Bubbles in live-stranded dolphins

Bubbles in supersaturated tissues and blood occur in beaked whales stranded near sonar exercises, and post-mortem in dolphins bycaught at depth and then hauled to the surface. To evaluate live dolphins for bubbles, liver, kidneys, eyes and blubber-muscle interface of live-stranded and capture-release dolphins were scanned with B-mode ultrasound. Gas was identified in kidneys of 21 of 22 live-stranded dolphins and in the hepatic portal vasculature of 2 of 22. Nine then died or were euthanized and bubble presence corroborated by computer tomography and necropsy, 13 were released of which all but two did not re-strand. Bubbles were not detected in 20 live wild dolphins examined during health assessments in shallow water. Off-gassing of supersaturated blood and tissues was the most probable origin for the gas bubbles. In contrast to marine mammals repeatedly diving in the wild, stranded animals are unable to recompress by diving, and thus may retain bubbles. Since the majority of beached dolphins released did not re-strand it also suggests that minor bubble formation is tolerated and will not lead to clinically significant decompression sickness.     

Deadly diving? Physiological and behavioural management of decompression stress in diving mammals

Decompression sickness (DCS; 'the bends') is a disease associated with gas uptake at pressure. The basic pathology and cause are relatively well known to human divers. Breath-hold diving marine mammals were thought to be relatively immune to DCS owing to multiple anatomical, physiological and behavioural adaptations that reduce nitrogen gas (N(2)) loading during dives. However, recent observations have shown that gas bubbles may form and tissue injury may occur in marine mammals under certain circumstances. Gas kinetic models based on measured time-depth profiles further suggest the potential occurrence of high blood and tissue N(2) tensions. We review evidence for gas-bubble incidence in marine mammal tissues and discuss the theory behind gas loading and bubble formation. We suggest that diving mammals vary their physiological responses according to multiple stressors, and that the perspective on marine mammal diving physiology should change from simply minimizing N(2) loading to management of the N(2) load. This suggests several avenues for further study, ranging from the effects of gas bubbles at molecular, cellular and organ function levels, to comparative studies relating the presence/absence of gas bubbles to diving behaviour. Technological advances in imaging and remote instrumentation are likely to advance this field in coming years.     

Ontogeny of diving behaviour in the Australian sea lion: trials of adolescence in a late bloomer

1. Foraging behaviours of the Australian sea lion (Neophoca cinerea) reflect an animal working hard to exploit benthic habitats. Lactating females demonstrate almost continuous diving, maximize bottom time, exhibit elevated field metabolism and frequently exceed their calculated aerobic dive limit. Given that larger animals have disproportionately greater diving capabilities, we wanted to examine how pups and juveniles forage successfully. 2. Time/depth recorders were deployed on pups, juveniles and adult females at Seal Bay Conservation Park, Kangaroo Island, South Australia. Ten different mother/pup pairs were equipped at three stages of development (6, 15 and 23 months) to record the diving behaviours of 51 (nine instruments failed) animals. 3. Dive depth and duration increased with age. However, development was slow. At 6 months, pups demonstrated minimal diving activity and the mean depth for 23-month-old juveniles was only 44 +/- 4 m, or 62% of adult mean depth. 4. Although pups and juveniles did not reach adult depths or durations, dive records for young sea lions indicate benthic diving with mean bottom times (2.0 +/- 0.2 min) similar to those of females (2.1 +/- 0.2 min). This was accomplished by spending higher proportions of each dive and total time at sea on or near the bottom than adults. Immature sea lions also spent a higher percentage of time at sea diving. 5. Juveniles may have to work harder because they are weaned before reaching full diving capability. For benthic foragers, reduced diving ability limits available foraging habitat. Furthermore, as juveniles appear to operate close to their physiological maximum, they would have a difficult time increasing foraging effort in response to reductions in prey. Although benthic prey are less influenced by seasonal fluctuations and oceanographic perturbations than epipelagic prey, demersal fishery trawls may impact juvenile survival by disrupting habitat and removing larger size classes of prey. These issues may be an important factor as to why the Australian sea lion population is currently at risk.     

