Post-insufflation diaphragm contractions in patients receiving various modes of mechanical ventilation.

BACKGROUND: During mechanical ventilation, post-insufflation diaphragm contractions (PIDCs) are non-physiologic and could be injurious. PIDCs could be frequent during reverse-triggering, where diaphragm contractions follow the ventilator rhythm. Whether PIDCs happens with different modes of assisted ventilation is unknown. In mechanically ventilated patients with hypoxemic respiratory failure, we aimed to examine whether PIDCs are associated with ventilator settings, patients' characteristics or both. METHODS: One-hour recordings of diaphragm electromyography (EAdi), airway pressure and flow were collected once per day for up to five days from intubation until full recovery of diaphragm activity or death. Each breath was classified as mandatory (without-reverse-triggering), reverse-triggering, or patient triggered. Reverse triggering was further subclassified according to EAdi timing relative to ventilator cycle or reverse triggering leading to breath-stacking. EAdi timing (onset, offset), peak and neural inspiratory time (Tineuro) were measured breath-by-breath and compared to the ventilator expiratory time. A multivariable logistic regression model was used to investigate factors independently associated with PIDCs, including EAdi timing, amplitude, Tineuro, ventilator settings and APACHE II. RESULTS: Forty-seven patients (median[25%-75%IQR] age: 63[52-77] years, BMI: 24.9[22.9-33.7] kg/m2, 49% male, APACHE II: 21[19-28]) contributed 2 ± 1 recordings each, totaling 183,962 breaths. PIDCs occurred in 74% of reverse-triggering, 27% of pressure support breaths, 21% of assist-control breaths, 5% of Neurally Adjusted Ventilatory Assist (NAVA) breaths. PIDCs were associated with higher EAdi peak (odds ratio [OR][95%CI] 1.01[1.01;1.01], longer Tineuro (OR 37.59[34.50;40.98]), shorter ventilator inspiratory time (OR 0.27[0.24;0.30]), high peak inspiratory flow (OR 0.22[0.20;0.26]), and small tidal volumes (OR 0.31[0.25;0.37]) (all P ≤ 0.008). NAVA was associated with absence of PIDCs (OR 0.03[0.02;0.03]; P < 0.001). Reverse triggering was characterized by lower EAdi peak than breaths triggered under pressure support and associated with small tidal volume and shorter set inspiratory time than breaths triggered under assist-control (all P < 0.05). Reverse triggering leading to breath stacking was characterized by higher peak EAdi and longer Tineuro and associated with small tidal volumes compared to all other reverse-triggering phenotypes (all P < 0.05). CONCLUSIONS: In critically ill mechanically ventilated patients, PIDCs and reverse triggering phenotypes were associated with potentially modifiable factors, including ventilator settings. Proportional modes like NAVA represent a solution abolishing PIDCs.

Weaning from mechanical ventilation in the operating room: a systematic review.

BACKGROUND: Postoperative pulmonary complications (PPCs) are associated with postoperative mortality and prolonged hospital stay. Although intraoperative mechanical ventilation (MV) is a risk factor for PPCs, strategies addressing weaning from MV are understudied. In this systematic review, we evaluated weaning strategies and their effects on postoperative pulmonary outcomes. METHODS: Our protocol was registered on PROSPERO (CRD42022379145). Eligible studies included randomised controlled trials and observational studies of adults weaned from MV in the operating room. Primary outcomes included atelectasis and oxygenation; secondary outcomes included lung volume changes and PPCs. Risk of bias was assessed using the Cochrane Risk of Bias (RoB2) tool, and quality of evidence with the GRADE framework. RESULTS: Screening identified 14 randomised controlled trials including 1719 patients; seven studies were limited to the weaning phase and seven included interventions not restricted to the weaning phase. Strategies combining pressure support ventilation (PSV) with positive end-expiratory pressure (PEEP) and low fraction of inspired oxygen (FiO2) improved atelectasis, oxygenation, and lung volumes. Low FiO2 improved atelectasis and oxygenation but might not improve lung volumes. A fixed-PEEP strategy led to no improvement in oxygenation or atelectasis; however, individualised PEEP with low FiO2 improved oxygenation and might be associated with reduced PPCs. Half of included studies are of moderate or high risk of bias; the overall quality of evidence is low. CONCLUSIONS: There is limited research evaluating weaning from intraoperative MV. Based on low-quality evidence, PSV, individualised PEEP, and low FiO2 may be associated with reduced postoperative pulmonary outcomes. SYSTEMATIC REVIEW PROTOCOL: PROSPERO (CRD42022379145).

