Preoperative fasting does not affect haemodynamic status: a prospective, non-inferiority, echocardiography study.

BACKGROUND: The link between preoperative fasting and hypovolaemia remains unclear. We tested the hypothesis that preoperative fasting does not significantly increase the proportion of patients with hypovolaemia according to transthoracic echocardiography (TTE) criteria. METHODS: Patients of ASA status I-III and without bowel preparation were included in a non-inferiority, prospective, single-centre trial. Patients underwent passive leg raising (PLR) test and TTE at admission (Day 0) and after 8 h fasting (Day 1). The primary hypothesis was that an 8 h preoperative fasting does not increase the proportion (margin=5%) of patients with a positive PLR test ('functional approach'). The secondary hypothesis was that echocardiographic filling pressures or stroke volume (margin 10%) are not affected by preoperative fasting ('static approach'). RESULTS: One hundred patients were included and 98 analysed. After an 8 h fasting, the change in the proportion of responders to PLR was -6.1% [95% confidence interval (CI)=-16.0 to 3.8] of responders to PLR test on Day 0 when compared with Day 1. Because 95% CI was strictly inferior to 5%, there was no significant increase in the proportion of PLR responders on Day 1 when compared with Day 0. The 95% CI changes of static variables were always fewer than 10%, meaning that preoperative fasting induced significantly no relevant changes in static variables. CONCLUSION: Preoperative fasting did not alter TTE dynamic and static preload indices in ASA I-III adult patients. These results suggest that preoperative fasting does not induce significant hypovolaemia. Clinical trial registration NCT 01258361.

Does the type of fluid affect rapidity of shock reversal in an anaesthetized-piglet model of near-fatal controlled haemorrhage? A randomized study.

BACKGROUND: The optimal resuscitation fluid for the early treatment of severe bleeding patients remains highly debated. The objective of this experimental study was to compare the rapidity of shock reversal with lactated Ringer (LR) or hydroxyethyl starch (HES) 130/0.4 at the early phase of controlled haemorrhagic shock. To assess the influence of vascular permeability in this model, we measured plasma vascular endothelial growth factor (VEGF) levels during the experiment. METHODS: Thirty-six anaesthetized and mechanically ventilated piglets were bled (<30 ml kg(-1)) to hold mean arterial pressure (MAP) at 40 mm Hg for more than 30 min and were resuscitated in two randomized groups: LR (n=14) or HES (n=14) at 1 ml kg(-1) min(-1) until MAP reached its baseline value of ±10%. MAP was maintained at its baseline value for 1 h. The time and fluid volume necessary to restore the baseline MAP value were measured. RESULTS: The time to restore the baseline MAP value of ±10% was significantly lower in the HES group (P<0.001). During the initial resuscitation phase, the infused volume was 279 (119) ml in the HES group and 1011 (561) ml in the LR group (P<0.0001). During the stabilization phase, the infused volume was 119 (124) ml in the HES group and 541 (506) ml in the LR group. Biological data and plasma VEGF levels were similar between the groups. CONCLUSIONS: Restoration of MAP was four times faster with HES than with LR in the early phase of controlled haemorrhagic shock. However, there was no evidence of increased vascular permeability.

Changes in the availability of bedside ultrasound practice in emergency rooms and prehospital settings in France.

