Factors Affecting Surfactant Responsiveness: Influence of mode of administration and ventilation, disease stage and type of surfactant

Historically, Kurt von Neergaard was the first to suggest that surface tension plays an important role in lung elasticity. He showed, in 1929, that the pressure necessary for fIlling the lung with liquid was less than half the pressure necessary for filling the lung WiOl air, and concluded that two-thirds to three-fourths of the elasticity of the lung was derived from interfacial forces. The problem with his discovery was that this paper was published in Gemlan and that, for 25 years, no scientists in the evolving fIeld really took note of this pnblication. In 1954, Macklin described the presence of a thin aqueous mucoid microfIlm, formed from secretion of the granular pneumocytes, on the pnlmonary alveolar walls and which is in constant slow movement toward the phagocytic pneumocytes and bronchioles. One year later, Pattie noticed the remarkable stability of foam and bubbles from lung edema and healthy lung cut. He assumed that the walls of these bubbles consists of surface-active material which must lower the surface tension to nearly zero. In 1957, Clements [was the fIrst to prove the direct evidence of surface active material in the lungs. He measured surface tension of a surface fIlm derived from the lung by using a Wilhelmy balance and demonstrated that the surface tension was not a constant value; when the surface was stretched the tension was relatively high (40 dynes/cm), but when the surface area was decreased the tension fell to 10 dynes/cm. He pointed out that such a reduction in surface tension during deflation in the lung would tend to stabilize the air spaces by permitting them to remain open at low lung volumes. Two years later, Avery and Mead demonstrated that lung extracts of very small premature infants and infants dying with hyaline membrane disease had much higher surface tension than normal lung extracts, due to

Gram-negative antibiotic resistance: there is a price to pay

Resistance rates are increasing among several problematic Gram-negative pathogens that are often responsible for serious nosocomial infections, including Acinetobacter spp., Pseudomonas aeruginosa, and (because of their production of extended-spectrum β-lactamase) Enterobacteriaceae. The presence of multiresistant strains of these organisms has been associated with prolonged hospital stays, higher health care costs, and increased mortality, particularly when initial antibiotic therapy does not provide coverage of the causative pathogen. Conversely, with high rates of appropriate initial antibiotic therapy, infections caused by multiresistant Gram-negative pathogens do not negatively influence patient outcomes or costs. Taken together, these observations underscore the importance of a 'hit hard and hit fast' approach to treating serious nosocomial infections, particularly when it is suspected that multiresistant pathogens are responsible. They also point to the need for a multidisciplinary effort to combat resistance, which should include improved antimicrobial stewardship, increased resources for infection control, and development of new antimicrobial agents with activity against multiresistant Gram-negative pathogens

Electrical impedance tomography and trans-pulmonary pressure measurements in a patient with extreme respiratory drive

Preserving spontaneous breathing during mechanical ventilation prevents muscle atrophy of the diaphragm, but may lead to ventilator induced lung injury (VILI). We present a case in which monitoring of trans-pulmonary pressure and ventilation distribution using Electrical Impedance Tomography (EIT) provided essential information for preventing VILI

Recruitment Maneuvers and Higher PEEP, the So-Called Open Lung Concept, in Patients with ARDS

This article is one of ten reviews selected from the Annual Update in Intensive Care and Emergency Medicine 2019. Other selected articles can be found online at https://www.biomedcentral.com/collections/annualupdate2019. Further information about the Annual Update in Intensive Care and Emergency Medicine is available from http://www.springer.com/series/8901

Detection of 'best' positive end-expiratory pressure derived from electrical impedance tomography parameters during a decremental positive end-expiratory pressure trial

Introduction: This study compares different parameters derived from electrical impedance tomography (EIT) data to define 'best' positive end-expiratory pressure (PEEP) during a decremental PEEP trial in mechanically-ventilated patients. 'Best' PEEP is regarded as minimal lung collapse and overdistention in order to prevent ventilator-induced lung injury.Methods: A decremental PEEP trial (from 15 to 0 cm H2O PEEP in 4 steps) was performed in 12 post-cardiac surgery patients on the ICU. At each PEEP step, EIT measurements were performed and from this data the following were calculated: tidal impedance variation (TIV), regional compliance, ventilation surface area (VSA), center of ventilation (COV), regional ventilation delay (RVD index), global inhomogeneity (GI index), and intratidal gas distribution. From the latter parameter we developed the ITV index as a new homogeneity parameter. The EIT parameters were compared with dynamic compliance and the PaO2/FiO2 ratio.Results: Dynamic compliance and the PaO2/FiO2 ratio had the highest value at 10 and 15 cm H2O PEEP, respectively. TIV, regional compliance and VSA had a maximum value at 5 cm H2O PEEP for the non-dependent lung region and a maximal value at 15 cm H2O PEEP for the dependent lung regio

In vivo evaluation of the inhibitory capacity of human plasma on exogenous surfactant function

Objective: The adult respiratory distress syndrome (ARDS) and neonatal respiratory distress syndrome (RDS) are characterized by high permeability pulmonary edema which contains plasma-derived proteins inhibiting pulmonary surfactant function. Currently, discussion continues as to what dose of surfactant is required for treatment of these syndromes. Design: The purpose of this study was to investigate the amount of exogenous surfactant needed to overcome the inhibitory components in human plasma. Male adult rats suffering from respiratory failure due to surfactant depletion after whole-lung lavage received human plasma (4 ml/kg body weight) mixed with surfactant at different concentrations, intratracheally. Rats receiving surf

Lung stress and strain calculations in mechanically ventilated patients in the intensive care unit

Background Stress and strain are parameters to describe respiratory mechanics during mechanical ventilation. Calculations of stress require invasive and difficult to perform esophageal pressure measurements. The hypothesis of the present study was: Can lung stress be reliably calculated based on non-invasive lung volume measurements, during a decremental Positive end-expiratory pressure (PEEP) trial in mechanically ventilated patients with different diseases? Methods Data of 26 pressure-controlled ventila

Partial neuromuscular blockage to promote weaning from mechanical ventilation in severe ARDS: A case report

Spontaneous breathing efforts during mechanical ventilation can lead to patient self-inflicted lung injury (P-SILI). In order to prevent P-SILI, patients are generally heavily sedated and receive muscle relaxation, resulting in a slower weaning process. We present a case in which we applied partial neuromuscular blockage in order to prevent P-SILI while allowing spontaneous breathing but with limited efforts during assist mechanical ventilation