Uso de la determinación transcutánea de co2 en pacientes con déficit de timidina quinasa 2 y costes de su uso en una consulta de ventilación mecánica no invasiva / Use of transcutaneous co2 determination in patients with thymidine kinase 2 deficit and costs of its use in a noninvasive mechanical ventilation consultation

Objetivo: Describir el uso de la capnografía transcutánea en una población adulta y pediátrica de pacientes con déficit de timidina quinasa 2 y hacer un estudio comparativo de costes de una determinación de gasometría arterial y capnografía en la población de nuestra consulta de VMNI. Metodología: Se realizó una anamnesis y unas pruebas funcionales respiratorias para valorar afectación de la musculatura respiratoria y calidad del sueño. Para determinar la hipoventilación, se midió la pCO2 transcutánea en vigilia y/o durante el sueño. Se realizó un estudio económico para comparar el coste de una determinación de ptcCO2 frente a la determinación mediante GSA. El estudio económico se realizó estimando la población total de pacientes que se valoraba en la consulta de VMNI de manera anual. Resultados: 9 pacientes con déficit de TK2 (4 adultos y 5 niños). A 4 pacientes se les realizó una poligrafía respiratoria basal. A la población pediátrica se les realizó un registro continuo de ptcCO2 con pulsioximetria anual. Se realizaron 4 registros con ptcCO2 y VMNI. Elcoste de la determinación de ptCO2 en comparación con la GSA fue de 6,29 euros frente a 5,37 euros. Conclusiones: La medición de la ptcCO2 es útil en la consulta de VMNI para la realización de medidas puntuales en la consulta como para monitorización continua durante el sueño. Con el uso que realizamos en nuestra consulta de la capnografía transcutánea, la determinación puntual de la pCO2 transcutánea es más económica que la realización de la GSA. (AU)

Objective: to describe the use of transcutaneous capnography in an adult and pediatric population of patients with Thymidine inase 2 deficiency and to compare the costs between blood gases by arterial gasometry (BGA) and capnography in our population. Material and methods: an anamnesis, and respiratory functional tests to assess respiratory muscle involvement, sleep quality were performed.To assess the presence of alveolar hypoventilation the determination of transcutaneous pCO2while awake and/or during sleepwas performed. An economic study has been done to compare the cost of a determination of ptcCO2 versus the determination by BGA. Results: 9 patients with TK2 deficiency (4 adults and 5 children). 4 patients underwent baseline respiratory polygraphy. The pediatric patients underwent at least one continuous recording of ptcCO2 with pulse oximetry each year.4 studies of ptcCO2 duringNIV were performed. The cost in the adult population of a punctual determination of pCO2 by BGA was 6,29 euros while for capnography was 5,37 euros. Conclusions: the measurement of ptcCO2 is useful in the consultation of NIV for the realization of specific measurements in the consultation as for continuous monitoring of this parameter. In our practice of transcutaneous capnography, the punctual determination of transcutaneous pCO2 is cheaper than the BGA. (AU)

Arterial blood gas as a prognostic indicator in patients with sepsis.

Abnormal arterial blood gas (ABG) among patients with sepsis is an important prognostic indicator. All-cause mortality was the highest among patients with respiratory acidosis (4/9 = 44.4%), followed by those having metabolic acidosis (3/8 = 37.5%). Median length of hospital and intensive care unit stay was 15.75 days and 6.25 days for those with abnormal ABG and 11 and 3.5 days among those with normal ABG. Median health-care expenditure at the time of discharge or death of the patient was the highest in patients with respiratory acidosis ($14,473) and least in patients with normal ABG ($3,384) (average expenditure among patients with abnormal ABG was [$10,059]).

Clinical, Operative, and Economic Outcomes of the Point-of-Care Blood Gases in the Nephrology Department of a Third-Level Hospital.

