Fault detection in a real-time monitoring network for water quality in the lagoon of Venice (Italy).

In the context of monitoring water quality in natural ecosystems in real time, on-line data quality control is a very important issue for effective system surveillance and for optimizing maintenance of the monitoring network. This paper presents some applications of recursive state-parameter estimation algorithms to real-time detection of signal drift in high-frequency observations. Two continuous-discrete recursive estimation schemes, namely the Extended Kalman Filter and the Recursive Prediction Error algorithm, were applied to assuring the quality of the dissolved oxygen (DO) time series, as obtained from the Lagoon of Venice (Italy) during August 2002, through the real-time monitoring network of the Magistrato alle Acque (the Venice Water Authority). Results demonstrate the effectiveness of the methodology in early detection of a probable drift in the DO signal. Comparison of these results with those obtained from the application of a related recursive scheme (a Dynamic Linear Regression procedure) suggests the strong benefits of approaching the problem of on-line data quality control with several (not merely a single) independent such estimation methods.

[Controlled analgesia in a burn patient: fentanyl sparing effect of clonidine]. / Analgésie contrôlée par le patient brûlé: effet d'épargne de fentanyl par la clonidine.

OBJECTIVE: To determine the sparing effect of clonidine (C) on fentanyl (F) demand in burned patients under PCA. STUDY DESIGN: Prospective, randomized, double blind study versus placebo. PATIENTS: Twelve consecutive patients with mean burn surface area of 20 +/- 9%, studied between the third and the eighth day post-burn. METHODS: F was delivered by a PCA pump (bolus: 1 mg.kg-1). In the morning, burn patients received additional F (5 mg.kg-1) before hydrotherapy. After randomisation, C or placebo (P) were alternatively infused over 24 hours. Demands for F during the morning, the afternoon and the evening were noted. Pain scores were measured on a visual analogic scale. In eight patients, plasma levels of F (pF) were iteratively measured. Heart rate, arterial pressure, respiratory rate and SpO2 were monitored. RESULTS: Analgesic demands were 19.5/day under P and 9.5 under C (P < 0.0001). Pain reoccurred for pF of 4.1 under C vs 5.7 under P (P < 0.05) with same pain scores in the two groups. After a pain stimulus, pain scores were lower under F, despite lower pF (P < 0.05). Arterial pressure and heart rate were significantly lowered during the first hour of C infusion. CONCLUSION: Doses of F and pF required to reach analgesia were very high. Adding C decreases by 50% the F demand and lowers pF. Minor haemodynamic effects were observed during the first hour of C infusion.

A reference standard for plasma proteins is required for nutritional assessment of adult burn patients.

Plasma levels of visceral proteins (VP) are commonly used for evaluation of nutritional status. Low values observed in burn patients are caused by several factors including microvascular hyper-permeability and inflammatory processes. The aim of the study was to define a range of standard values specific to burn patients. Retrospective review: from days post-burn 12 to 43, four VP and three acute phase reactants (APR) were measured twice a week, in the plasma of 107 burn patients. From these data, standard' values were determined in respect with burn surface area (BSA) and post-burn time. The results were that the VP increase and APR decrease linearly during the study. Correlation between plasma proteins and BSA or post-burn day, change from protein to protein. Albumin and transferrin are less sensitive than prealbumin and especially retinol binding protein to variations of APR, but transferrin lacks of specificity. The conclusion of the study was that plasma levels of VP have to be compared to reference standard values. When levels lower than theoretical values are observed, simultaneous APR values (especially C reactive protein) have to be compared to their own reference standard, in order to separate nutritional from inflammatory effects.

[Metabolism of albumin]. / Métabolisme de l'albumine.

Albumin is quantitatively the most important plasma protein. Albumin is a major factor for the maintenance of intravascular oncotic pressure; it also plays a significant role in the transport of exogenous or endogenous substances. Serum albumin is synthesized at a high rate in the liver. This synthetic process is modified by many interrelated factors. Oncotic pressure, malnutrition, toxins and trauma may reduce albumin production or secretion. Hormones regulate synthesis and degradation. Albumin is widely distributed, however the concentration in the extravascular space is low, compared to that in the plasma or lymph. While considerable data are available concerning albumin synthesis, little is known about degradation and further studies are required.

[Resistance to vecuronium in burnt patients. Influence of the burnt surface on the effectiveness of the dose 95]. / Résistance au vécuronium chez le brûlé. Influence de la surface brûlée sur la dose efficace 95.

