Increasing sweep gas flow reduces respiratory drive and dyspnea in non-intubated veno-arterial ECMO patients - a pilot study.

BACKGROUND.: Data on assessment and management of dyspnea in patients on veno-arterial extracorporeal membrane oxygenation (VA-ECMO) for cardiogenic shock are lacking. We hypothesized that increasing sweep gas flow through the VA-ECMO oxygenator may decrease dyspnea in non-intubated VA-ECMO patients exhibiting clinically significant dyspnea, with a parallel reduction in respiratory drive. METHODS.: Non-intubated, spontaneously breathing, supine patients on VA-ECMO for cardiogenic shock who presented with a visual analog dyspnea scale (dyspnea-VAS) ≥ 40/100 mm were included. Sweep gas flow was increased up to +6 L/min by three steps of +2 L/min each. Dyspnea was assessed with dyspnea-VAS and Multidimensional Dyspnea Profile. The respiratory drive was assessed by the electromyographic activity of the alae nasi and parasternal muscles. RESULTS.: We included 21 patients. On inclusion, median dyspnea-VAS was 50 ([interquartile range] 45-60) mm and sweep gas flow was 1.0 L/min (0.5-2.0). An increase in sweep gas flow significantly decreased dyspnea-VAS (50[45-60] at baseline vs 20[10-30] at 6L/min; p<0.001). The decrease in dyspnea was greater for the sensory component of dyspnea (-50%[43-75]) than for the affective and emotional components (-17%[0-25] and -12%[0-17], p<0.001). An increase in sweep gas flow significantly decreased electromyographic activity of the alae nasi and parasternal muscles (-23%[36-10] and -20[41-0], p<0.001). There was a significant correlation between the sweep gas flow and the dyspnea-VAS (r=-0.91 95%CI[-0.94, -0.87]), between the respiratory drive and the sensory component of dyspnea (r=0.29 95%CI[0.13, 0.44]), between the respiratory drive and the affective component of dyspnea (r=0.29 95%CI[0.02, 0.54]) and between the sweep gas flow and the alae nasi and parasternal (r=-0.31 95%CI[-0.44, -0.22] and r=-0.25 95%CI[-0.44, -0.16]). CONCLUSION.: In critically ill patients with VA-ECMO, an increase in sweep gas flow through the oxygenation membrane decreases dyspnea, possibly mediated by a decrease in respiratory drive.

Abatacept/Ruxolitinib and Screening for Concomitant Respiratory Muscle Failure to Mitigate Fatality of Immune-Checkpoint Inhibitor Myocarditis.

Immune-checkpoint-inhibitor (ICI)-associated myotoxicity involves the heart (myocarditis) and skeletal muscles (myositis), which frequently occur concurrently and are highly fatal. We report the results of a strategy that included identification of individuals with severe ICI myocarditis by also screening for and managing concomitant respiratory muscle involvement with mechanical ventilation, as well as treatment with the CTLA4 fusion protein abatacept and the JAK inhibitor ruxolitinib. Forty cases with definite ICI myocarditis were included with pathologic confirmation of concomitant myositis in the majority of patients. In the first 10 patients, using recommended guidelines, myotoxicity-related fatality occurred in 60%, consistent with historical controls. In the subsequent 30 cases, we instituted systematic screening for respiratory muscle involvement coupled with active ventilation and treatment using ruxolitinib and abatacept. The abatacept dose was adjusted using CD86 receptor occupancy on circulating monocytes. The myotoxicity-related fatality rate was 3.4% (1/30) in these 30 patients versus 60% in the first quartile (P < 0.0001). These clinical results are hypothesis-generating and need further evaluation. SIGNIFICANCE: Early management of respiratory muscle failure using mechanical ventilation and high-dose abatacept with CD86 receptor occupancy monitoring combined with ruxolitinib may be promising to mitigate high fatality rates in severe ICI myocarditis. See related commentary by Dougan, p. 1040. This article is highlighted in the In This Issue feature, p. 1027.

