Direct observation of the two-plasmon-decay common plasma wave using ultraviolet Thomson scattering

A 263-nm Thomson-scattering beam was used to directly probe two-plasmon-decay (TPD) excited electron plasma waves (EPWs) driven by between two and five 351-nm beams on the OMEGA Laser System. The amplitude of these waves was nearly independent of the number of drive beams at constant overlapped intensity, showing that the observed EPWs are common to the multiple beams. In an experimental configuration where the Thomson-scattering diagnostic was not wave matched to the common TPD EPWs, a broad spectrum of TPD-driven EPWs was observed, indicative of nonlinear effects associated with TPD saturation. Electron plasma waves corresponding to Langmuir decay of TPD EPWs were observed in both Thomson-scattering spectra, suggesting the Langmuir decay instability as a TPD saturation mechanism. Simulated Thomson-scattering spectra from three-dimensional numerical solutions of the extended Zakharov equations of TPD are in excellent agreement with the experimental spectra and verify the presence of the Langmuir decay instability.

Continuous regional anaesthesia provides effective pain management and reduces opioid requirement following major lower limb amputation

OBJECTIVES

Postoperative stump pain after major lower limb amputation is a significant impediment to the recovery of amputees. The vast majority of patients require opioid analgesics following surgery, which are associated with opioid-related side-effects. Here, we investigate whether intraoperative placement of a peripheral nerve stump catheter followed by continuous infusion of local anesthetic is as effective at pain control as current analgesic practices. If beneficial, this procedure could potentially reduce post-amputation opioid consumption and opioid-related adverse effects.

METHODS

A retrospective chart review was conducted of 198 patients over a 4-year period who had undergone a major lower limb amputation for indications related to peripheral vascular disease. Postoperatively, 102 patients received a perineural catheter were compared to 96 patients who did not. The primary outcomes of this study were the amount of morphine equivalents used in the first 72 hours postoperatively and postoperative pain intensity in the first 24 hours.

RESULTS

A total of 198 lower-limb amputations were selected for analyses. Multiple regression analyses indicated that perineural catheter use was associated with a lower cumulative postoperative opioid consumption over the first 72 hours but not postoperative pain scores at 24 hours. Perineural catheter use led to a 40% reduction in opioid use during the first 72 hours postoperatively. Mixed model repeated measures analysis demonstrated that this opioid reduction was consistent over time. Other variables related to total opioid use included age, pre-surgical chronic pain, pre-surgical opioid use, patient-controlled analgesia.

CONCLUSIONS

Continuous perineural infusions of local anesthetic are a safe and effective method for reducing post-amputation opioid analgesic medications after major lower limp amputation.

Nonuniformly driven two-plasmon-decay instability in direct-drive implosions

Half-harmonic emission spectra and images taken during directly driven implosions show that the two-plasmon decay (TPD) instability is driven nonuniformly over the target surface and that multibeam effects dominate this instability. The images show a spatially limited extent of the TPD instability. A prominent spectral feature is used to determine the electron temperature in the corona. Near threshold the temperatures agree with one-dimensional hydrodynamic predictions but exceed them by ∼10% above the TPD threshold. Two-dimensional hydrodynamic simulations indicate that a significant part (∼20%) of the laser intensity must be locally absorbed by the TPD instability (i.e., by collisional damping of the electron plasma waves) to maintain these temperature islands.

Effect of total-body prehabilitation on postoperative outcomes: a systematic review and meta-analysis

OBJECTIVE

To systematically review the evidence of pre-operative exercise, known as 'prehabilitation', on peri- and postoperative outcomes in adult surgical populations.

DESIGN

Systematic review and meta-analysis.

DATA SOURCES

CENTRAL, Medline, EMBASE, CINAHL, PsycINFO and PEDro were searched from 1950 to 2011.

METHODS

Two reviewers independently examined relevant, English-language articles that examined the effects of pre-operative total-body exercise with peri- and postoperative outcome analysis. Given the nascence of this field, controlled and uncontrolled trials were included. Risk of bias was assessed using the Cochrane Risk of Bias Assessment tool. Only data on length of stay were considered eligible for meta-analysis due to the heterogeneity of measures and methodologies for assessing other outcomes.

