Paradoxical Positioning: Does "Head Up" Always Improve Mechanics and Lung Protection?

Objectives: Head-elevated body positioning, a default clinical practice, predictably increases end-expiratory transpulmonary pressure and aerated lung volume. In acute respiratory distress syndrome (ARDS), however, the net effect of such vertical inclination on tidal mechanics depends upon whether lung recruitment or overdistension predominates. We hypothesized that in moderate to severe ARDS, bed inclination toward vertical unloads the chest wall but adversely affects overall respiratory system compliance (C rs ).

Paradoxical response to chest wall loading predicts a favorable mechanical response to reduction in tidal volume or PEEP.

Background: Chest wall loading has been shown to paradoxically improve respiratory system compliance (C) in patients with moderate to severe acute respiratory distress syndrome (ARDS). The most likely, albeit unconfirmed, mechanism is relief of end-tidal overdistension in 'baby lungs' of low-capacity. The purpose of this study was to define how small changes of tidal volume (V) and positive end-expiratory pressure (PEEP) affect C (and its associated airway pressures) in patients with ARDS who demonstrate a paradoxical response to chest wall loading.

A Rationale for Safe Ventilation with Inhalation Injury: An Editorial Review.

Lung injury from smoke inhalation manifests as airway and parenchymal damage, at times leading to the acute respiratory distress syndrome. From the beginning of this millennium, the approach to mechanical ventilation in the patient with ARDS was based on reduction of tidal volume to 6 milliliters/kilogram of ideal body weight, maintaining a ceiling of plateau pressure, and titration of driving pressure (plateau pressure minus PEEP). Beyond these broad constraints, there is little specification for the mechanics of ventilator settings, consideration of the metabolic impact of the disease process on the patient, or interaction of patient disease and ventilator settings.

Static and Dynamic Measurements of Compliance and Driving Pressure: A Pilot Study.

Rationale: Monitoring tidal cycle mechanics is key to lung protection. For this purpose, compliance and driving pressure of the respiratory system are often measured clinically using the plateau pressure, obtained after imposing an extended end-inspiratory pause, which allows for relaxation of the respiratory system and redistribution of inflation volume (method A). Alternative methods for estimating compliance and driving pressure utilize the measured pressure at the earliest instance of zero flow (method B), the inspiratory slope of the pressure-time tracing during inflation with constant flow (method C), and the expiratory time constant (method D).

Intracycle power and ventilation mode as potential contributors to ventilator-induced lung injury.

Background: High rates of inflation energy delivery coupled with transpulmonary tidal pressures of sufficient magnitude may augment the risk of damage to vulnerable, stress-focused units within a mechanically heterogeneous lung. Apart from flow amplitude, the clinician-selected flow waveform, a relatively neglected dimension of inflation power, may distribute inflation energy of each inflation cycle non-uniformly among alveoli with different mechanical properties over the domains of time and space. In this initial step in modeling intracycle power distribution, our primary objective was to develop a mathematical model of global intracycle inflation power that uses clinician-measurable inputs to allow comparisons of instantaneous ICP profiles among the flow modes commonly encountered in clinical practice: constant, linearly decelerating, exponentially decelerating (pressure control), and spontaneous (sinusoidal).

Reliable Estimates of Power Delivery During Mechanical Ventilation Utilizing Easily Obtained Bedside Parameters.

Background: Ventilator-induced lung injury (VILI) requires repetitive transfer of energy from the ventilator to the compromised lung. To understand this phenomenon, 2 sets of equations have been developed to partition total inflation energy into harmless and hazardous components using an arbitrary level of alveolar pressure as a threshold beyond which further energy increments may become damaging. One set of equations uses premeasured resistance and compliance as inputs to predict the energy that would be delivered by typical ventilator settings, whereas the other equation set uses observed output values for end-inspiratory peak and plateau pressure of an already completed inflation.

Lethal hyperammonemia in a CAR-T cell recipient due to pneumonia: a case report of a unique severe complication.

We report the first incidence of infection causing lethal hyperammonemia in a chimeric receptor antigen T cell (CAR-T) recipient. A 53-year-old woman, after receiving CAR-T therapy, suffered sepsis and encephalopathy. She was found to have hyperammonemia up to 643 µmol/L.

Early (<4 Weeks) Versus Standard (≥ 4 Weeks) Endoscopically Centered Step-Up Interventions for Necrotizing Pancreatitis.

Objectives: Current guidelines for necrotizing pancreatitis (NP) recommend delay in drainage ± necrosectomy until 4 or more weeks after initial presentation to allow collections to wall off. However, evidence of infection with clinical deterioration despite maximum support may mandate earlier (<4 weeks) intervention. There are concerns, but scant data regarding risk of complications and outcomes with early endoscopic intervention.

The Rare Complication and Diagnostic Challenges of Pulmonary Eosinophilia in Graft versus Host Disease Patients after Hematopoietic Stem Cell Transplantation.

Purpose: Chronic graft versus host disease (cGvHD) is a common complication of hematopoietic stem cell transplantation (HSCT). Eosinophilic lung disease is a rare poorly understood complication in HSCT patients with cGvHD. These patients present similarly to those with Acute Eosinophilic Pneumonia (AEP).

Severe polyserositis induced by the 13-valent pneumococcal conjugate vaccine: a case report.

Background: The United States Advisory Committee on Immunization Practices recommends administration of the 13-valent pneumococcal conjugate vaccine in series with the 23-valent pneumococcal polysaccharide vaccine for prevention of pneumonia in the elderly. Reports of autoimmune or auto-inflammatory diseases as a result of pneumococcal vaccination, especially pneumococcal conjugate vaccine, are extremely rare.

Case Presentation: We present a case of severe serositis in a 75-year-old Caucasian woman complicated by pericardial and pleural effusions in the setting of recent 13-valent pneumococcal conjugate vaccine vaccination and no other obvious etiology.

Audible Coronary Artery Stenosis.

Objective: Hemodynamically significant coronary artery stenoses generate turbulent blood flow patterns that manifest as intracoronary murmurs. This study aims to evaluate the performance of modern acoustic detection of these murmurs by acoustic signals captured from patients undergoing gold standard comparative coronary angiography.

Methods: We prospectively studied 156 patients undergoing elective coronary angiography, excluding those with acute coronary syndrome, prior chest surgery, or significant valvular disease.

Noninvasive quantification of ascorbate and glutathione concentration in the elderly human brain.

In this study, ascorbate (Asc) and glutathione (GSH) concentrations were quantified noninvasively using double-edited (1)H MRS at 4 T in the occipital cortex of healthy young [age (mean ± standard deviation) = 20.4 ± 1.4 years] and elderly (age = 76.

Hexapeptide libraries for enhanced protein PTM identification and relative abundance profiling in whole human saliva.

Dynamic range compression (DRC) by hexapeptide libraries increases MS/MS-based identification of lower-abundance proteins in complex mixtures. However, two unanswered questions impede fully realizing DRC's potential in shotgun proteomics. First, does DRC enhance identification of post-translationally modified proteins? Second, can DRC be incorporated into a workflow enabling relative protein abundance profiling? We sought to answer both questions analyzing human whole saliva.