OBJECTIVE: Ensuring the availability of ultrasound devices is the initial step in implementing clinical ultrasound (CUS) in emergency services. In France in 2011, 52% of emergency departments (EDs) and only 9% of mobile intensive care stations (MICS) were equipped with ultrasound devices. The main goal of this study was to determine the movement of these rates since 2011. METHODS: We conducted a cross-sectional, descriptive, multicentre study in the form of a questionnaire. To estimate the numbers of EDs and MICS equipped with at least one ultrasound system with a confidence level of 95% and margin of error of 5%, 170 responding EDs and 145 MICS were required. Each service was solicited three times by secure online questionnaire and then by phone. RESULTS: Three hundred and twenty-eight (84%) services responded to the questionnaire: 179 (86%) EDs and 149 (82%) MICS. At least one ultrasound machine was available in 127 (71%, 95% CI [64; 78]) EDs vs. 52% in 2011 (P<0.01). 42 (28%, 95% CI [21; 35]) MICS were equipped vs. 9% in 2011 (P<0.01). In 97 (76%) EDs and 24 (55%) MICS, less than a half of physicians were trained. CUS was used at least three times a day in 52 (41%) EDs and in 8 (19%) MICS. CONCLUSION: Our study demonstrates improved access to ultrasound devices in French EDs and MICS. Almost three-quarters of EDs and nearly one-third of MICS are now equipped with at least one ultrasound device. However, the rate of physicians trained per service remains insufficient.

[General practitioners' and intensivists' relationships: intensivists' point of view from eight French southern regional areas]. / Relations entre médecin traitant et médecin réanimateur: l'opinion des réanimateurs de huit départements du sud de la France.

OBJECTIVES: Assessment of relationship between general practitioners and intensivists. STUDY DESIGN: Intensivists were questioned by phone from June 14th to September 28th 2004. METHODS: 245 out of 264 intensivists from 8 French Southern regional areas were questioned concerning their relationship with critically ill patients' general practitioner. RESULTS: Patients were mainly admitted into Intensive care Unit (ICU) from the Emergency Department (55%). An information letter from the general practitioner was reported for 20% of admitted patients but 50% of these letters was assumed as not informative. The informations concerning the patient's medical history, therapies, and disease leading to admission and the patient's status were assessed with 6.5, 7.0, 6.0 and 2.0, respectively (maximal note=10). The intensivists contacted the general practitioner for 30% of admitted patients. During the stay in ICU, 33% general practitioners were reported to request informations by phone or visit in ICU. When the stay in ICU was>10 days, the general practitioner was nearly never regularly informed about patient's status. When the patient was discharged from the ICU, 80% of intensivists used an exhaustive typed report to inform the general practitioner. The overall relationship between the general practitioner and the intensivist was assessed as 5.5/10. Insufficient information in the general practitioner's letter at admission, the lack of request for information during the stay in ICU, the lack of contact with the general practitioner by the intensivist and an intensivist's age between 46 and 55 were associated with a relationship assessment<4/10).

MACVIA-LR (Fighting Chronic Diseases for Active and Healthy Ageing in Languedoc-Roussillon): A Success Story of the European Innovation Partnership on Active and Healthy Ageing.

The Région Languedoc Roussillon is the umbrella organisation for an interconnected and integrated project on active and healthy ageing (AHA). It covers the 3 pillars of the European Innovation Partnership on Active and Healthy Ageing (EIP on AHA): (A) Prevention and health promotion, (B) Care and cure, (C) and (D) Active and independent living of elderly people. All sub-activities (poly-pharmacy, falls prevention initiative, prevention of frailty, chronic respiratory diseases, chronic diseases with multimorbidities, chronic infectious diseases, active and independent living and disability) have been included in MACVIA-LR which has a strong political commitment and involves all stakeholders (public, private, patients, policy makers) including CARSAT-LR and the Eurobiomed cluster. It is a Reference Site of the EIP on AHA. The framework of MACVIA-LR has the vision that the prevention and management of chronic diseases is essential for the promotion of AHA and for the reduction of handicap. The main objectives of MACVIA-LR are: (i) to develop innovative solutions for a network of Living labs in order to reduce avoidable hospitalisations and loss of autonomy while improving quality of life, (ii) to disseminate the innovation. The three years of MACVIA-LR activities are reported in this paper.

Multiple-dose pharmacokinetics of pefloxacin in patients with hepatocellular deficiency.