Lung Recruitment Assessed by Electrical Impedance Tomography (RECRUIT): A Multicenter Study of COVID-19 Acute Respiratory Distress Syndrome.

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. Clinical trial registered with www.clinicaltrials.gov (NCT04460859).

Pilot investigation of an electronic pillbox at a community opioid treatment program.

Background: Opioid treatment programs (OTPs) permit patients to ingest daily methadone doses unsupervised and away from the clinic, a strategy that enhances treatment access and convenience but has the potential for mismanagement.Objective: This retrospective review, conducted during the COVID-19 pandemic (5/2020-1/2022), evaluates the feasibility and acceptability of a commercially available electronic pillbox to safely administer methadone take-home tablets in a large community-based OTP (census >500 people).Methods: Study participants (n = 24; 54% male, 46% female; M age = 63 years) had recently received more take-homes per visit to support national social distancing directives, and were instructed that they could maintain these privileges by agreeing to use the pillbox.Results: Results demonstrate good demand feasibility as most participants (71%) agreed to use the pillbox. Good implementation feasibility was observed through safe and reliable delivery of most take-home tablets, with a staff support line to resolve technical issues. Acceptability was modest as six participants (25%) requested to return the pillbox despite losing some take-home privileges.Conclusion: Results support continued use and study of the electronic pillbox to safely deliver and increase access to methadone take-home doses.

The association between nutritional risk index and ICU outcomes across hematologic malignancy patients with acute respiratory failure.

Patients with hematological malignancies (HM) are at risk of acute respiratory failure (ARF). Malnutrition, a common association with HM, has the potential to influence ICU outcomes. Geriatric nutritional risk index (G-NRI) is a score derived from albumin and weight, which reflects risk of protein-energy malnutrition. We evaluated the association between G-NRI at ICU admission and ICU mortality in HM patients with ARF. We conducted a single center retrospective study of ventilated HM patients between 2014 and 2018. We calculated G-NRI for all patients using their ICU admission albumin and weight. Our primary outcome was ICU mortality. Secondary outcomes included duration of mechanical ventilation and ICU length of stay. Two hundred eighty patients were admitted to the ICU requiring ventilation. Median age was 62 years (IQR 51-68), 42% (n = 118) were females, and median SOFA score was 11 (IQR 9-14). The most common type of HM was acute leukemia (54%) and 40% underwent hematopoietic cell transplant. Median G-NRI was 87 (IQR 79-99). ICU mortality was 51% (n = 143) with a median duration of ventilation of 4 days (IQR 2-7). Mortality across those at severe malnutrition (NRI < 83.5) was 59% (65/111) compared to 46% (76/164) across those with moderate-no risk (p = 0.047). On multivariable analysis, severe NRI (OR 2.34, 95% CI 1.04-5.27, p = 0.04) was significantly associated with ICU mortality. In this single center, exploratory study, severe G-NRI was prognostic of ICU mortality in HM patients admitted with respiratory failure.

"I'm a Survivor": Perceptions of Chronic Disease and Survivorship Among Individuals in Long-Term Remission from Opioid Use Disorder.

