Sepsis incidence and outcome: contrasting the intensive care unit with the hospital ward

OBJECTIVE

To describe the outcome of patients with sepsis according to location on a ward or in an intensive care unit.

DESIGN

Prospective multicentered observational study.

SETTING

Three academic hospitals in Madrid, Spain.

PATIENTS

Consecutive patients with sepsis admitted to participating hospitals from March 1 to June 30, 2003.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

During the study period, 15,852 patients >18 yrs of age were admitted. Sepsis was identified in 702 patients, giving an estimated cumulative incidence rate of 367 cases per 100,000 adult area residents per year and a cumulative incidence rate among patients admitted to the hospital of 4.4%. Most septic patients had a community-acquired infection (71%). Severe sepsis developed in 199 patients (incidence rate, 104 cases per 100,000 adult area residents per year), and 59 patients developed septic shock (incidence rate, 31 cases per 100,000 adult area residents per year). Most of the patients met the criteria for severe sepsis or septic shock on the same day that they would have qualified for the septic status one step down the scale. In the other patients, the median time between sepsis and severe sepsis was 2 days (interquartile range, 2-5) and between severe sepsis and septic shock was 3 days (interquartile range, 1-4). Only 32% of severe sepsis patients received intensive care. The hospital mortality for all septic patients was 12.8%; for severe sepsis, 20.7%; and for septic shock, 45.7%.

CONCLUSIONS

This study shows the high incidence of sepsis in a general population of patients admitted to hospital. A significant proportion of patients with severe sepsis are not transferred to the intensive care unit.

Evidence for a spin-aligned neutron-proton paired phase from the level structure of (92)Pd

Shell structure and magic numbers in atomic nuclei were generally explained by pioneering work that introduced a strong spin-orbit interaction to the nuclear shell model potential. However, knowledge of nuclear forces and the mechanisms governing the structure of nuclei, in particular far from stability, is still incomplete. In nuclei with equal neutron and proton numbers (N = Z), enhanced correlations arise between neutrons and protons (two distinct types of fermions) that occupy orbitals with the same quantum numbers. Such correlations have been predicted to favour an unusual type of nuclear superfluidity, termed isoscalar neutron-proton pairing, in addition to normal isovector pairing. Despite many experimental efforts, these predictions have not been confirmed. Here we report the experimental observation of excited states in the N = Z = 46 nucleus (92)Pd. Gamma rays emitted following the (58)Ni((36)Ar,2n)(92)Pd fusion-evaporation reaction were identified using a combination of state-of-the-art high-resolution γ-ray, charged-particle and neutron detector systems. Our results reveal evidence for a spin-aligned, isoscalar neutron-proton coupling scheme, different from the previous prediction. We suggest that this coupling scheme replaces normal superfluidity (characterized by seniority coupling) in the ground and low-lying excited states of the heaviest N = Z nuclei. Such strong, isoscalar neutron-proton correlations would have a considerable impact on the nuclear level structure and possibly influence the dynamics of rapid proton capture in stellar nucleosynthesis.

Clinical risk conditions for acute lung injury in the intensive care unit and hospital ward: a prospective observational study

BACKGROUND

Little is known about the development of acute lung injury outside the intensive care unit. We set out to document the following: the association between predefined clinical conditions and the development of acute lung injury by using the American-European consensus definition; the frequency of lung injury development outside the intensive care unit; and the temporal relationship between antecedent clinical risk conditions, intensive care admission, and diagnosis of lung injury.

METHODS

We conducted a 4-month prospective observational study in three Spanish teaching hospitals, enrolling consecutive patients who developed clinical conditions previously linked to lung injury, both inside and outside the intensive care unit. Patients were followed prospectively for outcomes, including the diagnosis of acute lung injury or acute respiratory distress syndrome.

RESULTS

A total 815 patients were identified with at least one clinical insult; the most common were sepsis, pneumonia, and pancreatitis. Pulmonary risk conditions were observed in 30% of cases. Fifty-three patients (6.5%) developed acute lung injury; 33 of these (4.0%) met criteria for acute respiratory distress syndrome. Lung injury occurred most commonly in the setting of sepsis (46/53; 86.7%), but shock (21/59; 36%) and pneumonia (20/211; 9.5%) portended the highest proportional risk; this risk was higher in patients with increasing numbers of clinical risk conditions (2.2%, 14%, and 21% (P < 0.001) in patients with one, two, and three conditions, respectively). Median days (interquartile range) from risk condition to diagnosis of lung injury was shorter with pulmonary (0 (0 to 2)) versus extrapulmonary (3 (1 to 5)) (P = 0.029) risk conditions. Admission to the intensive care unit was provided to 9/20 (45%) patients with acute lung injury and to 29/33 (88%) of those with acute respiratory distress syndrome. Lung injury patients had higher mortality than others (acute lung injury 25.0%; acute respiratory distress syndrome 45.5%; others 10.3%; P < 0.001).

