Driving pressure and long-term outcomes in moderate/severe acute respiratory distress syndrome

Neuroleptics used in critical COVID associated with moderate-severe dyspnea after hospital discharge

Dyspnea is a prominent symptom in patients with long COVID due to its high prevalence and significant clinical impact. However, the influence of commonly used medications in critically ill patients on long-term dyspnea remains unclear. This study aimed to identify risk factors and assess the impacts associated with moderate to severe dyspnea in COVID-19 survivors. This study evaluated patients admitted to a university hospital between April 2020 and April 2021. Data were collected on clinical preconditions, hospital and ICU stays, and the use of corticosteroids, neuroleptics, neuromuscular blockers, midazolam, fentanyl, and noradrenaline. Post-discharge evaluations were conducted at 1 and 12 months, assessing dyspnea, frailty, quality of life, functional capacity, anxiety, and depression. Descriptive statistics, including frequencies and percentages, were used, and logistic regression analysis was performed to identify factors associated with moderate to severe dyspnea at 1 and 12 months post-discharge. Statistical significance was defined as P < 0.05. A total of 100 patients were prospectively included in the study; all underwent the 1-month evaluation, and 63 completed the 12-month evaluation. Limiting dyspnea, defined as an mMRC score > 1, was observed in 56.6% of patients at 1 month and 33.9% at 12 months post-discharge. Independent factors associated with limiting dyspnea at 1 month included the total dose of neuroleptics administered during hospitalization and the presence of pre-existing comorbidities. The use of corticosteroids, neuromuscular blockers, midazolam, fentanyl, and noradrenaline showed no significant association with limiting dyspnea. Dyspnea at 1 month post-discharge was an independent risk factor for the persistence of limiting dyspnea at 12 months. Patients with limiting dyspnea at 12 months exhibited higher levels of depression, anxiety, and frailty, alongside reduced quality of life and functionality. Patients with severe COVID-19 exhibit a high prevalence of limiting dyspnea in the long term. The total dose of neuroleptics administered during hospitalization and the presence of comorbidities were independently associated with limiting dyspnea after discharge. At 12 months post-discharge, individuals with persistent limiting dyspnea frequently demonstrated additional physical and mental health impairments, underscoring the need for comprehensive evaluation and management to mitigate the burden of long-term disabilities.

Long-term assessment of functional capacity, muscle function, lung function, and quality of life in survivors of ventilator-associated pneumonia

Background and objective

The many patients who develop ventilator-associated pneumonia (VAP) have generated numerous VAP survivors who are not followed up in the long term. This study aimed, primarily, to evaluate the long-term functional capacity, as measured using the Glittre-ADL test (TGlittre), of VAP survivors and, secondarily, to calculate the correlations of TGlittre with muscle and lung function.

Methods

This cross-sectional study evaluated 30 VAP survivors 10 months after discharge from the intensive care unit. The participants underwent the following assessments: TGlittre; respiratory muscle strength; handgrip strength (HGS); spirometry; Functional Assessment of Chronic Therapy (FACIT-F); and Short Form-36 (SF-36).

Results

The median TGlittre time was 95 (81-130)% of predicted, and 30 % of the participants performed poorly on TGlittre. One-third of the participants had abnormal spirometry results. TGlittre time was correlated with weight (rs = -0.412, P = 0.023), body index mass (BMI, rs = -0.400, P = 0.029), forced vital capacity (FVC, rs = -0.401, P = 0.030), HGS (rs = -0.571, P = 0.0009), FACIT-F score (rs = -0.405, P = 0.026), and different SF-36 domain scores. Participants who returned to work had a shorter TGlittre time than those who did not (89 (69-104) vs. 129 (102-183)% predicted). Multiple linear regression indicated that FVC and BMI explained 39 % of TGlittre variability.

Conclusion

VAP survivors had suboptimal functional capacity, low lung function, and general fatigue 10 months after discharge. The longer the TGlittre time was, the worse the lung function, muscle function, general fatigue, and quality of life were and the less likely the patient was to have returned to work.

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

BACKGROUND

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.

OBJECTIVES

This study evaluated the efficacy of LTV against limited driving pressure in preventing VILI in adults with respiratory failure.

DESIGN

A single-centre, prospective, open-labelled, randomized controlled trial.

METHODS

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.

RESULTS

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.

CONCLUSIONS

In adults with acute respiratory failure, the efficacy of LDP and LTV in averting lung injury 7 days post-mechanical ventilation was indistinguishable.