BACKGROUND: While opioid use disorder (OUD) is prevalent, little is known about what patients with OUD in sustained remission think about the chronic disease model of OUD and their perspectives of the cause, course, and ongoing treatment needs of their OUD. OBJECTIVE: To (1) examine patient perceptions of the chronic disease model of addiction and disease identity and (2) use an explanatory model framework to explore how these perceptions inform ongoing treatment needs and help maintain abstinence. DESIGN: Qualitative study of a cross-sectional cohort of patients with OUD in long-term sustained remission currently receiving methadone or buprenorphine. Participants completed a single in-depth, semi-structured individual interview. PARTICIPANTS: Twenty adults were recruited from two opioid treatment programs and two office-based opioid treatment programs in Baltimore, MD. Half of the participants were Black, had a median (IQR) age of 46.5 (43-52) years and the median (IQR) time since the last non-prescribed opioid was 12 (8-15) years. APPROACH: Hybrid deductive-inductive thematic analysis of the transcribed interviews. KEY RESULTS: Some participants described a chronic OUD disease identity where they continue to live with OUD. Participants who maintain an OUD identity describe inherent traits or predetermination of developing OUD. Maintaining a disease identity helps them remain vigilant against returning to drug use. Others described a post-OUD/survivor identity where they no longer felt they had OUD, but the experience remains. Each perspective informed attitudes about continued treatment with methadone or buprenorphine and strategies to remain in remission. CONCLUSIONS: The identity that people with OUD in sustained remission maintain was the lens through which they viewed other aspects of their OUD including cause and ongoing treatment needs. An alternative, post-OUD/survivorship model emerged or was accepted by participants who did not identify as currently having OUD. Understanding patient perspectives of OUD identity might improve patient-centered care and improve outcomes.

Phrenic Nerve Block and Respiratory Effort in Pigs and Critically Ill Patients with Acute Lung Injury.

BACKGROUND: Strong spontaneous inspiratory efforts can be difficult to control and prohibit protective mechanical ventilation. Instead of using deep sedation and neuromuscular blockade, the authors hypothesized that perineural administration of lidocaine around the phrenic nerve would reduce tidal volume (VT) and peak transpulmonary pressure in spontaneously breathing patients with acute respiratory distress syndrome. METHODS: An established animal model of acute respiratory distress syndrome with six female pigs was used in a proof-of-concept study. The authors then evaluated this technique in nine mechanically ventilated patients under pressure support exhibiting driving pressure greater than 15 cm H2O or VT greater than 10 ml/kg of predicted body weight. Esophageal and transpulmonary pressures, electrical activity of the diaphragm, and electrical impedance tomography were measured in pigs and patients. Ultrasound imaging and a nerve stimulator were used to identify the phrenic nerve, and perineural lidocaine was administered sequentially around the left and right phrenic nerves. RESULTS: Results are presented as median [interquartile range, 25th to 75th percentiles]. In pigs, VT decreased from 7.4 ml/kg [7.2 to 8.4] to 5.9 ml/kg [5.5 to 6.6] (P < 0.001), as did peak transpulmonary pressure (25.8 cm H2O [20.2 to 27.2] to 17.7 cm H2O [13.8 to 18.8]; P < 0.001) and driving pressure (28.7 cm H2O [20.4 to 30.8] to 19.4 cm H2O [15.2 to 22.9]; P < 0.001). Ventilation in the most dependent part decreased from 29.3% [26.4 to 29.5] to 20.1% [15.3 to 20.8] (P < 0.001). In patients, VT decreased (8.2 ml/ kg [7.9 to 11.1] to 6.0 ml/ kg [5.7 to 6.7]; P < 0.001), as did driving pressure (24.7 cm H2O [20.4 to 34.5] to 18.4 cm H2O [16.8 to 20.7]; P < 0.001). Esophageal pressure, peak transpulmonary pressure, and electrical activity of the diaphragm also decreased. Dependent ventilation only slightly decreased from 11.5% [8.5 to 12.6] to 7.9% [5.3 to 8.6] (P = 0.005). Respiratory rate did not vary. Variables recovered 1 to 12.7 h [6.7 to 13.7] after phrenic nerve block. CONCLUSIONS: Phrenic nerve block is feasible, lasts around 12 h, and reduces VT and driving pressure without changing respiratory rate in patients under assisted ventilation.

