Davidson A, Heckman J L, Donner R M, Miller T F, Shaffer T H, Wolfson M R
Department of Pediatrics, Temple University School of Medicine, Philadelphia, PA 19140, USA.
Eur J Pediatr. 1998 Feb;157(2):138-45. doi: 10.1007/s004310050786.
Gas ventilation following instillation of perfluorochemical (PFC) liquid, partial liquid ventilation (PLV), improves gas exchange and pulmonary mechanics in neonatal animals and humans with severe respiratory distress. The effect of PLV on cardiac contractility, performance, pulmonary blood flow and ductal shunt has not been fully described. To this end, we evaluated these indices of cardiopulmonary function in eight conventionally gas ventilated, surfactant-treated premature lambs (125 days gestation) before and during PLV. Animals were instrumented with central venous and aortic lines. Serial evaluation of arterial blood chemistry/pressure, and pulmonary mechanics was performed; cardiac contractility, performance, pulmonary blood flow and ductal shunts were serially assessed by echocardiography. As compared to conventional gas ventilation, during PLV there was a significant decrease in left ventricular meridian (22.5+/-6.6 SE vs 8.1+/-1.4 SE g/cm2, P < 0.02) and circumferential wall stress (54.1+/-16.5 vs 24.4+/-3.8 SE g/cm2, P < 0.04) at end systole. The fall in wall stress at end systole was associated with a significant decrease in left ventricular internal diameter (1.2+/-0.05 SE vs 1.04+/-0.045 SE cm; P < 0.01). There were no significant changes in heart rate, systemic arterial and central venous pressures, systemic vascular resistance, left ventricular shortening and ejection fractions during PLV. The decrease in wall stress was associated with a significant decrease in mean airway pressures (15.9+/-1.1 SE vs 9.9+/-0.2 SE cmH2O; P < 0.05) and ostensibly a change in intrathoracic pressures during PLV. There were no significant differences in blood flows (pre vs during PLV; ml/min/kg): pulmonary (226+/-62 SE vs 293+/-65 SE), aortic (237+/-36 SE vs 204+/-21 SE), and left to right ductal (119+/-25 SE vs 105.5+/-26 SE) measured before and during PLV.
Cardiac output and pulmonary blood flow do not change significantly during PLV and therefore do not appear to contribute to improved gas exchange. This stable cardiac performance occurs at lower wall stress and thereby more advantageous energetic conditions.
在注入全氟化合物（PFC）液体后进行气体通气，即部分液体通气（PLV），可改善患有严重呼吸窘迫的新生动物和人类的气体交换及肺力学。PLV对心脏收缩性、功能、肺血流量和导管分流的影响尚未完全阐明。为此，我们评估了8只经传统气体通气、表面活性剂治疗的早产羔羊（妊娠125天）在PLV之前及期间的这些心肺功能指标。给动物植入中心静脉和主动脉导管。对动脉血化学/压力及肺力学进行连续评估；通过超声心动图连续评估心脏收缩性、功能、肺血流量和导管分流。与传统气体通气相比，在PLV期间，收缩末期左心室直径（22.5±6.6标准误对8.1±1.4标准误g/cm²，P<0.02）和圆周壁应力（54.1±16.5对24.4±3.8标准误g/cm²，P<0.04）显著降低。收缩末期壁应力的下降与左心室内径的显著减小相关（1.2±0.05标准误对1.04±0.045标准误cm；P<0.01）。在PLV期间，心率、体动脉和中心静脉压力、体循环血管阻力、左心室缩短率和射血分数无显著变化。壁应力的降低与平均气道压力显著降低相关（15.9±1.1标准误对9.9±0.2标准误cmH₂O；P<0.05），且PLV期间胸腔内压力明显改变。PLV之前及期间测量的血流量（ml/min/kg）无显著差异：肺血流量（226±62标准误对293±65标准误）、主动脉血流量（237±36标准误对204±21标准误）和左向右导管分流（119±25标准误对105.5±26标准误）。
在PLV期间心输出量和肺血流量无显著变化，因此似乎对气体交换改善无贡献。这种稳定的心脏功能在较低的壁应力下出现，从而处于更有利的能量状态。