CONTEXT.­: Point-of-care testing allows rapid analysis and short turnaround times. To the best of our knowledge, the present study assesses, for the first time, clinical, operative, and economic outcomes of point-of-care blood gas analysis in a nephrology department. OBJECTIVE.­: To evaluate the impact after implementing blood gas analysis in the nephrology department, considering clinical (differences in blood gas analysis results, critical results), operative (turnaround time, elapsed time between consecutive blood gas analysis, preanalytical errors), and economic (total cost per process) outcomes. DESIGN.­: A total amount of 3195 venous blood gas analyses from 688 patients of the nephrology department before and after point-of-care blood gas analyzer installation were included. Blood gas analysis results obtained by ABL90 FLEX PLUS were acquired from the laboratory information system. Statistical analyses were performed using SAS 9.3 software. RESULTS.­: During the point-of-care testing period, there was an increase in blood glucose levels and a decrease in pCO2, lactate, and sodium as well as fewer critical values (especially glucose and lactate). The turnaround time and the mean elapsed time were shorter. By the beginning of this period, the number of preanalytical errors increased; however, no statistically significant differences were found during year-long monitoring. Although there was an increase in the total number of blood gas analysis requests, the total cost per process decreased. CONCLUSIONS.­: The implementation of a point-of-care blood gas analysis in a nephrology department has a positive impact on clinical, operative, and economic terms of patient care.

Cost effectiveness of universal umbilical cord blood gas and lactate analysis in a tertiary level maternity unit.

OBJECTIVE: There is an increasing body of literature supporting universal umbilical cord blood gas analysis (UCBGA) into all maternity units. A significant impediment to UCBGA's introduction is the perceived expense of the introduction and associated ongoing costs. Consequently, this study set out to conduct the first cost-effectiveness analysis of introducing universal UCBGA. METHODS: Analysis was based on 42,100 consecutive deliveries ≥23 weeks of gestation at a single tertiary obstetric unit. Within 4 years of UCBGA's introduction there was a 45% reduction in term special care nursery (SCN) admissions >2499 g. Incurred costs included initial and ongoing costs associated with universal UCBGA. Averted costs were based on local diagnosis-related grouping costs for reduction in term SCN admissions. Incremental cost-effectiveness ratio (ICER) and sensitivity analysis results were reported. RESULTS: Under the base-case scenario, the adoption of universal UCBGA was less costly and more effective than selective UCBGA over 4 years and resulted in saving of AU$641,532 while adverting 376 SCN admissions. Sensitivity analysis showed that UCBGA was cost-effective in 51.8%, 83.3%, 99.6% and 100% of simulations in years 1, 2, 3 and 4. These conclusions were not sensitive to wide, clinically possible variations in parameter values for neonatal intensive care unit and SCN admissions, magnitude of averted SCN admissions, cumulative delivery numbers, and SCN admission costs. CONCLUSIONS: Universal UCBGA is associated with significant initial and ongoing costs; however, potential averted costs (due to reduced SCN admissions) exceed incurred costs in most scenarios.

A randomised clinical trial on cardiotocography plus fetal blood sampling versus cardiotocography plus ST-analysis of the fetal electrocardiogram (STAN) for intrapartum monitoring.

