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Proportional modes of ventilation assist the patient by adapting to his/her effort, which contrasts with all other modes. The two proportional modes are referred to as neurally adjusted ventilatory assist (NAVA) and proportional assist ventilation with load-adjustable gain factors (PAV+): they deliver inspiratory assist in proportion to the patient's effort, and hence directly respond to changes in ventilatory needs. Due to their working principles, NAVA and PAV+ have the ability to provide self-adjusted lung and diaphragm-protective ventilation. As these proportional modes differ from 'classical' modes such as pressure support ventilation (PSV), setting the inspiratory assist level is often puzzling for clinicians at the bedside as it is not based on usual parameters such as tidal volumes and PaCO.sub.2 targets. This paper provides an in-depth overview of the working principles of NAVA and PAV+ and the physiological differences with PSV. Understanding these differences is fundamental for applying any assisted mode at the bedside. We review different methods for setting inspiratory assist during NAVA and PAV+, and (future) indices for monitoring of patient effort. Last, differences with automated modes are mentioned., Author(s): Annemijn H. Jonkman [sup.1] [sup.2] [sup.3] , Michela Rauseo [sup.1] [sup.2] , Guillaume Carteaux [sup.4] [sup.5] [sup.6] , Irene Telias [sup.1] [sup.2] , Michael C. Sklar [sup.1] [sup.2] , [...]

BACKGROUND: Aerosol barrier enclosure systems have been designed to prevent airborne contamination, but their safety has been questioned. A vacuum tent was designed with active continuous suctioning to minimize risks of aerosol dispersion. We tested its efficacy, risk of rebreathing, and usability on a bench, in healthy volunteers, and in an ergonomic clinical assessment study. METHODS: First, a manikin with airway connected to a breathing simulator was placed inside the vacuum tent to generate active breathing, cough, and CO2 production; high-flow nasal cannula (HFNC) was applied in the manikin's nares. Negative pressure was applied in the vacuum tent's apex port using wall suction. Fluorescent microparticles were aerosolized in the vacuum tent for qualitative assessment. To quantify particles inside and around vacuum tent (aerosol retention), an airtight aerosol chamber with aerosolized latex microparticles was used. The vacuum tent was tested on healthy volunteers breathing with and without HFNC. Last, its usability was assessed in 5 subjects by 5 different anesthesiologists for delivery of full anesthesia, including intubation and extubation. RESULTS: The vacuum tent was adjusted until no leak was visualized using fluorescent particles. The efficacy in retaining microparticles was confirmed quantitatively. CO2 accumulation inside the vacuum tent showed an inverse correlation with the suction flow in all conditions (normal breathing and HFNC 30 or 60 L/min) in bench and healthy volunteers. Particle removal efficacy and safe breathing conditions (CO2, temperature) were reached when suctioning was at least 60 L/min or 20 L/min > HFNC flow. Five subjects were successfully intubated and anesthetized without ergonomic difficulties and with minimal interference with workflow and an excellent overall assessment by the anesthesiologists. CONCLUSIONS: The vacuum tent effectively minimized aerosol dispersion. Its continuous suction system set at a high suction flow was crucial to avoid the spread of aerosol particles and CO rebreathing. [ABSTRACT FROM AUTHOR]

Rationale: Defining lung recruitability is needed for safe positive end-expiratory pressure (PEEP) selection in mechanically ventilated patients. However, there is no simple bedside method including both assessment of recruitability and risks of overdistension as well as personalized PEEP titration. Objectives: To describe the range of recruitability using electrical impedance tomography (EIT), effects of PEEP on recruitability, respiratory mechanics and gas exchange, and a method to select optimal EIT-based PEEP. Methods: This is the analysis of patients with coronavirus disease (COVID-19) from an ongoing multicenter prospective physiological study including patients with moderate-severe acute respiratory distress syndrome of different causes. EIT, ventilator data, hemodynamics, and arterial blood gases were obtained during PEEP titration maneuvers. EIT-based optimal PEEP was defined as the crossing point of the overdistension and collapse curves during a decremental PEEP trial. Recruitability was defined as the amount of modifiable collapse when increasing PEEP from 6 to 24 cm H2O (ΔCollapse24–6). Patients were classified as low, medium, or high recruiters on the basis of tertiles of ΔCollapse24–6. Measurements and Main Results: In 108 patients with COVID-19, recruitability varied from 0.3% to 66.9% and was unrelated to acute respiratory distress syndrome severity. Median EIT-based PEEP differed between groups: 10 versus 13.5 versus 15.5 cm H2O for low versus medium versus high recruitability (P, 0.05). This approach assigned a different PEEP level from the highest compliance approach in 81% of patients. The protocol was well tolerated; in four patients, the PEEP level did not reach 24 cm H2O because of hemodynamic instability. Conclusions: Recruitability varies widely among patients with COVID-19. EIT allows personalizing PEEP setting as a compromise between recruitability and overdistension. [ABSTRACT FROM AUTHOR]