The terminal segment of the human phrenic nerve as a novel implantation site for diaphragm pacing electrodes: Anatomical and clinical description.

BACKGROUND: Diaphragm pacing allows certain ventilator-dependent patients to achieve weaning from mechanical ventilation. The reference method consists in implanting intrathoracic contact electrodes around the phrenic nerve during video-assisted thoracic surgery, which involves time-consuming phrenic nerve dissection with a risk of nerve damage. Identifying a phrenic segment suitable for dissection-free implantation of electrodes would constitute progress. STUDY DESIGN: This study characterizes a free terminal phrenic segment never fully described before. We conducted a cadaver study (n = 14) and a clinical observational study during thoracic procedures (n = 54). RESULTS: A free terminal phrenic segment was observed on both sides in 100% of cases, "jumping" from the pericardium to the diaphragm and measuring 60 mm [95% confidence interval; 48-63] and 72.5 mm [65-82] (right left, respectively; p = 0.0038; cadaver study). This segment rolled up on itself at end-expiration and became unravelled and elongated with diaphragm descent (clinical study). Three categories of fat pads were defined (type 1: pericardiophrenic bundle free of surrounding fat; type 2: single fatty fringe leaving the phrenic nerve visible until diaphragmatic entry; type 3: multiple fatty fringes masking the site of penetration of the phrenic nerve) that depended on body mass index (p = 0.001, clinical study). Hematoxylin-eosin and toluidine blue staining (cadaver study) showed that all of the phrenic fibers in the distal, pre-branching part of the terminal segment were contained within a single epineurium containing a variable number of fascicles (right: 1 [95%CI 0.65-4.01]; left 5 [3.37-7.63]; p = 0.03). CONCLUSION: Diaphragm pacing through periphrenic electrodes positioned on the terminal phrenic segment should be tested.

Focus on renal blood flow in mechanically ventilated patients with SARS-CoV-2: a prospective pilot study.

Mechanically ventilated patients with ARDS due to the severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) seem particularly susceptible to AKI. Our hypothesis was that the renal blood flow could be more compromised in SARS-CoV-2 patients than in patients with "classical" ARDS. We compared the renal resistivity index (RRI) and the renal venous flow (RVF) in ARDS patients with SARS-CoV-2 and in ARDS patients due to other etiologies. Prospective, observational pilot study performed on 30 mechanically ventilated patients (15 with SARS-COV-2 ARDS and 15 with ARDS). Mechanical ventilation settings included constant-flow controlled ventilation, a tidal volume of 6 ml/kg of ideal body weight and the PEEP level titrated to the lowest driving pressure. Ultrasound Doppler measurements of RRI and RVF pattern were performed in each patient. Patients with SARS-COV-2 ARDS had higher RRI than patients with ARDS (0.71[0.67-0.78] vs 0.64[0.60-0.74], p = 0.04). RVF was not-continuous in 9/15 patients (71%) in the SARS-COV-2 ARDS group and in and 5/15 (33%) in the ARDS group (p = 0.27). A linear correlation was found between PEEP and RRI in patients with SARS-COV-2 ARDS (r2 = 0.31; p = 0.03) but not in patients with ARDS. Occurrence of AKI was 53% in patients with SARS-COV-2 ARDS and 33% in patients with ARDS (p = 0.46). We found a more pronounced impairment in renal blood flow in mechanically ventilated patients with SARS-COV-2 ARDS, compared with patients with "classical" ARDS.

Clinical features and outcome of patients with primary central nervous system lymphoma admitted to the intensive care unit: a French national expert center experience.