Providing respiratory and ventilation care in the face of shifting evidence: current opinion in critical care.

PURPOSE OF REVIEW: To review the clinical problem and noninvasive treatments of hypoxemia in critically-ill patients with coronavirus disease 2019 pneumonia and describe recent advances in evidence supporting bedside decision making. RECENT FINDINGS: High-flow nasal oxygen and noninvasive ventilation, along with awake prone positioning are potentially helpful therapies for acute hypoxemic respiratory failure. High-flow nasal oxygen therapy has been widely implemented as a form of oxygen support supported by prepandemic randomized controlled trials showing possible benefit over noninvasive ventilation. Given the sheer volume of patients, noninvasive ventilation was often required, and based on a well conducted randomized controlled trial there was a developing role for helmet-interface noninvasive. Coupled with noninvasive supports, the use of awake prone positioning demonstrated physiological benefits, but randomized controlled trial data did not demonstrate clear outcome superiority. SUMMARY: The use of noninvasive oxygen strategies and our understanding of the proposed mechanisms are evolving. Variability in patient severity and physiology may dictate a personalized approach to care. High-flow nasal oxygen may be paired with awake and spontaneously breathing prone-positioning to optimize oxygen and lung mechanics but requires further insight before widely applying to clinical practice.

Dyspnoea and respiratory muscle ultrasound to predict extubation failure.

BACKGROUND: This study investigated dyspnoea intensity and respiratory muscle ultrasound early after extubation to predict extubation failure. METHODS: The study was conducted prospectively in two intensive care units in France and Canada. Patients intubated for at least 48 h were studied within 2 h after an extubation following a successful spontaneous breathing trial. Dyspnoea was evaluated by a dyspnoea visual analogue scale (Dyspnoea-VAS) ranging from 0 to 10 and the Intensive Care Respiratory Distress Observational Scale (IC-RDOS). The ultrasound thickening fraction of the parasternal intercostal and the diaphragm was measured; limb muscle strength was evaluated using the Medical Research Council (MRC) score (range 0-60). RESULTS: Extubation failure occurred in 21 out of 122 enrolled patients (17%). The median (interquartile range (IQR)) Dyspnoea-VAS and IC-RDOS were higher in patients with extubation failure versus success: 7 (4-9) versus 3 (1-5) (p<0.001) and 3.7 (1.8-5.8) versus 1.7 (1.5-2.1) (p<0.001), respectively. The median (IQR) ratio of parasternal intercostal muscle to diaphragm thickening fraction was significantly higher and MRC was lower in patients with extubation failure compared with extubation success: 0.9 (0.4-2.1) versus 0.3 (0.2-0.5) (p<0.001) and 45 (36-50) versus 52 (44-60) (p=0.012), respectively. The thickening fraction of the parasternal intercostal and its ratio to diaphragm thickening showed the highest area under the receiver operating characteristic curve (AUC) for an early prediction of extubation failure (0.81). AUCs of Dyspnoea-VAS and IC-RDOS reached 0.78 and 0.74, respectively. CONCLUSIONS: Respiratory muscle ultrasound and dyspnoea measured within 2 h after extubation predict subsequent extubation failure.

Diaphragm echodensity in mechanically ventilated patients: a description of technique and outcomes.

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.

Duration of diaphragmatic inactivity after endotracheal intubation of critically ill patients.

