Intensive Care Unit, Liverpool Hospital, South Western Sydney Local Health District, Locked Bag 7103, Liverpool BC, NSW, 1871, Australia.
Maquet Critical Care AB, Solna, Sweden.
Crit Care. 2022 Jul 31;26(1):232. doi: 10.1186/s13054-022-04110-0.
The optimal level of positive end-expiratory pressure (PEEP) during mechanical ventilation for COVID-19 pneumonia remains debated and should ideally be guided by responses in both lung volume and perfusion. Capnodynamic monitoring allows both end-expiratory lung volume ([Formula: see text]) and effective pulmonary blood flow (EPBF) to be determined at the bedside with ongoing ventilation.
Patients with COVID-19-related moderate to severe respiratory failure underwent capnodynamic monitoring of [Formula: see text] and EPBF during a step increase in PEEP by 50% above the baseline (PEEP to PEEP). The primary outcome was a > 20 mm Hg increase in arterial oxygen tension to inspired fraction of oxygen (P/F) ratio to define responders versus non-responders. Secondary outcomes included changes in physiological dead space and correlations with independently determined recruited lung volume and the recruitment-to-inflation ratio at an instantaneous, single breath decrease in PEEP. Mixed factor ANOVA for group mean differences and correlations by Pearson's correlation coefficient are reported including their 95% confidence intervals.
Of 27 patients studied, 15 responders increased the P/F ratio by 55 [24-86] mm Hg compared to 12 non-responders (p < 0.01) as PEEP (11 ± 2.7 cm HO) was increased to PEEP (18 ± 3.0 cm HO). The [Formula: see text] was 461 [82-839] ml less in responders at PEEP (p = 0.02) but not statistically different between groups at PEEP. Responders increased both [Formula: see text] and EPBF at PEEP (r = 0.56 [0.18-0.83], p = 0.03). In contrast, non-responders demonstrated a negative correlation (r = - 0.65 [- 0.12 to - 0.89], p = 0.02) with increased lung volume associated with decreased pulmonary perfusion. Decreased (- 0.06 [- 0.02 to - 0.09] %, p < 0.01) dead space was observed in responders. The change in [Formula: see text] correlated with both the recruited lung volume (r = 0.85 [0.69-0.93], p < 0.01) and the recruitment-to-inflation ratio (r = 0.87 [0.74-0.94], p < 0.01).
In mechanically ventilated patients with moderate to severe COVID-19 respiratory failure, improved oxygenation in response to increased PEEP was associated with increased end-expiratory lung volume and pulmonary perfusion. The change in end-expiratory lung volume was positively correlated with the lung volume recruited and the recruitment-to-inflation ratio. This study demonstrates the feasibility of capnodynamic monitoring to assess physiological responses to PEEP at the bedside to facilitate an individualised setting of PEEP.
NCT05082168 (18th October 2021).
在 COVID-19 肺炎的机械通气中，最佳呼气末正压（PEEP）水平仍存在争议，理想情况下应通过肺容积和灌注的反应来指导。二氧化碳动力学监测允许在持续通气的情况下在床边同时确定呼气末肺容积([Formula: see text])和有效肺血流（EPBF）。
27 例 COVID-19 相关中重度呼吸衰竭患者接受了 PEEP 增加 50%（高于基线 PEEP）时的二氧化碳动力学监测([Formula: see text]和 EPBF)。主要结局是动脉血氧分压与吸入氧分数比（P/F）增加>20mmHg，定义为应答者与无应答者。次要结局包括生理无效腔的变化，并与独立确定的募集肺容积以及瞬时、单呼吸降低 PEEP时的募集-膨胀比相关。采用混合因素方差分析比较组均值差异，采用 Pearson 相关系数进行相关性分析，并报告其 95%置信区间。
在 27 例研究患者中，15 例应答者的 P/F 比值增加了 55[24-86]mmHg，而 12 例无应答者则没有（p<0.01），PEEP（11±2.7cmH2O）增加到 PEEP（18±3.0cmH2O）。应答者的 [Formula: see text]在 PEEP 时减少了 461[82-839]ml（p=0.02），但两组在 PEEP 时无统计学差异。应答者在 PEEP 时增加了 [Formula: see text]和 EPBF（r=0.56[0.18-0.83]，p=0.03）。相比之下，无应答者表现出与肺容积增加相关的负相关（r=-0.65[-0.12 至-0.89]，p=0.02），与肺灌注减少相关。应答者的无效腔减少（-0.06[-0.02 至-0.09]%，p<0.01）。[Formula: see text]的变化与募集肺容积（r=0.85[0.69-0.93]，p<0.01）和募集-膨胀比（r=0.87[0.74-0.94]，p<0.01）相关。
在中重度 COVID-19 呼吸衰竭的机械通气患者中，增加 PEEP 后氧合改善与呼气末肺容积和肺灌注增加相关。[Formula: see text]的变化与募集的肺容积和募集-膨胀比呈正相关。这项研究表明，二氧化碳动力学监测可在床边评估 PEEP 的生理反应，以促进 PEEP 的个体化设置。
NCT05082168（2021 年 10 月 18 日）。
