[Time gain by helicopter transportation of ST-elevation myocardial infarction patients]

Helicopter transportation of ST-elevation myocardial infarction patients have verified a reduction in the overall system delay, and should be considered in case of long transportation. The most suitable location of the helicopter base is in remote areas, close to the patients to be transferred. Helipads should be adjoining the percutaneous coronary intervention centre in order to allow direct transfer without the ambulance transfer. Helicopters that can operate both day and night and in poor visibility are recommended. Specially trained physicians, able to provide the required, advanced, in-flight treatment, should staff the helicopters.

Stereological assessment of mouse lung parenchyma via nondestructive, multiscale micro-CT imaging validated by light microscopic histology

Quantitative assessment of the lung microstructure using standard stereological methods such as volume fractions of tissue, alveolar surface area, or number of alveoli, are essential for understanding the state of normal and diseased lung. These measures are traditionally obtained from histological sections of the lung tissue, a process that ultimately destroys the three-dimensional (3-D) anatomy of the tissue. In comparison, a novel X-ray-based imaging method that allows nondestructive sectioning and imaging of fixed lungs at multiple resolutions can overcome this limitation. Scanning of the whole lung at high resolution and subsequent regional sampling at ultrahigh resolution without physically dissecting the organ allows the application of design-based stereology for assessment of the whole lung structure. Here we validate multiple stereological estimates performed on micro-computed tomography (μCT) images by comparing them with those obtained via conventional histology on the same mouse lungs. We explore and discuss the potentials and limitations of the two approaches. Histological examination offers higher resolution and the qualitative differentiation of tissues by staining, but ultimately loses 3-D tissue relationships, whereas μCT allows for the integration of morphometric data with the spatial complexity of lung structure. However, μCT has limited resolution satisfactory for the sterological estimates presented in this study but not for differentiation of tissues. We conclude that introducing stereological methods in μCT studies adds value by providing quantitative information on internal structures while not curtailing more complex approaches to the study of lung architecture in the context of physiological or pathological studies.

Dynamic needle tip positioning - ultrasound guidance for peripheral vascular access. A randomized, controlled and blinded study in phantoms performed by ultrasound novices

PURPOSE

The application of ultrasound-guidance for peripheral venous access is gaining popularity. It is possible to produce a short axis or a long axis sonographic view of the target vessel and apply an out-of-plane or in-plane needle tip approach. Our aim was to present the dynamic needle tip positioning technique and to estimate which approach is the most accurate for inserting the needle tip into the center of the target vessel.

MATERIALS AND METHODS

Fiftynine novices in ultrasound-guided peripheral vascular access participated. (A) a short axis view combined with an out-of-plane needle tip approach using dynamic needle tip positioning was compared to (B) a long axis view combined with an in-plane needle tip approach to a target vessel embedded in a gelatine phantom.

RESULTS

The success rate of method (A) was significantly higher than method (B) (97 % versus 81 %). The distance between the center of the target vessel and the final needle tip position was significantly shorter for method (A) compared to method (B).

CONCLUSION

The combined short axis and out-of-plane technique using dynamic needle tip positioning had a higher success rate and a shorter distance between the center of the target vessel and the needle tip compared to the combined long axis and in-plane technique.

Earlier reperfusion in patients with ST-elevation myocardial infarction by use of helicopter

Background

In patients with ST-elevation myocardial infarction (STEMI) reperfusion therapy should be initiated as soon as possible. This study evaluated whether use of a helicopter for transportation of patients is associated with earlier initiation of reperfusion therapy.

Material and methods

A prospective study was conducted, including patients with STEMI and symptom duration less than 12 hours, who had primary percutaneous coronary intervention (PPCI) performed at Aarhus University Hospital in Skejby. Patients with a health care system delay (time from emergency call to first coronary intervention) of more than 360 minutes were excluded. The study period ran from 1.1.2011 until 31.12.2011. A Western Denmark Helicopter Emergency Medical Service (HEMS) project was initiated 1.6.2011 for transportation of patients with time-critical illnesses, including STEMI.

