Low Tidal Volume Strategy Research Articles

High vs. low tidal volume and pulmonary complications in patients with cervical spinal cord injury on mechanical ventilation: systematic review.

Cervical spinal cord injury (CSCI) patients on mechanical ventilation often lack standardized guidelines for optimal ventilatory support. This study reviews existing literature to compare outcomes between high tidal volume (HTV) and low tidal volume (LTV) strategies in this unique patient population. We searched for studies published up to August 30, 2023, in five databases, following a PECO/PICO strategy. We found six studies for quantitative analysis and meta-analyzed five studies. This meta-analysis included 396 patients with CSCI and mechanical ventilation (MV), 119 patients treated with high tidal volume (HTV), and 277 with low tidal volume (LTV). This first meta-analysis incorporates the few studies that show contradictory findings. Our meta-analysis shows that there is no significant statistical difference in developing VAP between both comparison groups (HTV vs. LTV) (OR 0.46; 95% CI 0.13 to 1.66; p > 0.05; I2: 0%), nor are there differences between the presence of other pulmonary complications when treating with HTV such as acute respiratory distress syndrome (ARDS), atelectasis, onset of weaning. In patients with CSCI in MV, the use of HTV does not carry a greater risk of pneumonia compared to LTV; in turn, it is shown as a safe ventilatory strategy as it does not establish an increase in other pulmonary complications such as ARDS, atelectasis, the onset of weaning nor others associated with volutrauma. It is necessary to evaluate the role of HTV ventilation in this group of patients in primary RCT-type studies.

Comparison of limited driving pressure ventilation and low tidal volume strategies in adults with acute respiratory failure on mechanical ventilation: a randomized controlled trial.

Ventilator-induced lung injury (VILI) presents a grave risk to acute respiratory failure patients undergoing mechanical ventilation. Low tidal volume (LTV) ventilation has been advocated as a protective strategy against VILI. However, the effectiveness of limited driving pressure (plateau pressure minus positive end-expiratory pressure) remains unclear. This study evaluated the efficacy of LTV against limited driving pressure in preventing VILI in adults with respiratory failure. A single-centre, prospective, open-labelled, randomized controlled trial. This study was executed in medical intensive care units at Siriraj Hospital, Mahidol University, Bangkok, Thailand. We enrolled acute respiratory failure patients undergoing intubation and mechanical ventilation. They were randomized in a 1:1 allocation to limited driving pressure (LDP; ⩽15 cmH2O) or LTV (⩽8 mL/kg of predicted body weight). The primary outcome was the acute lung injury (ALI) score 7 days post-enrolment. From July 2019 to December 2020, 126 patients participated, with 63 each in the LDP and LTV groups. The cohorts had the mean (standard deviation) ages of 60.5 (17.6) and 60.9 (17.9) years, respectively, and they exhibited comparable baseline characteristics. The primary reasons for intubation were acute hypoxic respiratory failure (LDP 49.2%, LTV 63.5%) and shock-related respiratory failure (LDP 39.7%, LTV 30.2%). No significant difference emerged in the primary outcome: the median (interquartile range) ALI scores for LDP and LTV were 1.75 (1.00-2.67) and 1.75 (1.25-2.25), respectively (p = 0.713). Twenty-eight-day mortality rates were comparable: LDP 34.9% (22/63), LTV 31.7% (20/63), relative risk (RR) 1.08, 95% confidence interval (CI) 0.74-1.57, p = 0.705. Incidences of newly developed acute respiratory distress syndrome also aligned: LDP 14.3% (9/63), LTV 20.6% (13/63), RR 0.81, 95% CI 0.55-1.22, p = 0.348. In adults with acute respiratory failure, the efficacy of LDP and LTV in averting lung injury 7 days post-mechanical ventilation was indistinguishable. The study was registered with the ClinicalTrials.gov database (identification number NCT04035915).

