Etiology, incidence, and outcomes of patient-ventilator asynchrony in critically-ill patients undergoing invasive mechanical ventilation.

Patient-ventilator asynchrony (PVA) is commonly encountered during mechanical ventilation of critically ill patients. Estimates of PVA incidence vary widely. Type, risk factors, and consequences of PVA remain unclear. We aimed to measure the incidence and identify types of PVA, characterize risk factors for development, and explore the relationship between PVA and outcome among critically ill, mechanically ventilated adult patients admitted to medical, surgical, and medical-surgical intensive care units in a large academic institution staffed with varying provider training background. A single center, retrospective cohort study of all adult critically ill patients undergoing invasive mechanical ventilation for ≥ 12 h. A total of 676 patients who underwent 696 episodes of mechanical ventilation were included. Overall PVA occurred in 170 (24%) episodes. Double triggering 92(13%) was most common, followed by flow starvation 73(10%). A history of smoking, and pneumonia, sepsis, or ARDS were risk factors for overall PVA and double triggering (all P < 0.05). Compared with volume targeted ventilation, pressure targeted ventilation decreased the occurrence of events (all P < 0.01). During volume controlled synchronized intermittent mandatory ventilation and pressure targeted ventilation, ventilator settings were associated with the incidence of overall PVA. The number of overall PVA, as well as double triggering and flow starvation specifically, were associated with worse outcomes and fewer hospital-free days (all P < 0.01). Double triggering and flow starvation are the most common PVA among critically ill, mechanically ventilated patients. Overall incidence as well as double triggering and flow starvation PVA specifically, portend worse outcome.

The Impact of a Standardized Refractory Hypoxemia Protocol on Outcome of Subjects Receiving Venovenous Extracorporeal Membrane Oxygenation.

BACKGROUND: Current mechanical ventilation practice and the use of treatment adjuncts in patients requiring extracorporeal membrane oxygenation (ECMO) for refractory hypoxemia (RH) vary widely and their impact on outcomes remains unclear. In 2015, we implemented a standardized approach to protocolized ventilator settings and guide the escalation of adjunct therapies in patients with RH. This study aimed to investigate ICU mortality, its associated risk factors, and mechanical ventilation practice before and after the implementation of a standardized RH guideline in patients requiring venovenous ECMO (VV-ECMO). METHODS: This was a single-center, retrospective cohort study of patients undergoing VV-ECMO due to RH respiratory failure between January 2008 and March 2015 (before RH protocol implementation) and between April 2015 and October 2019 (after RH protocol implementation). RESULTS: A total of 103 subjects receiving VV-ECMO for RH were analyzed. After implementation of the RH protocol, more subjects received prone positioning (6.7% vs 23.3%, P = .02), and fewer received high-frequency oscillatory ventilation than before launching the RH protocol (0% vs 13.3%, P = .01). Plateau pressure was also lower before initiation of ECMO (P = .04) and at day 1 during ECMO (P = .045). Driving pressure was consistently lower at days 1, 2, and 3 after ECMO initiation: median 13.0 (interquartile range [IQR] 10.6-18.0) vs 16.0 (IQR 14.0-20.0) cm H2O at day 1 (P = .003); 13.0 (IQR 11.0-15.9) vs 15.5 (IQR 12.0-20.0) cm H2O at day 2 (P = .03); and 12.0 (IQR 10.0-14.5) vs 15.0 (IQR 12.0-19.0) cm H2O at day 3 (P = .005). CONCLUSIONS: The implementation of a standardized RH guideline improved compliance with a lung-protective ventilation strategy and utilization of the prone position and was associated with lower driving pressure during the first 3 days after ECMO initiation in subjects with refractory hypoxemia.

Electronic Medical Record-Based Pager Notification Reduces Excess Oxygen Exposure in Mechanically Ventilated Subjects.

