He Huaiwu, Yuan Siyi, Yi Chi, Long Yun, Zhang Rui, Zhao Zhanqi
Department of Critical Care Medicine, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences, Dongcheng District, Beijing.
Department of Biomedical Engineering, Fourth Military Medical University, Xi'an, China.
Medicine (Baltimore). 2020 Jun 26;99(26):e20891. doi: 10.1097/MD.0000000000020891.
The use of extra-positive end-expiratory pressure (PEEP) at a level of 80% intrinsic-PEEP (iPEEP) to improve ventilation in severe asthma patients with control ventilation remains controversial. Electrical impedance tomography (EIT) may provide regional information for determining the optimal extra-PEEP to overcome gas trapping and distribution. Moreover, the experience of using EIT to determine extra-PEEP in severe asthma patients with controlled ventilation is limited.
A severe asthma patient had 12-cmH2O iPEEP using the end-expiratory airway occlusion method at Zero positive end-expiratory pressures (ZEEP). How to titrate the extra-PEEP to against iPEEP at bedside?
An incremental PEEP titration was performed in the severe asthma patient with mechanical ventilation. An occult pendelluft phenomenon of the ventral and dorsal regions was found during the early and late expiration periods when the extra-PEEP was set to <6 cmH2O. If the extra-PEEP was elevated from 4 to 6 cmH2O, a decrease in the end-expiratory lung impedance (EELI) and a disappearance of the pendelluft phenomenon were observed during the PEEP titration. Moreover, there was broad disagreement as to the "best" extra-PEEP settings according to the various EIT parameters. The regional ventilation delay had the lowest extra-PEEP value (10 cmH2O), whereas the value was 12 cmH2O for the lung collapse/overdistension index and 14 cmH2O for global inhomogeneity.
The extra-PEEP was set at 6 cmH2O, and the severe whistling sound was improved. The patient's condition further became better under the integrated therapy.
A broad literature review shows that this was the 3rd case of using EIT to titrate an extra-PEEP to against PEEPi. Importantly, the visualization of occult pendelluft and possible air release during incremental PEEP titration was documented for the first time during incremental PEEP titration in patients with severe asthma. Examining the presence of the occult pendelluft phenomenon and changes in the EELI by EIT might be an alternative means for determining an individual's extra-PEEP.
在控制通气的重症哮喘患者中，使用高于内源性呼气末正压（iPEEP）80%水平的额外呼气末正压（PEEP）来改善通气仍存在争议。电阻抗断层扫描（EIT）可为确定最佳额外PEEP以克服气体陷闭和分布提供区域信息。此外，在控制通气的重症哮喘患者中使用EIT确定额外PEEP的经验有限。
一名重症哮喘患者在呼气末气道阻断法测得零呼气末正压（ZEEP）时iPEEP为12 cmH₂O。如何在床边滴定额外PEEP以对抗iPEEP？
对该接受机械通气的重症哮喘患者进行了递增式PEEP滴定。当额外PEEP设置为<6 cmH₂O时，在呼气早期和晚期发现了腹侧和背侧区域隐匿的钟摆样呼吸现象。如果将额外PEEP从4 cmH₂O提高到6 cmH₂O，在PEEP滴定过程中观察到呼气末肺阻抗（EELI）降低，钟摆样呼吸现象消失。此外，根据各种EIT参数，对于“最佳”额外PEEP设置存在广泛分歧。区域通气延迟的额外PEEP值最低（10 cmH₂O），而肺萎陷/过度膨胀指数的值为12 cmH₂O，整体不均匀性的值为14 cmH₂O。
额外PEEP设置为6 cmH₂O，严重哮鸣音得到改善。患者在综合治疗下病情进一步好转。
广泛的文献综述表明，这是第三例使用EIT滴定额外PEEP以对抗PEEPi的病例。重要的是，在重症哮喘患者递增式PEEP滴定过程中首次记录到隐匿的钟摆样呼吸现象的可视化以及递增式PEEP滴定期间可能的气体释放。通过EIT检查隐匿的钟摆样呼吸现象的存在以及EELI的变化可能是确定个体额外PEEP的一种替代方法。
