[Suitability of intraoperative autotransfusion]. / Suivi des techniques de récupération de sang en peropératoire.

This work presents the procedure applied by our hospital to assess the quality and security of intra operative autotransfusion. The suitability of the three following variables has to be constantly assessed: performance of the machines to concentrate and wash collected blood, bacterial contamination of processed blood and rate of adverse events. We note that the procedure is applied with participation of medical and nursing staff. Since its setting-up, we note an amelioration of suitable variables.

[Biomarkers for toxicity and metabolic abnormalities of the main severe poisonings. Clinical and toxicologic symptoms. Conservative determination]. / Biomarqueurs de toxicité et anomalies métaboliques dans les principales intoxications graves. Symptomatologie clinique et toxique. Le prélèvement conservatoire.

The members of the joint group "Toxicology and Clinical Biology" of the French Society of Clinical Biology (SFBC), the French Society of Analytical Toxicology (SFTA), and the Society of Clinical Toxicology (STC), suggest guidelines to meet the requirements of clinical biologists who are not specialized in toxicology. Based on good laboratory practice they propose a number of guidelines. Three synthetic tables have been established. They are not only toxicity biomarkers and metabolic disorders associated with the main severe intoxications, but also clinical signs that are observed during these intoxications, finally biological sampling as a precautionary measure. The table also takes into account approximately fifty xenobiotics: main clinical signs emergency, identification or quantification of the suspected product, useful biological markers, therapeutic, quantitations necessary to take into consideration patient care, and poison antidotes, are described. Recommendations regarding medical and forensic techniques are also proposed by the group. It is also necessary to collect and store biological samples when the individual patients are in charge. These samples will be analyzed or not depending on the individual case history.

[Evaluation of portable point of care instrument: the i-Stat . Report of 7,000 analyses]. / Evaluation d'un analyseur de sant portable: l'i-STAT. Bilan de 7000 analyses.

To validate the use of the i-STAT portable point-of-care instrument, performance checks have been conducted to verify its accuracy for PCO2/PO2 (tonometry) and precision for pH/PCO2/PO2 (control solutions). Results obtained with the i-STAT (pH/PCO2/PO2/Hct) were also compared to those provided by the Bayer Rapidlab 865 routinely used in our laboratory. All these measurements have been conducted under the same conditions using three types of i-STAT cartridges (G3, EG6, EG7) with two of different life duration to each cartridge with a view to observing their potential variability between types and any effect that ageing may have on analytical performances. Differences observed in this respect are not clear enough to draw firm conclusions. On the other hand, we consider the level of PCO2 and particularly PO2 performances not sufficient to warranty their use in the absence of a very strict quality control coupled with a highly developed clinical sense. No real use can be made of values noted for hematocrit (1998 survey).

[The measurement of end-tidal carbon dioxide (PETCO2) is not a significant parameter to monitor in patients with severe traumatic brain injury]. / La pression télé expiratoire en CO2 n'est pas un paramètre pertinent de surveillance d'un traumatisme crânien grave.

PURPOSE: To evaluate the agreement between end-tidal carbon dioxide (PETCO2) and arterial CO2 (PaCO2) in patients with traumatic brain injury and to document the course of the (PaCO2-PETCO2) gradient over time. METHODS: Twenty one traumatic brain injury patients (Coma Glasgow Scale < or = 8) were included in this prospective observational study over a period of six months. Simultaneous determinations of PaCO2 and PETCO2 (by infrared capnometry) were recorded. Agreement between PaCO2 and PETCO2 was determined by the statistical method described by Bland and Altman. Changes in PETCO2 over time were compared with changes in PaCO2. Factors likely to explain a gradient superior to +/- 4 mmHg were explored. RESULTS: One hundred and eleven data pairs were obtained. The bias was 5.5 mmHg with a precision of 5.1 mmHg and limits of agreement ranged from -4.5 mmHg to 15.5 mmHg. The latter exceeded the predefined limits of agreement established to determine interchangeability between methods (+/- 4 mmHg). PETCO2 and PoCO2 changed in opposite directions in 20% of 90 consecutive measurements. Only the duration of ventilation was found to be significantly associated with a gradient superior to +/- 4 mmHg. CONCLUSIONS: In this selected population of patients with severe traumatic brain injury, measurements of PETCO2 and PaCO2 are not interchangeable. Further the PoCO2-PETCO2 gradient is not stable over time and cannot predict variations of PaCO2. The use of PETCO2 instead of PaCO2 could be deleterious in patients in whom strict control of PaCO2 values is required.