Lung size and thoracic morphology in shallow‐ and deep‐diving cetaceans

Shallow‐diving, coastal bottlenose dolphins (Tursiops truncatus) and deep‐diving, pelagic pygmy and dwarf sperm whales (Kogia breviceps and K. sima) will experience vastly different ambient pressures at depth, which will influence the volume of air within their lungs and potentially the degree of thoracic collapse they experience. This study tested the hypotheses that lung size will be reduced and/or thoracic mobility will be enhanced in deeper divers. Lung mass (T. truncatus, n = 106; kogiids, n = 18) and lung volume (T. truncatus, n = 5; kogiids, n = 4), relative to total body mass, were compared. One T. truncatus and one K. sima were cross‐sectioned to calculate lung, thoracic vasculature, and other organ volumes. Excised thoraxes (T. truncatus, n = 3; kogiids, n = 4) were mechanically manipulated to compare changes in thoracic cavity shape and volume. Kogiid lungs were half the mass and one‐fifth the volume of those of similarly sized T. truncatus. The lungs occupied only 15% of the total thoracic cavity volume in K. sima and 37% in T. truncatus. The kogiid and dolphin thoraxes underwent similar changes in shape and volume, although the width of the thoracic inlet was relatively constrained in kogiids. A broader phylogenetic comparison demonstrated that the ratio of lung mass to total body mass in kogiids, physeterids, and ziphiids was similar to that of terrestrial mammals, while delphinids and phocoenids possessed relatively large lungs. Thus, small lung size in deep‐diving odontocetes may be a plesiomorphic character. The relatively large lung size of delphinids and phocoenids appears to be a derived condition that may permit the lung to function as a site of respiratory gas exchange throughout a dive in these rapid breathing, short‐duration, shallow divers. J. Morphol., 2010. © 2010 Wiley‐Liss, Inc.     

Resting metabolic rate and lung function in fasted and fed rough-toothed dolphins,Steno bredanensis

We measured resting metabolic rate (RMR), tidal volume (V_T), breathing frequency (f_R), respiratory flow, and end-expired gases in rough-toothed dolphins (Steno bredanensis) housed in managed care after an overnight fast and 1–2 hr following a meal. The measured average (± standard deviation) V_T (4.0 ± 1.3 L) and f_R (1.9 ± 1.0 breaths/min) were higher and lower, respectively, as compared with estimated values from both terrestrial and aquatic mammals, and the average V_T was 43% of the estimated total lung capacity. The end-expired gas levels suggested that this species keep alveolar O₂ (10.6% or 80 mmHg) and CO₂ (7.6% or 57 mmHg), and likely arterial gas tensions, low and high, respectively, to maximize efficiency of gas exchange. We show that following an overnight fast, the RMR (566 ± 158 ml O₂/min) was 1.8 times the estimated value predicted by Kleiber for terrestrial mammals of the same size. We also show that between 1 and 2 hr after ingestion of a meal, the metabolic rate increases an average of 29% (709 ± 126 ml O₂/min). Both body mass (M_b) and f_R significantly altered the measured RMR and we propose that both these variables should be measured when estimating energy use in cetaceans.     

Microvascular characteristics of the acoustic fats: Novel data suggesting taxonomic differences between deep and shallow‐diving odontocetes

Odontocetes have specialized mandibular fats, the extramandibular (EMFB) and intramandibular fat bodies (IMFB), which function as acoustic organs, receiving and channeling sound to the ear during hearing and echolocation. Recent strandings of beaked whales suggest that these fat bodies are susceptible to nitrogen (N₂) gas embolism and empirical evidence has shown that the N₂ solubility of these fat bodies is higher than that of blubber. Since N₂ gas will diffuse from blood into tissue at any blood/tissue interface and potentially form gas bubbles upon decompression, it is imperative to understand the extent of microvascularity in these specialized acoustic fats so that risk of embolism formation when diving can be estimated. Microvascular density was determined in the EMFB, IMFB, and blubber from 11 species representing three odontocete families. In all cases, the acoustic tissues had less (typically 1/3 to 1/2) microvasculature than did blubber, suggesting that capillary density in the acoustic tissues may be more constrained than in the blubber. However, even within these constraints there were clear phylogenetic differences. Ziphiid (Mesoplodon and Ziphius, 0.9 ± 0.4% and 0.7 ± 0.3% for EMFB and IMFB, respectively) and Kogiid families (1.2 ± 0.2% and 1.0 ± 0.01% for EMFB and IMFB, respectively) had significantly lower mean microvascular densities in the acoustic fats compared to the Delphinid species (Tursiops, Grampus, Stenella, and Globicephala, 1.3 ± 0.3% and 1.3 ± 0.3% for EMFB and IMFB, respectively). Overall, deep‐diving beaked whales had less microvascularity in both mandibular fats and blubber compared to the shallow‐diving Delphinids, which might suggest that there are differences in the N₂ dynamics associated with diving regime, phylogeny, and tissue type. These novel data should be incorporated into diving physiology models to further understand potential functional disruption of the acoustic tissues due to changes in normal diving behavior.     

