Hedenstierna G
Department of Clinical Physiology, Huddinge University Hospital, Sweden.
Eur J Anaesthesiol. 1988 Jul;5(4):221-31.
This review describes the distribution of ventilation and blood flow in the anaesthetized subject, during spontaneous breathing and after muscle paralysis. Within minutes after induction of anaesthesia, the diaphragm is shifted cranially (supine position), functional residual capacity is reduced and collapse of dependent lung regions can be seen by means of computed tomography. These changes occur whether anaesthesia is intravenous (barbiturate) or inhalational (halothane) and whether ventilation is spontaneous or mechanical. Ventilation is subsequently reduced in dependent lung regions, whereas blood flow is preferentially distributed to the lower lung regions. This causes a ventilation/perfusion mismatch, the hall-mark of which is shunt. Additional factors such as airway closure and release of hypoxic pulmonary vasoconstriction may contribute to the gas exchange disturbance. The major features of the lung function impairment are already present during spontaneous breathing in the anaesthetized subject, and muscle paralysis adds only little to the disturbance.
本综述描述了麻醉状态下受试者在自主呼吸和肌肉麻痹后通气与血流的分布情况。麻醉诱导后数分钟内，膈肌向头侧移位（仰卧位），功能残气量降低，通过计算机断层扫描可观察到下垂肺区萎陷。无论麻醉是静脉注射（巴比妥类）还是吸入（氟烷），也无论通气是自主的还是机械的，这些变化都会发生。随后，下垂肺区的通气减少，而血流则优先分布于下肺区。这会导致通气/灌注不匹配，其特征为分流。诸如气道闭合和缺氧性肺血管收缩的解除等其他因素可能会导致气体交换障碍。肺功能损害的主要特征在麻醉受试者自主呼吸时就已存在，肌肉麻痹只会使这种障碍稍有加重。
