The Esophageal Pressure-Guided Ventilation 2 (EPVent2) trial protocol: a multicentre, randomised clinical trial of mechanical ventilation guided by transpulmonary pressure. Fish Emily,Novack Victor,Banner-Goodspeed Valerie M,Sarge Todd,Loring Stephen,Talmor Daniel BMJ open INTRODUCTION:Optimal ventilator management for patients with acute respiratory distress syndrome (ARDS) remains uncertain. Lower tidal volume ventilation appears to be beneficial, but optimal management of positive end-expiratory pressure (PEEP) remains unclear. The Esophageal Pressure-Guided Ventilation 2 Trial (EPVent2) aims to examine the impact of mechanical ventilation directed at maintaining a positive transpulmonary pressure (PTP) in patients with moderate-to-severe ARDS. METHODS AND ANALYSIS:EPVent2 is a multicentre, prospective, randomised, phase II clinical trial testing the hypothesis that the use of a PTP-guided ventilation strategy will lead to improvement in composite outcomes of mortality and time off the ventilator at 28 days as compared with a high-PEEP control. This study will enrol 200 study participants from 11 hospitals across North America. The trial will utilise a primary composite end point that incorporates death and days off the ventilator at 28 days to test the primary hypothesis that adjusting ventilator pressure to achieve positive PTP values will result in improved mortality and ventilator-free days. ETHICS AND DISSEMINATION:Safety oversight will be under the direction of an independent Data and Safety Monitoring Board (DSMB). Approval of the protocol was obtained from the DSMB prior to enrolling the first study participant. Approvals of the protocol as well as informed consent documents were also obtained from the Institutional Review Board of each participating institution prior to enrolling study participants at each respective site. The findings of this investigation, as well as associated ancillary studies, will be disseminated in the form of oral and abstract presentations at major national and international medical specialty meetings. The primary objective and other significant findings will also be presented in manuscript form. All final, published manuscripts resulting from this protocol will be submitted to PubMed Central in accordance with the National Institute of Health Public Access Policy. TRIAL REGISTRATION NUMBER:ClinicalTrials.gov under number NCT01681225. 10.1136/bmjopen-2014-006356
    Technical aspects of bedside respiratory monitoring of transpulmonary pressure. Mojoli Francesco,Torriglia Francesca,Orlando Anita,Bianchi Isabella,Arisi Eric,Pozzi Marco Annals of translational medicine Transpulmonary pressure, that is the difference between airway pressure (Paw) and pleural pressure, is considered one of the most important parameters to know in order to set a safe mechanical ventilation in acute respiratory distress syndrome (ARDS) patients but also in critically ill obese patients, in abdominal pathologies or in pathologies affecting the chest wall itself. Transpulmonary pressure should rely on the assessment of intrathoracic pleural pressure. Esophageal pressure (Pes) is considered the best surrogate of pleural pressure in critically ill patients, but concerns about its reliability exist. The aim of this article is to describe the technique of Pes measurement in mechanically ventilated patients: the catheter insertion, the proper balloon placement and filling, the validation test and specific procedures to remove the main artifacts will be discussed. 10.21037/atm.2018.08.37
    Esophageal pressure balloon and transpulmonary pressure monitoring in airway pressure release ventilation: a different approach. Daoud Ehab G,Yamasaki Kimiyo H,Nakamoto Keith,Wheatley Denise Canadian journal of respiratory therapy : CJRT = Revue canadienne de la therapie respiratoire : RCTR This is a case of Acute Respiratory Distress Syndrome managed using esophageal balloon catheter to adjust inspiratory pressure and positive end expiratory pressure according to the inspiratory and expiratory transpulmonary pressures. There are no studies that examine the transpulmonary pressures in airway pressure release ventilation (APRV). We aimed to test the feasibility of using the esophageal balloon in the nonconventional mode of APRV. All pressures were observed when switching the mode from a pressure-controlled mode to APRV using the same inspiratory pressure and using various incremental release times (T)to calculate the expiratory transpulmonary pressure. At all T levels the transpulmonary pressure at end exhalation was in the negative value indicating alveolar collapse. A larger study is needed to confirm our findings and to help guide setting APRV. 10.29390/cjrt-2018-010
