Effect of Analgesic Low-Dose Ketamine Infusions on the Cardiovascular Response: A Retrospective Analysis.

BACKGROUND: Low-dose ketamine infusion (LDKI) has shown effectiveness for treating acute pain associated with surgical and nonsurgical (traumatic, neuropathic, and acute cancer-related) origin as an adjuvant to opioids. The increasing use of LDKI as an opioid-sparing agent in multimodal analgesia requires a better understanding of its effects on the cardiovascular response, a known dose-dependent side effect of ketamine administration. We investigated the cardiovascular response of acute pain patients treated with LDKI. OBJECTIVES: The aim of the present study was to evaluate the effect of LDKI in hemodynamic variables (blood pressure [BP] and heart rate [HR]) during LDKI analgesia for up to 48 hours of treatment in an acute pain setting. Secondary objectives were to evaluate psychomimetic effects. STUDY DESIGN: Retrospective unicentric cohort design. SETTING: The study was conducted at an academic university hospital. METHODS: We conducted a single-center retrospective cohort analysis of adult patients who underwent LDKI to treat surgical and nonsurgical acute pain. We obtained data from the Hospital San Vicente Fundación Health Documentation System database and evaluated the medical records of 318 patients with surgical and nonsurgical pain. Patients received a 0.1 mg/kg/h ketamine infusion as part of a multimodal analgesic plan. Baseline systolic BP (SBP), diastolic BP (DBP), mean arterial pressure (MAP), and HR values were compared with those measured after 24 and 48 hours of treatment. Pain level and psychomimetic effects were measured at 24 and 48 hours. Cardiovascular complications and treatment duration were also recorded. Patients with a history of psychiatric, cardiovascular, or cognitive disease were excluded from the study. This study was registered in the clinicaltrials.gov database (identifier: NCT03979105). RESULTS: No statistical differences in SBP, DBP, MAP, or HR were observed when baseline and post-LDKI treatment values were compared (P < 0.05). When comparing hemodynamic variables after exposure to LDKI in patients with and without hypertension, we did not observe statistically significant differences in mean HR, systolic arterial pressure, diastolic arterial pressure, or MAP values at 24 and 48 hours. The frequency of severe pain was reduced from 72% on day 0 to 4.4% on day 1 and 6.2% on day 2 post-LDKI. Observed psychomimetic effects were confusion 4.39%, hallucinations 2.51%, and nightmares 1.25%. No major cardiovascular events were observed. LIMITATIONS: This study was limited by its retrospective design, the lack of a comparative matching cohort, and the good general condition of the majority of patients included in the study. CONCLUSIONS: LDKI (0.1 mg/kg/h) was not associated with significant changes in baseline BP or HR. Our results suggest that as an adjuvant in multimodal analgesia for surgical and nonsurgical acute pain, LDKI has a low impact on the cardiovascular response. KEY WORDS: Ketamine, adverse effects, tachycardia, hypertension, postoperative pain, chronic postsurgical pain.

Factors affecting populations of the endemic Iberian hare (Lepus granatensis) after the first myxomatosis outbreaks in Central Spain.

The Iberian hare (Lepus granatensis) is an endemic species distributed in Spain and Portugal. Myxomatosis outbreaks affecting this species were detected in 2018 in Central and Southern Spain, spreading afterward. Aiming to evaluate factors affecting the status of hare population after the arrival of myxomatosis, we conducted 108 nocturnal hare counts in Central Spain during two study periods (winter/spring and summer/autumn) in 54 different hunting grounds, covering 1071 km and observing 884 individuals. The mean density in winter/spring was 7.66 hares/100 ha, (range 6.14-9.54/100 ha), while in summer/autumn, it was 3.4 hares/100 ha (range 2.6-4.4/100 ha). Densities of hares were not affected by the dominant habitat and the presence/absence of myxomatosis outbreaks. Hares were more abundant at hunting grounds at a higher altitude and in those conducting targeted management, while detection of myxomatosis was related to lower altitude and higher levels of game management. A MaxEnt model used to generate a risk map for myxomatosis occurrence showed that the temperature annual range was the most important predictor, which suggests that environmental factors affecting myxomatosis vectors (mosquitoes, fleas, and ticks) could play a key role in disease transmission. As myxomatosis in hares is becoming endemic, hare densities may be improved by game management and the monitoring and surveillance of this emerging disease. These surveillance programs could be the basis of effective collaborations between hunters, researchers, and environmental managers.