Effect of a low versus intermediate tidal volume strategy on pulmonary complications in patients at risk of acute respiratory distress syndrome-a randomized clinical trial.

There is no consensus on whether invasive ventilation should use low tidal volumes (VT) to prevent lung complications in patients at risk of acute respiratory distress syndrome (ARDS). The purpose of this study is to determine if a low VT strategy is more effective than an intermediate VT strategy in preventing pulmonary complications. A randomized clinical trial was conducted in invasively ventilated patients with a lung injury prediction score (LIPS) of >4 performed in the intensive care units of 10 hospitals in Spain and one in the United States of America (USA) from 3 November 2014 to 30 August 2016. Patients were randomized to invasive ventilation using low VT (≤ 6 mL/kg predicted body weight, PBW) (N = 50) or intermediate VT (> 8 mL/kg PBW) (N = 48). The primary endpoint was the development of ARDS during the first 7 days after the initiation of invasive ventilation. Secondary endpoints included the development of pneumonia and severe atelectases; the length of intensive care unit (ICU) and hospital stay; and ICU, hospital, 28- and 90-day mortality. In total, 98 patients [67.3% male], with a median age of 65.5 years [interquartile range 55-73], were enrolled until the study was prematurely stopped because of slow recruitment and loss of equipoise caused by recent study reports. On day 7, five (11.9%) patients in the low VT group and four (9.1%) patients in the intermediate VT group had developed ARDS (risk ratio, 1.16 [95% CI, 0.62-2.17]; p = 0.735). The incidence of pneumonia and severe atelectasis was also not different between the two groups. The use of a low VT strategy did neither affect the length of ICU and hospital stay nor mortality rates. In patients at risk for ARDS, a low VT strategy did not result in a lower incidence of ARDS than an intermediate VT strategy.Clinical Trial Registration: ClinicalTrials.gov, identifier NCT02070666.

Efficacy of Higher Positive End-Expiratory Pressure Ventilation Strategy in Patients With Acute Respiratory Distress Syndrome: A Systematic Review and Meta-Analysis.

Previous systematic reviews and meta-analyses assessing the pooled effects of higher positive end-expiratory pressure (PEEP) failed to show significantly reduced mortality in patients with acute respiratory distress syndrome (ARDS). Some new randomized controlled trials (RCTs) have been reported and an updated systematic review is needed to evaluate the use of higher PEEP in patients with ARDS.We searched MEDLINE, Cochrane Central Register of Controlled Trials (CENTRAL), EMBASE, Cumulative Index to Nursing and Allied Health Literature (CINAHL), Igaku-Chuo-Zasshi, ICTRP, the National Institute of Health Clinical Trials Register, and the reference list of recent guidelines. We included RCTs to compare the higher PEEP ventilation strategy with the lower strategy in patients with ARDS. Two authors independently assessed the eligibility of the studies and extracted the data. The primary outcomes were 28-day mortality. The GRADE (Grading of Recommendations, Assessment, Development, and Evaluations) methodology was used to evaluate the certainty of the evidence.Among the 6530 screened records, 16 randomized trials involving 4150 patients were included in our meta-analysis. When comparing higher PEEP versus lower PEEP, the pooled risk ratio (RR) for 28-day mortality was 0.85 (15 studies, n=4108, 95% CI 0.72 to 1.00, I2=58%, low certainty of evidence). Subgroup analysis by study participants with a low tidal volume (LTV) strategy showed an interaction (P for interaction, 0.001).Our study showed that in patients with ARDS, the use of higher PEEP did not significantly reduce 28-day mortality compared to the use of lower PEEP.

Intraoperative protective lung ventilation strategies in patients with morbid obesity.

