[European normative recommendations for medical gas pipeline systems]. / Normalisation européenne et systèmes de distribution de gaz médicaux.

Several recent decisions have been made in order to increase the security of medical gases delivery in French hospitals. These different changes affect: 1) the hospital itself with the creation of working groups in charge of both monitoring and maintenance of gases networks; 2) the pharmaceutical regulation with promotion of several gases to the status of drugs or need of CE marking for the whole gas network. European rules onset required to give up French former norms (NF) to the profit of "NF EN" rules. Nevertheless, the new norm NF EN 737-3 which concerns medical gases distribution systems does not affect principal clauses of the previous NF S 90-155. It introduces new elements allowing to deploy two types of medical gases networks: the double pressure level used in France and the single pressure level used in the rest of Europe. This new norm, which attempts to harmonize alarm control systems in both types of networks, suffers from important limitations describing the double pressure level systems. Lastly, the final checking proposed by this new norm is very different from the previous one, and is likely to be problematic for the final users within the hospital.

Benzodiazepine anesthesia in humans modulates the interleukin-1 beta, tumor necrosis factor-alpha and interleukin-6 responses of blood monocytes.

The influence of sedative and anxiolytic benzodiazepines on human monocyte function was assessed in 11 patients undergoing anesthesia prior to control endoscopy of the urinary tract. A single i.v. injection of 0.08 mg/kg midazolam induced a marked and delayed inhibition of the lipopolysaccharide-induced production of interleukin-1 beta, tumor necrosis factor-alpha and interleukin-6 by monocytes isolated from peripheral blood. Corticosteroids were not responsible for the observed immunosuppression. These studies demonstrate that, when administered in man, benzodiazepines markedly alter the capacity of monocytes to synthetize major mediators of the host inflammatory response.

[The Medical Device Surveillance Central Commission. Evaluation and perspectives]. / La matériovigilance à l'échelon central. Bilan et perspectives.

In France, a national surveillance commission for medical devices ("Commission de Matériovigilance") functions to a) analyse declarations of incidents/accidents occurring or liable to occur with medical devices; b) propose preventive measures; c) propose surveys or studies concerning the practice of materiovigilance. One of the eight sub-commissions is in charge of the problems raised by devices used in anaesthesia and intensive therapy. The commission considered 406 alarm forms in 1996, 986 in 1997 and 1,200 were expected to arrive in 1998. This strong increase is observed because users of medical devices have become aware that declaration of incidents/accidents has become compulsory and because of the medico-legal risk. With the generalisation of local correspondents for materiovigilance and their filtering office, the amount of significant declarations reaching the national commission is expected to decrease. Among the 624 fully processed "alarm forms", at the time of writing this article, 407 (65%) were incidents without or only with minor consequences, 206 (33%) were significant accidents and 11 (2%) were associated with a lethal outcome. Non compliance with the instructions for use and a failure of the device were the main causes for incidents/accidents. Major corrective measures were mainly taken for misconceptions and quality insurance in production of the devices.

[Electric infusion devices: criteria of choice and comparative analysis of 45 models available in France]. / Appareils électriques de perfusion: critères de choix et analyse comparative de 45 modèles disponibles en France.

This study compared 45 electric infusion devices, either constant flow pumps or syringe pumps, available in France. These devices were tested for start-up delay, time to alarm following occlusion, bolus following occlusion, accuracy of flow rate and pressure output. Ergonomic, environmental and various technical criteria such as safety in continuous perfusion, correct positioning of infusion sets, air in line and end of perfusion detection were also considered. Users can compare these devices in easy to read tables. The newest devices include systems improving the quality of flow.

[Electric infusion devices]. / Les appareils électriques de perfusion.

Electrical infusion devices are specifically aimed to maintain an accurate and constant flow rate. The infused agents can be allocated into three categories of risk, according to their therapeutical index and their infusion rate. Each category requires infusion devices with the corresponding performances. Moreover the choice of a device depends also on ergonomical and environmental criteria as the area of use (e.g. ambulatory patient, transport, neonates, intravenous anaesthesia).

[Defective gas mixers, a cause of retro-pollution of medical gas distribution pipelines]. / Mélangeurs de gaz défectueux, cause de rétropollution du circuit de distribution des gaz médicaux.