The article discusses an automated algorithm based on esophageal pressure (Peso) to generate and quantify muscular pressure (Pmus) for synchronous and dyssynchronous efforts in patients with acute hypoxemic respiratory failure (AHRF). Topics discussed include the magnitude and timing of synchronous and dyssynchronous efforts in patients with AHRF under different modes of ventilation and compare them with healthy subjects.

Introduction Extracorporeal carbon dioxide removal (ECCO.sub.2R) has been proposed for hypercapnic respiratory failure in chronic obstructive pulmonary disease (COPD) exacerbations, to avoid intubation or reduce length of invasive ventilation. Balance of risks, efficacy, and benefits of ECCO.sub.2R in patients with COPD is unclear. Methods We systematically searched MEDLINE and EMBASE to identify all publications reporting use of ECCO.sub.2R in COPD. We looked at physiological and clinical efficacy. A favorable outcome was defined as prevention of intubation or successful extubation. Major and minor complications were compiled. Results We identified 3123 citations. Ten studies (87 patients), primarily case series, met inclusion criteria. ECCO.sub.2R prevented intubation in 65/70 (93 %) patients and assisted in the successful extubation of 9/17 (53 %) mechanically ventilated subjects. One case-control study matching to noninvasively ventilated controls reported lower intubation rates and hospital mortality with ECCO.sub.2R that trended toward significance. Physiological data comparing pre- to post-ECCO.sub.2R changes suggest improvements for pH (0.07-0.15 higher), PaCO.sub.2 (25 mmHg lower), and respiratory rate (7 breaths/min lower), but not PaO.sub.2/FiO.sub.2. Studies reported 11 major (eight bleeds requiring blood transfusion of 2 units, and three line-related complications, including one death related to retroperitoneal bleeding) and 30 minor complications (13 bleeds, five related to anticoagulation, and nine clotting-related device malfunctions resulting in two emergent intubations). Conclusion The technique is still experimental and no randomized trial is available. Recognizing selection bias associated with case series, there still appears to be potential for benefit of ECCO.sub.2R in patients with COPD exacerbations. However, it is associated with frequent and potentially severe complications. Higher-quality studies are required to better elucidate this risk-benefit balance., Author(s): Michael C. Sklar [sup.1] [sup.2], Francois Beloncle [sup.2] [sup.3], Christina M. Katsios [sup.2] [sup.4], Laurent Brochard [sup.2] [sup.4], Jan O. Friedrich [sup.2] [sup.4] Author Affiliations: (1) grid.17063.33, Department of [...]

Optimisation of oxygenation strategies in patients with hypoxaemic respiratory failure is a top priority for acute care physicians, as hypoxaemic respiratory failure is one of the leading causes of admission. Various oxygenation methods range from non-invasive face masks to high flow nasal cannulae, which have advantages and disadvantages for this heterogeneous patient group. Focus has turned toward examining the benefits of non-invasive ventilation, as this was heavily researched in resource-limited settings during the COVID-19 pandemic. The oxygenation strategy should be determined on an individualised basis for patients, and with new evidence from the COVID-19 pandemic, providers may now consider placing further emphasis on non-invasive approaches. As non-invasive ventilation continues to be used in increasing frequency, new methods of monitoring patient response, including when to escalate ventilation strategy, will need to be validated. [ABSTRACT FROM AUTHOR]

