Liu Yang, Wei Lu-qing, Lü Fu-yun, Wang Huo, Cao Wen-li, Su Bin
Department of Respiratory Medicine, Affiliated Hospital, Police Army Medical College, Tianjin 300162, China.
Zhonghua Jie He He Hu Xi Za Zhi. 2007 Oct;30(10):756-60.
To evaluate the effects of external positive end-expiratory pressure (PEEPe) on respiratory system mechanics in passively ventilated chronic obstructive pulmonary disease (COPD) patients.
Fifteen patients with acute exacerbation of COPD were randomly enrolled into the study. The patients were admitted into respiratory intensive care unit (RICU) from Jan, 2005 to Jun, 2006 for controlled mechanical ventilation. PEEPe was applied stepwise from zero to 120% of intrinsic PEEP (PEEPi) in all the 15 patients. At each PEEPe level, airway resistance, compliance (Crs), plateau pressure (Pplat), and total PEEP (PEEPtot) were measured. According to the changes of Pplat after PEEPe application, the patients were divided into 2 sub-groups, abnormal response group (n=11) and a perplexing response group (n=4).
In all of the 15 patients, airway resistance at PEEPe equal to 80% and 100% of PEEPi (18.5+/-2.0) cm H2O.L(-1).s(-1) (1 cm H2O=0.098 kPa), (18.0+/-2.2) cm H2O.L(-1).s(-1) were significantly lower than that at zero PEEPe [(23.0+/-2.9) cm H2O.L(-1).s(-1), t=5.36, 6.27 respectively, all P<0.01]. At PEEPe levels equal to 120% of PEEPi, airway resistance (17.3+/-2.1) cm H2O.L(-1).s(-1) and PEEPtot (12.7+/-2.2) cm H2O were significantly different compared with those at zero PEEPe (23.0+/-2.9) cm H2O. L(-1).s(-1), (10.0+/-1.1) cm H2O (t=6.79, -3.90 respectively, all P<0.01). There were no significant differences in baseline PEEPi levels (10.0+/-1.0) cm H2O, (10.0+/-1.4) cm H2O, resistance (22.8+/- 1.9) cm H2O.L(-1).s(-1), (23.1+/-4.1) cm H2O.L(-1).s(-1), Crs (39+/-6) ml/cm H2O, (42+/-9) ml/cm H2O and Pplat (20+/-4) cm H2O, (21+/-3) cm H2O between the normal response and the perplexing response groups (t=0.03, 0.10, 0.60, 0.15 respectively, all P>0.05). However, the corresponding values of Pplat changes at different PEEPe levels in the normal response group [DeltaPplat40 (-0.020+/-0.970) cm H2O, DeltaPplat80 (1.6+/-1.0) cm H2O, DeltaPplat100 (4.0+/-2.9) cm H2O, DeltaPplat120 (6.4+/-3.3) cm H2O] were found to be significantly different compared with those in the perplexing response group [DeltaPplat40 (-7.500+/-0.920) cm H2O, DeltaPplat80 (-4.4+/-1.4) cm H2O, DeltaPplat100 (-3.8+/-1.9) cm H2O, DeltaPplat120 (-1.6+/-1.2) cm H2O] (t=-9.64, -5.90, -3.80, -3.92 respectively, all P<0.01).
At least in some passively ventilated COPD patients, the applied PEEPe may offer benefit by decreasing the Pplat.
评估呼气末正压（PEEPe）对被动通气的慢性阻塞性肺疾病（COPD）患者呼吸系统力学的影响。
15例COPD急性加重患者被随机纳入研究。2005年1月至2006年6月期间，这些患者入住呼吸重症监护病房（RICU）接受控制性机械通气。15例患者均从0开始逐步增加PEEPe至内源性呼气末正压（PEEPi）的120%。在每个PEEPe水平，测量气道阻力、顺应性（Crs）、平台压（Pplat）和总呼气末正压（PEEPtot）。根据应用PEEPe后Pplat的变化，将患者分为2个亚组，异常反应组（n = 11）和复杂反应组（n = 4）。
15例患者中，当PEEPe等于PEEPi的80%和100%时，气道阻力分别为（18.5±2.0）cmH₂O·L⁻¹·s⁻¹（1cmH₂O = 0.098kPa）、（18.0±2.2）cmH₂O·L⁻¹·s⁻¹，显著低于PEEPe为0时的气道阻力[（23.0±2.9）cmH₂O·L⁻¹·s⁻¹，t分别为5.36、6.27，均P < 0.01]。当PEEPe等于PEEPi的120%时，气道阻力（17.3±2.1）cmH₂O·L⁻¹·s⁻¹和PEEPtot（12.7±2.2）cmH₂O与PEEPe为0时[（23.0±2.9）cmH₂O·L⁻¹·s⁻¹，（10.0±1.1）cmH₂O]相比有显著差异（t分别为6.79、-3.90，均P < 0.01）。正常反应组和复杂反应组的基线PEEPi水平[（10.0±1.0）cmH₂O，（10.0±1.4）cmH₂O]、阻力[（22.8±1.9）cmH₂O·L⁻¹·s⁻¹，（23.1±4.1）cmH₂O·L⁻¹·s⁻¹]、Crs[（39±6）ml/cmH₂O，（42±9）ml/cmH₂O]和Pplat[（20±4）cmH₂O，（21±3）cmH₂O]无显著差异（t分别为0.03、0.10、0.60、0.15，均P > 0.05）。然而，正常反应组在不同PEEPe水平下Pplat变化的相应值[ΔPplat40（-0.020±0.970）cmH₂O，ΔPplat80（1.6±1.0）cmH₂O，ΔPplat100（4.0±2.9）cmH₂O，ΔPplat120（6.4±3.3）cmH₂O]与复杂反应组[ΔPplat40（-7.500±0.920）cmH₂O，ΔPplat80（-4.4±1.4）cmH₂O，ΔPplat100（-3.8±1.9）cmH₂O，ΔPplat120（-1.6±1.2）cmH₂O]相比有显著差异（t分别为-9.64、-5.90、-3.80、-3.92，均P < 0.01）。
至少在一些被动通气的COPD患者中，应用PEEPe可能通过降低Pplat而带来益处。
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