BACKGROUND: Cardiotocography (CTG) is worldwide the method for fetal surveillance during labour. However, CTG alone shows many false positive test results and without fetal blood sampling (FBS), it results in an increase in operative deliveries without improvement of fetal outcome. FBS requires additional expertise, is invasive and has often to be repeated during labour. Two clinical trials have shown that a combination of CTG and ST-analysis of the fetal electrocardiogram (ECG) reduces the rates of metabolic acidosis and instrumental delivery. However, in both trials FBS was still performed in the ST-analysis arm, and it is therefore still unknown if the observed results were indeed due to the ST-analysis or to the use of FBS in combination with ST-analysis. METHODS/DESIGN: We aim to evaluate the effectiveness of non-invasive monitoring (CTG + ST-analysis) as compared to normal care (CTG + FBS), in a multicentre randomised clinical trial setting. Secondary aims are: 1) to judge whether ST-analysis of fetal electrocardiogram can significantly decrease frequency of performance of FBS or even replace it; 2) perform a cost analysis to establish the economic impact of the two treatment options. Women in labour with a gestational age > or = 36 weeks and an indication for CTG-monitoring can be included in the trial. Eligible women will be randomised for fetal surveillance with CTG and, if necessary, FBS or CTG combined with ST-analysis of the fetal ECG. The primary outcome of the study is the incidence of serious metabolic acidosis (defined as pH < 7.05 and Bdecf > 12 mmol/L in the umbilical cord artery). Secondary outcome measures are: instrumental delivery, neonatal outcome (Apgar score, admission to a neonatal ward), incidence of performance of FBS in both arms and cost-effectiveness of both monitoring strategies across hospitals. The analysis will follow the intention to treat principle. The incidence of metabolic acidosis will be compared across both groups. Assuming a reduction of metabolic acidosis from 3.5% to 2.1 %, using a two-sided test with an alpha of 0.05 and a power of 0.80, in favour of CTG plus ST-analysis, about 5100 women have to be randomised. Furthermore, the cost-effectiveness of CTG and ST-analysis as compared to CTG and FBS will be studied. DISCUSSION: This study will provide data about the use of intrapartum ST-analysis with a strict protocol for performance of FBS to limit its incidence. We aim to clarify to what extent intrapartum ST-analysis can be used without the performance of FBS and in which cases FBS is still needed. TRIAL REGISTRATION NUMBER: ISRCTN95732366.

Evaluation of relationship between arterial and venous blood gas values in the patients with tricyclic antidepressant poisoning.

INTRODUCTION: Determination of arterial blood gas (ABG) values is essential in the evaluation of patients with TCA poisoning. The relationship between arterial and venous blood gas pH has not been established in TCA poisoning. In TCA poisoning, blood vessels vasodilatation due to antidepressant-induced alpha-blockade and also metabolic acidosis may lead to arterialization of venous blood, which in turn enhances the relationship between ABG and VBG parameters. Therefore this study was designed to evaluate the relationship between ABG and VBG pH values in TCA poisoned patients. METHODS: This prospective study was performed in the Poisoning Emergency Department of Noor Hospital, Isfahan, Iran. Samples for arterial and venous blood gas analysis were obtained during initial evaluation of TCA-poisoned patients and 30 min after treatment with sodium bicarbonate. The venous blood gas samples were collected with samples for other blood tests at the time of intravenous line insertion. Laboratory data were recorded on a database form initiated in the emergency department and analyzed by paired student t-test. The degree of agreement between the arterial and venous pH measurements was evaluated by Bland and Altman method. RESULTS: Data from 50 TCA-poisoned patients were analyzed. There were significant differences between mean differences of ABG and VBG parameter values on the initial evaluation. There was also a relationship between arterial and venous pH on the initial evaluation. CONCLUSION: In TCA poisoning, the peripheral venous pH measurement is a valid and reliable substitute for arterial pH.

Cost: benefit of point-of-care blood gas analysis vs. laboratory measurement during stabilization prior to transport.