CLINICAL TRIAL REGISTRATION

The study was registered with the ClinicalTrials.gov database (identification number NCT04035915).

Genomic communication via circulating extracellular vesicles and long-term health consequences of COVID-19

COVID-19 continues to affect an unprecedented number of people with the emergence of new variants posing a serious challenge to global health. There is an expansion of knowledge in understanding the pathogenesis of Coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), and the impact of the acute disease on multiple organs. In addition, growing evidence reports that the impact of COVID-19 on different organs persists long after the recovery phase of the disease, leading to long-term consequences of COVID-19. These long-term consequences involve pulmonary as well as extra-pulmonary sequelae of the disease. Noteably, recent research has shown a potential association between COVID-19 and change in the molecular cargo of extracellular vesicles (EVs). EVs are vesicles released by cells and play an important role in cell communication by transfer of bioactive molecules between cells. Emerging evidence shows a strong link between EVs and their molecular cargo, and regulation of metabolism in health and disease. This review focuses on current knowledge about EVs and their potential role in COVID-19 pathogenesis, their current and future implications as tools for biomarker and therapeutic development and their possible effects on long-term impact of COVID-19.

Static Respiratory System Compliance as a Predictor of Extubation Failure in Patients with Acute Respiratory Failure

PURPOSE

Ventilator weaning protocols rely in part on objective indices to best predict extubation failure in the critically ill. We investigated static respiratory system compliance (RC) as a predictor of extubation failure, in comparison to extubation readiness using rapid shallow breathing index (RSBI).

MATERIAL AND METHODS

This was a cross-sectional, multi-institutional study of mechanically ventilated patients admitted between 12/01/2017 and 12/01/2019. All patients older than 18 years with a documented spontaneous breathing trial and extubation trial were included. RC and RSBI were calculated prior to the extubation trial. The primary outcome was extubation failure-defined as need for reintubation within 72 h from time of extubation.

RESULTS

Of the 2263 patients, 55.8% were males with a mean age of 68 years. The population consisted mostly of Caucasians (73%) and African Americans (20.4%). 274 (12.1%) patients required reintubation within 72 h. On multivariate logistic regression after adjusting for age, sex, body mass index (BMI), admission Sequential Organ Failure Assessment (SOFA) score, number of ventilator days, and the P/F ratio on the day of extubation, RC remained the strongest predictor for extubation failure at 24 h (aOR 1.45; 95% CI 1.00-2.10) and 72 h (aOR 1.58; 95% CI 1.15-2.17). There was no significant association between RSBI and extubation failure at 24 (aOR 1.00; 95% CI 0.99-1.01) or at 72 h (aOR 1.00; 95% CI 0.99-1.01).

CONCLUSION

RC measured on the day of extubation is a promising physiological discriminant to potentially risk stratify patients with acute respiratory failure for extubation readiness. We recommend further validation studies in prospective cohorts.

Driving Pressure, Elastance, and Outcomes in a Real-World Setting: A Bi-Center Analysis of Electronic Health Record Data

Emerging evidence suggests the potential importance of inspiratory driving pressure (DP) and respiratory system elastance (E_RS) on outcomes among patients with the acute respiratory distress syndrome. Their association with outcomes among heterogeneous populations outside of a controlled clinical trial is underexplored. We used electronic health record (EHR) data to characterize the associations of DP and E_RS with clinical outcomes in a real-world heterogenous population.

DESIGN

Observational cohort study.

SETTING

Fourteen ICUs in two quaternary academic medical centers.

PATIENTS

Adult patients who received mechanical ventilation for more than 48 hours and less than 30 days.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

EHR data from 4,233 ventilated patients from 2016 to 2018 were extracted, harmonized, and merged. A minority of the analytic cohort (37%) experienced a Pao₂/Fio₂ of less than 300. A time-weighted mean exposure was calculated for ventilatory variables including tidal volume (V_T), plateau pressures (P_PLAT), DP, and E_RS. Lung-protective ventilation adherence was high (94% with V_T < 8.5 mL/kg, time-weighted mean V_T = 6. 8 mL/kg, 88% with P_PLAT ≤ 30 cm H₂O). Although time-weighted mean DP (12.2 cm H₂O) and E_RS (1.9 cm H₂O/[mL/kg]) were modest, 29% and 39% of the cohort experienced a DP greater than 15 cm H₂O or an E_RS greater than 2 cm H₂O/(mL/kg), respectively. Regression modeling with adjustment for relevant covariates determined that exposure to time-weighted mean DP (> 15 cm H₂O) was associated with increased adjusted risk of mortality and reduced adjusted ventilator-free days independent of adherence to lung-protective ventilation. Similarly, exposure to time-weighted mean E_RS greater than 2 cm H₂O/(mL/kg) was associated with increased adjusted risk of mortality.