RESULTS

In total, 4597 citations were identified by the search strategy, of which 21 studies were included. Trials were generally small (median=54 participants) and of moderate to poor methodological quality. Compared with standard care, the majority of studies found that total-body prehabilitation improved postoperative pain, length of stay and physical function, but it was not consistently effective in improving health-related quality of life or aerobic fitness in the studies that examined these outcomes. The meta-analysis indicated that prehabilitation reduced postoperative length of stay with a small to moderate effect size (Hedges' g=-0.39, P=0.033). Intervention-related adverse events were reported in two of 669 exercising participants.

CONCLUSION

The literature provides early evidence that prehabilitation may reduce length of stay and possibly provide postoperative physical benefits. Cautious interpretation of these findings is warranted given modest methodological quality and significant risk of bias.

Peripheral blood stem-cell harvest using percutaneous arterial lines in children

BACKGROUND

Autologous peripheral blood stem-cell collection (PBSCC) in children has become an integral part of contemporary treatment protocols, but the procedure is often complicated due to technical issues related to vascular access. Central line placement is often implemented to surmount this problem, but is associated with complications such as bleeding, thrombosis and pneumothorax. As an alternative we have introduced the use of radial arterial lines for PBSCC in children.

PROCEDURE

Data from autologous stem cell collections performed from October 2002 to December 2011 using a radial arterial line were collected.

RESULTS

A total of 372 PBSCC procedures were performed during the study period; an arterial line was used in 311 PBSCC's in 208 children. The average patient age and weight were 7.9 years (SD 5.4) and 28.3 kg (SD 20.4), respectively. The smallest patient was 9 months old and weighed 7 kg. The mean total volume processed was 8,593 cm(3) (SD 4,854), and the mean number of blood volumes processed was 4.3. Mean collection time for a single blood volume was 55 minutes (SD 15.5). The mean number of CD34+ cells collected per donation was 5.8 × 10(6) /kg. Ninety-seven patients (46%) required more than one collection to meet the requested CD34+ cell target. No serious adverse effects associated with vascular access occurred in this cohort.

CONCLUSION

Percutaneous placement of radial artery catheters can be rapidly and safely performed in very small infants and in children with difficult venous access. This technique provides a reliable platform for efficient PBSCC.

The magnetic recoil spectrometer for measurements of the absolute neutron spectrum at OMEGA and the NIF

The neutron spectrum produced by deuterium-tritium (DT) inertial confinement fusion implosions contains a wealth of information about implosion performance including the DT yield, ion-temperature, and areal-density. The Magnetic Recoil Spectrometer (MRS) has been used at both the OMEGA laser facility and the National Ignition Facility (NIF) to measure the absolute neutron spectrum from 3 to 30 MeV at OMEGA and 3 to 36 MeV at the NIF. These measurements have been used to diagnose the performance of cryogenic target implosions to unprecedented accuracy. Interpretation of MRS data requires a detailed understanding of the MRS response and background. This paper describes ab initio characterization of the system involving Monte Carlo simulations of the MRS response in addition to the commission experiments for in situ calibration of the systems on OMEGA and the NIF.

A reflective optical transport system for ultraviolet Thomson scattering from electron plasma waves on OMEGA

A reflective optical transport system has been designed for the OMEGA Thomson-scattering diagnostic. A Schwarzschild objective that uses two concentric spherical mirrors coupled to a Pfund objective provides diffraction-limited imaging across all reflected wavelengths. This enables the operator to perform Thomson-scattering measurements of ultraviolet (0.263 μm) light scattered from electron plasma waves.

Measuring the absolute deuterium-tritium neutron yield using the magnetic recoil spectrometer at OMEGA and the NIF

A magnetic recoil spectrometer (MRS) has been installed and extensively used on OMEGA and the National Ignition Facility (NIF) for measurements of the absolute neutron spectrum from inertial confinement fusion implosions. From the neutron spectrum measured with the MRS, many critical implosion parameters are determined including the primary DT neutron yield, the ion temperature, and the down-scattered neutron yield. As the MRS detection efficiency is determined from first principles, the absolute DT neutron yield is obtained without cross-calibration to other techniques. The MRS primary DT neutron measurements at OMEGA and the NIF are shown to be in excellent agreement with previously established yield diagnostics on OMEGA, and with the newly commissioned nuclear activation diagnostics on the NIF.

