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The anesthetic conserving device (ACD) reduces consumption of volatile anesthetic drug by a conserving medium adsorbing exhaled drug during expiration and releasing it during inspiration. Elevated arterial CO2tension (PaCO2) has been observed in patients using the ACD, despite tidal volume increase to compensate for larger apparatus dead space. In a test lung using room temperature dry gas, this was shown to be due to adsorption of CO2in the ACD during expiration and release of CO2during the following inspiration. The effect in the test lung was higher than in patients. We tested the hypothesis that a lesser dead space effect in patients is due to higher temperature andor moisture attenuating rebreathing of CO2.

The objective of this investigation was to study regional absorption of inhaled insulin together with an enhancer (sodium di-octyl-sulfosuccinate [DOSS]) in the rabbit airways and lung. Insulin was administered with or without DOSS by aerosol inhalation, intratracheal infusion, intranasally, sublingually, and without DOSS intravenously. Blood glucose and plasma levels of insulin were measured during 100 min from the start of administration. Inhalation of insulin (3 U) with 0.25% or 1% DOSS decreased average blood glucose levels significantly more than inhalation of insulin (3 U) without DOSS. Intratracheal administration of 1.5 U of insulin with 0.25% DOSS in 0.3 mL of vehicle decreased the average blood glucose level significantly compared with intratracheal administration of 1.5 U of insulin and no DOSS in 0.3 mL of vehicle and compared with 1.5 U of insulin with 0.25% DOSS in 0.15 mL of vehicle. Intravenous insulin (1.5 U) and inhaled (1.5 U) insulin in 0.25% DOSS decreased average blood glucose levels significantly compared with intratracheal (0.15 mL), intranasal, and sublingual administration of 1.5 U of insulin with 0.25% DOSS. The bioavailability of inhaled insulin (1.5 U) with 0.25% DOSS was estimated to be 16% in comparison with 7% for intratracheally (0.15 mL), 1% intranasally, and 0.8% sublingually administered insulin (1.5 U with 0.25% DOSS), respectively. Inhaled insulin together with the absorption enhancer DOSS decreased the blood glucose level more effectively than insulin given intratracheally, intranasally, or sublingually. The effect on blood glucose reflected the difference in plasma insulin concentration for the different routes of administration.

Purpose. Small solutes which are deposited in the alveoli by aerosolinhalation will be absorbed across the alveolo-capillary barrier.Inhalation of dioctyl sodium sulfosuccinate (DOSS) enhances absorptionwhile having little or no effect on lung function, suggesting that surfaceactive agents may be used as enhancers of alveolar absorption ofinhaled pharmaceuticals. The purpose of this study was to examinethe effects of a selection of different surface active agents onalveolar absorption. Methods. The absorption of 99mTc-diethylene triamine pentaacetate(99mTc-DTPA) from the lungs was studied in rabbits. We studied fivedifferent surface active agents: DOSS, sodium glycodioxycholate(GDCA), sodium lauryl sulphate (NaLS), lysophosphatidyl choline(LPC) and polyoxyethylene-23-laurylether (P23LE). Results. DOSS and GDCA both dramatically enhanced the absorptionof 99mTc-DTPA. There was a moderate effect of NaLS, no significanteffect of LPC and P23LE reduced the rate of absorption. None of thecompounds affected gas exchange or lung compliance. Conclusions. There is a wide spectrum of effects of inhaled surfaceactive agents on the alveolar absorption of 99mTc-DTPA. Ioniccompounds such as DOSS and GDCA have the greatest effect, and furtherstudies of these classes of surface active agents for use as enhancersof alveolar absorption of pharmaceuticals seem warranted.

Pulmonary embolism (PE) leads to an abnormal alveolar deadspace that is expired in synchrony with gas from normally perfused alveoli. This feature of PE separates it from pulmonary diseases affecting the airways, which are characterized by nonsynchronous emptying of compartments with an uneven ventilation/perfusion relationship. An analysis of the single breath test (SBT) for CO2, SBT-CO2, focusing on the late tidal expirate, was made in order to evaluate the feasibility to use the SBT-CO2for the diagnosis of PE. The test was evaluated in 38 patients with suspected PE where pulmonary angiography showed that nine had PE and 29 did not. It was also tested in a reference population consisting of patients with normal lung function, obstructive lung disease and interstitial lung disease. Previously suggested gas exchange measurements for the diagnosis of PE, ie, the physiologic deadspace fraction, VDphys/VT, and the arterial-to-end-tidal CO2gradient, P(a-E')CO2, were also evaluated in the groups. SBT-CO, achieved a nearly complete separation between the patients with PE and those without. The other measurements, however, showed a substantial overlap between patients with PE and those with obstructive or interstitial lung disease. The SBT-CO2is simple and potentially widely available and warrants further study as a routine technique for the diagnosis of PE. (Chest 1989; 96:357–62)

