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mobility or the capacity of staff to provide care in the event of an adverse reaction. The estimation of blood volume is more difficult in obese individuals as fat contains proportionately less blood than muscle. Hence, blood volume may be overestimated (69), resulting in an increased risk of an adverse reaction. 42 For apheresis procedures, the total volume of donated plasma, platelets and red cells collected should not exceed 13% of total blood volume (70) and the maximum extracorporeal blood volume should not exceed 15% of the donor’s total blood volume at any stage of the procedure. In practice, this requires that plateletpheresis and plasmapheresis donors should weigh at least 50 kg. Prospective donors of double red cell apheresis donations should have an estimated blood volume of more than 5 litres; this requirement is generally met by non-obese individuals weighing more than 70 kg. The reasons for any obvious rapid weight loss should be ascertained. Recommendations n In determining a lower weight limit for blood donors, the BTS should consider norms for the weight of the population; if a significant proportion of the donor population weighs less than 45 kg or 50 kg, collection volumes may be reduced accordingly, while ensuring that blood collection bags and their anticoagulant content are adjusted to be compatible with the volumes collected n Prospective donors of whole blood donations should weigh at least 45 kg to donate 350 ml ± 10% and 50 kg to donate 450 ml ± 10% n Prospective donors of apheresis platelet or plasma donations should weigh at least 50 kg n Prospective donors of double red cell apheresis donations should have an estimated blood volume of more than 5 litres; this requirement is generally met by non-obese individuals weighing more than 70 kg. 4.5 VITAL SIGNS 4.5.1 Pulse A normal pulse rate of 60–100 per minute and a regular rhythm are indicators of good health; many BTS recommend that these are examined prior to donation. The ability to detect significant abnormalities of pulse rate or rhythm depends on the skill and experience of staff. The usefulness of this examination in a blood donation setting needs to be assessed. 4.5.2 Body temperature A prospective donor who is febrile – defined as a core oral temperature more than 37.6°C (71) – is by definition unwell and should be deferred. Fever can indicate any number of medical conditions and infections, but is usually associated with other symptoms (also refer to Section 4.3 on minor illnesses). 4.5.3 Blood pressure (BP) A normal blood pressure (systolic 120–129 mmHg, diastolic 80–89 mmHg) is generally regarded as an indicator of good health (72). The measurement of BP is required by many national guidelines on donor selection and some BTS set an upper limit of BP for blood donors (70) on the basis that uncontrolled hypertension is an independent risk factor for cardiovascular disease. However, a systematic review of the literature found no evidence that raised baseline blood pressure, treated hypertension or low blood pressure were 43 predictive of increased adverse reactions, although the level of evidence was limited (73). BP may be measured routinely for the purposes of health screening; however, the blood collection session is not the ideal setting for this. Donor anxiety may result in the temporary elevation of systolic BP. Accurate BP measurement requires the availability of calibrated equipment, suitable facilities, adequate time and appropriately skilled staff. Recommendations n In assessing whether pulse, temperature or blood pressure should be measured routinely, selectively or not at all at the time of blood donation, the BTS should consider: — Clinical value of these parameters in the blood donation setting — Availability of adequate equipment (calibrated and sterile, where appropriate), space and time. If blood pressure is used as a selection criterion for blood donation, arbitrary acceptable limits of systolic BP of 100–140 mmHg and arbitrary acceptable limits of diastolic BP of 60–90 mmHg are suggested — Competence and experience of staff and their ability to perform techniques correctly 4.6 DONOR IRON STATUS 4.6.1 Haemoglobin screening There are no rapid, simple and direct bedside methods for determining iron status. The pre-donation assessment of donor haemoglobin remains the best approach. Normal ranges for haemoglobin and red cell indices differ between ethnic populations, and in males and females, and are also affected by age, especially in women (74,75). International and national guidelines (Annex 1) commonly recommend minimum haemoglobin levels of 12.5 g/dl for females and 13.5 g/dl for males but further studies are needed to justify the selection of these levels. In some countries, the same haemoglobin level is used for

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