Rationale: Patients with hematologic malignancies requiring mechanical ventilation have historically experienced poor outcomes.Objectives: We aimed to determine whether body composition characteristics derived from thoracic computed tomographic (CT) imaging were associated with time to liberation from mechanical ventilation.Methods: We evaluated mechanically ventilated patients with hematological malignancies admitted between 2014 and 2018. We included patients with thoracic CT imaging completed between 1 month before and 48 hours after intensive care unit (ICU) admission. We assessed the association of carinal skeletal muscle cross-sectional area (CSA), subcutaneous fat CSA, and fat index (fat/skeletal muscle ratio) with time to liberation from mechanical ventilation within 28 days. We accounted for the competing event of death within 28 days of mechanical ventilation.Results: One hundred fifty-six patients were included; the mean age was 57 years (standard deviation 14) and 39% were female. Thirty-seven percent had received a hematopoietic stem cell transplant, and the median ratio of arterial oxygen tension/pressure to fraction of inspired oxygen was 134 mm Hg (interquartile range [IQR], 92-205). Median skeletal muscle CSA was 68 cm2 (IQR, 54-88) and subcutaneous fat CSA was 38 cm2 (IQR, 27-52). Forty-two percent of patients were liberated from mechanical ventilation within 28 days and 56% died in the ICU. Subcutaneous fat CSA (subdistribution hazard ratio [sHR], 0.81; 95% confidence interval [95% CI], -0.68 to 0.97) and fat index (sHR, 0.81; 95% CI, -0.68 to 0.97) were significantly associated with longer time to liberation from mechanical ventilation. Skeletal muscle CSA was not associated with time to liberation from ventilation (sHR, 1.08; 95% CI, -0.94 to 1.23).Conclusions: Body composition measurements based on thoracic CT scans were associated with time to liberation from ventilation. These could represent novel surrogate markers of physical frailty in patients with hematologic malignancies receiving mechanical ventilation. [ABSTRACT FROM AUTHOR]

Objective: To understand changes in frailty and quality of life (QOL) in frail versus non‐frail patients undergoing surgery for head and neck cancer (HNC). Methods: Prospective cohort study of patients (median age 67 (50, 88)) with HNC undergoing surgery from December 2011 to April 2014. Fried's Frailty Index, Vulnerable Elders Survey (VES‐13), and comprehensive QOL assessments (EORTC QLQ‐C30 and HN35) were completed at baseline and 3, 6, and 12‐month post‐operative visits. Change in frailty and QOL over time was compared between frailty groups (non‐frail (score 0), pre‐frail (score 1–2), and frail (score 3–5)) using a mixed effects model. Predictors of long‐term elevated frailty (12 months > baseline) were analyzed using logistic regression. Results: The study had 108 patients classified as non‐frail (47%), 104 pre‐frail (mean (SD) 1.3 (0.4), 45%), and 17 frail (3.4 (0.6); 7%). Frailty score decreased significantly for frail patients 3 months post‐operatively (2.1 (1.0); P =.002) and remained significantly lower than baseline at 6 and 12 months (2.1 (1.4); P =.0008 and 2.2 (1.5); P =.005, respectively) while frailty score increased for non‐frail patients at 3 months (1.1 (1.0); P <.001) and then decreased. Forty‐eight patients (21%) had long‐term elevated frailty, with baseline frailty and marital status identified as predictors on univariate analysis. The frail population had significantly worse QOL scores at baseline, which persisted 12 months post‐operatively. Conclusions: Frail patients demonstrate a decrease in frailty score following surgical treatment of HNC. Frail patients have significantly worse QOL scores on longitudinal assessment and would benefit from supportive services throughout their care. Level of Evidence: 3 Laryngoscope, 131:E2232–E2242, 2021 [ABSTRACT FROM AUTHOR]

