Dipartimento Area Emergenza Urgenza, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy.
Department of Pathophysiology and Transplantation, University of Milan, Via Francesco Sforza 35, Milan, 20122, Italy.
BMC Anesthesiol. 2024 Nov 14;24(1):415. doi: 10.1186/s12871-024-02806-0.
Transpulmonary pressure is the effective pressure across the lung parenchyma and has been proposed as a guide for mechanical ventilation. The pleural pressure is challenging to directly measure in clinical setting and esophageal manometry using esophageal balloon catheters was suggested for estimation. However, the accuracy of using esophageal pressure to estimate pleural pressure is debated due to variability in the mechanical properties of respiratory system, esophagus and esophageal catheter. Furthermore, while a vertical pleural pressure gradient exists across lung regions, esophageal pressure balloon provides a single value, representing, at most, the pressure surrounding the esophagus.
In a swine model with a preserved esophagus and a single homogenous, easily measurable intrathoracic pressure, we evaluated esophageal pressure's agreement with intrathoracic pressure at different positive end-expiratory pressure (PEEP) levels (0, 5, 10, 15 cmHO). We assessed the improvement of measurement accuracy by correcting absolute esophageal values using a previously described technique, that accounts for the pressure generated by the esophageal wall in response to esophageal balloon inflation. The study involved five swine, wherein two different esophageal catheters were used alongside the four distinct PEEP levels. Swings, uncorrected and corrected absolute esophageal pressures (end-inspiratory, end-expiratory) were compared with their respective intrathoracic pressures. The effect of correction technique was assessed with manual incremental step inflation procedure.
We found that both catheters significantly overestimated absolute esophageal pressure compared to intrathoracic pressure (5.01 ± 3.32 and 6.06 ± 5.62 cmHO at end-expiration and end-inspiration, respectively), with error increasing at higher positive end-expiratory pressure levels (end-expiration: 2.36 ± 2.03, 3.77 ± 1.37, 6.24 ± 2.51 and 7.69 ± 4.02 for each PEEP level, P < 0.0001; end-inspiration: 1.71 ± 2.10, 3.70 ± 1.73, 7.67 ± 3.62 and 11.14 ± 7.60 for each PEEP level, P = 0.0004). Applying the correction technique significantly improved agreement for absolute values (0.82 ± 1.62 and 1.86 ± 3.94 cmHO at end-expiration and end-inspiration, respectively). Esophageal pressure swings accurately estimated intrathoracic pressure swings at low-medium intrathoracic pressures (-0.64 ± 0.62, -0.07 ± 0.53, 1.43 ± 1.51, and 3.45 ± 3.94 at PEEP 0, 5, 10 and 15 cmHO, respectively; P = 0.0197).
The correction technique, based on the mechanical response of esophageal wall to the balloon inflation, is fundamental for obtaining reliable estimations of absolute intrathoracic pressure values, and for ensuring its correct application in clinical setting.
跨肺压是肺实质的有效压力，已被提议作为机械通气的指导。在临床环境中，很难直接测量胸膜压力，因此建议使用带有食管球囊导管的食管测压来估计。然而，由于呼吸系统、食管和食管导管的机械特性存在差异，使用食管压力估计胸膜压力的准确性存在争议。此外，虽然肺区域存在垂直的胸膜压力梯度，但食管压力球囊提供了一个单一的值，最多代表食管周围的压力。
在具有保留的食管和单一均质、易于测量的胸腔内压力的猪模型中，我们评估了在不同的呼气末正压（PEEP）水平（0、5、10、15 cmH2O）下，食管压力与胸腔内压力的一致性。我们通过使用先前描述的技术来校正绝对食管值，该技术考虑了食管球囊充气引起的食管壁产生的压力，从而提高了测量准确性。该研究涉及五头猪，同时使用了两种不同的食管导管和四个不同的 PEEP 水平。比较了未校正和校正后的绝对食管压力（吸气末、呼气末）与各自的胸腔内压力。通过手动递增步阶充气程序评估了校正技术的效果。
我们发现，两种导管都明显高估了绝对食管压力与胸腔内压力的关系（呼气末分别为 5.01±3.32 和 6.06±5.62 cmH2O，吸气末分别为 5.01±3.32 和 6.06±5.62 cmH2O），随着正压呼气末压力水平的升高，误差增大（呼气末：每个 PEEP 水平分别为 2.36±2.03、3.77±1.37、6.24±2.51 和 7.69±4.02，P<0.0001；吸气末：1.71±2.10、3.70±1.73、7.67±3.62 和 11.14±7.60，每个 PEEP 水平，P=0.0004）。应用校正技术显著改善了绝对数值的一致性（呼气末分别为 0.82±1.62 和 1.86±3.94 cmH2O，吸气末分别为 0.82±1.62 和 1.86±3.94 cmH2O）。食管压力波动准确地估计了胸腔内压力在中低胸腔内压力下的波动（PEEP 为 0、5、10 和 15 cmH2O 时，分别为-0.64±0.62、-0.07±0.53、1.43±1.51 和 3.45±3.94；P=0.0197）。
基于食管壁对球囊充气的机械反应的校正技术，对于获得可靠的胸腔内压力绝对值估计值以及确保其在临床环境中的正确应用至关重要。