INTRODUCTION: To describe the reasons for intensive care unit (ICU) admission and to evaluate the outcomes and prognostic factors of patients with primary central nervous system lymphoma (PCNSL) admitted to the ICU. PATIENTS AND METHODS: Retrospective observational cohort study of 101 PCNSL patients admitted to 3 ICUs over a two-decade period. RESULTS: Acute respiratory failure, mainly secondary to aspiration pneumonia and Pneumocystis jirovecii pneumonia, was the leading reason for ICU admission (33%). Aspiration pneumonia was more common in patients with brainstem tumor (67% vs. 0%, p < 0.001), whereas patients with intracranial hypertension were more frequently admitted for coma without seizures (61% vs. 9%, p = 0.004). Hospital and 6-month mortality were 47% and 53%, respectively. In multivariate analysis, admission for coma without seizures (OR 7.28), cancer progression (OR 3.47), mechanical ventilation (OR 6.58) and vasopressors (OR 4.07) were associated with higher 6-month mortality. Karnofsky performance status prior to ICU admission was independently associated with lower 6-month mortality (OR 0.96). DISCUSSION: Six-month survival of PCNSL patients admitted to the ICU appears to be relatively favorable (around 50%) and the presence of PCNSL alone is not a relevant criterion for ICU refusal. Predictive factors of mortality may help clinicians to make optimal triage decisions.

One-year survival of patients with high-grade glioma discharged alive from the intensive care unit.

INTRODUCTION: Only limited data are available regarding the long-term prognosis of patients with high-grade glioma discharged alive from the intensive care unit. We sought to quantify 1-year mortality and evaluate the association between mortality and (1) functional status, and (2) management of anticancer therapy in patients with high-grade glioma discharged alive from the intensive care unit. PATIENTS AND METHODS: Retrospective observational cohort study of patients with high-grade glioma admitted to two intensive care units between January 2009 and June 2018. Functional status was assessed by the Karnofsky Performance Status. Anticancer therapy after discharge was classified as (1) continued (unchanged), (2) modified (changed or stopped), or (3) initiated (for newly diagnosed disease). RESULTS: Ninety-one high-grade glioma patients (73% of whom had glioblastoma) were included and 78 (86%) of these patients were discharged alive from the intensive care unit. Anticancer therapy was continued, modified, and initiated in 41%, 42%, and 17% of patients, respectively. Corticosteroid therapy at the time of ICU admission [odds ratio (OR) 0.07] and cancer progression (OR 0.09) was independently associated with continuation of anticancer therapy. The mortality rate 1 year after ICU admission was 73%. On multivariate analysis, continuation of anticancer therapy (OR 0.18) and Karnofsky performance status on admission (OR 0.90) were independently associated with lower 1-year mortality. CONCLUSION: The presence of high-grade glioma is not sufficient to justify refusal of intensive care unit admission. Performance status and continuation of anticancer therapy are associated with higher survival after intensive care unit discharge. PREVIOUS PRESENTATION: Preliminary results were presented at the most recent congress of the French Intensive Care Society, Paris, 2019.

Correction to: Effect of PEEP decremental on respiratory mechanics, gas exchange, pulmonary regional ventilation, and hemodynamics in patients with SARS-Cov-2-associated Acute Respiratory Distress Syndrome.

An amendment to this paper has been published and can be accessed via the original article.

Increased mortality in patients with severe SARS-CoV-2 infection admitted within seven days of disease onset.

PURPOSE: Coronavirus disease 2019 (COVID-19) is creating an unprecedented healthcare crisis. Understanding the determinants of mortality is crucial to optimise intensive care unit (ICU) resource use and to identify targets for improving survival. METHODS: In a multicentre retrospective study, we included 379 COVID-19 patients admitted to four ICUs between 20 February and 24 April 2020 and categorised according to time from disease onset to ICU admission. A Cox proportional-hazards model identified factors associated with 28-day mortality. RESULTS: Median age was 66 years (53-68) and 292 (77%) were men. The main comorbidities included obesity and overweight (67%), hypertension (49.6%) and diabetes (30.1%). Median time from disease onset (i.e., viral symptoms) to ICU admission was 8 (6-11) days (missing for three); 161 (42.5%) patients were admitted within a week of disease onset, 173 (45.6%) between 8 and 14 days, and 42 (11.1%) > 14 days after disease onset; day 28 mortality was 26.4% (22-31) and decreased as time from disease onset to ICU admission increased, from 37 to 21% and 12%, respectively. Patients admitted within the first week had higher SOFA scores, more often had thrombocytopenia or acute kidney injury, had more limited radiographic involvement, and had significantly higher blood IL-6 levels. Age, COPD, immunocompromised status, time from disease onset, troponin concentration, and acute kidney injury were independently associated with mortality. CONCLUSION: The excess mortality in patients admitted within a week of disease onset reflected greater non-respiratory severity. Therapeutic interventions against SARS-CoV-2 might impact different clinical endpoints according to time since disease onset.

