to read. It is important that informants understand that you are not a doctor and cannot treat unexpected reactions. Pros:
Cons:
EMLA contains two anaesthetics: lignocaine and prilocaine. It is important that you ask the question below (also within CAPI) to determine whether the informant has any known anaesthetic allergies. Has the person giving this blood sample ever had a bad reaction to a local or general anaesthetic bought over the counter at a chemist, or given by a doctor, dentist or in hospital? If the informant has ever had a bad reaction to an anaesthetic then EMLA cream MUST NOT be used. However the informant can still give a blood sample without EMLA if they are willing. EMLA is a prescription medication, so it is very important that you account for all EMLA tubes used on the record sheet supplied. Any EMLA tubes you have left at the end of your assignment should be returned to the Brentwood office with the record sheet. For safety, EMLA must not be left lying around where young children could get at it. EMLA cream must only be applied to healthy skin; therefore it must not be applied to sore or broken skin (eg eczema or cuts). Make sure the EMLA cream is kept away from eyes or ears. If the young person requires EMLA to be applied prior to venepuncture, inspect the antecubital fossae and decide which arm you will use for blood-taking. If both arms are suitable, use the left arm. EMLA cream must be applied to ONE arm only. This means that, if you encounter problems during blood-taking (eg collapsing vein), NO ATTEMPT can be made to take blood from the other arm. Apply EMLA cream over the antecubital fossa. Cover with a Tegaderm
dressing (a vapour permeable and self-sticking film dressing) to keep
the EMLA in place. See details about how to apply EMLA below. Please
note the illustration shows EMLA being used on the hand. National
Centre policy is to only take blood samples from the arm.
As you may well be aware, removing the Tegaderm is sometimes painful so take care on hairy arms! It is very important that the used tubes of EMLA should not be left lying around. Make sure you have removed them from the household on completion of the phlebotomy. Use the EMLA record sheet to record the informant's serial number and the date EMLA cream was used. Return this sheet with any unused tubes of EMLA cream to the Brentwood office. 8.10 Preparing the informant Ask the informant if they have had any problems having blood taken before.
Venepuncture is performed with a green twenty one gauge vacutainer needle or butterfly. For children you have the option of using a black 22 gauge Vacutainer needle if it is more appropriate. Grasp the informant's arm firmly at the elbow to control the natural tendency for the informant to pull the arm away when the skin is punctured. Place your thumb an inch or two below the vein and pull gently to make the skin a little taut. This will anchor the vein and make it more visible. Ensure the needle is bevelled upwards, enter the vein in a smooth continuous motion. Remember to take the tubes in the correct order. The first tube should always be the large plain tube with the red cap followed by the EDTA tube and then (if informant aged 16 or older) the blue citrate tube. The vacutainers should be filled to capacity in turn and inverted gently on removal to ensure complete mixing of blood and preservative. Release the tourniquet (if not already loosened) as the blood starts to be drawn into the tube. Remove the needle and place a dental roll firmly over the venepuncture site. Ask the informant to hold the pad firmly for three minutes to prevent haematoma formation. If venepuncture is unsuccessful on the first attempt, make a second attempt on the other arm. If a second attempt is unsuccessful, DO NOT attempt to try again. Record the number of attempts on the Schedule. Record which arm the sample was drawn from (or both). Remove the needle from the vacutainer holder by inserting it into
the slot at the top of the needle disposal box. Push it towards the
narrow end of the slot until the hub fins are engaged. Twist the holder
anti-clockwise to unthread the needle. Then slide the holder towards
the centre of the slot, allowing the needle to drop into the container.