CONCLUSIONS

Elevated DP and E_RS are associated with increased risk of mortality among ventilated patients independent of severity of illness or oxygenation impairment. EHR data can enable assessment of time-weighted ventilator variables and their association with clinical outcomes in a multicenter real-world setting.

Lung morphology impacts the association between ventilatory variables and mortality in patients with acute respiratory distress syndrome

BACKGROUND

Acute respiratory distress syndrome (ARDS) patients with different lung morphology have distinct pulmonary mechanical dysfunction and outcomes. Whether lung morphology impacts the association between ventilatory variables and mortality remains unclear. Moreover, the impact of a novel combined ventilator variable [(4×DP) + RR] on morality in ARDS patients needs external validation.

METHODS

We obtained data from the Chinese Database in Intensive Care (CDIC), which included adult ARDS patients who received invasive mechanical ventilation for at least 24 h. Patients were further classified into two groups based on lung morphology (focal and non-focal). Ventilatory variables were collected longitudinally within the first four days of ventilation. The primary outcome was 28-day mortality. Extended Cox regression models were employed to explore the interaction between lung morphology and longitudinal ventilatory variables on mortality.

FINDINGS

We included 396 ARDS patients with different lung morphology (64.1% non-focal). The overall 28-day mortality was 34.4%. Patients with non-focal lung morphology have more severe and persistent pulmonary mechanical dysfunction and higher mortality than those with focal lung morphology. Time-varying driving pressure (DP) was more significantly associated with 28-day mortality in patients with non-focal lung morphology compared to focal lung morphology patients (P for interaction = 0.0039). The impact of DP on mortality was more significant than that of respiratory rate (RR) only in patients with non-focal lung morphology. The hazard ratio (HR) of mortality for [(4×DP) + RR] was significant in patients with non-focal lung morphology (HR 1.036, 95% CI 1.027-1.045), not in patients with focal lung morphology (HR 1.019, 95% CI 0.999-1.039).

INTERPRETATION

The association between ventilator variables and mortality varied among patients with different lung morphology. [(4×DP) + RR] was only associated with mortality in patients with non-focal lung morphology. Further validation is needed.

Long-term respiratory follow-up of ICU hospitalized COVID-19 patients: Prospective cohort study

BACKGROUND

Coronavirus disease (COVID-19) survivors exhibit multisystemic alterations after hospitalization. Little is known about long-term imaging and pulmonary function of hospitalized patients intensive care unit (ICU) who survive COVID-19. We aimed to investigate long-term consequences of COVID-19 on the respiratory system of patients discharged from hospital ICU and identify risk factors associated with chest computed tomography (CT) lesion severity.

METHODS

A prospective cohort study of COVID-19 patients admitted to a tertiary hospital ICU in Brazil (March-August/2020), and followed-up six-twelve months after hospital admission. Initial assessment included: modified Medical Research Council dyspnea scale, SpO2 evaluation, forced vital capacity, and chest X-Ray. Patients with alterations in at least one of these examinations were eligible for CT and pulmonary function tests (PFTs) approximately 16 months after hospital admission. Primary outcome: CT lesion severity (fibrotic-like or non-fibrotic-like). Baseline clinical variables were used to build a machine learning model (ML) to predict the severity of CT lesion.

RESULTS

In total, 326 patients (72%) were eligible for CT and PFTs. COVID-19 CT lesions were identified in 81.8% of patients, and half of them showed mild restrictive lung impairment and impaired lung diffusion capacity. Patients with COVID-19 CT findings were stratified into two categories of lesion severity: non-fibrotic-like (50.8%-ground-glass opacities/reticulations) and fibrotic-like (49.2%-traction bronchiectasis/architectural distortion). No association between CT feature severity and altered lung diffusion or functional restrictive/obstructive patterns was found. The ML detected that male sex, ICU and invasive mechanic ventilation (IMV) period, tracheostomy and vasoactive drug need during hospitalization were predictors of CT lesion severity(sensitivity,0.78±0.02;specificity,0.79±0.01;F1-score,0.78±0.02;positive predictive rate,0.78±0.02; accuracy,0.78±0.02; and area under the curve,0.83±0.01).

