Helium in the adult critical care setting

Helium is a low-density inert gas whose physical properties are very different from those of nitrogen and oxygen. Such properties could be clinically useful in the adult critical care setting, especially in patients with upper to more distal airway obstruction requiring moderate to intermediate levels of FiO2. However, despite decades of utilization and reporting, it is still difficult to give any firm clinical recommendation in this setting. Numerous case reports are available in the context of upper airway obstruction of different origins, but there is a lack of controlled studies for this indication. One study reported a helium-induced beneficial effect on surrogates of work of breathing after extubation in non-COPD patients, possibly in relation to laryngeal consequences of tracheal intubation. Physiological benefits of helium-oxygen breathing have been demonstrated in the context of acute severe asthma, but there is a lack of large controlled studies demonstrating an effect on pertinent clinical endpoints, except for a study reported only as an abstract, which mentioned a reduction in the intubation rate in helium-treated patients. Finally, there are a number of physiological studies in the context of COLD-COPD patients demonstrating a beneficial effect, mainly by a reduction in the resistive inspiratory work of breathing but also by a reduction in hyperinflation. Reduction of hypercapnia was mainly observed in spontaneously breathing and noninvasively ventilated helium-treated patients but not in intubated patients during controlled ventilation, suggesting that the decrease in PaCO2 was mainly in relation to a diminution in CO2 production, related to the diminution in work of breathing and not an improved alveolar ventilation. Moreover, there is little evidence that helium-oxygen could improve parameters of heterogeneity in such patients. Two RCTs were unable to demonstrate a reduction in the intubation rate in such setting, but they were likely underpowered. An adequately powered international multicentric study is ongoing and will help to determinate the exact place of the helium-oxygen mixture in the future. The place of the mixture during the weaning period will deserve further evaluation

Comparison of the Airtraq® and Truview® laryngoscopes to the Macintosh laryngoscope for use by Advanced Paramedics in easy and simulated difficult intubation in manikins

<p>Abstract</p> <p>Background</p> <p>Paramedics are frequently required to perform tracheal intubation, a potentially life-saving manoeuvre in severely ill patients, in the prehospital setting. However, direct laryngoscopy is often more difficult in this environment, and failed tracheal intubation constitutes an important cause of morbidity. Novel indirect laryngoscopes, such as the Airtraq^®and Truview^®laryngoscopes may reduce this risk.</p> <p>Methods</p> <p>We compared the efficacy of these devices to the Macintosh laryngoscope when used by 21 Paramedics proficient in direct laryngoscopy, in a randomized, controlled, manikin study. Following brief didactic instruction with the Airtraq^®and Truview^®laryngoscopes, each participant took turns performing laryngoscopy and intubation with each device, in an easy intubation scenario and following placement of a hard cervical collar, in a SimMan^®manikin.</p> <p>Results</p> <p>The Airtraq^®reduced the number of optimization manoeuvres and reduced the potential for dental trauma when compared to the Macintosh, in both the normal and simulated difficult intubation scenarios. In contrast, the Truview^®increased the duration of intubation attempts, and required a greater number of optimization manoeuvres, compared to both the Macintosh and Airtraq^®devices.</p> <p>Conclusion</p> <p>The Airtraq^®laryngoscope performed more favourably than the Macintosh and Truview^®devices when used by Paramedics in this manikin study. Further studies are required to extend these findings to the clinical setting.</p

Comparison of the Airtraq® and Truview® laryngoscopes to the Macintosh laryngoscope for use by Advanced Paramedics in easy and simulated difficult intubation in manikins

<p>Abstract</p> <p>Background</p> <p>Paramedics are frequently required to perform tracheal intubation, a potentially life-saving manoeuvre in severely ill patients, in the prehospital setting. However, direct laryngoscopy is often more difficult in this environment, and failed tracheal intubation constitutes an important cause of morbidity. Novel indirect laryngoscopes, such as the Airtraq^®and Truview^®laryngoscopes may reduce this risk.</p> <p>Methods</p> <p>We compared the efficacy of these devices to the Macintosh laryngoscope when used by 21 Paramedics proficient in direct laryngoscopy, in a randomized, controlled, manikin study. Following brief didactic instruction with the Airtraq^®and Truview^®laryngoscopes, each participant took turns performing laryngoscopy and intubation with each device, in an easy intubation scenario and following placement of a hard cervical collar, in a SimMan^®manikin.</p> <p>Results</p> <p>The Airtraq^®reduced the number of optimization manoeuvres and reduced the potential for dental trauma when compared to the Macintosh, in both the normal and simulated difficult intubation scenarios. In contrast, the Truview^®increased the duration of intubation attempts, and required a greater number of optimization manoeuvres, compared to both the Macintosh and Airtraq^®devices.</p> <p>Conclusion</p> <p>The Airtraq^®laryngoscope performed more favourably than the Macintosh and Truview^®devices when used by Paramedics in this manikin study. Further studies are required to extend these findings to the clinical setting.</p