INTRODUCTION: This study was conducted to determine whether point-of-care testing, using the iSTAT Portable Clinical Analyzer, would reduce time at the referring hospital required to stabilize ventilated pediatric patients prior to interfacility, air-medical transport. METHODS: The following data were collected prospectively: (1) When a blood gas analysis was ordered; (2) If it was necessary to call in a technician; (3) Waiting time for blood to be drawn; and (4) Waiting time for results. The cost-efficacy of point-of-care testing was calculated based on: (1) Three minutes for a transport team member to draw a sample and obtain a result using the iSTAT (unit cost 8,000 CDN dollars); (2) Lab technician call-back (minimum two hours at 90 dollars); (3) Paramedic overtime (by the minute at 49 dollars/hour); and (4) Cost of charter aircraft wait time (200 dollars per hour) for every hour beyond four hours. RESULTS: Data were collected on 46 ventilated patients over a three month period. A blood gas analysis was ordered on 35 patients. Laboratory technicians were called in for 17 (49%). For 12 (34%) patients, there was a wait for the sample to be drawn, and for 23 (66%), there was a wait for results to become available. Total time waiting to obtain laboratory gases was 526 minutes compared with a calculated 105 minutes using point-of-care testing. An iSTAT cartridge cost of 420 dollars would not have been different from laboratory costs. Cost-saving on technician callback (1,530 dollars), paramedic overtime (690 dollars) and aircraft time waiting charges (2,000 dollars) would have totaled (4,220 dollars). From this study, the cost of point-of-care equipment could be recouped in 101 patients if aircraft charges apply or 192 patients if no aircraft costs are involved. For 11 cases, ventilator adjustments were made subsequently during transport, and for six patients, point-of-care testing, if in place, would have been used to optimize transport care. CONCLUSION: The data from the present study indicate significant cost-efficacy from use of this technology to reduce stabilization times, and support the potential to improve quality of care during air medical interfacility transport.

[Point care testing in blood gas and electrolyte analysis : examples of implementation and cost analysis]. / Gazométrie et électrolytes sanguins délocalisés: exemples d'organisation et évaluation économique.

An increasing proportion of laboratories manage and organize point of care testing (POCT). The purpose of this article is to describe the implementation made at Lariboisière hospital for three remote blood gas analysers. The most important aspect in this achievement is the comprehensive computerization, making possible real time management of POCT in agreement with the Point of Care unit Management team. In addition, we present a running cost analysis, comparing three Blood gas systems (Rapidlab860, Rapidpoint 400--Bayer Diagnostics and i-Stat Abbott Diagnostics). This study indicates that cost per test hugely varies based on the daily sample demand. In addition to analytical and organizational items, the clinical chemist should consider the testing demand as a key factor in choosing an analyser for POCT.

Quality improvement report: Linking guideline to regular feedback to increase appropriate requests for clinical tests: blood gas analysis in intensive care.

PROBLEM: Need to decrease the number of requests for arterial blood gas analysis and increase their appropriateness to reduce the amount of blood drawn from patients, the time wasted by nurses, and the related cost. DESIGN: Assessment of the impact of a multifaceted intervention aimed at changing requests for arterial blood gas analysis in a before and after study. BACKGROUND AND SETTING: Twenty bed surgical intensive care unit of a tertiary university affiliated hospital, receiving 1500 patients per year. KEY MEASURES FOR IMPROVEMENT: Number of tests per patient day, proportion of tests complying with current guideline, and safety indicators (mortality, incident rate, length of stay). Comparison of three 10 month periods corresponding to baseline, pilot (first version of the guideline), and consolidated (second version of the guideline) periods from March 1997 to August 1999. STRATEGIES FOR CHANGE: Multifaceted intervention combining a new guideline developed by a multidisciplinary group, educational sessions, and monthly feedback about adherence to the guideline and use of blood gas analysis. EFFECTS OF CHANGE: Substantial decrease in the number of tests per patient day (from 8.2 to 4.8; P<0.0001), associated with increased adherence to the guideline (from 53% to 80%, P<0.0001). No significant variation of safety indicators. LESSONS LEARNT: A multifaceted intervention can substantially decrease the number of requests for arterial blood gas analysis and increase their appropriateness without affecting patient safety.

Acute care testing. Blood gases and electrolytes at the point of care.

