Comparative analysis of dose distribution to critical organs in radiation therapy of left breast cancer with respiratory synchronization

Relevance: Breast cancer is one of the most common oncological diseases. Today, it leads among female cancers. Patients with left breast cancer undergoing radiation therapy have a considerable risk of developing cardiovascular diseases caused by ionizing radiation. Various methods are introduced to reduce the radiation load to critical organs to ensure compliance with the main radiation therapy principle. One of these methods is radiation therapy with synchronized breathing, including deep inspiration breath-hold (DIBH). DIBH can significantly reduce the dose load to the heart and the left lung. The study aimed to compare the radiation load to the heart and the left lung during radiation therapy for left breast cancer with free breathing and respiratory synchronization. Results: During radiation therapy with synchronized breathing, the average radiation load to the heart is 1.7 times lower and to the left lung – 1.26 times lower compared to radiation therapy with free breathing. Conclusion: The study results confirm that respiratory synchronization in radiation therapy for left breast cancer reduces the dose to the heart and the left lung.

Comparative analysis of dose distribution to critical organs in radiation therapy of left breast cancer with respiratory synchronization

Relevance: Breast cancer is one of the most common oncological diseases. Today, it leads among female cancers. Patients with left breast cancer undergoing radiation therapy have a considerable risk of developing cardiovascular diseases caused by ionizing radiation. Various methods are introduced to reduce the radiation load to critical organs to ensure compliance with the main radiation therapy principle. One of these methods is radiation therapy with synchronized breathing, including deep inspiration breath hold (DIBH). DIBH can significantly reduce the dose load to the heart and the left lung. The study aimed to compare the radiation load to the heart and the left lung during radiation therapy for left breast cancer with free breathing and respiratory synchronization. Results: During radiation therapy with synchronized breathing, the average radiation load to the heart is 1.7 times lower and to the left lung – 1.26 times lower compared to radiation therapy with free breathing. Conclusion: The study results confirm that respiratory synchronization in radiation therapy for left breast cancer reduces the dose to the heart and the left lung.

Evidence of Autonomic Dysfunction in Patients with Relapsing-Remitting Multiple Sclerosis: Heart Rate Variability and Cardiovascular Parameters

This study was aimed at evaluation of autonomic dysfunction in patients with multiple sclerosis (MS) by means of time- and frequency-domain parameters of heart rate variability (HRV) and conventional cardiovascular tests (deep breathing (DB) and active orthostatic test (AOT)). The study group enrolled 32 patients with the relapsing-remitting MS (17 m, 15 f, aged 29 ± 4.9 years, disease duration 4.2 ± 2.7 years, EDSS scores less than 3.0 and 26 subjects in good health (HC, 15 m, 11 f, aged 30.1 ± 2.7 years). In the MS group, at rest the variability of heart rate was decreased in comparison to the HC group seen by time- (SDNN, RMSSD, pNN50, CV, p < 0.01) and frequency-domain (TP, HF, LF, p < 0.05) parameters, what was indicative of the general decrease of the autonomic neurogenic control of the heart rate, both sympathetic and parasympathetic. The functional tests (DB and AOT) showed reduced cardiovascular reactivity in the MS group. Additionally, the cardio-respiratory synchronization was impaired in the MS group at rest and DB. The severity of HRV deficit in the MS group correlated with the activity of MS. In conclusion, the comprehensive assessment of time- and frequency-domain HRV parameters studied with functional tests provides better insight to understanding autonomic dysfunction in subjects with relapsing-remitting MS.

Study of cardiovascular and respiratory synchronization in different types of breathing

Актуальность. В работе обоснован диагностический алгоритм, позволяющий объективно устанавливать критерии синхронизации в регуляции кардио-респираторной системы, обеспечивающей адекватный уровень адаптации организма при умеренных внешних воздействиях. Целью данной работы явилось изучение возможных параметров сопряжённости сердечного, сосудистого и дыхательного ритмов при выполнении функциональных проб: пробы с фиксированной частотой дыхания и ступенчато-возрастающей умеренной физической нагрузкой. Методы. Для реализации диагностического алгоритма был использован действующий макет комплекса «Спироартериокардиоритмограф-01», адаптированный под совместное использование с велоэргометром. Подобный подход обеспечивает объективный мониторинг сердечно-дыхательного синхронизма в динамике разнообразных внешних воздействий на организм. Результаты. На основе прямых динамических показателей обоснован алгоритм расчета отношения минутного объема кровообращения и минутного объема дыхания, отражающий степень функционального баланса сердечно-дыхательного гомеостаза. Выводы. Многопараметровость, быстрота и неинвазивность исследований обеспечат востребованность данной методологии в разнообразных направлениях предиктивной диагностики. The authors justified a diagnostic algorithm for establishing objective criteria of cardiovascular and respiratory synchronization, which provides an adequate adaptive response to different external factors. For evaluation of the diagnostic algorithm, the Spiroarteriokardioritmograf-01 complex compatible with a bicycle ergometer was used. This approach provides objective monitoring of cardiovascular and respiratory synchronism under the influence of various external factors. Multiparameter, fast, and non-invasive features of these studies will cover a demand for this method in predictive diagnostics. Based on direct dynamic indicators an algorithm was substantiated for calculation of the blood flow minute volume to respiratory minute volume ratio, which reflects the degree of functional balance in the cardiovascular and respiratory homeostasis.

Broadly tuned and respiration-independent inhibition in the olfactory bulb of awake mice

Olfactory representations are shaped by both brain state and respiration; however, the interaction and circuit substrates of these influences are poorly understood. Granule cells (GCs) in the main olfactory bulb (MOB) are presumed to sculpt activity that reaches the olfactory cortex via inhibition of mitral/tufted cells (MTs). GCs may potentially sparsen ensemble activity by facilitating lateral inhibition among MTs, and/or they may enforce temporally-precise activity locked to breathing. Yet, the selectivity and temporal structure of GC activity during wakefulness are unknown. We recorded GCs in the MOB of anesthetized and awake mice and reveal pronounced state-dependent features of odor coding and temporal patterning. Under anesthesia, GCs exhibit sparse activity and are strongly and synchronously coupled to the respiratory cycle. Upon waking, GCs desynchronize, broaden their odor responses, and typically fire without regard for the respiratory rhythm. Thus during wakefulness, GCs exhibit stronger odor responses with less temporal structure. Based on these observations, we propose that during wakefulness GCs likely predominantly shape MT odor responses through broadened lateral interactions rather than respiratory synchronization.