Measurement of the ν_{e}-Nucleus Charged-Current Double-Differential Cross Section at ⟨E_{ν}⟩=2.4 GeV Using NOvA

The inclusive electron neutrino charged-current cross section is measured in the NOvA near detector using 8.02×10^{20} protons-on-target in the NuMI beam. The sample of GeV electron neutrino interactions is the largest analyzed to date and is limited by ≃17% systematic rather than the ≃7.4% statistical uncertainties. The double-differential cross section in final-state electron energy and angle is presented for the first time, together with the single-differential dependence on Q^{2} (squared four-momentum transfer) and energy, in the range 1  GeV≤E_{ν}<6  GeV. Detailed comparisons are made to the predictions of the GENIE, GiBUU, NEUT, and NuWro neutrino event generators. The data do not strongly favor a model over the others consistently across all three cross sections measured, though some models have especially good or poor agreement in the single differential cross section vs Q^{2}.

Search for Active-Sterile Antineutrino Mixing Using Neutral-Current Interactions with the NOvA Experiment

This Letter reports results from the first long-baseline search for sterile antineutrinos mixing in an accelerator-based antineutrino-dominated beam. The rate of neutral-current interactions in the two NOvA detectors, at distances of 1 and 810 km from the beam source, is analyzed using an exposure of 12.51×10^{20} protons-on-target from the NuMI beam at Fermilab running in antineutrino mode. A total of 121 of neutral-current candidates are observed at the far detector, compared to a prediction of 122±11(stat.)±15(syst.) assuming mixing only between three active flavors. No evidence for ν[over ¯]_{μ}→ν[over ¯]_{s} oscillation is observed. Interpreting this result within a 3+1 model, constraints are placed on the mixing angles θ_{24}<25° and θ_{34}<32° at the 90% C.L. for 0.05  eV^{2}≤Δm_{41}^{2}≤0.5  eV^{2}, the range of mass splittings that produces no significant oscillations at the near detector. These are the first 3+1 confidence limits set using long-baseline accelerator antineutrinos.

First measurement of neutrino oscillation parameters using neutrinos and antineutrinos by NOvA

The NOvA experiment has seen a 4.4σ signal of ν[over ¯]_{e} appearance in a 2 GeV ν[over ¯]_{μ} beam at a distance of 810 km. Using 12.33×10^{20} protons on target delivered to the Fermilab NuMI neutrino beamline, the experiment recorded 27 ν[over ¯]_{μ}→ν[over ¯]_{e} candidates with a background of 10.3 and 102 ν[over ¯]_{μ}→ν[over ¯]_{μ} candidates. This new antineutrino data are combined with neutrino data to measure the parameters |Δm_{32}^{2}|=2.48_{-0.06}^{+0.11}×10^{-3}  eV^{2}/c^{4} and sin^{2}θ_{23} in the ranges from (0.53-0.60) and (0.45-0.48) in the normal neutrino mass hierarchy. The data exclude most values near δ_{CP}=π/2 for the inverted mass hierarchy by more than 3σ and favor the normal neutrino mass hierarchy by 1.9σ and θ_{23} values in the upper octant by 1.6σ.

Publisher's Note: Identification of Nuclear Effects in Neutrino-Carbon Interactions at Low Three-Momentum Transfer [Phys. Rev. Lett. 116, 071802 (2016)]

This corrects the article DOI: 10.1103/PhysRevLett.116.071802.

Measurement of Final-State Correlations in Neutrino Muon-Proton Mesonless Production on Hydrocarbon at ⟨E_{ν}⟩=3 GeV

Final-state kinematic imbalances are measured in mesonless production of ν_{μ}+A→μ^{-}+p+X in the MINERvA tracker. Initial- and final-state nuclear effects are probed using the direction of the μ^{-}-p transverse momentum imbalance and the initial-state momentum of the struck neutron. Differential cross sections are compared to predictions based on current approaches to medium modeling. These models underpredict the cross section at intermediate intranuclear momentum transfers that generally exceed the Fermi momenta. As neutrino interaction models need to correctly incorporate the effect of the nucleus in order to predict neutrino energy resolution in oscillation experiments, this result points to a region of phase space where additional cross section strength is needed in current models, and demonstrates a new technique that would be suitable for use in fine-grained liquid argon detectors where the effect of the nucleus may be even larger.

