Resistance training improves cardiac function and cardiovascular autonomic control in doxorubicin-induced cardiotoxicity.

Doxorubicin (DOX) is an anticancer chemotherapy drug that is widely used in clinical practice. It is well documented that DOX impairs baroreflex responsiveness and left ventricular function and enhances sympathetic activity, cardiac sympathetic afferent reflexes and oxidative stress, which contribute to hemodynamic deterioration. Because resistance training (RT)-induced cardioprotection has been observed in other animal models, the objective of this study was to assess the effects of RT during DOX treatment on hemodynamics, arterial baroreflex, cardiac autonomic tone, left ventricular function and oxidative stress in rats with DOX-induced cardiotoxicity. Male Wistar rats were submitted to a RT protocol (3 sets of 10 repetitions, 40% of one-repetition maximum (1RM) of intensity, 3 times per week, for 8 weeks). The rats were separated into 3 groups: sedentary control, DOX sedentary (2.5 mg/kg of DOX intraperitoneal injection, once a week, for 6 weeks) and DOX + RT. After training or time control, the animals were anesthetized and 2 catheters were implanted for hemodynamic, arterial baroreflex and cardiac autonomic tone. Another group of animals was used to evaluate left ventricular function. We found that RT in DOX-treated rats decreased diastolic arterial pressure, heart rate, sympathetic tone and oxidative stress. In addition, RT increased arterial baroreflex sensitivity, vagal tone and left ventricular developed pressure in rats with DOX-induced cardiotoxicity. In summary, RT is a useful non-pharmacological strategy to attenuate DOX-induced cardiotoxicity.

Accuracy of optoelectronic plethysmography in childhood exercise-induced asthma.

OBJECTIVE: To assess the variations of end-expiratory volume of chest wall (EEVcw) measured by optoelectronic plethysmography (OEP) as a diagnostic tool in exercise-induced asthma (EIA) among asthmatic preschool children. METHODS: Forty children diagnosed with asthma were included in the study. Spirometry was used as a gold standard test for comparison with OEP. A 10% decline in forced expiratory volume in 1 second was considered positive for EIA. OEP was performed with 8 cameras at a frequency of 60 Hz and 89 markers were placed on the thoraco-abdominal surface of participants. Following bronchoprovocation testing on a treadmill, series of OEP and spirometry were conducted between 5 and 30 minutes after exercise. To obtain the ideal cut-off point, a receiver operating characteristic (ROC) curve was constructed for the largest EEVcw. The highest Youden index was used as criteria to obtain the cut-off point with the best sensitivity and specificity. RESULTS: Of the 40 children studied, 16 had EIA. According to the ROC curve, the cut-off point of 0.185% for EEWcw provided mean sensitivity (95% confidence interval) of 93.75% (0.69-0.99), for a specificity of 83.33% (0.63-0.95), when using the largest increase in the period of 5-30 minutes post-exercise. The low area of the ROC was 0.93 (0.85-1.00) for p < 0.001. CONCLUSION: OEP can be accurately used to replace spirometry in asthmatic children unable to adequately execute the required manoeuvres.

Influência dos corticosteroides inalatórios nas pressões respiratórias máximas de crianças escolares asmáticas / Influence of inhaled corticosteroids in the maximal respiratory pressure in asthmatic school children

INTRODUÇÃO: O corticosteroide inalatório (CI) é o principal medicamento utilizado no tratamento profilático e de manuten­cão da asma. Graças à superdosagem ou ao uso prolongado dos CIs podem surgir efeitos colaterais como a redução do crescimento ósseo, supressão adrenal e miopatia. OBJETIVOS: Avaliar a influência dos corticosteroides inalatórios nas pressões inspiratórias (PImax) e expiratórias (PEmax) máximas de crianças escolares asmáticas. MATERIAIS E MÉTODOS: Estudo transversal, observacional, que incluiu 60 crianças entre 6 e 12 anos de idade divididas em três grupos: controle (CG), asma (GA) e crianças com asma que faziam uso de CI por pelo menos três meses (GA+CI). As avaliações das pressões respiratórias foram realizadas em três dias diferentes com intervalo de 12 dias entre elas. RESULTADOS: A média ± DP da PImax no terceiro dia foi - (65,4 ± 21,9), - (74,9 ± 19,5) e - (80,7 ± 21,5) cmH2O para os grupos GA, GA+CI e GC, respectivamente. A PImax foi menor no GA em relação ao GC (p < 0,05). A média ± DP da PEmax no terceiro dia foi 52,7 ± 14,8; 61,7 ± 17,4; e 75,6 ± 18,4 cmH2O para os grupos GA, GA+CI e GC, respectivamente. A PEmax foi maior no GC em relação ao GA (p < 0,05). A PEmax foi maior no GC em relação ao GA+CI (p < 0,05). CONCLUSÕES: Os resultados sugerem que os CIs promovem maior controle da hiperinsuflação pulmonar com aumento da PImax nas crianças com asma, porém promovem também redução da PEmax, provavelmente em razão do efeito do CI sobre as fibras musculares tipo II.

INTRODUCTION: The inhaled corticosteroid (IC) is the mean therapy used for the preventive and maintenance treatment of asthma. Overdose or prolonged use of IC can cause some collateral effects as remission in bone growth, adrenal suppression and myopathy. OBJECTIVES: To evaluate the influence of inhaled corticosteroids in the inspiratory and expiratory strength in asthmatic school children. MATERIALS AND METHODS: A cross-sectional, observational study, that included 60 children between 6 to 12 years divided into three groups: control (CG), asthma (AG) and children whose used IC for at least three months (AG+IC). The maximal inspiratory pressure (MIP) and maximal expiratory pressure (MEP) were measured in 3 different days with 12 days between them. RESULTS: The mean ± SD of MIP in the third day was - (65.4 ± 21.9), - (74.9 ± 19.5) and - (80.7 ± 21.5) cmH2O to the AG, AG+IC and CG, respectively. The MIP in the AG was lesser than in the CG (p < 0.05). The mean ± SD of MEP in the third day was 52.7 ± 14.8; 61.7 ± 17.4; and 75.6 ± 18.4 cmH2O to the AG, AG+IC and CG, respectively. The MEP was superior in the CG than in the AG (p < 0.05). The MEP was superior in the CG than the AG+CI (p < 0.05). CONCLUSIONS:The results suggest that IC promotes a major control of pulmonary hiperinflation with the increase of MIP in asthmatic children, but decrease the MEP probably by the effect in the type II muscles fibers.