Moomey C B, Fabian T C, Croce M A, Melton S M, Proctor K G
Department of Surgery, University of Tennessee, Memphis, USA.
J Trauma. 1998 Aug;45(2):283-90. doi: 10.1097/00005373-199808000-00013.
To compare the effects of mechanical ventilation with either positive end-expiratory pressure (PEEP) or partial liquid ventilation (PLV) on cardiopulmonary function after severe pulmonary contusion.
Mongrel pigs (32 +/- 1 kg) were anesthetized, paralyzed, and mechanically ventilated (8-10 mL/kg tidal volume; 12 breaths/min; FiO2 = 0.5). Systemic hemodynamics and pulmonary function were measured for 7 hours after a captive bolt gun delivered a blunt injury to the right chest. After 5 hours, FiO2 was increased to 1.0 and either PEEP (n = 7) in titrated increments to 25 cm H2O or PLV with perflubron (LiquiVent, 30 mL/kg, endotracheal) and no PEEP (n = 7) was administered for 2 hours. Two control groups received injury without treatment (n = 6) or no injury with PLV (n = 3). Fluids were liberalized with PEEP versus PLV (27 +/- 3 vs. 18 +/- 2 mL.kg-1.h-1) to maintain cardiac filling pressures.
Before treatment at 5 hours after injury, physiologic dead space fraction (30 +/- 4%), pulmonary vascular resistance (224 +/- 20% of baseline), and airway resistance (437 +/- 110% of baseline) were all increased (p < 0.05). In addition, PaO2/FiO2 had decreased to 112 +/- 18 mm Hg, compliance was depressed to 11 +/- 1 mL/cm H2O (36 +/- 3% of baseline), and shunt fraction was increased to 22 +/- 4% (all p < 0.05). Blood pressure and cardiac index remained stable relative to baseline, but stroke index and systemic oxygen delivery were depressed by 15 to 30% (both p < 0.05). After 2 hours of treatment with PEEP versus PLV, PO2/FiO2 was higher (427 +/- 20 vs. 263 +/- 37) and dead space ventilation was lower (4 +/- 3 vs. 28 +/- 7%) (both p < 0.05), whereas compliance tended to be higher (26 +/- 2 vs. 20 +/- 2) and shunt fraction tended to be lower (0 +/- 0 vs. 7 +/- 4). With PEEP versus PLV, however, cardiac index, stroke index, and systemic oxygen delivery were 30 to 60% lower (all p < 0.05). Furthermore, although contused lungs showed similar damage with either treatment, the secondary injury in the contralateral lung (as manifested by intra-alveolar hemorrhage) was more severe with PEEP than with PLV.
Both PEEP and PLV improved pulmonary function after severe unilateral pulmonary contusion, but negative hemodynamic and histologic changes were associated with PEEP and not with PLV. These data suggest that PLV is a promising novel ventilatory strategy for unilateral pulmonary contusion that might ameliorate secondary injury in the contralateral uninjured lung.
比较呼气末正压通气（PEEP）与部分液体通气（PLV）对严重肺挫伤后心肺功能的影响。
选用杂种猪（体重32±1 kg），进行麻醉、肌松，并给予机械通气（潮气量8 - 10 mL/kg；呼吸频率12次/分钟；吸入氧浓度FiO2 = 0.5）。用气栓枪对猪右胸进行钝性损伤，伤后7小时监测其全身血流动力学和肺功能。5小时后，将FiO2增至1.0，对7只猪给予递增剂量的PEEP直至25 cm H2O，持续2小时；对另7只猪给予全氟溴烷进行PLV（LiquiVent，30 mL/kg，经气管内给药），不给予PEEP，持续2小时。两个对照组，一组为受伤未治疗（n = 6），另一组为未受伤但给予PLV（n = 3）。给予PEEP组与PLV组的补液量不同（分别为27±3与18±2 mL·kg-1·h-1），以维持心脏充盈压。
受伤后5小时治疗前，生理死腔分数（30±4%）、肺血管阻力（为基线值的224±20%）和气道阻力（为基线值的437±110%）均升高（p < 0.05）。此外，动脉血氧分压与吸入氧浓度之比（PaO2/FiO2）降至112±18 mmHg，肺顺应性降至11±1 mL/cm H2O（为基线值的36±3%），分流分数增至22±4%（均p < 0.05）。血压和心脏指数相对于基线保持稳定，但每搏指数和全身氧输送量降低了15%至30%（均p < 0.05）。PEEP组与PLV组治疗2小时后，PaO2/FiO2更高（427±20与263±37），死腔通气更低（4±3与28±7%）（均p < 0.05），而肺顺应性有升高趋势（26±2与20±2），分流分数有降低趋势（0±0与7±4）。然而，与PLV组相比，PEEP组的心脏指数、每搏指数和全身氧输送量降低了30%至60%（均p < 0.05）。此外，尽管两种治疗方式下挫伤肺的损伤程度相似，但PEEP组对侧肺的继发性损伤（表现为肺泡内出血）比PLV组更严重。
PEEP和PLV均可改善严重单侧肺挫伤后的肺功能，但PEEP会引起不良的血流动力学和组织学改变，而PLV则不会。这些数据表明，PLV是一种有前景的新型通气策略，可改善单侧肺挫伤，减轻对侧未受伤肺的继发性损伤。
