Does the Child Behavior Checklist predict levels of preoperative anxiety at anesthetic induction and postoperative emergence delirium? A prospective cohort study.

BACKGROUND: preoperative anxiety at induction and postoperative emergence delirium (ED) in children are associated with postoperative behavioral changes and adjustment disorders. This study's aim is to assess the value of the Child Behavior Checklist (CBCL) score in order to predict anxiety during induction and emergence delirium after anesthesia in children undergoing elective day-care surgery. METHODS: Anxiety at induction, assessed by the modified Yale Preoperative Anxiety Scale (mYPAS), was studied as outcome in 401 children (60.1% male, age range: 1.5-16 years). For 343 of these children (59.8% male, age range: 1.5-16 years) ED could be investigated postoperatively, as assessed by the Pediatric Anesthesia Emergence Delirium scale (PAED). Demographic data, healthcare contacts, anesthesia and surgical data were registered. Preoperative emotional/behavioral problems, during the 6 months prior to surgery, were assessed by the CBCL. Hierarchical, multiple regression was used to test whether anxiety and ED could be predicted by CBCL scores. RESULTS: Children with a higher CBCL score on preoperative internalizing problems (e.g. anxious/depression) showed preoperative more anxiety at induction (P=0.003). A higher CBCL score on preoperative emotional/behavioral problems was not associated with ED. CONCLUSION: The CBCL predicted anxiety at induction but not ED.

Belgian recommendations on perioperative maintenance fluid management of surgical pediatric population.

The European recommendations on perioperative maintenance fluids in children have recently been adapted from hypotonic to isotonic electrolyte solutions with lower glucose concentrations. In Belgium, however, the commercially approved solutions do not match with these recommendations and there is neither consensus nor mandate about the composition and volume of perioperative maintenance fluids in children undergoing surgery despite the continuing controversy in literature. This paper highlights the significant challenges and shortcomings while prescribing fluid therapy for pediatric surgical patients in Belgium. It is sensible to the authors to address these issues with national guidance through an organization such as The Belgian Association for Paediatric Anaesthesiology, and to propose Belgian recommendations on perioperative fluid management in surgical children, with the intention of improving the quality of care in this population.

Ultrasound as guidance for a combined bilateral supraclavicular and caudal block, in order to reduce the total anaesthetic dose in a two year old child after a pneumococcal sepsis.

We present a case of the combination of a bilateral supraclavicular block and a caudal block in a two year old boy who needed amputations of four extremities after a pneumococcal sepsis. With the use of ultrasound guidance, reduction of local anaesthetic dose could be obtained in order not to reach the toxic dose of the local anaesthetic. Amputations of four extremities is not common practice. A good postoperative pain management is more than a challenge.

An evaluation of underbody forced-air and resistive heating during hypothermic, on-pump cardiac surgery.

We conducted a randomised controlled trial to compare the efficacy of underbody forced-air warming (Arizant Healthcare Inc, Eden Prairie, MN, USA) with an underbody resistive heating mattress (Inditherm Patient Warming System, Rotherham, UK) and passive insulation in 129 patients having hypothermic cardiac surgery with cardiopulmonary bypass. Patients were separated from cardiopulmonary bypass at a core temperature of 35 °C and external warming continued until the end of surgery. Before cardiopulmonary bypass, the temperature-vs-time slopes were significantly greater in both active warming groups than in the passive insulation group (p < 0.001 for each). However, the slopes of forced-air and resistive warming did not differ (p = 0.55). After cardiopulmonary bypass, the rate of rewarming was significantly greater with forced-air than with resistive warming or passive insulation (p < 0.001 for each), while resistive warming did not differ from passive insulation (p = 0.14). However, absolute temperature differences among the groups were small.

A numerical study of the influence of ammonia addition on the auto-ignition limits of methane/air mixtures.

In this study the auto-ignition limit of ammonia/methane/air mixtures is calculated based upon a perfectly stirred reactor model with convective heat transfer. The results of four different reaction mechanisms are compared with existing experimental data at an initial temperature of 723 K with ammonia concentrations of 0-20 mol.% and methane concentrations of 2.5-10 mol.%. It is found that the calculation of the auto-ignition limit pressure at constant temperature leads to larger relative deviations between calculated and experimental results than the calculation of the auto-ignition temperature at constant pressure. In addition to the calculations, a reaction path analysis is performed to explain the observed lowering of the auto-ignition limit of methane/air mixtures by ammonia addition. It is found that this decrease is caused by the formation of NO and NO(2), which enhance the oxidation of methane at low temperatures.

[Quality dental care: a complex subject]. / Des soins bucco-dentaires de qualité: une matière complexe.

