Evaluation of point-of-care testing in critically unwell patients: comparison with clinical laboratory analysers and applicability to patients with Ebolavirus infection

Preparing of Point-of-Care Reagents for Risk Assessment in the Elderly at Home by a Home-Visit Nurse and Verification of Their Analytical Accuracy

With the rising number of older adults residing at home, there is a growing need for risk assessment and patient management in home nursing. This study aims to develop point-of-care test (POCT) reagents that can aid in risk assessment and home care, especially in settings with limited resources. Our focus was on creating a C-reactive protein (CRP) POCT, which can accurately diagnose clinically significant judgment values in home nursing. Additionally, we assessed the utility of the HemoCue WBC DIFF system in providing differential counts of white blood cells (WBC). These performances were compared with a laboratory test using blood samples from patients with pneumonia. The CRP POCT showed a comparable result to that of a laboratory method, with an average kappa index of 0.883. The leukocyte count showed good agreement with the reference method. While the correlation coefficients for both neutrophil and lymphocyte counts were deemed acceptable, it was observed that the measured values tended to be smaller in cases where the cell count was higher. This proportional error indicates a weak correlation with the neutrophil-to-lymphocyte ratio. CRP POCT and WBC counts provided reliable and accurate judgments. These tools may benefit risk management for older adults at home, patients with dementia who cannot communicate, and those living in depopulated areas.

Whole-blood Point-of-Care Activated Partial Thromboplastin Time Ratio (APR) is not Accurate Enough to Monitor Heparin Therapy in Patients with Severe Respiratory Failure Secondary to SARS-Cov-2 Infection Supported with Veno-Venous Extracorporeal Membrane Oxygenation (VV-ECMO)

Support with VV-ECMO requires anticoagulation with unfractionated heparin to prevent thrombotic complications. This must be monitored due to bleeding risk. A point-of-care (POC) method of testing aPTT and APR was evaluated for agreement with laboratory methods. In a prospective observational study, patients supported on VV-ECMO as a result of severe respiratory failure secondary to Covid-19 infection were given heparin as part of standard therapy. The aPTT was measured (i) at the bedside using the Hemochron Signature Elite device and (ii) at the hospital laboratory. Duplicate results were compared. Agreement between the POC and laboratory tests was poor, as assessed using the Bland-Altman method. The maximum difference between POC and laboratory methods was 133% and the minimum was 0%. Overall bias was 7.3% and limits of agreement were between -43.8% and 58.5%. Correlation increased when results were normalised to platelet count and creatinine. This POC test is insufficiently accurate for use as the primary method of heparin monitoring in patients requiring VV-ECMO for Covid-19. Platelets and renal function may influence the result of this whole blood POC test.

Clinical Laboratory Biosafety Gaps: Lessons Learned from Past Outbreaks Reveal a Path to a Safer Future

Patient care and public health require timely, reliable laboratory testing. However, clinical laboratory professionals rarely know whether patient specimens contain infectious agents, making ensuring biosafety while performing testing procedures challenging. The importance of biosafety in clinical laboratories was highlighted during the 2014 Ebola outbreak, where concerns about biosafety resulted in delayed diagnoses and contributed to patient deaths. This review is a collaboration between subject matter experts from large and small laboratories and the federal government to evaluate the capability of clinical laboratories to manage biosafety risks and safely test patient specimens. We discuss the complexity of clinical laboratories, including anatomic pathology, and describe how applying current biosafety guidance may be difficult as these guidelines, largely based on practices in research laboratories, do not always correspond to the unique clinical laboratory environments and their specialized equipment and processes. We retrospectively describe the biosafety gaps and opportunities for improvement in the areas of risk assessment and management; automated and manual laboratory disciplines; specimen collection, processing, and storage; test utilization; equipment and instrumentation safety; disinfection practices; personal protective equipment; waste management; laboratory personnel training and competency assessment; accreditation processes; and ethical guidance. Also addressed are the unique biosafety challenges successfully handled by a Texas community hospital clinical laboratory that performed testing for patients with Ebola without a formal biocontainment unit. The gaps in knowledge and practices identified in previous and ongoing outbreaks demonstrate the need for collaborative, comprehensive solutions to improve clinical laboratory biosafety and to better combat future emerging infectious disease outbreaks.

Does point-of-care testing in general practice for leucocyte and differential count change use of antimicrobial medicines? A pilot study

Diagnostic uncertainty when considering prescription of antimicrobials ('antibiotics') in primary care contributes to the major problem of microbial resistance. We conducted a feasibility evaluation of rapid testing for leucocyte and differential count in two urban general practices, surveying the GPs online and interviewing them. GPs reported that the machines were easy to use, the test results influenced their care and they would adopt the system if costs were off-set. Feasibility, acceptability and perceived benefit justify a randomised trial to test the effect on antibiotic prescribing rates and quality of care, with an economic evaluation to inform the cost-benefit.

