Risk Of Ventilator-associated Lung Injury Research Articles

Pressure Control Ventilation Versus Volume Control Ventilation in Laparoscopic Surgery: A Narrative Review.

This review compares the safety and effectiveness of volume control ventilation (VCV) and pressure control ventilation (PCV) during laparoscopic surgery. Nine studies were chosen for in-depth examination following the application of stringent inclusion and exclusion criteria to the 184 publications that the literature search turned up. PCV is well-known for its capacity to preserve lower peak airway pressures during laparoscopic procedures, lowering the risk of volutrauma and barotrauma and enhancing oxygenation under these conditions of elevated intra-abdominal pressures. On the other hand, VCV guarantees a constant tidal volume and offers accurate ventilation management, both of which are essential for preserving stable carbon dioxide levels. VCV, however, may result in higher peak airway pressures, raising the risk of lung damage brought on by a ventilator. Research indicates that PCV provides better respiratory mechanics management during laparoscopic surgery, but VCV consistent tidal volume delivery is useful in some clinical situations. When choosing between PCV and VCV, the anesthesia team's experience, the demands of each patient, and the surgical circumstances should all be taken into consideration. Real-time monitoring tools and sophisticated ventilatory technology are essential for maximizing ventilation techniques. Further improving patient outcomes can be achieved by incorporating multimodal anesthesia approaches, such as the use of muscle relaxants and customized intraoperative fluid management. Muscle relaxants optimize conditions for mechanical ventilation by ensuring adequate muscle relaxation, reducing the risk of ventilator-associated lung injury, and enabling more precise control of ventilation parameters. Tailored intraoperative fluid management helps maintain optimal lung mechanics by avoiding fluid overload, which can lead to pulmonary edema and compromised gas exchange, necessitating adjustments in ventilation strategy. While both ventilation modalities can be utilized efficiently, the research suggests that PCV may be more advantageous in controlling oxygenation and airway pressures. In the dynamic and demanding world of laparoscopic surgery, ongoing research and clinical innovation are crucial to improving these tactics and guaranteeing the best possible treatment. In order to obtain the best possible patient outcomes during laparoscopic surgeries, this review emphasizes the significance of customized breathing techniques.

Abstract 12769: Association of Lung Protective Ventilation and Outcomes in Patients With Cardiogenic Shock on ECLS

Background: In Acute Respiratory Distress Syndrome, lung protective ventilation (LPV) improves patient outcomes by minimizing the risk of ventilator-associated lung injury. For patients with cardiogenic shock (CS) requiring VA-ECLS, the extracorporeal heart-lung circuit provides a unique opportunity to provide LPV. At present, there are limited data regarding optimal ventilator strategies for patients in CS on VA-ECLS. We hypothesized that CS patients on VA-ECLS who require ventilator support will have better outcomes with LPV. Methods: We queried Extracorporeal Life Support Organization (ELSO) registry for hospital admissions between 2009 and 2019 for CS patients on VA-ECLS and mechanical ventilation. Patients with multiple ECLS runs, congenital heart disease, pre-ECLS cardiac arrest, and durable mechanical circulatory support were excluded. We defined LPV as peak inspiratory pressure (PIP24)<30 cm H 2 O at 24 hours on ECLS. ELSO registry does not report tidal volume, hence, PIP24 was used as surrogate for plateau pressure. PIP24 and driving pressure (PIP24 minus PEEP24) at 24 hours (DP24) were also studied as continuous variables. Our primary outcome was survival to discharge. Multivariable analysis adjusted for baseline SAVE score, age, race, BMI, etiology of CS, intubation hours prior to ECMO and history of chronic lung disease. Results: A total of 2,226 CS patients on VA-ECLS were included of which 1904 received LPV. LPV patients had a significantly lower BMI (median 28.28 vs 31.14, p<0.001), and were less sick, as assessed by their baseline SAVE score (-1.79 vs -2.79, p=0.002). The primary outcome of survival to discharge was significantly greater in LPV cohort (47.4% vs 32.6%, p<0.001). Median PIP24 (22 vs 24, p<0.001) as well as DP24 (14.5 vs 16, p<0.001) were significantly lower in those surviving to discharge. Adjusted OR for primary outcome with LPV was 1.69 (p=0.0023). Adjusted OR for primary outcome with incremental rise in PIP24 (0.78, p=0.0003) and DP24 (0.75, p<0.0001) were also statistically significant. Conclusions: In VA-ECLS patients requiring mechanical ventilation, LPV and lower PIP and DP at 24 hours is associated with improved survival to discharge.

