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Less is better: why venepuncture practice should be reviewed for those with end-stage renal failure

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Carol Hewart, RN, Dip HE (adult) Nursing.

Renal Nurse, Renal Unit, Derriford Hospital, Plymouth, Devon

The kidney has a fundamental role in maintaining a person's haemoglobin level. Before the manufacture and introduction of the synthetic version of the hormone erythropoietin (EPO), anaemia was a major problem for end-stage renal failure (ESRF) patients, and therefore for the renal multidisciplinary teams caring for them.

The kidney has a fundamental role in maintaining a person's haemoglobin level. Before the manufacture and introduction of the synthetic version of the hormone erythropoietin (EPO), anaemia was a major problem for end-stage renal failure (ESRF) patients, and therefore for the renal multidisciplinary teams caring for them.

Now that an established medication exists to rectify this problem for most ESRF patients, it opens the door for nurses to question the factors that contribute to a patient's anaemia. One area of focus has been the importance of conserving as high a level of haemoglobin in the blood as possible.

This paper examines current practices that could have a detrimental effect on the patient's haemoglobin level and, in particular, the impact of repeated venepuncture. It proposes that replacing adult vacutainers with paediatric ones during venepuncture could save a considerable amount of haemoglobin over a year's monitoring of a patient's biochemistry.

The function of the kidney
The kidney has two primary functions in maintaining a person's life: the removal of waste products from the body's normal metabolic processes and/or toxins, and the maintenance of homeostasis (Challinor and Sedgewick, 1998).

However, the kidney is also a hormonal organ, and therefore has a number of endocrine functions. One of these is the production of erythropoietin. This is a hormone that activates the production of red blood cells in the bone marrow (Gutch et al, 1999). The absence or significant reduction of the erythropoietin hormone circulating in the blood can lead to anaemia in the ESRF patient (Paganini, 1994; Wharton, 1997). Gutch et al (1999) stated that the normal haematocrit level for a man is 46-52% and for a woman 40-45%. This equates to 12 to 16g/dl of haemoglobin contained within the blood (Stanton, 1999). In the past, it was possible to find ESRF patients with significant anaemia with levels of less than 8g/dl (Wharton, 1997).

The effect of anaemia on the ESRF patient
The chronic nature of renal failure means there is a gradual reduction in function. Because of this, an ESRF patient may not be fully aware of the extent of their anaemia and how much impact it is having on their life. Hendrix (1996) found that significant anaemia could affect patients' ability to function both physiologically and psychologically. Cohen and Brattich (1997) found that an anaemic renal patient might well use up to 50% of their available oxygen just to walk.

Anaemia can also have an important effect on the patient's cognitive abilities. Martin-Lester (1997) suggested that a renal patient with low haemoglobin might have significant difficulty in processing information. This could lead to problems with the nurses' role of educating the patient about renal failure. The aim of renal care, in the author's unit, is partnership between the patient and nurse, and therefore poor cognition can have a direct effect on this process.

The same haemoglobin level can have different effects in different individuals (Macdougall, 2001). This is important, as anaemia can lead to the renal patient developing co-morbidity such as cardiac failure (Owen, 1997).

The correction of anaemia has been seen as an achievable target by the UK Renal Association and European Standards. The target level is a minimum of 10g/dl for ESRF and 11g/dl in chronic renal failure (Nephrology Dialysis Transplantation, 1999) and is reflected in the aims of many units, with established improvements in the patient's quality of life (Burrows-Hudson 1997; Cohen and Brattich, 1997).

Breiterman-White (1996) pointed out that nephrology teams are focusing on improving issues for renal patients within existing budgets. This has been the case in the author's unit, where an experienced renal nurse has been appointed, whose role is to manage and offset the cost by more effective use of expensive medication tailored to meet patients' needs.

A number of authors have explored the issue of low haemoglobin (Marooney, 1998; Breiterman-White, 1999). The involvement of multidisciplinary teams has also been explored (Sanders et al, 1999).

Most literature suggests that anaemia could have a significant impact on the morbidity and mortality of ERSF patients and thus their quality of life (Mathers, 1995). The research examines various ways of maintaining or improving patients' low haemoglobin through appropriate medication. Many methods have been identified, ranging from hormone replacement therapy, using synthetic erythropoietin, and/or blood transfusions, to actions as simple as minimising blood loss during the dialysis process.

Breiterman-White (1999) suggests the process of haemodialysis itself could be part of the cause of insufficient haemoglobin levels, through clotting on the kidney and damage to haemoglobin because of trauma. Studies have shown that peritoneal dialysis resulted in less blood loss than haemodialysis, due to the consistent chronic loss of blood from haemodialysis (Nissenson and Strobos, 1999).

Although most units have policies and procedures such as ensuring wash back of corporeal circuit blood, significant loss can still occur at each dialysis. The author has observed that the process of connecting or disconnecting the patient to the dialysis machine has led to a loss of approximate 10ml of blood by each patient on each dialysis. This is due to the necessary removal of the heparin lock from 'permanent' lines, along with the unavoidable loss of haemoglobin in the dialysis lines or in the temporary cannulae used to access fistulae or grafts, following the process of washing the blood back to the patient at the conclusion of dialysis.

The loss of haemoglobin is an inevitable consequence of haemodialysis, but multidisciplinary team members need to be inventive in how they care for patients and manage their haemoglobin levels. There is always room for improvement and professionals should not become complacent.

