Voelckel W G, Lurie K G, Zielinski T, McKnite S, Plaisance P, Wenzel V, Lindner K H
Cardiac Arrhythmia Center, Cardiovascular Division, Department of Medicine, University of Minnesota, Minneapolis 55455, USA.
Anesth Analg. 2001 Apr;92(4):967-74. doi: 10.1097/00000539-200104000-00032.
The use of an inspiratory impedance threshold valve (ITV) during active compression-decompression (ACD) cardiopulmonary resuscitation (CPR) improves perfusion pressures, and vital organ blood flow. We evaluated the effects of positive end-expiratory pressure (PEEP) on gas exchange, and coronary perfusion pressure gradients during ACD + ITV CPR in a porcine cardiac arrest model. All animals received pure oxygen intermittent positive pressure ventilation (IPPV) at a 5:1 compression-ventilation ratio during ACD + ITV CPR. After 8 min, pigs were randomized to further IPPV alone (n = 8), or IPPV with increasing levels of PEEP (n = 8) of 2.5, 5.0, 7.5, and 10 cm H(2)O for 4 consecutive min each, respectively. Mean +/- SEM arterial oxygen partial pressure decreased in the IPPV group from 150 +/- 30 at baseline after 8 min of CPR to 110 +/- 25 torr at 24 min, but increased in the PEEP group from 115 +/- 15 to 170 +/- 25 torr with increasing levels of PEEP (P <0.02 for comparisons within groups). Mean +/- SEM diastolic aortic minus diastolic left ventricular pressure gradient was significantly (P < 0.001) higher after the administration of PEEP (24 +/- 0 vs 17 +/- 1 mm Hg with 5 cm H(2)O of PEEP, and 26 +/- 0 vs 17 +/- 1 mm Hg with 10 cm H(2)O of PEEP), whereas the diastolic aortic minus right atrial pressure gradient (coronary perfusion pressure) was comparable between groups. Furthermore, systolic aortic pressures were significantly (P < 0.05) higher with 10 cm H(2)O of PEEP when compared with IPPV alone (68 +/- 0 vs 59 +/- 2 mm Hg). In conclusion, when CPR was performed with devices designed to improve venous return to the chest, increasing PEEP levels improved oxygenation. Moreover, PEEP significantly increased the diastolic aortic minus left ventricular gradient and did not affect the decompression phase aortic minus right atrial pressure gradient. These data suggest that PEEP reduces alveolar collapse during ACD + ITV CPR, thus leading to an increase in indirect myocardial compression.
Inspiratory impedance during active compression-decompression cardiopulmonary resuscitation improves perfusion pressures, and vital organ blood flow during cardiac arrest. Increasing levels of positive end-expiratory pressure during performance of active compression-decompression cardiopulmonary resuscitation with an inspiratory impedance valve improves oxygenation, and increases the diastolic aortic-left ventricular pressure gradient and systolic arterial blood pressure.
在主动按压-减压（ACD）心肺复苏（CPR）过程中使用吸气阻抗阈值阀（ITV）可提高灌注压力和重要器官的血流。我们在猪心脏骤停模型中评估了呼气末正压（PEEP）对ACD + ITV CPR期间气体交换和冠状动脉灌注压力梯度的影响。在ACD + ITV CPR期间，所有动物均以5:1的按压-通气比接受纯氧间歇正压通气（IPPV）。8分钟后，猪被随机分为仅进一步接受IPPV组（n = 8）或接受逐渐增加水平PEEP的IPPV组（n = 8），PEEP水平分别为2.5、5.0、7.5和10 cmH₂O，每组各持续4分钟。IPPV组的平均±标准误动脉血氧分压在CPR 8分钟后的基线水平为150±30，到24分钟时降至110±25 torr，但PEEP组随着PEEP水平的增加从115±15升至170±25 torr（组内比较P <0.02）。给予PEEP后，平均±标准误舒张期主动脉减去舒张期左心室压力梯度显著更高（PEEP为5 cmH₂O时为24±0对比17±1 mmHg，PEEP为10 cmH₂O时为26±0对比17±1 mmHg，P <0.001），而舒张期主动脉减去右心房压力梯度（冠状动脉灌注压力）在各组之间相当。此外，与仅IPPV相比，PEEP为1 cmH₂O时收缩期主动脉压显著更高（68±0对比59±2 mmHg，P <0.05）。总之，如果使用旨在改善静脉回流至胸部的装置进行CPR，增加PEEP水平可改善氧合。此外，PEEP显著增加舒张期主动脉减去左心室梯度，且不影响减压期主动脉减去右心房压力梯度。这些数据表明，PEEP可减少ACD + ITV CPR期间的肺泡塌陷，从而导致间接心肌压迫增加。
主动按压-减压心肺复苏期间的吸气阻抗可提高心脏骤停期间的灌注压力和重要器官血流。在使用吸气阻抗阀进行主动按压-减压心肺复苏时增加呼气末正压水平可改善氧合，并增加舒张期主动脉-左心室压力梯度和收缩期动脉血压。