ABSTRACTPostoperative pulmonary complications (PPCs) occur frequently and are associated with a prolonged hospital stay, increased mortality, and high costs. Patients with morbid obesity are at higher risk of perioperative complications, in particular associated with those related to respiratory function. One of the most prominent concerns of the anesthesiologists while taking care of the patient with obesity in the perioperative setting should be the status of the lung and delivery of mechanical ventilation as its strategy affects clinical outcomes. Negative effects of mechanical ventilation on the respiratory system known as ventilator-induced lung injury include barotrauma, volutrauma, and atelectrauma. However, the optimal regimen of mechanical ventilation still remains a matter of debate. While low tidal volume (VT) strategy has become a widely accepted standard of care, the protective role of PEEP and recruitment maneuvers is less clear. This review focuses on the pathophysiology of respiratory function in patients with morbid obesity, the effects of mechanical ventilation on the lungs, and optimal intraoperative strategy based on the current state of knowledge.

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.

Comparison of Changes in PPV Using a Tidal Volume Challenge with a Passive Leg Raising Test to Predict Fluid Responsiveness in Patients Ventilated Using Low Tidal Volume.

BackgroundTidal volume challenge pulse pressure variation (TVC-PPV) is considered one of the recent reliable dynamic indices of fluid responsiveness (FR); also, passive leg raising (PLR)-induced changes in cardiac output (CO) detected by echocardiography are considered a reliable reversible self-fluid challenge test; many patients share eligibility for both tests.ObjectivesThe study aimed to compare the sensitivity and specificity of both tests for the prediction of FR in mechanically ventilated patients with hemodynamic instability.MethodsWe studied 46 patients. Hemodynamic parameters including PPV and CO (detected by velocity time integral (VTI) using echocardiography) recorded at tidal volume (VT) of 6 mL/kg/ideal body weight (IBW) in semi-recumbent position then recorded again after one-minute increase in TV from 6 to 8 mL/kg/IBW then recorded with PLR at TV of 6 mL/kg/IBW and finally with actual volume expansion in semi-recumbent position by 4 ml/kg bolus of crystalloid solution to define actual responders with increase of cardiac output of 15% or more.ResultsSixteen patients were responders, and thirty patients were nonresponders; responders had significant increase in PPV with TVC 6 to 8 ml/kg/IBW with best cutoff value of 3.5 with a sensitivity of 93.8% and a specificity of 93.9%. PLR test-induced changes in CO had a sensitivity of 93.9% and a specificity of 86.7% with statistically best cutoff value of 6.5% increase in CO, but sensitivity was 75% at cutoff value of 10% increase in CO. Other parameters like PPV, PPV changes with PLR test, and PPV changes with fluid expansion were less sensitive indicators.ConclusionFR in patients with hemodynamic instability and mechanically ventilated with low tidal volume strategy can be efficiently predicted when PPV increases more than 3.5 with tidal volume challenge and when PLR induces 6.5% increase in CO monitored through VTI method by Doppler echocardiography, and both tests are equally reliable.How to cite this articleElsayed AI, Selim KAW, Zaghla HE, Mowafy HE, Fakher MA. Comparison of Changes in PPV Using a Tidal Volume Challenge with a Passive Leg Raising Test to Predict Fluid Responsiveness in Patients Ventilated Using Low Tidal Volume. Indian J Crit Care Med 2021;25(6):685–690.

Açık Kalp Cerrahisinde Düşük Tidal Volüm Ventilasyon: 8 ml/kg ve 6 ml/kg Tidal volümden Hangisi Daha İyi?

