Global patient outcomes after elective surgery: prospective cohort study in 27 low-, middle- and high-income countries.

BACKGROUND: As global initiatives increase patient access to surgical treatments, there remains a need to understand the adverse effects of surgery and define appropriate levels of perioperative care. METHODS: We designed a prospective international 7-day cohort study of outcomes following elective adult inpatient surgery in 27 countries. The primary outcome was in-hospital complications. Secondary outcomes were death following a complication (failure to rescue) and death in hospital. Process measures were admission to critical care immediately after surgery or to treat a complication and duration of hospital stay. A single definition of critical care was used for all countries. RESULTS: A total of 474 hospitals in 19 high-, 7 middle- and 1 low-income country were included in the primary analysis. Data included 44 814 patients with a median hospital stay of 4 (range 2-7) days. A total of 7508 patients (16.8%) developed one or more postoperative complication and 207 died (0.5%). The overall mortality among patients who developed complications was 2.8%. Mortality following complications ranged from 2.4% for pulmonary embolism to 43.9% for cardiac arrest. A total of 4360 (9.7%) patients were admitted to a critical care unit as routine immediately after surgery, of whom 2198 (50.4%) developed a complication, with 105 (2.4%) deaths. A total of 1233 patients (16.4%) were admitted to a critical care unit to treat complications, with 119 (9.7%) deaths. Despite lower baseline risk, outcomes were similar in low- and middle-income compared with high-income countries. CONCLUSIONS: Poor patient outcomes are common after inpatient surgery. Global initiatives to increase access to surgical treatments should also address the need for safe perioperative care. STUDY REGISTRATION: ISRCTN5181700

Electron density and temperature measurements in a magnetized expanding hydrogen plasma

We report measurements of electron densities, n e , and temperatures, T e , in a magnetized expanding hydrogen plasma performed using Thomson scattering. The effects of applying an axial magnetic field and changing the background pressure in the plasma vessel on n e and T e along the expansion axis are reported. Magnetic field strengths (B field) up to 170 mT were applied, which are one order of magnitude larger than previously reported. The main effect of the applied B field is the plasma confinement, which leads to higher n e . At B fields larger than 88 mT the electron density along the expansion axis does not depend strongly on the magnetic field strength. However, T e is susceptible to the B field and reaches at 170 mT a maximum of 2.5 eV at a distance of 1.5 cm from the exit of the cascaded arc. To determine also the effect of the arc current through the arc, measurements were performed with arc currents of 45, 60, and 75 A at background pressures of 9.7 and 88.3 Pa. At constant magnetic field n e decreases from the exit of the arc along the expansion axis when the arc current is decreased. At 88.3 Pa n e shows a higher value close to the exit of the arc, but a faster decay along the expansion axis with respect to the 9.7 Pa case. T e is overall higher at lower pressure reaching a maximum of 3.2 eV at the lower arc current of 45 A. The results of this study complement our understanding and the characterization of expanding hydrogen plasmas.\u3cbr/\u3

Laser assisted electron gas heating: revision of the criterion for high pressure non-thermal plasmas

Lasers are commonly used nowadays to investigate the plasma properties (laser-aided plasma diagnostics LAPD). However, in using LAPD, one should always be careful in tuning the laser power density to avoid perturbation of the plasma during the diagnostic. A general formula was given by Kunze [1] to determine the heating of electrons during laser diagnostics via electron-ion inverse bremsstrahlung (IB). In this contribution, it is shown that for low ionization degree and high pressure plasmas, electron-ion IB is a negligible heating process and that electron-atom IB becomes dominant. The criterion for non-invasive LAPD needs then to be revised consequently

A power pulsed low-pressure argon microwave plasma investigated by Thomson scattering : evidence for molecular assisted recombination

A squared-wave power pulsed low-pressure plasma is investigated by means of Thomson scattering. By this method the values of the electron density and temperature are obtained, directly. The plasma is created by a surfatron launcher in pure argon at gas pressures of 8–70 mbar. Features of the pulse rise and decay are studied with microsecond time resolution. During the pulse rise we observe initial high temperature values, while the density is still rising. At power switch-off we find decay times of the electron density that are smaller than what is expected on the basis of diffusion losses. This implies that the dominant decay mechanism in the studied pressure regime is provided by molecular assisted recombination

Thomson Scattering on transient microwave induced plasmas

Abstract only

Polydiagnostic study on a surfatron plasma at atmospheric pressure

No abstract

Polydiagnostics performed on high-tech plasmas

The large effluxes generated by high-tech plasmas force plasmas to non-equilibrium conditions. This implies that plasma features are decoupled from each other and that therefore different methods have to be used quasi-simultaneously to characterize the plasma. Even more insight in plasmas and methods is obtained if polydiagnostics is applied to a series of plasma conditions that gradually differ in equilibrium departure. After discussing methods of passive and active spectroscopy, we apply polydiagnostics on an argon plasma operated in open air. By introducing H2 and reducing the power we approach conditions of cool atmospheric plasmas (CAPs). It is seen that especially the passive methods for the electron temperature determination are very sensitive to the degree of equilibrium departure suggesting that active spectroscopy is preferable. However, one should realize that lasers can easily heat cool plasmas.This is due to the fact that the ionization degree of (semi-) CAPs is small