CONCLUSION

ICU hospitalization due to COVID-19 led to respiratory system alterations six-twelve months after hospital admission. Male sex and critical disease acute phase, characterized by a longer ICU and IMV period, and need for tracheostomy and vasoactive drugs, were risk factors for severe CT lesions six-twelve months after hospital admission.

Ventilatory settings in the initial 72 h and their association with outcome in out-of-hospital cardiac arrest patients: a preplanned secondary analysis of the targeted hypothermia versus targeted normothermia after out-of-hospital cardiac arrest (TTM2) trial

PURPOSE

The optimal ventilatory settings in patients after cardiac arrest and their association with outcome remain unclear. The aim of this study was to describe the ventilatory settings applied in the first 72 h of mechanical ventilation in patients after out-of-hospital cardiac arrest and their association with 6-month outcomes.

METHODS

Preplanned sub-analysis of the Target Temperature Management-2 trial. Clinical outcomes were mortality and functional status (assessed by the Modified Rankin Scale) 6 months after randomization.

RESULTS

A total of 1848 patients were included (mean age 64 [Standard Deviation, SD = 14] years). At 6 months, 950 (51%) patients were alive and 898 (49%) were dead. Median tidal volume (V_T) was 7 (Interquartile range, IQR = 6.2-8.5) mL per Predicted Body Weight (PBW), positive end expiratory pressure (PEEP) was 7 (IQR = 5-9) cmH₂0, plateau pressure was 20 cmH₂0 (IQR = 17-23), driving pressure was 12 cmH₂0 (IQR = 10-15), mechanical power 16.2 J/min (IQR = 12.1-21.8), ventilatory ratio was 1.27 (IQR = 1.04-1.6), and respiratory rate was 17 breaths/minute (IQR = 14-20). Median partial pressure of oxygen was 87 mmHg (IQR = 75-105), and partial pressure of carbon dioxide was 40.5 mmHg (IQR = 36-45.7). Respiratory rate, driving pressure, and mechanical power were independently associated with 6-month mortality (omnibus p-values for their non-linear trajectories: p < 0.0001, p = 0.026, and p = 0.029, respectively). Respiratory rate and driving pressure were also independently associated with poor neurological outcome (odds ratio, OR = 1.035, 95% confidence interval, CI = 1.003-1.068, p = 0.030, and OR = 1.005, 95% CI = 1.001-1.036, p = 0.048). A composite formula calculated as [(4*driving pressure) + respiratory rate] was independently associated with mortality and poor neurological outcome.

CONCLUSIONS

Protective ventilation strategies are commonly applied in patients after cardiac arrest. Ventilator settings in the first 72 h after hospital admission, in particular driving pressure and respiratory rate, may influence 6-month outcomes.

ARDS Clinical Practice Guideline 2021

BACKGROUND

The joint committee of the Japanese Society of Intensive Care Medicine/Japanese Respiratory Society/Japanese Society of Respiratory Care Medicine on ARDS Clinical Practice Guideline has created and released the ARDS Clinical Practice Guideline 2021.

METHODS

The 2016 edition of the Clinical Practice Guideline covered clinical questions (CQs) that targeted only adults, but the present guideline includes 15 CQs for children in addition to 46 CQs for adults. As with the previous edition, we used a systematic review method with the Grading of Recommendations Assessment Development and Evaluation (GRADE) system as well as a degree of recommendation determination method. We also conducted systematic reviews that used meta-analyses of diagnostic accuracy and network meta-analyses as a new method.

RESULTS

Recommendations for adult patients with ARDS are described: we suggest against using serum C-reactive protein and procalcitonin levels to identify bacterial pneumonia as the underlying disease (GRADE 2D); we recommend limiting tidal volume to 4-8 mL/kg for mechanical ventilation (GRADE 1D); we recommend against managements targeting an excessively low SpO2 (PaO2) (GRADE 2D); we suggest against using transpulmonary pressure as a routine basis in positive end-expiratory pressure settings (GRADE 2B); we suggest implementing extracorporeal membrane oxygenation for those with severe ARDS (GRADE 2B); we suggest against using high-dose steroids (GRADE 2C); and we recommend using low-dose steroids (GRADE 1B). The recommendations for pediatric patients with ARDS are as follows: we suggest against using non-invasive respiratory support (non-invasive positive pressure ventilation/high-flow nasal cannula oxygen therapy) (GRADE 2D), we suggest placing pediatric patients with moderate ARDS in the prone position (GRADE 2D), we suggest against routinely implementing NO inhalation therapy (GRADE 2C), and we suggest against implementing daily sedation interruption for pediatric patients with respiratory failure (GRADE 2D).

