Respiratory drive heterogeneity associated with systemic inflammation and vascular permeability in acute respiratory distress syndrome

BACKGROUND

In acute respiratory distress syndrome (ARDS), respiratory drive often differs among patients with similar clinical characteristics. Readily observable factors like acid-base state, oxygenation, mechanics, and sedation depth do not fully explain drive heterogeneity. This study evaluated the relationship of systemic inflammation and vascular permeability markers with respiratory drive and clinical outcomes in ARDS.

METHODS

ARDS patients enrolled in the multicenter EPVent-2 trial with requisite data and plasma biomarkers were included. Neuromuscular blockade recipients were excluded. Respiratory drive was measured as PES0.1, the change in esophageal pressure during the first 0.1 s of inspiratory effort. Plasma angiopoietin-2, interleukin-6, and interleukin-8 were measured concomitantly, and 60-day clinical outcomes evaluated.

RESULTS

54.8% of 124 included patients had detectable respiratory drive (PES0.1 range of 0-5.1 cm H2O). Angiopoietin-2 and interleukin-8, but not interleukin-6, were associated with respiratory drive independently of acid-base, oxygenation, respiratory mechanics, and sedation depth. Sedation depth was not significantly associated with PES0.1 in an unadjusted model, or after adjusting for mechanics and chemoreceptor input. However, upon adding angiopoietin-2, interleukin-6, or interleukin-8 to models, lighter sedation was significantly associated with higher PES0.1. Risk of death was less with moderate drive (PES0.1 of 0.5-2.9 cm H2O) compared to either lower drive (hazard ratio 1.58, 95% CI 0.82-3.05) or higher drive (2.63, 95% CI 1.21-5.70) (p = 0.049).

CONCLUSIONS

Among patients with ARDS, systemic inflammatory and vascular permeability markers were independently associated with higher respiratory drive. The heterogeneous response of respiratory drive to varying sedation depth may be explained in part by differences in inflammation and vascular permeability.

Latent Class Analysis Reveals COVID-19-related Acute Respiratory Distress Syndrome Subgroups with Differential Responses to Corticosteroids

Rationale

Two distinct subphenotypes have been identified in acute respiratory distress syndrome (ARDS), but the presence of subgroups in ARDS associated with coronavirus disease (COVID-19) is unknown.

Objectives

To identify clinically relevant, novel subgroups in COVID-19–related ARDS and compare them with previously described ARDS subphenotypes.

Methods

Eligible participants were adults with COVID-19 and ARDS at Columbia University Irving Medical Center. Latent class analysis was used to identify subgroups with baseline clinical, respiratory, and laboratory data serving as partitioning variables. A previously developed machine learning model was used to classify patients as the hypoinflammatory and hyperinflammatory subphenotypes. Baseline characteristics and clinical outcomes were compared between subgroups. Heterogeneity of treatment effect for corticosteroid use in subgroups was tested.

Measurements and Main Results

From March 2, 2020, to April 30, 2020, 483 patients with COVID-19–related ARDS met study criteria. A two-class latent class analysis model best fit the population (P = 0.0075). Class 2 (23%) had higher proinflammatory markers, troponin, creatinine, and lactate, lower bicarbonate, and lower blood pressure than class 1 (77%). Ninety-day mortality was higher in class 2 versus class 1 (75% vs. 48%; P < 0.0001). Considerable overlap was observed between these subgroups and ARDS subphenotypes. Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) RT-PCR cycle threshold was associated with mortality in the hypoinflammatory but not the hyperinflammatory phenotype. Heterogeneity of treatment effect to corticosteroids was observed (P = 0.0295), with improved mortality in the hyperinflammatory phenotype and worse mortality in the hypoinflammatory phenotype, with the caveat that corticosteroid treatment was not randomized.

Conclusions

We identified two COVID-19–related ARDS subgroups with differential outcomes, similar to previously described ARDS subphenotypes. SARS-CoV-2 PCR cycle threshold had differential value for predicting mortality in the subphenotypes. The subphenotypes had differential treatment responses to corticosteroids.