Development of a Mobile Laboratory for Sudden Onset Disasters

OBJECTIVES

Clinical diagnostics in sudden onset disasters have historically been limited. We set out to design, implement, and evaluate a mobile diagnostic laboratory accompanying a type 2 emergency medical team (EMT) field hospital.

METHODS

Available diagnostic platforms were reviewed and selected against in field need. Platforms included HemoCue301/WBC DIFF, i-STAT, BIOFIRE FILMARRAY multiplex rt-PCR, Olympus BX53 microscopy, ABO/Rh grouping, and specific rapid diagnostic tests. This equipment was trialed in Katherine, Australia, and Dili, Timor-Leste.

RESULTS

During the initial deployment, an evaluation of FilmArray tests was successful using blood culture identification, gastrointestinal, and respiratory panels. HemoCue301 (n = 20) hemoglobin values were compared on Sysmex XN 550 (r = 0.94). HemoCue WBC DIFF had some variation, dependent on the cell, when compared with Sysmex XN 550 (r = 0.88-0.16). i-STAT showed nonsignificant differences against Vitros 250. Further evaluation of FilmArray in Dili, Timor-Leste, diagnosed 117 pathogens on 168 FilmArray pouches, including 25 separate organisms on blood culture and 4 separate cerebrospinal fluid pathogens.

CONCLUSION

This mobile laboratory represents a major advance in sudden onset disaster. Setup of the service was quick (< 24 hr) and transport to site rapid. Future deployment in fragmented health systems after sudden onset disasters with EMT2 will now allow broader diagnostic capability.

The accuracy of a point of care measurement of activated partial thromboplastin time in intensive care patients

Point of care (POC) devices are increasingly being used in intensive care units to obtain faster results. Data are limited on the performance of these devices in critically ill patients, especially those on heparin infusion. The objective of this study was to assess the agreement between POC activated partial thromboplastin time (APTT) and laboratory APTT results in patients on heparin infusion and to determine its impact on the clinical decisions regarding heparin dosage. We screened all patients admitted to the intensive care unit (ICU) at St George Hospital, Sydney, over a 7-month period and enrolled those who were receiving intravenous heparin infusion. We measured APTT by two methods: bedside POC test (Hemochron Junior Signature Plus) and central laboratory method (STA analyser). We used the Bland-Altman method to test the statistical agreement between the two measurements and Cohen's kappa statistic to test the clinical agreement regarding heparin dosing decision. A total of 176 paired samples from 44 patients (mean age 63 years, 64% males, mean APACHE 18) were analysed. The mean turnaround time for the point of care APTT result was significantly shorter than the central laboratory result (5.0±0.2 min vs 64.6±2.7 min, p<0.0001). Despite the statistically significant correlation, the overall agreement tested by the Bland-Altman method was poor. The 95% limits of agreement were widest (-27.266 to 64.791) and mean percentage bias was highest (24%) for the comparison between POC APTT using citrated blood and laboratory APTT. When POC APTT results of less than 90 seconds using whole blood were compared to laboratory APTT results, the limits of the agreement became narrower (-23.243 to 28.419), and the mean percentage bias decreased to 5%. The agreement between clinical decisions regarding heparin dosage based on the two methods was poor for plain and citrated blood (kappa 0.35 and 0.11, respectively). The POC APTT results were not sufficiently accurate for use in patients on heparin infusion compared to laboratory APTT assay.

Point-of-care blood eosinophil count in a severe asthma clinic setting

BACKGROUND

One of the main severe asthma phenotypes is severe eosinophilic or eosinophilic refractory asthma for which novel biologic agents are emerging as therapeutic options. In this context, blood eosinophil counts are one of the most reliable biomarkers.

OBJECTIVE

To evaluate the performance of a point-of-care peripheral blood counter in a patients with severe asthma.

METHODS

The blood eosinophil counts of 76 patients with severe asthma were evaluated by point-of-care and standard analyzers.

RESULTS

A significant correlation between blood eosinophils assessed by the 2 devices was found (R² = 0.854, P < .001); similar correlations were found also for white blood cells, neutrophils, and lymphocytes. The point-of-care device had the ability to predict blood eosinophil cutoffs used to select patients for biologic treatments for severe eosinophilic asthma and the ELEN index, a composite score useful to predict sputum eosinophilia.

CONCLUSION

The results of our study contribute to the validation of a point-of-care device to assess blood eosinophils and open the possibility of using this device for the management of severe asthma management.

The HemoCue WBC DIFF system could be used for leucocyte and neutrophil counts but not for full differential counts

AIM

The aim of this study was to evaluate the HemoCue WBC DIFF system for point of care testing of fingerstick samples from paediatric patients.

