颅内高压对肺动静脉分流影响的实验研究

EXPERIMENTAL STUDY IN THE EFFECT OF RAISED INTRACRANIAL PRESSURE ON PULMONARY SHUNT

作者用9条狗,研究颅内高压对肺动静脉分流(Qs/Qt)的影响。在硬膜外置胶囊注入液体升高颅内压(ICP)至100和150mmHg。在ICP 100mmHg阶段,Qs/Qt变化不明显。当ICP 150mmHg时,Qs/Qt由10.0±3.1％上升到16.0±5.6％(P<0.01),同时动脉血氧分压下降,肺动脉压和肺动脉楔压升高。Qs/tQ值的增加与氧分压下降以及肺含水量相关显著,Qs/Qt增加的原因,与肺动静脉吻合枝开放,肺动脉不均匀收缩及通气/血流比值失调有关。提出Qs/Qt值增加可能是神经源性肺水肿的发病机理之一。并指出Qs/Qt增加是颅内高压时低氧血症的主要原因。测定Qs/Qt对判断颅内高压时肺功能损害程度较氧分压更具敏感性和可靠性。

The effect of raised intracranial pressure (ICP) on pulmonary shunt (Qs/Qt) was studied in 9 mongrel dogs. ICP was elevated to 100 mmHg and 150 mmHg by means of injection of water into an elastic bag in the epidural space. No change was noticed in Qs/Qt while ICP was at the level of 100 mmHg for 30 min. However, when ICP was raised to 150 mmHg for the same time, the Qs/Qt increased from 10.0±3.1% to 16.0±5.6% (P<0.01), PaO_2 decreased, and pulmonary arterial pressure as well as pulmonary arterial wedge pressure increased. The Qs/Qt increase correlated negatively with PaO_2 and positively with the water fraction of the lungs. Some factors were related to Qs/Qt increase, such as opening of pulmonary arterial constriction, and abnor mality of ventilation to blood flow ratio in alveoli. Qs/Qt increase may also cause hypoxia and neurogenic pulmonary edema. We conclude that measurement of Qs/Qt is of help to judge the degree of pulmonary insufficiency resulted from raised ICP.