BACKGROUND: Liberal oxygenation during mechanical ventilation is harmful in critically ill patients and in certain subsets of patients, including those with stroke, acute myocardial infarction, and cardiac arrest. Surveillance through electronic medical records improves safety of mechanical ventilation in the ICU. To date, this practice has not been used for oxygen titration ([Formula: see text]) in adults. We hypothesize that a surveillance system based on the electronic medical record to alert respiratory therapists to titrate [Formula: see text] is feasible, safe, and efficacious. METHODS: In this pilot study, mechanically ventilated subjects were randomized to respiratory therapist-driven [Formula: see text] titration after an electronic alert versus standard of care (ie, titration based on physician order). An automated surveillance system utilizing a hyperoxemia-detection algorithm generated an electronic alert to a respiratory therapist's pager. Hyperoxemia was defined as [Formula: see text] > 0.5 and [Formula: see text] > 95% for > 30 min. No other aspects of treatment were changed. We assessed feasibility, safety, and preliminary efficacy. Primary outcome was duration of hyperoxemia during mechanical ventilation. An unsafe outcome was identified as hypoxemia ([Formula: see text] < 88%) within 1 h after titration per alert. Feasibility was assessed by a survey of respiratory therapists. RESULTS: Of 226 randomized subjects, 31 were excluded (eg, programming errors of the electronic alerts, no consent, physician discretion). We included 195 subjects, of whom 86 were in the intervention arm. Alert accuracy was 78%, and respiratory therapists responded to 64% of the alerts. During mechanical ventilation, exposure to hyperoxemia significantly decreased in the intervention group (median 13.5 h [interquartile range 6.2-29.4] vs 18.8 h [interquartile range 9.6-37.4]). No episodes of significant hypoxemia were registered. Most respiratory therapists agreed that the alert was helpful in reducing excessive oxygen exposure. CONCLUSIONS: Use of an electronic surveillance system to titrate [Formula: see text] was safe and feasible and showed preliminary efficacy in reducing hyperoxemia. Our study serves to justify larger randomized controlled trials for [Formula: see text] titration.

Updated guidance on the management of COVID-19: from an American Thoracic Society/European Respiratory Society coordinated International Task Force (29 July 2020).

BACKGROUND: Coronavirus disease 2019 (COVID-19) is a disease caused by severe acute respiratory syndrome-coronavirus-2. Consensus suggestions can standardise care, thereby improving outcomes and facilitating future research. METHODS: An International Task Force was composed and agreement regarding courses of action was measured using the Convergence of Opinion on Recommendations and Evidence (CORE) process. 70% agreement was necessary to make a consensus suggestion. RESULTS: The Task Force made consensus suggestions to treat patients with acute COVID-19 pneumonia with remdesivir and dexamethasone but suggested against hydroxychloroquine except in the context of a clinical trial; these are revisions of prior suggestions resulting from the interim publication of several randomised trials. It also suggested that COVID-19 patients with a venous thromboembolic event be treated with therapeutic anticoagulant therapy for 3 months. The Task Force was unable to reach sufficient agreement to yield consensus suggestions for the post-hospital care of COVID-19 survivors. The Task Force fell one vote shy of suggesting routine screening for depression, anxiety and post-traumatic stress disorder. CONCLUSIONS: The Task Force addressed questions related to pharmacotherapy in patients with COVID-19 and the post-hospital care of survivors, yielding several consensus suggestions. Management options for which there is insufficient agreement to formulate a suggestion represent research priorities.

Association of Home Noninvasive Positive Pressure Ventilation With Clinical Outcomes in Chronic Obstructive Pulmonary Disease: A Systematic Review and Meta-analysis.