MRI characterization and longitudinal study of focal cerebellar lesions in a young tuberous sclerosis cohort

BACKGROUND AND PURPOSE

There are few articles characterizing cerebellar lesions in patients with TSC and no published series documenting longitudinal evaluation of these lesions, to our knowledge. Recent suggestion of a correlation between autism and cerebellar lesions in patients with TSC heightens the importance of understanding these lesions. Our purpose was to characterize cerebellar lesions in a cohort of young patients with TSC with specific interest in assessing longitudinal changes.

MATERIALS AND METHODS

We retrospectively reviewed MR images from 145 pediatric and young adult patients with tuberous sclerosis (mean age, 7.6 years). A number of imaging characteristics of cerebellar tubers were recorded, and patients were evaluated for SGAs. Patients with follow-up scans >3 months from the original scan were further analyzed for longitudinal tuber characterization.

RESULTS

There were 24.1% of patients with focal cerebellar lesions; 52.4% of patients with cerebellar lesions demonstrated change in imaging characteristics during longitudinal analysis. Fifty-one percent of the lesions were enhanced after gadolinium administration. Twenty percent of the patients with cerebellar lesions had pathologically confirmed SGAs compared with the incidence of 11% in the 145 patients with TSC reviewed.

CONCLUSIONS

In our large cohort of young patients with TSC, cerebellar tubers were common and 52% of patients had tubers that changed with time. A higher percentage of patients with cerebellar lesions developed SGAs than patients with TSC without cerebellar lesions. Because this is the first reported longitudinal study of cerebellar lesions in TSC, further investigation may provide additional insight into TSC pathology and associated clinical manifestations, such as autism, developmental delay, and seizures.

Spinal anesthesia for noncardiac surgery in infants with congenital heart diseases

OBJECTIVE/AIM

To compare hemodynamic parameters in infants with congenital heart disease (CHD) undergoing noncardiac surgery (NCS) under awake spinal anesthesia (SA) with controls without CHD also undergoing SA.

BACKGROUND

NCS poses a twofold higher mortality risk in infants with CHD. SA might be a good alternative to general anesthesia (GA) in this setting.

METHODS

The files of 84 infants were reviewed; 42 had CHD and 42 were controls without CHD. Primary outcome measures were percent decrease in mean arterial pressure (%MAP decrease) and heart rate (%HR decrease)from baseline to the lowest intraoperative value. One-way analysis of variance(ANOVA), ANOVA with repeated measures, Pearson chi-square test, Fisher's exact test, and Pearson correlation were used for statistical analysis.Time to discharge was analyzed with the nonparametric Mann–Whitney U-test.

RESULTS

There were no significant between-group differences in %MAP decrease and %HR decrease; no significant associations and correlations between %MAP decrease or %HR decrease and other variables; and no correlation between %MAP decrease and %HR decrease. A %MAP decrease of >20% was documented in 11 patients with CHD (26.2%) and 10 controls (23.8%); a lowest intraoperative HR of <100 b.min)1 was recorded in two study patients (4.8%) and four controls (9.5%) (P = NS for both). There were no cases of high SA or conversion to GA and no need for mechanical ventilation or inotropic support intra/postoperatively.

CONCLUSIONS

These preliminary findings show that hemodynamic parameters in infants with CHD undergoing NCS under awake SA are not different from controls without CHD and that SA appears to be safe in infants with CHD.

The association of preterm birth and small birthweight for gestational age on childhood disability screening using the Ten Questions Plus tool in rural Sarlahi district, southern Nepal

CONTEXT

The Ten Questions tool was developed in 1984 as a low-cost, simple screen for childhood disability and referral for diagnosis in low-resource settings, and its use in Nepal has not been previously evaluated. Preterm birth and intrauterine growth restriction are potential risk factors for child disability and loss of developmental potential, but there are few studies examining this relationship from developing settings.

OBJECTIVE

  To examine the associations of small for gestational age and preterm birth as predictors of Ten Questions Plus positivity.