Objective: To compare the outcomes of 6m/kg vs. 8 ml/kg tidal volume in the lung protective ventilation - low tidal volume strategy in coronary artery bypass grafting operation. Methods: Thirty-two patients enrolled in a randomized, single-center, prospective study were divided into two groups. The outcomes of 6m/kg vs. 8 ml/kg were compared. Arterial blood pressures, heart rate, central venous pressure, expired tidal volume, respiratory frequency, the alveolar minute ventilation, the inspiratory time, static compliance, peak airway pressure, plateau pressure, driving pressure, arterial blood gas data and PaCO2-EtCO2 difference were recorded at T1 (15 min. prior to CPB), T2 (15 min. following the termination of cardio pulmonary bypass), and T3 times (at the end of the surgery). PaO2/FiO2 ratio was recorded at T1, T2 and T3 and 6th (T4) and 12th hours (T5) after extubation. Results: In Group 6ml/kg, extubation time and length of stay in the intensive care unit were significantly longer (p<0.001, p=0.001, respectively). Discharge times were similar in both groups. In group 6ml/kg, PaCO2 was high at all times (T1, T2, T3; p=0.002, p=0.004, p=0.001, respectively), Hemodynamic changes had a similar course in both groups, in Group 6ml/kg. The PaO2/FiO2 ratio was significantly higher in Group 8ml/kg at T2 (p=0.009) and similar at other times. Conclusion: Mechanical ventilation with a low tidal volume strategy with 8 ml/kg has more favorable outcomes by considering the shorter extubation time and length of stay in the intensive care unit comparing with 6 ml/kg.

Implementation of acute respiratory distress syndrome treatment strategies by critical care physicians in Liaoning Province: a multi-center investigation

To investigate the implementation of the currently recognized and effective treatment strategies for acute respiratory distress syndrome (ARDS) in Liaoning Province in order to improve the clinical implementation of ARDS treatment strategies. From January 1st to January 31st, 2019, doctors from the department of critical care medicine of the First Affiliated Hospital of China Medical University applied the self-designed Questionnaire about critical care physicians' clinical behaviors on ARDS patients to investigate the critical care physicians in all levels of hospitals in Liaoning Province. The questionnaire was sent and retrieved in the form of Email and WeChat applet. The investigation included physicians' basic information and treatment behavior. The treatment strategies included 25 multiple-choice questions, such as ventilator mode, sedation, analgesia and other related questions about ARDS patients with different severities. Totally 160 questionnaires were retrieved in this study, 14 questionnaires with a completion rate of less than 75% were excluded, and there were totally 146 questionnaires finally accepted. The surveyed 146 critical care physicians came from 28 hospitals in Liaoning Province, and the majority were 25-44 years old (80.2%) and attending physicians (34.2%). Years of medical service and intensive care units (ICU) service were mainly less than 5 years (31.5% and 43.9%, respectively). 88.4% of the hospitals were Grade III Level A hospitals, 89.0% were teaching hospitals, and 48.6% had more than 2 000 beds. The number of ICU beds was mainly 10-19 (39.0%), and only 4.1% had over 60 beds. 77.2% of the hospitals did not have respiratory therapists, however there were 19.1% of the hospitals owning 1-4 respiratory therapists. Most physicians had positive implementation of currently recognized effective treatment strategies in ARDS, yet some of them still depended on the severity of the patients. More than 80% of the physicians monitored the peak pressure, plateau pressure and respiratory compliance of all ARDS patients (no significant differences between severity of illness). The control range of above monitoring indicators would be changed with patients' condition. Half of the physicians controlled the peak pressure of mild ARDS patients at 20-29 cmH2O (1 cmH2O = 0.098 kPa) and plateau pressure at 15-34 cmH2O. However, for severe patients, more physicians chose peak pressure and plateau pressure of 30-39 cmH2O (67.8%) and 25-34 cmH2O (70.3%) respectively. For the moderate to severe ARDS patients, majority of the physicians had positive implementation in improving oxygenation, choosing positive end expiratory pressure (PEEP) and applying low tidal volume (LVT) strategy, while conservative method was put toward on mild patients. For severe patients, 97.3% of the physicians preferred immediate invasive mechanical ventilation, 92.4% ensured tidal volume below 8 mL/kg, 61.7% chose PEEP of 15-20 cmH2O, 97.8% applied deep sedation, 82.5% chose neuromuscular blocking agents, 82.3% preferred to prone positioning ventilation, and 84.3% of the physicians chose to use hormone therapy. For mild ARDS patients, 77.2% of the physicians chose LVT strategy and mostly control PEEP at 5-9 cmH2O. There were three main reasons that affect the physicians' implementation. The first reason was physicians' subjective attitude, the second was lacking in execution conditions, and the third was physicians' considering of the complications. Most critical care physicians in Liaoning Province had positive implementation toward the currently recognized effective ARDS treatment strategies, but a few performed poorly. According to the reasons that affected the physicians' treatment behaviors, it is necessary to strengthen physicians' awareness of treatment, apply strict training, standardize the clinical implementation of effective treatment strategies, and then improve the prognosis of ARDS patients.

