Acute respiratory distress syndrome (ARDS) is a critical condition characterized by acute hypoxemia, non-cardiogenic pulmonary edema, and decreased lung compliance. The Berlin definition, updated in 2012, classifies ARDS severity based on the partial pressure of arterial oxygen/fractional inspired oxygen fraction ratio. Despite various treatment strategies, ARDS remains a significant public health concern with high mortality rates.

To evaluate the implications of driving pressure (DP) in ARDS management and its potential as a protective lung strategy.

We conducted a systematic review using databases including EbscoHost, MEDLINE, CINAHL, PubMed, and Google Scholar. The search was limited to articles published between January 2015 and September 2024. Twenty-three peer-reviewed articles were selected based on inclusion criteria focusing on adult ARDS patients undergoing mechanical ventilation and DP strategies. The literature review was conducted and reported according to PRISMA 2020 guidelines.

DP, the difference between plateau pressure and positive end-expiratory pressure, is crucial in ARDS management. Studies indicate that lower DP levels are significantly associated with improved survival rates in ARDS patients. DP is a better predictor of mortality than tidal volume or positive end-expiratory pressure alone. Adjusting DP by optimizing lung compliance and minimizing overdistension and collapse can reduce ventilator-induced lung injury.

DP is a valuable parameter in ARDS management, offering a more precise measure of lung stress and strain than traditional metrics. Implementing DP as a threshold for safety can enhance protective ventilation strategies, potentially reducing mortality in ARDS patients. Further research is needed to refine DP measurement techniques and validate its clinical application in diverse patient populations.

• Acute respiratory distress syndrome
• Mechanical ventilation
• Driving pressure
• Respiratory care
• Intensive care unit
• Pulmonary disease

• ARDS
• Burn injury
• Inhalation injury
• Mechanical ventilation
• Protective ventilation
• Ventilator-induced lung injury

• Humans
• Respiration, Artificial
• Burns/complications
• Burns/therapy
• Respiratory Distress Syndrome/etiology
• Respiratory Distress Syndrome/therapy
• Critical Illness/therapy
• Respiratory Insufficiency

• 45°
• acute respiratory distress syndrome
• clinical efficacy
• prone position ventilation
• protocol

• APACHE
• Adolescent
• Adult
• Aged
• Female
• Hemodynamics
• Humans
• Male
• Middle Aged
• Oxygen/blood
• Pressure Ulcer/epidemiology
• Prone Position/physiology
• Respiration, Artificial/methods
• Respiratory Distress Syndrome/therapy
• Single-Blind Method
• Young Adult
• Randomized Controlled Trials as Topic

• 2014A020221025 Guangdong Science and Technology Department (CN)

• Automation
• In-silico
• Mechanical ventilation
• PEEP
• Virtual patients

Recent analyses of patient data in acute respiratory distress syndrome (ARDS) showed that a lower ventilator driving pressure was associated with reduced relative risk of mortality. These findings await full validation in prospective clinical trials.

To investigate the association between driving pressures and ventilator induced lung injury (VILI), we calibrated a high fidelity computational simulator of cardiopulmonary pathophysiology against a clinical dataset, capturing the responses to changes in mechanical ventilation of 25 adult ARDS patients. Each of these in silico patients was subjected to the same range of values of driving pressure and positive end expiratory pressure (PEEP) used in the previous analyses of clinical trial data. The resulting effects on several physiological variables and proposed indices of VILI were computed and compared with data relating ventilator settings with relative risk of death.

Three VILI indices: dynamic strain, mechanical power and tidal recruitment, showed a strong correlation with the reported relative risk of death across all ranges of driving pressures and PEEP. Other variables, such as alveolar pressure, oxygen delivery and lung compliance, correlated poorly with the data on relative risk of death.

Our results suggest a credible mechanistic explanation for the proposed association between driving pressure and relative risk of death. While dynamic strain and tidal recruitment are difficult to measure routinely in patients, the easily computed VILI indicator known as mechanical power also showed a strong correlation with mortality risk, highlighting its potential usefulness in designing more protective ventilation strategies for this patient group.

The online version of this article (10.1186/s12931-019-0990-5) contains supplementary material, which is available to authorized users.