CONCLUSIONS

This article is a translated summary of the full version of the ARDS Clinical Practice Guideline 2021 published in Japanese (URL: https://www.jsicm.org/publication/guideline.html ). The original text, which was written for Japanese healthcare professionals, may include different perspectives from healthcare professionals of other countries.

ARDS clinical practice guideline 2021

BACKGROUND

The joint committee of the Japanese Society of Intensive Care Medicine/Japanese Respiratory Society/Japanese Society of Respiratory Care Medicine on ARDS Clinical Practice Guideline has created and released the ARDS Clinical Practice Guideline 2021.

METHODS

The 2016 edition of the Clinical Practice Guideline covered clinical questions (CQs) that targeted only adults, but the present guideline includes 15 CQs for children in addition to 46 CQs for adults. As with the previous edition, we used a systematic review method with the Grading of Recommendations Assessment Development and Evaluation (GRADE) system as well as a degree of recommendation determination method. We also conducted systematic reviews that used meta-analyses of diagnostic accuracy and network meta-analyses as a new method.

RESULTS

Recommendations for adult patients with ARDS are described: we suggest against using serum C-reactive protein and procalcitonin levels to identify bacterial pneumonia as the underlying disease (GRADE 2D); we recommend limiting tidal volume to 4-8 mL/kg for mechanical ventilation (GRADE 1D); we recommend against managements targeting an excessively low SpO₂ (PaO₂) (GRADE 2D); we suggest against using transpulmonary pressure as a routine basis in positive end-expiratory pressure settings (GRADE 2B); we suggest implementing extracorporeal membrane oxygenation for those with severe ARDS (GRADE 2B); we suggest against using high-dose steroids (GRADE 2C); and we recommend using low-dose steroids (GRADE 1B). The recommendations for pediatric patients with ARDS are as follows: we suggest against using non-invasive respiratory support (non-invasive positive pressure ventilation/high-flow nasal cannula oxygen therapy) (GRADE 2D); we suggest placing pediatric patients with moderate ARDS in the prone position (GRADE 2D); we suggest against routinely implementing NO inhalation therapy (GRADE 2C); and we suggest against implementing daily sedation interruption for pediatric patients with respiratory failure (GRADE 2D).

CONCLUSIONS

This article is a translated summary of the full version of the ARDS Clinical Practice Guideline 2021 published in Japanese (URL: https://www.jrs.or.jp/publication/jrs_guidelines/). The original text, which was written for Japanese healthcare professionals, may include different perspectives from healthcare professionals of other countries.

Mechanical Ventilation in ARDS: Quo Vadis?

Contemplating the future should be grounded in history. The rise of post-polio ICUs was inextricably related to mechanical ventilation. Critically ill patients who developed acute respiratory failure often had "congestive atelectasis" (ie, a term used to describe ARDS prior to 1967). Initial mechanical ventilation strategies for treating this condition and others inadvertently led to ventilator-induced lung injury. Both injurious ventilation and later use of overly cautious weaning practices resulted from both limited technology and understanding of ARDS and other aspects of critical illness. The resulting misperceptions, misconceptions, and missed opportunities took decades to rectify and in some instances still persist. This suggests a reluctance to acknowledge that all therapeutic strategies reflect the historical period in which they were developed and the corresponding limited understanding of ARDS pathophysiology at that time. We are at the threshold of a revolutionary moment in critical care. The confluence of enormous clinical data production, massive computing power, advances in understanding the biomolecular and genetic aspects of critical illness, and the emergence of neural networks will have enormous impact on how critical care is practiced in the decades to come. Therefore, it is imperative we understand the long-crooked path needed to reach the era of protective ventilation in order to avoid similar mistakes moving forward. The emerging era is as difficult to fathom as our current practices and technologies were to those practicing 60 years ago. This review explores the history of mechanical ventilation in treating ARDS, describes current protective ventilation strategies, and speculates how ARDS management might look 20 years from now.

