Esophageal Pressure Measurements Research Articles

Ventilator management using esophageal balloon pressure measurements

Mechanical ventilation provides essential support for patients with acute respiratory failure and provides time for these patients to recover from the primary disorder. Ventilator strategies need to provide adequate oxygenation and avoid barotrauma. This trauma develops when some regions of the lungs are overinflated and develops when some regions are underinflated and have cyclical opening and closing during the respiratory cycle. The ARDS network trial demonstrated that a low tidal volume and low pressure strategy improved outcomes. Subsequent trials have tried to determine the optimal PEEP level in patients with moderate to severe ARDS. The use of esophageal balloons provides information about the transpulmonary pressure at the end of inspiration and the transpulmonary pressure at the end of expiration. However, available studies to date do not demonstrate a definite improvement in outcomes in patients with ventilator adjustments based on esophageal pressures. Beitler et al. randomized 200 patients with moderate to severe ARDS into one group in which PEEP titration was based on esophageal balloon pressure measurements, and a second group in which PEEP titration was based on a high FiO2/PEEP table studied in earlier trials. There were no differences in mortality between the two groups. Reanalysis of this information after the trial was completed suggested that transpulmonary pressures in the range of -2 to + 2 cm H2O at the end of expiration were associated with improved outcomes compared to pressures outside that range.

Impact of Esophageal Pressure Measurement on Pulmonary Hypertension Diagnosis in Patients With Obesity

Elevated intrathoracic pressure could affect pulmonary vascular pressure measurements and influence pulmonary hypertension (PH) diagnosis and classification. Esophageal pressure (Pes) measurement adjusts for the increase in intrathoracic pressure, better reflecting the pulmonary hemodynamics in patients with obesity. In individuals with obesity, what is the impact of adjusting pulmonary hemodynamic determinations for Pes on PH diagnosis and classification? Can Pes be estimated by positional or respiratory hemodynamic changes? In this prospective cohort study, we included patients with obesity who underwent right heart catheterization and demonstrated elevated pulmonary artery wedge pressure (PAWP;≥ 12mmHg). After placement of an esophageal balloon, we performed pressure determination using an air-filled transducer connected to a regular hemodynamic monitor. We measured pulmonary pressures changes when sitting and the variations during the respiratory cycle. We included 53 patients (mean ± SD age, 59 ± 12 years; mean ± SD BMI, 44.4 ± 10.2kg/m2). Supine end-expiratory pressures revealed a mean pulmonary artery pressure of > 20mmHg in all patients and a PAWP of >15mmHg in most patients (n= 50). The Pes adjustment led to a significant decrease in percentage of patients with postcapillary PH (from 60%to 8%) and combined precapillary and postcapillary PH (from 34%to 11%), at the expense of an increase in percentage of patients with no PH (0%to 23%), isolated precapillary PH (2%to 25%), and undifferentiated PH (4%to 34%). Adjusting pulmonary hemodynamics for Pes in patients with obesity leads to a pronounced reduction in the number of patients who receive a diagnosis of postcapillary PH. Measuring Pes should be considered in patients with obesity, particularly those with elevated PAWP.

Progression of type B intramural hematoma in patients with obstructive sleep apnea