The composition of gases and the gas tension in middle ear effusion in patients with serous otitis media have been investigated. By using a specially designed micro-method, very small amounts of middle ear fluid could be analyzed. The effusion was obtained by puncturing the air cells of the mastoid process. The average value of Po2was 41 mm Hg; Pco2was 58 mm Hg, pH 7.24. The possible mechanism for the impaired perfusion of the mucous membranes is discussed as well as some clinical consequences.

Continuous positive airways pressure (CPAP) has been applied with a face-chamber in 74 infants with hyaline membrane disease (HMD) before 10 h of age. The total survival rate was 91% and the complication rate of pneumothorax was low (5%). The incidence of long term developmental and neurological sequelae was also low (4%). Among the 19 surviving very low birth-weight (VLBW) infants below 1501 g, only one has shown neurological sequelae at follow-up examinations after 18 months to 3 years of age. The incidence of cerebellar hemorrhage was not higher in infants treated with the CPAP face chamber than in infants not receiving assisted ventilation. Bronchopulmonary dysplasia did not occur in any infant treated with CPAP face chamber only. The main advantages with the face chamber technique are: no disturbance of glottis function, no mucosal damage and tube obstruction, or sudden pressure drops, as seen with other modes of CPAP application. The face chamber technique is suitable for early application of CPAP in infants with HMD as it is efficient, without hazards, and easily applied.

Objective. To evaluate and further develop a method for determination and mathematical characterisation of the elastic pressure-volume (Pel-V) relationship in mechanically ventilated human subjects during one single modified insufflation with simultaneous determination of resistance of the respiratory system. Subjects. Eight adult non-smoking human subjects without heart, lung, or thoracic cage disease scheduled for non-thoracic surgery. The study was performed in anaesthetised and muscle-relaxed subjects. Measurements and Main Results. The Pel-V curve was determined with a computer-controlled Servo Ventilator 900C during a modified insufflation with either constant or sinusoidally varying flow. Pressure and flow were measured with the built-in sensors of the ventilator. Tracheal pressure (Ptr) was calculated by subtracting the pressure drop over the tracheal tube. The elastic recoil pressure in the peripheral lung, Pel, was obtained from the calculated Ptr by subtracting the pressure drop over the airways. Ptr was also directly measured through a catheter. The calculated Ptr gave similar results as the directly measured Ptr, thus indicating the reliability of the signal originating from the ventilator sensor for computation of downstream pressures. The inflection points of the sigmoidal Pel-V curve and the compliance of the linear segment were determined with high reproducibility. Conclusions. Using one single modified insufflation allows a fast and accurate determination of respiratory mechanics. The Pel-V curves were determined with high reproducibility and were adequately described by a three-segment model of the curve incorporating a linear segment between two asymmetrical non-linear segments.

To clarify how lung function at exercise is affected in sarcoidosis, and to analyze how exercise studies compare to esting measurements, 63 patients with pulmonary sarcoidosis were examined with lung mechanics and arterial blood gases during exercise. These findings were compared with simultaneously obtained, but previously reported results of the static lung pressure/volume curve and the lung resistance/static lung pressure curve. While mechanical variables at maximal exercise were as sensitive as those determined by measuring the PstL/V and RL/PstL curves, mechanics during spontaneous breathing at rest was less sensitive. The derangement of mechanics was more evident than that of arterial blood gases. No measurement at rest was a good predictor of working capacity or of arterial PaOs. A comprehensive exercise examination may be an alternative to resting investigations, which are either more elaborate or less sensitive. (Chest 1991; 99:572–78)

CERN's ISOLDE, an acronym for Isotope Separator On Line, went into operation again last year, after a major upgrading that has placed the facility in new building complex fed by a 1 GeV proton beam from the injector synchrotron, called the PS Booster (PSB). Hence, ISOLDE is now firmly integrated into the accelerator architecture of CERN. In the following, we give a description of the new installation and the physics that is being studied there. As is more often than not the case with laboratory visits and "portraits," the picture is kaleidoscopic, and we have tried to make the overview easier by placing most of the examples and all the detailed information in the form of "Panels," most of them illustrated and all of them, we hope, sufficiently self contained, so that they can be read without referring to the main text and to other Panels. For a start we point to Panel I, which gives some important dates and data concerning ISOLDE.