Survival of amyotrophic lateral sclerosis patients after admission to the intensive care unit for acute respiratory failure: an observational cohort study.

PURPOSE: Amyotrophic lateral sclerosis (ALS) entails a risk of acute respiratory failure (ARF). The decision to admit such patients to the intensive care unit (ICU) is difficult given the inexorable prognosis of ALS. To fuel this discussion, this study describes the ICU and post-ICU survival of ALS-related ARF. MATERIAL AND METHODS: Retrospective cohort analysis over 10 years (university hospital setting, ALS reference center). RESULTS: Of 90 patients (66 men, median age: 67 [IQR 59-71], median interval since ALS diagnosis: 26.5 months [14-53], ALSFRS-R: 19 [12-30], bulbar signs 73%), 48 were managed by noninvasive ventilation (NIV) only, 7 were already tracheotomized upon admission, 12 were tracheotomized during the ICU stay (advance care planning project), 18 were already intubated before admission, 5 received oxygen and physiotherapy only. Median ICU stay was 4 days [2-9] with 20% mortality. Median hospital stay was 10 days [5-22] with 33% mortality. The 3-month and one year mortality wer 46% and 71%. Hospital mortality was higher in patients with more severe respiratory acidosis and higher simplified acute physiology scores on admission. CONCLUSIONS: The prognosis of ALS-related ARF requiring ICU admission resembles that of ARF complicating other conditions with high short-term mortality (e.g. lung cancer).

High-flow nasal oxygen versus noninvasive ventilation in adult patients with cystic fibrosis: a randomized crossover physiological study.

BACKGROUND: Noninvasive ventilation (NIV) is the first-line treatment of adult patients with exacerbations of cystic fibrosis (CF). High-flow nasal oxygen therapy (HFNT) might benefit patients with hypoxemia and can reduce physiological dead space. We hypothesized that HFNT and NIV would similarly reduce work of breathing and improving breathing pattern in CF patients. Our objective was to compare the effects of HFNT versus NIV in terms of work of breathing, assessed noninvasively by the thickening fraction of the diaphragm (TFdi, measured with ultrasound), breathing pattern, transcutaneous CO2 (PtcCO2), hemodynamics, dyspnea and comfort. METHODS: Adult CF patients who had been stabilized after requiring ventilatory support for a few days were enrolled and ventilated with HFNT and NIV for 30 min in crossover random order. RESULTS: Fifteen patients were enrolled. Compared to baseline, HFNT, but not NIV, reduced respiratory rate (by 3 breaths/min, p = 0.01) and minute ventilation (by 2 L/min, p = 0.01). Patients also took slightly larger tidal volumes with HFNT compared to NIV (p = 0.02). TFdi per breath was similar under the two techniques and did not change from baseline. MAP increased from baseline with NIV and compared to HFNT (p ≤ 0.01). Comfort was poorer with the application of both HFNT and NIV than baseline. No differences were found for heart rate, SpO2, PtcCO2 or dyspnea. CONCLUSIONS: In adult CF patients stabilized after indication for ventilatory support, HFNT and NIV have similar effects on diaphragmatic work per breath, but high-flow therapy confers additional physiological benefits by decreasing respiratory rate and minute ventilation. CLINICAL TRIAL REGISTRATION: Ethics Committee of St. Michael's Hospital (REB #14-338) and clinicaltrial.gov (NCT02262871).

Update in Critical Care 2015.