Multiple-dose pharmacokinetics of pefloxacin were evaluated in 25 patients with hepatocellular insufficiency. The severity of liver disease was graded A, B or C according to the Child-Pugh classification. Pharmacokinetic parameters evaluated in patients on day 1 of treatment were compared with those computed in 11 healthy volunteers (the control group) after a single dose. Blood samples were taken at frequent intervals after drug administration and assayed by high performance liquid chromatography. The mean age of patients with liver impairment was slightly greater (59.5 years, range 33 to 81 years) than that of the control group (46.7 years, range 42 to 51 years). In the patients with liver disease, the mean (+/- SD) half-life of elimination, although highly variable, was significantly longer (46.3 +/- 42.5 hours) than in the control group (11.3 +/- 3.5 hours, p < 0.001). The total clearance was significantly decreased (1.76 +/- 1.31 L/h vs 6.03 +/- 2.99 L/h in the control group). In groups B and C of the Child-Pugh classification, total body clearance was about 30% of normal values. Elimination half-life increased by 200% in group B and 373% in group C compared with values in healthy volunteers. Intergroup differences (group B vs group C of the Child-Pugh classification) were not statistically significant. The minimum concentrations inhibiting 90% of Gram-negative strains (MIC90) were exceeded by plasma pefloxacin concentrations throughout treatment. For most patients, trough plasma concentrations were above 2 mg/L and peak plasma concentrations averaged 8.5 mg/L. Large inter- and intraindividual variations in the elimination half-life, total clearance and volume of distribution were observed.(ABSTRACT TRUNCATED AT 250 WORDS)

Clinical pharmacokinetics during continuous haemofiltration.

Continuous haemofiltration is an extracorporeal technique that is increasingly used to remove fluid, electrolytes, and other waste products from the blood supply of critically ill patients with acute renal failure. Continuous arteriovenous haemofiltration (CAVH), where the blood exits the body from an artery and re-enters through a vein, is widely used. Continuous venovenous haemofiltration (CVVH), where blood both exits and enters through a vein by way of a mechanical pump, avoids problems that result from the variable ultrafiltration rate found during CAVH. Continuous arteriovenous or venovenous haemodiafiltration (CAVHD or CVVHD) combine continuous haemofiltration and haemodialysis. All methods involve ultrafiltration of the patient's blood through a filter that is highly permeable to water and small molecules. Drug elimination by haemofiltration depends mainly on the rate of ultrafiltration, the drug protein binding and the sieving coefficient of the membrane. Because patients undergoing continuous haemofiltration have impaired renal function, dosage reduction is often recommended so that adverse drug reactions are avoided. In contrast, if drug removal by haemofiltration is significant, dosage supplementation may be required to ensure therapeutic efficacy of the drug. Therefore, knowledge of the impact of continuous haemofiltration on drug elimination and the pharmacokinetic profile of drugs is essential to good clinical management. The currently available information on the clinical pharmacokinetic aspects of drug therapy during continuous haemofiltration are summarised. Drugs commonly associated with haemofiltration therapy are tabulated with updated pharmacokinetics and drug-monitoring information.

Interactions between hemodynamic and hormonal modifications during PEEP-induced antidiuresis and antinatriuresis.

The interactions between hemodynamic and hormonal modifications during antidiuresis and antinatriuresis induced by positive end-expiratory pressure (PEEP) were studied in six patients under 15 cm H2O PEEP before PEEP and after the addition of lower body positive pressure (LBPP) to PEEP (PEEP+LBPP). We measured or calculated the following: cardiac index, systemic arterial, right atrial, pulmonary arterial, and pulmonary artery occlusive pressures; indexed renal blood flow (iodohippurate 131 sodium clearance); total blood volume (chromium 51 radiolabeled RBCs); glomerular filtration rate; urinary output; fractional excretion of sodium (FE Na+); plasma concentrations of antidiuretic hormone (ADH), plasma renin activity (PRA), norepinephrine and epinephrine; urinary concentration of PGE2 (PGE2u). Although LBPP application corrected PEEP deleterious effects on systemic and renal hemodynamics, sustained fall in Vu and in FE Na+ were observed. Antidiuresis was not due to ADH release. Sympathetic activation and high PRA appeared the main determinants of renal function alterations in PEEP ventilation.