Check on the venepuncture site and affix an adhesive dressing, if the informant is not allergic to them. If they are allergic, use a dental roll secured with micropore. 8.12 Fainting informants If an informant looks or feels faint during the procedure, it should be discontinued. The informant should be asked to place their head between their knees. They should subsequently be asked to lie down. If they are happy for the test to be continued after a suitable length of time, it should be done so with the informant supine and the circumstances should be recorded. They may wish to discontinue the procedure at this point, but willing to give the blood sample at a later time. 8.13 Disposal of needles and other materials Place the used cotton wool balls in the sharps box and put gloves etc in the self-seal disposal bag. The needle disposable box should be taken to your local hospital for incineration. Telephone them beforehand, if you are not sure where to go. If you come across any problems with the disposal, contact the Survey Doctor who will contact your local hospital. The sealed bag can be disposed of with household waste as long as it does not have any items in it that are contaminated by blood. 8.14 Needle stick injuries Any nurse who sustains such an injury should seek immediate advice from their GP. The nurse should inform his/her nurse supervisor of the incident, and the nurse supervisor should inform Vasant Hirani or Marian Brooks at UCL 8.15 Informants who are HIV or Hepatitis B positive If an informant volunteers that they are HIV or Hepatitis B positive, do not take a blood sample. Record this as the reason on the Schedule. You should never, of course, seek this information. 9 Fasting blood sample 9.1 Eligibility All persons aged 35 and over, with the following exceptions, are eligible to give blood.
For a fuller description about clotting or bleeding disorders see Section 8.7 above. 9.2 Purpose The analytes on the fasting blood sample are LDL cholesterol, triglycerides and glucose. LDL cholesterol and triglycerides, together with total and HDL cholesterol, provide a lipid profile which can give information on the risk of cardiovascular disease. The glucose is being measured on the fasting blood sample as an indicator of diabetes, which is characterised by chronic hyperglycemia. 9.3 Equipment Blood sample equipment as in Section 8.3 plus Vacutainer plain red tubes and Vacutainer grey fluoride tubes. Two tubes should be filled for eligible adults. They should be filled in the following order so that if a situation arises where there will insufficient blood to fill all the tubes, the analyses with the highest priority can still be undertaken.
If the fasting blood sample is to be taken at the same time as a non fasting sample, then priority should be given to filling the non fasting blood tubes. 9.4 Procedure for taking the sample
10 Saliva sample collection We wish to obtain a measure of exposure to passive smoking. This can be detected by measuring the level of cotinine in saliva. Cotinine is a derivative of nicotine and shows recent exposure to tobacco smoke, either because the individual is a smoker or because they have been exposed to other people's tobacco smoke. Cotinine can also be detected in serum, and this method was used in 1997 for those aged 16-24 while collecting salivary cotinine for children. For 1999, it has been decided to obtain a saliva sample from adults as well as children. Note that informants' cotinine analysis results will not be sent to them or their GP. 10.1 Eligibility A saliva sample should be obtained from all informants aged 4 and over. 10.2 Equipment For adults (aged 16+): For children (aged 4-15): The straw makes it easier for children to direct their saliva sample into the tube. Its use will also minimise the amount of other items that are included in saliva, such as crumbs, which might enter the tube. 10.3 Procedure The aim is to get as much saliva as possible into the tube. For adults: The procedure is very simple, but it is crucial to make sure that an adequate amount of saliva is collected.
For children:
10.4 Packaging the saliva sample
Continue to pack as instructed from point 6 onwards in Section 11.2 'Packing the blood samples'. 11 Sending blood and saliva samples to the laboratory The blood samples are sent to the Royal Victoria Infirmary Laboratory in Newcastle-upon-Tyne. It is important that the blood is sent properly labelled and safely packaged and that it is despatched immediately after it has been taken. 11.1 Labelling the blood tubes Label the tubes as you take the blood. It is vital that you do not confuse blood tubes within a household. Use the set of serial number and date of birth labels (red) to label the vacutainer tubes. Attach a serial number label to every tube that you send to the lab. Enter the serial number and date of birth very clearly on each label. Make sure you use blue biro - it will not run if it gets damp. Check the Date of Birth with the informant again verbally. Stick red label over the label already on the tube. The laboratory need to be able to see on receipt how much blood there is in the tube. We cannot stress too much the importance of ensuring that you label each tube with the correct serial number for the person from whom the blood was obtained. Apart from the risk of matching up the blood analyses | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
