Mechanisms to expedite pediatric clinical trial site activation: The DOSE trial experience

BACKGROUND

Timely trial start-up is a key determinant of trial success; however, delays during start-up are common and costly. Moreover, data on start-up metrics in pediatric clinical trials are sparse. To expedite trial start-up, the Trial Innovation Network piloted three novel mechanisms in the trial titled Dexmedetomidine Opioid Sparing Effect in Mechanically Ventilated Children (DOSE), a multi-site, randomized, double-blind, placebo-controlled trial in the pediatric intensive care setting.

METHODS

The three novel start-up mechanisms included: 1) competitive activation; 2) use of trial start-up experts, called site navigators; and 3) supplemental funds earned for achieving pre-determined milestones. After sites were activated, they received a web-based survey to report perceptions of the DOSE start-up process. In addition to perceptions, metrics analyzed included milestones met, time to start-up, and subsequent enrollment of subjects.

RESULTS

Twenty sites were selected for participation, with 19 sites being fully activated. Across activated sites, the median (quartile 1, quartile 3) time from receipt of regulatory documents to site activation was 82 days (68, 113). Sites reported that of the three novel mechanisms, the most motivating factor for expeditious activation was additional funding available for achieving start-up milestones, followed by site navigator assistance and then competitive site activation.

CONCLUSION

Study start-up is a critical time for the success of clinical trials, and innovative methods to minimize delays during start-up are needed. Milestone-based funds and site navigators were preferred mechanisms by sites participating in the DOSE study and may have contributed to the expeditious start-up timeline achieved.

CLINICALTRIALS

gov #: NCT03938857.

Nonadherence to appropriate tidal volume and PEEP in children with pARDS at a single center

BACKGROUND

Low tidal volume and adequate positive end-expiratory pressure (PEEP) are evidence-based approaches for pediatric acute respiratory distress syndrome (pARDS), however, data are limited regarding their use since pARDS guidelines were revised in 2015.

OBJECTIVE

To identify prevalence of, and factors associated with, nonadherence to appropriate tidal volume and PEEP in children with pARDS.

METHODS

Retrospective cohort study of children 1 month to <18 years with pARDS who received invasive mechanical ventilation from 2016 to 2018 in a single pediatric intensive care unit (PICU).

RESULTS

At 24 h after meeting pARDS criteria, 48/86 (56%) patients received tidal volume ≤8 ml/kg of ideal body weight and 45/86 (52%) received appropriate PEEP, with 22/86 (26%) receiving both. Among patients ≥2 years of age, a lower proportion of patients with overweight/obesity (9/25, 36%) had appropriate tidal volume versus those in the normal or underweight category (16/22, 73%, p = 0.02). When FIO2 was ≥50%, PEEP was appropriate in 19/60 (32%) cases versus 26/26 (100%) with FIO2  < 50% (p < 0.0001). pARDS was documented in the progress note in 7/86 (8%) patients at 24 h. Severity of pARDS, documentation in the progress note, and other clinical factors were not significantly associated with use of appropriate tidal volume and PEEP, however pARDS was documented more commonly in patients with severe pARDS.

CONCLUSIONS

In a single PICU in the United States, children with pARDS did not receive appropriate tidal volume for ideal body weight nor PEEP. Targets for improving tidal volume and PEEP adherence may include overweight patients and those receiving FIO2  ≥ 50%, respectively.

Eutectic Mixture of Lidocaine and Prilocaine Decreases Movement and Propofol Requirements for Pediatric Lumbar Puncture During Deep Sedation: A Randomized, Placebo-Controlled, Double Blind Trial

Deep sedation/general anesthesia is commonly used in pediatric oncology patients undergoing lumbar puncture (LP). Propofol is often used for sedation, with or without a narcotic. We hypothesized that eutectic mixture of lidocaine and prilocaine (EMLA) would allow for lower cumulative doses of propofol and less movement. We performed a prospective, randomized, double blind, placebo-controlled trial in children undergoing sedation for LP. Standard initial weight-based doses of propofol and fentanyl were administered, with either EMLA cream or a placebo cream applied topically. The primary outcome was the total dose of propofol administered to each patient. We also tracked patient movement and complications. Twenty-seven patients underwent 152 LPs. Patients randomized to EMLA cream (n=75) were significantly more likely to receive a lower dose of propofol (2.94 mg/kg, SE=0.25, vs. 3.22 mg/kg, SE=0.19; P=0.036) and to not require additional propofol doses (probability 0.49, SE=0.08 vs. 0.69, SE=0.06; P=0.001) compared with patients randomized to placebo cream (n=77). In addition, patients with EMLA cream were significantly less likely to demonstrate minor or major movement. EMLA cream results in less movement and less propofol administration in pediatric oncology patients undergoing sedation for LP.