17 Early nasal intermittent positive pressure ventilation versus early nasal continuous positive airway pressure for preterm infants

Abstract Background Respiratory distress syndrome (RDS) is very common in preterm infants and multiple options are available to support their breathing in the early neonatal course. Non-invasive ventilation has become widely used given the opportunity to avoid intubation, mechanical ventilation and reduce the risk of ventilator-associated lung injury. Non-invasive ventilation includes nasal continuous positive airway pressure (NCPAP) and non-invasive positive pressure ventilation (NIPPV). NCPAP provides one constant pressure throughout the respiratory cycle. NIPPV additionally provides higher-pressure breaths (peak inspiratory pressure – PIP) over the constant baseline pressure. The use of these two modalities has previously been compared in a Cochrane systematic review to better comprehend the favoured option in preterm with RDS. Objectives We re-examine the risks and benefits of NIPPV versus NCPAP when implemented within the first 6 hours after birth, for preterm infants with respiratory distress in this updated Cochrane review. Design/Methods We used the criteria and standard methods of Cochrane and Cochrane Neonatal to conduct a comprehensive literature search for inclusion of all randomized, quasi-randomized trials and cross-over trials fitting our inclusion criteria. Primary endpoints are respiratory failure and the need for intubated ventilatory support during the first week of life. Secondary endpoints included chronic lung disease, length of stay (LOS), pneumothorax, and mortality. We analyzed the included trials using risk ratio (RR), risk difference and the number needed to treat for an additional beneficial outcome or an additional harmful outcome for dichotomous outcomes, and mean difference (MD) for continuous outcomes. We used the GRADE approach to assess the quality of evidence. Results In this updated systematic review, we screened 1143 studies for the title and abstract screening. 36 studies were retained for full-text review and 8 new trials were added to this update. We re-affirmed the superiority of NIPPV VS CPAP to prevent respiratory failure (risk ratio (RR) 0.62, 95% confidence interval (CI) 0.52 to 0.75), in reducing the need for intubation (risk ratio RR 0.70, CI 0.60 to 0.82), chronic lung disease (risk ratio RR 0.68, CI 0.50 to 0.92) and LOS (Mean difference -3.05 days, CI -4.92, -1.17). We did not find any difference in the mortality rate or rate of pneumothorax. For most outcomes, the certainty of evidence was graded as moderate or low. Conclusion NIPPV is superior to NCPAP as a primary respiratory support modality for preterm infants with RDS, in preventing respiratory failure and the need for intubation in the first week of life.

This Month in Anesthesiology

This Month in Anesthesiology

PEEP ADJUSTMENT UNDER LUNG ULTRASOUND CONTROL IN NEONATES WITH RESPIRATORY DISTRESS SYNDROME. A CLINICAL CASE PRESENTATION

The article describes a clinical case presentation of PEEP adjustment under lung ultrasound control in a newborn with respiratory distress syndrome during artificial respiration. Diagnostic value for B-line reduction and appearance of A-lines as predictors of lung atelectasis opening is demonstrated. The practice of low-volume lung recruitment which is achieved by functional residual capacity increasing rather than raising of inspiratory peak pressure can be considered safer as to the risk of ventilator-associated lung injury and the development of severe air leakage syndrome. In addition, the absence of significant fluctuations in the partial pressure of carbon dioxide is prognostically more positive in terms of reducing cerebral perfusion. Nevertheless, additional evidence based data needs to be collected before any further conclusions can be drawn.

Lung-Protective Ventilation Strategies for Relief from Ventilator-Associated Lung Injury in Patients Undergoing Craniotomy: A Bicenter Randomized, Parallel, and Controlled Trial.