    Transpulmonary driving pressure, without esophageal pressure measurements, instead of airway driving pressure. Stenqvist Ola Intensive care medicine 10.1007/s00134-020-06243-8
    Should we titrate ventilation based on driving pressure? Maybe not in the way we would expect. Pelosi Paolo,Ball Lorenzo Annals of translational medicine Mechanical ventilation maintains adequate gas exchange in patients during general anaesthesia, as well as in critically ill patients without and with acute respiratory distress syndrome (ARDS). Optimization of mechanical ventilation is important to minimize ventilator induced lung injury and improve outcome. Tidal volume (V), positive end-expiratory pressure (PEEP), respiratory rate (RR), plateau pressures as well as inspiratory oxygen are the main parameters to set mechanical ventilation. Recently, the driving pressure (∆P), i.e., the difference of the plateau pressure and end-expiratory pressure of the respiratory system or of the lung, has been proposed as a key role parameter to optimize mechanical ventilation parameters. The ∆P depends on the V as well as on the relative balance between the amount of aerated and/or overinflated lung at end-expiration and end-inspiration at different levels of PEEP. During surgery, higher ∆P, mainly due to V, was progressively associated with an increased risk to develop post-operative pulmonary complications; in two large randomized controlled trials the reduction in ∆P by PEEP did not result in better outcome. In non-ARDS patients, ∆P was not found even associated with morbidity and mortality. In ARDS patients, an association between ∆P (higher than 13-15 cmHO) and mortality has been reported. In several randomized controlled trials, when ∆P was minimized by the use of higher PEEP with or without recruitment manoeuvres, this strategy resulted in equal or even higher mortality. No clear data are currently available about the interpretation and clinical use of ∆P during assisted ventilation. In conclusion, ∆P is an indicator of severity of the lung disease, is related to V size and associated with complications and mortality. We advocate the use of ∆P to optimize individually V but not PEEP in mechanically ventilated patients with and without ARDS. 10.21037/atm.2018.09.48
    Transpulmonary pressure: importance and limits. Grieco Domenico Luca,Chen Lu,Brochard Laurent Annals of translational medicine Transpulmonary pressure (P) is computed as the difference between airway pressure and pleural pressure and separates the pressure delivered to the lung from the one acting on chest wall and abdomen. Pleural pressure is measured as esophageal pressure (P) through dedicated catheters provided with esophageal balloons. We discuss the role of P in assessing the effects of mechanical ventilation in patients with acute respiratory distress syndrome (ARDS). In the supine position, directly measured P represents the pressure acting on the alveoli and airways. Because there is a pressure gradient in the pleural space from the non-dependent to the dependent zones, the pressure in the esophagus probably represents the pressure at a mid-level between sternal and vertebral regions. For this reason, it has been proposed to set the end-expiratory pressure in order to get a positive value of P. This improves oxygenation and compliance. P can also be estimated from airway pressure plateau and the ratio of lung to respiratory elastance (elastance-derived method). Some data suggest that this latter calculation may better estimate P in the nondependent lung zones, at risk for hyperinflation. Elastance-derived P at end-inspiration (P) may be a good surrogate of end-inspiratory lung stress for the "baby lung", at least in non-obese patients. Limiting end-inspiratory P to 20-25 cmHO appears physiologically sound to mitigate ventilator-induced lung injury (VILI). Last, lung driving pressure (∆P) reflects the tidal distending pressure. Changes in P may also be assessed during assisted breathing to take into account the additive effects of spontaneous breathing and mechanical breaths on lung distension. In summary, despite limitations, assessment of P allows a deeper understanding of the risk of VILI and may potentially help tailor ventilator settings. 10.21037/atm.2017.07.22
