Update in Critical Care 2015

Long-Term Outcome after Prolonged Mechanical Ventilation. A Long-Term Acute-Care Hospital Study

Rationale: Patients managed at a long-term acute-care hospital (LTACH) for weaning from prolonged mechanical ventilation are at risk for profound muscle weakness and disability. Objectives: To investigate effects of prolonged ventilation on survival, muscle function, and its impact on quality of life at 6 and 12 months after LTACH discharge. Methods: This was a prospective, longitudinal study conducted in 315 patients being weaned from prolonged ventilation at an LTACH. Measurements and Main Results: At discharge, 53.7% of patients were detached from the ventilator and 1-year survival was 66.9%. On enrollment, maximum inspiratory pressure (Pi_max) was 41.3 (95% confidence interval, 39.4-43.2) cm H₂O (53.1% predicted), whereas handgrip strength was 16.4 (95% confidence interval, 14.4-18.7) kPa (21.5% predicted). At discharge, Pi_max did not change, whereas handgrip strength increased by 34.8% (P < 0.001). Between discharge and 6 months, handgrip strength increased 6.2 times more than did Pi_max. Between discharge and 6 months, Katz activities-of-daily-living summary score improved by 64.4%; improvement in Katz summary score was related to improvement in handgrip strength (r = -0.51; P < 0.001). By 12 months, physical summary score and mental summary score of 36-item Short-Form Survey returned to preillness values. When asked, 84.7% of survivors indicated willingness to undergo mechanical ventilation again. Conclusions: Among patients receiving prolonged mechanical ventilation at an LTACH, 53.7% were detached from the ventilator at discharge and 1-year survival was 66.9%. Respiratory strength was well maintained, whereas peripheral strength was severely impaired throughout hospitalization. Six months after discharge, improvement in muscle function enabled patients to perform daily activities, and 84.7% indicated willingness to undergo mechanical ventilation again.

Interleukin-34 Ameliorates Survival and Bacterial Clearance in Polymicrobial Sepsis

OBJECTIVES

Sepsis is a devastating condition with a high mortality rate and limited treatments. Sepsis is characterized by a failed host immune response to contain the infection, resulting in organ dysfunction. Interleukin-34 is new cytokine involved in infection and immunity. Whether interleukin-34 is beneficial or deleterious to sepsis and the underlying mechanisms remains unknown.

DESIGN

Prospective randomized animal investigation and in vitro studies.

SETTING

Research laboratory at a university hospital.

SUBJECTS

Wild-type C57BL/6 mice were used for in vivo studies, and septic human patients and healthy human subjects were used to obtain blood for in vitro studies.

INTERVENTIONS

Interleukin-34 concentrations were measured in human sepsis patients and healthy individuals. The effects of interleukin-34 administration on survival, bacterial burden, organ injury, and inflammatory response were assessed in a murine model of cecal ligation and puncture-induced polymicrobial sepsis.

MEASUREMENTS AND MAIN RESULTS

Interleukin-34 levels were significantly elevated in human sepsis and cecal ligation and puncture-induced experimental sepsis. Interleukin-34 administration improved survival and bacterial clearance, although suppressed vascular leakage and organ injury after cecal ligation and puncture-induced polymicrobial sepsis. Neutralization of interleukin-34 increased mortality rate and decreased bacterial clearance in septic mice. An increased neutrophil and macrophage influx were developed in interleukin-34-treated mice at the site of infection, accompanied by elevated production of neutrophil chemokine chemokine (C-X-C motif) ligand 1 and macrophage chemokine C-C motif chemokine ligand 2 in the peritoneal cavity. Depletion of neutrophils or macrophages reversed interleukin-34-mediated protection against polymicrobial sepsis.

CONCLUSIONS

We reported for the first time a potential therapeutic role for interleukin-34 in sepsis and suggested that interleukin-34 is a novel target for the development of therapeutic agents against sepsis.