BACKGROUND: Diaphragmatic respiratory effort during mechanical ventilation is an important determinant of patient outcome, but direct measurement of diaphragmatic contractility requires specialized instrumentation and technical expertise. We sought to determine whether routinely collected clinical variables can predict diaphragmatic contractility and stratify the risk of diaphragm atrophy. METHODS: We conducted a secondary analysis of a prospective cohort study on diaphragm ultrasound in mechanically ventilated subjects. Clinical variables, such as breathing frequency, ventilator settings, and blood gases, were recorded longitudinally. Machine learning techniques were used to identify variables predicting diaphragm contractility and stratifying the risk of diaphragm atrophy (> 10% decrease in thickness from baseline). Performance of the variables was evaluated in mixed-effects logistic regression and random-effects tree models using the area under the receiver operating characteristic curve. RESULTS: Measurements were available for 761 study days in 191 subjects, of whom 73 (38%) developed diaphragm atrophy. No routinely collected clinical variable, alone or in combination, could accurately predict either diaphragm contractility or the development of diaphragm atrophy (model area under the receiver operating characteristic curve 0.63--0.75). The risk of diaphragm atrophy was not significantly different according to the pres- ence or absence of patient-triggered breaths (38.3% vs 38.6%; odds ratio 1.01, 95% CI 0.05--2.03). Diaphragm thickening fraction < 15% during either of the first 2 d of the study was associated with a higher risk of atrophy (44.6% vs 26.1%; odds ratio 2.28, 95% CI 1.05--4.95). CONCLUSIONS: Diaphragmatic contractility and the risk of diaphragm atrophy could not be reliably determined from routinely collected clinical variables and ventilator settings. A single measurement of dia- phragm thickening fraction measured within 48 h of initiating mechanical ventilation can be used to stratify the risk of diaphragm atrophy during mechanical ventilation. [ABSTRACT FROM AUTHOR]

Background: Acute increases in muscle sonographic echodensity reflect muscle injury. Diaphragm echodensity has not been measured in mechanically ventilated patients. We undertook to develop a technique to characterize changes in diaphragm echodensity during mechanical ventilation and to assess whether these changes are correlated with prolonged mechanical ventilation.Methods: Diaphragm ultrasound images were prospectively collected in mechanically ventilated patients and in 10 young healthy subjects. Echodensity was quantified based on the right-skewed distribution of grayscale values (50th percentile, ED50; 85th percentile, ED85). Intra- and inter-analyzer measurement reproducibility was determined. Outcomes recorded included duration of ventilation and ICU complications (including reintubation, tracheostomy, prolonged ventilation, or death).Results: Echodensity measurements were obtained serially in 34 patients comprising a total of 104 images. Baseline (admission) diaphragm ED85 was increased in mechanically ventilated patients compared to younger healthy subjects (median 56, interquartile range (IQR) 42-84, vs. 39, IQR 36-52, p = 0.04). Patients with an initial increase in median echodensity over time (≥ + 10 in ED50 from baseline) had fewer ventilator-free days to day 60 (n = 13, median 46, IQR 0-52) compared to patients without this increase (n = 21, median 53 days, IQR 49-56, unadjusted p = 0.03). Both decreases and increases in diaphragm thickness during mechanical ventilation were associated with increases in ED50 over time (adjusted p = 0.03, conditional R2 = 0.80) and the association between increase in ED50 and outcomes persisted after adjusting for changes in diaphragm thickness.Conclusions: Many patients exhibit increased diaphragm echodensity at the outset of mechanical ventilation. Increases in diaphragm echodensity during the early course of mechanical ventilation are associated with prolonged mechanical ventilation. Both decreases and increases in diaphragm thickness during mechanical ventilation are associated with increased echodensity. [ABSTRACT FROM AUTHOR]

Background: Being able to predict negative postoperative outcomes is important for helping select patients for treatment as well for informed decision‐making by patients. Frailty measures are often time and resource intensive to use as screening measures, whereas the Braden scale, a commonly used measure to assess patients at risk of developing pressure ulcers after surgery, may be a potential tool to predict postoperative complication rates and longer length of stay (LOS) in patients undergoing major head and neck cancer surgery. Methods: A retrospective analysis of Braden scale scores was performed on a prospectively collected cohort of patients undergoing major head and neck surgery recruited between December 2011 and April 2014. The association of Braden scale score with the primary outcomes of complications and LOS was analyzed using logistic regression and linear regression models on univariate analysis (UVA), respectively. Multivariate analysis (MVA) was performed based on a backward stepwise selection algorithm. Results: There were 232 patients with a mean (SD) Braden scale score of 14.9 (2.8) with a range from 9 to 23. The Braden scale (β = −.07 per point; 95% CI −0.09, −0.04, P <.001) was an independent predictor of increased LOS on UVA, but not on MVA when adjusted for other variables. For overall complications, as well as type of complication, the Braden scale score was not a significant predictor of complications on either UVA or MVA. Conclusion: In the sample population, the Braden scale did not demonstrate an ability to predict negative outcomes in head and neck surgery patients. Level of Evidence: Level 2b individual cohort study. Being able to predict negative postoperative outcomes is important for helping select patients for treatment as well for informed decision‐making by patients. The Braden Scale, a commonly used measure to assess patients at risk of developing pressure ulcers after surgery, may be a potential tool to predict postoperative complication rates and longer length of stay in patients undergoing major head and neck cancer surgery. In the sample population the Braden scale did not demonstrate an ability to predict negative outcomes in head and neck surgery patients [ABSTRACT FROM AUTHOR]

