Challenges of In Vitro Glycation when Producing Blood Materials for Hemoglobin A1C Immunoassays.

BACKGROUND: Blood materials are essential for quality control and assurance of hemoglobin A1C (HbA1C) measurements. This study presents an optimal condition for in vitro glycation to prepare blood materials for HbA1C with desired high HbA1C content and commutable with two immunoassays. METHODS: Washed erythrocytes were adjusted to a hematocrit (Hct) of 50 - 55% and glycated in vitro at 37°C for up to 120 hours with various concentrations of D-glucose in phosphate buffer saline to prepare blood materials for HbA1C. After glycation in each condition, glycation of blood material was inhibited and HbA1C level was monitored. The HbA1c in blood materials from in vitro glycation was compared in terms of stability and commutability with blood materials from other preparation methods. RESULTS: Incubation of erythrocytes with 400 mM D-glucose for 15 hours at 37°C resulted in a significant increase (p < 0.001) of HbA1c in blood materials by at least 40% with a remaining Hct between 38% to 42%. Hemoglobin A1C in blood materials was stable at 3.8 ± 0.8°C for 70 days and during transport for 3 days (temperature ranges from 8.1 to 23.5°C), after inhibition by glucose concentration solution. Hemoglobin A1C values in blood materials from in vitro glycation were commutable between enzymatic and turbidimetric immunoassay. CONCLUSIONS: An optimal condition for in vitro glycation by incubation of erythrocytes with 400 mM D-glucose for 15 hours at 37 °C was able to generate HbA1C material with intact erythrocytes that is sufficiently stable and commutable between enzymatic and turbidimetric immunoassay. Therefore, this condition is suitable for the preparation of blood material for HbA1C immunoassays.

A fifty-locus phylogenetic analysis provides deep insights into the phylogeny of Tricholoma (Tricholomataceae, Agaricales).

As an ectomycorrhizal fungal genus that contains matsutake and other edible mushrooms, Tricholoma has great economic and ecological significance. However, the phylogenetic relationships within the genus remain unsettled. To clarify the infrageneric relationships of Tricholoma, including the identification of monophyletic subgenera and sections, three phylogenetic analyses were conducted employing single-locus (ITS), five-locus (ITS/ RPB2/EF-1α/MCM7/mtSSU) and 50-locus (45 single-copy orthologous genes plus the aforementioned ones) DNA nucleotide sequences. Our data indicated that ITS sequences could serve the species delimitation of Tricholoma in most cases and monophyletic groups recognition in some cases, and the five-locus dataset could resolve a section-level phylogeny of this genus, while the 50-locus dataset could clarify the delimitation of subgenera and settle the relationships among sections within this genus. A fifty-locus dataset was firstly employed to construct a robust phylogeny of Tricholoma. Based on this, a new infrageneric arrangement for the genus Tricholoma, with four subgenera, of which two are in accordance with the previous subgenera Pardinicutis and Sericeicutis, and eleven sections, is suggested. Subgenus Pardinicutis, occupying the basal position, only harbors sect. Pardinicutis, while the subg. Sericeicutis comprises sects. Lasciva and Sericella located at the sub-basal position with good support. Subgenus Terrea is newly erected here and consists of sect. Terrea, sect. Atrosquamosa and two as yet unnamed phylogenetic lineages. Besides an unnamed section-level lineage, subg. Tricholoma consists of sects. Genuina, Muscaria, Rigida, Tricholoma, Fucata and Matsutake, of which the two latter are newly proposed. The previously defined subg. Contextocutis is clustered within subg. Tricholoma and is a synonym of the latter. Tricholoma colossus, T. acerbum and their allies, which used to be allocated in sect. Megatricholoma (or genus Megatricholoma), are relocated to sect. Genuina since they form a strongly supported monophyletic group and share rusty or black spots on lamellae with other species in this section. Taxonomic descriptions of the new infrageneric taxa and a key to subgenera and sections of the genus Tricholoma are presented. Citation: Ding XX, Xu X, Cui YY, et al. 2023. A fifty-locus phylogenetic analysis provides deep insights into the phylogeny of Tricholoma (Tricholomataceae, Agaricales). Persoonia 50: 1-26. https://doi.org/10.3767/persoonia.2023.50.01.

Design of a single-tube, endpoint, linear-after-the-exponential-PCR assay for 17 pathogens associated with sepsis.