    Driving Pressure and Transpulmonary Pressure: How Do We Guide Safe Mechanical Ventilation? Williams Elizabeth C,Motta-Ribeiro Gabriel C,Vidal Melo Marcos F Anesthesiology 10.1097/ALN.0000000000002731
    Regional distribution of transpulmonary pressure. Silva Pedro Leme,Gama de Abreu Marcelo Annals of translational medicine The pressure across the lung, so-called transpulmonary pressure (P), represents the main force acting toward to provide lung movement. During mechanical ventilation, P is provided by respiratory system pressurization, using specific ventilator setting settled by the operator, such as: tidal volume (V), positive end-expiratory pressure (PEEP), respiratory rate (RR), and inspiratory airway flow. Once P is developed throughout the lungs, its distribution is heterogeneous, being explained by the elastic properties of the lungs and pleural pressure gradient. There are different methods of P calculation, each one with importance and some limitations. Among the most known, it can be quoted: (I) direct measurement of P; (II) elastance derived method at end-inspiration of P; (III) transpulmonary driving pressure. Recent studies using pleural sensors in large animal models as also in human cadaver have added new and important information about P heterogeneous distribution across the lungs. Due to this heterogeneous distribution, lung damage could happen in specific areas of the lung. In addition, it is widely accepted that high P can cause lung damage, however the way it is delivered, whether it's compressible or tensile, may also further damage despite the values of P achieved. According to heterogeneous distribution of P across the lungs, the interstitium and lymphatic vessels may also interplay to disseminate lung inflammation toward peripheral organs through thoracic lymph tracts. Thus, it is conceivable that juxta-diaphragmatic area associated strong efforts leading to high values of P may be a source of dissemination of inflammatory cells, large molecules, and plasma contents able to perpetuate inflammation in distal organs. 10.21037/atm.2018.10.03
    Should we titrate positive end-expiratory pressure based on an end-expiratory transpulmonary pressure? Marini John J Annals of translational medicine Arguments continue to swirl regarding the need for and best method of positive end-expiratory pressure (PEEP) titration. An appropriately conducted decremental method that uses modest peak pressures for the recruiting maneuver (RM), a lung protective tidal excursion, relatively small PEEP increments and appropriate timing intervals is currently the most logical and attractive option, particularly when the esophageal balloon pressure (Pes) is used to calculate transpulmonary driving pressures relevant to the lung. The setting of PEEP by the Pes-guided end-expiratory pressure at the 'polarity transition' point of the transmural end-expiratory pressure is quite relevant to the locale of the esophageal balloon catheter. Its desirability, however, is limited by its tendency to encourage PEEP levels that are higher than most other PEEP titration methods. These Pes-set PEEP values promote higher mean airway pressures and are likely to be unnecessary when small tidal driving pressures are in use. Because high airway pressures increase global lung stress and risk hemodynamic compromise, the Pes-determined PEEP would seem associated with a relatively high hazard to benefit ratio for many patients. 10.21037/atm.2018.08.22
    Non-invasive method to detect high respiratory effort and transpulmonary driving pressures in COVID-19 patients during mechanical ventilation. Roesthuis Lisanne,van den Berg Maarten,van der Hoeven Hans Annals of intensive care BACKGROUND:High respiratory drive in mechanically ventilated patients with spontaneous breathing effort may cause excessive lung stress and strain and muscle loading. Therefore, it is important to have a reliable estimate of respiratory effort to guarantee lung and diaphragm protective mechanical ventilation. Recently, a novel non-invasive method was found to detect excessive dynamic transpulmonary driving pressure (∆P) and respiratory muscle pressure (P) with reasonable accuracy. During the Coronavirus disease 2019 (COVID-19) pandemic, it was impossible to obtain the gold standard for respiratory effort, esophageal manometry, in every patient. Therefore, we investigated whether this