A Framework for Pediatric Intensivists Providing Compassionate Extubation at Home

For families facing end-of-life decisions for their critically ill children, compassionate extubation at home is a valuable service that pediatric intensivists can provide. Compassionate extubation at home is resource intensive and can be logistically challenging. Discouragingly, guidance on compassionate extubation at home in the literature is limited. We developed an evidence- and experience-based framework for compassionate extubation at home addressing common planning challenges and resource management. Our objective is to share this framework and an accompanying checklist, so that pediatric intensivists in other institutions can adapt these tools for their use, reducing barriers to providing compassionate extubation at home for critically ill children at the end of life.

Handling, infectious agents and physiological condition influence survival and post-release behaviour in migratory adult coho salmon after experimental displacement

For Pacific salmon captured and released by fisheries, post-release behaviour and survival may be influenced by their health and condition at time of capture. We sought to characterize the interactions between infectious agent burden, fish immune and stress physiology and fisheries stressors to investigate the potential for capture-mediated pathogen-induced mortality in adult coho salmon Oncorhynchus kisutch. We used radio-telemetry paired with high-throughput qPCR of non-lethal gill biopsies for infectious agents and host biomarkers from 200 tagged fish experimentally displaced and exposed to various experimental fisheries treatments (gill net entanglement, recreational angling and recreational angling with air exposure vs. non-sampled control). We characterized relationships among post-release behaviour and survival, infectious agent presence and loads, physiological parameters and transcription profiles of stress and immune genes. All infectious agents detected were endemic and in loads consistent with previous adult Pacific salmon monitoring. Individuals exposed to fisheries treatments were less likely to reach spawning habitat compared to controls, and handling duration independent of fisheries gear had a negative effect on survival. High infectious agent burden was associated with accelerated migration initiation post-release, revealing behavioural plasticity in response to deteriorating condition in this semelparous species. Prevalence and load of infectious agents increased post-migration as well as transcription signatures reflected changes in immune and stress profiles consistent with senescence. Results from this study further our understanding of factors associated with fisheries that increase risk of post-release mortality and characterize some physiological mechanisms that underpin migratory behaviour.

A survey of microparasites present in adult migrating Chinook salmon (Oncorhynchus tshawytscha) in south-western British Columbia determined by high-throughput quantitative polymerase chain reaction

Microparasites play an important role in the demography, ecology and evolution of Pacific salmonids. As salmon stocks continue to decline and the impacts of global climate change on fish populations become apparent, a greater understanding of microparasites in wild salmon populations is warranted. We used high-throughput, quantitative PCR (HT-qRT-PCR) to rapidly screen 82 adult Chinook salmon from five geographically or genetically distinct groups (mostly returning to tributaries of the Fraser River) for 45 microparasite taxa. We detected 20 microparasite species, four of which have not previously been documented in Chinook salmon, and four of which have not been previously detected in any salmonids in the Fraser River. Comparisons of microparasite load to blood plasma variables revealed some positive associations between Flavobacterium psychrophilum, Cryptobia salmositica and Ceratonova shasta and physiological indices suggestive of morbidity. We include a comparison of our findings for each microparasite taxa with previous knowledge of its distribution in British Columbia.

Setting positive end-expiratory pressure during jet ventilation to replicate the mean airway pressure of oscillatory ventilation

BACKGROUND

High-frequency ventilation can be delivered with either oscillatory ventilation (HFOV) or jet ventilation (HFJV). Traditional clinician biases may limit the range of function of these important ventilation modes. We hypothesized that (1) the jet ventilator can be an accurate monitor of mean airway pressure (P (aw)) during HFOV, and (2) a mathematical relationship can be used to determine the positive end-expiratory pressure (PEEP) setting required for HFJV to reproduce the P (aw) of HFOV.