ObjectiveIn the present study, we estimated the influence of obstructive sleep apnea (OSA) on the progression of type B intramural hematoma (IMHB). MethodsA total of 127 patients had undergone sleep evaluations and esophageal pressure measurements. The variables associated with aorta-related adverse events and mortality were summarized by logistic regression analysis and Cox proportional hazard models. A competing risk analysis of death was used to estimate aorta- and non–aorta-related mortality. ResultsThe OSA group had a greater aorta-related adverse events rate (46% vs 4%; P < .001). The mean nighttime systolic pressure (odds ratio [OR], 1.24; 95% confidence interval [CI], 1.11-1.38; P < .001) was associated with aorta-related adverse events during the acute phase. Thoracic endovascular aortic repair (hazard ratio [HR], 16.2; 95% CI, 7.68-34.22, P < .001) and mean morning systolic pressure (HR, 1.43; 95% CI, 1.22-1.68; P < .001) were associated with a higher rate of aorta-related adverse events. OSA (HR, 3.19; 95% CI, 2.57-12.15; P < .001) and mean morning systolic pressure (HR, 1.59; 95% CI, 1.27-2.01; P = .002) were significantly associated with aorta-related mortality. Competing risk analysis revealed significantly higher aorta-related mortality in the OSA group (11.8% vs 2.0%; P = .0412). A neutrophil/lymphocyte ratio >3.52 (specificity, 90.2%; sensitivity, 89.5%) and mean platelet volume/platelet ratio >0.049 (specificity, 98.0%; sensitivity, 98.7%) had diagnostic value for detecting OSA in patients with IMHB. ConclusionsThe presence of OSA led to a higher aorta-related adverse event rate and mortality in patients with IMHB. The variables associated with these outcomes included thoracic endovascular aortic repair, mean morning and nighttime systolic pressure, and OSA. The neutrophil/lymphocyte ratio and platelet volume/platelet ratio are valuable for detecting OSA in patients with IMHB.

The Utility of Functional Luminal Imaging Probes Measurements to Diagnose Dysmotility and Their Relationship to Impaired Bolus Clearance.

Functional luminal imaging probes (FLIP) have been used by multiple centers to assess esophagogastric junction (EGJ) function in patients at risk for esophageal obstruction but its role in diagnosing peristaltic disorders is less well studied. In particular, there are no studies comparing the sensitivity of FLIP to diagnose motility abnormalities and impaired bolus transit by high-resolution esophageal manometry with impedance. We prospectively recruited 42 patients undergoing high-resolution esophageal manometry with impedance (HRIM) who also underwent FLIP between 2018 and 2020. HRIM parameters were analyzed using Swallow Gateway software to determine peristaltic and lower esophageal sphincter pressure measurements as well as bolus flow parameters. FLIP tracings were analyzed for the presence of repetitive antegrade contractions (RACs), EGJ distensibility, and associated parameters. Forty-two patients were included (11 controls, 7 achalasia, 16 fundoplication, 8 dysmotility). The mean age of patients was 10.1 ± 0.9 years. There were significant differences in bolus flow parameters across diagnosis with longer bolus presence (BPT) in control patients compared with fundoplication and dysmotility patients. There was a significant correlation between EGJ diameter, EGJ distensibility and bolus flow time (BFT) for solid foods (r2 > 0.518, P < 0.02). The presence of RACs and EGJ relaxation during RACs was associated with a greater BFT and BPT across textures (P < 0.05). Forty-two percentage of patients with absent RACs, however, had clear peristalsis by HRIM. The presence of RACs and EGJ relaxation by FLIP correlate with improved bolus flow. Patients with an absence of RACs need HRIM to confirm any diagnoses of dysmotility.

Advanced respiratory monitoring in mechanically ventilated patients with coronavirus disease 2019-associated acute respiratory distress syndrome.

Purpose of reviewTo summarize the current knowledge about the application of advanced monitoring techniques in coronavirus disease 2019 (COVID-19).Recent findingsDue to the heterogeneity between patients, management of COVID-19 requires daily monitoring of and/or aeration and inspiratory effort. Electrical impedance tomography can be used to optimize positive end-expiratory pressure, monitor the response to changes in treatment or body position and assess pulmonary perfusion and ventilation/perfusion matching. Lung ultrasound is more readily available and can be used to measure and monitor recruitment, provide an indication of diaphragm function and pulmonary perfusion disturbances. Esophageal pressure measurements enable the calculation of the transpulmonary pressure and inspiratory effort in order to prevent excessive stress on the lung. While esophageal pressure measurements are the golden standard in determining inspiratory effort, alternatives like P0.1, negative pressure swing during a single airway occlusion and change in central venous pressure are more readily available and capable of diagnosing extreme inspiratory efforts.SummaryAlthough there is little data on the effectiveness of advanced monitoring techniques in COVID-19, regular monitoring should be a central part of the management of COVID-19-related acute respiratory distress syndrome (C-ARDS).

