1 Department of Anaesthesiology and Intensive Care, Münster University Hospital, D-48149 Münster, Germany, E-mail: jahn@anit.uni-muenster.de
The development of the first portable blood glucose monitors introduced an epoch-making new concept into clinical medicine.1 The ability to measure laboratory variables in acute situations near the patient was an appealing way to improve clinical efficiency and patient care. A new trend began, reversing an earlier tendency towards centralization that had begun in hospitals during the 1960s in the course of modernization, rationalization, and the introduction of automation processes.2 This fundamental shift in diagnostic testing was accompanied by significant advances in technology, with miniaturization of analysers and a remarkable increase in the numbers of different diagnostic and analytic tests available.3
Near-patient testing, ancillary testing, bedside testing, alternative-site testing, decentralized testing, out-of-laboratory testing, and most commonly point-of-care testing, are synonymous terms meaning that analytical testing of patient specimens can be performed at or near the location of patient care.4 Near-patient testing does not mean providing a wide variety of laboratory blood tests with small analysers, nor does it mean performing analytic tests in small and decentralized laboratories. It stands for laboratory analysis using an easy-to-operate (point-of-care) device, with rapid availability of the test results, in clinically sensitive areas, carried out by personnel who may or may not have some minimal training and experience in the field of laboratory medicine.5
Particularly in critical areas such as intensive care units, operating and recovery rooms, emergency wards, and delivery rooms, near-patient testing has become increasingly important during the past decade, and it is now an indispensable element of everyday clinical routine. However, with the increasing popularity of near-patient testing, there is a risk that such testing may expand in an uncritical and unjustified way. Anaesthetists, intensive care specialists, and emergency ward physicians want rapid results, creating a growing demand for such tests, and the manufacturing industry is steadily increasing the range of analytic tests available.5 6
It is therefore not surprising that near-patient testing has become controversialin addition to differing opinions among clinicians and laboratory staff, there are many questions concerning the advantages, disadvantages, and economic and health-care aspects of near-patient testing that have yet to be resolved. Several professional bodies have evaluated the pros and cons in near-patient testing in order to develop guidelines for implementing and setting up near-patient testing facilities.79
Clinical and organizational advantages
Analytical results are provided more rapidly and effectively with near-patient testing, with a decreased test turnaround time, which can allow a shorter therapeutic response interval or prompt therapy control. Problems with specimen identification and transportation do not arise with near-patient testing. The analysers require only small amounts of whole-blood samples, utilize ready-to-use reagents, and the operators level of competence is not important, as a trained laboratory technician is not required. The pre-analytic period is shortened and simplified, as there is no need for specialized specimen preparation, such as centrifugation or the addition of extra reagents. This is of special relevance when unstable metabolites are to be measured. An advantage that is certainly minor, although often mentioned, is the substantially improved convenience for the patient and for the staff performing the test. 69 10
Disadvantages and risks of near-patient testing
In particular, laboratory physicians and clinical chemists have criticized the lack of analytical performance and quality control of near-patient testing. There are concerns about the reliability of results obtained by non-laboratory personnel, who are often insufficiently or not at all familiar with the analysers they are using. Essential calibration procedures may not be performed, or may only be carried out rarely and/or inadequately. New tests may be adopted uncritically and in an indiscriminate way. As a result of the different methods used, the comparability of the results is limited. Insufficient documentation of the results and of the operating service are criticisms that affect data processing, data transfer, and the data network, particularly with regard to data connections with the central laboratory. In addition, near-patient testing makes additional time demands on physicians and nurses.68 1012
There are rigorous standards for the quality control of clinical laboratories (mostly based on national standards established by the relevant professional bodies in each country), which have led to improved comparability between analytical results from different laboratories. Comparable standards for whole-blood methods of near-patient testing, limiting the variation in results, have unfortunately not yet been developed in all hospitals.9 1316 In some countries, it is a legal requirement that the quality control of near-patient testing is performed by skilled personnel from the central laboratory. Consultation with the head of the laboratory department in each hospital is therefore mandatory before introduction of near-patient testing into clinical practice.