AIMS: The goal of this study was to construct a single-tube multiplex molecular diagnostic assay using linear-after-the-exponential (LATE)-PCR for the detection of 17 microbial pathogens commonly associated with septicaemia. METHODS AND RESULTS: The assay described here detects 17 pathogens associated with sepsis via amplification and analysis of gene-specific sequences. The pathogens and their targeted genes were: Klebsiella spp. (phoE); Acinetobacter baumannii (gyrB); Staphylococcus aureus (spa); Enterobacter spp. (thdF); Pseudomonas aeruginosa (toxA); coagulase-negative staphylococci (tuf), Enterococcus spp. (tuf); Candida spp. (P450). A sequence from an unidentified gene in Lactococcus lactis, served as a positive control for assay function. LATE-PCR was used to generate single-stranded amplicons that were analysed at endpoint over a wide range of temperatures in four fluorescent colours. Each target was detected by its pattern of hybridization to a sequence-specific low-temperature fluorescent probe derived from molecular beacons. CONCLUSIONS: All 17 microbial targets were detected in samples containing low numbers of pathogen genomes in the presence of high levels of human genomic DNA. SIGNIFICANCE AND IMPACT OF THE STUDY: This assay used new technology to achieve an advance in the field of molecular diagnostics: a single-tube assay for detection of pathogens commonly responsible for septicaemia.

Verification of monoplex and multiplex linear-after-the-exponential PCR gene-specific sepsis assays using clinical isolates.

AIMS: To verify monoplex and multiplex gene-specific linear-after-the-exponential polymerase chain reaction (LATE-PCR) assays for identifying 17 microbial pathogens (i.e., Klebsiella sp., Acinetobacter baumannii, Staphylococcus aureus, Enterobacter sp., Pseudomonas aeruginosa, coagulase negative staphylococci, Enterococcus sp., Candida sp.) commonly associated with septicaemia using clinical isolates. METHODS AND RESULTS: Clinical isolates of each target pathogen were collected from the University of California, Davis Medical Center (UCDMC) microbiology laboratory. Five microlitres (µl) of each culture suspension (1 × 10(8) CFU ml(-1) ) were added to 20 µl of monoplex mastermix. DNA extracted from clinical isolates was tested in multiplex. Monoplex assays demonstrated 100% sensitivity at this input level, except Enterobacter cloacae (2.7%), Ac. baumannii (57%) and Ps. aeruginosa (97.8%). All clinical isolates were positive in multiplex, with the exception of two Ac. baumannii, two Klebsiella oxytoca and two Candida parapsilosis isolates. CONCLUSIONS: Sixteen pathogens can be identified by monoplex LATE-PCR assays with sensitivities ≥ 97.8%. The multiplex assay demonstrated 91.4% sensitivity when tested with DNA extracted from 70 different target strains. SIGNIFICANCE AND IMPACT OF THE STUDY: This study demonstrates the potential of LATE-PCR to serve as an adjunct to culture if the reagents are optimized for sensitivity. Results warrant further testing through analytical and clinical validation of the multiplex assay.

Patterns of interaction between Populus Esch5 and Piriformospora indica: a transition from mutualism to antagonism.

Piriformospora indica (Sebacinaceae, Basidiomycota) is an axenically cultivable, plant growth promoting root endophyte with a wide host range, including Populus. Rooting of Populus Esch5 explants started within 6 days after transfer to WPM medium. If such plantlets with roots were inoculated with P. indica, there was an increase in root biomass, and the number of 2nd order roots was increased significantly. A totally different observation was recorded when the explants were placed into WPM with pre-grown P. indica. The interaction led to complete blocking of root production and severely inhibited plant growth. Additionally, branched aerial roots appeared which did not penetrate the medium. On contact with the fungal colony or the medium, the ends of the aerial roots became inflated. Prolonged incubation stimulated the fungus to colonize aerial parts of the plant (stem and leaves). Mycelium not only spread on the surface of the aerial parts, but also invaded the cortical tissues inter- and intracellularly. Detached Populus leaves remained vital for 4 - 5 weeks on sterile agar media or on AspM medium with pre-grown P. indica. When the fungus was pre-grown on culture media such as WPM, containing ammonium as the main source of nitrogen, leaves in contact with the cultures turned brownish within 4 - 12 h. Thereafter, the leaves bleached, and about one day later had become whitish. Thus, cultural conditions could alter the behaviour of the fungus drastically: the outcome of the interaction between plant and fungus can be directed from mutualistic to antagonistic, characterized by fungal toxin formation and extension of the colonization to Populus shoots.