Current evidence indicates that conventional mechanical ventilation often leads to lung inflammatory response and oxidative stress, while lung-protective ventilation (LPV) minimizes the risk of ventilator-associated lung injury (VALI). This study evaluated the effects of LPV on relief of pulmonary injury, inflammatory response, and oxidative stress among patients undergoing craniotomy. Sixty patients undergoing craniotomy received either conventional mechanical (12 mL/kg tidal volume [VT] and 0 cm H2O positive end-expiratory pressure [PEEP]; CV group) or protective lung (6 mL/kg VT and 10 cm H2O PEEP; PV group) ventilation. Hemodynamic variables, lung function indexes, and inflammatory and oxidative stress markers were assessed. The PV group exhibited greater dynamic lung compliance and lower respiratory index than the CV group during surgery (P < 0.05). The PV group exhibited higher plasma interleukin- (IL-) 10 levels and lower plasma malondialdehyde and nitric oxide and bronchoalveolar lavage fluid, IL-6, IL-8, tumor necrosis factor-α, IL-10, malondialdehyde, nitric oxide, and superoxide dismutase levels (P < 0.05) than the CV group. There were no significant differences in hemodynamic variables, blood loss, liquid input, urine output, or duration of mechanical ventilation between the two groups (P > 0.05). Patients receiving LPV during craniotomy exhibited low perioperative inflammatory response, oxidative stress, and VALI.

Positive end-expiratory pressure titration at bedside using electrical impedance tomography in post-operative cardiac surgery patients.

Post-operative positive end-expiratory pressure (PEEP) setting to minimize the risk of ventilator-associated lung injury is still controversial. Assessment of regional ventilation distribution by electrical impedance tomography (EIT) might be superior as compared with global parameters. The aim of this prospective observational study was to compare global dynamic compliance (CRS ) with different EIT indices during a short clinical applicable descending PEEP trial. Twenty mechanically ventilated patients after elective cardiac surgery received a standard recruitment manoeuvre (RM) following descending PEEP trial in steps of 2 cmH2 O from PEEP 14 cmH2 O to 6 cmH2 O. During baseline and all PEEP steps, CRS was assessed and regional ventilation distribution was measured by means of EIT. The individual 'best' PEEP values for the derived EIT indices and CRS were calculated and compared. The descending PEEP trial lasted less than 10min. CRS increased after the RM and showed a maximum value at PEEP 8 cmH2 O. Ventilation distribution shifted more to dependent lung regions after RM and back to more non-dependent regions during the PEEP trial. Individual 'best' PEEP by CRS showed significantly lower values than 'best' PEEP by ventilation distribution measured with EIT indices. During a short descending PEEP trial at bedside, EIT is capable of following the status of regional ventilation distribution in ventilated patients. The 'best' PEEP value identified by individual maximum CRS was lower than optimal PEEP levels as determined by means of EIT indices. EIT could help setting PEEP in post-operative ventilated patients.

Assessment of regional ventilation in acute respiratory distress syndrome by electrical impedance tomography.

Mechanical ventilation in acute respiratory distress syndrome (ARDS) incurs a risk of ventilator-associated lung injury (VALI) from inhomogeneous conditions and different properties of dependent and non-dependent lung regions at risk of atelectasis and overdistension, respectively. Electrical impedance tomography (EIT) offers regional ventilation assessment to optimise treatment with mechanical ventilation. This article provides an overview of scientific literature on the application of impedance tomography in acute respiratory distress syndrome. It also presents the results of EIT studies in different clinical situations that may be of use in implementing impedance tomography for treating ARDS.

Can computer simulators accurately represent the pathophysiology of individual COPD patients?

BackgroundComputer simulation models could play a key role in developing novel therapeutic strategies for patients with chronic obstructive pulmonary disease (COPD) if they can be shown to accurately represent the pathophysiological characteristics of individual patients.MethodsWe evaluated the capability of a computational simulator to reproduce the heterogeneous effects of COPD on alveolar mechanics as captured in a number of different patient datasets.ResultsOur results show that accurately representing the pathophysiology of individual COPD patients necessitates the use of simulation models with large numbers (up to 200) of compartments for gas exchange. The tuning of such complex simulation models ‘by hand’ to match patient data is not feasible, and thus we present an automated approach based on the use of global optimization algorithms and high-performance computing. Using this approach, we are able to achieve extremely close matches between the simulator and a range of patient data including PaO2, PaCO2, pulmonary deadspace fraction, pulmonary shunt fraction, and ventilation/perfusion (V̇/Q) curves. Using the simulator, we computed combinations of ventilator settings that optimally manage the trade-off between ensuring adequate gas exchange and minimizing the risk of ventilator-associated lung injury for an individual COPD patient.ConclusionsOur results significantly strengthen the credibility of computer simulation models as research tools for the development of novel management protocols in COPD and other pulmonary disease states.Electronic supplementary materialThe online version of this article (doi:10.1186/s40635-014-0023-0) contains supplementary material, which is available to authorized users.