The article looks at a study single-center observational study regarding lung recruitability in COVID-19–associated Acute Respiratory Distress Syndrome (ARDS). It mentions clinical question with regard to personalizing the management of these patients is whether the lungs are recruitable with high positive end-expiratory pressure (PEEP) for each individual patient. It also mentions increase in end expiratory lung volume induced by PEEP is distributed between the recruited lung.

Objectives: To evaluate whether frailty and functional measures are predictors of perioperative complications and length of hospital stay (LOS) in patients undergoing head and neck cancer surgery.Study Design: Prospective study.Methods: Patients 50 years and older undergoing major head and neck cancer surgery between 2011 and 2015 preoperatively completed Fried's Frailty Index, Barthel Index, Lawton-Brody questionnaire and Vulnerable Elders Survey-13. Primary outcome measures were postoperative complications and LOS, which were analyzed using multivariable logistic and linear regression models.Results: There were 274 patients recruited (105 aged 50-64 and 169 aged 65 and older). Of these, 119, 132, and 23 were defined as non-frail, pre-frail, and frail, respectively. Frailty score and functional measures were not predictors of overall complications. In multivariable models, frailty score (odds ratio [OR] = 1.36; 95% confidence interval [CI], 1.04-1.78, P = .025) was a predictor of medical complications and Clavien-Dindo Grade III and higher complications independent of age and comorbidity. Higher frailty score (β = 1.07; 95% CI, 1.02-1.12, P = .0025) and less independence on the Lawton Brody (β = -0.08; 95% CI, -0.11 to -0.05, P < .001) and Barthel Index (β = -0.12; 95% CI, -0.19 to -0.06, P < .001) were predictors of increased LOS.Conclusions: Frailty was a predictor of type and severity of complications. Both frailty and measures of independence in activities of daily living were independent predictors of LOS. Frailty and functional assessment can help surgeons identify patients at risk of adverse postoperative outcomes and thus aid in counselling patients as well as identifying patients that may benefit from comprehensive geriatric assessment and targeted interventions.Level Of Evidence: Prognosis study 2b Laryngoscope, 130:E340-E345, 2020. [ABSTRACT FROM AUTHOR]

Rationale: Response to positive end-expiratory pressure (PEEP) in acute respiratory distress syndrome depends on recruitability. We propose a bedside approach to estimate recruitability accounting for the presence of complete airway closure.Objectives: To validate a single-breath method for measuring recruited volume and test whether it differentiates patients with different responses to PEEP.Methods: Patients with acute respiratory distress syndrome were ventilated at 15 and 5 cm H2O of PEEP. Multiple pressure-volume curves were compared with a single-breath technique. Abruptly releasing PEEP (from 15 to 5 cm H2O) increases expired volume: the difference between this volume and the volume predicted by compliance at low PEEP (or above airway opening pressure) estimated the recruited volume by PEEP. This recruited volume divided by the effective pressure change gave the compliance of the recruited lung; the ratio of this compliance to the compliance at low PEEP gave the recruitment-to-inflation ratio. Response to PEEP was compared between high and low recruiters based on this ratio.Measurements and Main Results: Forty-five patients were enrolled. Four patients had airway closure higher than high PEEP, and thus recruitment could not be assessed. In others, recruited volume measured by the experimental and the reference methods were strongly correlated (R2 = 0.798; P < 0.0001) with small bias (-21 ml). The recruitment-to-inflation ratio (median, 0.5; range, 0-2.0) correlated with both oxygenation at low PEEP and the oxygenation response; at PEEP 15, high recruiters had better oxygenation (P = 0.004), whereas low recruiters experienced lower systolic arterial pressure (P = 0.008).Conclusions: A single-breath method quantifies recruited volume. The recruitment-to-inflation ratio might help to characterize lung recruitability at the bedside.Clinical trial registered with www.clinicaltrials.gov (NCT02457741). [ABSTRACT FROM AUTHOR]