Antineutrino Charged-Current Reactions on Hydrocarbon with Low Momentum Transfer

We report on multinucleon effects in low momentum transfer (<0.8  GeV/c) antineutrino interactions on plastic (CH) scintillator. These data are from the 2010-2011 antineutrino phase of the MINERvA experiment at Fermilab. The hadronic energy spectrum of this inclusive sample is well described when a screening effect at a low energy transfer and a two-nucleon knockout process are added to a relativistic Fermi gas model of quasielastic, Δ resonance, and higher resonance processes. In this analysis, model elements introduced to describe previously published neutrino results have quantitatively similar benefits for this antineutrino sample. We present the results as a double-differential cross section to accelerate the investigation of alternate models for antineutrino scattering off nuclei.

Measurement of Neutral-Current K^{+} Production by Neutrinos using MINERvA

Neutral-current production of K^{+} by atmospheric neutrinos is a background in searches for the proton decay p→K^{+}ν[over ¯]. Reactions such as νp→νK^{+}Λ are indistinguishable from proton decays when the decay products of the Λ are below detection threshold. Events with K^{+} are identified in MINERvA by reconstructing the timing signature of a K^{+} decay at rest. A sample of 201 neutrino-induced neutral-current K^{+} events is used to measure differential cross sections with respect to the K^{+} kinetic energy, and the non-K^{+} hadronic visible energy. An excess of events at low hadronic visible energy is observed relative to the prediction of the neut event generator. Good agreement is observed with the cross section prediction of the genie generator. A search for photons from π^{0} decay, which would veto a neutral-current K^{+} event in a proton decay search, is performed, and a 2σ deficit of detached photons is observed relative to the genie prediction.

Measurement of the Neutrino Mixing Angle θ_{23} in NOvA

This Letter reports new results on muon neutrino disappearance from NOvA, using a 14 kton detector equivalent exposure of 6.05×10^{20} protons on target from the NuMI beam at the Fermi National Accelerator Laboratory. The measurement probes the muon-tau symmetry hypothesis that requires maximal θ_{23} mixing (θ_{23}=π/4). Assuming the normal mass hierarchy, we find Δm_{32}^{2}=(2.67±0.11)×10^{-3}  eV^{2} and sin^{2}θ_{23} at the two statistically degenerate values 0.404_{-0.022}^{+0.030} and 0.624_{-0.030}^{+0.022}, both at the 68% confidence level. Our data disfavor the maximal mixing scenario with 2.6σ significance.

Evidence for Neutral-Current Diffractive π^{0} Production from Hydrogen in Neutrino Interactions on Hydrocarbon

The MINERvA experiment observes an excess of events containing electromagnetic showers relative to the expectation from Monte Carlo simulations in neutral-current neutrino interactions with mean beam energy of 4.5 GeV on a hydrocarbon target. The excess is characterized and found to be consistent with neutral-current π^{0} production with a broad energy distribution peaking at 7 GeV and a total cross section of 0.26±0.02(stat.)±0.08(sys.)×10^{-39}  cm^{2}. The angular distribution, electromagnetic shower energy, and spatial distribution of the energy depositions of the excess are consistent with expectations from neutrino neutral-current diffractive π^{0} production from hydrogen in the hydrocarbon target. These data comprise the first direct experimental observation and constraint for a reaction that poses an important background process in neutrino-oscillation experiments searching for ν_{μ} to ν_{e} oscillations.

Evidence of Coherent K^{+} Meson Production in Neutrino-Nucleus Scattering

Neutrino-induced charged-current coherent kaon production ν_{μ}A→μ^{-}K^{+}A is a rare, inelastic electroweak process that brings a K^{+} on shell and leaves the target nucleus intact in its ground state. This process is significantly lower in rate than the neutrino-induced charged-current coherent pion production because of Cabibbo suppression and a kinematic suppression due to the larger kaon mass. We search for such events in the scintillator tracker of MINERvA by observing the final state K^{+}, μ^{-}, and no other detector activity, and by using the kinematics of the final state particles to reconstruct the small momentum transfer to the nucleus, which is a model-independent characteristic of coherent scattering. We find the first experimental evidence for the process at 3σ significance.

