RESUMEN
The effects of physical exercise stress on the endocannabinoid system in humans are almost unexplored. In this prospective study, we investigated in a crossover design and under field conditions at different altitudes the effects of physical exercise on the endocannabinoid system (ECS) in 12 trained healthy volunteers. For determination of alterations on the ECS three different protocols were analyzed: Protocol A (physical exercise at lower altitude) involved strenuous hiking below 2,100 m, whereas Protocol B (physical exercise by active ascent to high altitude) involved hiking up to 3,196 m, an accommodation at the cottage and a descent the next day. Protocol C (passive ascent) included a helicopter ascent to 3,196 m, an overnight stay at this altitude and a flight back to the base camp the following day. The cumulative hiked altitude in Protocol A and B was comparable (~1,650 m). The blood EC concentrations of anandamide increased significantly in Protocol A/B from baseline (T0) 0.12 ± 0.01/0.16 ± 0.02 (mean ± SEM) to 0.27 ± 0.02/0.42 ± 0.02 after exercise (T1) (p < 0.05). Anandamide levels in Protocol C remained stable at 0.20 ± 0.02. We conclude that the ECS is activated upon strenuous exercise whereas the combination with hypoxic stress further increases its activity. The reduced partial pressure of oxygen at high altitude alone did not affect this system. In summary, physical exercise activates the endocannabinoid system, whereas the combination with high altitude enhances this activation. This discloses new perspectives to adaptation mechanisms to physical exercise.
Asunto(s)
Altitud , Ácidos Araquidónicos/sangre , Moduladores de Receptores de Cannabinoides/sangre , Endocannabinoides , Ejercicio Físico/fisiología , Resistencia Física/fisiología , Esfuerzo Físico/fisiología , Alcamidas Poliinsaturadas/sangre , Adaptación Fisiológica/fisiología , Humanos , Masculino , Adulto JovenRESUMEN
The objective of this study was to examine microvascular perfusion during hypobaric hypoxia and physical exercise. We used orthogonal polarization spectral imaging for the non-invasive visualization and assessment of the sublingual mucosal microcirculation in twelve healthy altitude acclimatized mountaineers. Red blood cell velocity (RCV), microvascular diameter (Dia), functional capillary density (FCD) and the number of rolling leukocytes were studied at baseline and after (I) a climb to an altitude of 3196 m, (II) a passive ascent to the same altitude by helicopter and (III) an exercise program at an altitude below 2100 m in the European Alps. Exposure to high altitude and exercise resulted in an increased heart rate (Trial I: 64 (54-66) vs. 95 (84-100); median (interquartile range); P<0.05) and decreased oxygen saturation (Trial I: 98 (98-99) vs. 90 (88-92); P<0.05). However, RCV, Dia and FCD did not change significantly. Furthermore, no enhanced rolling of leukocytes in postcapillary venules could be observed (Trial I: 6.2 (4.4-6.8) vs. 7.8 (4.3-6.7)). In the pooled data of all three trials of this study we could show a significant positive correlation between oxygen saturation and red blood cell velocity (r = 0.25; P = 0.02). These results indicate that orthogonal polarization spectral imaging can be a useful tool for the microcirculatory assessment of man under hypoxic conditions. We could show that in trained, acclimatized subjects microvascular perfusion is well maintained during hypobaric hypoxia at an altitude of 3196 m and no evidence for an increased postcapillary leukocyte adhesion was seen.
Asunto(s)
Altitud , Microcirculación , Microscopía de Polarización/métodos , Montañismo , Aclimatación/fisiología , Adulto , Capilares/citología , Capilares/fisiología , Eritrocitos/fisiología , Humanos , Hipoxia/fisiopatología , Leucocitos/fisiología , Masculino , Suelo de la Boca/irrigación sanguínea , Suelo de la Boca/fisiología , Oxígeno/sangre , Perfusión , Flujo Sanguíneo Regional , Vénulas/citología , Vénulas/fisiología , Adulto JovenRESUMEN
BACKGROUND: Retention of mouth-to-mouth, mouth-to-mask and mouth-to-face shield ventilation techniques is poorly understood. METHODS: A prospective randomised clinical trial was undertaken in January 2004 in 70 candidates randomly assigned to training in mouth-to-mouth, mouth-to-mask or mouth-to-face shield ventilation. Each candidate was trained for 10 min, after which tidal volume, respiratory rate, minute volume, peak airway pressure and the presence or absence of stomach inflation were measured. 58 subjects were reassessed 1 year later and study parameters were recorded again. Data were analysed with ANOVA, chi(2) and McNemar tests. RESULTS: Tidal volume, minute volume, peak airway pressure, ventilation rate and stomach inflation rate increased significantly at reassessment with all ventilation techniques compared with the initial assessment. However, at reassessment, mean (SD) tidal volume (960 (446) vs 1008 (366) vs 1402 (302) ml; p<0.05), minute volume (12 (5) vs 13 (7) vs 18 (3) l/min; p<0.05), peak airway pressure (14 (8) vs 17 (13) vs 25 (8) cm H(2)O; p<0.05) and stomach inflation rate (63% vs 58% vs 100%; p<0.05) were significantly lower with mouth-to-mask and mouth-to-face shield ventilation than with mouth-to-mouth ventilation. The ventilation rate at reassessment did not differ significantly between the ventilation techniques. CONCLUSIONS: One year after a single episode of ventilation training, lay persons tended to hyperventilate; however, the degree of hyperventilation and resulting stomach inflation were lower when a mouth-to-mask or a face shield device was employed. Regular training is therefore required to retain ventilation skills; retention of skills may be better with ventilation devices.
Asunto(s)
Reanimación Cardiopulmonar/educación , Retención en Psicología , Reanimación Cardiopulmonar/instrumentación , Reanimación Cardiopulmonar/métodos , Servicios Médicos de Urgencia , Femenino , Humanos , Máscaras Laríngeas , Masculino , Estudios ProspectivosRESUMEN
Emergency medicine is characterized by rapid decision making to help patients in life-threatening situations. Teaching these skills requires a high level of interaction between medical students and the lecturer. We designed, implemented, and evaluated a generic computer-based training (CBT) system to provide a more active way of learning emergency medicine. The content of the training program is adapted to the knowledge of third year medical students and is focused on basic skills and real-world problems. The teacher presents the case with authentic video sequences and slides. The cases are classified into four groups: heart (e.g., myocardial infarction), respiration (e.g., asthma bronchiale), trauma (e.g., car accident), and loss of consciousness (e.g., coma). Within a realistic time frame, the students have to answer free text and multiple choice questions on a work-station. All answers given by the students are processed anonymously by the CBT system via a central server and displayed on a large video screen, thus enabling a detailed discussion without intimidation of individual students. This interactive technique allows for immediate feedback from the lecturer based on the specific knowledge of his group and his own experience. The IT concept, which is scalable to many subjects, is based on state of the art internet technology and therefore suitable for teleteaching. A major design objective for the program was a self-explaining and robust user interface. The system has been in routine use since 1998. We designed an evaluation form consisting of 21 items focused on subjective rating of learning success, acceptance of CBT, and technical feasibility. We analyzed forms from 138 students and found high scores for acceptance and learning success (median 5 on a 6-point scale). user problems with the program were denied (median 1 on a 6-point scale). Computer-based training with Internet technology can provide a successful method for interactive teaching of emergency medicine and is well accepted by students.