Scaramuzzo Gaetano, Karbing Dan Stieper, Fogagnolo Alberto, Mauri Tommaso, Spinelli Elena, Mari Matilde, Turrini Cecilia, Montanaro Federica, Volta Carlo Alberto, Rees Stephen Edward, Spadaro Savino
Department of Translational Medicine and for Romagna, University of Ferrara, Ferrara, Italy; and Department of Anesthesia and Intensive Care Medicine, Azienda Ospedaliera Universitaria di Ferrara, Ferrara, Italy.
Department of Health Science and Technology, Aalborg University, Aalborg East, Denmark.
Respir Care. 2023 Jan 30;68(2):188-198. doi: 10.4187/respcare.10242.
COVID-19-related ARDS is characterized by severe hypoxemia with initially preserved lung compliance and impaired ventilation/perfusion (V̇/Q̇) matching. PEEP can increase end-expiratory lung volume, but its effect on V̇/Q̇ mismatch in COVID-19-related ARDS is not clear.
We enrolled intubated and mechanically ventilated subjects with COVID-19 ARDS and used the automatic lung parameter estimator (ALPE) to measure V̇/Q̇. Respiratory mechanics measurements, shunt, and V̇/Q̇ mismatch (low V̇/Q̇ and high V̇/Q̇) were collected at 3 PEEP levels (clinical PEEP = intermediate PEEP, low PEEP [clinical - 50%], and high PEEP [clinical + 50%]). A mixed-effect model was used to evaluate the impact of PEEP on V̇/Q̇. We also investigated if PEEP might have a different effect on V̇/Q̇ mismatch in 2 different respiratory mechanics phenotypes, that is, high elastance/low compliance (phenotype H) and low elastance/high compliance (phenotype L).
Seventeen subjects with COVID-related ARDS age 66 [60-71] y with a P /F of 141 ± 74 mm Hg were studied at low PEEP = 5.6 ± 2.2 cm HO, intermediate PEEP = 10.6 ± 3.8 cm HO, and high PEEP = 15 ± 5 cm HO. Shunt, low V̇/Q̇, high V̇/Q̇, and alveolar dead space were not significantly influenced, on average, by PEEP. Respiratory system compliance decreased significantly when increasing PEEP without significant variation of P /F ( = .26). In the 2 phenotypes, PEEP had opposite effects on shunt, with a decrease in the phenotype L and an increase in phenotype H ( = .048).
In subjects with COVID-related ARDS placed on invasive mechanical ventilation for > 48 h, PEEP had a heterogeneous effect on V̇/Q̇ mismatch and, on average, higher levels were not able to reduce shunt. The subject's compliance could influence the effect of PEEP on V̇/Q̇ mismatch since an increased shunt was observed in subjects with lower compliance, whereas the opposite occurred in those with higher compliance.
新型冠状病毒肺炎（COVID-19）相关急性呼吸窘迫综合征（ARDS）的特征是严重低氧血症，最初肺顺应性保持正常，但通气/灌注（V̇/Q̇）匹配受损。呼气末正压（PEEP）可增加呼气末肺容积，但其对COVID-19相关ARDS中V̇/Q̇不匹配的影响尚不清楚。
我们纳入了接受气管插管和机械通气的COVID-19 ARDS患者，并使用自动肺参数估计器（ALPE）测量V̇/Q̇。在3个PEEP水平（临床PEEP = 中等PEEP、低PEEP [临床 - 50%]和高PEEP [临床 + 50%]）下收集呼吸力学测量值、分流和V̇/Q̇不匹配（低V̇/Q̇和高V̇/Q̇）。使用混合效应模型评估PEEP对V̇/Q̇的影响。我们还研究了PEEP对2种不同呼吸力学表型（即高弹性/低顺应性（表型H）和低弹性/高顺应性（表型L））中V̇/Q̇不匹配是否可能有不同影响。
对17例年龄为66 [60 - 71]岁、P/F为141 ± 74 mmHg的COVID相关ARDS患者进行了研究，低PEEP = 5.6 ± 2.2 cm H₂O、中等PEEP = 10.6 ± 3.8 cm H₂O、高PEEP = 15 ± 5 cm H₂O。平均而言，PEEP对分流、低V̇/Q̇、高V̇/Q̇和肺泡死腔无显著影响。增加PEEP时呼吸系统顺应性显著降低，而P/F无显著变化（P = 0.26）。在2种表型中，PEEP对分流有相反的影响，表型L中分流减少，表型H中分流增加（P = 0.048）。
在接受有创机械通气超过48小时的COVID相关ARDS患者中, PEEP对V̇/Q̇不匹配有不同影响，平均而言，较高水平的PEEP并不能减少分流。患者的顺应性可能会影响PEEP对V̇/Q̇不匹配的作用，因为在顺应性较低的患者中观察到分流增加，而在顺应性较高的患者中则相反。