Performances lors d'un exercice intermittent anaérobie: comparaison entre enfants et sujets matures

International audienceDesign.The purpose of the study was to compare the ability of children and mature subjects to repeat 20 s anaerobic exercises.Methods.Twelve children (11.6 ± 1.0 years old) and 12 mature subjects (18.4 ± 2.4 years old) performed a maximal aerobic test and an intermittent anaerobic test. For the latter, they had to repeat 6 all-out 20 s runs with 1 min passive recovery between repetitions. For both tests, blood lactate concentration was measured from capillary samples taken after 2 and 20 min recovery. Heart rate was continuously recorded.Results.For the intermittent anaerobic test, the decrease in performance between the first and sixth runs was greater in mature subjects than in children (15% vs 7%, P < 0.001). Post-exercise lactate ions concentration was higher in mature subjects than in children (17.2 ± 3.6 vs 12.0 ± 1.7 mmol.l−1 P < 0,001). However, lactate decrease rates (%·min−1) calculated between the second and twentieth minutes of recovery were similar in children and in mature subjects. Finally, during recovery between repetitions, the heart rate decrease was significantly faster in children than in mature subjects.Discussion and conclusion.As compared with mature subjects, children have a greater ability to repeat anaerobic exercises. This may be explained by a lower anaerobic contribution, or a higher aerobic contribution during exercises and by faster recovery.Objectifs.Comparer l'aptitude d'enfants et de sujets matures à répéter des exercices de 20 secondes sollicitant la filiére anaérobie.Méthodes.Douze enfants (11,6 ±1,0 ans) et 12 sujets matures (18,4 ± 2,4 ans) réalisent un test maximal aérobie et un test intermittent anaérobie. Lots de ce second test, les sujets ont à parcourir six fois la plus grande distance possible en 20 secondes. Les répétitions sont entrecoupées d'une minute de récupération passive. Lors des deux tests, des prélèvements sanguins capillaires sont effectués aux 2e et 20e minutes de récupération afin de mesurer les concentrations en ions lactate. La fréquence cardiaque est enregistrée en continu.Résultats.Lors du test intermittent anaérobie, la diminution de performance entre la 1re et la 6e répétition est moins importante chez les enfants que chez les sujets matures (7 % contre 15 %, p < 0,001). Les sujets matures sont caractérisés par des concentrations en ions lactate post-exercice supérieures à celles des enfants (17,2 ±3,6 contre 12, 0 ± 1,7 mmol.l−1, p < 0,001). En revanche, les taux de récupération du lactate (%·min−1) calculés entre les 2e et 2e minutes de récupération sont comparables chez l'enfant et le sujet mature. Enfin, lots de la récupération entre les répétitions, la diminution de fréquence cardiaque est plus rapide chez l'enfant que chez le sujet mature.Discussion et conclusion.Les résultats de cette étude indiquent que l'enfant arrive à répéter des exercices anaérobies à une plus haute intensité relative que le sujet mature. Cette différence peut s'expliquer par une sollicitation moindre de la filiére anaérobie lactique lors de l'exercice intermittent, ou par une contribution plus importante des processus oxydatifs, et par des possibilités de récupération plus rapides chez l'enfant

Fréquence cardiaque chez des adolescents âgés de 11 à 16 ans lors de séances d'éducation physique intensifiées

International audienceSummary – Heart rate in adolescents aged 11 to 16 during intensified physical education lessons. Introduction – Exercise physiologists notice sometimes that Physical Education (PE) sessions are lacking of intensity. This lack of intensity would not allow obtaining desired physiological responses. Thus, we measured heart rate (HR) in adolescents (boys and girls) aged 11–16 years old during intensified EP lessons.Method and results – Sessions consisted in short intermittent running (G1) and jumping exercises (G2). Heart rate was averaged over 30 min. There was no significant difference between mean HR for G1 and G2 (154 ± 12 vs 155 ± 12 bpm, p < 0.001). Nevertheless, for both G1 and G2, mean HR was significantly higher for girls than for boys (153 ± 12 vs 156 ± 12 bpm, p < 0.001).Conclusion – This type of intensified lessons request at a high level adolescents HR (75.4 ± 5.4% of maximal HR) to reach health objectivesIntroduction – Les physiologistes de l’exercice constatent parfois que les séances d’éducation physique et sportive (EPS) manquent d’intensité. Ce manque d’intensité ne permettrait pas d’obtenir les réponses physiologiques souhaitées. De ce fait, nous avons mesuré la fréquence cardiaque (Fc) d’adolescents (garçons et filles) âgés de 11 à 16 ans lors de séances d’EPS intensifiées.Méthode et résultats – Les séances comprenaient des exercices intermittents courts de course (G1) ou de bondissements (G2). La Fc était moyennée sur une durée de 30 min. Il n’y avait pas de différence significative entre la Fc moyenne de G1 et G2 (154 ± 12 contre 155 ± 12 bpm). En revanche, pour G1 et G2, les valeurs de FC moyennes étaient significativement supérieures chez les filles (153 ± 12 contre 156 ± 12 bpm, p < 0,001). Conclusion – Ce type de séance intensifiée sollicite à un niveau élevé la FC des adolescents (75,4 ± 5,4 % de Fc maximale) et permet de poursuivre des objectifs de santé