Mechanical Ventilation and Predictors of In-Hospital Mortality in Fibrotic Interstitial Lung Disease With Acute Respiratory Failure: A Cohort Analysis Through the Paradigm of Acute Respiratory Distress Syndrome.

Prior studies report significant mortality in fibrotic interstitial lung disease patients undergoing mechanical ventilation. Little is known about baseline characteristics or ventilator strategies that might improve outcomes. We analyzed the ventilator characteristics of a large cohort of fibrotic interstitial lung disease patients from the perspective of an acute respiratory distress syndrome paradigm to see if any specific mechanical ventilation strategies might improve in-hospital mortality. Retrospective cohort study. Single-center, multihospital medical ICUs. Consecutive fibrotic interstitial lung disease patients who experienced mechanical ventilation for acute respiratory failure. Interstitial lung disease characteristics, demographics, and ventilator variables were analyzed for univariable and multivariable predictors of in-hospital mortality, adjusted for confounding with an a priori causation model. A total of 111 patients accounted for 114 admissions. Idiopathic pulmonary fibrosis comprised 34% with idiopathic acute exacerbation (65%) being the most common admission type. Ninety-five percent were initiated on mandatory volume-control ventilation with only 50% achieving a low tidal volume strategy (plateau pressure ≤ 30 cm H2O) within 3 hours of intubation. Unadjusted clinical predictors of in-hospital mortality included age (unit odds ratio, 1.05; 1.01-1.10; p = 0.015), time from admission to intubation (hr) (unit odds ratio, 1.01; 1.01-1.03; p = 0.017), and use of paralytics (relative risk, 1.54; 1.26-1.90, p < 0.001). Adjusted mechanical ventilation-related predictors of in-hospital mortality included achieving early targeted plateau pressures (odds ratio, 0.23; 0.07-0.76; p = 0.016), PaO2/FIO2 ratio at 3 (unit odds ratio, 0.98; 0.96-0.99, p = 0.002) and 48 hours (unit odds ratio, 0.98; 0.97-0.99, p = 0.018), initial mean airway pressure (unit odds ratio, 1.13; 1.02-1.28, p = 0.019), and total net fluid status (mL) (unit odds ratio, 1.01; 1.001-1.02, p = 0.0001). Several factors predict in-hospital mortality in fibrotic interstitial lung disease-associated mechanical ventilation when viewed through an acute respiratory distress syndrome model. Further research is needed to refine strategies that may perhaps improve survival if mechanical ventilation is pursued in this set of patients.

Respiratory System: Physiology of Mechanical Ventilation

Airway and ventilatory management are mandatory skills for the critical care surgeon. Identifying and correctly managing a patient’s airway is the first step followed by correcting any oxygenation or ventilation deliver deficits. Mechanical ventilation with positive pressure has multiple physiologic effects that must be completely understood in a complex critically ill patient. Invasive and non-invasive modalities may be used to aid in achieving these goals. Further strategies such as using low tidal volume, adequate PEEP, and rescue strategies are important in patients with ARDS. Weaning from the ventilator as soon as able is an important consideration to improve outcomes, The subsequent chapter reviews airway management and the physiologic aspects of mechanical ventilation to aid in decision-making when caring for the critically ill patient with deficits in oxygenation or ventilation. This review 5 figures, 2 tables, and 41 references. Key Words: airway management, mechanical ventilation, invasive ventilation, non-invasive ventilation, tracheostomy, Acute Respiratory Distress Syndrome (ARDS), positive pressure ventilation, oxygenation