A defective Air/O2 mixer of a ventilator located downstream of the gas outlets of two pipelines is a potential cause of retropollution. Retropollution of O2 with Air or vice versa carries a risk of either a) a hypoxic gas mixture delivery during anaesthesia, including O2-N2O administration, when the O2 pipeline supplies Air instead of O2, or b) a hyperoxic gas mixture delivery in the intensive therapy unit for neonates during administration of a O2-Air mixture, when the Air pipeline supplies O2 instead of Air. A defective O2/N2O flowmeter-mixer of an anaesthesia machine, with N2O flow control by O2 through a differential pressure manometer, can cause retropollution of O2 supply pipeline with N2O or vice versa. The prerequisite for retropollution is the association of three events: build-up of a pressure difference between the two gas lines; defective or absent back-flow check value in the circuit of the gas at a lower pressure; one of the following defects: a) the pressure equilibrating valves of the mixer cannot amend the pressure difference and allow a gas reflow at the gas mixture outlet; b) leak in the diaphragm of a pressure equilibrating valve; c) defective bypass supply valve. The optimal means for the recognition of a pipeline contamination by another gas is the O2 analyzer, especially in anaesthetic areas where the presence of N2O and Air carries the risk of a hypoxic gas mixture delivery. The mixer or flowmeter-mixer responsible for retropollution can be recognized in plunging successively the various quick couplers underwater into a glass, while the others remain connected to their outlets and the mixer set at a O2 concentration of 50 vol% or the flowmeters set at a similar flow. In case of retropollution, the gas reflow produces bubbles. It is recommended: a) in anaesthetic areas to set the O2 pressure at about 0.2 bar above that of Air and the latter at a pressure of about 0.2 bar above that of N2O; b) in intensive therapy units for neonates, to set the Air pressure at about 0.2 bar above that of O2; c) in all areas to disconnect from the gas outlets the devices equipped with a mixer or a flowmeter-mixer when not in use.

[Equipment surveillance of implantable catheter ports (1996-1998). Members of Sub-Commissions 4a and 4b for Equipment Surveillance]. / Matériovigilance des chambres à cathéter implantables en France (1996-1998). Les Membres des Sous-Commissions 4a et 4b de Matériovigilance.

We analyse all incident reports to the French Health Ministry over the 1996-1998 period, concerning implantable catheter ports. They represent 7% of all reports in the field of anaesthesia and intensive care. Two hundred eleven reports have been analysed. There were 93 catheter ruptures with 77 intravascular migrations. In more than 50% of cases, a pinch-off syndrome mechanism was responsible of these ruptures and a displacement of the O'ring was involved in 25%. Additional minor complications were reported and discussed in regard to literature. We conclude that implantable catheter ports may lead to serious incidents which are preventable in most cases.

[Pollution and retro-pollution by the distribution system of medical gases]. / Pollution et rétropollution du réseau de distribution d'un gaz médical.

The anaesthetic machine, the recovery room or the ICU ventilator as well as any other simple oxygenation device can be accidentally supplied with a "wrong" gas, or a mixture of "wrong" and "true" gases, or a gas containing chemical impurities, as a result of one of the following causes: a) the source of the medical gas pipeline supply contains a "wrong" gas or impurities; b) the gas pipeline is polluted by a "wrong" gas or solvents, introduced during the installation or maintenance of the pipeline; c) the pipeline is polluted by a wrong gas at a point of inter-connection or cross-connection of two pipelines; d) supply of a "wrong" gas through wrong quick couplers connected to the pipeline; e) back flow of a gas in another pipeline supply through a defective gas mixer, which is today the most common cause of pipeline contamination or retropollution. It occurs with some types of mixers in case of absence or malfunction of non-return valves, associated with a pressure difference between the two gas lines. The means of prevention, recognition and emergency treatment of these events include: a) systematic removal of mixers and flowmeter-mixers from supplies when not in use; b) periodical checking of these devices for an accidental communication between the gases to be mixed; c) systematic use of an oxygen analyser for a continuous measurement of FIO2, especially when the machine is connected to the N2O pipeline supply; d) the presence of a reserve cylinder of oxygen connected to every anaesthetic machine.

[Pros or cons of accessory anesthetic circuits. I. Arguments for their use]. / Pour ou contre les circuits anesthésiques accessoires. I. Arguments pour leur utilisation.