Procalcitonin: a valuable indicator of infection in a medical ICU?

OBJECTIVE: To assess the use of procalcitonin (PCT) for the diagnosis of infection in a medical ICU. DESIGN: Prospective, observational study. PATIENTS: Seventy-seven infected patients and 24 patients with systemic inflammatory response syndrome (SIRS) due to other causes. Seventy-five patients could be classified into sepsis (n = 24), severe sepsis (n = 27) and septic shock (n = 24), and 20 SIRS patients remained free from infection during the study. Plasma PCT and C-reactive protein (CRP) levels were evaluated within 48 h of admission (day 0), at day 2 and day 4. RESULTS: As compared with SIRS, PCT and CRP levels at day 0 were higher in infected patients, regardless of the severity of sepsis (25.2 +/- 54.2 ng/ml vs 4.8 +/- 8.7 ng/ml; 159 +/- 92 mg/l vs 71 +/- 58 mg/l, respectively). At cut-off values of 2 ng/ml (PCT) and 100 mg/l (CRP), sensitivity and specificity were 65% and 70% (PCT), 74% and 74% (CRP). PCT and CRP levels were significantly more elevated in septic shock (38.5 +/- 59.1 ng/ml and 173 +/- 98 mg/l) than in SIRS (3.8 +/- 6.9 ng/ml and 70 +/- 48 mg/l), sepsis (1.3 +/- 2.7 ng/ml and 98 +/- 76 mg/l) and severe sepsis (9.1 +/- 18. 2 ng/ml and 145 +/- 70 mg/l) (all p = 0.005). CRP, but not PCT, levels were more elevated in severe sepsis than in SIRS (p<0.0001). Higher PCT levels in the patients with four dysfunctional organs and higher PCT and CRP levels in nonsurvivors may only reflect the marked inflammatory response to septic shock. CONCLUSION: In this study, PCT and CRP had poor sensitivity and specificity for the diagnosis of infection. PCT did not clearly discriminate SIRS from sepsis or severe sepsis.

Evidence for the need of bedside accuracy of pulse oximetry in an intensive care unit.

OBJECTIVE: To compare pulse oximetry saturation (Spo2 with arterial blood gas saturation (SaO2) obtained during clinical routine to determine the optimal lowest reliable value of SpO2 in ventilator-dependent patients before setting up a nurse-directed protocol of FIO2 titration. DESIGN: Prospective clinical study. SETTING: Surgical intensive care unit in a university hospital. PATIENTS: Thirty-three patients with a pulse oximeter probe in whom arterial blood gas was measured with a radial artery line. INTERVENTIONS: SPO2 was recorded by the nurses and compared with SaO2 obtained by blood gas analysis with a co-oximeter. Two sensors currently used in our surgical intensive care unit and connected to a monitor (HP OmniCare M1165/66A; Hewett Packard, Andover, MA) were tested. In group I, the Durensor DS 100A (Nellcor Puritan Bennett, Pleasanton, CA), a reusable sensor, was used. In group II, the Oxisensor D25L (Nellcor Puritan Bennett), a nonreusable sensor, was used. MEASUREMENTS AND MAIN RESULTS: In group 1, 64 data pairs were obtained. In this group, SaO2 ranged from 87 to 98% and SpO2 ranged from 92 to 100%. The bias was -1.90% and the limits of agreement ranged from -5.56 to 1.76%. In group 11, 47 data pairs were obtained. In this group, SaO2 ranged from 87 to 99% and SpO2 ranged from 92 to 100%. The bias was -2.49% and the limits of agreement ranged from -6.62 to 1.64%. CONCLUSIONS: In the range of SaO2 tested, regardless of the sensor used, SpO2 overestimated SaO2. Large limits of agreement were found. Based on this result, the authors concluded that before defining a nurse-directed protocol of FIO2 titration with SpO2, the material used daily must be evaluated. A minimum threshold SpO2 value of 96% in both groups I and II is more reliable to ensure SaO2 > or = 90%.

Non steady state and steady state PKS Bayesian forecasting and vancomycin pharmacokinetics in ICU adult patients.