CONCLUSION

The time course from clinical insult to diagnosis of lung injury was rapid, but may be longer for extrapulmonary cases. Some patients with lung injury receive care and die outside the intensive care unit; this observation needs further study.

Noninvasive vs conventional mechanical ventilation in acute respiratory failure: a multicenter, randomized controlled trial

STUDY OBJECTIVE

Noninvasive mechanical ventilation (NIMV) is beneficial for patients with acute respiratory failure (ARF) when added to medical treatment. However, its role as an alternative to conventional mechanical ventilation (CMV) remains controversial. Our aim was to compare the efficacy and resource consumption of NIMV against CMV in patients with ARF.

DESIGN

A randomized, multicenter, controlled trial.

SETTING

Seven multipurpose ICUs.

PATIENTS

Sixty-four patients with ARF from various causes who fulfilled criteria for mechanical ventilation.

INTERVENTION

The noninvasive group received ventilation through a face mask in pressure-support mode plus positive end-expiratory pressure; the conventional group received ventilation through a tracheal tube.

MEASUREMENTS AND RESULTS

Avoidance of intubation, mortality, and consumption of resources were the outcome variables. Thirty-one patients were assigned to the noninvasive group, and 33 were assigned to the conventional group. In the noninvasive group, 58% patients were intubated, vs 100% in the conventional group (relative risk reduction, 43%; p < 0.001). Stratification by type of ARF gave similar results. In the ICU, death occurred in 23% and 39% (p = 0.09) and complications occurred in 52% and 70% (p = 0.07) in the noninvasive and conventional groups, respectively. There were no differences in length of stay. The Therapeutic Intervention Score System-28, but not the direct nursing activity time, was lower in the noninvasive group during the first 3 days.

CONCLUSIONS

NIMV reduces the need for intubation and therapeutic intervention in patients with ARF from different causes. There is a nonsignificant trend of reduction in ICUs and hospital mortality together with fewer complications during ICU stay.

Reactor decay heat in 239Pu: solving the γ discrepancy in the 4-3000-s cooling period

The β feeding probability of (102,104,105,106,107)Tc, 105Mo, and 101Nb nuclei, which are important contributors to the decay heat in nuclear reactors, has been measured using the total absorption technique. We have coupled for the first time a total absorption spectrometer to a Penning trap in order to obtain sources of very high isobaric purity. Our results solve a significant part of a long-standing discrepancy in the γ component of the decay heat for 239Pu in the 4-3000 s range.

Septicaemia in a medical intensive care unit. Clinical, biochemical and microbiological data of 109 cases

Blood cultures were obtained from 39% of all 574 admissions to our Medical Intensive Care Unit. (ICU); in 109 (19%) a pathogenic organism was demonstrated. 45% of the septicaemias were detected within the first 48 h of ICU stay have been considered as "non ICU-acquired". Septicaemic patients were significantly older, had longer ICU stays and a higher mortality rate (62%) than non septicaemic patients (28%) (p less than 0.05). Gram negative organisms (69%) predominated over gram positive (29%) and Serratia marcescens and coagulase positive Staphylococcus were the most frequently isolated. Shock appeared in 32% and had an extremely high mortality (91%) and was associated with the presence of "multiple species septicaemia". Prior to the septicaemia the survivors differed from the fatalities only in the level of serum albumin; this was significantly lower in patients with gram negative in comparison with gram positive septicaemias and in patients who developed shock. Arterial, pulmonary artery and urinary catheters, and endotracheal devices were used frequently in these patients and were statistically associated with the presence of septicaemia. The airway was the most frequent possible source for the septicaemia.