The article presents the case study of 44-year-old man with venovenous extracorporeal membrane oxygenation (ECMO) for coronavirus disease (COVID-19) associated acute respiratory distress syndrome (ARDS). Topics include mechanical ventilation settings were changed to pressure control with inspiratory pressure of 10 cm H2O above positive end-expiratory pressure (PEEP); and assessment of respiratory mechanics can be erroneous when AOP is not measured.

Mechanical ventilation practices in patients with acute respiratory distress syndrome (ARDS) have progressed with a growing understanding of the disease pathophysiology. Paramount to the care of affected patients is the delivery of lung-protective mechanical ventilation which prioritizes tidal volume and plateau pressure limitation. Lung protection can probably be further enhanced by scaling target tidal volumes to the specific respiratory mechanics of individual patients. The best procedure for selecting optimal positive end-expiratory pressure (PEEP) in ARDS remains uncertain; several relevant issues must be considered when selecting PEEP, particularly lung recruitability. Noninvasive ventilation must be used with caution in ARDS as excessively high respiratory drive can further exacerbate lung injury; newer modes of delivery offer promising approaches in hypoxemic respiratory failure. Airway pressure release ventilation offers an alternative approach to maximize lung recruitment and oxygenation, but clinical trials have not demonstrated a survival benefit of this mode over conventional ventilation strategies. Rescue therapy with high-frequency oscillatory ventilation is an important option in refractory hypoxemia. Despite a disappointing lack of benefit (and possible harm) in patients with moderate or severe ARDS, possibly due to lung hyperdistention and right ventricular dysfunction, high-frequency oscillation may improve outcome in patients with very severe hypoxemia. [ABSTRACT FROM AUTHOR]

BACKGROUND: High-flow nasal-cannula (HFNC) may be an oxygen modality useful for preventing invasive mechanical ventilation and mortality; however, its role in acute hypoxemic respiratory failure is not clearly defined. We sought to evaluate the impact of HFNC on mortality across immunocompromised subjects compared to alternative noninvasive oxygen therapies, namely conventional oxygen therapy and noninvasive ventilation (NIV). METHODS: We systematically searched the major databases to identify randomized, controlled trials (RCTs) or observational studies (until May 2018). We included studies reporting the use of HFNC in immunocompromised subjects and evaluated its impact on mortality and invasive mechanical ventilation. RESULTS: Upon review of 6,506 titles, 13 studies (1,956 subjects) fulfilled our inclusion criteria (4 RCTs, 9 observational studies). The predominant cause of immunocompromised status was cancer. Bacterial pneumonia was the most common cause of acute hypoxemic respiratory failure with a median PaO2/FIO2 of 145 mm Hg (interquartile range 115-175). HFNC was used as the first oxygen strategy in 474 subjects compared to NIV (242 subjects) and conventional O2 therapy (703 subjects). There was a 46% rate of invasive mechanical ventilation and 36% mortality. Mortality at the longest available follow-up was lower with HFNC compared to the oxygen therapy controls (NIV or conventional O2 therapy) in 7 studies (1,429 subjects; relative risk 0.72, 95% CI 0.56-0.93, P = .01). There was a lower rate of invasive mechanical ventilation with HFNC compared to the oxygen therapy controls across 8 studies (1,529 subjects, relative risk 0.81, 95% CI 0.67-0.96, P = .02). These results were robust across a series of sensitivity analyses. CONCLUSIONS: There exists a need to develop a greater evidence base evaluating the utility of HFNC in immunocompromised subjects. In our exploratory analysis, HFNC was found to decrease mortality and use of invasive mechanical ventilation compared to alternative noninvasive oxygen controls. These results are meant to be exploratory. Higher-quality studies evaluating a more homogeneous population are needed to further elucidate its benefit. [ABSTRACT FROM AUTHOR]