METHODS

In phase 1 of our experiment, we used a differential pressure pneumotachometer and a jet adapter in-line between an oscillator circuit and a pediatric lung model to measure P (aw), PEEP, and peak inspiratory pressure (PIP). Thirty-six HFOV setting combinations were studied, in random order. We analyzed the correlation between the pneumotachometer and HFJV measurements. In phase 2 we used the jet as the monitoring device during each of the same 36 combinations of HFOV settings, and recorded P (aw), PIP, and DeltaP. Then, for each combination of settings, the jet ventilator was placed in-line with a conventional ventilator and was set at the same rate and PIP as was monitored during HFOV. To determine the appropriate PEEP setting, we calculated the P (aw) contributed by the PIP, respiratory rate, and inspiratory time set for HFJV, and subtracted this from the goal P (aw). This value was the PEEP predicted for HFJV to match the HFOV P (aw).

RESULTS

The correlation coefficient between the pneumotachometer and HFJV measurements was r = 0.99 (mean difference 0.62 +/- 0.30 cm H(2)O, p < 0.001). The predicted and actual PEEP required were highly correlated (r = 0.99, p < 0.001). The mean difference in these values is not statistically significantly different from zero (mean difference 0.25 +/- 1.02 cm H(2)O, p > 0.15).

CONCLUSIONS

HFJV is an accurate monitor during HFOV. These measurements can be used to calculate the predicted PEEP necessary to match P (aw) on the 2 ventilators. Replicating the P (aw) with adequate PEEP on HFJV may help simplify transitioning between ventilators when clinically indicated.

Mixed-stock analysis reveals the migrations of juvenile hawksbill turtles (Eretmochelys imbricata) in the Caribbean Sea

Hawksbill turtles (Eretmochelys imbricata) migrate between nesting beaches and feeding habitats that are often associated with tropical reefs, but it is uncertain which nesting colonies supply which feeding habitats. To address this gap in hawksbill biology, we compile previously published and new mitochondrial DNA (mtDNA) haplotype data for 10 nesting colonies (N = 347) in the western Atlantic and compare these profiles to four feeding populations and four previously published feeding samples (N = 626). Nesting colonies differ significantly in mtDNA haplotype frequencies (Phi(ST) = 0.588, P < 0.001), corroborating earlier conclusions of nesting site fidelity and setting the stage for mixed-stock analysis. Feeding aggregations show lower but significant structure (Phi(ST) = 0.089, P < 0.001), indicating that foraging populations are not homogenous across the Caribbean Sea. Bayesian mixed-stock estimates of the origins of juveniles in foraging areas show a highly significant, but shallow, correlation with nesting population size (r = 0.378, P = 0.004), supporting the premise that larger rookeries contribute more juveniles to feeding areas. A significant correlation between the estimated contribution and geographical distance from nesting areas (r = -0.394, P = 0.003) demonstrates the influence of proximity on recruitment to feeding areas. The influence of oceanic currents is illustrated by pelagic stage juveniles stranded in Texas, which are assigned primarily (93%) to the upstream rookery in Yucatan. One juvenile had a haplotype previously identified only in the eastern Atlantic, invoking rare trans-oceanic migrations. The mixed-stock analysis demonstrates that harvests in feeding habitats will impact nesting colonies throughout the region, with the greatest detriment to nearby nesting populations.

Conservation implications of complex population structure: lessons from the loggerhead turtle (Caretta caretta)

Complex population structure can result from either sex-biased gene flow or population overlap during migrations. Loggerhead turtles (Caretta caretta) have both traits, providing an instructive case history for wildlife management. Based on surveys of maternally inherited mtDNA, pelagic post-hatchlings show no population structure across the northern Atlantic (phi(ST) < 0.001, P = 0.919), subadults in coastal habitat show low structure among locations (phi(ST) = 0.01, P < 0.005), and nesting colonies along the southeastern coast of the United States have strong structure (phi(ST) = 0.42, P < 0.001). Thus the level of population structure increases through progressive life history stages. In contrast, a survey of biparentally inherited microsatellite DNA shows no significant population structure: R(ST) < 0.001; F(ST) = 0.002 (P > 0.05) across the same nesting colonies. These results indicate that loggerhead females home faithfully to their natal nesting colony, but males provide an avenue of gene flow between regional nesting colonies, probably via opportunistic mating in migratory corridors. As a result, all breeding populations in the southeastern United States have similar levels of microsatellite diversity (H(E) = 0.70-0.89), whereas mtDNA haplotype diversity varies dramatically (h = 0.00-0.66). Under a conventional interpretation of the nuclear DNA data, the entire southeastern United States would be regarded as a single management unit, yet the mtDNA data indicate multiple isolated populations. This complex population structure mandates a different management strategy at each life stage. Perturbations to pelagic juveniles will have a diffuse impact on Atlantic nesting colonies, mortality of subadults will have a more focused impact on nearby breeding populations, and disturbances to adults will have pinpoint impact on corresponding breeding populations. These findings demonstrate that surveys of multiple life stages are desirable to resolve management units in migratory marine species.