Running, swimming and diving modifies neuroprotecting globins in the mammalian brain

The vulnerability of the human brain to injury following just a few minutes of oxygen deprivation with submergence contrasts markedly with diving mammals, such as Weddell seals (Leptonychotes weddellii), which can remain underwater for more than 90 min while exhibiting no neurological or behavioural impairment. This response occurs despite exposure to blood oxygen levels concomitant with human unconsciousness. To determine whether such aquatic lifestyles result in unique adaptations for avoiding ischaemic-hypoxic neural damage, we measured the presence of circulating (haemoglobin) and resident (neuroglobin and cytoglobin) oxygen-carrying globins in the cerebral cortex of 16 mammalian species considered terrestrial, swimming or diving specialists. Here we report a striking difference in globin levels depending on activity lifestyle. A nearly 9.5-fold range in haemoglobin concentration (0.17-1.62 g Hb 100 g brain wet wt(-1)) occurred between terrestrial and deep-diving mammals; a threefold range in resident globins was evident between terrestrial and swimming specialists. Together, these two globin groups provide complementary mechanisms for facilitating oxygen transfer into neural tissues and the potential for protection against reactive oxygen and nitrogen groups. This enables marine mammals to maintain sensory and locomotor neural functions during prolonged submergence, and suggests new avenues for averting oxygen-mediated neural injury in the mammalian brain.     

Assessment of scale-dependent foraging behaviour in southern elephant seals incorporating the vertical dimension: a development of the First Passage Time method

1. Identifying the spatial scales at which top marine predators forage is important for understanding oceanic ecosystems. Several methods quantify how individuals concentrate their search effort along a given path. Among these, First-Passage Time (FPT) analysis is particularly useful to identify transitions in movement patterns (e.g. between searching and feeding). This method has mainly been applied to terrestrial animals or flying seabirds that have little or no vertical component to their foraging, so we examined the differences between classic FPT and a modification of this approach using the time spent at the bottom of a dive for characterizing the foraging activity of a diving predator: the southern elephant seal. 2. Satellite relayed data loggers were deployed on 20 individuals during three successive summers at the Kerguelen Islands, providing a total of 72 978 dives from eight juvenile males and nine adult females. 3. Spatial scales identified using the time spent at the bottom of a dive ( = 68.2 +/- 42.1 km) were smaller than those obtained by the classic FPT analysis ( = 104.7 +/- 67.3 km). Moreover, foraging areas identified using the new approach clearly overlapped areas where individuals increased their body condition, indicating that it accurately reflected the foraging activity of the seals. 4. These results suggest that incorporating the vertical dimension into FPT provides a different result to the surface path alone. Close to the Antarctic continent, within the pack-ice, sinuosity of the path could be explained by a high sea-ice concentration (restricting elephant seal movements), and was not necessarily related to foraging activity. 5. Our approach distinguished between actual foraging activity and changes in behaviour induced by the physical environment like sea ice, and could be applied to other diving predators. Inclusion of diving parameters appears to be essential to identify the spatial scale of foraging areas of diving animals.     