Results

The study population comprised 398 patients, of whom 376 were transported by ambulance Emergency Medical Service (EMS) and 22 by HEMS. Field-triage directly to the PCI-center was used in 338 of patients. The median system delay was 94 minutes among those field-triaged, and 168 minutes among those initially admitted to a local hospital. Patients transported by EMS and field-triaged were stratified into four groups according to transport distance from the scene of event to the PCI-center: ≤25 km., 26–50 km., 51–75 km. and > 75 km. For these groups, the median system delay was 78, 89, 99, and 141 minutes. Among patients transported by HEMS and field-triaged the estimated median transport distance by ground transportation was 115 km, and the observed system delay was 107 minutes. Based on second order polynomial regression, it was estimated that patients with a transport distance of >60 km to the PCI-center may benefit from helicopter transportation, and that transportation by helicopter is associated with a system delay of less than 120 minutes even at a transport distance up to 150 km.

Conclusion

The present study indicates that use of a helicopter should be considered for field-triage of patients with STEMI to the PCI-center in case of long transportation. Such a strategy may ensure that patients living up to 150 km. from the PCI-center can be treated within 120 minutes of emergency call.

Imaging of the mouse lung with scanning laser optical tomography (SLOT)

The current study focuses on the use of scanning laser optical tomography (SLOT) in imaging of the mouse lung ex vivo. SLOT is a highly efficient fluorescence microscopy technique allowing rapid scanning of samples of a size of several millimeters, thus enabling volumetric visualization by using intrinsic contrast mechanisms of previously fixed lung lobes. Here, we demonstrate the imaging of airways, blood vessels, and parenchyma from whole, optically cleared mouse lung lobes with a resolution down to the level of single alveoli using absorption and autofluorescence scan modes. The internal structure of the lung can then be analyzed nondestructively and quantitatively in three-dimensional datasets in any preferred planar orientation. Moreover, the procedure preserves the microscopic structure of the lung and allows for subsequent correlative histologic studies. In summary, the current study has shown that SLOT is a valuable technique to study the internal structure of the mouse lung.

Cell-specific expression of human HGF by alveolar type II cells induces remodeling of septal wall tissue in the lung: a morphometric study

Hepatocyte growth factor (HGF) is involved in development and regeneration of the lungs. Human HGF, which was expressed specifically by alveolar epithelial type II cells after gene transfer, attenuated the bleomycin-induced pulmonary fibrosis in an animal model. As there are also regions that appear morphologically unaffected in fibrosis, the effects of this gene transfer to normal lungs is of interest. In vitro studies showed that HGF inhibits the formation of the basal lamina by cultured alveolar epithelial cells. Thus we hypothesized that, in the healthy lung, cell-specific expression of HGF induces a remodeling within septal walls. Electroporation of a plasmid of human HGF gene controlled by the surfactant protein C promoter was applied for targeted gene transfer. Using design-based stereology at light and electron microscopic level, structural alterations were analyzed and compared with a control group. HGF gene transfer increased the volume of distal air spaces, as well as the surface area of the alveolar epithelium. The volume of septal walls, as well as the number of alveoli, was unchanged. Volumes per lung of collagen and elastic fibers were unaltered, but a marked reduction of the volume of residual extracellular matrix (all components other than collagen and elastic fibers) and interstitial cells was found. A correlation between the volumes of residual extracellular matrix and distal air spaces, as well as total surface area of alveolar epithelium, could be established. Cell-specific expression of HGF leads to a remodeling of the connective tissue within the septal walls in the healthy lung, which is associated with more pronounced stretching of distal air spaces at a given hydrostatic pressure during instillation fixation.

Stereology and morphometry of lung tissue

This chapter deals with the stereological quantification of structural characteristics of the lung. The aim of design-based stereological methods is the unbiased and efficient estimation of structural features without making any assumptions on the underlying nature of the biological sample. The methods are based on rigorous sampling of location and orientation, the application of appropriate test systems, and the controlling of the precision of the estimates. Here, we describe the workflow from the fixation of the lung over the processing of the tissue samples to gaining estimates on the structural properties of the lung. Specifically, this chapter deals with methods for estimating the reference volume, sampling location, and sampling orientation, estimating volumes and surface areas of alveolar compartments, estimating total alveolar number, performing stereology at light and electron microscopic level, and dealing with technical problems such as tissue shrinkage. The procedures are illustrated using a worked example from the authors' own laboratory.

