К вопросу совершенствования технологии управления процессами воздухораспределения и газовыделения на выемочных участках

Розглянуто процес розвитку технологічних схем провітрювання та дегазації виймальних ділянок вугільних шахт. Показане, що вакуумування і відвід по трубопроводу притоків газоповітряної суміші з верхньої частини лави за межі виймальної дільниці відкриває можливість впливати на аеродинамічний процес одночасно у двох напрямках – у керуванні газовиділенням і повітрерозподілом. Вплив такого впливу розглянуте в умовах основних застосовуваних схем провітрювання.The process of technological schemes of ventilation and drainage excavation sites of coal mines. Shown that the evacuation and removal via tributaries of gas-air mixture from the top of the long wall beyond excavation site provides an opportunity to influence the aerodynamic processes in two directions - in the management of any gas and air distribution. The effect of such exposure is considered in terms of the basic circuits used airing

Different CT perfusion algorithms in the detection of delayed cerebral ischemia after aneurysmal subarachnoid hemorrhage

Introduction: Tracer delay-sensitive perfusion algorithms in CT perfusion (CTP) result in an overestimation of the extent of ischemia in thromboembolic stroke. In diagnosing delayed cerebral ischemia (DCI) after aneurysmal subarachnoid hemorrhage (aSAH), delayed arrival of contrast due to vasospasm may also overestimate the extent of ischemia. We investigated the diagnostic accuracy of tracer delay-sensitive and tracer delay-insensitive algorithms for detecting DCI. Methods: From a prospectively collected series of aSAH patients admitted between 2007–2011, we included patients with any clinical deterioration other than rebleeding within 21 days after SAH who underwent NCCT/CTP/CTA imaging. Causes of clinical deterioration were categorized into DCI and no DCI. CTP maps were calculated with tracer delay-sensitive and tracer delay-insensitive algorithms and were visually assessed for the presence of perfusion deficits by two independent observers with different levels of experience. The diagnostic value of both algorithms was calculated for both observers. Results: Seventy-one patients were included. For the experienced observer, the positive predictive values (PPVs) were 0.67 for the delay-sensitive and 0.66 for the delay-insensitive algorithm, and the negative predictive values (NPVs) were 0.73 and 0.74. For the less experienced observer, PPVs were 0.60 for both algorithms, and NPVs were 0.66 for the delay-sensitive and 0.63 for the delay-insensitive algorithm. Conclusion: Test characteristics are comparable for tracer delay-sensitive and tracer delay-insensitive algorithms for the visual assessment of CTP in diagnosing DCI. This indicates that both algorithms can be used for this purpose

Different CT perfusion algorithms in the detection of delayed cerebral ischemia after aneurysmal subarachnoid hemorrhage

Introduction: Tracer delay-sensitive perfusion algorithms in CT perfusion (CTP) result in an overestimation of the extent of ischemia in thromboembolic stroke. In diagnosing delayed cerebral ischemia (DCI) after aneurysmal subarachnoid hemorrhage (aSAH), delayed arrival of contrast due to vasospasm may also overestimate the extent of ischemia. We investigated the diagnostic accuracy of tracer delay-sensitive and tracer delay-insensitive algorithms for detecting DCI. Methods: From a prospectively collected series of aSAH patients admitted between 2007–2011, we included patients with any clinical deterioration other than rebleeding within 21 days after SAH who underwent NCCT/CTP/CTA imaging. Causes of clinical deterioration were categorized into DCI and no DCI. CTP maps were calculated with tracer delay-sensitive and tracer delay-insensitive algorithms and were visually assessed for the presence of perfusion deficits by two independent observers with different levels of experience. The diagnostic value of both algorithms was calculated for both observers. Results: Seventy-one patients were included. For the experienced observer, the positive predictive values (PPVs) were 0.67 for the delay-sensitive and 0.66 for the delay-insensitive algorithm, and the negative predictive values (NPVs) were 0.73 and 0.74. For the less experienced observer, PPVs were 0.60 for both algorithms, and NPVs were 0.66 for the delay-sensitive and 0.63 for the delay-insensitive algorithm. Conclusion: Test characteristics are comparable for tracer delay-sensitive and tracer delay-insensitive algorithms for the visual assessment of CTP in diagnosing DCI. This indicates that both algorithms can be used for this purpose

Relationship Between Cardiac Dysfunction and Cerebral Perfusion in Patients with Aneurysmal Subarachnoid Hemorrhage

Cardiac dysfunction may occur after aneurysmal subarachnoid hemorrhage (aSAH). Although it is associated with poor outcome, the pathophysiological mechanism of this association remains unclear. We investigated the relationship between cardiac function and cerebral perfusion in patients with aSAH. We studied 72 aSAH patients admitted within 72 h after ictus with echocardiography and cerebral CT perfusion within 24 h after admission. Cardiac dysfunction was defined as myocardial wall motion abnormalities or positive troponin. In patients with and without cardiac dysfunction, we calculated the mean perfusion [cerebral blood flow (CBF) and time-to-peak (TTP)] in standard regions of interest and calculated differences with 95% confidence intervals (95% CI). In 35 patients with cardiac dysfunction minimal CBF was 15.83 mL/100 g/min compared to 18.59 in 37 without (difference of means -2.76; 95% CI -5.43 to -0.09). Maximal TTP was 26.94 s for patients with and 23.10 s for patients without cardiac dysfunction (difference of means 3.84; 95% CI 1.63-6.05). Mean global CBF was 21.71 mL/100 g/min for patients with cardiac dysfunction and 24.67 mL/100 g/min for patients without cardiac dysfunction (-2.96; 95% CI -6.19 to 0.27). Mean global TTP was 25.27 s for patients with cardiac dysfunction and 21.26 for patients without cardiac dysfunction (4.01; 95% CI 1.95-6.07). aSAH patients with cardiac dysfunction have decreased focal and global cerebral perfusion. Further studies should evaluate whether this relation is explained by a direct effect of cardiac dysfunction on cerebral circulation or by an external determinant, such as a hypercatecholaminergic or hypometabolic state, influencing both cardiac function and cerebral perfusio

CT perfusion on admission and cognitive functioning 3 months after aneurysmal subarachnoid haemorrhage

Many survivors of aneurysmal subarachnoid haemorrhage (aSAH) have persistent cognitive deficits. Underlying causes of these deficits have not been elucidated. We aimed to investigate if cerebral perfusion in the acute phase after aSAH measured with CT perfusion (CTP) is associated with cognitive outcome 3 months after aSAH. We included 71 patients admitted to the University Medical Center Utrecht who had CTP performed within 24 h after ictus and neuropsychological examination after 3 months. Perfusion values were measured in predefined regions of interest for cerebral blood flow (CBF), cerebral blood volume (CBV), mean transit time (MTT), and time to peak (TTP). The relationship with global cognitive functioning, as measured with a mean z score of all cognitive tests, was examined by linear regression analyses. Adjustments were made for age, education, method of aneurysm treatment, and presence of non-acute medical complications. TTP was associated with cognitive functioning in the univariable analysis (B = -0.042, 95 % CI -0.076 to -0.008), but not after adjustment for age (B = -0.030, 95 % CI -0.065 to 0.004). For CBF, CBV and MTT no relationship with cognitive functioning was observed. Cerebral perfusion measured with CTP within 24 h after onset of aSAH is not associated with cognitive outcome after 3 months. The lack of an association might be explained by the delay between onset of aSAH and CTP. However, CTP assessment within the first minutes after aSAH is impossible in large series of patients