OBJECTIVE: To assess the neuromuscular blocking effect of vecuronium in adult burn patients, to draw dose-response curves, to determine the ED 95 according to burn surface area, to analyze the time course of this pattern in order to recognize the development of a resistance according to the length of postinjury period. STUDY DESIGN: Prospective open study, extending over a 12 month period. PATIENTS: Sixty-three consecutive adult burn patients in an acute phase and 13 control patients who had been thermally injured at least 500 days before their inclusion in the study. METHODS: Anaesthesia was achieved with thiopentone, fentanyl and vecuronium in patients undergoing excision and autograft surgery. Neuromuscular blockade was assessed by thumb adduction, measured by electromyography using evoked train of four responses to ulnar nerve stimulation. Dose-response curves were determined using the single dose method from only one predetermined dose of vecuronium per patient on each day of the study. Dose-response curves were compared using linear regression and ED 95 were calculated from log-probit data. RESULTS: In the control group, ED 95 was 53 mg.kg-1. Before the 7th postinjury day, patients did not differ from controls. Between the 7th and the 70th postinjury day the ED 95 increased significantly. Patients with a burn surface area (BSA) of less than 20% had a ED 95 of 69 mg.kg-1, between 20% and 40% of BSA the ED 95 was 103 mg.kg-1, between 40% and 60% BSA the ED 95 was 134 mg.kg-1 and patients with a BSA over 60% had a ED 95 at 154 mg.kg-1. The onset of action increased in all groups and was significantly different from control group. CONCLUSION: Acutely burn patients become resistant to the neuromuscular blocking effect of vecuronium. This resistance is related to the magnitude of burn injury. The mechanism of resistance is related to an increase in nicotonic acetylcholine receptors. In these patients, the dose of vecuronium must be titrated to achieve effective muscular paralysis: the correcting factor is 1.3 for a BSA under 20%, 1.9 for a BSA between 20 and 40%, 2.5 for a BSA between 40 and 60%, and 2.9 for a BSA above 60%.

[Saccharomyces boulardii fungemia in a patient with severe burns]. / Fongémie à Saccharomyces boulardii chez un brûlé grave.

A case of Saccharomyces boulardii fungaemia in a burn patient is reported. S. boulardii was administered in order to improve the digestive tolerance to enteral nutrition. After a surgical procedure, a sepsis syndrome occurred, with a white blood cell count increase, abdominal meteorism and respiratory insufficiency, associated with seven blood cultures positive to S. boulardii. Digestive translocation of the yeast seems to be the most likely origin of this fungaemia. Some fungaemias from S. boulardii have been published. However it is not usual to find such severe clinical features as in our case which leads us to reconsider the therapeutic use of S. boulardii in situations including a gastrointestinal tract suffering.

[Peculiarities of the emergency care in pregnant women]. / Particularités de la prise en charge des urgences chez la femme enceinte.

Awareness of the physiological changes associated with pregnancy is essential for the management of patients during pregnancy. Cardiovascular status is characterised by hypervolemia and cardiac hyper-output with low resistance. Increased oxygen consumption and respiratory work result in an increased risk of hypoxia. Fetal well-being must also be taken into account. During cardiorespiratory arrest, aortocaval compression by the pregnant uterus may impair the efficacy of CPR and uterine displacement is a routine measure starting from 20 weeks after the LMP. The same factors are involved in hemorrhagic shock, justifying uterine displacement and the ensuring of optimal oxygen transport and utilisation.

Diet-induced thermogenesis in HIV infection.

OBJECTIVE: To assess whether postprandial dietary thermogenesis contributes to weight loss during HIV infection. METHODS: The thermogenic response to a test meal (15 kcal/kg) was evaluated with indirect calorimetry in 16 HIV-infected patients in a stable condition and compared with a control group. Patients were compared according to AIDS (n = 8) or non-AIDS (n = 8) status and to body weight loss (WL; n = 9) or no loss (NL; n = 7). Indirect calorimetry was performed after fasting 6 h and during 5 h after the test meal. RESULTS: Maximum value of energy expenditure was reached later in the WL group than in the control and NL group (200 versus 30 min, respectively). Energy expenditure returned to the initial value 300 min after the test meal (last measurement) in the control group but remained elevated in the patient group. Energy expenditure after food intake was more elevated in HIV-infected patients than in controls, especially in patients with detectable clinical change in their nutritional status (0.96 versus 0.72 kcal/kg body weight). CONCLUSION: Both kinetics and quantitative aspect of dietary thermogenesis are modified during HIV infection and the different variations are dependent on the extent of body weight loss.

[Patient-controlled analgesia: a study of fentanyl requirements in burnt patients during the acute phase]. / Analgésie contrôlée par le patient: étude de la demande en fentanyl chez le brûlé à la phase aiguë.