Continuing Non-Invasive Ventilation During Amyotrophic Lateral Sclerosis-Related Hospice Care Is Medically, Administratively, and Financially Feasible

BACKGROUND

Amyotrophic Lateral Sclerosis (ALS) is a terminal neuromuscular disease with patients dying within 3-5 years of diagnosis. Most patients choose to forego invasive life sustaining measures. Timing of hospice referral can be challenging given the advancement of non-invasive ventilation (NIV) technology.

OBJECTIVE

To describe the characteristics of patients enrolled in hospice from an ALS clinic at 1 academic medical center and to perform a cost analysis for patients who remained on ventilator support.

METHODS

Retrospective cross-sectional study of patients enrolled in hospice over a 2-year period. Clinical characteristics included ALS Functional Rating Scale Revised (ALSFRS-R) score, Forced Vital Capacity (FVC), use of NIV and mechanical insufflation-exsufflation (MIE), riluzole use, and length of stay in hospice. A cost analysis was performed for patients enrolled in Duke Home Care and Hospice.

RESULTS

85 of 104 patients who died were enrolled in hospice. Median days enrolled in hospice was 84. Patients who continued on NIV had similar hospice length of stay as those on no respiratory support (88 versus 80 days, p = 0.83). Bulbar patients had a trend toward shorter length of stay in hospice than limb onset patients (71 versus 101 days, p = 0.49). Cost analysis showed that hospice maintained a mean net operating revenue of $3234.50 per patient who continued on NIV.

CONCLUSIONS

Hospice referrals for ALS patients on NIV can be challenging. This study shows that even with continued NIV use, most ALS patients die within the expected 6 months on home hospice, and care remains cost effective for hospice agencies.

Respiratory Failure in Amyotrophic Lateral Sclerosis

Amyotrophic lateral sclerosis is a progressive neuromuscular disease characterized by both lower motor neuron and upper motor neuron dysfunction. Although clinical presentations can vary, there is no cure for ALS, and the disease is universally terminal, with most patients dying of respiratory complications. Patients die, on average, within 3 to 5 years of diagnosis, unless they choose to undergo tracheostomy, in which case, they may live, on average, 2 additional years. Up to 95% of patients with ALS in the United States choose not to undergo tracheostomy; management of respiratory failure is therefore aimed at both prolonging survival as well as improving quality of life. Standard of care for patients with ALS includes treatment from multidisciplinary teams, but many patients do not have consistent access to a pulmonary physician who regularly sees patients with this disease. The goal of this review was to serve as an overview of respiratory considerations in the management of ALS. This article discusses noninvasive ventilation in the management of respiratory muscle weakness, mechanical insufflation/exsufflation devices for airway clearance, and treatment of aspiration, including timing of placement of a percutaneous endoscopic gastrostomy tube, as well as secretion management. In addition, it is important for physicians to consider end-of-life issues such as advanced directives, hospice referral, and ventilator withdrawal.

Effect of piroxicam on the nephrotoxicity induced by ochratoxin A in rats

Ochratoxin A (OTA) is a mycotoxin which contaminates animal feed and human food and is nephrotoxic for all animal species studied so far. It binds to plasma proteins and is transported into target organs, especially the kidney. An attempt to prevent its toxic effects has been made using piroxicam, a non-steroidal anti-inflammatory drug (NSAID). Piroxicam also binds strongly to plasma proteins and our hypothesis is that this drug could stop OTA-binding and transport into target organs, thereby preventing its nephrotoxicity. Our experiments on rats given OTA (289 micrograms/kg/48 h for 2 weeks) show that piroxicam prevents the enzymuria induced by OTA and increases renal elimination of OTA. In vivo, piroxicam could prove useful in preventing the chronic effects of ochratoxin A, mainly nephrotoxicity, at doses 5 mg/kg/48 h, which were not found to be nephrotoxic in experimental animals.