Novel method of transpulmonary pressure measurement with an air-filled esophageal catheter

BackgroundThere is a strong rationale for proposing transpulmonary pressure-guided protective ventilation in acute respiratory distress syndrome. The reference esophageal balloon catheter method requires complex in vivo calibration, expertise and specific material order. A simple, inexpensive, accurate and reproducible method of measuring esophageal pressure would greatly facilitate the measure of transpulmonary pressure to individualize protective ventilation in the intensive care unit.ResultsWe propose an air-filled esophageal catheter method without balloon, using a disposable catheter that allows reproducible esophageal pressure measurements. We use a 49-cm-long 10 Fr thin suction catheter, positioned in the lower-third of the esophagus and connected to an air-filled disposable blood pressure transducer bound to the monitor and pressurized by an air-filled infusion bag. Only simple calibration by zeroing the transducer to atmospheric pressure and unit conversion from mmHg to cmH2O are required. We compared our method with the reference balloon catheter both ex vivo, using pressure chambers, and in vivo, in 15 consecutive mechanically ventilated patients. Esophageal-to-airway pressure change ratios during the dynamic occlusion test were close to one (1.03 ± 0.19 and 1.00 ± 0.16 in the controlled and assisted modes, respectively), validating the proper esophageal positioning. The Bland–Altman analysis revealed no bias of our method compared with the reference and good precision for inspiratory, expiratory and delta esophageal pressure measurements in both the controlled (largest bias −0.5 cmH2O [95% confidence interval: −0.9; −0.1] cmH2O; largest limits of agreement −3.5 to 2.5 cmH2O) and assisted modes (largest bias −0.3 [−2.6; 2.0] cmH2O). We observed a good repeatability (intra-observer, intraclass correlation coefficient, ICC: 0.89 [0.79; 0.96]) and reproducibility (inter-observer ICC: 0.89 [0.76; 0.96]) of esophageal measurements. The direct comparison with pleural pressure in two patients and spectral analysis by Fourier transform confirmed the reliability of the air-filled catheter-derived esophageal pressure as an accurate surrogate of pleural pressure. A calculator for transpulmonary pressures is available online.ConclusionsWe propose a simple, minimally invasive, inexpensive and reproducible method for esophageal pressure monitoring with an air-filled esophageal catheter without balloon. It holds the promise of widespread bedside use of transpulmonary pressure-guided protective ventilation in ICU patients.

Quantification of airway conductance from noninvasive ventilatory drive in patients with sleep apnea.

Upper airway conductance, the ratio of inspiratory airflow to inspiratory effort, quantifies the degree of airway obstruction in hypopneas observed in sleep apnea. We evaluated the ratio of ventilation to noninvasive ventilatory drive as a surrogate of conductance. Furthermore, we developed and tested a refinement of noninvasive drive to incorporate the interactions of inspiratory flow, pressure, and drive to better estimate conductance. Hypopneas were compiled from existing polysomnography studies with esophageal catheterization in 18 patients with known or suspected sleep apnea, totaling 1,517 hypopneas during NREM sleep. For each hypopnea, reference standard conductance was calculated as the ratio of peak inspiratory flow to esophageal pressure change during inspiration. Ventilatory drive was calculated using the algorithm developed by Terrill et al. and then mathematically modified according to the presence or absence of flow limitation to noninvasively estimate esophageal pressure. The ratio of ventilation to ventilatory drive and the ratio of peak inspiratory flow to estimated esophageal pressure were each compared with the reference standard for all hypopneas and for median values from individual patients. Hypopnea ventilation to drive ratios were of limited correlation with the reference standard (R2 = 0.17, individual hypopneas; R2 = 0.03, median patient values). Modification of drive to estimated pressure yielded estimated conductance, which strongly correlated with reference standard conductance (R2 = 0.49, individual hypopneas; R2 = 0.77, median patient values). We conclude that the severity of airway obstruction during hypopneas may be estimated from noninvasive drive by accounting for mechanical effects of flow on pressure. NEW & NOTEWORTHY Classification of hypopneas as obstructive (decreased upper airway conductance) or central (decreased inspiratory flow commensurate with decreased effort) is complicated by the requirement of invasive methods, such as esophageal manometry. Here, we demonstrate that using a few esophageal pressure measurements to account for the interactions between inspiratory flow, pressure, and noninvasive ventilatory drive allows estimation of upper airway conductance. Further studies may use these findings to quantify airway obstruction completely noninvasively.