DESIGN, SETTING AND PARTICIPANTS

The Ten Questions Plus questionnaire was administered to caregivers of 680 children between 2 and 5 years of age from August 2007 to March 2008 in rural Sarlahi, southern Nepal. Participants had previously been enrolled in a randomized trial of chlorhexidine cleansing at birth. At 1 month of age, children were then enrolled into a randomized 2 × 2 factorial trial of daily iron and zinc supplementation between October 2001 and January 2006.

INTERVENTION

None.

MAIN OUTCOME MEASURE

Positive screen on the Ten Questions Plus tool defined as a positive response to one or more questions.

RESULTS

Of preterm children, 37 (33.6%) had a positive response to at least one question on the Ten Questions Plus and were considered at risk for disability. One hundred and seventy term children (29.8%) were at risk for disability.

CONCLUSIONS

The Ten Questions Plus tool can be used in this rural Nepali setting to identify children at increased risk for mental and physical disability to be targeted for further examination. The prevalence of parent-reported disabilities is high in this population (almost one-third of children); children who are both preterm and small-for-gestational age are at increased risk for motor milestone delay, reported learning difficulty, speech and behavioural problems. Intrauterine growth restriction may affect child development and result in disabilities later in childhood.

Persistent orofacial muscle pain

The pathophysiology of persistent orofacial myalgia has been the centre of much controversy. In this article we suggest a novel descriptive term; 'persistent orofacial muscle pain' (POMP) and review current evidence that supports the hypothesis that the induction of POMP involves the interplay between a peripheral nociceptive source in muscle, a faulty central nervous system component and decreased coping ability. In this context it is widely accepted that a complex interaction of variable intrinsic and extrinsic factors act to induce POMP and dysfunction.

Supplementation with vitamin A early in life and subsequent risk of asthma

Animal models suggest that vitamin A deficiency affects lung development adversely and promotes airway hyperresponsiveness, and may predispose to an increased risk of asthma. We examined the long-term effects of vitamin A supplementation early in life on later asthma risk. In 2006-2008, we revisited participants from two cohorts in rural Nepal who were enrolled in randomised trials of vitamin A supplementation. The first cohort received vitamin A or placebo for <16 months during their pre-school years (1989-1991). The second cohort was born to mothers who received vitamin A, β-carotene or placebo before, during and after pregnancy (1994-1997). At follow-up, we asked about asthma symptoms and performed spirometry. Out of 6,421 subjects eligible to participate, 5,430 (85%) responded to our respiratory survey. Wheezing prevalence during the previous year was 4.8% in participants aged 9-13 yrs and 6.6% in participants aged 14-23 yrs. We found no differences between the vitamin A supplemented and placebo groups from either trial in the prevalence of lifetime or current asthma and wheeze or in spirometric indices of obstruction (p ≥ 0.12 for all comparisons). Vitamin A supplementation early in life was not associated with a decreased risk of asthma in an area with chronic vitamin A deficiency.

Breast-feeding initiation time and neonatal mortality risk among newborns in South India

OBJECTIVE

To examine the association between breast-feeding initiation time and neonatal mortality in India, where breast-feeding initiation varies widely from region to region.

STUDY DESIGN

Data were collected as part of a community-based, randomized, placebo-controlled trial of the impact of vitamin A supplementation in rural villages of Tamil Nadu, India. Multivariate binomial regression analysis was used to estimate the association between neonatal mortality and breast-feeding initiation time (<12 h, 12 to 24 h, >24 h) among infants surviving a minimum of 48 h.

RESULT

Among 10 464 newborns, 82.1% were first breast-fed before 12 h, 13.8% were breast-fed between 12 and 24 h, and 4.1% were breast-fed after 24 h. After adjusting for birth weight, gestational age and other covariates, late initiators (>24 h) were at ∼78% higher risk of death (relative risk=1.78 (95% confidence interval (CI)=1.03 to 3.10)). There was no difference in mortality risk when comparing babies fed in the first 12 h compared with the second 1  h after birth.

CONCLUSION

Late (>24 h) initiation of breast-feeding is associated with a higher risk of neonatal mortality in Tamil Nadu. Emphasis on breast-feeding promotion programs in low-resource settings of India where early initiation is low could significantly reduce neonatal mortality.