Impairments in Gas Exchange and Mechanical Properties of the Lung in Acute Cerebral Circulatory Disorders

Abstract

Objective: to study impairments in gas exchange and mechanical properties of the lung in relation to the pattern of a brain lesion in acute cerebral circulatory disorders (ACCD). Subjects and methods. Gas exchange (oxygenation index (PaO2/FiO2) and the degree of intrapulmonary blood shunting (Qs/Qt)), the mechanical properties of the lung (mean airway pressure (Р^^), airway resistance (Raw), static thoracopulmonary compliance (Cltst)), intracranial pressure (ICP) were studied and brain spiral computed tomography (SCT) was conducted on days 1, 3, 5, and 7 of the acute phase of ACCD in 18 patients. Results. Pmean increased in both groups on days 3 to 7, rose from day 5 in the presence of hemorrhagic stroke. Cltst was decreased and Raw was increased. From day 3 of hemorrhagic stroke, Cltst significantly became lower and Raw was higher. PaO2/FiO2 decreased from day 5, more in hemorrhagic stroke and Qs/Qt increased. ICP persisted in the upper normal range in ischemic stroke and rose up to 27.5±2.7 mm Hg in hemorrhagic stroke. A strong inverse correlation was found between ICP and PaO2/FiO2. SCT revealed dislocation in 13 patients. Conclusion. Gas exchange and the mechanical properties of the lung are impaired in acute cerebral circulatory disorders. The causes of this are multiple, but one of them is dysfunction of the stem structures of the brain due to its dislocation in the presence of high intracranial pressure. In hemorrhagic stroke, the impairments in gas exchange and mechanical properties of the lung are more marked and develop earlier than in ischemic stroke. Key words: acute cerebral circulatory disorder, respiratory failure, gas exchange, mechanical properties of the lung, intracranial pressure.