Assessing the quality of dental care depends on the approach. From the patient's perspective the perception of the quality of care depends as much on the pure technical quality of the treatment as on the level of patient - doctor communication, organisation and administration experienced in relation to the treatment. From the point of view of the dental professionals who tend to focus primarily on outcome of treatment on the other hand, this way of patient's judging integrated quality of care might be quite frustrating. After all, thanks to verbal and organisational skills, making good impression despite bad diagnostic and treatment quality might come within reach of simply every dental professional. As desirable it might be, is it possible anyhow to measure if the ultimate quality of care meets the standards of care patients deserve? Certifying outcome of treatment is difficult since it depends on too much variables amongst which some (such as patient's compliance) might fall out of reach of control of the dental care professionals. That's why modern clinical guidelines and protocols stress on creating the ideal treatment steps and conditions most likely leading to the most favourable treatment result. Finally authorities and policymakers aspire more and more to the idea of indicators measuring clinical quality of care from a cost effectiveness point of view. In this respect the authors state that cheap high quality dental care for everybody has become out of date in the actual context. And defining limits to quality of care in order to gain affordability or accessibility, is going to be a tricky exercise requiring sound scientific thinking balanced with ethics.

Calculation of the upper flammability limit of methane/air mixtures at elevated pressures and temperatures.

Four different numerical methods to calculate the upper flammability limit of methane/air mixtures at initial pressures up to 10 bar and initial temperatures up to 200 degrees C are evaluated by comparison with experimental data. Planar freely propagating flames are calculated with the inclusion of a radiation heat loss term in the energy conservation equation to numerically obtain flammability limits. Three different reaction mechanisms are used in these calculations. At atmospheric pressure, the results of these calculations are satisfactory. At elevated pressures, however, large discrepancies are found. The spherically expanding flame calculations only show a marginal improvement compared with the planar flame calculations. On the other hand, the application of a limiting burning velocity with a pressure dependence Su,lim approximately p(-1/2) is found to predict the pressure dependence of the upper flammability limit very well, whereas the application of a constant limiting flame temperature is found to slightly underestimate the temperature dependence of the upper flammability limit.

Resistive heating during off-pump coronary bypass surgery.

BACKGROUND: Maintaining normothermia during off-pump coronary artery bypass (OPCAB) surgery is difficult. The purpose of the present study is to determine the effect of the Inditherm Patient Warming System (IPWS) with standard institutional care during OPCAB surgery. METHODS: A control cohort of 10 patients undergoing OPCAB surgery received standard conventional therapy. A study cohort of another 10 patients then underwent similar procedures with the additional use of the IPWS. The nasopharyngeal and rectal temperatures of the two groups were compared during the 4-hour study period. RESULTS: During the 4-hour study period after induction, the Inditherm patients demonstrated significantly improved core body temperatures compared to the control group: lowest rectal temperature: 35.8 +/- 0.4 degrees C vs. 34.8 +/- 0.6 degrees C (p < 0.01) and lowest nasopharyngeal temperature : 35.5 +/- 0.4 degrees C vs. 34.7 +/- 0.5 degrees C (p < 0.01), respectively. The between-group rectal and nasopharyngeal temperature differences reached statistical significance after 70 minutes, 36.2 +/- 0.5 degrees C vs. 35.7 +/- 0.2 degrees C (p < 0.01) and after 60 minutes 35.8 +/- 0.4 degrees C vs. 35.4 +/- 0.1 degrees C (p < 0.01), respectively. At the end, the rectal core temperatures were 36.1 +/- 0.6 degrees C vs. 34.9 +/- 0.6 degrees C (p < 0.01) and the nasopharyngeal temperatures were 35.8 +/- 0.6 degrees C vs. 34.8 +/- 0.5 degrees C (p < 0.01) in the study and the control groups, respectively. CONCLUSION: The combination of the IPWS with standard thermal care provides higher core temperatures during OPCAB surgery.

Flammability limits and explosion characteristics of toluene-nitrous oxide mixtures.

Flammability limits and explosion characteristics of toluene-nitrous oxide mixtures are experimentally determined in an 8l spherical vessel, and are compared with corresponding values of toluene-air mixtures. The experiments, performed at atmospheric pressure and at an initial temperature of 70 degrees C, show that the flammable range of toluene in nitrous oxide (0.25-22.5 mol%) is about three times as wide as the corresponding range of toluene in air (1.3-7.1 mol%). Maximum values of the explosion pressure ratio and the deflagration index, K(G), are clearly higher when nitrous oxide is applied as an oxidizer. This can be attributed to the increased flame temperature and burning velocity of toluene-nitrous oxide flames. Moreover, extremely high values of K(G) for near-stoichiometric mixtures in combination with strong acoustic oscillations in the pressure signals of these mixtures indicate the existence of a flame accelerating mechanism. These phenomena are enhanced when an initial pressure of 6 bara is applied. Finally, when evaluating the lower flammability limit, it was found that pure nitrous oxide decomposes at pressures above 4.5 bara when applying an ignition energy of about 10 J.

