如何正确测量食道压

文章

作者: Jean-Michel Arnal，高级医师，Sainte Musse 医院，Toulon，法国

日期: 19.10.2018

Last change: 09.09.2020

Formatting

最近的一项生理学研究表明，食道压可估计在所有 PEEP 水平下胸中部的胸腔压。因此，食道压的绝对测量值有利于设置 PEEP 和监测跨肺压。

初始放置和充气

那么如何正确测量食道压呢？

食道气囊必须正确放置和充气，然后验证放置是否正确。

食道气囊的最佳位置是食道下三分之一处，距离鼻孔 35–45 cm。在病人处于半仰卧位的情况下，首先将空气囊插入胃中，其位于距离鼻孔约 50–60 cm 处。将气囊充气至标准容量（Cooper Surgical 导管为 1 ml，Nutrivent 导管为 4 ml）。无论是被动呼吸还是自主呼吸的病人，在吸气过程中胃压都显示正偏移。通过轻轻手动按压上腹部来确定胃的位置，此操作显示胃压立即增加（见图 1）。

与充气气囊一起回撤

然后，在气囊仍然充气的情况下轻轻回撤食道导管，以便将气囊放置在食道下三分之一处。在从胃压（见图 2）到食道压（见图 3）的变化过程中，出现压力波形的基线变化和心脏振荡。

食道压偏移

被动型病人在吸气过程中显示食道压正偏移（见图 4），但自主呼吸病人显示负偏移（见图 5）。如果心脏振荡使食道压信号变形，您可以再将导管回撤 2–5 cm。

为气囊充气

气囊充分充气所需的空气容量应单独滴定。只可能在被动型病人中进行此操作。根据 Mojoli 等人 (2016) 提出的方法，Cooper Surgical 导管气囊以 0.5 ml 步幅从 0.5 ml 逐渐充气至 3 ml，Nutrivent 导管气囊以 1 ml 步幅从 1 ml 逐渐充气至 8 ml（见图 6）。在气囊渐进充气过程中，食道压的基线增加，食道压偏移的幅度改变。充分的充气容量与食道压最大偏移相关。如果两个不同的充气容量显示相同幅度的食道压偏移，则选择最低的充气容量。

验证

一旦气囊在食道中正确放置并充气，就通过闭塞试验进行验证。其原理是在呼气末关闭气道以改变气道压力，然后验证食道压的变化量是否相同。

在被动型病人中，您可以执行呼气末闭塞。当呼气阀关闭时，外部手动按压胸腔两侧的胸廓，以观察气道和食道压力的正偏移。气道和食道压力增加的幅度应该相同。换言之，跨肺压不应改变（见图 7）。

在主动型病人中，动态闭塞试验也采用呼气末闭塞。无需手动按压胸部，因为病人在闭塞期间会自发吸气。结果是气道和食道压力负偏移。气道和食道压力下降的幅度应相同，即跨肺压不应改变（见图 8）。

如果您想持续监测食道压，则务必重新评估正确的位置和充气容量。

完整引文如下： (Yoshida T, Amato MBP, Grieco DL, et al. Esophageal Manometry and Regional Transpulmonary Pressure in Lung Injury. Am J Respir Crit Care Med. 2018;197(8):1018-1026. doi:10.1164/rccm.201709-1806OC1, Mojoli F, Iotti GA, Torriglia F, et al. In vivo calibration of esophageal pressure in the mechanically ventilated patient makes measurements reliable.Crit Care.2016;20:98. Published 2016 Apr 11. doi:10.1186/s13054-016-1278-52, Baydur A, Behrakis PK, Zin WA, Jaeger M, Milic-Emili J. A simple method for assessing the validity of the esophageal balloon technique. Am Rev Respir Dis. 1982;126(5):788-791. doi:10.1164/arrd.1982.126.5.7883, Akoumianaki E, Maggiore SM, Valenza F, et al. The application of esophageal pressure measurement in patients with respiratory failure. Am J Respir Crit Care Med. 2014;189(5):520-531. doi:10.1164/rccm.201312-2193CI4, Mauri T, Yoshida T, Bellani G, et al. Esophageal and transpulmonary pressure in the clinical setting: meaning, usefulness and perspectives. Intensive Care Med. 2016;42(9):1360-1373. doi:10.1007/s00134-016-4400-x5)