Respiratory System: Physiology of Mechanical Ventilation

Airway and ventilatory management are mandatory skills for the critical care surgeon. Identifying and correctly managing a patient’s airway is the first step followed by correcting any oxygenation or ventilation deliver deficits. Mechanical ventilation with positive pressure has multiple physiologic effects that must be completely understood in a complex critically ill patient. Invasive and non-invasive modalities may be used to aid in achieving these goals. Further strategies such as using low tidal volume, adequate PEEP, and rescue strategies are important in patients with ARDS. Weaning from the ventilator as soon as able is an important consideration to improve outcomes, The subsequent chapter reviews airway management and the physiologic aspects of mechanical ventilation to aid in decision-making when caring for the critically ill patient with deficits in oxygenation or ventilation. This review 5 figures, 2 tables, and 41 references. Key Words: airway management, mechanical ventilation, invasive ventilation, non-invasive ventilation, tracheostomy, Acute Respiratory Distress Syndrome (ARDS), positive pressure ventilation, oxygenation

Respiratory System: Physiology of Mechanical Ventilation

Airway and ventilatory management are mandatory skills for the critical care surgeon. Identifying and correctly managing a patient’s airway is the first step followed by correcting any oxygenation or ventilation deliver deficits. Mechanical ventilation with positive pressure has multiple physiologic effects that must be completely understood in a complex critically ill patient. Invasive and non-invasive modalities may be used to aid in achieving these goals. Further strategies such as using low tidal volume, adequate PEEP, and rescue strategies are important in patients with ARDS. Weaning from the ventilator as soon as able is an important consideration to improve outcomes, The subsequent chapter reviews airway management and the physiologic aspects of mechanical ventilation to aid in decision-making when caring for the critically ill patient with deficits in oxygenation or ventilation. This review 5 figures, 2 tables, and 41 references. Key Words: airway management, mechanical ventilation, invasive ventilation, non-invasive ventilation, tracheostomy, Acute Respiratory Distress Syndrome (ARDS), positive pressure ventilation, oxygenation

Respiratory System: Physiology of Mechanical Ventilation

Airway and ventilatory management are mandatory skills for the critical care surgeon. Identifying and correctly managing a patient’s airway is the first step followed by correcting any oxygenation or ventilation deliver deficits. Mechanical ventilation with positive pressure has multiple physiologic effects that must be completely understood in a complex critically ill patient. Invasive and non-invasive modalities may be used to aid in achieving these goals. Further strategies such as using low tidal volume, adequate PEEP, and rescue strategies are important in patients with ARDS. Weaning from the ventilator as soon as able is an important consideration to improve outcomes, The subsequent chapter reviews airway management and the physiologic aspects of mechanical ventilation to aid in decision-making when caring for the critically ill patient with deficits in oxygenation or ventilation. This review 5 figures, 2 tables, and 41 references. Key Words: airway management, mechanical ventilation, invasive ventilation, non-invasive ventilation, tracheostomy, Acute Respiratory Distress Syndrome (ARDS), positive pressure ventilation, oxygenation

ECMO in severe acute respiratory distress syndrome

As summarised last year in a Comment in The Lancet Respiratory Medicine,1 four randomised trials2–5 of extracorporeal membrane oxygenation (ECMO) have been done in patients with severe acute respiratory distress syndrome (ARDS) in the past 40 years. The 1979 and 1994 trials2,3 did not include a lung-protective ventilation strategy for patients in their control groups because they were done before publication of the US National Heart, Lung, and Blood Institute's ARDS Network-sponsored trial,6 which was published in 2000 and showed a major reduction in mortality with a low tidal volume and plateau pressure limited ventilation strategy.