The standard turnaround time for acute care laboratory testing in tertiary care institutions is typically less than 15 minutes for blood gas or electrolyte values. From a clinical perspective, however, the desirable turnaround time is more on the order of 5 minutes, and this is technically achievable. The 15-minute standard can be met with strategically located STAT laboratories. To achieve a turnaround time of 5 minutes, it is necessary to move the "laboratory" closer to the patient and to have more than one instrument available. This latter configuration is called near or bedside patient testing. Why the 5-minute standard is not used universally throughout the nation is probably related to differing perspectives on "cost" and "quality." As manufacturers, hospitals and laboratories address the issue of rapid turnaround time in acute care settings, the 5-minute standard may become more widespread. Direct costs have been decreasing as more manufacturers enter the market for acute care testing. The overall quality is also improving, not only in the engineering features built into the instruments, but also as nonlaboratory staff gain skill in performing the testing. As more sites implement POCT, standards and guidelines for managing testing outside of the laboratory are being established. Solutions to preanalytic problems are being developed and implemented. POCT testing for blood gases and electrolytes was once considered to lie in the future but is now commonplace and may one day become the standard of care.

The rise and fall of i-STAT point-of-care blood gas testing in an acute care hospital.

In response to a $350,000 laboratory budget cut and closure of an intensive care unit-based laboratory and a desire to maintain turnaround times of 10 minutes or less, a multidisciplinary group developed and implemented point-of-care (POC) testing. Only blood gases (pH, PO2, and PCO2) and ionized calcium values were deemed essential stat tests. Three commercially available POC blood gas devices were evaluated; all yielded results comparable to in-house reference methods. The 1 device with a US Food and Drug Administration-approved method for ionized calcium testing and with an existing interface for laboratory information systems was selected. Fiscal analysis predicted annual savings of approximately $225,000. POC blood gas analysis was implemented in April 1996 coincident with closure of the intensive care unit-based laboratory. Clinical laboratories and POC blood gas test volumes remained constant through August 1998; in contrast, the number of ionized calcium tests decreased dramatically after April 1996. In August 1998, clinically significant (i.e., artificial ventilation parameters would have been altered based on test results) discrepant PCO2 values were observed sporadically and noted only with patient specimens, not with commercial controls or electronic simulators. Because investigation failed to identify the cause, use of the POC device was discontinued in September 1998.

[Four new instrument for blood gas analysis are tested: handy cassettes for easier use]. / Fyra nya instrument för analys av blodgaser testade: behändiga kassetter skall ge bättre användarvänlighet.

An entirely new type of blood gas analyser has made its way into the marketplace, to be used, for example, in emergency rooms, intensive care units, ambulances, and bedside with quarantined patients in infectious diseases units. The instruments reviewed here employ new miniaturised analysis circuitry, integrated into the cassette on which the blood sample is applied. These instruments are designed for use by care-givers without specific laboratory training. Four point-of-care blood gas analysers are tested: OPTI 1 (AVL), I-STAT (HP), IRMA (Infiniti) och ABL 70 (Radiometer).

Estimating costs and turnaround times: presenting a user-friendly tool for analyzing costs and performance.

A review of the literature finds wide variation in the costs and turnaround times associated with central laboratories, satellite laboratories, and point-of-care testing. The greatest variation occurs when comparing options for blood gas and electrolyte testing. Some variation can be attributed to costing methods, but substantial variation arises from circumstances under which testing is undertaken in specific sites. These circumstances include the site-specific costs of resources used in testing, volumes of testing conducted, and performance requirements demanded by the users of laboratory information.

Cost analysis for decision support: the case of comparing centralized versus distributed methods for blood gas testing.

Distributed testing, performed in satellite laboratories or at the bedside, is proliferating within healthcare systems. Users prefer it, and it is fast and convenient. A quick look at marginal costs, however, suggests that cost differentials between distributed and centralized testing may be prohibitive. Sound decision making on the part of health system administrators requires a broader understanding of the costs and benefits of testing options. This study illustrates an approach to cost analysis for decision support where opportunity costs (the costs associated with the next best alternative) provide the basis for decision making. Health system administrators need to understand the opportunity costs involved in their decisions to avoid being misled by analyses that omit important cost elements from consideration. We describe approaches to determining the costs of "stat" laboratory testing options. The costs of various blood gas testing options are compared among a central blood gas laboratory, two satellite laboratories, and point-of-care analysis. Opportunity costs were determined by modeling the substitution of one testing process for another. The cost analysis finds that a judicious mix of alternate-site testing methods can generate annual savings of between $250,000 and $330,000, and at the same time reduce test reporting times. In other words, technology that superficially appears more costly can deliver better service with lower costs.