Importance: The association of home noninvasive positive pressure ventilation (NIPPV) with outcomes in chronic obstructive pulmonary disease (COPD) and hypercapnia is uncertain. Objective: To evaluate the association of home NIPPV via bilevel positive airway pressure (BPAP) devices and noninvasive home mechanical ventilator (HMV) devices with clinical outcomes and adverse events in patients with COPD and hypercapnia. Data Sources: Search of MEDLINE, EMBASE, SCOPUS, Cochrane Central Registrar of Controlled Trials, Cochrane Database of Systematic Reviews, National Guideline Clearinghouse, and Scopus for English-language articles published from January 1, 1995, to November 6, 2019. Study Selection: Randomized clinical trials (RCTs) and comparative observational studies that enrolled adults with COPD with hypercapnia who used home NIPPV for more than 1 month were included. Data Extraction and Synthesis: Data extraction was completed by independent pairs of reviewers. Risk of bias was evaluated using the Cochrane Collaboration risk of bias tool for RCTs and select items from the Newcastle-Ottawa Scale for nonrandomized studies. Main Outcomes and Measures: Primary outcomes were mortality, all-cause hospital admissions, need for intubation, and quality of life at the longest follow-up. Results: A total of 21 RCTs and 12 observational studies evaluating 51 085 patients (mean [SD] age, 65.7 [2.1] years; 43% women) were included, among whom there were 434 deaths and 27 patients who underwent intubation. BPAP compared with no device was significantly associated with lower risk of mortality (22.31% vs 28.57%; risk difference [RD], -5.53% [95% CI, -10.29% to -0.76%]; odds ratio [OR], 0.66 [95% CI, 0.51-0.87]; P = .003; 13 studies; 1423 patients; strength of evidence [SOE], moderate), fewer patients with all-cause hospital admissions (39.74% vs 75.00%; RD, -35.26% [95% CI, -49.39% to -21.12%]; OR, 0.22 [95% CI, 0.11-0.43]; P < .001; 1 study; 166 patients; SOE, low), and lower need for intubation (5.34% vs 14.71%; RD, -8.02% [95% CI, -14.77% to -1.28%]; OR, 0.34 [95% CI, 0.14-0.83]; P = .02; 3 studies; 267 patients; SOE, moderate). There was no significant difference in the total number of all-cause hospital admissions (rate ratio, 0.91 [95% CI, 0.71-1.17]; P = .47; 5 studies; 326 patients; SOE, low) or quality of life (standardized mean difference, 0.16 [95% CI, -0.06 to 0.39]; P = .15; 9 studies; 833 patients; SOE, insufficient). Noninvasive HMV use compared with no device was significantly associated with fewer all-cause hospital admissions (rate ratio, 0.50 [95% CI, 0.35-0.71]; P < .001; 1 study; 93 patients; SOE, low), but not mortality (21.84% vs 34.09%; RD, -11.99% [95% CI, -24.77% to 0.79%]; OR, 0.56 [95% CI, 0.29-1.08]; P = .49; 2 studies; 175 patients; SOE, insufficient). There was no statistically significant difference in the total number of adverse events in patients using NIPPV compared with no device (0.18 vs 0.17 per patient; P = .84; 6 studies; 414 patients). Conclusions and Relevance: In this meta-analysis of patients with COPD and hypercapnia, home BPAP, compared with no device, was associated with lower risk of mortality, all-cause hospital admission, and intubation, but no significant difference in quality of life. Noninvasive HMV, compared with no device, was significantly associated with lower risk of hospital admission, but there was no significant difference in mortality risk. However, the evidence was low to moderate in quality, the evidence on quality of life was insufficient, and the analyses for some outcomes were based on small numbers of studies.

The Clinical Effect of an Early, Protocolized Approach to Mechanical Ventilation for Severe and Refractory Hypoxemia.

BACKGROUND: ARDS remains a source of significant morbidity and mortality in the critically ill patient. The mainstay of therapy entails invasive mechanical ventilation utilizing a lung-protective strategy designed to limit lung injury associated with excessive stress and strain while the underlying etiology of respiratory failure is identified and treated. Less is understood about what to do once conventional ventilation parameters have been optimized but the patient's respiratory status remains unchanged or worsens. In 2015, a protocolized, stepwise approach to mechanical ventilation with partially automated and clearly defined thresholds for management changes was implemented at our institution. We hypothesized that, by identifying appropriate patients earlier, time-to-escalation and rescue therapy implementation would be shortened. METHODS: Subjects with severe ARDS, treated with prone positioning based on our institution's protocolized approach from December 2013 to August 2016 were included. Their baseline characteristics, severity of illness scores, and mechanical ventilation parameters were collected and analyzed. RESULTS: Baseline characteristics, tidal volumes, PaO2 /FIO2 , duration of ventilation after proning, and mortality were similar in both groups. Median (interquartile range [IQR]) PEEP at the time of proning was higher after the protocol implementation (12.5 cm H2O [IQR 6.5-19.4] vs 18 cm H2O [IQR 10-22], P = .386), and mean (IQR) respiratory system driving pressure was lower (16 cm H2O [IQR 13-36.2] vs 12 cm H2O [IQR 9-19.6], P = .029). Median (IQR) time from refractory hypoxemia identification to proning was shorter after protocol implementation (42.2 h [IQR 6.83-347.2] vs 16.3 h [IQR 1-99.7], I = .02), and PaO2 /FIO2 at 1 h after proning was higher. ICU and hospital LOS were shorter after the protocol implementation. CONCLUSIONS: Following the implementation of an early, evidence-based, protocolized approach to optimizing mechanical ventilation, subjects with true refractory hypoxemia were identified earlier and time to proning was significantly shorter. Despite improvement in the evaluation and management of refractory hypoxemia as well as time to initiation of prone positioning, mortality was unchanged and there was variation in the duration of the position.