New antineutrino energy spectra predictions from the summation of beta decay branches of the fission products

In this Letter, we study the impact of the inclusion of the recently measured beta decay properties of the (102;104;105;106;107)Tc, (105)Mo, and (101)Nb nuclei in an updated calculation of the antineutrino energy spectra of the four fissible isotopes (235,238)U and (239,241)Pu. These actinides are the main contributors to the fission processes in pressurized water reactors. The beta feeding probabilities of the above-mentioned Tc, Mo, and Nb isotopes have been found to play a major role in the γ component of the decay heat of (239)Pu, solving a large part of the γ discrepancy in the 4-3000 s range. They have been measured by using the total absorption technique, insensitive to the pandemonium effect. The calculations are performed by using the information available nowadays in the nuclear databases, summing all the contributions of the beta decay branches of the fission products. Our results provide a new prediction of the antineutrino energy spectra of (235)U, (239,241)Pu, and, in particular, (238)U for which no measurement has been published yet. We conclude that new total absorption technique measurements are mandatory to improve the reliability of the predicted spectra.

Total Absorption Spectroscopy Study of (92)Rb Decay: A Major Contributor to Reactor Antineutrino Spectrum Shape

The antineutrino spectra measured in recent experiments at reactors are inconsistent with calculations based on the conversion of integral beta spectra recorded at the ILL reactor. (92)Rb makes the dominant contribution to the reactor antineutrino spectrum in the 5-8 MeV range but its decay properties are in question. We have studied (92)Rb decay with total absorption spectroscopy. Previously unobserved beta feeding was seen in the 4.5-5.5 region and the GS to GS feeding was found to be 87.5(25)%. The impact on the reactor antineutrino spectra calculated with the summation method is shown and discussed.

[Intrahospital mortality after discharge from the ICU (hidden mortality) in patients who required mechanical ventilation]

BACKGROUND AND OBJECTIVE

Our goal was to determine the hidden mortality (HM) in patients who underwent an episode of mechanical ventilation (MV). We also analyzed the factors associated with an increase in the risk of hidden mortality.

PATIENTS AND METHOD

Prospective cohort study. Patients admitted to an ICU who required MV and who were monitored until their discharge from hospital. We performed a multivariate study with a logistic regression model including all the variables that were present in a univariate analysis p < 0.20.

RESULTS

Forty-one of the 215 patients who were discharged from the ICU died when they were admitted to hospital, which represents a hidden mortality rate of 19% (CI 95% 11%-27%). A mean period of 9 days elapsed between discharge from the ICU and patient's death, with 25% of patients dying within the first two days. Commonest cause of death was respiratory failure (37%). Factors independently associated with an increase in the risk of hidden mortality were (values expressed as adjusted odds ratio (CI 95%): age > 74 years 1.15 (1.01 to 1.26) (p = 0.02); APACHE II > 29 1.14 (1.01 to 1.27) (p = 0.04); reason for MV being coma 1.21 (1.07 to 1.37) (p = 0.002); reason for MV being cardiopulmonary arrest 1.28 (1.18 to 1.68) (p < 0.001); tracheotomy in ICU 1.31 (1.19 to 1.68) (p < 0.001) and stay in the ICU longer than 16 days 1.35 (1.01 to1.70) (p = 0.04).

CONCLUSIONS

An important number of patients discharged from the ICU after an episode of MV die in hospital. Risk factors associated with an increased risk of death in hospital identify a group of patients who, after excluding those with non-cardiopulmonary resuscitation orders, would possibly benefit from high surveillance or intermediate care units.

Enhanced γ-Ray Emission from Neutron Unbound States Populated in β Decay

Total absorption spectroscopy is used to investigate the β-decay intensity to states above the neutron separation energy followed by γ-ray emission in (87,88)Br and (94)Rb. Accurate results are obtained thanks to a careful control of systematic errors. An unexpectedly large γ intensity is observed in all three cases extending well beyond the excitation energy region where neutron penetration is hindered by low neutron energy. The γ branching as a function of excitation energy is compared to Hauser-Feshbach model calculations. For (87)Br and (88)Br the γ branching reaches 57% and 20%, respectively, and could be explained as a nuclear structure effect. Some of the states populated in the daughter can only decay through the emission of a large orbital angular momentum neutron with a strongly reduced barrier penetrability. In the case of neutron-rich (94)Rb the observed 4.5% branching is much larger than the calculations performed with standard nuclear statistical model parameters, even after proper correction for fluctuation effects on individual transition widths. The difference can be reconciled by introducing an enhancement of 1 order of magnitude in the photon strength to neutron strength ratio. An increase in the photon strength function of such magnitude for very neutron-rich nuclei, if it proves to be correct, leads to a similar increase in the (n,γ) cross section that would have an impact on r process abundance calculations.