Intubation practices and adverse peri-intubation events in critically ill patients from 29 countries. Effect of fluid bolus administration on cardiovascular collapse among critically ill patients undergoing tracheal intubation: a randomized clinical trial. [Extracted from the article]

Rationale: Spontaneous breathing trials (SBTs) are designed to simulate conditions after extubation, and it is essential to understand the physiologic impact of different methods.Objectives: We conducted a systematic review and pooled measures reflecting patient respiratory effort among studies comparing SBT methods in a meta-analysis.Methods: We searched Medline, Excerpta Medica Database, and Web of Science from inception to January 2016 to identify randomized and nonrandomized clinical trials reporting physiologic measurements of respiratory effort (pressure-time product) or work of breathing during at least two SBT techniques. Secondary outcomes included the rapid shallow breathing index (RSBI), and effort measured before and after extubation. The quality of physiologic measurement and research design was appraised for each study. Outcomes were analyzed using ratio of means.Measurements and Main Results: Among 4,138 citations, 16 studies (n = 239) were included. Compared with T-piece, pressure support ventilation significantly reduced work by 30% (ratio of means [RoM], 0.70; 95% confidence interval [CI], 0.57-0.86), effort by 30% (RoM, 0.70; 95% CI, 0.60-0.82), and RSBI by 20% (RoM, 0.80; 95% CI, 0.75-0.86). Continuous positive airway pressure had significantly lower pressure-time product by 18% (RoM, 0.82; 95% CI, 0.68-0.999) compared with T-piece, and reduced RSBI by 16% (RoM, 0.84; 95% CI, 0.74-0.95). Studies comparing SBTs with the postextubation period demonstrated that pressure support induced significantly lower effort and RSBI; T-piece reduced effort, but not the work, compared with postextubation. Work, effort, and RSBI measured while intubated on the ventilator with continuous positive airway pressure of 0 cm H2O were no different than extubation.Conclusions: Pressure support reduces respiratory effort compared with T-piece. Continuous positive airway pressure of 0 cm H2O and T-piece more accurately reflect the physiologic conditions after extubation. [ABSTRACT FROM AUTHOR]

Background: The optimal anticoagulation strategy for venovenous extracorporeal membrane oxygenation (VV-ECMO) is not known.Objectives: To evaluate the safety of anticoagulation strategies and monitoring during VV-ECMO for respiratory failure.Data Sources: We conducted a systematic review to evaluate the association between anticoagulation strategies during VV-ECMO and prespecified outcomes, including major bleeding episodes, thrombotic events, and in-hospital mortality. We included articles published between 1977 and January 30, 2015. Study quality was assessed using the Newcastle-Ottawa scoring system. A separate meta-analysis was not planned.Data Extraction: Data were independently extracted by two authors and collected on a standardized report form.Synthesis: A total of 18 studies (n = 646) were included; 17 studies enrolled patients with acute respiratory distress syndrome. Across all studies, the duration of VV-ECMO support ranged from 4 to 20 days. Patients received an average of 2.3 (±3.9) units of transfused red blood cells per day. The bleeding rate across all studies was 16%, and the rate of thrombosis was 53%. Among seven studies (199 patients) targeting a specified activated partial thromboplastin time (aPTT), there were 37 (19%) major bleeding episodes and 53 (27%) major thromboses. Among five studies (43 patients) with aPTT targets of 60 seconds or greater, there were 24 (56%) bleeding episodes and 3 (7%) clotting events. Three studies (156 patients) with an aPTT target under 60 seconds reported 13 (8%) and 50 (32%) significant bleeding and thrombotic events, respectively. The most commonly reported thrombotic events were circuit-related clotting and deep-vein thrombosis. Mortality during VV-ECMO varied across the studies, ranging from 0 to at least 50% at heterogeneous time points. The total number of deaths for all studies combined was 186 (29%).Conclusions: The role and optimal therapeutic targets for anticoagulation during VV-ECMO are unclear. Previously published studies are limited by retrospective, observational design, small cohorts, and patient heterogeneity. The clinical significance of reported thrombotic complications is largely unknown. This systematic review underscores the need for randomized controlled trials of anticoagulation strategies for patients undergoing VV-ECMO for respiratory failure. [ABSTRACT FROM AUTHOR]