The pharmacokinetics of vancomycin was investigated in adult ICU patients after the first administration and at steady state. Then the predictive performance of a two-compartment Bayesian forecasting program was assessed in these patients by using population-based parameters and three non steady state vancomycin concentrations as feedback information. Finally a prospective investigation was carried out to search potential covariates. At steady state, a significant decrease (around 30%) in clearance (CL) was observed, while creatinine clearance (CLcr) was stable and a significant increase (around 30%) in volume of distribution (V(SS)) was observed. A two-fold increase in elimination half-life was found. CL was weakly correlated with CLcr at onset of therapy and at steady state. The Bayesian program tended to overpredict vancomycin peak and trough concentrations. A larger mean prediction error and a poorer precision were observed when population-based parameter estimates were used (no feedback) compared to feedback prediction, but the differences were not significant. Mechanical ventilation and concurrent opioid therapy may be pertinent covariates of vancomycin pharmacokinetics. The current work has shown that vancomycin pharmacokinetics in ICU patients displayed a significant variability and a significant change in both clearance and distribution during the course of therapy. Further investigation is necessary to clarify these findings. Moreover, the use of the Bayesian forecasting PKS program in our patients led to a prediction with low bias but rather poor precision. This outcome highlights the need to implement a population modeling approach, to determine the vancomycin pharmacokinetic parameters and covariates in our ICU patients, and to apply this information to provide more accurate concentration predictions.

French national quality control for pH and blood gases: ten years experience.

A national quality control program for blood gas analysers has been established in France since 1983. Buffer solutions are used at two levels of pH, Po2, Pco2 for testing 950 laboratories using 22 different models. These annual programs inform about the accuracy and the precision of the instruments. They also make the user conscientious to different procedures of quality control. Information is also obtained on the yearly turnover of the types of analysers.

Assessment of recently developed blood gas analysers: a multicentre evaluation.

Providing guidelines for testing expected inaccuracy and imprecision is still a matter under debate. The Expert Panel of the French Society of Clinical Chemistry has developed a protocol, which was based on a comparative multi-centre evaluation of four instruments: the Ciba-Corning 278, the Instrumentation Laboratory 1306, the Nova SP 5 and the ABL 330. The purpose was to evaluate the analytical performance and efficiency of the analysers. Another aim was to design a valid approach for evaluating any new system. As buffered aqueous solutions and fluorocarbon emulsions give only partial information, tonometered blood was used at different levels of gas mixture, even though it is both difficult and time-consuming. Comparisons have been established on patients' blood samples with the analysers currently used in the evaluation sites. The tests showed that the four analysers have the same degree of precision, and interinstrument comparisons demonstrated a very high degree of reliability.This analysis emphasizes that the evaluation of instruments for pH and blood gas analysis is neither easy nor is it often done, mainly due to the choice of a quality-control material and the lability of the measured parameters.

Ca2+ measurement with ion selective electrodes. The French coordinated evaluation of seven analyzers, for a better clinical relevance and acceptance.

The measurement of ionized calcium has evolved in the last decade, and can now be easily performed by clinical laboratories using direct potentiometric analyzers available from a number of manufacturers. An original protocol for a comparison of the analyzers was used through a parallel multicenter evaluation in France. Using newly developed aqueous buffered solutions, this study focused not only on the analytical performance and operational handling of analyzers, but also on possible interferences in biological samples and the clinical relevance of the measurement with respect to the techniques of sample collection. All the instruments exhibited good precision and linearity, and were easy to handle and robust for daily use. However, not all the models gave identical results on the same patient's specimen. The utility of some Ca2+ analyzers has been further enhanced by the ability to "correct" the results to pH 7.40, although care must be taken in the interpretation of these results. While there are a number of clear-cut situations in which Ca2+ measurement is more relevant than total calcium, it seems that chemical activity of Ca2+ in blood may sometimes be considered with great caution under pathological conditions. The role of Ca2+ measurement in routine will be discussed in relation to the potential benefits of the instruments in laboratories.

Comparison of the influence of dihydroergotoxine on cerebral oxygenation in the normoxic and hypercapnic hypoxic dog.