Effectiveness of hands-on tutoring and guided self-directed learning versus self-directed learning alone to educate critical care fellows on mechanical ventilation - a pilot project.

BACKGROUND: Physicians require extensive training to achieve proficiency in mechanical ventilator (MV) management of the critically ill patients. Guided self-directed learning (GSDL) is usually the method used to learn. However, it is unclear if this is the most proficient approach to teaching mechanical ventilation to critical care fellows. We, therefore, investigated whether critical care fellows achieve higher scores on standardized testing and report higher satisfaction after participating in a hands-on tutorial combined with GSDL compared to self-directed learning alone. METHODS: First-year Pulmonary and Critical Care Medicine (PCCM) fellows (n=6) and Critical Care Internal Medicine (CCIM) (n=8) fellows participated. Satisfaction was assessed using the Likert scale. MV knowledge assessment was performed by administering a standardized 25-question multiple choice pre- and posttest. For 2 weeks the CCIM fellows were exposed to GSDL, while the PCCM fellows received hands-on tutoring combined with GSDL. RESULTS: Ninety-three percentage (6 PCCM and 7 CCIM fellows, total of 13 fellows) completed all evaluations and were included in the final analysis. CCIM and PCCM fellows scored similarly in the pretest (64% vs. 52%, p=0.13). Following interventions, the posttest scores increased in both groups. However, no significant difference was observed based on the interventions (74% vs. 77%, p=0.39). The absolute improvement with the hands-on-tutoring and GSDL group was higher than GSDL alone (25% vs. 10%, p=0.07). Improved satisfaction scores were noted with hands-on tutoring. CONCLUSIONS: Hands-on tutoring combined with GSDL and GSDL alone were both associated with an improvement in posttest scores. Absolute improvement in test and satisfaction scores both trended higher in the hands-on tutorial group combined with GSDL group.

Is Automated Weaning Superior to Manual Spontaneous Breathing Trials?

Weaning from mechanical ventilation involves the reduction or withdrawal of ventilatory support in proportion to the patient's ability to sustain spontaneous ventilation. Protocolized weaning has been shown to reduce weaning duration; however, its weakness lies in the reliance on human intervention. Automated weaning is theoretically superior to manual weaning because of its ability to rapidly recognize deviations from desired behavior and enforce compliance with a standardized weaning strategy unencumbered by external influences. Whether currently available methods for automated weaning fulfill that potential to achieve superiority depends on patient type, care environment, and cause of ventilator dependence.

Should a Portable Ventilator Be Used in All In-Hospital Transports?

Movement of the mechanically ventilated patient may be for a routine procedure or medical emergency. The risks of transport seem manageable, but the memory of a respiratory-related catastrophe still gives many practitioners pause. The risk/benefit ratio of transport must be assessed before movement. During transport of the ventilated patients, should we always use a transport ventilator? What is the risk of using manual ventilation? How are PEEP and FIO2 altered? Is there an impact on the ability to trigger during manual ventilation? Is hyperventilation and hypoventilation a common problem? Does hyperventilation or hypoventilation result in complications? Are portable ventilators worth the cost? What about the function of portable ventilators? Can these devices faithfully reproduce ICU ventilator function? The following pro and con discussion will attempt to address many of these issues by reviewing the current evidence on transport ventilation.

High-flow nasal cannula therapy in do-not-intubate patients with hypoxemic respiratory distress.