novel non-invasive method could also be applied in COVID-19 patients. METHODS:∆P and P were derived from esophageal manometry in COVID-19 patients. In addition, ∆P and P were computed from the occlusion pressure (∆P) obtained during an expiratory occlusion maneuver. Measured and computed ∆P and P were compared and discriminative performance for excessive ∆P and P was assessed. The relation between occlusion pressure and respiratory effort was also assessed. RESULTS:Thirteen patients were included. Patients had a low dynamic lung compliance [24 (20-31) mL/cmHO], high ∆P (25 ± 6 cmHO) and high P (16 ± 7 cmHO). Low agreement was found between measured and computed ∆P and P. Excessive ∆P > 20 cmHO and P > 15 cmHO were accurately detected (area under the receiver operating curve (AUROC) 1.00 [95% confidence interval (CI), 1.00-1.00], sensitivity 100% (95% CI, 72-100%) and specificity 100% (95% CI, 16-100%) and AUROC 0.98 (95% CI, 0.90-1.00), sensitivity 100% (95% CI, 54-100%) and specificity 86% (95% CI, 42-100%), respectively). Respiratory effort calculated per minute was highly correlated with ∆P (for esophageal pressure time product per minute (PTP) r = 0.73; P = 0.0002 and work of breathing (WOB) r = 0.85; P < 0.0001). CONCLUSIONS:∆P and P can be computed from an expiratory occlusion maneuver and can predict excessive ∆P and P in patients with COVID-19 with high accuracy. 10.1186/s13613-021-00821-9
    Can we estimate transpulmonary pressure without an esophageal balloon?-yes. Stenqvist Ola,Persson Per,Lundin Stefan Annals of translational medicine A protective ventilation strategy is based on separation of lung and chest wall mechanics and determination of transpulmonary pressure. So far, this has required esophageal pressure measurement, which is cumbersome, rarely used clinically and associated with lack of consensus on the interpretation of measurements. We have developed an alternative method based on a positive end expiratory pressure (PEEP) step procedure where the PEEP-induced change in end-expiratory lung volume is determined by the ventilator pneumotachograph. In pigs, lung healthy patients and acute lung injury (ALI) patients, it has been verified that the determinants of the change in end-expiratory lung volume following a PEEP change are the size of the PEEP step and the elastic properties of the lung, ∆PEEP × Clung. As a consequence, lung compliance can be calculated as the change in end-expiratory lung volume divided by the change in PEEP and esophageal pressure measurements are not needed. When lung compliance is determined in this way, transpulmonary driving pressure can be calculated on a breath-by-breath basis. As the end-expiratory transpulmonary pressure increases as much as PEEP is increased, it is also possible to determine the end-inspiratory transpulmonary pressure at any PEEP level. Thus, the most crucial factors of ventilator induced lung injury can be determined by a simple PEEP step procedure. The measurement procedure can be repeated with short intervals, which makes it possible to follow the course of the lung disease closely. By the PEEP step procedure we may also obtain information (decision support) on the mechanical consequences of changes in PEEP and tidal volume performed to improve oxygenation and/or carbon dioxide removal. 10.21037/atm.2018.06.05
    Personalized Positive End-Expiratory Pressure in Acute Respiratory Distress Syndrome: Comparison Between Optimal Distribution of Regional Ventilation and Positive Transpulmonary Pressure. Scaramuzzo Gaetano,Spadaro Savino,Dalla Corte Francesca,Waldmann Andreas D,Böhm Stephan H,Ragazzi Riccardo,Marangoni Elisabetta,Grasselli Giacomo,Pesenti Antonio,Volta Carlo Alberto,Mauri Tommaso Critical care medicine OBJECTIVES:Different techniques exist to select personalized positive end-expiratory pressure in patients affected by the acute respiratory distress syndrome. The positive end-expiratory transpulmonary pressure strategy aims to counteract dorsal lung collapse, whereas electrical impedance tomography could guide positive end-expiratory pressure selection based on optimal homogeneity of ventilation distribution. We compared the physiologic effects of positive end-expiratory pressure guided by electrical impedance tomography versus transpulmonary pressure in patients affected by acute respiratory distress syndrome. DESIGN:Cross-over prospective physiologic study. SETTING:Two academic ICUs. PATIENTS:Twenty ICU patients affected