Measurement of Electron Neutrino Quasielastic and Quasielasticlike Scattering on Hydrocarbon at ⟨E_{ν}⟩=3.6 GeV

The first direct measurement of electron neutrino quasielastic and quasielasticlike scattering on hydrocarbon in the few-GeV region of incident neutrino energy has been carried out using the MINERvA detector in the NuMI beam at Fermilab. The flux-integrated differential cross sections in the electron production angle, electron energy, and Q^{2} are presented. The ratio of the quasielastic, flux-integrated differential cross section in Q^{2} for ν_{e} with that of similarly selected ν_{μ}-induced events from the same exposure is used to probe assumptions that underpin conventional treatments of charged-current ν_{e} interactions used by long-baseline neutrino oscillation experiments. The data are found to be consistent with lepton universality and are well described by the predictions of the neutrino event generator GENIE.

Identification of Nuclear Effects in Neutrino-Carbon Interactions at Low Three-Momentum Transfer

Two different nuclear-medium effects are isolated using a low three-momentum transfer subsample of neutrino-carbon scattering data from the MINERvA neutrino experiment. The observed hadronic energy in charged-current ν_{μ} interactions is combined with muon kinematics to permit separation of the quasielastic and Δ(1232) resonance processes. First, we observe a small cross section at very low energy transfer that matches the expected screening effect of long-range nucleon correlations. Second, additions to the event rate in the kinematic region between the quasielastic and Δ resonance processes are needed to describe the data. The data in this kinematic region also have an enhanced population of multiproton final states. Contributions predicted for scattering from a nucleon pair have both properties; the model tested in this analysis is a significant improvement but does not fully describe the data. We present the results as a double-differential cross section to enable further investigation of nuclear models. Improved description of the effects of the nuclear environment are required by current and future neutrino oscillation experiments.

Cow, sheep and llama manure at psychrophilic anaerobic co-digestion with low cost tubular digesters in cold climate and high altitude

The aim of this research is to evaluate the co-digestion of cow and llama manure combined with sheep manure, in psychrophilic conditions and real field low cost tubular digesters adapted to cold climate. Four digesters were monitored in cold climate conditions; one fed with cow manure, a second one with llama manure, the third one with co-digestion of cow-sheep manure and the fourth one was fed with llama-sheep manure. The slurry had a mean temperature of 16.6 °C, the organic load rate was 0.44 kgvs m(-3) d(-1) and the hydraulic retention time was 80 days. After one hundred days biogas production was stable, as was the methane content and the pH of the effluent. The co-digestion of cow-sheep manure results in a biogas production increase of 100% compared to the mono-digestion of cow manure, while co-digestion of llama-sheep manure results in a decrease of 50% in biogas production with respect to mono-digestion of llama manure.

Measurement of coherent production of π(±) in neutrino and antineutrino beams on carbon from Eν of 1.5 to 20 GeV

Neutrino-induced coherent charged pion production on nuclei νμA→μ(±)π(∓)A is a rare, inelastic interaction in which a small squared four-momentum |t| is transferred to the recoil nucleus, leaving it intact in the reaction. In the scintillator tracker of MINERvA, we remove events with evidence of particles from nuclear breakup and reconstruct |t| from the final-state pion and muon. We select low |t| events to isolate a sample rich in coherent candidates. By selecting low |t| events, we produce a model-independent measurement of the differential cross section for coherent scattering of neutrinos and antineutrinos on carbon. We find poor agreement with the predicted kinematics in neutrino generators used by current oscillation experiments.

Improvement through low cost biofilm carrier in anaerobic tubular digestion in cold climate regions

The aim of this research is to evaluate the increase of biogas production with low cost tubular digesters in cold climates using PET rings inside the reactor. Two similar digesters have been operated and monitored in cold weather conditions and have been fed with cow manure. Digester 1 was filled with PET - rings as a biofilm carrier, Digester 2 was kept as a reference. Through the PET - rings the functional surface could be increased by a factor 4.2. The results show that 44% more biogas per Kg SV has been produced with the biofilm carrier in use (0.33 m(3)/kg SV) (reference digester -0.23 m(3)/kg SV), at an organic load rate of 0.26 kg SV/m(3)/d. The thermal performance shows that with an adaptation of the low cost tubular digester the slurry temperature can be raised up to 16.6°C (average) by surrounding temperature of 6.1°C (average) without using any active heating system.