Epidemiology, lung mechanics and outcomes of ARDS: A comparison between pregnant and non-pregnant subjects

PurposeWe describe the epidemiology, lung mechanics and outcomes of acute respiratory distress syndrome (ARDS) complicating pregnancy. We also compare the outcomes of ARDS in pregnant and non-pregnant females. MethodsRetrospective observational study of all women admitted with ARDS. Results211 women with ARDS were admitted, which included 27 (12.8%) pregnant subjects. All were ventilated with a low tidal volume strategy. Most pregnant females presented during the third trimester. There was no difference in the lung compliance, the applied PEEP and the plateau pressures across trimesters. The pregnant females had a lower median age (25 [22-28] vs. 32 [22–42] years, p = 0.003), higher proportion of severe ARDS (40.8% vs. 10.3%, p < 0.0001), and higher driving pressure (18.2 vs. 15.5 cm H2O, p = 0.03) compared to non-pregnant females. The maternal (18.5%) and perinatal (37%) mortality was high. However, the mortality was not different between pregnant and non-pregnant subjects with ARDS. On a multivariate logistic regression analysis, the baseline APACHE II score, driving pressure and the delta SOFA score were independent predictors of mortality. ConclusionsARDS complicating pregnancy is severe and is associated with high perinatal mortality. However, the outcomes of ARDS in pregnant females were similar to non-pregnant females.

Effect of a Low vs Intermediate Tidal Volume Strategy on Ventilator-Free Days in Intensive Care Unit Patients Without ARDS

It remains uncertain whether invasive ventilation should use low tidal volumes in critically ill patients without acute respiratory distress syndrome (ARDS). To determine whether a low tidal volume ventilation strategy is more effective than an intermediate tidal volume strategy. A randomized clinical trial, conducted from September 1, 2014, through August 20, 2017, including patients without ARDS expected to not be extubated within 24 hours after start of ventilation from 6 intensive care units in the Netherlands. Invasive ventilation using low tidal volumes (n = 477) or intermediate tidal volumes (n = 484). The primary outcome was the number of ventilator-free days and alive at day 28. Secondary outcomes included length of ICU and hospital stay; ICU, hospital, and 28- and 90-day mortality; and development of ARDS, pneumonia, severe atelectasis, or pneumothorax. In total, 961 patients (65% male), with a median age of 68 years (interquartile range [IQR], 59-76), were enrolled. At day 28, 475 patients in the low tidal volume group had a median of 21 ventilator-free days (IQR, 0-26), and 480 patients in the intermediate tidal volume group had a median of 21 ventilator-free days (IQR, 0-26) (mean difference, -0.27 [95% CI, -1.74 to 1.19]; P = .71). There was no significant difference in ICU (median, 6 vs 6 days; 0.39 [-1.09 to 1.89]; P = .58) and hospital (median, 14 vs 15 days; -0.60 [-3.52 to 2.31]; P = .68) length of stay or 28-day (34.9% vs 32.1%; hazard ratio [HR], 1.12 [0.90 to 1.40]; P = .30) and 90-day (39.1% vs 37.8%; HR, 1.07 [0.87 to 1.31]; P = .54) mortality. There was no significant difference in the percentage of patients developing the following adverse events: ARDS (3.8% vs 5.0%; risk ratio [RR], 0.86 [0.59 to 1.24]; P = .38), pneumonia (4.2% vs 3.7%; RR, 1.07 [0.78 to 1.47]; P = .67), severe atelectasis (11.4% vs 11.2%; RR, 1.00 [0.81 to 1.23]; P = .94), and pneumothorax (1.8% vs 1.3%; RR, 1.16 [0.73 to 1.84]; P = .55). In patients in the ICU without ARDS who were expected not to be extubated within 24 hours of randomization, a low tidal volume strategy did not result in a greater number of ventilator-free days than an intermediate tidal volume strategy. ClinicalTrials.gov Identifier: NCT02153294.