BACKGROUND: Patients with do-not-intubate (DNI) status and respiratory failure are commonly treated with noninvasive ventilation (NIV). High-flow nasal cannula (HFNC) therapy supplies a high flow of heated and humidified oxygen that may provide an effective alternative to NIV. We assessed the efficacy of HFNC in DNI patients with hypoxemic respiratory distress. METHODS: We identified 50 DNI patients with hypoxemic respiratory distress who were admitted to a medical ICU and who received HFNC. We excluded patients with PaCO2 > 65 mm Hg and pH < 7.28. The primary end point was the need for escalation to NIV, as determined by the primary service. Mean changes in oxygen saturation and breathing frequency before and after HFNC were compared. RESULTS: The subjects included 25 men and 25 women, mean age 73 years (range 27-96 y). Diagnoses (allowing multiple conditions) included pulmonary fibrosis (15), pneumonia (15), COPD (12), cancer (7), hematologic malignancy (7), and congestive heart failure (3). Hospital mortality was 60% (30/50). HFNC was initiated at a mean FIO2 of 0.67 (range 0.30-1.0) and flow of 42.6 L/min (range 30-60 L/min). Mean O2 saturations went from 89.1% to 94.7% (P < .001), and breathing frequency went from 30.6 breaths/min to 24.7 breaths/min (P < .001). Nine of the 50 subjects (18%) escalated to NIV, while 82% were maintained on HFNC. The median duration of HFNC was 30 hours (range 2-144 h). CONCLUSIONS: HFNC can provide adequate oxygenation for many patients with hypoxemic respiratory failure and may be an alternative to NIV for DNI patients.

Randomized, placebo-controlled clinical trial of an aerosolized ß2-agonist for treatment of acute lung injury.

RATIONALE: ß2-Adrenergic receptor agonists accelerate resolution of pulmonary edema in experimental and clinical studies. OBJECTIVES: This clinical trial was designed to test the hypothesis that an aerosolized ß2-agonist, albuterol, would improve clinical outcomes in patients with acute lung injury (ALI). METHODS: We conducted a multicenter, randomized, placebo-controlled clinical trial in which 282 patients with ALI receiving mechanical ventilation were randomized to receive aerosolized albuterol (5 mg) or saline placebo every 4 hours for up to 10 days. The primary outcome variable for the trial was ventilator-free days. MEASUREMENTS AND MAIN RESULTS: Ventilator-free days were not significantly different between the albuterol and placebo groups (means of 14.4 and 16.6 d, respectively; 95% confidence interval for the difference, -4.7 to 0.3 d; P = 0.087). Rates of death before hospital discharge were not significantly different between the albuterol and placebo groups (23.0 and 17.7%, respectively; 95%confidence interval for the difference,-4.0 to 14.7%;P = 0.30). In the subset of patients with shock before randomization, the number of ventilator-free days was lower with albuterol, although mortality was not different. Overall, heart rates were significantly higher in the albuterol group by approximately 4 beats/minute in the first 2 days after randomization, but rates of new atrial fibrillation (10% in both groups) and other cardiac dysrhythmias were not significantly different. CONCLUSIONS: These results suggest that aerosolized albuterol does not improve clinical outcomes in patients with ALI. Routine use of ß2-agonist therapy in mechanically ventilated patients with ALI cannot be recommended. Clinical trial registered with www.clinicaltrials.gov (NCT 00434993).

Sizing the lung of mechanically ventilated patients.

INTRODUCTION: This small observational study was motivated by our belief that scaling the tidal volume in mechanically ventilated patients to the size of the injured lung is safer and more 'physiologic' than scaling it to predicted body weight, i.e. its size before it was injured. We defined Total Lung Capacity (TLC) as the thoracic gas volume at an airway pressure of 40 cm H2O and tested if TLC could be inferred from the volume of gas that enters the lungs during a brief 'recruitment' maneuver. METHODS: Lung volume at relaxed end expiration (Vrel) as well as inspiratory capacity (IC), defined as the volume of gas that enters the lung during a 5 second inflation to 40 cm H2O, were measured in 14 patients with respiratory failure. TLC was defined as the sum of IC and Vrel. The dependence of IC and Vrel on body mass index (BMI), respiratory system elastance and plateau airway pressure was assessed. RESULTS: TLC was reduced to 59 ± 23% of that predicted. Vrel/TLC, which averaged 0.45 ± 0.11, was no different than the 0.47 ± 0.04 predicted during health in the supine posture. The greater than expected variability in observed Vrel/TLC was largely accounted for by BMI. Vrel and IC were correlated (r = 0.76). Taking BMI into account strengthened the correlation (r = 0.92). CONCLUSIONS: We conclude that body mass is a powerful determinant of lung volume and plateau airway pressure. Effective lung size can be easily estimated from a recruitment maneuver derived inspiratory capacity measurement and body mass index.