正常分钟通气量机械通气不同潮气量和频率影响活体山羊颈动脉血氧动态变化的初步实验研究*

目的: 在初步验证超快反应聚合物基质光纤氧传感器及其测定系统记录颈动脉氧分压（PaO₂）连续动态变化使用基础上,为了分析探讨肺通气对PaO₂连续动态变化的影响,我们设计本活体整体动物实验观察研究。方法: 选择杂种山羊4只,全身麻醉气管插管空气机械通气下,切皮直接暴露把后接测定系统的氧传感器直接插入左侧颈动脉连续记录PaO₂动态变化。正常分钟通气量机械通气分别通过三种潮气量实施：正常潮气量（潮气量VT=15 ml/kg、呼吸频率Rf=20 bpm）、减半潮气量（VT减半、Rf加倍）和加倍潮气量（VT加倍、Rf减半）。三种潮气量通气时间分别稳定10~15 min,选取后180 s分析计算PaO₂平均值、呼吸间PaO₂变化的升降幅度和肺-颈动脉延迟时间。以ANOVA及两两比较统计学差异分析不同潮气量的影响。结果: 活体山羊正常通气量机械通气实验时心率和血压均稳定;肺-颈动脉延迟时间为1.4~1.8 s（约为此时的3次心跳）。机械通气正常潮气量下PaO₂平均值在（102.94±2.40,99.38~106.16）mmHg,升降幅度是（21.43±1.65,19.21~23.59）mmHg,占平均值的（20.80±1.34,18.65~22.22）%;减半潮气量下,PaO₂平均值维持在（101.01±4.25,94.09~105.66）mmHg,虽略降但不显著（与正常机械通气比较P>0.05）,但PaO₂升降变化幅度却显著降低为（18.14±1.43,16.46~20.05） mmHg,占平均值的（17.95±1.07,16.16~18.98）%（与正常机械通气比较P<0.01）;加倍潮气量机械通气下,虽仅略升的PaO₂平均值维持在（106.42±4.74,101.19~114.08）mmHg（与正常机械通气比较P>0.05,与减半潮气量机械通气比较P<0.05）,但PaO₂升降幅度却显著增大为（26.58±1.88,23.46~28.46）mmHg,占平均值的24.99%±1.58%（与正常机械通气和减半潮气量比较P均<0.01）。结论: 正常肺通气的吸气和呼气是颈动脉PaO₂上升和下降的始动因素。正常通气量机械通气下减半潮气量和倍增潮气量显著改变PaO₂升降幅度,但PaO₂平均值仅小幅改变,而肺-颈动脉延迟时间相近。     

Seasonal variation in blood and muscle oxygen stores attributed to diving behavior, environmental temperature and pregnancy in a marine predator, the California sea lion

Survival depends on an animal's ability to find and acquire prey. In diving vertebrates, this ability is directly related to their physiological capability (e.g. oxygen stores). We studied the seasonal variation in oxygen stores, body temperature and body condition in California sea lions (Zalophus californianus) (CSL) as a function of seasonal variation in temperature, primary productivity, diving behavior and reproductive stage. During summer, blood oxygen stores were significantly greater and muscle oxygen stores were significantly lower than in winter. Total oxygen stores, body condition and body temperature did not change between seasons but variations in body temperature were greater during summer. Changes in oxygen stores are partly attributed to diving behavior, temperature and pregnancy that could increase oxygen consumption. Blood and muscle oxygen stores appear to be influenced by reproductive state. Blood oxygen stores are more likely influenced by diving behavior and temperature than muscle oxygen stores.     

Olfaction at depth: Cribriform plate size declines with dive depth and duration in aquatic arctoid carnivorans

It is widely accepted that obligate aquatic mammals, specifically toothed whales, rely relatively little on olfaction. There is less agreement about the importance of smell among aquatic mammals with residual ties to land, such as pinnipeds and sea otters. Field observations of marine carnivorans stress their keen use of smell while on land or pack ice. Yet, one dimension of olfactory ecology is often overlooked: while underwater, aquatic carnivorans forage “noseblind,” diving with nares closed, removed from airborne chemical cues. For this reason, we predicted marine carnivorans would have reduced olfactory anatomy relative to closely related terrestrial carnivorans. Moreover, because species that dive deeper and longer forage farther removed from surface scent cues, we predicted further reductions in their olfactory anatomy. To test these hypotheses, we looked to the cribriform plate (CP), a perforated bone in the posterior nasal chamber of mammals that serves as the only passageway for olfactory nerves crossing from the periphery to the olfactory bulb and thus covaries in size with relative olfactory innervation. Using CT scans and digital quantification, we compared CP morphology across Arctoidea, a clade at the interface of terrestrial and aquatic ecologies. We found that aquatic carnivoran species from two lineages that independently reinvaded marine environments (Pinnipedia and Mustelidae), have significantly reduced relative CP than terrestrial species. Furthermore, within these aquatic lineages, diving depth and duration were strongly correlated with CP loss, and the most extreme divers, elephant seals, displayed the greatest reductions. These observations suggest that CP reduction in carnivorans is an adaptive response to shifting selection pressures during secondary invasion of marine environments, particularly to foraging at great depths. Because the CP is fairly well preserved in the fossil record, using methods presented here to quantify CP morphology in extinct species could further clarify evolutionary patterns of olfactory loss across aquatic mammal lineages that have independently committed to life in water.     