The use of EPO
The use of effective medication has reduced the need for blood transfusions and their associated risks (Cohen and Brattich, 1997). EPO has improved the outcome and care of ESRF patients with anaemia (Macdougall, 1999).

However, Davis et al (1998) argued that a simple injection does not always correct low haemoglobin. Hendrix (1996) suggested this was because 'most patients receiving EPO will eventually require iron supplements'. For EPO to work successfully sufficient iron stores have to be available (Johnson et al, 1999; Macdougall, 1999). Hattersley and Bell (1997) explain that: 'Ferritin is the main stored iron form found in all tissues.'

Therefore due to this intervention, the renal team has to successfully monitor ferritin levels (Fishbane et al, 1997; Johnson et al, 1999). This is to ensure adequate levels without the risk of overload. Macdougall's research (1999) showed that overload in this area has been greatly reduced due to the reduction in blood transfusions and the extensive use of EPO as a replacement. Robbins (2000) supported Macdougall's (1999) stance that iron overload, more prevalent before the introduction of EPO as blood transfusion, was the only realistic way to maintain anaemic patients' haemoglobin.

Curtin et al (1999), however, identified a problem of patients not complying with taking oral iron, due to the side-effects. Thus, intravenous iron has been increasingly used in place of oral medication. Macdougall (1999) suggests the reason for this change is the poor absorption and side-effects of iron via the oral route.

Fishbane et al (1997) propose that when EPO therapy begins, ferritin blood levels should be monitored monthly, and weekly haemoglobin levels taken. It is not clear if this would be as well as current routine blood sampling - the authors also say that continuing monitoring is required. They do not propose the range or type of equipment required for this monitoring. Nor do they say that introducing EPO would lead to an increase in phlebotomy. This suggests the volume of blood taken before the start of EPO therapy might have been higher than necessary.

The impact of venepuncture
Frequent phlebotomy is needed within the renal specialty; but this action may have a significant effect on the haemodialysis patient's haemoglobin.

The frequency and volume of venepuncture taken within each dialysis unit is open to question, in the opinion of this paper's author. This view is supported by Andrews et al (1999), who state that those working within the intensive care area (ICU) should question their current practice in relation to phlebotomy and encourage use of more 'micro-testing' to reduce loss of haemoglobin.

Although they do not suggest inappropriate blood sampling has been carried out, they point to areas of improvement. They conclude that present-day procedures could contribute to patients developing anaemia.

Hashimoto (1982) found a similar situation, and concluded that the depletion of iron equalled to 10 times a man's normal daily deficit and therefore may lead to the patient requiring oral or intravenous medication. Elstrom (1989) found that it was policy for three times more blood to be taken than that needed for diagnostic purposes.

Clearly if these figures are reflected on a month-by-month basis, significant blood loss could be reduced. It seems incredible that on the one hand patients are subject to yet more medication while on the other hand the renal team are extracting large amounts of blood for diagnostic purposes. Andrews et al (1999) suggest that greater use of 'micro-testing' should be encouraged.

A proposed change in practice
It is current practice in the author's unit to use adult volume vacutainers for haemostatic monitoring. But why use adult containers when they could be replaced with paediatric vacutainers, leading to a significant reduction in the volume of blood required for diagnostic purposes? The paediatric containers require about a quarter of the volume of blood of adult containers. This could equate to an estimated yearly saving of blood volume of 216ml per patient (Table 1). Another way of looking at this volume would be that it equates to a significant part of a unit of blood. This is the minimum saving, as intermittent monitoring can occur over and above monthly monitoring.

However, as with most things, there is a cost involved. Within the author's unit, paediatric vacutainers are slightly more expensive. Any increase in costs could be offset by reductions in other areas and that may have an increased benefit for the patient, nurse and unit. Ultimately it could lead to a possible reduction in the EPO dose required or the need for intravenous iron due to the reduction in the blood sample volume.

Due to time constraints the author could not establish if other specialties would benefit from a change in use from adult to paediatric vacutainers. But if renal patients are at risk from venepuncture anaemia, then other patients could be as well.

Conclusion
Haemodialysis leads to loss of haemoglobin, even when the dialysis nurse adopts accepted best practice. Research suggests that, as within other disciplines, there is excessive blood loss in venepuncture and that this aspect of patient care has not changed for quite a long time.

Haemodialysis requires frequent and accurate biochemistry and microbiology analysis by the nephrology team. The team has developed a policy of monthly blood examination providing monthly results. This is a legitimate action and many working within the renal area may see it as a necessary evil. However, as discussed here, the volume of blood required for these routine results can cause further problems to the patient over time.

Every professional should adopt a questioning approach to the care of their patients There is room for improvement in the area of phlebotomy, and a complacent attitude towards blood loss may have emerged since the introduction of EPO. The development of 'micro testing' and use of paediatric vacutainers would allow dialysis care to be maintained without excessively compromising patients' haemoglobin.

The argument for further use of minimal techniques should be encouraged within this field. Even if research does not conclude that there has been a financial benefit to the unit, the renal patient is likely to benefit. The best approach for all patients, including those in renal units, in relation to venepuncture, should be 'minimum is best'.

Following the findings of this critical research, the author gave a presentation to her unit's multidisciplinary team with the aim of encouraging the use of paediatric vacutainers. There was a positive response from all who attended and it was agreed to have a preference for paediatric samples for inpatients. However, the findings are currently anecdotal and a multi-centred randomised controlled study needs to be carried out to confirm the inferred benefits.

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