Intraoperative Protective Mechanical Ventilation in Dogs: A Randomized Clinical Trial

Objective

To evaluate gas exchange, respiratory mechanics, and hemodynamic impact of mechanical ventilation with low tidal volume (V_T) in dogs with the use of positive end-expiratory pressure (PEEP) or preceded by alveolar recruitment maneuver (ARM).

Study Design

Prospective randomized clinical trial.

Animals

Twenty-one healthy client-owned mesocephalic healthy dogs, 1-7 years old, weighing 10-20 kg, and body condition scores 4-6/9 admitted for periodontal treatment.

Methods

Isoflurane-anesthetized dogs in dorsal recumbency were ventilated until 1 h with a volume-controlled ventilation mode using 8 mL kg^-1 of V_T. The dogs were distributed in 2 groups: in the ARM group, PEEP starts in 0 cmH₂O, increasing gradually 5 cmH₂O every 3 min, until reach 15 cmH₂O and decreasing in the same steps until 5 cmH₂O, maintaining this value until the end; and PEEP group, in which the pressure 5 cmH₂O was instituted from the beginning of anesthesia and maintained the same level up to the end of the anesthesia. Cardiopulmonary, metabolic, oxygenation parameters, and respiratory mechanics were recorded after the anesthesia induction (baseline-BL), 15, 45, and 75 min after BL and during the recovery.

Results

The ARM increased the static compliance (C_st) (15 min after baseline) when compared with baseline moment (24.9 ± 5.8 mL cmH₂0^-1 vs. 20.7 ± 5.4 mL cmH₂0^-1-p = 0.0364), oxygenation index (PaO₂/FIO₂) (505.6 ± 59.2 mmHg vs. 461.2 ± 41.0 mmHg-p = 0.0453) and reduced the shunt fraction (3.4 ± 2.4% vs. 5.5 ± 1.6%-p = 0.062). In the PEEP group, no statistical differences were observed concerning the variables evaluated. At the beginning of the evaluation, the driving pressure (DP) before ARM was significantly greater than all other evaluation time points (6.9 ± 1.8 cmH₂0).

Conclusions and Clinical Relevance

The use of 8 mL kg^-1 of V_T and 5 cmH₂0 PEEP without ARM maintain adequate oxygenation and mechanical ventilation in dental surgeries for up to 1 h. The use of ARM slightly improved compliance and oxygenation during the maneuver.

Ventilation management and outcomes in out-of-hospital cardiac arrest: a protocol for a preplanned secondary analysis of the TTM2 trial

INTRODUCTION

Mechanical ventilation is a fundamental component in the management of patients post cardiac arrest. However, the ventilator settings and the gas-exchange targets used after cardiac arrest may not be optimal to minimise post-anoxic secondary brain injury. Therefore, questions remain regarding the best ventilator management in such patients.

METHODS AND ANALYSIS

This is a preplanned analysis of the international randomised controlled trial, targeted hypothermia versus targeted normothermia after out-of-hospital cardiac arrest (OHCA)-target temperature management 2 (TTM2). The primary objective is to describe ventilatory settings and gas exchange in patients who required invasive mechanical ventilation and included in the TTM2 trial. Secondary objectives include evaluating the association of ventilator settings and gas-exchange values with 6 months mortality and neurological outcome. Adult patients after an OHCA who were included in the TTM2 trial and who received invasive mechanical ventilation will be eligible for this analysis. Data collected in the TTM2 trial that will be analysed include patients' prehospital characteristics, clinical examination, ventilator settings and arterial blood gases recorded at hospital and intensive care unit (ICU) admission and daily during ICU stay.

ETHICS AND DISSEMINATION

The TTM2 study has been approved by the regional ethics committee at Lund University and by all relevant ethics boards in participating countries. No further ethical committee approval is required for this secondary analysis. Data will be disseminated to the scientific community by abstracts and by original articles submitted to peer-reviewed journals.

TRIAL REGISTRATION NUMBER

NCT02908308.

Relationship between Driving Pressure and Mortality in Ventilated Patients with Heart Failure: A Cohort Study

Background

Heart failure (HF) is a leading cause of mortality and morbidity worldwide, with an increasing incidence. Invasive ventilation is considered to be essential for patients with HF. Previous studies have shown that driving pressure is associated with mortality in acute respiratory distress syndrome (ARDS). However, the relationship between driving pressure and mortality has not yet been examined in ventilated patients with HF. We assessed the association of driving pressure and mortality in patients with HF.