超快速反应聚合物光纤氧测定装置及其用于活体动物机械通气下动脉血氧分压连续动态变化的初步实验报告*

目的: 我们在中国尝试使用超快反应聚合物光纤氧感受器置入整体活体动物动脉血管,再通过光电转换测定系统以记录活体动物颈动脉PO₂（PaO₂）连续动态的快速变化,为完善整体整合生理学理论体系中循环参与呼吸调控和呼吸循环代谢一体化调控提供实验依据。方法: ①超快反应氧感受器制作、性能及其测定系统标定：在实验室加热总长2 m光纤的远端5 mm部分,拉动直到它成锥形尖端,清洁并干燥后,将1 mm锥形光纤尖端浸涂到发光体掺杂聚合物溶液中,在溶剂快速蒸发同时将其缓慢抽出来形成氧气感测尖端,室温干燥24 h。对完成制作的感受器进行性能标定,并于第37日重复标定。②动物实验：在潍坊医学院实验室对山羊全麻气管插管氧气机械通气下,切皮暴露双颈动脉和左侧股动脉,分别把超快反应氧传感器直接插入动脉中,通过光导纤维、激发与检测Y型光纤耦合器经光电转换连接到个人电脑,实现机械通气下活体山羊颈动脉PaO₂的连续动态反应,主要分析PaO₂的呼吸间波浪式交替升降和肺-颈动脉时间延迟。结果: 该置入式超快反应氧传感器在液相的响应时间为100 ms。活体山羊实验40%~60%氧气机械通气心率和血压稳定,左和右颈动脉PaO₂随着呼吸机的吸气和呼气呈现波浪式上升和下降的呼吸交替现象,幅度高达15 mmHg;左侧股动脉位置记录的信息噪音显著干扰PaO₂变化。肺-颈动脉时间延迟是在吸气和呼气开始后1.5~1.7 s左侧和右侧颈动脉PaO₂都开始上升和下降;即肺通气开始后3次心跳,左心室可把肺毛细血管后动脉化的肺静脉血液送到外周化学感受器位置中断吸气切换为呼气和中断呼气切换为吸气,如此实现吸呼周而复始。结论: 活体动物置入动脉的超快反应氧传感器及其测定系统可测定PaO₂生理性波浪式变化,能为整体整合生理学医学新理论体系中解释吸气和呼气相互切换的机制提供实验依据。     

Mitochondria, reactive oxygen species and longevity: some lessons from the Barja group

To demonstrate that an uncoupling of respiration and phosphorylation, measured in vitro, reflects an in vivo situation, we badly need in vivo measurements of some uncoupling-linked parameters. The importance of this assertion is illustrated by studies of Barja and co-workers. A lower rate of H(2)O(2) production by mitochondria isolated from long-lived birds compared with short-lived mammals of the same body weight (see publications by Barja's and Sohal's groups) could be explained by (i) an in vivo difference or (ii) an in vitro artefact. In both cases, the reason for lower H(2)O(2) production may well be the same, i.e. a mild uncoupling of respiration in avian mitochondria showing lowered respiratory control. Again, this should be due to an in vivo operation of some bird-specific natural uncouplers (the first case) or stronger in vitro damage to the avian mitochondria during their isolation and incubation (the second). The latter possibility seemed more probable when Barja and co-workers revealed that the level of antioxidants in birds is lower than in mammals. However, further studies by the same group showed that the degree of unsaturation of fatty acids in birds is lower than in mammals, indicating a greater resistance of avian mitochondria to oxidative damage in vitro. Indeed, it was found that lipid peroxidation in isolated avian mitochondria occurs at a much lower rate than in mammals. More importantly, the in vivo level of peroxidation of lipids and proteins appears to be lower in birds than in mammals. Thus, it seems probable that longer lifespan of birds really does correlate with a slower rate of production of H2O2 by mitochondria in vivo.     