This study assessed over the first post-burn week the patients' demands for opiates delivered with a PCA device, changes in opioid delivery along the day, especially during painful events and the incidence of side effects. Twenty-two patients (8 women, 14 men), mean age 33 years (+/- 12 SD), mean BSA 21% (+/- 13 SD), mean deep dermal burn 12% (+/- 11 SD) were included. Fentanyl was delivered by i.v. route using a PCA device during the first 6 days post burn. Bolus dose was fixed at 1 microgram.kg-1, lock-out time at 30 min and the 4 h limit dose at 7 micrograms.kg-1. The following data were collected every day: satisfied and non-satisfied demands, total daily dose, demands during and after dressing change period (4 h), during afternoon (10 h) and overnight periods (10 h). Heart rate (HR), respiratory rate (RR), blood pressure (BP), Paco2 and Spo2 were also monitored. The mean total daily demands were similar from D1 to D6 (28 +/- 7). Around 7 demands/day were not satisfied. The mean total daily satisfied demands were also the same: 21 +/- 5. Individual demands were over a wide range (minimum: 15, maximum: 41 demands/day for total demands and 13 and 34 respectively for the satisfied ones). Mean fentanyl delivery was 1.7 +/- 0.1 microgram.kg-1.h-1 during dressing period, 0.9 +/- 0.3 microgram.kg-1.h-1 during afternoon period (10 h) and 0.5 +/- 0.2 during overnight period (10 h). No-satisfied demands were around 4 boluses during dressing change period, 2 boluses during afternoon period, and one bolus during overnight period.(ABSTRACT TRUNCATED AT 250 WORDS)

[Methods for isotopic exploration of protein metabolism. Effects of anesthetics and surgical stress]. / Méthodes d'exploration isotopique du métabolisme protéique. Effets des agents anesthésiques et du stress chirurgical.

Techniques using stable isotopes, the only ones authorized in France, allow a new insight into protein metabolism. These methods use an amino acid labelled with nitrogen 15, carbon 13 or deuterium, making it possible to measure the synthesis and overall breakdown of the body, as well as the speed of tissue synthesis and specific protein synthesis. Analytically, the techniques using nitrogen 15 are based on measurements of the enrichment in terminal urinary products: total nitrogen, urea or ammonia. Methods using carbon 13 have become preferred, even though they are more invasive, as they require sampling of blood and expired air. In hypercatabolic states, particularly in intensive care, reaching a steady state while measuring the flux of an amino acid entails the use of a short perfusion preceded by priming, to reduce the risk of recycling. The flooding dose method, consisting of the simultaneous injection of a labelled amino acid and a large quantity of unlabelled amino acid, seems to be of particular interest for measuring specific protein synthesis. Whole body breakdown is easily calculated from flux of labelled amino acid. The combination of isotopic infusion with the net forearm balance for amino acid allows to measure changes in muscle protein synthesis and breakdown. In contrast, measurement of breakdown is more difficult. For example, fractional breakdown rate and tissue sites of catabolism of plasma protein cannot be determined in humans. These isotopic techniques have contributed to improving our understanding of protein metabolism as far as synthetic and catabolic processes are concerned. The effect of food intake on protein turnover is different in muscle and liver. The immediate responses of food intake is an increase of muscular protein synthesis with a decrease of it's breakdown, while liver protein synthesis does not change. In contrast, liver breakdown increases during post absorptive state. Insulin plays a major role in regulation of protein synthesis and inhibits proteolysis. Surgical stress is characterized by an increase of whole body protein synthesis and breakdown and a net protein catabolism. Uncomplicated surgery, but not general anaesthesia, induces change in protein turnover. The protein synthesis rate is unaffected by general anaesthesia while a decrease is seen after surgery. The effect of anaesthetic agents is not well characterized. In rats, lung protein synthesis is reduced by halothane, pentobarbitone and midazolam combined with fentanyl while liver protein synthesis is depressed by all these agents, excepted by midazolam/fentanyl. The effects of anaesthetic agents on skeletal muscle and heart are minor.

[Nutrition proteins and muscular catabolism in severely burnt patients. Comparative effects of small peptides or free amino acids]. / Protéines nutritionnelles et catabolisme musculaire chez le brûlé grave. Effets comparatifs de petits peptides ou d'acides aminés libres.

The beneficial effects of high caloric and protein enteral diet on wound healing and prevention of infection in severely burned patients is well documented. However, the relative proportion of each nutrient and especially the form of nitrogen supply have not yet been clearly established. The aim of this study was to compare, in severely burned patients, the efficiency of a partial protein hydrolysate and free amino acid formula during a 15-day enteral feeding. Twenty burned patients ranging in age from 18 to 67 years with a mean burn size of 40 +/- 12% of total body surface area, of which 31 +/- 14% was deep dermal, were studied prospectively and randomised in two groups. Group A received the free amino acid diet which was obtained by hydrolysis of the protein hydrolysate given to Group B (60% small peptides). All diets contained a nitrogen source of similar amino acid composition. Nitrogen balance was measured daily and serum protein concentrations were determined on days 0, 4, 8, 11 and 15. Anthropometric parameters, urinary 3 methylhistidine/creatinine ratio and plasma amino acid concentration were assessed on days 0, 8 and 15. Daily and cumulative nitrogen balance at D15 did not differ between the two groups. In group A, the circulating visceral proteins increased at all times of the study without decrease of acute phase reactant, whereas only transthyretin and retinol binding protein increased at D11 and D15 with a significant decrease of C-reactive protein at the same time in the other group.(ABSTRACT TRUNCATED AT 250 WORDS)

[Curare and burns]. / Curares et brûlure.