The fractal dimension of a conspicuous ornament varies with mating status and shows assortative mating in wild red-legged partridges (Alectoris rufa).

Complex body designs, such as plumage ornaments in birds, can be described by fractal geometry. These complex patterns could have a role as visual signals during courtship and social interactions, but an empirical validation in the wild is currently lacking. Here, we investigated whether the fractal dimension (FD) of a complex plumage pattern displayed by red-legged partridges Alectoris rufa could function as a potential sexual signal. We captured wild birds early in the breeding season and tested if mated and unmated birds differed in the FD of their conspicuous melanin-based black bib. We also tested if the FD of the black bib was correlated within the pair, looking for evidence of assortative mating based on the expression of this trait. We simultaneously assessed similar effects in other ornamental traits (black bib size, white throat patch and black flank band surface, redness of the eye rings and bill). Mated birds showed higher black bib FD values than unmated ones. Mated males, but not females, also displayed a larger black bib. Moreover, the black bib FD (but not the trait size) and the white throat patch surface showed assortative mating. Finally, females with higher black bib FD showed smaller black flank band surface, suggesting a trade-off in the expression of the two melanin-pigmented plumage traits. This provides unique and novel indication for the shape complexity of a pigmented trait, here described by its fractal dimension, to be potentially under sexual selection in a wild animal.

Intraspecific and interspecific competition induces density-dependent habitat niche shifts in an endangered steppe bird.

Interspecific competition is a dominant force in animal communities that induces niche shifts in ecological and evolutionary time. If competition occurs, niche expansion can be expected when the competitor disappears because resources previously inaccessible due to competitive constraints can then be exploited (i.e., ecological release). Here, we aimed to determine the potential effects of interspecific competition between the little bustard (Tetrax tetrax) and the great bustard (Otis tarda) using a multidimensional niche approach with habitat distribution data. We explored whether the degree of niche overlap between the species was a density-dependent function of interspecific competition. We then looked for evidences of ecological release by comparing measures of niche breadth and position of the little bustard between allopatric and sympatric situations. Furthermore, we evaluated whether niche shifts could depend not only on the presence of great bustard but also on the density of little and great bustards. The habitat niches of these bustard species partially overlapped when co-occurring, but we found no relationship between degree of overlap and great bustard density. In the presence of the competitor, little bustard's niche was displaced toward increased use of the species' primary habitat. Little bustard's niche breadth decreased proportionally with great bustard density in sympatric sites, in consistence with theory. Overall, our results suggest that density-dependent variation in little bustard's niche is the outcome of interspecific competition with the great bustard. The use of computational tools like kernel density estimators to obtain multidimensional niches should bring novel insights on how species' ecological niches behave under the effects of interspecific competition in ecological communities.

Changes in behaviour and faecal glucocorticoid levels in response to increased human activities during weekends in the pin-tailed sandgrouse.