In addition to the circle breathing system, which represents the main circuit of the anaesthetic machine, the use of an accessory breathing system (ABS), either a partial rebreathing system according to Mapleson's classification, or a system including a non-rebreathing valve, is appropriate for the anaesthetic management of many patients, depending on their physical status, age, indication and duration of surgery. The same safety rules, namely full checking procedure before use of the system and monitoring of inhaled gases and end-tidal CO2 must be applied as for the main circle system. Potential complications resulting from non compliance with these rules cannot be considered valuable reasons for denying the use of breathing systems that have safely been used for decades in millions of patients.

[Target-controlled intravenous anesthesia]. / Anesthésie intraveineuse à objectif de concentration.

Target-controlled infusion (TCI) is a new delivery system for i.v. anaesthetic agents with which the anaesthetist targets a plasma drug concentration to achieve a predetermined effect. With this system, the tedious task of calculating the amount of administered drug required to achieve the target concentration is left in charge of a microprocessor which commands the infusion device. TCI has long been used only by a few research teams, but this year a much wider field opens to this delivery system through marketing of Diprifusor, a TCI system specifically designed for administration of propofol in everyday practice. This article describes the rationale for administering i.v. agents through TCI delivery systems, the pharmacokinetic basis of TCI, the regulations and a broad overview of clinical applications, both recent and yet to come.

[Wrong connection of a flexible medical air hose to a nitrous oxide outlet caused by a defective safety device]. / Erreur de branchement d'un flexible d'air médical sur une prise de protoxyde d'azote par défaillance du système détrompeur.

When plugging the O2, N2O and air hoses into the corresponding wall sockets, the air hose was wrongly inserted into the N2O wall outlet. This was made possible because of faulty retaining clasps of the male coupler of the air probe. French "fail-safe" connections consist of a two-clasp male coupler for air, three clasps for O2 and four clasps for N2O hoses. Additionally the clasps of the air probe are broader then those of the N2O probe. However, the latter difference was lost due to wear. The incident was recognized without delay as the N2O hose could not be inserted into the air outlet. However, it could have remained unnoticed had there been two N2O wall outlets and could have resulted in severe adverse effects.

[Anesthetic equipment: fresh gas delivery systems. II. Electronic systems]. / Appareil d'anesthésie: systèmes d'alimentation en gaz frais. II. Systèmes électroniques.

OBJECTIVES: To analyse the design, functioning, benefits and drawbacks of electronic fresh gas delivery units (FGDUs) included in anaesthetic machines marketed in France in 1999. DATA SOURCES: Articles were obtained from a Medline review (1980-1999; search terms: anaesthetic machine, flowmeter, vaporizer), textbooks and personal files; specific data were also provided by manufacturers. STUDY SELECTION AND DATA EXTRACTION: The articles were analysed in considering the differences between mechanical and electronic FGDUs. DATA SYNTHESIS: Four anaesthetic machines out of 11 are equipped with electronic FGDUs. In comparison to mechanical units, they include the following benefits: wide range of accurate gas flow, especially in the low flow range, with analog and digital display; intermittent delivery of each gas, which is essential for automated gas delivery and quantitative anaesthesia or target controlled (FET vapor) inhalational anaesthesia; facilitated oxygen ratio control; possibility to print the gas and vapor flows on the automated anaesthetic record; interruption of gas flow when the main switch of the machine is set to off; and absence of risk for retropollution. Three FGDUs out of four are adapted for gas delivery to an accessory (ancillary) anaesthetic circuit. However, only one of them delivers a gas flow up to 30 L.min-1. The specificity of the ADU AS/3 (Datex-Ohmeda) is the bypass vaporizer included in the FGDU with an exchangeable vaporizing chamber (cassette). The specificity of the Julian (Dräger) is the delivery of fresh gas limited to the expiratory phase during mechanical ventilation. The specificity of the the FGDU from Kion (Siemens) is the possibility to act as an open circuit ventilator, similar to a Servoventilator. The specificity of the PhysioFlex is an FGDU included in the circle circuit, each gas and liquid anaesthetic being directly injected into the circuit. Data from the French medical device surveillance commission indicate that the main failures occur in the power supply device and the microprocessor.

[Anesthesia equipment: fresh gas delivery systems. I. Mecanical systems with rotameters and calibrated vaporizers]. / Appareil d'anesthésie: systèmes d'alimentation en gaz frais. I. Systèmes mécaniques avec rotamètres et vaporisateurs calibrés.