Measurement of ratios of νμ charged-current cross sections on C, Fe, and Pb to CH at neutrino energies 2-20 GeV

We present measurements of ν(μ) charged-current cross section ratios on carbon, iron, and lead relative to a scintillator (CH) using the fine-grained MINERvA detector exposed to the NuMI neutrino beam at Fermilab. The measurements utilize events of energies 2<E(ν)<20 GeV, with ⟨E(ν)⟩ = 8 GeV, which have a reconstructed μ(-) scattering angle less than 17° to extract ratios of inclusive total cross sections as a function of neutrino energy E(ν) and flux-integrated differential cross sections with respect to the Bjorken scaling variable x. These results provide the first high-statistics direct measurements of nuclear effects in neutrino scattering using different targets in the same neutrino beam. Measured cross section ratios exhibit a relative depletion at low x and enhancement at large x. Both become more pronounced as the nucleon number of the target nucleus increases. The data are not reproduced by GENIE, a conventional neutrino-nucleus scattering simulation, or by the alternative models for the nuclear dependence of inelastic scattering that are considered.

Measurement of muon neutrino quasielastic scattering on a hydrocarbon target at Eν ~ 3.5 GeV

We report a study of ν(μ) charged-current quasielastic events in the segmented scintillator inner tracker of the MINERvA experiment running in the NuMI neutrino beam at Fermilab. The events were selected by requiring a μ- and low calorimetric recoil energy separated from the interaction vertex. We measure the flux-averaged differential cross section, dσ/dQ², and study the low energy particle content of the final state. Deviations are found between the measured dσ/dQ² and the expectations of a model of independent nucleons in a relativistic Fermi gas. We also observe an excess of energy near the vertex consistent with multiple protons in the final state.

Measurement of muon antineutrino quasielastic scattering on a hydrocarbon target at Eν ~ 3.5 GeV

We have isolated ν(μ) charged-current quasielastic (QE) interactions occurring in the segmented scintillator tracking region of the MINERvA detector running in the NuMI neutrino beam at Fermilab. We measure the flux-averaged differential cross section, dσ/dQ², and compare to several theoretical models of QE scattering. Good agreement is obtained with a model where the nucleon axial mass, M(A), is set to 0.99 GeV/c² but the nucleon vector form factors are modified to account for the observed enhancement, relative to the free nucleon case, of the cross section for the exchange of transversely polarized photons in electron-nucleus scattering. Our data at higher Q² favor this interpretation over an alternative in which the axial mass is increased.

The cuff method: a pilot study of a new method of monitoring neuromuscular function

BACKGROUND

A new method of monitoring neuromuscular blockade based on a modified blood pressure cuff that incorporates stimulating electrodes was compared with mechanomyography (MMG) ('gold standard').

METHODS

Forty adults and 20 children (ASA I-II) underwent neuromuscular blockade monitoring on the contralateral arms and on the same arm using the new cuff method and MMG. Only train-of-four (TOF) ratios > 0.1 and T(1) heights > 0 were studied. Supramaximal stimulation was also assessed. A device based on a PC with an analogue-to-digital conversion card was used to control and synchronize MMG and the cuff method. The agreement between both methods was assessed using the statistical method of Bland and Altman.

RESULTS

When TOF ratios were >0.7, the bias between the two methods was -0.04 with the limits of agreement ranging from -0.21 to -0.12 (95% CI -0.06 to -0.02). The T(1) > 0 heights bias was -0.01 with the limits of agreement ranging from -0.26 to 0.24 (95% CI -0.02 to -0.003). The sensitivity of the cuff method was 88%, with a specificity of 85% and an accuracy of 86%.

CONCLUSION

This pilot study indicates that the cuff method could be useful to monitor neuromuscular blockade according to the bias and limits of agreement compared with MMG, particularly when the degree of blockade was evaluated by TOF ratios > 0.7. The new cuff method is easy and simple to use. However, further studies in a larger number of patients are necessary to confirm these favourable preliminary results.

Right-sided endocarditis complicating an atrial septal defect

We report the case of a 45-year-old male patient not addicted to narcotic who presented with an infective endocarditis on the pulmonary valve. He was found to have an uncomplicated secundum-type atrial septal defect. This association is an extremely rare event.

[Laparoscopic resection of hepatic hydatid cyst under general anesthesia with remifentanil infusion]

We report the case of a 52-year-old woman who underwent scheduled laparoscopic resection of a hydatid liver cyst under general anesthesia by infusion of remifentanil and sevoflurane. Surgery was uneventful, although invasive monitoring was required, just as it would have been in major open abdominal surgery, given the risk of bleeding secondary to organ manipulation, the risk of anaphylactic shock related to the etiology of the cyst and the possibility of gas embolism related to laparoscopy. The concept of "minimally invasive" surgery has developed thanks to continued progress in laparoscopy. The considerable advantages of such procedures in comparison with "open" or "conventional" surgery has led to their use with organs such as the liver, which in principle require caution. In such cases, the anesthesiologist must take an approach that is not as simple or minimalist as the term "minimally invasive" might lead us to expect.

