Setting an Agenda: Results of a Consensus Process on Research Directions in Distance Simulation.

Background: The COVID-19 pandemic forced rapid implementation and refinement of distance simulation methodologies in which participants and/or facilitators are not physically colocated. A review of the distance simulation literature showed that heterogeneity in many areas (including nomenclature, methodology, and outcomes) limited the ability to identify best practice. In April 2020, the Healthcare Distance Simulation Collaboration was formed with the goal of addressing these issues.

Impact of the Right Ventricular Sokolow-Lyon Index in Children with Idiopathic Pulmonary Arterial Hypertension.

Right ventricular (RV) hypertrophy is regarded as the adaptation on chronic RV pressure load in pulmonary hypertension. As the RV Sokolow-Lyon index (RVSLI) is an electrocardiographic marker of RV hypertrophy, we hypothesized that RVSLI might be able to reflect RV pressure load. Therefore, the purpose of this study was to characterize the diagnostic impact of the RVSLI in children with idiopathic pulmonary arterial hypertension (IPAH) in order to assess disease severity and to evaluate its value for the prediction of worse outcome.

Reaction rates of oxygen with hemoglobin measured by non-equilibrium facilitated oxygen diffusion through hemoglobin solutions.

The purpose of this study was to verify the concept of non-equilibrium facilitated oxygen diffusion. This work succeeds our previous study, where facilitated oxygen diffusion by hemoglobin was measured at conditions of chemical equilibrium, and which yielded diffusion coefficients of hemoglobin and of oxygen. In the present work chemical non-equilibrium was induced using very thin diffusion layers.

Diffusion coefficients of oxygen and hemoglobin measured by facilitated oxygen diffusion through hemoglobin solutions.

Diffusion coefficients of oxygen (DO2) and hemoglobin (DHb) were obtained from measuring the oxygen flux through thin layers of hemoglobin solutions at 20 degrees C. The liquid layers were supported by a membrane and not soaked in any filter material. Oxygen fluxes were measured from the changes in oxygen partial pressure in the gas phases at both sides of the layer.

Nematic polymer liquid-crystal wave plate for high-power lasers at 1054 nm.

A nematic polymer liquid crystal is used to construct wave plates for use at 1054 nm. Three methods of wave-plate construction are discussed: double substrate with fiber spacers in homogeneous distribution, double substrate with fiber spacers in annular distribution, and single substrate. The polymer liquid crystal shows high laser-damage resistance, making it particularly useful for high-peak-power laser applications.

Effect of metabolic acidosis on pulmonary gas exchange of artificially ventilated dogs.

It is well established that metabolic acidosis induces a reduction in alveolar-arterial O2 difference [(A-a)Do2] in artificially ventilated dogs by shifting the oxyhemoglobin dissociation curve (ODC) and/or by improving the distribution of the ventilation-to-perfusion ratio (VA/Q) throughout the lung. To assess the influence of these two factors we examined eight artificially ventilated dogs before and after induction of metabolic acidosis by a perfusion of 0.3 mol HCl.

Reestimation of the effects of inorganic phosphates on the equilibrium between oxygen and hemoglobin.

In a previous paper, published in this journal, we showed that the data obtained in patients with severe ketoacidosis suggest that inorganic phosphates (K2HPO4) can increase their P50 and therefore enhance tissue oxygenation without concomitant alteration of the 2,3 diphosphoglycerate (DPG). In order to test the hypothesis that K2HPO4 could influence the oxyhemoglobin dissociation curve (ODC) by a mecanism which was not DPG mediated we have measured the total ODC on whole blood with and without addition of 13-80 mmol/l of inorganic phosphates. On average, the level of DPG remained unchanged when the P50 with K2HPO4 was significantly higher (p greater than 0.

Effect of lung volume and positional changes on pulmonary diffusing capacity and its components.