Dexmedetomidine Impairs Diaphragm Function and Increases Oxidative Stress but Does Not Aggravate Diaphragmatic Atrophy in Mechanically Ventilated Rats

BACKGROUND

Anesthetics in ventilated patients are critical as any cofactor hampering diaphragmatic function may have a negative impact on the weaning progress and therefore on patients' mortality. Dexmedetomidine may display antioxidant and antiproteolytic properties, but it also reduced glucose uptake by the muscle, which may impair diaphragm force production. This study tested the hypothesis that dexmedetomidine could inhibit ventilator-induced diaphragmatic dysfunction.

METHODS

Twenty-four rats were separated into three groups (n = 8/group). Two groups were mechanically ventilated during either dexmedetomidine or pentobarbital exposure for 24 h, referred to as interventional groups. A third group of directly euthanized rats served as control. Force generation, fiber dimensions, proteolysis markers, protein oxidation and lipid peroxidation, calcium homeostasis markers, and glucose transporter-4 (Glut-4) translocation were measured in the diaphragm.

RESULTS

Diaphragm force, corrected for cross-sectional area, was significantly decreased in both interventional groups compared to controls and was significantly lower with dexmedetomidine compared to pentobarbital (e.g., 100 Hz: -18%, P < 0.0001). In contrast to pentobarbital, dexmedetomidine did not lead to diaphragmatic atrophy, but it induced more protein oxidation (200% vs. 73% in pentobarbital, P = 0.0015), induced less upregulation of muscle atrophy F-box (149% vs. 374% in pentobarbital, P < 0.001) and impaired Glut-4 translocation (-73%, P < 0.0005). It activated autophagy, the calcium-dependent proteases, and caused lipid peroxidation similarly to pentobarbital.

CONCLUSIONS

Twenty-four hours of mechanical ventilation during dexmedetomidine sedation led to a worsening of ventilation-induced diaphragm dysfunction, possibly through impaired Glut-4 translocation. Although dexmedetomidine prevented diaphragmatic fiber atrophy, it did not inhibit oxidative stress and activation of the proteolytic pathways.

European Respiratory Society International Congress 2018: Allied Respiratory Professionals' report of highlighted sessions

This article provides an overview of outstanding sessions that were supported by Assembly 9 during the recent European Respiratory Society International Congress in Paris, France. Session content was mainly targeted at allied health professionals such as respiratory physiologists, respiratory physiotherapists and respiratory nurses. Recent developments and novel findings related to pulmonary function testing, respiratory muscle function assessments and treatment, and multidimensional and multidisciplinary approaches to the assessment and management of dyspnoea were the focus of these sessions and are summarised here.

Antihistone Properties of C1 Esterase Inhibitor Protect against Lung Injury

RATIONALE

Acute respiratory distress syndrome is characterized by alveolar epithelial cell injury, edema formation, and intraalveolar contact phase activation.

OBJECTIVES

To explore whether C1 esterase inhibitor (C1INH), an endogenous inhibitor of the contact phase, may protect from lung injury in vivo and to decipher the possible underlying mechanisms mediating protection.

METHODS

The ability of C1INH to control the inflammatory processes was studied in vitro and in vivo.

MEASUREMENTS AND MAIN RESULTS

Here, we demonstrate that application of C1INH alleviates bleomycin-induced lung injury via direct interaction with extracellular histones. In vitro, C1INH was found to bind all histone types. Interaction with histones was independent of its protease inhibitory activity, as demonstrated by the use of reactive-center-cleaved C1INH, but dependent on its glycosylation status. C1INH sialylated-N- and -O-glycans were not only essential for its interaction with histones but also to protect against histone-induced cell death. In vivo, histone-C1INH complexes were detected in bronchoalveolar lavage fluid from patients with acute respiratory distress syndrome and multiple models of lung injury. Furthermore, reactive-center-cleaved C1INH attenuated pulmonary damage evoked by intravenous histone instillation.

CONCLUSIONS

Collectively, C1INH administration provides a new therapeutic option for disorders associated with histone release.