CO assessment by suprasternal Doppler in critically ill patients: comparison with thermodilution.

OBJECTIVE: Comparison of suprasternal Doppler (SST) and thermodilution (TD) for the measurement of cardiac output (CO) in critically ill patients. DESIGN: Prospective study. SETTING: Intensive care unit of a university hospital. PATIENTS AND PARTICIPANTS: 65 consecutive critically ill patients requiring a pulmonary artery catheter. INTERVENTIONS: Paired CO measurements were made simultaneously using SST and TD by two independent operators. The time to obtain a CO value by SST was measured. Correlation coefficients and the linear regression equation were determined. A Bland and Altman diagram was plotted. A Bland and Altman diagram was also plotted for the level of cardiac index (CI) values (low: CI < 2.5 l min(-1) m(-2); normal: 2.5 < or = CI < or = 4.5 l min(-1) m(-2); high: CI > 4.5 l min(-1) m(-2)). MEASUREMENTS AND RESULTS: In seven patients SST failed to measure CO. In the remaining 58 patients 314 paired CO measurements were performed. The mean time to measure CO by SST was 73 +/- 45 s. The equation of linear regression was: SST(CO) = 0.84 TD(CO) + 1.39. The correlation coefficient was 0.84. The bias between SST and TD was -0.2 +/- 1.4 l min(-1). Biases were -0.23 +/- 0.50, -0.20 +/- 0.68, and 0.25 +/- 0.92 l min(-1) m(-2) for low, normal, and high levels of CI, respectively. CONCLUSION: SST does not accurately measure CO but allows a rapid assessment of CI level in critically ill patients.

Training is required to improve the reliability of esophageal Doppler to measure cardiac output in critically ill patients.

OBJECTIVES: Assessment of and effect of training on reliability of esophageal Doppler (ED) versus thermodilution (TD) for cardiac output (CO) measurement. DESIGN: Prospective study. SETTING: Intensive care unit of a university hospital. PATIENTS: 64 consecutive critically ill patients requiring a pulmonary artery catheter, sedation, and mechanical ventilation. INTERVENTIONS: Esophageal Doppler CO measurements were performed by the same operator, whereas TD CO measurements were carried out by other independent operators. A training period involving the first 12 patients made the operator self-confident. In the remaining patients, the reliability of ED was assessed (evaluation period), using correlation coefficients and the Bland and Altman diagram. Between training and evaluation periods, correlation coefficients, biases, and limits of agreement were compared. MEASUREMENTS AND RESULTS: During training and evaluation periods, 107 and 320 CO measurements were performed in 11 out of 12 patients and in 49 out of 52 patients, respectively. Continuous CO monitoring was achieved in 6 out of 11 patients and in 38 out of 49 patients during training and evaluation periods, respectively. Between the two periods, correlation coefficients increased from 0.53 to 0.89 (p < 0.001), bias decreased from 1.2 to 0.1 l x min(-1) (p < 0.001), and limits of agreement decreased from 3.2 to 2.2 l x min(-1) (p < 0.001). CONCLUSION: A period of training involving no more than 12 patients is probably required to ensure reliability of CO measurement by ED.

Risk factors of failure and immediate complication of subclavian vein catheterization in critically ill patients.

