Testing at the Point-of-Care: Errors of Omission in the Patient Care Pathway

Critical appraisal in the practice of laboratory medicine

Critical appraisal is a key skill employed across the spectrum of laboratory medicine practice. It underpins the use of information that is relevant, of good quality and is meaningful. Relevance is answering the right question for the right patient at the right time, with quality ensuring provision of the right information. Meaningful is making the right decisions in order to deliver the right outcomes. Critical appraisal is about minimizing the risk of bias or 'departures from trueness' in all of the facets of laboratory medicine practice. It can be summarized in four steps: (i) a clear understanding and articulation of the problem being addressed - whether it be an analytical challenge, individual patient care or policymaking; (ii) verifying the methodological approach employed; (iii) assuring the reliability of the results and (iv) ensuring the applicability and implications of the results. Reference is made to a number of checklists that can be used to assist in the process of critical appraisal.

Measurement of natriuretic peptides at the point of care in the emergency and ambulatory setting: current status and future perspectives

The measurement of natriuretic peptides (NPs), B-type NP or N-terminal pro-B-type NP, can be an important tool in the diagnosis of acute heart failure in patients presenting to an Emergency Department (ED) with acute dyspnea, according to international guidelines. Studies and subsequent meta-analyses are mixed on the absolute value of routine NP assessment of ED patients. However, levels of NPs are likely to be used also to guide treatment and to assess risk of adverse outcomes in other patients at risk of developing heart failure, including those with pulmonary embolism or diabetes, or receiving chemotherapy. Natriuretic peptide levels, like other biomarkers, can now be measured at the point of care (POC). We have reviewed the current status of NP measurement together with the potential contribution of POC measurement of NPs to clinical care delivery in the emergency and other settings. Several POC systems for measuring NP levels are now available: these produce test results within 15 minutes and appear sufficiently sensitive and robust to be used routinely in diagnostic evaluations. Point-of-care systems could be used to assess NP levels in the ED and community outpatient settings to monitor the risk of acute heart failure. Furthermore, the use of protocol-driven POC testing of NP within the time frame of a patient consultation in the ED may facilitate and accelerate the throughput and disposition of at-risk patients. Appropriately designed clinical trials will be needed to confirm these potential benefits. It is also important that processes of care delivery are redesigned to take full advantage of the faster turnaround times provided by POC technology.

Ask the right question: a critical step for practicing evidence-based laboratory medicine

The purpose of laboratory medicine is to facilitate better decision making in clinical practice and healthcare delivery. Decision making implies an unresolved issue, problem or unmet need. The most important criterion for any investigation to be of value in clinical practice is that it addresses an unmet need. The different ways in which laboratory investigations are utilized in patient care can be represented in the form of questions. It is important that these questions are articulated to highlight the variables that will impact on the effectiveness of the investigation in the scenario being considered. These variables include the characteristics of the patient (or population) and clinical setting, the nature of the decision and action taken on receipt of the test result and the expected outcome. Asking a question is the first step of the evidence-based laboratory medicine (EBLM) cycle, the other steps being acquiring the evidence, critically appraising the evidence, applying the evidence and auditing use of the evidence. Getting the question right determines the quality of the whole process, thus, defines the quality in practice of laboratory medicine. Whilst the main focus of the EBLM cycle is to provide a strong evidence base for use in clinical practice, it is clear that the five steps are equally applicable in commissioning, delivery and audit (performance management) of services. Asking the right question is crucial to improving the quality of evidence, and practice, in laboratory medicine, and should be used in routine laboratory medicine practice and management throughout healthcare.

Cardiac troponin: a critical review of the case for point-of-care testing in the ED

The measurement of cardiac troponin concentrations in the blood is a key element in the evaluation of patients with suspected acute coronary syndromes, according to current guidelines, and contributes importantly to the ruling in or ruling out of acute myocardial infarction. The introduction of point-of-care testing for cardiac troponin has the potential to reduce turnaround time for assay results, compared with central laboratory testing, optimizing resource use. Although, in general, many point-of-care cardiac troponin tests are less sensitive than cardiac troponin tests developed for central laboratory-automated analyzers, point-of-care systems have been used successfully within accelerated protocols for the reliable ruling out of acute coronary syndromes, without increasing subsequent readmission rates for this condition. The impact of shortened assay turnaround times with point-of-care technology on length of stay in the emergency department has been limited to date, with most randomized evaluations of this technology having demonstrated little or no reduction in this outcome parameter. Accordingly, the point-of-care approach has not been shown to be cost-effective relative to central laboratory testing. Modeling studies suggest, however, that reengineering overall procedures within the emergency department setting, to take full advantage of reduced therapeutic turnaround time, has the potential to improve the flow of patients through the emergency department, to shorten discharge times, and to reduce cost. To properly evaluate the potential contribution of point-of-care technology in the emergency department, including its cost-effectiveness, future evaluations of point-of-care platforms will need to be embedded completely within a local decision-making structure designed for its use.