Critical limits for emergency clinician notification at United States children's hospitals.

Critical results demand rapid patient evaluation, possibly followed by life-saving intervention. A national survey of children's hospitals determined the critical limits used for emergency notification of critical laboratory results. Mean low and high critical limits for children for the tests listed most frequently were as follows (millimoles per liter): glucose, 2.6 and 24.7; potassium, 2.8 and 6.4; calcium, 1.62 and 3.17; and sodium 121 and 156. For newborns, significantly different (P less than .01) critical limits were glucose, 1.8 and 18.2; and potassium, 7.8. Hematology mean critical limits for children included hemoglobin, 69 and 208 g/L; platelets, 53 and 916 x 10(9)/L; hematocrit, 0.20 and 0.62 L/L; and white blood cell counts, 2.1 and 42.9 x 10(9)/L. Critical limits for pH were 7.21 and 7.59; for PCO2, 21 and 66 mm Hg; and for PO2, 45 and 124 mm Hg. Important qualitative critical results included blasts on the blood smear and abnormal cerebrospinal fluid findings. In comparison with other medical centers, children's hospitals maintained tighter critical limits for surveillance of renal function, hemostasis dysfunction, and newborn hypokalemia. Use of these results to eliminate outliers can help reduce unnecessary statim notification and improve resource utilization for the acute diagnosis and treatment of critically ill newborns and children.

The laboratory-clinical interface: point-of-care testing.

POC testing provides an opportunity for clinicians and laboratorians to work together to consider how best to serve the patients within an individual institution. Each health system has unique characteristics relative to patient population, as well as a unique laboratory structure. If physicians, nurses, laboratorians, and pathologists work collaboratively, the best interests of patients will be served. In some institutions that cater to specific patient groups, POC testing may offer clear and distinct advantages. In other institutions with sophisticated transport systems and established rapid response capabilities, the quality resulting from central laboratory testing may outweigh any advantages of bedside testing. Clearly, attention to regulatory issues, QC issues, the importance of proper documentation, proficiency testing, performance enhancement, and cost-effectiveness is requisite. As the technology for diagnostic testing advances through more microcomputerization, microchemistry, and enhanced test menus, the concept of POC testing will need perpetual revisiting. We hope that the information provided here will aid clinicians, laboratorians, and administrators in their quest to best serve their patients.

Management by objectives for the academic medical center.

Management by Objectives (MBO) is results-oriented, participatory management, which is appropriate for the current era of keen competition for resources. MBO was installed in the author's institution in clinical laboratory divisions meeting prerequisites and fit the system to the local management environment. The results were decidedly positive. Benefits included improved communication, organizational clarity, planning for deadlines, motivation of participants, work load distribution, and productivity. Projects were easier to visualize, track, and coordinate. A natural review cycle of three to four months evolved, with general review twice a year. MBO worked best with one- to two-year-long projects involving problem solving and innovation. The author expects maturity of his MBO application within three years. He recommends MBO for other academic medical center laboratories, provided executive management commits the necessary time and resources to install MBO carefully as a relatively loose, locally administered form of management philosophy, rather than management technology.

Guidelines for point-of-care testing. Improving patient outcomes.

Whole-blood biosensors and point-of-care testing created a unique paradigm in medical diagnostics in the 1980s, when liver and heart transplant centers, as well as operating rooms and other critical care areas implemented whole-blood analysis to provide rapid test results in 2 to 5 minutes. Rising expectations, patient-focused hospitals, and managed care intensify the need for immediate decisions at the point of care. The guidelines promote consensus priorities, multidisciplinary teamwork, fiscal coordination, and collaborative practice during this phase of rapid change. Four primary principles and accompanying guideline objectives are optimization (patient outcomes, medical linkages, integrated diagnostic synthesis, therapeutic turnaround time, test clusters, and critical limits), hybridization (strategic modalities, economic effectiveness, and testing --> monitoring), quality (quality improvement, clinical performance, risk reduction and academics and accreditation), and consistency (results communication and error minimization, and reference intervals and standardization). Whole-blood analysis and point-of-care testing help facilitate temporal optimization, optimize diagnostic-therapeutic processes, and improve patient outcomes in critical care.

Application of Program Evaluation and Review Technic (PERT) to laboratory research and development planning.