OBJECTIVE: To identify the risk factors of failure and immediate complication of subclavian vein catheterization (SVC). DESIGN: Prospective observational study. SETTING: Surgical critical care unit of a tertiary university hospital. PATIENTS: Critically ill patients requiring a first SVC. INTERVENTION: Subclavian vein catheterization was attempted in 707 patients without histories of surgery or radiotherapy in the subclavian area. Failed catheterizations, arterial punctures, pneumothoraces and misplacements of the catheter tip were recorded. Risk factors of failure and immediate complication were isolated among patients' characteristics, procedure parameters (side and number of venipunctures) and the operator's experience using a univariate +/- multivariate analysis. MEASUREMENTS AND MAIN RESULTS: Five hundred sixty-two SVCs (79.5%) were achieved without adverse events. Among the remaining 145 catheterizations, 67 (9.5%) failures, 55 (7.8%) arterial punctures, 22 (3.1%) pneumothoraces and 30 (4.2%) misplacements of the catheter tip occurred. More than one venipuncture was the only risk factor of failed catheterization [2 venipunctures, odds ratio =7.4 (2.1-26); >2 venipunctures, odds ratio =49.1 (16.8-144.1)]. More than one venipuncture and age 77 years or more were predictive of the occurrence of immediate complications [2 venipunctures, odds ratio =3.6 (1.8-7.0); >2 venipunctures, odds ratio =14 (7.7-25.3); age >or=77, odds ratio =1.8 (1.0-3.1)]. The operator's training was not predictive of failed catheterization or immediate complication. CONCLUSION: For SVC, more than one venipuncture is predictive of failed catheterization and immediate complication. Age 77 years or more was predictive of immediate complications.

Comparison of the diagnostic value of cardiac troponin I and T determinations for detecting early myocardial damage and the relationship with histological findings after isoprenaline-induced cardiac injury in rats.

Cardiac troponins I (cTnI) and T (cTnT) have been shown to be highly sensitive and specific markers of myocardial cell injury. The purpose of this study was to investigate the diagnostic value of cTnI and cTnT with regard to creatine kinase (CK) and lactate dehydrogenase (LD) and to determine whether they can be used for early diagnosis of myocardial damage in rats, and to examine the relationship between cTnl and cTnT release with histological examinations, using isoprenaline-induced cardiac muscle damage as an experimental model in the rat. Eighteen Wistar rats per group were treated with a single dose of either isoprenaline (iso) or with normal saline as a control group. The anti-cTnI and cTnT monoclonal antibodies (mAbs) employed in the cTnI (Access) and cTnT (Elecsys) assays cross-react with cTnI and cTnT of the rat. A highly significant rise of cTnl or cTnT was found already 2 h after iso. The time-courses of cTnI and cTnT were monophasic in form. The highest cTnI (mean+/-S.D., 1.1+/-2.3 ng/ml) and cTnT (mean+/-S.D. 3.6+/-30 ng/ml) were found 4 h after iso. cTnI and cTnT significantly increased in iso-treated rats in comparison with controls whether the differences between 2-, 4- and 6-h levels and basal levels were considered or not. The areas under cTnl and cTnT curves (AUC) (0-6 h) and the maximal cTnI and cTnT (0-6 h) after iso were significantly different from the controls. For CK and LD, no elevation in comparison with controls could be detected (except a trend for LD whether or not the difference between 6-h levels and basal levels were considered (P=0.08) and for LD AUC (0-6 h) (P=0. 059)). Correlations between maximal cTnI and cTnT and AUC were 0.69 (P=0.0001) and 0.60 (P=0.0066), respectively. Histological examinations of iso-treated rats revealed acute focal or multifocal myofibrillar degeneration of the myocardial tissue in ten out of 14 rats and showed the earliest alterations 4 h after iso in one treated rat. Only four of the controls exhibited evidence of mild changes and slight mononuclear cell infiltration. cTnl and cTnT peak values to at least 0.35 and 1.3 ng/ml, respectively, were necessary to detect histological myocardial cell injury after iso. cTnI and cTnT were found to be early markers for diagnosing iso-induced myocardial damage in comparison with CK and LD. Elevations of cTnI and cTnT appeared to relate to the severity of histologic changes after myocardial injury. Although there was a difference in the absolute concentration of results between cTnI and cTnT assays, due to a lack of standardization and heterogeneity in the cross-reactivities of mAbs to various troponin I and T forms, cTnI and cTnT can be used as easily measurable target parameters for detection of cardiotoxic and/or cardiodegenerative effects in rats.