Burns of more than 15% of the body surface area result in major physiological changes with an alteration of cardiovascular, pulmonary, hepatic and renal functions, as well as modifications in the pharmacokinetics and the pharmacodynamics of many drugs. Among these, a major change in the activity of muscle relaxants occurs which can be specific to this pathology. Succinylcholine is contra-indicated during recovery from a burn trauma because of a possible hyperkaliemic response, directly related to the dose, the post-burn delay and the area of burned body surface. The kaliemic response and the related cardiac complications remain unpredictable. The height of twich depression with small doses of succinylcholine such as 0.1 to 0.2 mg.kg-1, demonstrates the hypersensitivity to this agent and does cause neither metabolic disturbances nor cardiac arrest. Nevertheless, the administration of succinylcholine is contra-indicated for from the 5th day on at least two years after the burn injury. Conversely, the action of non-depolarizing muscle relaxants is characterized by a resistance, which is correlated to both the post-traumatic delay and the extent of the burned area. It starts on about the seventh day, reaches peak intensity between day 15 and day 40 and can persist up two years after the thermal injury. In the course of a burn, the so-called "immature" acetylcholine receptors, characterized by the substitution of the sub-unit epsilon by a protein gamma, increase at the level of the end plate areas and the extra-synaptic muscle membrane. These receptors explain both the hyperkaliemic response and the hypersensitivity to succinlycholine.(ABSTRACT TRUNCATED AT 250 WORDS)

[Biological changes in intra-uterine resections under glycine irrigation]. / Perturbations biologiques au cours des résections intra-utérines sous irrigation de glycocolle.

This study was carried out to assess the relations between plasma glycine concentrations and the biochemical changes occurring during intra-uterine resections (IUR) under glycine irrigation. Sixty patients with benign uterine conditions were included. They were all ranked ASA 1 or 2. The biological parameters were assessed before surgery (T0), at the end of surgery (T1) and 60 min afterwards (T2). They included the blood count and blood concentrations of sodium, potassium, chloride, proteins, bicarbonates, glucose, urea nitrogen, creatinine and glycine. Plasma osmolarity was calculated. The irrigation of the uterine cavity resulted in an increase of glycine concentrations (28% of cases), and a decrease of sodium (22% of cases), proteins and haematocrit (32% of cases). Mean osmolarity remained unchanged. Blood glycine concentrations were directly correlated with the volume of irrigating solution, as well as with the duration of surgery. Protidaemia was inversely related to the blood glycine concentration. Multiparous patients had lower glycine concentrations than nulliparous patients. This was probably due to the uterine cavity being less compliant in the latter. On the other hand, there was no correlation with the uterine pathological condition. In this series, five cases of uterine perforation occurred with very large biological variations, especially a decrease in haematocrit and osmolarity. In these cases a clinical and biological water intoxication syndrome may occur as a result of large volumes of irrigating fluid passing into the peritoneal cavity.

Monitoring of central venous oxygen saturation versus mixed venous oxygen saturation in critically ill patients.

Continuous monitoring of mixed venous (SvO2) and central venous (ScO2) oxygen saturation was compared in 7 critically-ill patients (Apache II score: 19 +/- 2.1) to determine whether or not information derived from ScO2 were reliable in clinical practice. Patients were catheterized with both a pulmonary artery (PA) and a central venous (CV) catheter, each of them mounted with fiberoptic sensors (Opticath PA Catheter P7110 and Opticath CV Catheter U440, Abbott). A total of 580 comparative measurements were obtained during periods without and with therapeutic interventions (drug-titration, bronchial suction, use of PEEP, changes in FiO2 ...). The systematic error between the 2 measurement techniques was 0.6% and 0.3% in periods with and without therapeutic interventions, respectively. The variability between the 2 techniques was 10% for both periods. Differences between the values were greater than or equal to 5% in 49% of values during periods of stability and in 50% of values during periods with therapeutic interventions. There were poor correlations between the values during periods without (r = 0.48) and with therapeutic interventions (r = 0.62). Better, but still less than ideal, correlations were obtained with changes in SvO2 and ScO2 during periods without (r = 0.70) and with therapeutic interventions (r = 0.77). Although there is a need to develop a simple technique to monitor mixed venous oxygen saturation, the present study indicates that ScO2 monitoring was not reliable in the study patients.