by acute respiratory distress syndrome undergoing mechanical ventilation. INTERVENTION:Patients monitored by an esophageal catheter and a 32-electrode electrical impedance tomography monitor underwent two positive end-expiratory pressure titration trials by randomized cross-over design to find the level of positive end-expiratory pressure associated with: 1) positive end-expiratory transpulmonary pressure (PEEPPL) and 2) proportion of poorly or nonventilated lung units (Silent Spaces) less than or equal to 15% (PEEPEIT). Each positive end-expiratory pressure level was maintained for 20 minutes, and afterward, lung mechanics, gas exchange, and electrical impedance tomography data were collected. MEASUREMENTS AND MAIN RESULTS:PEEPEIT and PEEPPL differed in all patients, and there was no correlation between the levels identified by the two methods (Rs = 0.25; p = 0.29). PEEPEIT determined a more homogeneous distribution of ventilation with a lower percentage of dependent Silent Spaces (p = 0.02), whereas PEEPPL was characterized by lower airway-but not transpulmonary-driving pressure (p = 0.04). PEEPEIT was significantly higher than PEEPPL in subjects with extrapulmonary acute respiratory distress syndrome (p = 0.006), whereas the opposite was true for pulmonary acute respiratory distress syndrome (p = 0.03). CONCLUSIONS:Personalized positive end-expiratory pressure levels selected by electrical impedance tomography- and transpulmonary pressure-based methods are not correlated at the individual patient level. PEEPPL is associated with lower dynamic stress, whereas PEEPEIT may help to optimize lung recruitment and homogeneity of ventilation. The underlying etiology of acute respiratory distress syndrome could deeply influence results from each method. 10.1097/CCM.0000000000004439
    Driving airway and transpulmonary pressure are correlated to VILI determinants during controlled ventilation. Pistillo Néstor,Fariña Osvaldo Intensive care medicine 10.1007/s00134-018-5092-1
    Mechanical Ventilation Strategy Guided by Transpulmonary Pressure in Severe Acute Respiratory Distress Syndrome Treated With Venovenous Extracorporeal Membrane Oxygenation. Wang Rui,Sun Bing,Li Xuyan,Tang Xiao,He Hangyong,Li Ying,Yuan Xue,Li Haichao,Chu Huiwen,Tong Zhaohui Critical care medicine OBJECTIVES:Previous studies have suggested that adjusting ventilator settings based on transpulmonary pressure measurements may minimize ventilator-induced lung injury, but this has never been investigated in patients with severe acute respiratory distress syndrome supported with venovenous extracorporeal membrane oxygenation. We aimed to evaluate whether a transpulmonary pressure-guided ventilation strategy would increase the proportion of patients successfully weaned from venovenous extracorporeal membrane oxygenation support in patients with severe acute respiratory distress syndrome. DESIGN:Single-center, prospective, randomized controlled trial. SETTING:Sixteen-bed, respiratory ICU at a tertiary academic medical center. PATIENTS:Severe acute respiratory distress syndrome patients receiving venovenous extracorporeal membrane oxygenation. INTERVENTIONS:One-hundred four patients were randomized to transpulmonary pressure-guided ventilation group (n = 52) or lung rest strategy group (n = 52) groups. Two patients had cardiac arrest during establishment of venovenous extracorporeal membrane oxygenation in the lung rest group did not receive the assigned intervention. Thus, 102 patients were included in the analysis. MEASUREMENTS AND MAIN RESULTS:The proportion of patients successfully weaned from venovenous extracorporeal membrane oxygenation in the transpulmonary pressure-guided group was significantly higher than that in the lung rest group (71.2% vs 48.0%; p = 0.017). Compared with the lung rest group, driving pressure, tidal volumes, and mechanical power were significantly lower, and positive end-expiratory pressure was significantly higher, in the transpulmonary pressure-guided group during venovenous extracorporeal membrane oxygenation support. In the transpulmonary pressure-guided group, levels of interleukin-1β, interleukin-6, and interleukin-8 were significantly lower, and interleukin-10 was significantly higher, than those of the lung rest group over time. Lung density was significantly lower in the transpulmonary pressure-guided group after venovenous extracorporeal membrane oxygenation support than in the lung rest group. CONCLUSIONS:A transpulmonary pressure-guided ventilation strategy could increase the proportion of patients with severe acute respiratory distress syndrome successfully weaned from venovenous extracorporeal membrane oxygenation. 10.1097/CCM.0000000000004445