Time-course of cardiac troponin I release from isolated perfused rat hearts during hypoxia/reoxygenation and ischemia/reperfusion.

The study was designed to determine the time-course of cardiac troponin I (cTn-I) release in isolated and Langendorff-perfused rat hearts during hypoxia and reoxygenation (H/Reox), and after various durations of total ischemia and subsequent reperfusion (I/R). For this purpose, in H/Reox, cTn-I was measured with the conventional Access immunoassay (ng/ml) and a new immunoassay which operates at pg/ml, and compared with creatine kinase (CK), lactate dehydrogenase (LD) and cardiac troponin T (cTn-T). In I/R, cTn-I was compared with CK and LD. The anti-Tn-I mAbs used in cTn-I assays cross-react with cTn-I of the rat. A clear difference between time-courses and concentration levels of cTn-I in I/R and H/Reox models was found. In I/R, maximum release of cTn-I, CK and LD similarly occurred within minutes following reperfusion; however cTn-I did not return to baseline values. cTn-I levels were not linked to the duration of ischemia. In I/R, we were only able to detect small cTn-I concentrations. In H/Reox experiments, cTn-I, CK and LD increased time-dependently. We found higher cTn-I maximal peak levels detected with the Access immunoassay than with the new assay (median, 0.346 ng/ml per min/g dry wt vs 132 pg/ml per min/g dry wt). cTn-T maximal concentrations were lower than maximal cTn-I levels (median, 0.117 ng/ml per min/g dry wt). Time-courses of cTn-I release were roughly similar with both assays in the H/Reox model (r = 0.90). These data indicate that the cTn-I time-course is related to experimental model (I/R or H/Reox), but also likely depends on the sensitivity of cTn-I assays in such experimental conditions.

Evaluation of cardiac troponin I and T levels as markers of myocardial damage in doxorubicin-induced cardiomyopathy rats, and their relationship with echocardiographic and histological findings.

BACKGROUND: Cardiac troponins I (cTnI) and T (cTnT) have been shown to be highly sensitive and specific markers of myocardial cell injury. We investigated the diagnostic value of cTnI and cTnT for the diagnosis of myocardial damage in a rat model of doxorubicin (DOX)-induced cardiomyopathy, and we examined the relationship between serial cTnI and cTnT with the development of cardiac disorders monitored by echocardiography and histological examinations in this model. METHODS: Thirty-five Wistar rats were given 1.5 mg/kg DOX, i.v., weekly for up to 8 weeks for a total cumulative dose of 12 mg/kg BW. Ten rats received saline as a control group. cTnI was measured with Access(R) (ng/ml) and a research immunoassay (pg/ml), and compared with cTnT, CK-MB mass and CK. By using transthoracic echocardiography, anterior and posterior wall thickness, LV diameters and LV fractional shortening (FS) were measured in all rats before DOX or saline, and at weeks 6 and 9 after treatment in all surviving rats. Histology was performed in DOX-rats at 6 and 9 weeks after the last DOX dose and in all controls. RESULTS: Eighteen of the DOX rats died prematurely of general toxicity during the 9-week period. End-diastolic (ED) and end-systolic (ES) LV diameters/BW significantly increased, whereas LV FS was decreased after 9 weeks in the DOX group (p<0.001). These parameters remained unchanged in controls. Histological evaluation of hearts from all rats given DOX revealed significant slight degrees of perivascular and interstitial fibrosis. In 7 of the 18 rats, degeneration and myocyte vacuolisation were found. Only five of the controls exhibited evidence of very slight perivascular fibrosis. A significant rise in cTnT was found in DOX rats after cumulative doses of 7.5 and 12 mg/kg in comparison with baseline (p<0.05). cTnT found in rats after 12 mg/kg were significantly greater than that found after 7.5 mg/kg DOX. Maximal cTnI (pg/ml) and cTnT levels were significantly increased in DOX rats compared with controls (p=0.006, 0.007). cTnI (ng/ml), CK-MB mass and CK remained unchanged in DOX rats compared with controls. All markers remained stable in controls. Analysis of data revealed a significant correlation between maximal cTnT and ED and ES LV diameters/BW (r=0.81 and 0.65; p<0.0001). A significant relationship was observed between maximal cTnT and the extent of myocardial morphological changes, and between LV diameters/BW and histological findings. CONCLUSIONS: Among markers of ischemic injury after DOX in rats, cTnT showed the greatest ability to detect myocardial damage assessed by echocardiographic detection and histological changes. Although there was a discrepancy between the amount of cTnI and cTnT after DOX, probably due to heterogeneity in cross-reactivities of mAbs to various cTnI and cTnT forms, it is likely that cTnT in rats after DOX indicates cell damage determined by the magnitude of injury induced and that cTnT should be a useful marker for the prediction of experimentally induced cardiotoxicity and possibly for cardioprotective experiments.