Comprehensive Assessment of Respiratory Function, a Step towards Early Weaning from the Ventilator

Methods for assessing diaphragmatic function can be useful in determining the functional status of the respiratory system and can contribute to determining an individual's prognosis, depending on their pathology. They can also be a useful tool for making objective decisions regarding mechanical ventilation weaning and extubation. Esophageal and transdiaphragmatic pressure measurement, diaphragm ultrasound, diaphragmatic excursion, surface electromyography (sEMG) and some serum biomarkers are of increasing interest and use in clinical and intensive care settings to offer a more objective process for withdrawing mechanical ventilation; especially in the situation that we are experiencing with the increased demand for mechanical ventilation to treat patients with Covid-19-associated viral pneumonia. In this literature review, we updated the clinical and physiological indicators with more evidence to improve ventilator withdrawal techniques. We concluded that, to ensure successful extubation in a way that is useful, cost-effective, practical for health personnel and non-invasive for the patient, further studies of novel techniques such as surface electromyography should be implemented.

Patient self-inflicted lung injury (P-SILI) : From pathophysiology to clinical evaluation with differentiated management

Die Etablierung der unterstützten Spontanatmung gilt allgemein als eine vorteilhafte und wenig gefährdende Phase der Beatmungstherapie. Allerdings geben neuere Erkenntnisse Hinweise auf eine potenzielle Schädigung durch exzessive Spontanatembemühungen vor allem bei akuter Lungenschädigung. Das Syndrom wird unter dem Begriff „patient self-inflicted lung injury“ zusammengefasst. Ärzte, Pflegepersonen und Atmungstherapeuten sollten für diese Thematik sensibilisiert werden. Parameter, die mittels Ösophagusdruckmessung oder einfacher Manöver am Respirator bestimmt werden können, sind bei der Entscheidung zur Durchführung und zur Überwachung von Spontanatmung auch in den akuten Phasen der Lungenschädigung hilfreich. Weiterhin gibt es im Umgang mit hohem Atemantrieb oder erhöhter Atemanstrengung therapeutische Möglichkeiten, diesen zu begegnen.

Effect of Therapeutic Hypothermia on Physiologic, Histologic and Metabolomic Markers of Lung Injury in Experimental Acute Respiratory Distress Syndrome