High-intensity aerobic training during a 10 week one-hour physical education cycle: effects on physical fitness of adolescents aged 11 to 16.

International audienceThe aim of this study was to analyse the effects of a high-intensity aerobic training program on different components of physical fitness in adolescents aged 11 to 16 years. The subjects were divided into a high intensity (HI) group (243 girls and 260 boys) and a control (C) group (21 girls and 27 boys). HI and C completed a weekly 3 hour physical education (PE) session. Before and after a 10-week period, the two groups performed the European physical fitness test battery (EUROFIT). During these 10 weeks HI spent one hour out of three at a specific PE session. These specific sessions consisted of short intermittent exercises (10 seconds) at 100 to 120% of maximal aerobic speed. They showed a significant influence on standing broad jump (2.9 %, P<0.05, F=4.85), 20 meter shuttle run (3.8%, p0.001, F=23.21) and on the maximal distance covered over 7 min (7.6 %, P< 0.001, F= 14.48). For C there was no improvement in EUROFIT performances. It was concluded that training at high intensity improves not only children's aerobic fitness but also performance of standing broad jump. Well-monitored, adequate intensive training is necessary for a more desirable functional development

Comparison of maximal aerobic speed as assessed with laboratory and field measurements in moderately trained subjects.

International audienceIn order to compare the Maximal Aerobic Speed (MAS) evaluated with different methods, eleven male physical education students (22.2 +/- 3.0 years) were submitted to a maximal treadmill protocol and to the Université de Montréal Track Test (UMTT). Four methods were used to calculate MAS. After treadmill measurement of VO2max, MAS was calculated (MAS_calc) by the following formula: MAS_calc = (VO2max - 0.083)/C, where VO2max is the maximal oxygen uptake (ml.kg-1.s-1) and C the energy cost of running (ml.kg-1.m-1). The extrapolated MAS (MAS_ex) was obtained from the measured VO2max and by extrapolation of the VO2 versus speed relationship. The MAS for treadmill measurement (MAS_tr) and for UMTT (MAS_UMTT) were the velocities at the last completed stages. The average MAS_calc (4.71 +/- 0.48 m.s-1), MAS_ex (4.62 +/- 0.48 m.s-1), MAS-tr (4.75 +/- 0.57 m.s-1) and MAS_UMTT (4.64 +/- 0.35 m.s-1) were not significantly different and were significantly correlated, between 0.85 (MAS_ex vs MAS_UMTT) and 0.99 (MAS_calc vs MAS_tr), with p < 0.001 in both cases. MAS measurements were significantly correlated to measured VO2max but independent of C

Validity of the Université de Montréal Track Test to assess the velocity associated with peak oxygen uptake for adolescents.

International audienceThe purpose of the study was to test the ability to determine the velocity associated with peak oxygen uptake for adolescents by means of a simple field test, the Université de Montréal Track Test (UMTT). Fifteen adolescents, 13.4 +/- 1.0 years, performed two maximal field tests where oxygen uptake and heart rate were continuously monitored. The first test (graded field test, first stage 8 km.h-1, increment 1.5 km.h-1, duration 3 min) allowed the subjects to reach a steady-state oxygen uptake. Then, the velocity associated with peak oxygen uptake was calculated from the ratio between peak oxygen uptake above resting level to energy cost of running. The calculated velocity was kept as the criterion velocity. For the second test (UMTT, first stage 8 km.h-1; increment 1 km.h-1; duration 2 min), the velocity measured at the last completed stage was retained. The measured peak oxygen uptake for the graded field test (51.8 +/- 6.5 ml.kg-1.min-1) and for the UMTT (51.0 +/- 7.9 ml.kg-1.min-1) were not significantly different. The calculated velocity (12.9 +/- 1.0 km.h-1) and the measured velocity (12.7 +/- 0.9 km.h-1) were not significantly different and were significantly correlated (r = 0.80, p < 0.001). It was concluded that, for adolescents, the velocity measured at the last completed stage of the UMTT allows a valid estimation of the velocity associated with peak oxygen uptake