OBJECTIVES: To analyse the design, performance, failures, the checking before use of mechanical fresh gas delivery units (FGDUs) equipped with bobbin or ball-flowmeters delivering a continuous gas flow and calibrated vaporizers, marketed in France in 1999. DATA SOURCES: Articles were obtained from a Medline review (1960-1999; search terms: anaesthetic machine, flowmeter, vaporizer), textbooks and personal files; specific data were provided by manufacturers. STUDY SELECTION AND DATA EXTRACTION: The articles were considered for performance data, benefits and drawbacks, and characteristics, as well as the risks carried by mechanical FGDUs. DATA SYNTHESIS: Seven anaesthetic machines out of 11 are equipped with mechanical FGDUs, including rotameters delivering a gas mixture up to 30 L.min-1, calibrated vaporizers and an O2-flush valve delivering at least 500 mL O2 per second (30 L.min-1). These units allow closed circuit anaesthesia. They carry a risk for barotrauma as three out of them can deliver at the gas outlet of the FGDUs a gas mixture at a pressure reaching 3.5 bars and four others at a pressure of 150-200 mmHg. They also carry a risk for hypoxia, either from a preferential leak of oxygen at the corresponding rotameter or the O2-flush valve, or from a leak of fresh gas mixture either in a vaporizer or the selectatec manifold. The vaporizers carry a risk for vapor delivery at a concentration differing notably from the value set on the concentration dial. Therefore their accuracy must be checked periodically and the FGDUs checked for a leak after the addition to or the removal of a vaporizer from the selectatec manifold. The optimal technique for leak detection is the negative pressure test.

[Target controlled infusion (TCI) anesthesia using propofol. Assessment of training and practice in the operating room]. / Anesthésie intraveineuse à objectif de concentration (Aivoc) avec le propofol. Evaluation des formations et pratiques au bloc opératoire.

OBJECTIVE: To evaluate overall awareness of TCI and the need for training in the TCI technique. To assess, among trained anaesthetists, the value of the session and the impact of TCI technique on their working practice. STUDY DESIGN: Two prospective domestic surveys during the first quarter of 1999. METHODS: Three hundred anaesthetists representative of French anaesthetists as a whole, and 336 anaesthetists who had taken part in a training course. RESULTS: The notoriety of TCI was high and greater in the public sector compared with the private sector. Almost 3/4 of anaesthetists believed that training was necessary but only four anaesthetists out of ten TCI users said they had taken part in training sessions. After the training session nine anaesthetists out of ten became TCI users and would have recommended the training course despite the low number and variety of anaesthetic procedures observed during the practical part of training. The main difficulties reported during initial use were the choice of target concentrations and the management of drug interactions. Familiarisation to the technique was rapid (less than 20 procedures). Despite the lack of long experience (< 6 months for more than 2/3 of them), TCI appeared to be more likely used for anaesthesia of average duration. CONCLUSIONS: TCI was perceived to be an innovative concept with a requirement of a specific training. This preliminary appraisal of training sessions was generally satisfactory but underline a need for future training sessions focused on practical aspects.

[Anesthesia ventilators]. / Ventilateurs d'anesthésie.

OBJECTIVE: To review anaesthesia ventilators in current use in France by categories of ventilators. DATA SOURCES: References were obtained from computerized bibliographic search. (Medline), recent review articles, the library of the service and personal files. DATA SYNTHESIS: Anaesthesia ventilators can be allocated into three groups, depending on whether they readminister expired gases or not or allow both modalities. Contemporary ventilators provide either constant volume ventilation, or constant pressure ventilation, with or without a pressure plateau. Ventilators readministering expired gases after CO2 absorption, or closed circuit ventilators, are either of a double- or a single-circuit design. Double-circuit ventilators, or pneumatical bag or bellows squeezers, or bag-in-bottle or bellows-in-bottle (or box) ventilators, consist of a primary, or driving circuit (bottle or box) and a secondary or patient circuit (including a bag or a bellows or membrane chambers). Bellows-in-bottle ventilators have either standing bellows ascending at expiration, or hanging bellows, descending at expiration. Ascending bellows require a positive pressure of about 2 cmH2O throughout exhalation to allow the bellows to refill. The expired gas volume is a valuable indicator for leak and disconnection. Descending bellows generate a slight negative pressure during exhalation. In case of leak or disconnection they aspirate ambient air and cannot act therefore as an indicator for integrity of the circuit and the patient connection. Closed circuit ventilators with a single-circuit (patient circuit) include a insufflating device consisting either in a bellows or a cylinder with a piston, operated by a electric or pneumatic motor. As the hanging bellows of the double circuit ventilators, they generate a slight negative pressure during exhalation and aspirate ambient air in case of leak or disconnection. Ventilators not designed for the readministration of expired gases, or open circuit ventilators, are generally stand-alone mechanical ventilators modified to allow the administration of inhalational anaesthetic agents.