This review documents important progress made in 2015 in the field of critical care. Significant advances in 2015 included further evidence for early implementation of low tidal volume ventilation as well as new insights into the role of open lung biopsy, diaphragmatic dysfunction, and a potential mechanism for ventilator-induced fibroproliferation. New therapies, including a novel low-flow extracorporeal CO2 removal technique and mesenchymal stem cell-derived microparticles, have also been studied. Several studies examining the role of improved diagnosis and prevention of ventilator-associated pneumonia also showed relevant results. This review examines articles published in the American Journal of Respiratory and Critical Care Medicine and other major journals that have made significant advances in the field of critical care in 2015.

Non-invasive ventilation in immunocompromised patients with acute hypoxemic respiratory failure.

The survival rate of immunocompromised patients has improved over the past decades in light of remarkable progress in diagnostic and therapeutic options. Simultaneously, there has been an increase in the number of immunocompromised patients with life threatening complications requiring intensive care unit (ICU) treatment. ICU admission is necessary in up to 15% of patients with acute leukemia and 20% of bone marrow transplantation recipients, and the main reason for ICU referral in this patient population is acute hypoxemic respiratory failure, which is associated with a high mortality rate, particularly in patients requiring endotracheal intubation. The application of non-invasive ventilation (NIV), and thus the avoidance of endotracheal intubation and invasive mechanical ventilation with its side effects, appears therefore of great importance in this patient population. Early trials supported the benefits of NIV in these settings, and the 2011 Canadian guidelines for the use of NIV in critical care settings suggest the use of NIV in immune-compromised patients with a grade 2B recommendation. However, the very encouraging results from initial seminal trials were not confirmed in subsequent observational and randomized clinical studies, questioning the beneficial effect of NIV in immune-compromised patients. Based on these observations, a French group led by Azoulay decided to assess whether early intermittent respiratory support with NIV had a role in reducing the mortality rate of immune-compromised patients with non-hypercapnic hypoxemic respiratory failure developed in less than 72 h, and hence conducted a multicenter randomized controlled trial (RCT) in experienced ICUs in France. This perspective reviews the findings from their RCT in the context of the current critical care landscape, and in light of recent results from other trials focused on the early management of acute hypoxemic respiratory failure.

Clinical features and outcomes in patients with disseminated toxoplasmosis admitted to intensive care: a multicenter study.

BACKGROUND: Characteristics and outcomes of adult patients with disseminated toxoplasmosis admitted to the intensive care unit (ICU) have rarely been described. METHODS: We performed a retrospective study on consecutive adult patients with disseminated toxoplasmosis who were admitted from January 2002 through December 2012 to the ICUs of 14 university-affiliated hospitals in France. Disseminated toxoplasmosis was defined as microbiological or histological evidence of disease affecting >1 organ in immunosuppressed patients. Isolated cases of cerebral toxoplasmosis were excluded. Clinical data on admission and risk factors for 60-day mortality were collected. RESULTS: Thirty-eight patients were identified during the study period. Twenty-two (58%) had received an allogeneic hematopoietic stem cell transplant (median, 61 [interquartile range {IQR}, 43-175] days before ICU admission), 4 (10%) were solid organ transplant recipients, and 10 (27%) were infected with human immunodeficiency virus (median CD4 cell count, 14 [IQR, 6-33] cells/µL). The main indications for ICU admission were acute respiratory failure (89%) and shock (53%). The 60-day mortality rate was 82%. Allogeneic hematopoietic stem cell transplant (hazard ratio [HR] = 2.28; 95% confidence interval [CI], 1.05-5.35; P = .04) and systolic cardiac dysfunction (HR = 3.54; 95% CI, 1.60-8.10; P < .01) within 48 hours of ICU admission were associated with mortality. CONCLUSIONS: Severe disseminated toxoplasmosis leading to ICU admission has a poor prognosis. Recipients of allogeneic hematopoietic stem cell transplant appear to have the highest risk of mortality. We identified systolic cardiac dysfunction as a major determinant of outcome. Strategies aimed at preventing this fatal opportunistic infection may improve outcomes.