• Acute respiratory distress syndrome
• Driving pressure
• Dynamic strain
• Mechanical power
• Mechanical ventilation
• Tidal recruitment

• Acute respiratory distress syndrome
• H7N9
• Influenza A virus
• Mechanical ventilation
• Prone positioning
• Recruitment maneuvers
• Viral pneumonia

In the present study, the effect of setting high airway pressure release ventilation (APRV) pressure guided by an expiratory inflection point of pressure-volume (PV) curve following lung recruitment maneuver (RM) on oxygen delivery (DO₂) in canine models of severe acute respiratory distress syndrome (ARDS) was examined. Canine models of severe ARDS were established by intravenous injection of oleic acid. After injection of sedative muscle relaxants, a PV curve plotted using the super-syringe technique, and the pressure at lower inflection point (LIP) at the inhale branch and the pressure at the point of maximum curvature (PMC) at the exhale branch were measured. The ventilation mode was biphasic positive airway pressure (BiPAP), an inspiration to expiration ratio of 1:2, and P_high 40 cm H₂O, P_low 25 cm H₂O. P_high was decreased to 30 cm H₂O after 90 sec. The dogs were randomized into 3 groups after RM, i.e., Blip group, BiPAP P_low = LIP+2 cm H₂O; Bpmc group, BiPAP P_low = PMC; and Apmc group. In the APRV group, P_high was set as PMC, with an inspiratory duration of 4 sec and expiratory duration of 0.4 sec. PMC was 18±1.4 cm H₂O, and LIP was 11±1.3 cm H₂O. Thirty seconds after RM was stabilized, it was set as 0 h. Hemodynamics, oxygenation and DO₂ were measured at 0, 1, 2 and 4 h after RM in ARDS dogs. The results demonstrated: i) cardiac index (CI) in the 3 groups, where CI was significantly decreased in the Bpmc group at 0, 1, 2 and 4 h after RM compared to prior to RM (P<0.05) as well as in the Blip and Apmc groups (P<0.05). CI in the Blip and Apmc groups was not significantly altered prior to and after RM. ii) Oxygenation at 0, 1, 2 and 4 h in the 3 groups was improved after RM and the oxygenation indices for the 3 groups at 1 and 2 h were not significantly different (P>0.05). However, the oxygenation index in the Blip group at 4 h was significantly lower than those at 0 h for the Apmc and Bpmc groups (P<0.05). Oxygenation for the Apmc group at 4 h was higher than that for the Blip and Bpmc groups (P<0.05). Oxygenation for the Bpmc group was lower than that at 0 h, although the difference was not significant (P>0.05). iii) DO₂ in at 0, 1, 2 and 4 h in the Bpmc group was significantly lower than that in the Blip and Apmc groups, and not significantly improved after RM. DO₂ in the Blip and Apmc groups after RM was improved as compard to that before RM and that in the Bpmc group. However, DO₂ at 4 h in the Blip group was significantly lower than that at 0 h and in the Apmc group (P<0.05). DO₂ at 4 h in the Apmc group was higher than that at 0 h and that in the remaining 2 groups (P<0.05). In conclusion, high APRV pressure guided at PMC of PV curve after RM significantly improved DO₂ in ARDS dogs.

• acute respiratory distress syndrome
• airway pressure release ventilation
• canine
• lung recruitment maneuver
• oxygen delivery

Selecting positive end-expiratory pressure (PEEP) during mechanical ventilation is important, as it can influence disease progression and outcome of acute respiratory distress syndrome (ARDS) patients. However, there are no well-established methods for optimizing PEEP selection due to the heterogeneity of ARDS. This research investigates the viability of titrating PEEP to minimum elastance for mechanically ventilated ARDS patients.

Ten mechanically ventilated ARDS patients from the Christchurch Hospital Intensive Care Unit were included in this study. Each patient underwent a stepwise PEEP recruitment manoeuvre. Airway pressure and flow data were recorded using a pneumotachometer. Patient-specific respiratory elastance (E_rs) and dynamic functional residual capacity (dFRC) at each PEEP level were calculated and compared. Optimal PEEP for each patient was identified by finding the minima of the PEEP-E_rs profile.

Median E_rs and dFRC over all patients and PEEP values were 32.2 cmH₂O/l [interquartile range (IQR) 25.0–45.9] and 0.42 l [IQR 0.11–0.87]. These wide ranges reflect patient heterogeneity and variable response to PEEP. The level of PEEP associated with minimum E_rs corresponds to a high change of functional residual capacity, representing the balance between recruitment and minimizing the risk of overdistension.

Monitoring patient-specific E_rs can provide clinical insight to patient-specific condition and response to PEEP settings. The level of PEEP associated with minimum-E_rs can be identified for each patient using a stepwise PEEP recruitment manoeuvre. This ‘minimum elastance PEEP’ may represent a patient-specific optimal setting during mechanical ventilation.

Australian New Zealand Clinical Trials Registry: ACTRN12611001179921.