Fluid balance versus blood flow autoregulation in the elevated human limb: the role of venous collapse

This study evaluated the postural vascular adjustment in the human forearm which may be responsible for the recent observation that transcapillary fluid balance is maintained above the level of the heart while blood flow decreases in a linear fashion. In this study further evidence was provided that a posturally graded profile of collapsed veins holds for both an overall increase of resistance with height and compensation for hydrostatic effects on capillary pressure. This was achieved by manipulating peripheral venous profile/volume: a proximal outlet resistance (upper arm cuff) was used for re-opening of collapsed distal veins. In test (a), 12 healthy subjects underwent recordings of fluid reabsorption rate and blood flow in a 20-cm segment of their forearm horizontally placed at 36 cm above heart level (third intercostal space). Applying upper arm cuff pressures randomly between 0 and 25 mmHg (0–3.33 kPa) for 15 min led to maxima of blood flow and reabsorption rates at inflations of 5 or 10 mmHg (0.67 or 1.33 kPa). This was attributed to minima in postcapillary resistance facilitating flow and reducing capillary pressure. In test (b) the flow-maximizing outlet resistance found was studied for its effect in different forearm positions (–18, 0, 18, 36, 54 cm relative to heart level). Blood flow then showed a shift of its maximum from heart level to 36 cm above heart level, while the reabsorption rate increased above 18-cm height - in contrast to previous findings with a free circulation. It was therefore concluded that the venous profile in the forearm adjusts postcapillary resistance in such a way that local dehydration is confined at the cost of blood supply. Thicker and less collapsable veins may ensure better flow autoregulation during impaired fluid balance — as seen in the legs.     

Sexual dimorphism and sexual conflict in the diving beetle Agabus uliginosus (L.) (Coleoptera: Dytiscidae)

Sexual conflict can drive intersexual arms races, with female resistance and male persistence traits coevolving antagonistically. Such arms races are well documented in some diving beetles, although the extent of sexual conflict in this family remains unclear. The European dytiscid Agabus uliginosus has a strikingly dimorphic female; individuals from most regions are smooth and male‐like, whereas those from some populations have a strongly roughened dorsum, a trait that has attracted the name dispar. We demonstrate that rough and smooth females differ consistently in the development of dorsal surface microreticulation, and that these females are associated with males that differ in the development of their persistence traits. These findings extend the occurrence of pre‐insemination sexual conflict and associated intrasexual dimorphism in Dytiscidae, and suggest that such mating systems are relatively widespread in these beetles.     

Analysis of metabolic alterations in Arabidopsis following changes in the carbon dioxide and oxygen partial pressures

As sessile organisms, plants are subject to a multitude of environmental variations including several which directly affect their interaction with the atmosphere. Given the indiscriminant nature of Rub...     

Long-term continuous monitoring of dissolved oxygen in cell culture medium for perfused bioreactors using optical oxygen sensors

For long-term growth of mammalian cells in perfused bioreactors, it is essential to monitor the concentration of dissolved oxygen (DO) present in the culture medium to ascertain the health of the cells. An optical oxygen sensor based on dynamic fluorescent quenching was developed for long-term continuous measurement of DO for NASA-designed rotating perfused bioreactors. Tris(4,7-diphenyl-1,10-phenanthroline) ruthenium(II) chloride is employed as the fluorescent dye indicator. A pulsed, blue LED was chosen as the excitation light source. The sensor can be sterilized using an autoclave. The sensors were tested in a perfused rotating bioreactor supporting a BHK-21 (baby hamster kidney) cell culture over one 28-day, one 43-day, and one 180-day cell runs. The sensors were initially calibrated in sterile phosphate-buffered saline (PBS) against a blood-gas analyzer (BGA), and then used continuously during the entire cell culture without recalibration. In the 180-day cell run, two oxygen sensors were employed; one interfaced at the outlet of the bioreactor and the other at the inlet of the bioreactor. The DO concentrations determined by both sensors were compared with those sampled and measured regularly with the BGA reference. The sensor outputs were found to correlate well with the BGA data throughout the experiment using a single calibration, where the DO of the culture medium varied between 25 and 60 mm Hg at the bioreactor outlet and 80-116 mm Hg at the bioreactor inlet. During all 180 days of culture, the precision and the bias were +/-5.1 mm Hg and -3.8 mm Hg at the bioreactor outlet, and +/- 19 mm Hg and -18 mm Hg at inlet. The sensor dynamic range is between 0 and 200 mm Hg and the response time is less than 1 minute. The resolution of the sensor is 0.1 mm Hg at 50 mm Hg, and 0.25 mm Hg at 130 mm Hg.     