Normal subjects have a larger diffusing capacity normalized per liter alveolar volume (DL/VA) in the supine than in the sitting position. Body position changes total lung diffusing capacity (DL), DL/VA, membrane conductance (Dm), and effective pulmonary capillary blood volume (Qc) as a function of alveolar volume (VA). These functions were studied in 37 healthy volunteers.

Computed myocardial PO2 histograms: effects of various geometrical and functional conditions.

A model of myocardial oxygenation was developed that allows calculation of Po2 histograms under varying conditions. The model consists of parallel tissue cylinders with varying radii, simulating the heterogeneity of capillary spacing, in agreement with our previous experimental results. The facilitated diffusion of O2 by myoglobin, an additional resistance to diffusion at the capillary level, and the Michaelis-Menten type of O2 consumption were also incorporated.

Early detection of shock in critically ill patients by skeletal muscle PO2 assessment.

The usefulness of skeletal muscle PO2 assessment in monitoring patients at risk of shock was evaluated in 20 critically ill patients. A shock score, inotropic score, and combined inotropic-shock score were calculated. If the median skeletal muscle PO2 assessment was more than 31.

Muscle oxygen tension, hemodynamics, and oxygen transport after extracorporeal circulation.

In eight patients who underwent elective coronary bypass operation, skeletal muscle PO2 was measured with a polarographic needle electrode as an index of peripheral tissue perfusion to study recovery after extracorporeal circulation. Measurements of skeletal muscle PO2 and O2 supply to the tissues were obtained immediately after ICU admission and after 2, 4, 8, and 16 h. During the first 2 h, mean arterial BP was high, mixed venous PO2 decreased, the arteriovenous O2 difference increased, and skeletal muscle PO2 decreased.

Hypoxic ventilatory response of rats born at simulated altitude.

Steady-state ventilatory response to isocapnic hypoxia was measured in awake rats: a) resident at sea level (Control); b) born at sea level and acclimatized to a simulated altitude of 3500 m (Newcomers); c) born and raised for two generations at a simulated altitude of 3500 m (HA-II Generation). Arterial PO2, PCO2, and pH were measured at the same time as ventilation. Resting ventilation (mean +/- SE) on room air in Control, Newcomers, and HA-II Generation was 707 +/- 25, 811 +/- 28 and 878 +/- 21 ml.

Determination of permeabilities for two gases from recording the partial pressure of one gas.

When a flexible diffusion layer separates two closed gas chambers containing different mixtures of several gases, the different permeabilities of the layer for these gases lead to differences in the total gas pressures of the two chambers resulting in bulging of the layer and consequent changes in the chamber volumes. Application of the gas laws to binary gas mixtures provides two equations relating the partial pressure changes of one gas in any of the two chambers to the partial pressure difference between the two chambers across the layer. This permits the calculation of the two unknown factors, permeability (or Krogh's diffusion coefficient) of the layer for the measured gas and the permeability ratio of the two gases.

Regulation of the peripheral vasculature and tissue oxygenation in health and disease.

The evidence has become convincing that in certain critical illnesses such as ARDS, there is pathologic disturbance in O2 delivery to the tissues. This disturbance is marked by an abnormal dependency of O2 uptake upon total O2 delivery. Although this has been attributed to mitochondrial dysfunction in the past, current belief is that such apparent dysfunction is secondary to derangement of the microcirculation that causes an impairment in tissue oxygenation.

Facilitated carbon dioxide transport in bovine albumin solutions.

Steady-state CO2 diffusion in the presence of a CO2 gradient was measured in thin layers of bovine albumin solutions containing different amounts of buffer base, added as NaHCO3, and/or of NaCl. In the same solutions, electrical potentials due to the CO2 diffusion across the layers were measured. Addition of carbonic anhydrase induced a chemical reaction equilibrium to exist for the CO2 reaction system, and led to equilibrium values for facilitated CO2 transport due to a bicarbonate flux and to maximum values for the diffusion potential.