Prevalence of pain in the Spanish population: telephone survey in 5000 homes

Pain has become the most common accompanying symptom in patients seeking medical advice, and it is one of the main issues in public health. In Spain, there are no reliable data about the impact of pain in general population. The aim of the study was to estimate the prevalence of acute and chronic pain in the Spanish general population. An epidemiological observational population-based cross-sectional study was carried out by means of a telephone survey. Multistep stratified quota-adjusted sampling was performed with people aged 18-95 years. A computer-assisted questionnaire was administered, covering physical pain symptoms, site, frequency, perceived cause, therapeutic measures and interference with daily life activities. There were 11,980 useful contacts, with 5000 effective interviews (42% of useful sample). Of the interviewees, 29.6% (95% confidence interval, 28.3-30.8%) reported having had pain the day before (women, 37.6%; men, 20.9%) and 43.2% the week before. Most common pain sites were lower extremities (22.7%) and back (cervical and lumbar levels) (21.5%), followed by head (20.5%). Frequency of pain increased with age, reaching 42.6% for people older than 65 years. Among people complaining of pain during the last day or week, duration of symptoms was higher than 3 months in 54% (chronic pain), representing 23.4% of the Spanish general population; most common causes of chronic pain were arthritis, rheumatism and migraine. Regarding treatment, 61.7% of people complaining of pain said they were taking drugs. Source of drug treatment advice was a physician or a nurse in 66.4% of cases and self-prescription in 29%. It is concluded that pain, particularly chronic pain, has a high prevalence in the Spanish general population and a significant impact on occupational and social relationships.

[Nocardiosis in patients with HIV infection]

OBJECTIVE

To know the characteristics of nocardiosis in HIV infected patients.

PATIENTS AND METHODS

Retrospective analysis of HIV infected patients with a concomitant Nocardia spp. infection in nine Andalusian hospitals.

RESULTS

Eighteen cases of nocardiosis were studied. Seventeen patients were males and the mean age was 33.1 years. The risk behaviour for acquiring HIV infection was parenteral drug use in 15 patients (83.3%) and seven of them were active users when acquiring nocardiosis. The mean CD4 lymphocyte count was 66.3 106/l. The nocardiosis was manifested as disseminated disease in eight patients, only pulmonary disease in four cases, lymphocutaneous or soft-tissue nocardiosis in five, and pericarditis in the remaining patient. In the ten cases with pulmonary involvement, the chest X-ray revealed an alveolar, interstitial, and mixed pattern in five, three, and two patients, respectively. Most patients were treated with cotrimoxazole, with good clinical and microbiological responses in 88.8% of them. Some surgical procedures were required in six patients. Eight patients died, three on account of nocardiosis and five on account of other causes. There were three relapses.

CONCLUSIONS

Nocardia spp. infection is rare among patients with AIDS and occurs in immunosuppressed patients and drug users. The pulmonary, cutaneous, and soft-tissue were the most commonly observed forms in our series. Despite the high frequency of disseminated infection, the response to th

Usefulness of sputum culture for diagnosis of bacterial pneumonia in HIV-infected patients

The use of sputum culture in immunocompetent patients with community-acquired pneumonia is controversial. The usefulness of this technique in HIV-infected patients has not been evaluated. A prospective, observational, multicenter, hospital-based study of bacterial community-acquired pneumonia was carried out to analyze the value of sputum culture in HIV-infected patients. Only good-quality sputum samples were cultured. Altogether, 355 cases of bacterial community-acquired pneumonia were included. An etiological diagnosis was obtained in 190 (53.5%) cases. Sputum was cultured in 313 (88.1%) cases, being diagnostic in 108 (34.5%). The microorganism identified in sputum culture was the same as that identified in sterile samples in 26 of 27 (96.3%) cases in which both cultures were diagnostic. The microbiologic findings in sputum and bronchoscopic cultures were concordant in seven of eight (87.5%) cases in which both were positive. These results suggest that sputum culture is a useful technique, given its availability and ease of performance and its good correlation with culture of sterile samples.