脚注

参考文献

1. Yoshida T, Amato MBP, Grieco DL, et al. Esophageal Manometry and Regional Transpulmonary Pressure in Lung Injury. Am J Respir Crit Care Med. 2018;197(8):1018-1026. doi:10.1164/rccm.201709-1806OC
2. Mojoli F, Iotti GA, Torriglia F, et al. In vivo calibration of esophageal pressure in the mechanically ventilated patient makes measurements reliable. Crit Care. 2016;20:98. Published 2016 Apr 11. doi:10.1186/s13054-016-1278-5
3. Baydur A, Behrakis PK, Zin WA, Jaeger M, Milic-Emili J. A simple method for assessing the validity of the esophageal balloon technique. Am Rev Respir Dis. 1982;126(5):788-791. doi:10.1164/arrd.1982.126.5.788
4. Akoumianaki E, Maggiore SM, Valenza F, et al. The application of esophageal pressure measurement in patients with respiratory failure. Am J Respir Crit Care Med. 2014;189(5):520-531. doi:10.1164/rccm.201312-2193CI
5. Mauri T, Yoshida T, Bellani G, et al. Esophageal and transpulmonary pressure in the clinical setting: meaning, usefulness and perspectives. Intensive Care Med. 2016;42(9):1360-1373. doi:10.1007/s00134-016-4400-x

Esophageal Manometry and Regional Transpulmonary Pressure in Lung Injury.

Yoshida T, Amato MBP, Grieco DL, et al. Esophageal Manometry and Regional Transpulmonary Pressure in Lung Injury. Am J Respir Crit Care Med. 2018;197(8):1018-1026. doi:10.1164/rccm.201709-1806OC

Link to article

RATIONALE

Esophageal manometry is the clinically available method to estimate pleural pressure, thus enabling calculation of transpulmonary pressure (Pl). However, many concerns make it uncertain in which lung region esophageal manometry reflects local Pl.

OBJECTIVES

To determine the accuracy of esophageal pressure (Pes) and in which regions esophageal manometry reflects pleural pressure (Ppl) and Pl; to assess whether lung stress in nondependent regions can be estimated at end-inspiration from Pl.

METHODS

In lung-injured pigs (n = 6) and human cadavers (n = 3), Pes was measured across a range of positive end-expiratory pressure, together with directly measured Ppl in nondependent and dependent pleural regions. All measurements were obtained with minimal nonstressed volumes in the pleural sensors and esophageal balloons. Expiratory and inspiratory Pl was calculated by subtracting local Ppl or Pes from airway pressure; inspiratory Pl was also estimated by subtracting Ppl (calculated from chest wall and respiratory system elastance) from the airway plateau pressure.

MEASUREMENTS AND MAIN RESULTS

In pigs and human cadavers, expiratory and inspiratory Pl using Pes closely reflected values in dependent to middle lung (adjacent to the esophagus). Inspiratory Pl estimated from elastance ratio reflected the directly measured nondependent values.

CONCLUSIONS

These data support the use of esophageal manometry in acute respiratory distress syndrome. Assuming correct calibration, expiratory Pl derived from Pes reflects Pl in dependent to middle lung, where atelectasis usually predominates; inspiratory Pl estimated from elastance ratio may indicate the highest level of lung stress in nondependent "baby" lung, where it is vulnerable to ventilator-induced lung injury.

In vivo calibration of esophageal pressure in the mechanically ventilated patient makes measurements reliable.

Mojoli F, Iotti GA, Torriglia F, et al. In vivo calibration of esophageal pressure in the mechanically ventilated patient makes measurements reliable. Crit Care. 2016;20:98. Published 2016 Apr 11. doi:10.1186/s13054-016-1278-5

Link to article

In screening programmes it is important to assess a preliminary effectiveness of the screening method as soon as possible in order to forecast survival figures. In March 1981 a controlled single-view mammographic screening trial for breast cancer was started in the south of Stockholm. The population invited for screening mammography consisted of 40,000 women aged 40-64 years, and 20,000 women served as a well-defined control group. The main aim of the trial was to determine whether repeated mammographic screening could reduce the mortality in the study population (SP) compared to the control population (CP). The cumulative number of advanced mammary carcinomas in the screening and the control populations from the first five years of screening have shown a tendency towards more favourable stages in the screened population aged 40-64 years. A breakdown by age suggests an effect in age group 50-59 years, but not yet in age groups 40-49 and 60-64 years. When comparing the rates of stage II+ cancer, an increased number is found in the study group. As the total rate of breast cancer is higher in SP than in CP, there ought to be a concealed group of stage II+ cancers in the CP which makes the comparison biased. A new approach has been designed, where an estimation of the 'hidden' number of stage II+ cancers in CP is added to the clinically detected cases, and in this respect a comparison has shown a decrease in the cumulative number of advanced cancers in the SP in relation to the CP (p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

A simple method for assessing the validity of the esophageal balloon technique.

