Tusman Gerardo, Böhm Stephan H, Tempra Alejandro, Melkun Fernando, García Eduardo, Turchetto Elsio, Mulder Paul G H, Lachmann Burkhard
Department of Anesthesiology, Hospital Privado de Comunidad, Mar del Plata, Buenos Aires, Argentina. gtusman2hotmail.com
Anesthesiology. 2003 Jan;98(1):14-22. doi: 10.1097/00000542-200301000-00006.
General anesthesia is known to promote atelectasis formation. High inspiratory pressures are required to reexpand healthy but collapsed alveoli. However, in the absence of positive end-expiratory pressure (PEEP), reexpanded alveoli collapse again. Using magnetic resonance imaging, the impact of an alveolar recruitment strategy on the amount and distribution of atelectasis was tested.
The authors prospectively randomized 24 children who met American Society of Anesthesiologists physical status I or II criteria, were aged 6 months-6 yr, and were undergoing cranial magnetic resonance imaging into three groups. After anesthesia induction, in the alveolar recruitment strategy (ARS) group, an alveolar recruitment maneuver was performed by manually ventilating the lungs with a peak airway pressure of 40 cm H2O and a PEEP of 15 cm H2O for 10 breaths. PEEP was then reduced to and kept at 5 cm H2O. The continuous positive airway pressure (CPAP) group received 5 cm H2O of continuous positive airway pressure without recruitment. The zero end-expiratory pressure (ZEEP) group received neither PEEP nor the recruitment maneuver. All patients breathed spontaneously during the procedure. After cranial magnetic resonance imaging, thoracic magnetic resonance imaging was performed.
The atelectatic volume (median, first and third standard quartiles) detected in the ZEEP group was 1.25 (0.75-4.56) cm3 in the right lung and 4.25 (3.2-13.9) cm3 in the left lung. The CPAP group had 9.5 (3.1-23.7) cm3 of collapsed lung tissue in the right lung and 8.8 (5.3-28.5) cm3 in the left lung. Only one patient in the ARS group presented an atelectasis of less than 2 cm3. An uneven distribution of the atelectasis was observed within each lung and between the right and left lungs, with a clear predominance of the left basal paradiaphragmatic regions.
Frequency of atelectasis was much less following the alveolar recruitment strategy, compared with children who did not have the maneuver performed. The mere application of 5 cm H2O of CPAP without a prior recruitment did not show the same treatment effect and showed no difference compared to the control group without PEEP.
已知全身麻醉会促进肺不张的形成。重新扩张健康但塌陷的肺泡需要较高的吸气压力。然而，在没有呼气末正压通气（PEEP）的情况下，重新扩张的肺泡会再次塌陷。本研究使用磁共振成像，测试了肺泡复张策略对肺不张的数量和分布的影响。
作者前瞻性地将24名符合美国麻醉医师协会身体状况I或II标准、年龄在6个月至6岁之间且正在接受头颅磁共振成像检查的儿童随机分为三组。麻醉诱导后，在肺泡复张策略（ARS）组中，通过以40 cm H₂O的气道峰值压力和15 cm H₂O的PEEP手动通气肺部10次来进行肺泡复张操作。然后将PEEP降至并维持在5 cm H₂O。持续气道正压通气（CPAP）组接受5 cm H₂O的持续气道正压通气，不进行复张操作。零呼气末压力（ZEEP）组既不接受PEEP也不进行复张操作。所有患者在手术过程中均自主呼吸。头颅磁共振成像检查后，进行胸部磁共振成像检查。
ZEEP组右肺检测到的肺不张体积（中位数、第一和第三标准四分位数）为1.25（0.75 - 4.56）cm³，左肺为4.25（3.2 - 13.9）cm³。CPAP组右肺有9.5（3.1 - 23.7）cm³的塌陷肺组织，左肺有8.8（5.3 - 28.5）cm³。ARS组只有一名患者的肺不张小于2 cm³。在每个肺内以及左右肺之间观察到肺不张分布不均，左膈下基底区域明显占优势。
与未进行该操作的儿童相比，肺泡复张策略后的肺不张发生率要低得多。单纯应用5 cm H₂O的CPAP而不预先进行复张操作，并未显示出相同的治疗效果，与无PEEP的对照组相比也无差异。