Community-acquired bacterial pneumonia in human immunodeficiency virus-infected patients: validation of severity criteria. The Grupo Andaluz para el Estudio de las Enfermedades Infecciosas

Severity criteria for community-acquired pneumonia (CAP) have always excluded patients with human immunodeficiency virus (HIV) infection. A 1-yr, multicenter, prospective observational study of HIV-infected patients with bacterial CAP was done to validate the criteria used in the American Thoracic Society (ATS) guidelines for CAP, and to determine the prognosis-associated factors in the HIV-infected population with bacterial CAP. Overall, 355 cases were included, with an attributable mortality of 9.3%. Patients who met the ATS criteria had a longer hospital stay (p = 0.01), longer duration of fever (p < 0.001), and higher attributable mortality (13.1% versus 3.5%, p = 0.02) than those who did not. Three factors were independently related to mortality: CD4(+) cell count < 100/microl, radiologic progression of disease, and shock. Pleural effusion, cavities, and/or multilobar infiltrates at admission were independently associated with radiologic progression. A prognostic rule based on the five criteria of shock, CD4(+) cell count < 100/microl, pleural effusion, cavities, and multilobar infiltrates had a high negative predictive value for mortality (97.1%). The attributable mortality for severe pneumonia was 11.3%, as compared with 1.3% for nonsevere disease (p = 0.008). The ATS severity criteria are valid in HIV-infected patients with bacterial CAP. Our study provides the basis for identification of patients who may require hospitalization determined by clinical judgment and the five clinical criteria of shock, a CD4(+) cell count < 100/microl, pleural effusion, cavities, and multilobar involvement. These prognostic factors should be validated in independent cohort studies.

Clinical significance of polymicrobial versus monomicrobial bacteremia involving Pseudomonas aeruginosa

The objective of this study was to examine the clinical significance of polymicrobial bacteremia involving Pseudomonas aeruginosa. Two hundred forty-eight episodes of Pseudomonas aeruginosa bacteremia, 43 of which were polymicrobic, were studied prospectively over a 6-year period. Three sets of blood cultures were obtained for each patient. Positive results for all three blood cultures were found more frequently in patients with polymicrobial infection, who were older than those with monomicrobial infection. Patients with polymicrobial bacteremia also were worse clinically and developed shock more frequently. Crude mortality was higher in patients with polymicrobial infection. A multivariate analysis revealed three variables significantly and independently associated with polymicrobial Pseudomonas aeruginosa bacteremia: higher age, poor clinical status of the patient, and positive results for all blood cultures obtained.

Mycotic aneurysm of the aortic arch

A 61-year-old diabetic woman presented with a mycotic aneurysm of the aortic arch, also involving the left subclavian and vertebral arteries, caused by Staphylococcus aureus. Two months before, she had suffered from staphylococcal septic arthritis in her left knee. The patient was treated with antibiotics and an emergency operation was performed involving aneurysm excision and in situ synthetic graft replacement. She died on the fourth postoperative day from hemorrhagic shock.

Haemophilus influenzae pneumonia in human immunodeficiency virus-infected patients. The Grupo Andaluz para el Estudio de las Enfermedades Infecciosas

Although Haemophilus influenzae is a common etiologic agent of pneumonia in patients infected with human immunodeficiency virus (HIV), the characteristics of this pneumonia have not been adequately assessed. We have prospectively studied features of H. influenzae pneumonia in 26 consecutive HIV-infected inpatients. Most of these patients were severely immunosuppressed; 73.1% had a CD4+ cell count <100/microL. A subacute clinical presentation was observed in 27% of the patients and was associated with a higher degree of immunosuppression (P=.04). Bilateral lung infiltrates were noted radiographically in 57.7% of the cases. The mortality attributable to H. influenzae pneumonia was 11.5%. Thus, pneumonia caused by H. influenzae affects mainly patients with advanced HIV disease, and since its clinical and radiological features may be diverse, this etiology should be considered when pneumonia occurs in patients with advanced HIV infection. The mortality rate associated with H. influenzae pneumonia is not higher than that occurring in the general population.