Software for the personal computer dramatically changes the ease with which managers of research and development can use network planning to guide projects to completion in the academic medical center setting. A case study of the use of the Critical Path Method (CPM) and Project Evaluation and Review Technic (PERT) in planning and implementing transcutaneous pCO2 monitoring by a department of laboratory medicine illustrates the utility and efficiency of these network planning technics. By means of iterative PERT analyses, the project was kept on track, despite an overly optimistic estimate of the completion date initially and intense demand by clinicians for use of the new monitoring technic in the management of premature infants with respiratory disease. Additionally, the iterative management approach improved project participants' expertise in estimating and meeting deadlines. Network planning is fully adaptable to the IBM PC or an equivalent microcomputer. This article summarizes several excellent project management software packages that have become available recently.

Theory of network planning for laboratory research and development.

Critical Path Method (CPM) and Program Evaluation and Review Technique (PERT) are quantitative network planning strategies that facilitate management of projects with many interrelated activities. They determine the minimum time necessary to complete a project and identify which activities are critical to achieving the minimum. PERT also incorporates probabilistic estimates of activity durations. This statistical approach is useful when planning a project entailing some uncertainty and allows one to calculate chances of finishing on time. CPM and PERT encourage participation of all key personnel in the planning process, effective fit between project variables and organizational structure, and optimization of resource allocation. Availability of several levels of sophistication make network planning flexible enough to be applied easily in laboratory research and development. Iterative refinement of network plans and time estimates in progressive steps of involvement with clinical colleagues augments the effectiveness of these technics in hospital settings.

The current and future status of critical care testing and patient monitoring.

Ex vivo and in vivo biosensor-based systems for patient monitoring now augment in vitro point-of-care testing, a paradigm currently in the explosive phase. As new technologies arise, so do opportunities for laboratory professionals. First, the laboratory consultant or clinical pathologist can contribute substantially to our understanding of temporal optimization and the role of diagnostic testing in optimizing diagnostic-therapeutic processes. Clarification of these facilitates wise selection of alternative testing modalities, test clusters, and instrument formats. Second, the laboratory professional is a natural member of a performance team that can help optimize outcomes and assure the quality of point-of-care testing. Explicit site-specific performance criteria for accuracy, precision, response time, and test clusters are essential and can only be established and accomplished jointly with clinicians. Third, clinical integration requires practice guidelines and care paths. These can help determine how, when, and where point-of-care testing should be implemented. Finally, global outcomes optimization calls for the input of those professionals who are most familiar with the economics of diagnostic testing, the challenges of point-of-care testing, and the best clinical benefits of in vitro, ex vivo, and in vivo biosensor-based systems in critical care and other settings.

Effects of drugs on glucose measurements with handheld glucose meters and a portable glucose analyzer.

Thirty drugs used primarily in critical care and hospital settings were tested in vitro to observe interference on glucose measurements with 6 hand-held glucose meters and a portable glucose analyzer. Paired differences of glucose measurements between drug-spiked samples and unspiked control samples were calculated to determine bias. A criterion of +/- 6 mg/dL was used as the cutoff for interference. Ascorbic acid interfered with the measurements on all glucose devices evaluated. Acetaminophen, dopamine, and mannitol interfered with glucose measurements on some devices. Dose-response relationships help assessment of drug interference in clinical use. High dosages of these drugs may be given to critically ill patients or self-administered by patients without medical supervision. Package inserts for the glucose devices may not provide adequate warning information. Hence, we recommend that clinicians choose glucose devices carefully and interpret results cautiously when glucose measurements are performed during or after drug interventions.

Monitoring of transcutaneous carbon dioxide tension.

The authors studied the analytic and clinical characteristics of transcutaneous carbon dioxide monitoring in acutely ill NICU infants. Most infants were premature. The authors used both developmental and commercially available equipment. Monitoring was performed at temperature settings of 44 degrees C. With commercially available equipment, it was found that the least-squares linear regression relationship (r = 0.86, Sy.x = 12.9 torr, n = 100 patients) between transcutaneous PCO2 (y) and arterial PCO2 (x) was: y = -2.8 + (1.86)(x) (in torr). Calibration drift was unacceptably large in about 10% of the 500 monitoring sessions performed. Therefore, the authors conclude that transcutaneous PCO2 monitoring is most appropriate for following short-term trends in PCO2 over a period of one to three hours. Continuous transcutaneous PCO2 monitoring was most useful clinically after extubation when the objectives were careful observation for changes in PCO2 and prevention of reintubation.