Pharmacokinetics of hydroxocobalamin in dogs.

Hydroxocobalamin is a powerful cyanide antidote that prevents sodium nitroprusside-induced cyanide toxicity. The pharmacokinetics of an i.v. bolus of hydroxocobalamin (70 and 140 mg/kg) were studied in conscious dogs (n = 6). Plasma hydroxocobalamin concentrations were measured using derivative spectrophotometry. The pharmacokinetics were compatible with a two-compartment model with a first-order distribution and elimination rate, and pharmacokinetic parameters were not different between the two doses, except for the elimination half-life. At 70 mg/kg, which is the recommended dose in acute cyanide poisoning, the elimination half-life was 7.36 +/- 0.79 h, the volume of distribution was 0.49 +/- 0.10 L/kg, and the total clearance 0.58 +/- 0.11 L/h. At high doses, hydroxocobalamin has a short elimination half-life and a limited volume of distribution that exceeds blood volume. These results could be useful in elaborating guidelines for the administration of hydroxocobalamin, when repetitive bolus and/or continuous infusion is required.

[Humidification of the respiratory tract in anesthesia]. / Humidification des voies aériennes en anesthésie.

The upper airways humidify, warm and purify the air breathed in. When these are bypassed by an endotracheal intubation catheter, cold dry air goes straight to the bronchi; this leads to local and generalized changes, which are all the more pronounced the longer the intubation lasts. Drying of the tracheobronchial mucosa leads to an early decrease in mucus production, with an increase in its viscosity, a progressive arrest of ciliary function with, finally, a destruction of the vibratory cilia. These lesions create a build-up of thick mucus which hinders humidification of the gas flow and increases bronchial resistances. The disturbed VA/Q relationship leads to a decreased secretion of surfactant. The usual loss of water by way of the lungs is about 30 mg.l-1 of air. Evaporation of this water uses up calories. Most authors suggest that, so as to compensate for the heat and water loss, inhaled gases should be warmed to between 25 and 30 degrees C and be saturated with water to 100%, i.e. 23-30 mg water per litre of air. The water and heat loss can be reduced by using either partial or total rebreathing of expired gases, or a device for heat and moisture exchange, or a humidifier. The most efficient circuits are those which include a soda lime canister. They can be made even more efficient by using different devices. Although this humidification is sufficient for large tidal volumes and a surrounding temperature greater than 22 degrees C, it is not enough for Bain's circuit.(ABSTRACT TRUNCATED AT 250 WORDS)

[Mechanisms of the cardiac toxicity of bupivacaine]. / Mécanismes de la toxicité cardiaque de la bupivacaïne.