METHODS

We analysed 158 white blood cell counts on both the point of care HemoCue WBC DIFF instrument and the Cell Dyn Sapphire cell counter used by our central laboratory and compared the results. The measurements were performed using fingerstick samples drawn by nurses working in paediatric emergency and paediatric oncology units.

RESULTS

There was good agreement between the two instruments for white blood cell and neutrophil counts. The correlation was weaker for lymphocytes, and the correlations were poor for monocytes and eosinophils. The HemoCue WBC DIFF flagged 56 of the 148 capillary drawn samples as abnormal, but none of the 10 venously collected samples. Only two of the flagged samples differed significantly between the instruments, with regard to the cell counts.

CONCLUSION

The correlations between the white blood cell counts and neutrophil counts in this real-life study were good enough to diagnose children in emergency department and oncology unit settings. However, the high number of pathological flags from fingerstick samples, which made reruns necessary, limited the usefulness of the instrument.

Systematic review of the role of angiopoietin-1 and angiopoietin-2 in Plasmodium species infections: biomarkers or therapeutic targets?

BACKGROUND

Levels of both angiopoietin-1 (Ang-1) and angiopoietin-2 (Ang-2) correlate with malaria disease severity and are proposed as biomarkers and possible therapeutic targets. To establish their role in malaria, a systematic review was performed of the literature on Ang-1 and Ang-2 with regard to their potential as biomarkers in malaria and discuss their possible place in adjuvant treatment regimens.

METHODS

Ten electronic databases were systematically searched to identify studies investigating Ang-1 and Ang-2 in human and murine malaria in both clinical and experimental settings. Information about the predictive value of Ang-1 and Ang-2 for disease severity and their regulatory changes in interventional studies were extracted.

RESULTS

Some 579 studies were screened; 26 were included for analysis. In all five studies that determined Ang-1 levels and in all 11 studies that determined Ang-2 in different disease severity states in falciparum malaria, a decline in Ang-1 and an increase of Ang-2 levels was associated with increasing disease severity. All nine studies that determined angiopoietin levels in Plasmodium falciparum patients to study their ability as biomarkers could distinguish between multiple disease severity states; the more the disease severity states differed, the better they could be distinguished. Five studies differentiating malaria survivors from non-survivors with Ang-2 as marker found an AUROC in a range of 0.71-0.83, which performed as well or better than lactate. Prophylactic administration of FTY720, rosiglitazone or inhalation of nitric oxide (NO) during malaria disease in mice resulted in an increase in Ang-1, a decrease in Ang-2 and an increased survival. For rosiglitazone, a decrease in Ang-2/Ang-1 ratio was observed after post-infection treatment in mice and humans with malaria, but for inhalation of NO, an effect on Ang-1 and survival was only observed in mice.

CONCLUSION

Both Ang-1 and Ang-2 levels correlate with and can distinguish between malaria disease severity states within the group of malaria-infected patients. However, distinct comparisons of disease severity states were made in distinct studies and not all distinctions made had clinical relevance. Changes in levels of Ang-1 and Ang-2 might also reflect treatment effectiveness and are promising therapeutic targets as part of multi-targeted therapy.

Laboratory testing in management of patients with suspected Ebolavirus disease: infection control and safety

If routine laboratory safety precautions are followed, the risk of laboratory-acquired infection from handling specimens from patients with Ebolavirus disease (EVD) is very low, especially in the early 'dry' stage of disease. In Australia, border screening to identify travellers returning from EVD-affected west African countries during the 2014-2015 outbreak has made it unlikely that specimens from patients with unrecognised EVD would be sent to a routine diagnostic laboratory. Australian public health and diagnostic laboratories associated with hospitals designated for the care of patients with EVD have developed stringent safety precautions for EVD diagnostic and other tests likely to be required for supportive care of the sickest (and most infectious) patients with EVD, including as wide a range of point-of-care tests as possible. However, it is important that the stringent requirements for packaging, transport and testing of specimens that might contain Ebolavirus--which is a tier 1 security sensitive biology agent--do not delay the diagnosis and appropriate management of other potentially serious but treatable infectious diseases, which are far more likely causes of a febrile illness in people returning from west Africa. If necessary, urgent haematology, biochemistry and microbiological tests can be performed safely, whilst awaiting the results of EVD tests, in a PC-2 laboratory with appropriate precautions including: use of recommended personal protective equipment (PPE) for laboratory staff; handling any unsealed specimens in a class 1 or II biosafety cabinet; using only centrifuges with sealed rotors; and safe disposal or decontamination of all used equipment and laboratory waste.

An electrochemiluminescence sensor with dual signal amplification of Ru(bpy)32+based on PtNPs and glucose dehydrogenase for diagnosis of gas gangrene

Gas gangrene is a bacterial infection that produces gas in tissues in gangrene.C. perfringenswith alpha-toxin plays a key role in gas gangrene. Detection ofC. perfringensis highly important in clinical diagnosis of gas gangrene.