Background Acute respiratory distress syndrome (ARDS) is a severe lung injury characterized by noncardiogenic pulmonary edema and rapid hypoxic respiratory failure. Therapeutic hypothermia improves outcomes of traumatic brain injury and cardiac injuries; however, it has not been widely used or studied in ARDS. Hypothermia may be helpful in reducing injury and inflammation associated with ARDS by reducing pro-inflammatory molecule production. Objective To evaluate the effect of therapeutic hypothermia on the development of injury and inflammation in experimental, short-term ARDS. Hypothesis Hypothermia induced at the onset of lung injury would mitigate histological and serum metabolic changes, as well as changes in respiratory elastance (E) and resistance (R). Methods The Animal Research Committee of the University of British Columbia approved all experimental procedures. Twenty female Yorkshire pigs were divided into 4 groups (n= 5 per group): normothermic control (C), normothermic injured (I), hypothermic control (HC), and hypothermic injured (HI). ARDS was induced via intrapulmonary injection of oleic acid. Hypothermia was induced with a cooling catheter placed into the left jugular vein. The normothermic groups had core temperatures maintained at 36.5-38°C and the hypothermic groups were cooled to 32°C. Animals were euthanized after a 12-hour follow-up period. Respiratory mechanical variables were quantified based the measurements of flow, airway pressure, and esophageal pressure. Tissue samples from the right diaphragmatic lobe were collected after euthanasia and examined for injury score. Plasma samples were collected and 1H-NMR spectroscopy analysis was performed to determine metabolite concentration. Results Therapeutic hypothermia reduced injury in the HI vs. I group (injury score= 0.51±0.18 vs. 0.76±0.06; p<0.05). All cohorts expressed distinct phenotypes with the HI cohort having a reduction in inflammatory metabolites (i.e., succinate) compared to the I cohort. Changes to respiratory mechanics were due to changes in lung E and R (ΔE from pre-injury= 45.55±14.17 cmH2O·l-1; ΔR from pre-injury= 3.07±1.99 cmH2O·l-1·s-1, p<0.05) and not chest-wall E and R (ΔE from pre-injury= 0.73±1.59 cmH2·l-1; ΔR from pre-injury= 0.59±0.14 cmH2O·l-1s-1, p>0.05), with trends for the HI group to have a lower lung R (p=0.99) and E (p=0.93) compared to the I group. Control groups showed no significant change in respiratory mechanics. Conclusion Therapeutic hypothermia canreduce some markers of injury and inflammation associated with ARDS. Further studies are required to determine the effect on longer term outcomes and mortality.

Esophageal pressure monitoring for airway management during catheter ablation of atrial fibrillation.

BackgroundRespiratory management during catheter ablation of atrial fibrillation (AF) is important for the efficacy and safety of the procedure. Obstructive apnea due to an upper airway obstruction might cause serious complications including air embolisms and cardiac tamponade. However, real time monitoring of upper airway obstructions during catheter ablation has not been established. The purpose of the present study was to evaluate esophageal pressure monitoring for respiratory management during catheter ablation of AF.Methods and ResultsTwenty-four consecutive patients (20 men and 4 women; mean age, 61 ± 13 years) with AF who underwent esophageal pressure monitoring during catheter ablation of AF were retrospectively analyzed. The patients were divided into 2 groups. One was the obstructive apnea (OA) group (n = 17), which required airway management tools including nasal airways and/or non-invasive positive airway pressure (NPPV) and the other was the control group (n = 7), which did not require airway management. Esophageal pressure measurements were obtained in all patients, and the OA group exhibited a substantial negative esophageal pressure as compared to the control group (−41.48 ± 19.58 vs. −12.42 ± 5.77 mmHg, p < 0.001). Airway management in the OA group immediately improved the negative esophageal pressure and returned to a normal range (−41.48 ± 19.58 vs. −16 ± 8.1 mmHg, 0 < 0.001) along with a recovery from desaturation.ConclusionsEsophageal pressure monitoring was a simple and effective method for the evaluation and management of obstructive apnea during AF catheter ablation.

Estimation of change in pleural pressure in assisted and unassisted spontaneous breathing pediatric patients using fluctuation of central venous pressure: A preliminary study.