Long-term effects of intravenous iloprost in patients with idiopathic pulmonary arterial hypertension deteriorating on non-parenteral therapy

BACKGROUND

The majority of patients with idiopathic pulmonary arterial hypertension (IPAH) in functional classes II and III are currently being treated with non-parenteral therapies, including endothelin receptor antagonists (ERA), phosphodiesterase (PDE)-5 inhibitors, inhaled iloprost or combinations of these substances. If these treatments fail, current guidelines recommend the addition of parenteral prostanoid therapy. There is, however, limited evidence for the efficacy of parenteral prostanoids when added to combinations of non-parenteral therapies.

METHODS

In this retrospective, multicentre study we collected data from consecutive IPAH patients receiving intravenous iloprost in addition to optimized non-parenteral therapy between Jan 2002 and Dec 2009. Analyses included 6 min walk distance (6MWD), functional class, need for transplantation, and survival.

RESULTS

During the observation period, 50 patients were treated with intravenous iloprost in addition to non-parenteral therapy; 44% of the patients were on dual combination therapy and 52% on triple combination. Three months after initiation of iloprost, functional class had improved in 24% of the patients and the median 6MWD had increased from 289 m to 298 m (n.s.). During the observation period, 22 patients (44%) died and 14 (28%) underwent lung transplantation. The probabilities of LuTx-free survival at 1, 3 and 5 years following iloprost initiation were 38%, 17% and 17%, respectively. A 6MWD < 300 m and persistent functional class IV at 3 months after initiation of intravenous iloprost were predictors of an adverse outcome.

CONCLUSION

In essence, late initiation of intravenous iloprost in IPAH patients who previously failed to respond to non-parenteral therapies appears to be of limited efficacy in the majority patients. Alternative therapeutic options are currently not available, underlying the need for the development of new drugs.

The prognostic impact of follow-up assessments in patients with idiopathic pulmonary arterial hypertension

Current guidelines for the treatment of patients with idiopathic pulmonary arterial hypertension (IPAH) recommend basing therapeutic decision-making on haemodynamic, functional and biochemical variables. Most of these parameters have been evaluated as risk predictors at the time of diagnosis. The aim of the present study was to assess the prognostic impact of changes in these parameters after initiation of targeted therapy. A cohort of 109 patients with IPAH who had undergone haemodynamic, functional and biochemical assessments at baseline and 3-12 months after initiation of pulmonary arterial hypertension (PAH)-targeted therapy, were followed for a median 38 months in order to determine predictors of mortality at baseline and during the course of their disease. Within the observation period, 53 (48.6%) patients died and four (3.7%) underwent lung transplantation. Kaplan-Meier estimates for transplantation-free survival were 92%, 67%, and 51% at 1, 3, and 5 yrs, respectively. Among baseline variables, 6-min walk distance, right atrial pressure, cardiac index, mixed-venous oxygen saturation (S(v,O(2))) and N-terminal-pro brain natriuretic peptide (NT-proBNP) were independent predictors of survival. During follow-up, changes in World Health Organization functional class, cardiac index, S(v,O(2)) and NT-proBNP proved significant predictors of outcome. When assigned to prognostic groups, improvements as well as deteriorations in these parameters after initiation of PAH-targeted therapy had a strong impact on survival. Measurements obtained at follow-up had a higher predictive value than variables obtained at baseline. Changes in established predictors of outcome during the course of the disease provide important prognostic information in patients with IPAH.