Background:Carbon dioxide elimination ( V˙co2) at steady state corresponds to the metabolic rate. A change in tidal ventilation will lead to a transient response in V˙o2if other determinants of V˙o2are constant. This principle may be applied in the critical care unit to reset ventilators.

Abstract: The relationship between the arterial blood pressure and the volume of the arteries within a segment of an extremity is nonlinear. The present paper shows how the flow and volume pulsations of the arteries within a limb segment can be simulated taking this property into account. An electrical model was constructed comprising one resistor and two voltage dependent ‘capacitors’, the latter corresponding to the pressure dependent elasticity, or compliance, of the arteries. Adequate simulations were obtained over a wide pressure range, which is impossible with linear models. The nonlinear, i.e. pressure dependent, relationship between the volume and pressure of arteries, observed under static conditions, must also be taken into consideration when studying pulsatile events with models whether mathematical or physical.

The rate of clearance from the lungs of inhaled technetium-99m labelled diethylene triamine penta-acetic acid (99mTc-DTPA) is often increased in interstitial lung disease as well as in smoking. In smokers a bi-exponential clearance course of 99mTc-DTPA when measured over 3 h has previously been shown. This study was performed to compare the kinetics of clearance of 99mTc-DTPA, measured for 3 h, in sarcoid patients and healthy smokers. Forty-one never-smoking patients with sarcoidosis and radiological signs of intrathoracic disease were studied. The results were compared with those of 16 healthy current smokers and of 14 healthy never-smokers reported previously. A mono-exponential clearance equation described the clearance in 22 of the sarcoid patients and all normal never-smokers, but with a shorter average tracer half-life in the patients (P<0.05). In 19 patients and all smokers a bi-exponential equation gave a significantly better curve fit. The rate of clearance of the slow component was higher in patients with sarcoidosis than in smokers (P< 0.05). The fraction of the tracer cleared by the fast clearance component was smaller in patients with sarcoidosis than in smokers (P<0.01). Differences in kinetics of clearance of 99mTc-DTPA in sarcoidosis and smoking could thus be demonstrated, suggesting that the abnormal clearance is caused by diverging pathophysiological mechanisms.

A method for measuring attenuation coefficients in single-photon emission tomography (SPECT) is described and evaluated, together with a method for attenuation correction using these measured attenuation coefficients. Build-up, caused by scattered photons, is corrected for by a simple substitution in the algorithms. Transmission studies are performed with a99mTc- or57Co flood source, and emission phantom studies with99mTc line sources. The method is evaluated with variable but well-defined phantoms. The result is accurate attenuation coefficients for different densities, dimensions and geometries, and an accuracy of corrected emission activities of better than ∓ 10% in most cases. The present limitations of the method for attenuation correction are discussed.

We measured lung density by means of x-ray computed tomography and lung mechanics in 33 workers exposed to asbestos cement and in 39 normal subjects. The exposed group showed evidence of lung fibrosis with reduced static lung volumes and lung compliance, although only three subjects had signs of interstitial fibrosis at standard chest radiography. Lung density was significantly increased in the exposed workers compared to control subjects, with greater differences between nonsmokers than between smokers. Lung density correlated inversely with static lung volumes. There was no appreciable difference in the regional distribution of lung density between exposed workers and control subjects. We conclude that lung density is often increased in workers with mild asbestosis, even in the presence of a normal chest radiograph. Measurement of lung density may be of value in the evaluation of asbestos-exposed workers for assessment of the extent of parenchymal disease.

The spontaneous rate of the middle ear ventilation through the Eustachian tube in the aural flow direction was determined on 3 normal subjects for some hour by a pressure-flow technique. This rate of ventilation was considered to reflect the normal rate of gas volume absorption from the middle ear space to the blood. Assuming that the rate of ventilation determined is valid for 24 hours, the daily ventilation through the Eustachian tube into the middle ear for obtaining normal ear pressure conditions only reaches 1 - 2 ml.Finally two accessory mechanisms are discussed which may facilitate the ventilation of the middle ear.

The article focuses on the recognition of the Uddmanska House as a historic site by the European Physical Society (EPS) on October 29, 2016 in Kungälv, Sweden. It provides overview of the history of the house and the experience of Austrian physicist Lise Meitner and her nephew Otto Frisch in spending their Christmas holidays in 1938 at the house. It also mentions the factors that made the house one of the historic sites of the EPS.

