Klöpping-Ketelaars W A, Havenith M, Maertzdorf W J, Kuipers I M, Blanco C E
Department of Neonatology, University of Limburg, Maastricht, The Netherlands.
Biol Neonate. 1993;64(4):254-60. doi: 10.1159/000243997.
Positive pressure ventilation, using high inspiratory pressures, often causes lung damage. When associated with hypocapnia, it can produce severe focal alveolar alkalosis and can cause damage in areas of low blood flow. A vein-to-vein extracorporeal membrane oxygenator (ECMO) system was used to control blood gases independently of mechanical ventilation in 12 healthy newborn lambs. After connection to the ECMO system, ventilation was started with a peak inspiratory pressure of 35 cm H2O and a positive end-expiratory pressure of 5 cm H2O; the ventilator rate was 40/min with I:E = 1.5 and FiO2 = 1.0. In 6 of the 12 lambs sweep gases through the silicone membrane were regulated to assure arterial normocapnia. The other 6 were ventilated with the same settings and perfused with the same pump flow, but PaCO2 was allowed to fall to hypocapnic levels. The lambs were ventilated for 4 h. Average pH and PaCO2 were 7.62 +/- 0.14 and 2.11 +/- 0.54 kPa, respectively, in the hypocapnic group and 7.39 +/- 0.11 and 4.79 +/- 0.51 kPa in the normocapnic group. After sacrificing the lambs, the lungs were inspected macroscopically and microscopically by computer-assisted morphometry to assess atelectasis and lung edema. Macroscopically there were no hemorrhages, barotrauma or widespread atelectasis of the lungs in either group. The thickness of interlobular lung septa in the right upper lobe was 32.5 +/- 18.0 microns for the hypocapnic group and 29.7 +/- 12.5 microns for the normocapnic group. The parenchymal-alveolar area ratio in the right upper lobe was 28.4 +/- 5.04 and 24.6 +/- 3.75% in the hypocapnic and normocapnic groups, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)
使用高吸气压力的正压通气常常会导致肺损伤。当与低碳酸血症相关时，它会产生严重的局灶性肺泡碱中毒，并可能在低血流区域造成损伤。在12只健康新生羔羊中，使用静脉-静脉体外膜肺氧合（ECMO）系统独立于机械通气来控制血气。连接到ECMO系统后，以吸气峰压35 cmH₂O和呼气末正压5 cmH₂O开始通气；通气频率为40次/分钟，吸呼比（I:E）=1.5，吸入氧浓度（FiO₂）=1.0。在12只羔羊中的6只中，调节通过硅树脂膜的吹扫气体以确保动脉血正常碳酸血症。另外6只以相同设置通气并以相同的泵流量灌注，但允许动脉血二氧化碳分压（PaCO₂）降至低碳酸血症水平。羔羊通气4小时。低碳酸血症组的平均pH值和PaCO₂分别为7.62±0.14和2.11±0.54 kPa，正常碳酸血症组分别为7.39±0.11和4.79±0.51 kPa。处死羔羊后，通过计算机辅助形态学对肺进行宏观和微观检查，以评估肺不张和肺水肿。宏观上，两组肺均无出血、气压伤或广泛的肺不张。低碳酸血症组右上叶肺小叶间隔厚度为32.5±18.0微米，正常碳酸血症组为29.7±12.5微米。低碳酸血症组和正常碳酸血症组右上叶实质-肺泡面积比分别为28.4±5.04%和24.6±3.75%。（摘要截短于250字）