    Mortality and pulmonary mechanics in relation to respiratory system and transpulmonary driving pressures in ARDS. Baedorf Kassis Elias,Loring Stephen H,Talmor Daniel Intensive care medicine PURPOSE:The driving pressure of the respiratory system has been shown to strongly correlate with mortality in a recent large retrospective ARDSnet study. Respiratory system driving pressure [plateau pressure-positive end-expiratory pressure (PEEP)] does not account for variable chest wall compliance. Esophageal manometry can be utilized to determine transpulmonary driving pressure. We have examined the relationships between respiratory system and transpulmonary driving pressure, pulmonary mechanics and 28-day mortality. METHODS:Fifty-six patients from a previous study were analyzed to compare PEEP titration to maintain positive transpulmonary end-expiratory pressure to a control protocol. Respiratory system and transpulmonary driving pressures and pulmonary mechanics were examined at baseline, 5 min and 24 h. Analysis of variance and linear regression were used to compare 28 day survivors versus non-survivors and the intervention group versus the control group, respectively. RESULTS:At baseline and 5 min there was no difference in respiratory system or transpulmonary driving pressure. By 24 h, survivors had lower respiratory system and transpulmonary driving pressures. Similarly, by 24 h the intervention group had lower transpulmonary driving pressure. This decrease was explained by improved elastance and increased PEEP. CONCLUSIONS:The results suggest that utilizing PEEP titration to target positive transpulmonary pressure via esophageal manometry causes both improved elastance and driving pressures. Treatment strategies leading to decreased respiratory system and transpulmonary driving pressure at 24 h may be associated with improved 28 day mortality. Studies to clarify the role of respiratory system and transpulmonary driving pressures as a prognosticator and bedside ventilator target are warranted. 10.1007/s00134-016-4403-7
    Static and Dynamic Transpulmonary Driving Pressures Affect Lung and Diaphragm Injury during Pressure-controlled versus Pressure-support Ventilation in Experimental Mild Lung Injury in Rats. Pinto Eliete F,Santos Raquel S,Antunes Mariana A,Maia Ligia A,Padilha Gisele A,de A Machado Joana,Carvalho Anna C F,Fernandes Marcos V S,Capelozzi Vera L,de Abreu Marcelo Gama,Pelosi Paolo,Rocco Patricia R M,Silva Pedro L Anesthesiology BACKGROUND:Pressure-support ventilation may worsen lung damage due to increased dynamic transpulmonary driving pressure. The authors hypothesized that, at the same tidal volume (VT) and dynamic transpulmonary driving pressure, pressure-support and pressure-controlled ventilation would yield comparable lung damage in mild lung injury. METHODS:Male Wistar rats received endotoxin intratracheally and, after 24 h, were ventilated in pressure-support mode. Rats were then randomized to 2 h of pressure-controlled ventilation with VT, dynamic transpulmonary driving pressure, dynamic transpulmonary driving pressure, and inspiratory time similar to those of pressure-support ventilation. The primary outcome was the difference in dynamic transpulmonary driving pressure between pressure-support and pressure-controlled ventilation at similar VT; secondary outcomes were lung and diaphragm damage. RESULTS:At VT = 6 ml/kg, dynamic transpulmonary driving pressure was higher in pressure-support than pressure-controlled ventilation (12.0 ± 2.2 vs. 8.0 ± 1.8 cm H2O), whereas static transpulmonary driving pressure did not differ (6.7 ± 0.6 vs. 7.0 ± 0.3 cm H2O). Diffuse alveolar damage score and gene expression of markers associated with lung inflammation (interleukin-6), alveolar-stretch (amphiregulin), epithelial cell damage (club cell protein 16), and fibrogenesis (metalloproteinase-9 and type III procollagen), as well as diaphragm inflammation (tumor necrosis factor-α) and proteolysis (muscle RING-finger-1) were comparable between groups. At similar dynamic transpulmonary driving pressure, as well as dynamic transpulmonary driving pressure and inspiratory time, pressure-controlled ventilation increased VT, static transpulmonary driving