Monitoring of ionized calcium during human hepatic transplantation. Critical values and their relevance to cardiac and hemodynamic management.

During human hepatic transplantation, ionized calcium (ICa) measured in whole blood with an ion-selective electrode varied greatly from ICa predicted from total calcium (TCa), protein, albumin, and pH, by means of recently published nomograms. Measurement of ICa was necessary because the interaction of citrate in transfused blood and calcium chloride (administered to offset citrate binding) caused large variations in TCa. During hepatic transplantation, ICa and electrolyte measurements were obtained at approximately 15-minute intervals or more frequently if indicated by changing cardiac status. In one patient, hemodynamic instability was accompanied by a large decrease in ICa, which then was followed by cardiac arrest aggravated by myocardial depression from inadequate ICa. Cardiovascular phenomena associated with ionized hypocalcemia suggest that the critical value for ICa should be no more than 0.4 mmol/L (1.6 mg/dL) below the reference range mean. The authors propose critical limits for ICa and discuss their significance in clinical management of tetany, hypotension, arrythmias, and cardiac arrest.

Surface pH of the medial gastrocnemius and soleus muscles during hemorrhagic shock and ischemia.

Surface pH (SpH) responses of muscles of different fiber type composition were determined in sodium pentobarbital-anesthetized rabbits by comparison of the medical gastrocnemius (MG) and soleus (S) muscles. With hemorrhagic shock, S SpH decreased to 7.24 +/- 0.04 (mean +/- SD, P much less than 0.001) and MG SpH to 7.05 +/- 0.13 (P much less than 0.001). The mean of paired difference in SpH decrease (PDD) was 0.20 +/- 0.14 (P less than 0.002). With 1 hour of arterial ischemia, S SpH increased 0.02 +/- 0.03 (P less than 0.06) initially; overall, it decreased 0.17 +/- 0.07 (P much less than 0.001) to 7.24 +/- 0.09. The MG SpH decreased 0.49 +/- 0.24 (P much less than 0.001) to 6.90 +/- 0.23. The mean PDD was 0.32 +/- 0.22 (P less than 0.001). With 2 hours of arterial ischemia, S SpH increased 0.03 +/- 0.04 (P less than 0.05) initially; overall, it decreased 0.46 +/- 0.18 (P much less than 0.001) to 6.95 +/- 0.17. The MG SpH decreased 0.74 +/- 0.23 (P much less than 0.001) to 6.66 +/- 0.23. The mean PDD was 0.28 +/- 0.14 (P less than 0.001). Four of the 10 MG responses in the 2-hour arterial ischemia group were irreversible. SpH responses correlated with fiber type compositions. Initial increases in S SpH demonstrate that SpH does not invariably decrease during ischemia (as formerly assumed) and represent a potentially false negative clinical response. The large decrease in MG SpH shows that a highly glycolytic muscle will give the most sensitive indicator of reduced perfusion. Assessment of reperfusion may be problematic because of irreversible changes in SpH after prolonged ischemia. Conversely, SpH measurements may help identify regions of irreversibly damaged skeletal muscle, particularly those with mainly glycolytic fibers.

Oxygen effects on glucose measurements with a reference analyzer and three handheld meters.

Oxygen may affect glucose meter and reference analyzer measurements. We evaluated the effects of changes in blood oxygen tension (Po2) on Accu-Chek Comfort Curve (Roche Diagnostics, Indianapolis, IN), Precision G, (Abbott Laboratories, Bedford, MA) and One Touch II (Lifescan, Milpitas, CA) glucose meter measurements, and on Yellow Springs Instruments (YSI) (Yellow Springs, OH) reference analyzer measurements. Venous blood drawn from healthy volunteers was adjusted to three glucose levels of 80, 200, and 400 mg/dL, each tonometered with six different Po2 levels (40, 80, 160, 240, 320, and 400 torr). To quantitate oxygen effects on reference analyzer measurements, glucose differences between test sample (Po2 changed) and control (Po2 80 torr) were calculated (YSItest-YSIcontrol). The threshold for determination of oxygen effects was +/-2 SD, where 2 SD was fro

Preventing medical errors in point-of-care testing: security, validation, safeguards, and connectivity..