BACKGROUND: In patients intubated for mechanical ventilation, prolonged diaphragm inactivity could lead to weakness and poor outcome. Time to resume a minimal diaphragm activity may be related to sedation practice and patient severity. METHODS: Prospective observational study in critically ill patients. Diaphragm electrical activity (EAdi) was continuously recorded after intubation looking for resumption of a minimal level of diaphragm activity (beginning of the first 24 h period with median EAdi > 7 µV, a threshold based on literature and correlations with diaphragm thickening fraction). Recordings were collected until full spontaneous breathing, extubation, death or 120 h. A 1 h waveform recording was collected daily to identify reverse triggering. RESULTS: Seventy-five patients were enrolled and 69 analyzed (mean age ± standard deviation 63 ± 16 years). Reasons for ventilation were respiratory (55%), hemodynamic (19%) and neurologic (20%). Eight catheter disconnections occurred. The median time for resumption of EAdi was 22 h (interquartile range 0-50 h); 35/69 (51%) of patients resumed activity within 24 h while 4 had no recovery after 5 days. Late recovery was associated with use of sedative agents, cumulative doses of propofol and fentanyl, controlled ventilation and age (older patients receiving less sedation). Severity of illness, oxygenation, renal and hepatic function, reason for intubation were not associated with EAdi resumption. At least 20% of patients initiated EAdi with reverse triggering. CONCLUSION: Low levels of diaphragm electrical activity are common in the early course of mechanical ventilation: 50% of patients do not recover diaphragmatic activity within one day. Sedatives are the main factors accounting for this delay independently from lung or general severity. Trial Registration ClinicalTrials.gov (NCT02434016). Registered on April 27, 2015. First patients enrolled June 2015.

Potential for Lung Recruitment Estimated by the Recruitment-to-Inflation Ratio in Acute Respiratory Distress Syndrome. A Clinical Trial.

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).

When to transfuse your acute care patient? A narrative review of the risk of anemia and red blood cell transfusion based on clinical trial outcomes.

This narrative review critically evaluates the evidence for risk of anemia and red blood cell (RBC) transfusion. For this purpose, it assesses large prospective randomized-controlled trials (RCTs) in medical, surgical, and critical care patient populations in which the impact of specific hemoglobin transfusion thresholds are compared. In these trials, the risks of anemia relative to those of RBC transfusion are assessed. The results of published systematic reviews and meta-analyses are also discussed. Lastly, recommendations for patient blood management and treatment of anemia are explored. The main conclusion of this review emphasizes that the decision to transfuse RBCs is complex and depends on the interaction between multiple factors including the balance between the risk of anemia and the risk of RBC transfusion, existing patient comorbidities, and medical and surgical exposures. The transfusion thresholds recommended by current guidelines vary for medical and surgical patient populations. Guidelines suggesting specific transfusion thresholds for different patient populations should be viewed as a starting point for making an informed decision about RBC transfusion. Alternatives to transfusion (i.e., patient blood management), biomarkers of anemia-induced tissue hypoxia, and transfusion alternatives should continue to be evaluated in large RCTs, with the goal of improving event-free survival in critically ill and perioperative patients.

RéSUMé: Ce compte rendu narratif évalue de façon critique les données probantes concernant le risque de l'anémie et de la transfusion d'érythrocytes. Pour ce faire, nous avons évalué des études randomisées contrôlées (ERC) prospectives de grande envergure réalisées auprès de populations de patients médicaux, chirurgicaux et de soins intensifs dans lesquelles l'impact de seuils spécifiques de transfusion d'hémoglobine est comparé. Dans ces études, les risques de l'anémie sont comparés aux risques de la transfusion d'érythrocytes. Les résultats des comptes rendus systématiques et méta-analyses publiés sont également présentés. Enfin, les recommandations concernant la gestion du sang des patients et le traitement de l'anémie sont explorées. La conclusion principale de ce compte rendu souligne que la décision de transfuser des érythrocytes est complexe et dépend de l'interaction de plusieurs facteurs, notamment de l'équilibre entre le risque de l'anémie et le risque de la transfusion d'érythrocytes, les comorbidités existantes du patient, et les risques médicaux et chirurgicaux. Les seuils de transfusion recommandés par les directives actuelles sont différents pour les populations de patients médicaux et chirurgicaux. Les directives proposant des seuils de transfusion spécifiques en fonction des différentes populations de patients devraient être considérées comme point de départ pour prendre une décision informée concernant la transfusion d'érythrocytes. Les alternatives à la transfusion (c.-à-d. la gestion du sang des patients), les biomarqueurs d'une hypoxie tissulaire induite par l'anémie et les alternatives à la transfusion devraient continuer à être évalués dans des ERC d'envergure, avec pour but l'amélioration de la survie sans complication des patients en état critique et périopératoires.