Phylogeography of the trumpetfishes (Aulostomus): ring species complex on a global scale

The distribution of circumtropical marine species is limited by continental boundaries, cold temperate conditions, and oceanic expanses, but some of these barriers are permeable over evolutionary time scales. Sister taxa that evolved in separate ocean basins can come back into contact, and the consequences of this renewed sympatry may be a key to understanding evolutionary processes in marine organisms. The circumtropical trumpetfishes (Aulostomus) include a West Atlantic species (A. maculatus), an Indian-Pacific species (A. chinensis), and an East Atlantic species (A. strigosus) that may be the product of a recent invasion from the Indian Ocean. To resolve patterns of divergence and speciation, we surveyed 480 bp of mitochondrial DNA cytochrome b in 196 individuals from 16 locations. Based on a conventional molecular clock of 2% sequence divergence per million years, the deepest partitions in a neighbor-joining tree (d = 0.063-0.082) are consistent with separation of West Atlantic and Indian-Pacific species by the Isthmus of Panama, 3-4 million years ago. By the same criteria, trumpetfish in the East Atlantic were isolated from the Indian Ocean about 2.5 million years ago (d = 0.044-0.054), coincident with the advent of glacial cycles and cold-water upwelling around South Africa. Continental barriers between tropical oceans have only rarely been surmounted by trumpetfishes, but oceanic barriers do not appear to be substantial, as indicated by weak population partitioning (phiST = 0.093) in A. chinensis across the Indian and Pacific Oceans. Finally, morphological and mitochondrial DNA data indicate hybridization of A. strigosus and A. maculatus in Brazil. After 3-4 million years and a globe-spanning series of vicariant and dispersal events, trumpetfish lineages have come back into contact in the southwest Atlantic and appear to be merging. This ring species phenomenon may occur in a broad array of marine organisms, with clear implications for the production and maintenance of biodiversity in marine ecosystems.

Molecular phylogeny and biogeography of the marine shrimp Penaeus

The evolutionary relationships among 13 species representing all six subgenera of the shrimp genus Penaeus were examined using 558 bp of mitochondrial (mt) DNA from the cytochrome oxidase subunit I gene. Analyses of this sequence revealed high genetic divergence between species (d = 8-24%), a finding which contrasts with previous work, which indicated that genetic diversity, based on electrophoretic analysis of allozymes, was extremely low in Penaeus. Three tree-building methods (maximum parsimony, neighbor joining, and maximum likelihood) were concordant in indicating that current subgenera assignments do not reflect evolutionary partitions within the genus Penaeus. While the molecular phylogenies cast doubt on the validity of subgenera, the observed relationships are concordant with biogeographic boundaries across the tropical range of Penaeus. Both the western Atlantic and eastern Pacific contain monophyletic species pairs which cluster together in all analyses. The Indo-Pacific contains a putative basal taxa (P. indicus), the deepest mtDNA lineages, and the highest diversity, including representatives of all three primary lineages observed in Penaeus. These data are consistent with the suggestion by Dall et al. (1990) that Penaeus arose in the Indo-Pacific and radiated eastward and westward to account for the current circumtropical distribution of the genus. This phylogenetic framework for Penaeus will enhance the scientific foundations for wildlife resource management and breeding experiments (hybridization and related manipulations) designed to improve the commercial value of captive strains.

Testing models of female reproductive migratory behaviour and population structure in the Caribbean hawksbill turtle, Eretmochelys imbricata, with mtDNA sequences

Information on the reproductive behaviour and population structure of female hawksbill turtles, Eretmochelys imbricata, is necessary to define conservation priorities for this highly endangered species. Two hypotheses to explain female nest site choice, natal homing and social facilitation, were tested by analyzing mtDNA control region sequences of 103 individuals from seven nesting colonies in the Caribbean and western Atlantic. Under the social facilitation model, newly mature females follow older females to a nesting location, and subsequently use this site for future nesting. This model generates an expectation that female lineages will be homogenized among regional nesting colonies. Contrary to expectations of the social facilitation model, mtDNA lineages were highly structured among western Atlantic nesting colonies. These analyses identified at least 6 female breeding stocks in the Caribbean and western Atlantic and support a natal homing model for recruitment of breeding females. Reproductive populations are effectively isolated over ecological time scales, and recovery plans for this species should include protection at the level of individual nesting colonies.