Human recreational activities are becoming increasingly widespread and frequent, a fact that may potentially exacerbate their effects on wildlife. These human-related disturbances on animals may induce behavioural and physiological changes that can ultimately affect their fitness, showing a similar anti-predator response that against natural predator or other threats. Here, we combine the use of behavioural and physiological approaches to assess the potential effect of winter human activities on a threatened farmland bird in Europe, the pin-tailed sandgrouse (Pterocles alchata). We compared before, during and after weekend variations in human activity rates, pin-tailed sandgrouse behaviour (flocking and flying behaviour, interspecific association in mixed flocks and habitat use) and faecal glucocorticoid metabolite concentrations. Human disturbances, in particular those associated with hunting activities, peaked during weekends. Sandgrouse showed significant behavioural changes (increased sandgrouse-only flock sizes, increased proportion of birds flying and changes in habitat use) during weekends and higher faecal glucocorticoid metabolite concentrations after the weekends compared with during or before weekends. Therefore, physiological stress levels could be modulated by behavioural adjustments such as increased flock sizes and changes in habitat use that may allow sandgrouse to cope with increased human disturbance rates during weekends. Nevertheless, temporal and spatial organization of hunting days among groups of estates might be good strategies to buffer these potential adverse effects on wintering pin-tailed sandgrouse and other steppe species of conservation concern, while preserving a socio-economically important activity such as hunting.

A resource-based modelling framework to assess habitat suitability for steppe birds in semiarid Mediterranean agricultural systems.

European agriculture is undergoing widespread changes that are likely to have profound impacts on farmland biodiversity. The development of tools that allow an assessment of the potential biodiversity effects of different land-use alternatives before changes occur is fundamental to guiding management decisions. In this study, we develop a resource-based model framework to estimate habitat suitability for target species, according to simple information on species' key resource requirements (diet, foraging habitat and nesting site), and examine whether it can be used to link land-use and local species' distribution. We take as a study case four steppe bird species in a lowland area of the north-eastern Iberian Peninsula. We also compare the performance of our resource-based approach to that obtained through habitat-based models relating species' occurrence and land-cover variables. Further, we use our resource-based approach to predict the effects that change in farming systems can have on farmland bird habitat suitability and compare these predictions with those obtained using the habitat-based models. Habitat suitability estimates generated by our resource-based models performed similarly (and better for one study species) than habitat based-models when predicting current species distribution. Moderate prediction success was achieved for three out of four species considered by resource-based models and for two of four by habitat-based models. Although, there is potential for improving the performance of resource-based models, they provide a structure for using available knowledge of the functional links between agricultural practices, provision of key resources and the response of organisms to predict potential effects of changing land-uses in a variety of context or the impacts of changes such as altered management practices that are not easily incorporated into habitat-based models.

Effect of Game Management on Wild Red-Legged Partridge Abundance.

The reduction of game and fish populations has increased investment in management practices. Hunting and fishing managers use several tools to maximize harvest. Managers need to know the impact their management has on wild populations. This issue is especially important to improve management efficacy and biodiversity conservation. We used questionnaires and field bird surveys in 48 hunting estates to assess whether red-legged partridge Alectoris rufa young/adult ratio and summer abundance were related to the intensity of management (provision of supplementary food and water, predator control and releases of farm-bred partridges), harvest intensity or habitat in Central Spain. We hypothesized that partridge abundance would be higher where management practices were applied more intensively. Variation in young/adult ratio among estates was best explained by habitat, year and some management practices. Density of feeders and water points had a positive relationship with this ratio, while the density of partridges released and magpies controlled were negatively related to it. The variables with greatest relative importance were feeders, releases and year. Variations in post-breeding red-legged partridge abundance among estates were best explained by habitat, year, the same management variables that influenced young/adult ratio, and harvest intensity. Harvest intensity was negatively related to partridge abundance. The other management variables had the same type of relationship with abundance as with young/adult ratio, except magpie control. Variables with greatest relative importance were habitat, feeders, water points, releases and harvest intensity. Our study suggests that management had an overall important effect on post-breeding partridge abundance. However, this effect varied among tools, as some had the desired effect (increase in partridge abundance), whereas others did not or even had a negative relationship (such as release of farm-reared birds) and can be thus considered inefficient or even detrimental. We advise reconsidering their use from both ecological and economical points of view.