50 bastard dogs are anesthetized by chloralose (100 mg/kg) and mebubarbital (5 mg/kg) and then perfused by three-different dosages of dihydroergotoxine (DHET) (1.25; 2.5; 5 micrograms/kg/min). The effect of DHET on cerebral oxygenation is analyzed under two conditions: normoxia and hypercapnic hypoxia. The following biochemical and physiological parameters are studied: mean vertebral flow (MVF), aortic arterial pressure (AP), heart rate (HR); pO2, pCO2, total CO2, pH, haemoglobin saturation ratio, both in arteries and veins. Other parameters are calculated: O2 arterio-venous difference, CMRO2, O2 extraction coefficient, cerebral O2 supply, vertebral resistance. Under normoxia, DHET, whatever the dosage, induces a decrease of the MVF associated with an inconstant decrease of oxygen supply. At 2.5 micrograms/kg/min, a permanent and significant increase of CMRO2 is obtained. At 5 micrograms/kg/min, similar results are obtained although the decrease of HR and AP is more pronounced. Under hypoxia, the arterio-venous oxygen content difference and the CMRO2 are increased by DHET (2.5 micrograms/kg/min) without any repercussions on AP and MVF (hypothetical role of the blood pH decrease). In conclusion, DHET doubles the CMRO2, as a consequence of an increase of the oxygen extraction ratio. A 2.5 micrograms/kg/min dosage is by itself able to give this maximum effect without any major consequences on HR, AP and MVF. This effect is still obtained in hypoxia without any peripheral vascular effect.

[Advantages and constraints of recent multichannel selective analyzers]. / Avantages et contraintes des analyseurs sélectifs multiparamétriques récents.

The analyzers have been defined as follows: the analyzers are multiparametric (at least 5 parameters available simultaneously), selective, operating patient by patient, list price on May 1, 1984 below 1,000,000 francs, and distributed in France after January 1, 1981. This definition applies in particular to systems already widely used in French Laboratories, such as the Technicon RA 1000, and the Hitachi Boehringer 705. It also applies to systems distributed more recently, such as the Kone "Progress" and the Coultronics "Dacos". Based on data provided by the manufacturers (technical instructions, operating instructions, evaluation reports, etc) and data provided by a certain number of users, we have tried to appraise the advantages and constraints of these analyzers with respect to the following points: required environment (installation, electrical current, temperature), training of personnel, ease of adaptation, work organization, rhythms, operating cost, ease of use, verification of correct function, format of results, maintenance, etc. Lastly, we discuss the problem of the reliability of the results (precision, accuracy), in particular the problems of referencing in substrate assays, and the problems of accuracy in the measurement of enzymatic activities, considering the current norms of standardization.

[Aspirin and gastroduodenal toxicity. A double-blind endoscopic study of the effects of placebo, aspirin and lysine acetylsalicylate in healthy subjects]. / Aspirine et toxicité gastroduodénale. Etude endoscopique en double insu des effets d'un placebo, de l'aspirine et de l'acétylsalicylate de lysine chez le sujet sain.

The aim of this double-blind endoscopic study was to compare the effects of placebo (group I, 5 patients), lysine acetylsalicylate (group II, 7 patients) and acetylsalicylic acid (group III, 7 patients) on the gastric and duodenal mucosa in healthy humans. Endoscopy was performed before and one hour after endoscopic instillation of aspirin (500 mg) or placebo in the stomach. Endoscopy was repeated after one week of aspirin-treatment (2 g per day) or placebo. Endoscopic findings were graded from 0 to 6 with regard to the aspect of the lesions (petechiae, erosions, ulcers) and to their number (less than 10; greater than 10). One hour after placebo instillation endoscopic findings were normal in all the patients of group I. Three and 5 patients of groups II and III, respectively, developed gastric lesions but none had duodenal lesions. At day 8 only one subject from group I had gastric petechiae. After one week of aspirin-treatment, 13 out of the 14 subjects of groups II and III developed gastric lesions and 3 in each group had duodenal lesions. The endoscopic score was significantly higher in group III than in group II for the following localisations: fundus, antrum, entire stomach, and stomach + duodenum. However the duodenal score was not significantly different between these 2 groups. It is concluded that, after a one-week treatment in normal patients, standard aspirin produces 2 fold more gastric mucosal damage than does soluble aspirin.

[Determination of reference values of plasma oncotic pressure by the Wescor Cop Oncometer]. / Détermination des valeurs de référence de pression oncotique plasmatique par le "Wescor Cop Oncometer".

The authors studied the standard values for plasma oncotic pressure in 216 blood donors. They compared the oncotic pressure in terms of sex and whether a serum or plasma sample was used. They also studied the stability of the oncotic pressure over a 24 hour period.