Optimized murine lung preparation for detailed structural evaluation via micro-computed tomography

Utilizing micro-X-ray CT (μCT) imaging, we sought to generate an atlas of in vivo and intact/ex vivo lungs from normal murine strains. In vivo imaging allows visualization of parenchymal density and small airways (15-28 μm/voxel). Ex vivo imaging of the intact lung via μCT allows for improved understanding of the three-dimensional lung architecture at the alveolar level with voxel dimensions of 1-2 μm. μCT requires that air spaces remain air-filled to detect alveolar architecture while in vivo structural geometry of the lungs is maintained. To achieve these requirements, a fixation and imaging methodology that permits nondestructive whole lung ex vivo μCT imaging has been implemented and tested. After in vivo imaging, lungs from supine anesthetized C57Bl/6 mice, at 15, 20, and 25 cmH(2)O airway pressure, were fixed in situ via vascular perfusion using a two-stage flushing system while held at 20 cmH(2)O airway pressure. Extracted fixed lungs were air-dried. Whole lung volume was acquired at 1, 7, 21, and >70 days after the lungs were dried and served as validation for fixation stability. No significant shrinkage was observed: +8.95% change from in vivo to fixed lung (P = 0.12), -1.47% change from day 1 to day 7 (P = 0.07), -2.51% change from day 1 to day 21 (P = 0.05), and -4.90% change from day 1 to day 70 and thereafter (P = 0.04). μCT evaluation showed well-fixed alveoli and capillary beds correlating with histological analysis. A fixation and imaging method has been established for μCT imaging of the murine lung that allows for ex vivo morphometric analysis, representative of the in vivo lung.

Microscopy-based quantitative analysis of lung structure: application in diagnosis

INTRODUCTION

Stereology provides a set of methods that are appropriate for a microscopy-based quantitative assessment of lung structure. In general, the aim of stereology is to obtain information on three-dimensional structures from two-dimensional sections of these structures. The inherent impartiality of stereological principles is critical in order to meet the requirements of 'good laboratory practice'.

AREAS COVERED

This article is a systematic review of the applications of stereology to characterize pathological alterations of emphysema, fibrosis, acute lung injury and tumor grading. The reader is provided with a general overview of unbiased or design-based stereology and is provided with some examples of how these methods could be integrated into a diagnostic work-up of lung diseases in humans and animal models. The article also reviews the implications of a published statement, which defines standards for quantitative assessment of lung structure based on stereology, by the American Thoracic Society and the European Respiratory Society.

EXPERT OPINION

In view of the recently published standards for quantitative assessment of lung structure, unbiased stereological methods are strongly recommended, particularly as they provide valuable information in diagnosing lung diseases and allow a statistically valid quantitative comparison between different groups. Future developments will make the application of stereology in lung biology and pathology even more efficient. Moreover, there is also the potential for combing the principles of stereology with other imaging modalities (e.g., radiological), which will allow for non-invasive lung stereology.

Ultrastructural changes of the intracellular surfactant pool in a rat model of lung transplantation-related events

BACKGROUND

Ischemia/reperfusion (I/R) injury, involved in primary graft dysfunction following lung transplantation, leads to inactivation of intra-alveolar surfactant which facilitates injury of the blood-air barrier. The alveolar epithelial type II cells (AE2 cells) synthesize, store and secrete surfactant; thus, an intracellular surfactant pool stored in lamellar bodies (Lb) can be distinguished from the intra-alveolar surfactant pool. The aim of this study was to investigate ultrastructural alterations of the intracellular surfactant pool in a model, mimicking transplantation-related procedures including flush perfusion, cold ischemia and reperfusion combined with mechanical ventilation.

METHODS

Using design-based stereology at the light and electron microscopic level, number, surface area and mean volume of AE2 cells as well as number, size and total volume of Lb were determined in a group subjected to transplantation-related procedures including both I/R injury and mechanical ventilation (I/R group) and a control group.

RESULTS

After I/R injury, the mean number of Lb per AE2 cell was significantly reduced compared to the control group, accompanied by a significant increase in the luminal surface area per AE2 cell in the I/R group. This increase in the luminal surface area correlated with the decrease in surface area of Lb per AE2. The number-weighted mean volume of Lb in the I/R group showed a tendency to increase.

CONCLUSION

We suggest that in this animal model the reduction of the number of Lb per AE2 cell is most likely due to stimulated exocytosis of Lb into the alveolar space. The loss of Lb is partly compensated by an increased size of Lb thus maintaining total volume of Lb per AE2 cell and lung. This mechanism counteracts at least in part the inactivation of the intra-alveolar surfactant.