Lifetime measurements of the neutron-rich N = 30 isotones 50Ca and 51Sc: orbital dependence of effective charges in the fp shell

The lifetimes of the first excited states of the N = 30 isotones (50)Ca and (51)Sc have been determined using the Recoil Distance Doppler Shift method in combination with the CLARA-PRISMA spectrometers. This is the first time such a method is applied to measure lifetimes of neutron-rich nuclei populated via a multinucleon transfer reaction. This extends the lifetime knowledge beyond the f_{7/2} shell closure and allows us to derive the effective proton and neutron charges in the fp shell near the doubly magic nucleus (48)Ca, using large-scale, shell-model calculations. These results indicate an orbital dependence of the core polarization along the fp shell.

New isomers in the full seniority scheme of neutron-rich lead isotopes: the role of effective three-body forces

The neutron-rich lead isotopes, up to (216)Pb, have been studied for the first time, exploiting the fragmentation of a primary uranium beam at the FRS-RISING setup at GSI. The observed isomeric states exhibit electromagnetic transition strengths which deviate from state-of-the-art shell-model calculations. It is shown that their complete description demands the introduction of effective three-body interactions and two-body transition operators in the conventional neutron valence space beyond (208)Pb.

Updated Summation Model: An Improved Agreement with the Daya Bay Antineutrino Fluxes

A new summation method model of the reactor antineutrino energy spectrum is presented. It is updated with the most recent evaluated decay databases and with our total absorption gamma-ray spectroscopy measurements performed during the last decade. For the first time, the spectral measurements from the Daya Bay experiment are compared with the antineutrino energy spectrum computed with the updated summation method without any renormalization. The results exhibit a better agreement than is obtained with the Huber-Mueller model in the 2-5 MeV range, the region that dominates the detected flux. A systematic trend is found in which the antineutrino flux computed with the summation model decreases with the inclusion of more pandemonium-free data. The calculated flux obtained now lies only 1.9% above that detected in the Daya Bay experiment, a value that may be reduced with forthcoming new pandemonium-free data, leaving less room for a reactor anomaly. Eventually, the new predictions of individual antineutrino spectra for the ^{235}U, ^{239}Pu, ^{241}Pu, and ^{238}U are used to compute the dependence of the reactor antineutrino spectral shape on the fission fractions.

Coulomb excitation of 104Sn and the strength of the 100Sn shell closure

A measurement of the reduced transition probability for the excitation of the ground state to the first 2+ state in 104Sn has been performed using relativistic Coulomb excitation at GSI. 104Sn is the lightest isotope in the Sn chain for which this quantity has been measured. The result is a key point in the discussion of the evolution of nuclear structure in the proximity of the doubly magic nucleus 100Sn. The value B(E2; 0+ → 2+) = 0.10(4) e2b2 is significantly lower than earlier results for 106Sn and heavier isotopes. The result is well reproduced by shell model predictions and therefore indicates a robust N = Z = 50 shell closure.

Angular momentum generation in nuclear fission

When a heavy atomic nucleus splits (fission), the resulting fragments are observed to emerge spinning¹; this phenomenon has been a mystery in nuclear physics for over 40 years^2,3. The internal generation of typically six or seven units of angular momentum in each fragment is particularly puzzling for systems that start with zero, or almost zero, spin. There are currently no experimental observations that enable decisive discrimination between the many competing theories for the mechanism that generates the angular momentum^4-12. Nevertheless, the consensus is that excitation of collective vibrational modes generates the intrinsic spin before the nucleus splits (pre-scission). Here we show that there is no significant correlation between the spins of the fragment partners, which leads us to conclude that angular momentum in fission is actually generated after the nucleus splits (post-scission). We present comprehensive data showing that the average spin is strongly mass-dependent, varying in saw-tooth distributions. We observe no notable dependence of fragment spin on the mass or charge of the partner nucleus, confirming the uncorrelated post-scission nature of the spin mechanism. To explain these observations, we propose that the collective motion of nucleons in the ruptured neck of the fissioning system generates two independent torques, analogous to the snapping of an elastic band. A parameterization based on occupation of angular momentum states according to statistical theory describes the full range of experimental data well. This insight into the role of spin in nuclear fission is not only important for the fundamental understanding and theoretical description of fission, but also has consequences for the γ-ray heating problem in nuclear reactors^13,14, for the study of the structure of neutron-rich isotopes^15,16, and for the synthesis and stability of super-heavy elements^17,18.