长期太极拳运动对中老年人膝关节皮肤微血管反应性、经皮氧分压的影响*

目的: 探讨长期太极拳运动对中老年人膝关节皮肤微血管反应性、经皮氧分压的影响。方法: 以湖北省恩施州土家族苗族自治州太极拳爱好者协会26名系统练习(每周至少练习三次,每次不少于90 min)太极拳超过2年的成员为运动组(54.6± 4.0)岁,26名同年龄段健康的普通人为对照组(53.2±5.1)岁,两组受试者男女比例均为1∶1。使用第六代(最新一代)激光多普勒血流检测仪(PF6010)对研究对象膝关节表面中心的皮肤进行检测,测试指标包括血细胞平均运动速度(AVBC)、运动血细胞浓度(CMBC)、微血管血流灌注量(MBP)、经皮氧分压(TcpO2)。其中AVBC、CMBC、MBP先进行5 min的基础值测试(基础值),然后将测试探头加热到44℃并持续10 min(加热后值),TcpO2测试值为探头直接加热到44℃值。结果: 与对照组相比,运动组的MBP基础值有所降低,但无统计学意义(P＞0.05);MBP的加热后值与增加率显著升高(P＜0.05),CMBC的增加率显著降低(P＜0.05),AVBC的增加率显著升高(P＜0.05),TcpO2有所升高,但无统计学意义(P＞0.05)。结论: 长期系统的太极拳运动可提高中老年人膝关节皮肤微血管的反应性和经皮氧分压。     

脓毒症患者PtcO2PtcCO2的监测意义及对预后的评估作用研究

目的:探讨脓毒症患者无创经皮组织氧分压(tcpO_2)和二氧化碳分压(tcpCO_2)的监测意义及用于患者预后评估的价值。方法:选择2016年1月至2018年12月我院接诊的80例脓毒症患者进行研究,根据监测方式的不同分为观察组(n=50)和对照组(n=30)。对照组患者采用常规监测动脉血气,观察组患者采用经皮氧分压/二氧化碳分压连续监测,并根据相关数据指导液体复苏,提高氧输送,并追踪患者预后。分析和比较两组的tcpO_2、tcpCO_2、氧偏移度及急性生理与慢性健康评分Ⅱ(APACHEⅡ)在脓毒症的变化及诊断价值。结果:观察组患者tcpO_2、tcpCO_2、氧偏移度及APACHEⅡ均明显高于对照组(P0.05);两组死亡组患者tcpO_2、氧偏移度及APACHEⅡ均显著高于存活组、而tcpCO_2低于存活组(P0.05);logistic回归分析显示tcpO_2、tcpCO_2均与氧偏移度及APACHEⅡ呈显著正相关(P0.05);tcpO_2诊断脓毒症的AUC为0.806,95%CI为0.710～0.902;tcpCO_2诊断脓毒症的AUC为0.723,95%CI为0.608～0.839;氧偏移度诊断脓毒症的AUC为0.970,95%CI为0.938～1.000;APACHEⅡ诊断脓毒症的AUC为0.932,95%CI为0.879～0.985;联合检测诊断脓毒症的AUC为0.997,95%CI为0.989～1.000,联合检测的特异度、准确度分别为93.74%、95.68%,显著高于各指标单独检测(P0.05)。结论:经皮氧/二氧化碳分压监测装置早期监测有助于早期评估脓毒症的严重程度与预后。