pressure, diffuse alveolar damage score, and gene expression of markers of lung inflammation, alveolar stretch, fibrogenesis, diaphragm inflammation, and proteolysis compared to pressure-support ventilation. CONCLUSIONS:In the mild lung injury model use herein, at the same VT, pressure-support compared to pressure-controlled ventilation did not affect biologic markers. However, pressure-support ventilation was associated with a major difference between static and dynamic transpulmonary driving pressure; when the same dynamic transpulmonary driving pressure and inspiratory time were used for pressure-controlled ventilation, greater lung and diaphragm injury occurred compared to pressure-support ventilation. 10.1097/ALN.0000000000003060
    A novel non-invasive method to detect excessively high respiratory effort and dynamic transpulmonary driving pressure during mechanical ventilation. Bertoni Michele,Telias Irene,Urner Martin,Long Michael,Del Sorbo Lorenzo,Fan Eddy,Sinderby Christer,Beck Jennifer,Liu Ling,Qiu Haibo,Wong Jenna,Slutsky Arthur S,Ferguson Niall D,Brochard Laurent J,Goligher Ewan C Critical care (London, England) BACKGROUND:Excessive respiratory muscle effort during mechanical ventilation may cause patient self-inflicted lung injury and load-induced diaphragm myotrauma, but there are no non-invasive methods to reliably detect elevated transpulmonary driving pressure and elevated respiratory muscle effort during assisted ventilation. We hypothesized that the swing in airway pressure generated by respiratory muscle effort under assisted ventilation when the airway is briefly occluded (ΔP) could be used as a highly feasible non-invasive technique to screen for these conditions. METHODS:Respiratory muscle pressure (P), dynamic transpulmonary driving pressure (ΔP, the difference between peak and end-expiratory transpulmonary pressure), and ΔP were measured daily in mechanically ventilated patients in two ICUs in Toronto, Canada. A conversion factor to predict ΔP and P from ΔP was derived and validated using cross-validation. External validity was assessed in an independent cohort (Nanjing, China). RESULTS:Fifty-two daily recordings were collected in 16 patients. In this sample, P and ΔP were frequently excessively high: P exceeded 10 cm HO on 84% of study days and ΔP exceeded 15 cm HO on 53% of study days. ΔP measurements accurately detected P > 10 cm HO (AUROC 0.92, 95% CI 0.83-0.97) and ΔP > 15 cm HO (AUROC 0.93, 95% CI 0.86-0.99). In the external validation cohort (n = 12), estimating P and ΔP from ΔP measurements detected excessively high P and ΔP with similar accuracy (AUROC ≥ 0.94). CONCLUSIONS:Measuring ΔP enables accurate non-invasive detection of elevated respiratory muscle pressure and transpulmonary driving pressure. Excessive respiratory effort and transpulmonary driving pressure may be frequent in spontaneously breathing ventilated patients. 10.1186/s13054-019-2617-0
    Transpulmonary driving pressure during mechanical ventilation-validation of a non-invasive measurement method. Gudmundsson Magni,Persson Per,Perchiazzi Gaetano,Lundin Stefan,Rylander Christian Acta anaesthesiologica Scandinavica BACKGROUND:Transpulmonary driving pressure plays an important role in today's understanding of ventilator induced lung injury. We have previously validated a novel non-invasive method based on stepwise increments of PEEP to assess transpulmonary driving pressure in anaesthetised patients with healthy lungs. The aim of this study was to validate the method in patients who were mechanically ventilated for different diagnoses requiring intensive care. METHODS:We measured transpulmonary pressure (Ptp) and calculated transpulmonary driving pressure (ΔPtp) in 31 patients undergoing mechanical ventilation in an intensive care unit. Parallel triplicate measurements were performed with the PEEP step method (PtpPSM) and the conventional oesophageal balloon method (Ptpconv). Their agreement was compared using the intraclass correlation coefficient (ICC) and the Bland Altman plot. RESULT:The coefficient of variation for the repeated measurements was 4,3 for ΔPtpPSM and 9,2 for ΔPtpconv. The ICC of 0,864 and the Bland Altman plot indicate good agreement between the two methods. CONCLUSION:The non-invasive method can be applied in mechanically ventilated patients to measure transpulmonary driving pressure with good repeatability and accuracy comparable to the traditional oesophageal balloon method. 10.1111/aas.13482