In this issue of the British Journal of Anaesthesia, Johi, Cross and Hansbro17 present a paper investigating near-patient testing in cardiac surgery. They measured prothrombin time and activated partial thromboplastin time (APTT) in the pre-bypass and post-bypass phase with a near-patient testing device and compared the results with those obtained from a conventional laboratory using established methods. In the post-bypass period, the differences in the results for the measurement of APTT are alarming.
Patient benefit, costbenefit ratio, and economic considerations
Near-patient testing comes with a price tag. The costs of numerous analysers that need to be provided in different critical areas, and the expense of reagents, sample tubes, specimen containers, calibration fluids, and all the materials needed to operate the devices are additional to central laboratory expenses, and they are immense. Implementation of near-patient testing devices for certain laboratory variables often does not entirely replace their measurement in the central laboratory, and therefore does not necessarily reduce central laboratory costs.
Several studies, have been published with controversial results, that attempt to compare the costs of near-patient testing with those of conventional laboratory testing with regard to the costbenefit ratio.1820 The real costs are difficult to determine, as absolute comparisons are extremely difficult to carry out, and there are wide variations in the costs associated with central laboratories and near-patient testing.21 The expenses of training staff, and of obtaining supplies and personnel for near-patient testing in comparison with laboratory testing are only a few of the key aspects involved in assessing costs, and different conditions apply in each hospital. In order to effectively assess the costbenefit ratio of near-patient testing, each hospital therefore has to evaluate it in its own unique circumstances.22
There is universal agreement that near-patient testing can be a prerequisite for early recognition of life-threatening conditions, and for early therapeutic intervention and effective short-term therapy control. If this genuinely results in a significant improvement in patient care, reduced length of stay in an intensive care unit and/or hospital, decreased blood product usage, and reduced morbidity and/or mortality, then the benefits of near-patient testing will far outweigh the costs and will justify its use.18 19 22 23 In a study of patients who underwent coronary revascularization, near-patient testing was beneficial in the early detection of bleeding and anaemia. This clinical benefit was clearly associated with positive economic effects.18
However, in a controlled and randomized investigation of 1728 patients in an emergency department, Kendall and co-workers found that, although near-patient testing resulted in reduced turnaround times and earlier therapeutic interventions, it did not lead either to differences in the length of stay in the emergency department and hospital, or to a reduced mortality rate. The authors concluded that the often-cited advantages of the reduced turnaround time provided by near-patient testing did not significantly affect the relevant variables.24 Similar results were obtained by Parvin and co-workers.25
Another investigation by Kilgore and colleagues, provided evidence that near-patient testing may result in reduced acceptance and satisfaction among employees. Small satellite laboratories were found to be preferable, but employee satisfaction with near-patient testing was still greater than satisfaction with the central laboratory.26
There is no doubt that near-patient testing may in many respects be an advantageous tool in modern medicine. It is essential that clinicians and laboratory staff work closely together and establish arrangements that can bring the accuracy of near-patient devices close to that of laboratory methods, as has been demonstrated for the measurement of blood glucose.6
Conclusion and recommendations for the implementation of near-patient testing
1. At present, near-patient testing is not a replacement for conventional laboratory services, but rather a supplement to it.
2. Uncritical and unjustified expansion of near-patient testing technology provides more data and more costs rather than reliable information and benefit.
3. Near-patient testing may cause economic stresses, depending on many variables.
4. A strong multidisciplinary and interdepartmental team approach is necessary to ensure cost-effectiveness, better analytical performance, reliability, comparability, and quality control.
5. Depending on the local situation, a consensus has to be achieved among clinicians and laboratory physicians. Larger central laboratories should nominate a member of staff to be responsible for near-patient testing, who can supervise the quality control of the results obtained.
6. It has not been unequivocally proven that the putative advantages of near-patient testing result in a reduced length of stay, an increased hospital discharge rate, and reduced morbidity and mortality rates.
7. Near-patient testing should be rigorously restricted to the measurement of vital functions with a requirement for an immediate therapeutic response, for example blood glucose measurement.
8. Other variables that can be measured include haematocrit, haemoglobin, arterial blood gases, sodium, potassium, ionized calcium, lactate, activated whole-blood clotting time, and troponin.
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