The addition of K2SO4to Li2SO4causes a considerable change in the rheological properties of the cubic high temperature modification. A simple device for relative measurements of the plastic flow of the salt consisted of a sphere of stainless steel at the end of a steel rod on top of which weights were hung in order to obtain a suitable penetration rate through the salt. This rate depended on the composition of the mixture as well as on the thermal pretreatment of the salt. The temperature dependence was strong; a crude estimation gave an “activation energy” of the order of 2 x 105cal/mole, i. e. more than an order of magnitude higher than for electrical conductivity or cation self-diffusion. This result is in agreement with the interpretation of the electrical conductivity as being due solely to cation transport.

Dead space negatively influences carbon dioxide (CO2) elimination, particularly at high respiratory rates (RR) used at low tidal volume ventilation in acute respiratory distress syndrome (ARDS). Aspiration of dead space (ASPIDS), a known method for dead space reduction, comprises two mechanisms activated during late expiration: aspiration of gas from the tip of the tracheal tube and gas injection through the inspiratory line - circuit flushing. The objective was to study the efficiency of circuit flushing alone and of ASPIDS at wide combinations of RR and tidal volume (VT) in anaesthetized pigs. The hypothesis was tested that circuit flushing and ASPIDS are particularly efficient at high RR.

Introduction Alveolar dead space reflects phenomena that render arterial partial pressure of carbon dioxide higher than that of mixed alveolar gas, disturbing carbon dioxide exchange. Right-to-left shunt fraction (Qs/Qt) leads to an alveolar dead space fraction (VdAS/VtA; where VtA is alveolar tidal volume). In acute respiratory distress syndrome, ancillary physiological disturbances may include low cardiac output, high metabolic rate, anaemia and acid-base instability. The purpose of the present study was to analyze the extent to which shunt contributes to alveolar dead space and perturbs carbon dioxide exchange in ancillary physiological disturbances.Methods A comprehensive model of pulmonary gas exchange was based upon known equations and iterative mathematics.Results The alveolar dead space fraction caused by shunt increased nonlinearly with Qs/Qt and, under 'basal conditions', reached 0.21 at a Qs/Qt of 0.6. At a Qs/Qt of 0.4, reduction in cardiac output from 5 l/minute to 3 l/minute increased VdAS/VtA from 0.11 to 0.16. Metabolic acidosis further augmented the effects of shunt on VdAS/VtA, particularly with hyperventilation. A Qs/Qt of 0.5 may increase arterial carbon dioxide tension by about 15% to 30% if ventilation is not increased.Conclusion In acute respiratory distress syndrome, perturbation of carbon dioxide exchange caused by shunt is enhanced by ancillary disturbances such as low cardiac output, anaemia, metabolic acidosis and hyperventilation. Maintained homeostasis mitigates the effects of shunt.

Introduction To prevent further lung damage in patients with acute respiratory distress syndrome (ARDS), it is important to avoid overdistension and cyclic opening and closing of atelectatic alveoli. Previous studies have demonstrated protective effects of using low tidal volume (VT), moderate positive end-expiratory pressure and low airway pressure. Aspiration of dead space (ASPIDS) allows a reduction in VT by eliminating dead space in the tracheal tube and tubing. We hypothesized that, by applying goal-orientated ventilation based on iterative computer simulation, VT can be reduced at high respiratory rate and much further reduced during ASPIDS without compromising gas exchange or causing high airway pressure.Methods ARDS was induced in eight pigs by surfactant perturbation and ventilator-induced lung injury. Ventilator resetting guided by computer simulation was then performed, aiming at minimal VT, plateau pressure 30 cmH2O and isocapnia, first by only increasing respiratory rate and then by using ASPIDS as well.Results VT decreased from 7.2 ± 0.5 ml/kg to 6.6 ± 0.5 ml/kg as respiratory rate increased from 40 to 64 ± 6 breaths/min, and to 4.0 ± 0.4 ml/kg when ASPIDS was used at 80 ± 6 breaths/min. Measured values of arterial carbon dioxide tension were close to predicted values. Without ASPIDS, total positive end-expiratory pressure and plateau pressure were slightly higher than predicted, and with ASPIDS they were lower than predicted.Conclusion In principle, computer simulation may be used in goal-oriented ventilation in ARDS. Further studies are needed to investigate potential benefits and limitations over extended study periods.