It is important to evaluate the size of respiratory effort to prevent patient self-inflicted lung injury and ventilator-induced diaphragmatic dysfunction. Esophageal pressure (Pes) measurement is the gold standard for estimating respiratory effort, but it is complicated by technical issues. We previously reported that a change in pleural pressure (ΔPpl) could be estimated without measuring Pes using change in CVP (ΔCVP) that has been adjusted with a simple correction among mechanically ventilated, paralyzed pediatric patients. This study aimed to determine whether our method can be used to estimate ΔPpl in assisted and unassisted spontaneous breathing patients during mechanical ventilation. The study included hemodynamically stable children (aged <18 years) who were mechanically ventilated, had spontaneous breathing, and had a central venous catheter and esophageal balloon catheter in place. We measured the change in Pes (ΔPes), ΔCVP, and ΔPpl that was calculated using a corrected ΔCVP (cΔCVP-derived ΔPpl) under three pressure support levels (10, 5, and 0 cmH2O). The cΔCVP-derived ΔPpl value was calculated as follows: cΔCVP-derived ΔPpl = k × ΔCVP, where k was the ratio of the change in airway pressure (ΔPaw) to the ΔCVP during airway occlusion test. Of the 14 patients enrolled in the study, 6 were excluded because correct positioning of the esophageal balloon could not be confirmed, leaving eight patients for analysis (mean age, 4.8 months). Three variables that reflected ΔPpl (ΔPes, ΔCVP, and cΔCVP-derived ΔPpl) were measured and yielded the following results: -6.7 ± 4.8, - -2.6 ± 1.4, and - -7.3 ± 4.5 cmH2O, respectively. The repeated measures correlation between cΔCVP-derived ΔPpl and ΔPes showed that cΔCVP-derived ΔPpl had good correlation with ΔPes (r = 0.84, p< 0.0001). ΔPpl can be estimated reasonably accurately by ΔCVP using our method in assisted and unassisted spontaneous breathing children during mechanical ventilation.

Inferring Respiratory and Circulatory Parameters from Electrical Impedance Tomography With Deep Recurrent Models.

Electrical impedance tomography (EIT) is a noninvasive imaging modality that allows a continuous assessment of changes in regional bioimpedance of different organs. One of its most common biomedical applications is monitoring regional ventilation distribution in critically ill patients treated in intensive care units. In this work, we put forward a proof-of-principle study that demonstrates how one can reconstruct synchronously measured respiratory or circulatory parameters from the EIT image sequence using a deep learning model trained in an end-to-end fashion. For this purpose, we devise an architecture with a convolutional feature extractor whose output is processed by a recurrent neural network. We demonstrate that one can accurately infer absolute volume, absolute flow, normalized airway pressure and within certain limitations even the normalized arterial blood pressure from the EIT signal alone, in a way that generalizes to unseen patients without prior calibration. As an outlook with direct clinical relevance, we furthermore demonstrate the feasibility of reconstructing the absolute transpulmonary pressure from a combination of EIT and absolute airway pressure, as a way to potentially replace the invasive measurement of esophageal pressure. With these results, we hope to stimulate further studies building on the framework put forward in this work.

Analysis of esophageal manometry results and the inflection point of age in 41 volunteers without laryngopharyngeal symptoms

Objective:This study aimed to explore the differences in esophageal pressure at different ages, and to analyze the possible age inflection points of the physiological degeneration of esophageal motility, and to further evaluate whether the degeneration of esophageal kinetics with age is the only risk factor for the occurrence of throat reflux disease （LPRD）. Methods:A solid-state high-resolution esophageal pressure measurement was performed on 41 volunteers without throat symptoms. The Chicago classification data were compared with the manometry results of all volunteers. In addition, the esophageal manometry results were compared among groups with pre-set age inflection point. Results:Most of the volunteers' esophageal pressure measurements were in line with Chicago standards. When the inflection point of age was 55 years, no significant difference was found between the two groups. However, when the inflection point of age was 65 years, a significant difference in the length of the upper esophageal sphincter and the contractile front velocity was found between the two groups（P=0.021 and 0.046 respectively）. Conclusion:Esophageal dynamics was weakened with increasing age in the volunteers without laryngopharyngeal symptoms, which was more obvious after the age of 65, but still within the normal range. The degeneration of esophageal motility is not the only risk factor for LPRD.