Nontyphoidal salmonella intracranial infections in HIV-infected patients

Salmonella focal intracranial infections are unusual in human immunodeficiency virus (HIV)-infected patients. Six such infections have been reported in the world literature. We report a case of salmonella subdural and epidural cerebral empyema with concomitant osteomyelitis of the frontal bone. Such a complication in the course of salmonellosis is reported for the first time. In previously published case reports, four patients had brain abscess and two had subdural empyema. Salmonella typhimurium was isolated from two patients, and different serotypes were recovered from the others. All patients had advanced HIV disease, and all but two had had opportunistic infections before the diagnosis of salmonella intracranial infection. Surgical drainage combined with systemic antibiotic therapy resulted in the recovery of four of five patients. No regression of the lesions occurred in one patient treated only with antibiotics for multiple cerebral abscesses.

[Utility of bronchoalveolar lavage in the diagnosis of respiratory infection in HIV patients]

From January 1, 1992, to December 31, 1995, we studied 52 bronchoalveolar lavages in 45 HIV-infected patients. All patients with pulmonary symptoms and/or new pulmonary infiltrates underwent bronchoalveolar lavage (BAL) when the results of blood cultures and mycobacterial smears of sputum and urine were negative. Lavage fluid was investigated for the presence of P. carinii, bacteria, mycobacteria, fungi and virus. BAL was diagnostic in 39 (75%) cases. The organisms more frequently isolated were P. carinii and M. tuberculosis. Only one pathogen was identified in 28 cases (54%); two in ten (19%); and three in one patient (2%). BAL was, generally, well tolerated by the patient and had a high diagnostic yield in the evaluation of patients with HIV infection and respiratory symptoms.

Continuous infusion is superior to bolus doses with thoracic paravertebral blocks after thoracotomies

OBJECTIVES

This study was designed to determine whether a continuous thoracic paravertebral infusion of bupivacaine (continuous TPVI) offers a higher quality of analgesia than a bolus regimen after thoracotomy.

DESIGN

A prospective and randomized study.

SETTING

It was conducted by an anesthesiology and pain clinic department in a university hospital.

PARTICIPANTS

Thirty patients were included in this study.

INTERVENTIONS

As postoperative analgesia, the patients received either 20 mL of 0.375% bupivacaine every 6 hours (n = 15; bolus group), or a loading dose of 15 mL of 0.375% bupivacaine, plus an infusion of 5 mL of 0.25% bupivacaine every hour (n = 15; infusion group).

MEASUREMENTS AND MAIN RESULTS

Pain intensity was assessed at rest and on movement (coughing) at 0, 1, 4, 10, 20, and 48 hours by means of the visual analog scale. The need for additional rescue analgesia, bupivacaine plasma concentration in the infusion group, blockade level (pinprick), and vital signs were also recorded. There were no significant differences regarding the additional rescue analgesia, vital signs, and pinprick level. However, the pain scores were significantly higher in the bolus group at rest and on movement (p < 0.01). The bupivacaine plasma concentration was low with a Cmax of 1.841 +/- 0.20 micrograms/mL at 15 hours. No systemic toxicity or other side effects were seen.

CONCLUSION

Results suggest that continuous TPVI provides better pain control than the bolus regimen after this kind of surgery.

Mathematical analysis of epidural space location

BACKGROUND

The location of epidural space for local anaesthetic injection can be difficult. The aim of this study was to define the mathematical function of the pressure changes in the syringe during puncture of the epidural space. Knowledge of pressure changes might be of help to the anesthetist who attempts to ascertain the location of the needle, and it is essential to the design of a device with which to locate epidural space.

METHODS

Epidural punctures were performed in 20 patients, using an 18-Tuohy needle connected to a 10 ml syringe. The epidural space was located by the loss of resistance technique. Pressure variations within the injection system during epidural puncture were measured and digitized at 250 Hz. Pressure curves were analyzed for amplitude and rate of a decay after entry of the needle into the epidural space.

RESULTS

Pressure increased as the needle passed through skin, subcutaneous fat and muscle. The maximal pressure was observed when the needle perforated the ligamentum flavum (689 +/- 124 cm H2O). When the needle entered the epidural space, an exponential decrease in pressure was observed in all patients (R2 = 0.99; tau = 2.1 +/- 0.9 seconds). End-residual pressure was 22 +/- 12 cm H2O. The change in pressure observed when the needle entered the epidural space fitted a negative exponential function (y = e-x/2.08).

CONCLUSIONS

Pressures within the injection system for epidural puncture can reach 1100 cm H2O. Location of the epidural space is characterized by an exponential decay to and end-residual pressure below 50 cm H2O, with a constant time of approximately 2 seconds.