Observation of low- and high-energy Gamow-Teller phonon excitations in nuclei

Gamow-Teller (GT) transitions in atomic nuclei are sensitive to both nuclear shell structure and effective residual interactions. The nuclear GT excitations were studied for the mass number A = 42, 46, 50, and 54 "f-shell" nuclei in ((3)He, t) charge-exchange reactions. In the (42)Ca → (42)Sc reaction, most of the GT strength is concentrated in the lowest excited state at 0.6 MeV, suggesting the existence of a low-energy GT phonon excitation. As A increases, a high-energy GT phonon excitation develops in the 6-11 MeV region. In the (54)Fe → (54)Co reaction, the high-energy GT phonon excitation mainly carries the GT strength. The existence of these two GT phonon excitations are attributed to the 2 fermionic degrees of freedom in nuclei.

Half-life systematics across the N=126 shell closure: role of first-forbidden transitions in the β decay of heavy neutron-rich nuclei

This Letter reports on a systematic study of β-decay half-lives of neutron-rich nuclei around doubly magic (208)Pb. The lifetimes of the 126-neutron shell isotone (204)Pt and the neighboring (200-202)Ir, (203)Pt, (204)Au are presented together with other 19 half-lives measured during the "stopped beam" campaign of the rare isotope investigations at GSI collaboration. The results constrain the main nuclear theories used in calculations of r-process nucleosynthesis. Predictions based on a statistical macroscopic description of the first-forbidden β strength reveal significant deviations for most of the nuclei with N<126. In contrast, theories including a fully microscopic treatment of allowed and first-forbidden transitions reproduce more satisfactorily the trend in the measured half-lives for the nuclei in this region, where the r-process pathway passes through during β decay back to stability.

Observation of the β-delayed γ-proton decay of (56)Zn and its impact on the Gamow-Teller strength evaluation

We report the observation of a very exotic decay mode at the proton drip line, the β-delayed γ-proton decay, clearly seen in the β decay of the T_{z}=-2 nucleus ^{56}Zn. Three γ-proton sequences have been observed after the β decay. Here this decay mode, already observed in the sd shell, is seen for the first time in the fp shell. Both γ and proton decays have been taken into account in the estimation of the Fermi and Gamow-Teller strengths. Evidence for fragmentation of the Fermi strength due to strong isospin mixing is found.

Experimental Evidence for Transverse Wobbling in ^{105}Pd

New rotational bands built on the ν(h_{11/2}) configuration have been identified in ^{105}Pd. Two bands built on this configuration show the characteristics of transverse wobbling: the ΔI=1 transitions between them have a predominant E2 component and the wobbling energy decreases with increasing spin. The properties of the observed wobbling bands are in good agreement with theoretical results obtained using constrained triaxial covariant density functional theory and quantum particle rotor model calculations. This provides the first experimental evidence for transverse wobbling bands based on a one-neutron configuration, and also represents the first observation of wobbling motion in the A∼100 mass region.

Coulomb energy differences in t = 1 mirror rotational bands in (50)Fe and (50)Cr

Gamma rays from the N = Z-2 nucleus (50)Fe have been observed, establishing the rotational ground state band up to the state J(pi) = 11+ at 6.994 MeV excitation energy. The experimental Coulomb energy differences, obtained by comparison with the isobaric analog states in its mirror (50)Cr, confirm the qualitative interpretation of the backbending patterns in terms of successive alignments of proton and neutron pairs. A quantitative agreement with experiment has been achieved by exact shell model calculations, incorporating the differences in radii along the yrast bands, and properly renormalizing the Coulomb matrix elements in the pf model space.

Deformation of the N=Z nucleus 76Sr using beta-decay studies

A novel method of deducing the deformation of the N=Z nucleus 76Sr is presented. It is based on the comparison of the experimental Gamow-Teller strength distribution B(GT) from its beta decay with the results of quasi-random-phase approximation calculations. This method confirms previous indications of the strong prolate deformation of this nucleus in a totally independent way. The measurement has been carried out with a large total absorption gamma spectrometer, "Lucrecia," newly installed at CERN-ISOLDE.

First Measurement of Several β-Delayed Neutron Emitting Isotopes Beyond N=126

The β-delayed neutron emission probabilities of neutron rich Hg and Tl nuclei have been measured together with β-decay half-lives for 20 isotopes of Au, Hg, Tl, Pb, and Bi in the mass region N≳126. These are the heaviest species where neutron emission has been observed so far. These measurements provide key information to evaluate the performance of nuclear microscopic and phenomenological models in reproducing the high-energy part of the β-decay strength distribution. This provides important constraints on global theoretical models currently used in r-process nucleosynthesis.