Screening for ketonemia in patients with diabetes.

STUDY OBJECTIVES: To determine the sensitivity and specificity of the urine ketone dip test as a screening test for ketonemia in hyperglycemic patients and to compare the performance of the urine ketone dip test with the anion gap and serum bicarbonate level. METHODS: This was a prospective study conducted in an urban, university-affiliated public hospital emergency department. Inclusion criteria consisted of (1) patients with known diabetes and hyperglycemia (glucose level>200 mg/dL) and any complaint of illness, or (2) patients with hyperglycemia and symptoms of undiagnosed diabetes mellitus. Urine ketone dip test, serum ketone, and electrolyte levels were determined on all subjects. Sensitivity, specificity, and predictive values along with 95% confidence intervals (CIs) were calculated. RESULTS: The study group comprised 697 patients, including 98 patients with diabetic ketoacidosis (DKA) and 88 with diabetic ketosis (DK). The sensitivity, specificity, positive, and negative predictive values of the urine ketone dip test for the detection of DKA were 99% (95% CI 97% to 100%), 69% (95% CI 66% to 73%), 35% (95% CI 29% to 41%), and 100% (95% CI 99% to 100%), respectively. For DKA and DK, the sensitivity, specificity, positive, and negative predictive values of the urine ketone dip test were 95% (95% CI 90% to 97%), 80% (95% CI 76% to 83%), 63% (95% CI 57% to 69%) and 98% (95% CI 96% to 99%). The anion gap and serum bicarbonate level were less sensitive but more specific than the urine ketone dip test for the detection of DKA and DK. CONCLUSION: The urine ketone dip test has high sensitivity for detecting DKA and a high negative predictive value for excluding DKA in hyperglycemic patients with diabetes with any symptoms of illness. The urine ketone dip test is a better screening test for DKA and DK than the anion gap or serum bicarbonate.

On-line arterial blood gas analysis with optodes: current status.

OBJECTIVES: To summarize the rationale for and the principles of blood gas and pH measurement with photochemical sensors (optodes) placed in the arterial line--either intravascularly (in vivo) or extravascularly (ex vivo). To review the specific problems that occur with in vivo measurement; the clinical data that have been obtained with continuous intravascular and on-demand extravascular systems; and, the role of this technology in the intensive care unit. METHODS AND RESULTS: The principles of absorbance and fluorescent optical sensors are described. The accuracy of intravascular PO2 optodes can be affected by thrombosis, the wall effect (if the sensor touches the arterial wall it may read tissue values) and reduced blood flow past the sensor. Current optical pH, PCO2 and PO2 probe/cannula designs, including hybrid probes with electrochemical PO2 sensors, have not yet fully overcome these problems of the intravascular milieu. On-demand blood gas monitors that locate the optodes extravascularly, within the radial artery line, avoid these intravascular measurement problems. On-demand systems can have accuracy comparable to conventional laboratory blood gas analyzers. With either intravascular or extravascular measurement large patient studies are lacking and the relevant cost benefit ratios are not known. CONCLUSION: Before intravascular monitors can be used routinely for clinical care, reliability, consistency and accuracy will have to be demonstrated in large and widely divergent patient groups. Extravascular on-demand blood gas analysis is accurate, allows trend monitoring of blood gases and decreases the risk of infection, the therapeutic decision time and patient blood loss. As large patient studies are lacking the clinical role of on-line blood gas analysis cannot be clearly delineated.