The online version of this article (doi:10.1186/s40814-015-0006-2) contains supplementary material, which is available to authorized users.

• ARDS
• Dynamic functional residual capacity
• Mechanical ventilation
• PEEP
• Respiratory elastance

Direct comparison of the relative efficacy of different recruitment maneuvers (RMs) for patients with acute respiratory distress syndrome (ARDS) via clinical trials is difficult, due to the heterogeneity of patient populations and disease states, as well as a variety of practical issues. There is also significant uncertainty regarding the minimum values of positive end-expiratory pressure (PEEP) required to ensure maintenance of effective lung recruitment using RMs. We used patient-specific computational simulation to analyze how three different RMs act to improve physiological responses, and investigate how different levels of PEEP contribute to maintaining effective lung recruitment.

We conducted experiments on five ‘virtual’ ARDS patients using a computational simulator that reproduces static and dynamic features of a multivariable clinical dataset on the responses of individual ARDS patients to a range of ventilator inputs. Three recruitment maneuvers (sustained inflation (SI), maximal recruitment strategy (MRS) followed by a titrated PEEP, and prolonged recruitment maneuver (PRM)) were implemented and evaluated for a range of different pressure settings.

All maneuvers demonstrated improvements in gas exchange, but the extent and duration of improvement varied significantly, as did the observed mechanism of operation. Maintaining adequate post-RM levels of PEEP was seen to be crucial in avoiding cliff-edge type re-collapse of alveolar units for all maneuvers. For all five patients, the MRS exhibited the most prolonged improvement in oxygenation, and we found that a PEEP setting of 35 cm H₂O with a fixed driving pressure of 15 cm H₂O (above PEEP) was sufficient to achieve 95% recruitment. Subsequently, we found that PEEP titrated to a value of 16 cm H₂O was able to maintain 95% recruitment in all five patients.

There appears to be significant scope for reducing the peak levels of PEEP originally specified in the MRS and hence to avoid exposing the lung to unnecessarily high pressures. More generally, our study highlights the huge potential of computer simulation to assist in evaluating the efficacy of different recruitment maneuvers, in understanding their modes of operation, in optimizing RMs for individual patients, and in supporting clinicians in the rational design of improved treatment strategies.

The online version of this article (doi:10.1186/s13054-014-0723-6) contains supplementary material, which is available to authorized users.

• Evidence-Based Medicine/methods
• Humans
• Positive-Pressure Respiration/methods
• Respiratory Distress Syndrome/physiopathology
• Respiratory Distress Syndrome/therapy

• dynamic haemodynamic monitoring
• heart–lung interaction
• volume responsiveness

Mechanical ventilation (MV) is the primary form of support for acute respiratory distress syndrome (ARDS) patients. However, intra- and inter- patient-variability reduce the efficacy of general protocols. Model-based approaches to guide MV can be patient-specific. A physiological relevant minimal model and its patient-specific performance are tested to see if it meets this objective above.

Healthy anesthetized piglets weighing 24.0 kg [IQR: 21.0-29.6] underwent a step-wise PEEP increase manoeuvre from 5cmH₂O to 20cmH₂O. They were ventilated under volume control using Engström Care Station (Datex, General Electric, Finland), with pressure, flow and volume profiles recorded. ARDS was then induced using oleic acid. The data were analyzed with a Minimal Model that identifies patient-specific mean threshold opening and closing pressure (TOP and TCP), and standard deviation (SD) of these TOP and TCP distributions. The trial and use of data were approved by the Ethics Committee of the Medical Faculty of the University of Liege, Belgium.

3 of the 9 healthy piglets developed ARDS, and these data sets were included in this study. Model fitting error during inflation and deflation, in healthy or ARDS state is less than 5.0% across all subjects, indicating that the model captures the fundamental lung mechanics during PEEP increase. Mean TOP was 42.4cmH₂O [IQR: 38.2-44.6] at PEEP = 5cmH₂O and decreased with PEEP to 25.0cmH₂O [IQR: 21.5-27.1] at PEEP = 20cmH₂O. In contrast, TCP sees a reverse trend, increasing from 10.2cmH₂O [IQR: 9.0-10.4] to 19.5cmH₂O [IQR: 19.0-19.7]. Mean TOP increased from average 21.2-37.4cmH₂O to 30.4-55.2cmH₂O between healthy and ARDS subjects, reflecting the higher pressure required to recruit collapsed alveoli. Mean TCP was effectively unchanged.

The minimal model is capable of capturing physiologically relevant TOP, TCP and SD of both healthy and ARDS lungs. The model is able to track disease progression and the response to treatment.