Methods

We conducted a retrospective cohort study of invasive ventilated adult patients with HF from the Medical Information Mart for Intensive Care-III database. We used multivariable logistic regression models, a generalized additive model, and a two-piecewise linear regression model to show the effect of the average driving pressure within 24 h of intensive care unit admission on in-hospital mortality.

Results

Six hundred and thirty-two invasive ventilated patients with HF were enrolled. Driving pressure was independently associated with in-hospital mortality (odds ratio [OR], 1.12; 95% confidence interval [CI], 1.06–1.18; P < 0.001) after adjusted potential confounders. A nonlinear relationship was found between driving pressure and in-hospital mortality, which had a threshold around 14.27 cmH₂O. The effect sizes and CIs below and above the threshold were 0.89 (0.75 to 1.05) and 1.17 (1.07 to 1.30), respectively.

Conclusions

There was a nonlinear relationship between driving pressure and mortality in patients with HF who were ventilated for more than 48 h, and this relationship was associated with increased in-hospital mortality when the driving pressure was more than 14.27 cmH₂O.

Functional pathophysiology of SARS-CoV-2-induced acute lung injury and clinical implications

The worldwide pandemic caused by the SARS-CoV-2 virus has resulted in over 84,407,000 cases, with over 1,800,000 deaths when this paper was submitted, with comorbidities such as gender, race, age, body mass, diabetes, and hypertension greatly exacerbating mortality. This review will analyze the rapidly increasing knowledge of COVID-19-induced lung pathophysiology. Although controversial, the acute respiratory distress syndrome (ARDS) associated with COVID-19 (CARDS) seems to present as two distinct phenotypes: type L and type H. The "L" refers to low elastance, ventilation/perfusion ratio, lung weight, and recruitability, and the "H" refers to high pulmonary elastance, shunt, edema, and recruitability. However, the LUNG-SAFE (Large Observational Study to Understand the Global Impact of Severe Acute Respiratory Failure) and ESICM (European Society of Intensive Care Medicine) Trials Groups have shown that ∼13% of the mechanically ventilated non-COVID-19 ARDS patients have the type-L phenotype. Other studies have shown that CARDS and ARDS respiratory mechanics overlap and that standard ventilation strategies apply to these patients. The mechanisms causing alterations in pulmonary perfusion could be caused by some combination of 1) renin-angiotensin system dysregulation, 2) thrombosis caused by loss of endothelial barrier, 3) endothelial dysfunction causing loss of hypoxic pulmonary vasoconstriction perfusion control, and 4) hyperperfusion of collapsed lung tissue that has been directly measured and supported by a computational model. A flowchart has been constructed highlighting the need for personalized and adaptive ventilation strategies, such as the time-controlled adaptive ventilation method, to set and adjust the airway pressure release ventilation mode, which recently was shown to be effective at improving oxygenation and reducing inspiratory fraction of oxygen, vasopressors, and sedation in patients with COVID-19.

Functional independence and spirometry in adult post-intensive care unit patients

OBJECTIVE

To relate functional independence to the degree of pulmonary impairment in adult patients 3 months after discharge from the intensive care unit.

METHODS

This was a retrospective cohort study conducted in one adult intensive care unit and a multi-professional post-intensive care unit outpatient clinic of a single center. Patients admitted to the intensive care unit from January 2012 to December 2013 who underwent (3 months later) spirometry and answered the Functional Independence Measure Questionnaire were included.

RESULTS

Patients were divided into groups according to the classification of functional independence and spirometry. The study included 197 patients who were divided into greater dependence (n = 4), lower dependence (n = 12) and independent (n = 181) groups. Comparing the three groups, regarding the classification of the Functional Independence Measure, patients with greater dependence had higher Acute Physiology and Chronic Health Evaluation II and Sequential Organ Failure Assessment values at intensive care unit admission with more advanced age, more days on mechanical ventilation, and longer stay in the intensive care unit and hospital. The majority of patients presented with pulmonary impairment, which was the obstructive pattern observed most frequently. When comparing functional independence with pulmonary function, it was observed that the lower the functional status, the worse the pulmonary function, with a significant difference being observed in peak expiratory flow (p = 0.030).

CONCLUSION

The majority of patients who returned to the outpatient clinic 3 months after discharge had good functional status but did present with pulmonary impairment, which is related to the degree of functional dependence.

