Fujian Shengli Clinical Medical College, Fujian Medical University, Fuzhou, China.
Department of Critical Care Medicine, Fujian Provincial Hospital, Fuzhou, China.
BMC Neurosci. 2021 Nov 25;22(1):72. doi: 10.1186/s12868-021-00674-9.
To evaluate the impact of positive end-expiratory pressure (PEEP) on intracranial pressure (ICP) in animals with different respiratory mechanics, baseline ICP and volume status.
A total of 50 male adult Bama miniature pigs were involved in four different protocols (n = 20, 12, 12, and 6, respectively). Under the monitoring of ICP, brain tissue oxygen tension and hemodynamical parameters, PEEP was applied in increments of 5 cm HO from 5 to 25 cm HO. Measurements were taken in pigs with normal ICP and normovolemia (Series I), or with intracranial hypertension (via inflating intracranial balloon catheter) and normovolemia (Series II), or with intracranial hypertension and hypovolemia (via exsanguination) (Series III). Pigs randomized to the control group received only hydrochloride instillation while the intervention group received additional chest wall strapping. Common carotid arterial blood flow before and after exsanguination at each PEEP level was measured in pigs with intracranial hypertension and chest wall strapping (Series IV).
ICP was elevated by increased PEEP in both normal ICP and intracranial hypertension conditions in animals with normal blood volume, while resulted in decreased ICP with PEEP increments in animals with hypovolemia. Increasing PEEP resulted in a decrease in brain tissue oxygen tension in both normovolemic and hypovolemic conditions. The impacts of PEEP on hemodynamical parameters, ICP and brain tissue oxygen tension became more evident with increased chest wall elastance. Compare to normovolemic condition, common carotid arterial blood flow was further lowered when PEEP was raised in the condition of hypovolemia.
The impacts of PEEP on ICP and cerebral oxygenation are determined by both volume status and respiratory mechanics. Potential conditions that may increase chest wall elastance should also be ruled out to avoid the deleterious effects of PEEP.
为了评估不同呼吸力学和基础颅内压（ICP）及容量状态的动物中，呼气末正压（PEEP）对 ICP 的影响。
共纳入 50 只雄性成年巴马小型猪，分别进行 4 种不同方案（n = 20、12、12 和 6）。在 ICP、脑组织氧张力和血流动力学参数监测下，从 5 至 25cmH2O 逐渐增加 PEEP。在 ICP 和脑血容量正常的猪（系列 I）或颅内高压（通过颅内球囊导管充气）和脑血容量正常的猪（系列 II）或颅内高压和低血容量（通过放血）（系列 III）中进行测量。随机分配到对照组的猪仅接受盐酸灌注，而干预组则接受额外的胸壁捆扎。在颅内高压和胸壁捆扎的猪（系列 IV）中，在每个 PEEP 水平下，通过放血前后测量颈总动脉血流来评估 PEEP 的影响。
在正常血容量动物的正常 ICP 和颅内高压状态下，增加 PEEP 会导致 ICP 升高，而在低血容量动物中，增加 PEEP 会导致 ICP 降低。在正常血容量和低血容量状态下，增加 PEEP 会导致脑组织氧张力降低。在胸廓顺应性增加的情况下，PEEP 对血流动力学参数、ICP 和脑组织氧张力的影响变得更加明显。与正常血容量状态相比，在低血容量状态下，当 PEEP 升高时，颈总动脉血流进一步降低。
PEEP 对 ICP 和脑氧合的影响取决于容量状态和呼吸力学。还应排除可能增加胸壁顺应性的潜在条件，以避免 PEEP 的有害影响。