Auto-ignition hazard of mixtures of ammonia, hydrogen, methane and air in a urea plant.

The auto-ignition of NH(3)/CH(4)/H(2)/air mixtures constitutes a hazard that is of much concern in urea plants. In this study, the auto-ignition behaviour of NH(3)/CH(4)/H(2)/air mixtures is investigated experimentally for pressures up to 7500 kPa. The experiments were carried out in a closed spherical vessel with a volume of 8 dm(3). The concentration and the pressure dependence of the auto-ignition temperature (AIT) were determined for four types of mixtures: NH(3)/air, NH(3)/CH(4)/air, NH(3)/H(2)/air and NH(3)/CH(4)/H(2)/air. The most ignitable NH(3)/air mixtures were situated between stoichiometry and the upper flammability limit. Small amounts of methane and hydrogen decrease the AIT of NH(3)/air mixtures to a large extent. The pressure dependence of the AIT could be correlated by a Semenov relationship. For the multi-fuel mixtures, a distinct deviation from the Semenov correlation was observed at the lowest temperatures. With respect to the explosion hazard in urea plants, the experimental results were used to assess realistic AIT values in the pool reactor and the ammonia scrubber, operating at a pressure of 15,000 kPa.

[Pitfalls to avoid in the cleaning and shaping of the pulp canal]. / Pièges à éviter lors du nettoyage et de la mise en forme de la cavité pulpaire.

Chemomechanical instrumentation of the root canal system is without doubt the most important but most challenging part of endodontic treatment. The first essential in cleaning and shaping is gaining direct access to the root canals. A properly prepared endodontic access opening can eliminate many of the technical problems encountered in root canal treatment. Excessive calcification in the root canal system and performing root canal treatment through existing artificial crowns however can be a challenge for the clinician. Secondly, enlargement of a curved root canal often results in loss of working length, incomplete removal or extrusion of the root canal content and unwanted alterations in the canal shape, such as transportation (stripping, zipping, elbow formation), ledge formation and perforation. This article focuses on the causes and effects of procedural errors during root canal cleaning and shaping. Each of these complications is addressed in a manner designed to prevent problems rather than to manage them once they are recognized. Throughout the immense amount of literature published the last 30 years on this topic, concensus is obtained concerning the preferential procedure of cleaning and shaping the root canal.

Experimental study of the flammability limits of toluene-air mixtures at elevated pressure and temperature.

The flammability limits of toluene-air mixtures are experimentally determined at pressures up to 500 kPa and temperatures up to 250 degrees C in a closed spherical vessel. The results at atmospheric pressure are compared with the results obtained in a glass tube. The flammability limits depend linearly upon temperature. A twilight zone characterized by weak pressure rises is observed for toluene at all pressures, while soot is formed at elevated pressures only. The explosion characteristics of toluene are compared with those of methane. Despite their chemical differences, the explosion characteristics of toluene and methane are similar.

Comparison of two standard test methods for determining explosion limits of gases at atmospheric conditions.

A comparison is made between two internationally accepted methods to determine the explosion limits of gases at atmospheric pressure and room temperature (20 l sphere - DIN 51649). Significant differences (about 1 vol.%) in the upper explosion limits (UEL) values are found for four hydrocarbons tested. A new criterion is proposed which leads to close agreement between the UEL values obtained by the two methods.

Dramatic response of recurrent invasive thymoma to high doses of corticosteroids.

We report the case of a widely invasive thymoma non-associated with myasthenia gravis which responded only to high doses of corticosteroids. We review the other few reported cases of complete response achieved by this treatment and we stress the possible use of high doses of corticosteroids in the management of recurrent invasive thymoma.

Analysis of the pressure perturbation due to the introduction of a measuring probe under an elastic garment.

Attention is drawn to the increase of the pressure on the skin due to the introduction of a measuring probe under an elastic garment. The increase of pressure is explained by looking at the force equilibrium on the transducer. Making some assumptions on the geometry and the conditions that actually prevail at the interface, this mechanical phenomenon is expressed mathematically. Expressions for estimating the order of magnitude of the relative pressure perturbation are derived both for the case of a cylindrical probe and for a thin plate probe with the same curvature as the limb. Thanks to the geometrical assumptions, these expressions are independent of the mechanical properties of the probe and the soft tissue. As in some of these formulas the magnitude of the indentation appears, a measurement is necessary for estimating the error. Other expressions, only taking in account the dimensions of the limb and the probe, give a rougher estimation of the error. It is shown through a few practical examples that the error cannot be disregarded and cannot be calculated precisely, which means that this measuring technique is unreliable. The same mathematical expressions are used to show that pressure paddings effectively increase the pressure. It is also shown that the introduction of an optical fibre under the garment, used in laser Doppler flowmetry, creates an important additional pressure on the skin.