Lung Mechanics of Mechanically Ventilated Patients With COVID-19: Analytics With High-Granularity Ventilator Waveform Data

Background: Lung mechanics during invasive mechanical ventilation (IMV) for both prognostic and therapeutic implications; however, the full trajectory lung mechanics has never been described for novel coronavirus disease 2019 (COVID-19) patients requiring IMV. The study aimed to describe the full trajectory of lung mechanics of mechanically ventilated COVID-19 patients. The clinical and ventilator setting that can influence patient-ventilator asynchrony (PVA) and compliance were explored. Post-extubation spirometry test was performed to assess the pulmonary function after COVID-19 induced ARDS. Methods: This was a retrospective study conducted in a tertiary care hospital. All patients with IMV due to COVID-19 induced ARDS were included. High-granularity ventilator waveforms were analyzed with deep learning algorithm to obtain PVAs. Asynchrony index (AI) was calculated as the number of asynchronous events divided by the number of ventilator cycles and wasted efforts. Mortality was recorded as the vital status on hospital discharge. Results: A total of 3,923,450 respiratory cycles in 2,778 h were analyzed (average: 24 cycles/min) for seven patients. Higher plateau pressure (Coefficient: -0.90; 95% CI: -1.02 to -0.78) and neuromuscular blockades (Coefficient: -6.54; 95% CI: -9.92 to -3.16) were associated with lower AI. Survivors showed increasing compliance over time, whereas non-survivors showed persistently low compliance. Recruitment maneuver was not able to improve lung compliance. Patients were on supine position in 1,422 h (51%), followed by prone positioning (499 h, 18%), left positioning (453 h, 16%), and right positioning (404 h, 15%). As compared with supine positioning, prone positioning was associated with 2.31 ml/cmH2O (95% CI: 1.75 to 2.86; p < 0.001) increase in lung compliance. Spirometry tests showed that pulmonary functions were reduced to one third of the predicted values after extubation. Conclusions: The study for the first time described full trajectory of lung mechanics of patients with COVID-19. The result showed that prone positioning was associated with improved compliance; higher plateau pressure and use of neuromuscular blockades were associated with lower risk of AI.

PEEP guided by electrical impedance tomography during one-lung ventilation in elderly patients undergoing thoracoscopic surgery

Background

To examine the influence of positive end-expiratory pressure (PEEP) settings on lung mechanics and oxygenation in elderly patients undergoing thoracoscopic surgery.

Methods

One hundred patients aged >65 years were randomly allocated into either the PEEP₅ or the electrical impedance tomography (EIT) group (PEEP_EIT). Each group underwent volume-controlled ventilation (tidal volume 6 mL/kg predicted body weight) with the PEEP either fixed at 5 cmH₂O or set at an individualized EIT setting. The primary endpoint was the ratio of the arterial oxygen partial pressure to the fractional inspired oxygen (PaO₂/FiO₂). The secondary endpoints included the driving pressure, and dynamic respiratory system compliance (C_dyn). Other outcomes, such as the mean airway pressure (P_mean), mean arterial pressure (MAP), lung complications and the length of hospital stay were explored.

Results

The optimal PEEP set by EIT was significantly higher (range from 9-13 cmH₂O) than the fixed PEEP. PaO₂/FiO₂ was 47 mmHg higher (95% CI: 7-86 mmHg; P=0.021), C_dyn was 4.3 mL/cmH₂O higher (95% CI: 2.1-6.7 cmH₂O; P<0.001), and the driving pressure was 3.7 cmH₂O lower (95% CI: 2.2-5.1 mmH₂O; P<0.001) at 0.5 h during one-lung ventilation (OLV) in the PEEP_EIT group than in the PEEP₅ group. At 1 h during OLV, PaO₂/FiO₂ was 93 mmHg higher (95% CI: 58-128 mmHg; P<0.001), C_dyn was 4.4 mL/cmH₂O higher (95% CI: 1.9-6.9 mL/cmH₂O; P=0.001), and the driving pressure was 4.9 cmH₂O lower (95% CI: 3.8-6.1 cmH₂O; P<0.001) in the PEEP_EIT group than in the PEEP₅ group. PaO₂/FiO₂ was 107 mmHg higher (95% CI: 56-158 mmHg; P<0.001) in the PEEP_EIT group than in the PEEP₅ group during double-lung ventilation at the end of surgery.

Conclusions

PEEP values determined with EIT effectively improved oxygenation and lung mechanics during one lung ventilation in elderly patients undergoing thoracoscopic surgery.