OBJECTIVES: o prevent medical errors, improve user performance, and enhance the quality, safety, and connectivity (bidirectional communication) of point-of-care testing. PARTICIPANTS: Group A included 37 multidisciplinary experts in point-of-care testing programs in critical care and other hospital disciplines. Group B included 175 professional point-of-care managers, specialists, clinicians, and researchers. The total number of participants equaled 212. EVIDENCE: This study followed a systems approach. Expert specifications for prevention of medical errors were incorporated into the designs of security, validation, performance, and emergency systems. Additional safeguards need to be implemented through instrument software options and point-of-care coordinators. Connectivity will be facilitated by standards that eliminate deficiencies in instrument communication and device compatibility. Assessment of control features on handheld, portable, and transportable point-of-care instruments shows that current error reduction features lag behind needs. CONCENSUS PROCESS: Step 1: United States national survey and collation of group A expert requirements for security, validation, and performance. Step 2: Design of parallel systems for these functions. Step 3: Written critique and improvement of the error-prevention systems during 4 successive presentations to group B participants over 9 months until system designs stabilized into final consensus form. CONCLUSIONS: The consensus process produced 6 conclusions for preventing medical errors in point-of-care testing: (1) adopt operator certification and validation in point-of-care testing programs; (2) implement security, validation, performance, and emergency systems on existing and new devices; (3) require flexible, user-defined error-prevention system options on instruments as a prerequisite to federal licensing of new diagnostic tests and devices; (4) integrate connectivity standards for bidirectional information exchange; (5) preserve fast therapeutic turnaround time of point-of-care test results; and (6) monitor invalid use, operator competence, quality compliance, and other performance improvement indices to reduce errors, thereby focusing on patient outcomes.(Arch Pathol Lab Med. 2001;1307-1315)

The significance of ionized calcium in cardiac and critical care. Availability and critical limits at US medical centers and children's hospitals.

The clinical use of ionized calcium has increased since the recognition of its importance in cardiac and critical care medicine. However, more than half the general medical centers in the United States do not provide immediate testing of ionized calcium levels in patients in critical care settings, although indications for this test indicate that they should. The following objectives were used in this study: (1) to determine the availability of ionized calcium testing; (2) to document appropriate critical limits; and (3) to describe the significance of ionized hypocalcemia in cardiac and critical care. The participants were 100 medical centers and 40 children's hospitals in the United States. At medical centers, mean (+/- SD) critical limits were as follows: low, 0.82 +/- 0.14 mmol/L (3.29 +/- 0.56 mg/dL); and high, 1.55 +/- 0.19 mmol/L (6.21 +/- 0.76 mg/dL). At children's hospitals, mean critical limits were as follows: low, 0.85 +/- 0.13 mmol/L (3.41 +/- 0.52 mg/dL); and high, 1.53 +/- 0.11 mmol/L (6.13 +/- 0.44 mg/dL). In the past decade, the availability of ionized calcium testing increased dramatically. Now, 57%, 86%, 95%, and 100% of general hospitals, heart transplant centers, children's hospitals, and pediatric heart transplant centers, respectively, perform testing in house. Collective experience indicates that: (1) aggressive monitoring of ionized calcium prevents cardiac (and neurologic) catastrophes, (2) appropriate levels optimize cardiac function, and (3) calcium repletion is safest when based on acute trends measured directly in whole blood. Hospitals should provide rapid response testing needed during transplantation and massive transfusion and for the diagnosis and treatment of acute ionized hypocalcemia.

New whole-blood testing for laboratory support of critical care at cardiac transplant centers and US hospitals.

Whole-blood analytical techniques include ion-specific, substrate-specific, amperometric, and impedance electrodes. These allow direct measurement of critical analytes simultaneously in whole blood without centrifugation, resulting in a response time of 2 to 5 minutes. Cardiac transplantation centers rely heavily on whole-blood instruments to provide rapid response tests essential for cardiovascular management. A survey of 81 blood gas laboratories in 25 cardiac transplantation centers and 73 blood gas laboratories in 36 general hospitals showed an increase in testing for potassium, free calcium, and glucose by blood gas laboratories since 1982 and extensive use of satellite laboratories near areas serving critically ill patients. The following three recent developments are improving the availability of laboratory results: (1) direct whole-blood measurement is gaining acceptance, (2) instrumentation designed specifically for rapid critical care profiling is being used extensively, and (3) testing is moving closer to patients. These trends suggest a significant change in laboratory support of critical care in the United States.