Correcting esophageal pressure measurements for patients undergoing mechanical ventilation

Abstract During invasive mechanical ventilation, knowledge of the patient’s respiratory effort is valuable in guiding the clinical team to perform a personalized therapy. The same adjustment of the ventilator can produce excessive transpulmonary pressures for different patients, capable of generating or aggravating pre-existing lung injuries. The measurement of transpulmonary pressure (the difference between airway and pleural pressures) is not easily performed in practice. Although airway pressure measurement is available on most current mechanical ventilators, pleural pressure measurement is indirectly performed using an esophageal balloon. In many cases, esophageal pressure reading takes other phenomena into account and is not a reliable measure of pleural pressure. This work will study system identification techniques to obtain reliable pleural pressures based on esophageal pressure readings, aiming to provide the clinical team with information about the patient’s ventilatory therapy’s real status. By estimating transfer function models, autoregressive with external input (ARX) and output error (OE) polynomial models, waveforms were adjusted in two different patients’ occlusion maneuver data. Different metrics were used to assess the quality of the models obtained. The analysis results showed that the estimation methods used provided plausible representations of the underlying dynamic system. Therefore, there are indications that the system identification techniques presented in this work can be used in general, in a clinical environment, to provide reliable estimates of pleural pressure based on esophageal pressure measurements.

Measurement of esophageal pressure: possible limits to its clinical application.

Measurement of esophageal pressure: possible limits to its clinical application.

Airway pressure morphology and respiratory muscle activity during end-inspiratory occlusions in pressure support ventilation

BackgroundThe driving pressure of the respiratory system is a valuable indicator of global lung stress during passive mechanical ventilation. Monitoring lung stress in assisted ventilation is indispensable, but achieving passive conditions in spontaneously breathing patients to measure driving pressure is challenging. The accuracy of the morphology of airway pressure (Paw) during end-inspiratory occlusion to assure passive conditions during pressure support ventilation has not been examined.MethodsRetrospective analysis of end-inspiratory occlusions obtained from critically ill patients during pressure support ventilation. Flow, airway, esophageal, gastric, and transdiaphragmatic pressures were analyzed. The rise of gastric pressure during occlusion with a constant/decreasing transdiaphragmatic pressure was used to identify and quantify the expiratory muscle activity. The Paw during occlusion was classified in three patterns, based on the differences at three pre-defined points after occlusion (0.3, 1, and 2 s): a “passive-like” decrease followed by plateau, a pattern with “clear plateau,” and an “irregular rise” pattern, which included all cases of late or continuous increase, with or without plateau.ResultsData from 40 patients and 227 occlusions were analyzed. Expiratory muscle activity during occlusion was identified in 79% of occlusions, and at all levels of assist. After classifying occlusions according to Paw pattern, expiratory muscle activity was identified in 52%, 67%, and 100% of cases of Paw of passive-like, clear plateau, or irregular rise pattern, respectively. The driving pressure was evaluated in the 133 occlusions having a passive-like or clear plateau pattern in Paw. An increase in gastric pressure was present in 46%, 62%, and 64% of cases at 0.3, 1, and 2 s, respectively, and it was greater than 2 cmH2O, in 10%, 20%, and 15% of cases at 0.3, 1, and 2 s, respectively.ConclusionsThe pattern of Paw during an end-inspiratory occlusion in pressure support cannot assure the absence of expiratory muscle activity and accurate measurement of driving pressure. Yet, because driving pressure can only be overestimated due to expiratory muscle contraction, in everyday practice, a low driving pressure indicates an absence of global lung over-stretch. A measurement of high driving pressure should prompt further diagnostic workup, such as a measurement of esophageal pressure.

The assessment of esophageal pressure using different devices: a validation study.