Preemptive Mechanical Ventilation Based on Dynamic Physiology in the Alveolar Microenvironment: Novel Considerations of Time-Dependent Properties of the Respiratory System.

The acute respiratory distress syndrome (ARDS) remains a serious clinical problem with the current treatment being supportive in the form of mechanical ventilation. However, mechanical ventilation can be a double-edged sword; if set properly, it can significantly reduce ARDS associated mortality but if set improperly it can have unintended consequences causing a secondary ventilator induced lung injury (VILI). The hallmark of ARDS pathology is a heterogeneous lung injury, which predisposes the lung to a secondary VILI. The current standard of care approach is to wait until ARDS is well established and then apply a low tidal volume (LVt) strategy to avoid over-distending the remaining normal lung. However, even with the use of LVt strategy, the mortality of ARDS remains unacceptably high at ~40%. In this review, we analyze the lung pathophysiology associated with ARDS that renders the lung highly vulnerable to a secondary VILI. The current standard of care LVt strategy is critiqued as well as new strategies used in combination with LVt to protect the lung. Using the current understanding of alveolar mechanics (i.e. the dynamic change in alveolar size and shape with tidal ventilation) we provide a rationale for why the current protective ventilation strategies have not further reduced ARDS mortality. New strategies of protective ventilation based on dynamic physiology in the micro-environment (i.e. alveoli and alveolar ducts) are discussed. Current evidence suggests that alveolar inflation and deflation is viscoelastic in nature, with a fast and slow phase in both alveolar recruitment and collapse. Using this knowledge, a ventilation strategy with a prolonged time at inspiration would recruit alveoli and a brief release time at expiration would prevent alveolar collapse, converting heterogeneous to homogeneous lung inflation significantly reducing ARDS incidence and mortality.

Ventilator management for acute respiratory distress syndrome associated with avian influenza A (H7N9) virus infection: A case series.

Data on the mechanical ventilation (MV) characteristics and radiologic features for the cases with H7N9-induced ARDS were still lacking. We describe the MV characteristics and radiologic features of adult patients with ARDS due to microbiologically confirmed H7N9 admitted to our ICU over a 3-month period. Eight patients (mean age 57.38±16.75; 5 male) were diagnosed with H7N9 in the first quarter of 2014. All developed respiratory failure complicated by acute respiratory distress syndrome (ARDS), which required MV in ICU. The baseline APACHE II and SOFA score was 11.77±6.32 and 7.71±3.12. The overall CT scores of the patients was 247.68±34.28 and the range of CT scores was 196.3-294.7. The average MV days was 14.63±6.14, and 4 patients required additional rescue therapies for refractory hypoxemia. Despite these measures, 3 patients died. In H7N9-infected patients with ARDS, low tidal volume strategy was the conventional mode. RM as one of rescue therapies to refractory hypoxemia in these patients with serious architectural distortion and high CT scores, which could cause further lung damage, may induce bad outcomes and requires serious consideration. Prone ventilation may improve mortality, and should be performed at the early stage of the disease, not as a rescue therapy.

Recruitment and titrated positive end-expiratory pressure in acute respiratory distress—have we reached the ceiling?

Acute respiratory distress (ARDS) is a serious medical condition having significant mortality, the management of which hinges primarily on appropriate ventilator management. The different aspects of management have been a matter of intense research over the last several decades which have led to better understanding of the disease process as well as periodic modifications in ventilator strategies. Over the years, the two aspects of ventilator strategies that have been accepted as standard-of-care are low tidal volume (LTV) strategy and suitable high positive end expiratory pressure (PEEP) ventilation. However, the exact “quantum” of PEEP has been ardently debated and has not been yet determined even after scores of trials. The evidence in favour of either an arbitrary “higher” or “lower” PEEP has been largely equivocal.