Hyperpolarized gas diffusion MRI for the study of atelectasis and acute respiratory distress syndrome.

Considerable uncertainty remains about the best ventilator strategies for the mitigation of atelectasis and associated airspace stretch in patients with acute respiratory distress syndrome (ARDS). In addition to several immediate physiological effects, atelectasis increases the risk of ventilator-associated lung injury, which has been shown to significantly worsen ARDS outcomes. A number of lung imaging techniques have made substantial headway in clarifying the mechanisms of atelectasis. This paper reviews the contributions of computed tomography, positron emission tomography, and conventional MRI to understanding this phenomenon. In doing so, it also reveals several important shortcomings inherent to each of these approaches. Once these shortcomings have been made apparent, we describe how hyperpolarized (HP) gas MRI--a technique that is uniquely able to assess responses to mechanical ventilation and lung injury in peripheral airspaces--is poised to fill several of these knowledge gaps. The HP-MRI-derived apparent diffusion coefficient (ADC) quantifies the restriction of (3) He diffusion by peripheral airspaces, thereby obtaining pulmonary structural information at an extremely small scale. Lastly, this paper reports the results of a series of experiments that measured ADC in mechanically ventilated rats in order to investigate (i) the effect of atelectasis on ventilated airspaces, (ii) the relationship between positive end-expiratory pressure (PEEP), hysteresis, and the dimensions of peripheral airspaces, and (iii) the ability of PEEP and surfactant to reduce airspace dimensions after lung injury. An increase in ADC was found to be a marker of atelectasis-induced overdistension. With recruitment, higher airway pressures were shown to reduce stretch rather than worsen it. Moving forward, HP MRI has significant potential to shed further light on the atelectatic processes that occur during mechanical ventilation.

Optimization of Mechanical Ventilator Settings for Pulmonary Disease States

The selection of mechanical ventilator settings that ensure adequate oxygenation and carbon dioxide clearance while minimizing the risk of ventilator-associated lung injury (VALI) is a significant challenge for intensive-care clinicians. Current guidelines are largely based on previous experience combined with recommendations from a limited number of in vivo studies whose data are typically more applicable to populations than to individuals suffering from particular diseases of the lung. By combining validated computational models of pulmonary pathophysiology with global optimization algorithms, we generate in silico experiments to examine current practice and uncover optimal combinations of ventilator settings for individual patient and disease states. Formulating the problem as a multiobjective, multivariable constrained optimization problem, we compute settings of tidal volume, ventilation rate, inspiratory/expiratory ratio, positive end-expiratory pressure and inspired fraction of oxygen that optimally manage the tradeoffs between ensuring adequate oxygenation and carbon dioxide clearance and minimizing the risk of VALI for different pulmonary disease scenarios.

Airway pressure release ventilation in the acute respiratory distress syndrome following traumatic injury.

Respiratory insufficiency that occurs following a traumatic injury is due to both mechanical and physiological disruption of pulmonary integrity. Although an overall decrease in pulmonary compliance (Δ V/Δ P) is a component of acute lung injury (ALI) and the acute respiratory distress syndrome (ARDS)*, this may not be a homogeneous process. Changes in compliance may actually occur at varying degrees throughout the lung parenchyma in a heterogeneous fashion. Attempting to open or recruit collapsed alveoli without causing lung injury by overdistention or stretch of alveoli with more normal compliance remains a clinical challenge. Airway pressure release ventilation (APRV) is a ventilator mode that incorporates features that optimize the spectrum of alveolar mechanics present in ARDS/ALI. In the past, the focus on ventilator support was on conforming the patient to the ventilator; alternatively, APRV accommodates the patient's breathing pattern and superimposes ventilation onto a pressure framework to support spontaneous breathing, 1 - 3 and thereby conforms the ventilator to the patient. APRV differs from other modes of positive-pressure ventilation in that it delivers a continuous positive airway pressure (CPAP) that releases periodically to augment CO 2 exchange. The patient's breathing is spontaneous and unrestricted throughout the entire ventilator cycle, allowing infinite inspiratory/expiratory ratios. Studies have shown that APRV can augment ventilation with lower pulmonary artery pressures and improved efficiency compared to traditional modes of ventilatory support; these elements may reduce the risk of ventilator-associated lung injury while improving oxygenation. After a brief review of the incidence and outcome of traumatic ARDS, we will present basic concepts of ventilator management with APRV and then will address the use of APRV in the patient with respiratory failure secondary to trauma.