Laser scattering techniques applied to cold atmospheric plasmas : trends and pitfalls

Cold atmospheric plasmas (CAPs) are a topic of growing interest nowadays, especially due to their applicability in material processing and biomedical applications. The laser scattering techniques of Thomson, Rayleigh and Raman provide precise measurements of the electron temperature, electron density, and the gas temperature. These laser scattering diagnostic methods are advantageous due to the high spatial and temporal resolution that they can achieve. In this contribution we aim to address the possibilities of laser scattering techniques as well as the main complications that come into play when they are applied to cold atmospheric discharges. A classical problem for Thomson scattering experiments is the false stray light, which might deteriorate the detection limit. As a consequence of their low gas temperature and open air operation, CAPs present high concentrations of molecules. This implies that the Thomson and Raman spectra will overlap, and therefore the two signals must be precisely disentangled. Another characteristic of CAPs is the low ionization degree which can induce deviations in the electron energy distribution function (EEDF). These deviations mainly affect the tail of the EEDF. An energy region that is not easy to measure by Thomson scattering. Finally, the laser heating of the electron gas is another issue which has to be considered. In the case of CAPs the contribution to the laser-heating intermediated by electron-atom collisions cannot be neglected. To place the specific features of laser scattering techniques in a broader perspective we will compare the CAP results to those obtained on low pressure plasmas

How the alternating degeneracy in rotational Raman spectra of CO\u3csub\u3e2\u3c/sub\u3e and C\u3csub\u3e2\u3c/sub\u3eH\u3csub\u3e2\u3c/sub\u3e reveals the vibrational temperature

\u3cp\u3eThe contribution of higher vibrational levels to the rotational spectrum of linear polyatomic molecules with a center of symmetry (CO\u3csub\u3e2\u3c/sub\u3e and C\u3csub\u3e2\u3c/sub\u3eH\u3csub\u3e2\u3c/sub\u3e) is assessed. An apparent nuclear degeneracy is analytically formulated by vibrational averaging and compared to numerical averaging over vibrational levels. It enables inferring the vibrational temperature of the bending and asymmetric stretching modes from the ratio of even to odd peaks in the rotational Raman spectrum. The contribution from higher vibrational levels is already observable at room temperature as g???\u3csub\u3ee\u3c/sub\u3e∕\u3csub\u3eo\u3c/sub\u3e 0.96∕0.04 for CO\u3csub\u3e2\u3c/sub\u3e and g???\u3csub\u3ee\u3c/sub\u3e∕\u3csub\u3eo\u3c/sub\u3e 1.16∕2.84 for C\u3csub\u3e2\u3c/sub\u3eH\u3csub\u3e2\u3c/sub\u3e. The use of the apparent degeneracy to account for higher vibrational levels is demonstrated on spectra measured for a CO\u3csub\u3e2\u3c/sub\u3e microwave plasma in the temperature range of 300–3500 K, and shown to be valid up to 1500 K.\u3c/p\u3

Relationship between fibrillin-1 genotype and severity of cardiovascular involvement in Marfan syndrome

Background The effect of FBN1 mutation type on the severity of cardiovascular manifestations in patients with Marfan syndrome (MFS) has been reported with disparity results. Objectives This study aims to determine the impact of the FBN1 mutation type on aortic diameters, aortic dilation rates and on cardiovascular events (ie, aortic dissection and cardiovascular mortality). Methods MFS patients with a pathogenic FBN1 mutation followed at two specialised units were included. FBN1 mutations were classified as being dominant negative (DN; incorporation of non-mutated and mutated fibrillin-1 in the extracellular matrix) or having haploinsufficiency (HI; only incorporation of non-mutated fibrillin-1, thus a decreased amount of fibrillin-1 protein). Aortic diameters and the aortic dilation rate at the level of the aortic root, ascending aorta, arch, descending thoracic aorta and abdominal aorta by echocardiography and clinical endpoints comprising dissection and death were compared between HI and DN patients. Results Two hundred and ninety patients with MFS were included: 113 (39%) with an HI-FBN1 mutation and 177 (61%) with a DN-FBN1. At baseline, patients with HI-FBN1 had a larger aortic root diameter than patients with DN-FBN1 (HI: 39.3±7.2 mm vs DN: 37.3±6.8 mm, p=0.022), with no differences in age or body surface area. After a mean follow-up of 4.9±2.0 years, aortic root and ascending dilation rates were increased in patients with HI-FBN1 (HI: 0.57±0.8 vs DN: 0.28±0.5 mm/year, p=0.004 and HI: 0.59±0.9 vs DN: 0.30±0.7 mm/year, p=0.032, respectively). Furthermore, patients with HI-FBN1 tended to be at increased risk for the combined endpoint of dissection and death compared with patients with DN-FBN1 (HR: 3.3, 95% CI 1.0 to 11.4, p=0.060). Conclusions Patients with an HI mutation had a more severely affected aortic phenotype, with larger aortic root diameters and a more rapid dilation rate, and tended to have an increased risk of death and dissections compared with patients with a DN mutation