Emergent airway management of the critically ill patient: current opinion in critical care.

PURPOSE OF REVIEW: To describe techniques to facilitate safe intubation in critically ill patients. RECENT FINDINGS: Despite advances in the treatment of critically ill patients, endotracheal intubation remains a high-risk procedure associated with complications that can lead to appreciable morbidity and mortality. In addition to the usual anatomical factors that can predict a difficult intubation, incorporating pathophysiological considerations and crisis resource management may enhance safety and mitigate risk. Enhancing preoxygenation with high-flow oxygen or noninvasive ventilation, the early use of intravenous fluids and/or vasopressors to prevent hypotension and videolaryngoscopy for first pass success are all promising additions to airway management.Facilitating intubation by either sedation with paralysis or allowing patients to continue to breathe spontaneously are reasonable options for airway management. These approaches have potential advantages and disadvantages. SUMMARY: Recognizing the unique challenges of endotracheal intubation in critically ill patients is paramount in limiting further deterioration during this high-risk procedure. A safe approach to intubation focuses on recognizing risk factors that predict challenges in achieving an optimal view of the glottis, maintaining optimal oxygenation, and minimizing the risks and benefits of sedation/induction strategies that are meant to facilitate intubation and avoid clinical deterioration.

Optimal Ventilator Strategies in Acute Respiratory Distress Syndrome.

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.

Mechanical Ventilation-induced Diaphragm Atrophy Strongly Impacts Clinical Outcomes.

RATIONALE: Diaphragm dysfunction worsens outcomes in mechanically ventilated patients, but the clinical impact of potentially preventable changes in diaphragm structure and function caused by mechanical ventilation is unknown. OBJECTIVES: To determine whether diaphragm atrophy developing during mechanical ventilation leads to prolonged ventilation. METHODS: Diaphragm thickness was measured daily by ultrasound in adults requiring invasive mechanical ventilation; inspiratory effort was assessed by thickening fraction. The primary outcome was time to liberation from ventilation. Secondary outcomes included complications (reintubation, tracheostomy, prolonged ventilation, or death). Associations were adjusted for age, severity of illness, sepsis, sedation, neuromuscular blockade, and comorbidity. MEASUREMENTS AND MAIN RESULTS: Of 211 patients enrolled, 191 had two or more diaphragm thickness measurements. Thickness decreased more than 10% in 78 patients (41%) by median Day 4 (interquartile range, 3-5). Development of decreased thickness was associated with a lower daily probability of liberation from ventilation (adjusted hazard ratio, 0.69; 95% confidence interval [CI], 0.54-0.87; per 10% decrease), prolonged ICU admission (adjusted duration ratio, 1.71; 95% CI, 1.29-2.27), and a higher risk of complications (adjusted odds ratio, 3.00; 95% CI, 1.34-6.72). Development of increased thickness (n = 47; 24%) also predicted prolonged ventilation (adjusted duration ratio, 1.38; 95% CI, 1.00-1.90). Decreasing thickness was related to abnormally low inspiratory effort; increasing thickness was related to excessive effort. Patients with thickening fraction between 15% and 30% (similar to breathing at rest) during the first 3 days had the shortest duration of ventilation. CONCLUSIONS: Diaphragm atrophy developing during mechanical ventilation strongly impacts clinical outcomes. Targeting an inspiratory effort level similar to that of healthy subjects at rest might accelerate liberation from ventilation.