Baydur A, Behrakis PK, Zin WA, Jaeger M, Milic-Emili J. A simple method for assessing the validity of the esophageal balloon technique. Am Rev Respir Dis. 1982;126(5):788-791. doi:10.1164/arrd.1982.126.5.788

Link to article

The validity of the conventional esophageal balloon technique as a measure of pleural pressure was tested in 10 subjects in sitting, supine, and lateral positions by occluding the airways at end-expiration and measuring the ratio of changes in esophageal (delta Pes) and mouth pressure (delta Pm) during the ensuing spontaneous occluded inspiratory efforts. Similar measurements were also made during static Mueller maneuvers. In both tests, delta Pes/delta Pm values were close to unity in sitting and lateral positions, whereas in the supine position, substantial deviations from unity were found in some instances. However, by repositioning the balloon to different levels in the esophagus, even in these instances a locus could be found where the delta Pes/delta Pm ratio was close to unity. No appreciable phase difference between delta Pes and delta Pm was found. We conclude that by positioning the balloon according to the "occlusion test" procedure, valid measurements of pleural pressure can be obtained in all the tested body positions.

The application of esophageal pressure measurement in patients with respiratory failure.

Akoumianaki E, Maggiore SM, Valenza F, et al. The application of esophageal pressure measurement in patients with respiratory failure. Am J Respir Crit Care Med. 2014;189(5):520-531. doi:10.1164/rccm.201312-2193CI

Link to article

This report summarizes current physiological and technical knowledge on esophageal pressure (Pes) measurements in patients receiving mechanical ventilation. The respiratory changes in Pes are representative of changes in pleural pressure. The difference between airway pressure (Paw) and Pes is a valid estimate of transpulmonary pressure. Pes helps determine what fraction of Paw is applied to overcome lung and chest wall elastance. Pes is usually measured via a catheter with an air-filled thin-walled latex balloon inserted nasally or orally. To validate Pes measurement, a dynamic occlusion test measures the ratio of change in Pes to change in Paw during inspiratory efforts against a closed airway. A ratio close to unity indicates that the system provides a valid measurement. Provided transpulmonary pressure is the lung-distending pressure, and that chest wall elastance may vary among individuals, a physiologically based ventilator strategy should take the transpulmonary pressure into account. For monitoring purposes, clinicians rely mostly on Paw and flow waveforms. However, these measurements may mask profound patient-ventilator asynchrony and do not allow respiratory muscle effort assessment. Pes also permits the measurement of transmural vascular pressures during both passive and active breathing. Pes measurements have enhanced our understanding of the pathophysiology of acute lung injury, patient-ventilator interaction, and weaning failure. The use of Pes for positive end-expiratory pressure titration may help improve oxygenation and compliance. Pes measurements make it feasible to individualize the level of muscle effort during mechanical ventilation and weaning. The time is now right to apply the knowledge obtained with Pes to improve the management of critically ill and ventilator-dependent patients.

Esophageal and transpulmonary pressure in the clinical setting: meaning, usefulness and perspectives.

Mauri T, Yoshida T, Bellani G, et al. Esophageal and transpulmonary pressure in the clinical setting: meaning, usefulness and perspectives. Intensive Care Med. 2016;42(9):1360-1373. doi:10.1007/s00134-016-4400-x

Link to article

PURPOSE

Esophageal pressure (Pes) is a minimally invasive advanced respiratory monitoring method with the potential to guide management of ventilation support and enhance specific diagnoses in acute respiratory failure patients. To date, the use of Pes in the clinical setting is limited, and it is often seen as a research tool only.

METHODS

This is a review of the relevant technical, physiological and clinical details that support the clinical utility of Pes.

RESULTS

After appropriately positioning of the esophageal balloon, Pes monitoring allows titration of controlled and assisted mechanical ventilation to achieve personalized protective settings and the desired level of patient effort from the acute phase through to weaning. Moreover, Pes monitoring permits accurate measurement of transmural vascular pressure and intrinsic positive end-expiratory pressure and facilitates detection of patient-ventilator asynchrony, thereby supporting specific diagnoses and interventions. Finally, some Pes-derived measures may also be obtained by monitoring electrical activity of the diaphragm.

CONCLUSIONS

Pes monitoring provides unique bedside measures for a better understanding of the pathophysiology of acute respiratory failure patients. Including Pes monitoring in the intensivist's clinical armamentarium may enhance treatment to improve clinical outcomes.