Of all the amide local anaesthetics, bupivacaine is said to be the most cardiotoxic. This toxicity is seen mostly when there is a sudden increase in the plasma concentration of bupivacaine. It involves both, or either, electrical and mechanical structures within the heart. The main site of action on cardiac conduction tissue is the Vmax of phase 0 of the action potential of fast-reacting structures (INa current). Bupivacaine, like lidocaine and the other class I antiarrhythmic drugs, blocks the sodium channels, this block being more slowly reversible. The disturbance of sodium channels throughout the heart leads to a decreased conduction speed throughout the conduction system, thus explaining possible acute conduction disturbances originating below the bundle of His. The ventricular dysrhythmias described are due to a re-entry circuit secondary to a slowing in conduction speed. However, the sinus bradycardias and junctional disturbances seen in toxic accidents are probably due to an inhibition of the slow current of the atrial and atrio-ventricular nodes (Isi current). The experimental observation of an increase in the atrial monophase potential and the corrected QT interval suggests that repolarization currents are also involved (IK current ?). It would therefore seem that modifications in membrane permeabilities are the cause of the seriousness of the clinical picture. Bupivacaine, at toxic levels, has a direct effect on contractility. The negative inotropic effects seem to be due to a fall in the intracytoplasmic calcium concentration on which depends the excitation-contraction couple, as well as disturbed cellular energetic events dependent on the contraction.(ABSTRACT TRUNCATED AT 250 WORDS)

[An aid in the diagnosis of cardiac rhythm disorders in anesthesia and intensive care]. / Aide au diagnostic des troubles du rythme cardlaque en anesthésie-réanimation.

Exact diagnosis of tachycardia was sometimes difficult to do as P waves were not easy to see on ECG. A simple device is described, with which ample P waves were recorded in patients with a central venous catheter. This catheter was used as conductor of cardiac electrical activity. It proved simpler and less aggressive for the patient in comparison with other techniques (intracardiac and oesophageal recording).

[Treatment of acute hepatic encephalopathy with flumazenil]. / Traitement de l'encéphalopathie hépatique aiguë par le flumazénil.

In animal studies as well as in a few cases in humans, the benzodiazepine antagonist flumazenil has been shown to reverse hepatic encephalopathy. The authors treated 3 patients with acute hepatic encephalopathy stage III or IV complicating cirrhosis. Two patients had an immediate recovery, maintained with a continuous infusion of flumazenil. In the third patient the clinical status dit not improve but the hepatic encephalopathy coexisted with major abnormalities in blood gases and electrolytes abnormalities, which could participate to the neurologic failure.

[Cardiac toxicity of bupivacaine and diazepam. Experimental study in the anesthetized dog]. / Toxicité cardiaque de la bupivacaïne et diazépam. Etude expérimentale chez le chien anesthésié.

The use of diazepam has been suggested for the treatment of convulsions resulting from accidental high plasma levels of local anaesthetics. However, it has been reported that this drug may increase the cardiac effects of bupivacaine in dogs. The present study aimed to assess the effects of diazepam on the electrophysiological signs of a high-dose intravenous bolus of bupivacaine in fourteen dogs, divided into two groups, and anaesthetized with thiopentone and ventilated. All the animals were given a bolus dose of 4 mg.kg-1 bupivacaine. Immediately afterwards, group I (n = 7) received 0.8 ml.kg-1 normal saline solution and group II (n = 7) was given 4 mg.kg-1 diazepam over 1 min. The parameters measured on lead II of the electrocardiogram were: cycle length (R-R interval), QRS length (QRS) and QT interval corrected for heart rate (cQT). Intranodal (AH) and His-Purkinje (HV) conduction times were measured with recording bipolar stimulation electrodes (USCI 6F). Mean aortic pressure (Pao) was measured via a femoral arterial line. In the two groups, the parameters were recorded before and 2, 5, 10 and 15 min after the bupivacaine bolus. Arterial blood samples for measurement of bupivacaine and diazepam serum levels were obtained before and 3, 15 and 30 min after the bupivacaine bolus. There was no significant difference between the two groups in the electrophysiological or haemodynamic parameters at any time. However, the increase in HV and QRS length was a little higher in group I than in group II.(ABSTRACT TRUNCATED AT 250 WORDS)