[Fatal pulmonary leukoagglutination after administration of fresh frozen plasma]. / Leucoagglutination pulmonaire mortelle après administration de plasma frais congelé.

A case is reported of a 73 year old female patient who died during surgery for enlarged nephrectomy as a result of a massive non-cardiogenic pulmonary oedema. She had been given 2 red cell concentrates (450 g) and 3 fresh frozen plasma units (900 g). A postmortem examination did not reveal any pulmonary embolus, acute myocardial infarct, haemorrhage or cardiac tamponade. Further tests on the sera of the 5 plasma donors revealed a neutrophil-specific anti-NA2 antibody. Alveolar leukostasis was confirmed on the postmortem lung slices. This type of transfusion accident occurs for about 1 in 5,000 units transfused, fortunately not all as serious. This case confirms once more that fresh frozen plasma is not the ideal treatment for acute hypovolaemia, 4% human albumin being safer.

[Perfusion instruments: analysis of product surveillance in 1998 and its on-the-job training. Subcommittee 4b for Product Surveillance]. / Matériels de perfusion: le bilan de la matériovigilance en 1998 et ses enseignements pour la pratique. Sous-commission 4b de matériovigilance.

OBJECTIVES: To analyze retrospectively the data base of the French national vigilance reporting system concerning infusion devices during the year 1998. METHODS: Each report has been reviewed and classified, except implantable catheter ports. RESULTS: The study included 309 reports. Among them, 28% concerned infusion pumps and 72% single use devices, i.e. catheters, infusion lines, taps, connectors, etc. We observed six deaths and 23 severe incidents. Only 25% of devices could be formally investigated by manufacturers. The origins of incidents were very different between infusion pumps and single use devices. The first showed simple failures, software errors, maintenance omissions or errors, and problems related to obsolescence of the device. The second revealed manufacturer quality insurance failures, design and utilization errors, and problems related to the technique itself rather than device. DISCUSSION: Our findings are similar to the few data available in international literature. They address the need to obtain an adequacy between the performances of devices which vary with generations of devices and the clinical risks: newest and safest devices should be preferred for the infusion of the most critical drugs.

[Ventilators for anesthesia. Models available in France. Criteria for choice]. / Appareils d'anesthésie. Modèles disponibles en France. Critères de choix.

This update article discusses the criteria for the choice of an anaesthetic machine and provides a short analysis of the main components of the models commercialized in France in 1994. The following items are considered: the design of the machine, the fresh gas delivery system, the anaesthesia breathing system(s), the ventilator and the waste gas scavenging system, the monitors associated with the machine and other criteria such as facility of learning to run the machine and of its daily use, ease of "in-house" maintenance and quality of after-sales service, cost of the machine and of its use (driving gas, disposable equipment).

[Accessory anesthetic breathing systems: verification before use]. / Circuits anesthésiques accessoires: vérification avant utilisation.

Accessory or ancillary anaesthesia breathing systems can be defined as all those connected to the fresh gas outlet of the anaesthetic apparatus and used instead of the circle system associated with the ventilator, which is the main circuit. They include: the Mapleson systems, the systems with a nonrebreathing valve and the disposable systems with a carbon dioxide absorber. They can be a cause of major accidents when not checked before and monitored during use. This technical note describes techniques of preanaesthetic checking and monitoring during anaesthesia.

[High frequency injection ventilation in laryngeal surgery. Methods and indications]. / La ventilation par injection à haute fréquence dans la chirurgie du larynx. Réalisation et indications.

High frequency injection ventilation was employed in 150 patients during endoscopy or laryngeal surgery. Lower mean intratracheal pressures are obtained that by conventional injection ventilation, and the respiratory pathways are protected to a greater degree. The reduced diameter of the tracheal approach provided by the use of a small transglottic catheter or a small intercricothyroidal tube enables the operative zone to be well exposed. For optimal efficacy, the method requires a frequency, equal to or less than 150 per minute, a short insufflation period, and sufficient exposure of the respiratory tract. General anesthesia is required.