Although esophageal pressure measurement could help clinicians to improve the ventilatory management of acute respiratory distress syndrome (ARDS) patients, it has been mainly used in clinical research. Aim of this study was to compare the measurements of end-expiratory esophageal pressure, end-expiratory transpulmonary pressure and lung stress by three systems: a dedicated manual device, taken as gold standard, a new automatic system (Optivent) and a bedside equipment, consisting of a mechanical ventilator and a hemodynamic monitor. In sedated and paralyzed mechanically ventilated ARDS patients the esophageal pressure was measured at three PEEP levels in random fashion (baseline level, 50% higher and 50% lower). Forty patients were enrolled (BMI 25 [23-28] kg/m2, PaO<inf>2</inf>/FiO<inf>2</inf> 187 [137-223] and PEEP 9±3 cmH<inf>2</inf>O). The mean esophageal pressure measured during an expiratory pause by the dedicated system, the bedside system and Optivent were 10.0±4.2, 10±4 and 9.9±4.0 cmH<inf>2</inf>O, respectively. The respective bias and limits of agreement between the dedicated system and Optivent and between the dedicated system and the bedside system were as follows: end-expiratory esophageal pressure, 0.2 cmH<inf>2</inf>O, (-0.4 to 0.9) and -0.1 cmH<inf>2</inf>O (-1.9 to 1.7); end-expiratory transpulmonary pressure, -0.6 cmH<inf>2</inf>O (-1.7 to 0.4) and -0.4 cmH<inf>2</inf>O, (-2.2 to 1.5); lung stress -0.9 cmH<inf>2</inf>O (-3.0 to 1.1) and -1.5 cmH<inf>2</inf>O (-4.4 to 1.4). Both Optivent and the bedside system showed clinically acceptability if compared to the gold standard device. The possibility to apply one of these systems could allow a wider use of esophageal pressure in clinical practice.

A Comparative Trial of the Effectiveness of Nasal Interfaces Used to Deliver Continuous Positive Airway Pressure for a Brief Period in Infants With Transient Tachypnea of the Newborn

IntroductionThere is insufficient data on the effectiveness of the interfaces used for nasal continuous airway pressure (nCPAP) in newborn infants. Transpulmonary pressure (PTP) calculated from a measured esophageal pressure (Pes) could be used as a surrogate for the pressure transmitted to the distal airways during nCPAP. We aimed to compare the effectiveness of two nasal interfaces, the nasal mask and bi-nasal short prongs, during a relatively brief period of respiratory support by calculated PTP (cPTP) in infants with transient tachypnea of the newborn (TTN). MethodsNewborns with TTN who needed respiratory assistance with nCPAP were randomized to use either bi-nasal short prongs or a nasal mask. Esophageal pressure measurements were done in order to calculate PTP with either interface. The primary outcome was the cPTP transmitted with each nasal interface. Esophageal pressure measurements were recorded and PTP values were calculated from Pes measurements at the 1st, 6th, 12th and 24th hours in each patient as long as the respiratory support lasted. ResultsSixty-two newborns with TTN and on nCPAP were randomized into two groups: Group 1 to use bi-nasal short prongs (n: 31) and Group 2 to use a nasal mask (n: 31). Inspiratory and expiratory Pes and cPTP values at the 1st, 6th, 12th and 24th hours were similar with the two interfaces (P<.05). ConclusionsA nasal mask is similarly effective and safe as bi-nasal short prongs during a brief period of non-invasive respiratory support with nCPAP in late preterm and term neonates with TTN.

Esophageal Manometry.

The estimation of pleural pressure with esophageal manometry has been used for decades, and it has been a fertile area of physiology research in healthy subject as well as during mechanical ventilation in patients with lung injury. However, its scarce adoption in clinical practice takes its roots from the (false) ideas that it requires expertise with years of training, that the values obtained are not reliable due to technical challenges or discrepant methods of calculation, and that measurement of esophageal pressure has not proved to benefit patient outcomes. Despites these criticisms, esophageal manometry could contribute to better monitoring, optimization, and personalization of mechanical ventilation from the acute initial phase to the weaning period. This review aims to provide a comprehensive but comprehensible guide addressing the technical aspects of esophageal catheter use, its application in different clinical situations and conditions, and an update on the state of the art with recent studies on this topic and on remaining questions and ways for improvement.