109 research outputs found
Blood Pressure in Patients with Intermittent Claudication Increases Continuously During Walking
ObjectivesThe purpose of this study was to compare the circulatory responses to walking in patients with peripheral atherosclerotic disease (PAD) and healthy controls.MethodsThe participants were eleven patients with diagnosed PAD, and a control group of six healthy age-matched adults. Blood pressure, heart rate (HR), and acral skin perfusion were recorded continuously before, during and after a walking exercise on a treadmill.ResultsThe patients walked to maximum claudication distance (MCD) on a treadmill, median walking distance 103 (34â223) metres [median (range)], at 3.3 (1.0â4.5) km/h. There was a steep increase in HR and mean arterial pressure (MAP) while the patients were walking. At claudication the median rise in MAP was 46.6 (10.3â61.3) mmHg, systolic blood pressure (SP) increased by 84.9 (31.4â124.9) mmHg, and diastolic blood pressure (DP) by 21.7 (â2.1â31.7) mmHg. HR increased by 34.9 (12.9â48.1) beats/min. The control group walked for 5 minutes at 3.2 (3.0â3.3) km/h. In the control group the blood pressure initially increased moderately but stabilised thereafter. Median rise in MAP during walking was 8.5 (5.6â14.6) mmHg, SP increased by 30.9 (6.6â41.5) mmHg, and DP was reduced by â1.4 (â5.4â1.5) mmHg. HR increased by 27.1 (18.8â34.9) beats/min. We found no significant differences in acral skin perfusion during walking exercise between the patients and control group.ConclusionsIn patients with PAD, blood pressure increased continuously and significantly when walking to MCD (dynamic exercise). The level of increase in blood pressure was similar to that caused in response to isometric exercise
Intermittent mild negative pressure applied to the lower limb in patients with spinal cord injury and chronic lower limb ulcers: a crossover pilot study
Study design
Randomized, assessor-blinded crossover pilot study.
Objectives
To explore the use of an intermittent negative pressure (INP) device for home use in addition to standard wound care (SWC) for patients with spinal cord injury (SCI) and chronic leg and foot ulcers before conducting a superiority trial.
Setting
Patient homes and outpatient clinic.
Methods
A 16-week crossover trial on 9 SCI patients (median age: 57 years, interquartile range [IQR] 52â66), with leg ulcers for 52 of weeks (IQR: 12â82) duration. At baseline, patients were allocated to treatment with INPâ+âSWC or SWC alone. After 8 weeks, the ulcers were evaluated. To assess protocol adherence, the patients were then crossed over to the other group and were evaluated again after another 8 weeks. Lower limb INP treatment consisted of an airtight pressure chamber connected to an INP generator (alternating 10âs â40mmHg/7âs atmospheric pressure) used 2âh/day at home. Ulcer healing was assessed using a photographic wound assessment tool (PWAT) and by measuring changes in wound surface area (WSA).
Results
Seven of nine recruited patients adhered to a median of 90% (IQR: 80â96) of the prescribed 8-week INP-protocol, and completed the study without side effects. PWAT improvement was observed in 4/4 patients for INPâ+âSWC vs. 2/5 patients for SWC alone (Pâ=â0.13). WSA improved in 3/4 patients allocated to INPâ+âSWC vs. 3/5 patients in SWC alone (Pâ=â0.72).
Conclusions
INP can be used as a home-based treatment for patients with SCI, and its efficacy should be tested in an adequately sized, preferably multicenter randomized trial.mÄsjekke
Factors mediating the pressor response to isometric muscle contraction: An experimental study in healthy volunteers during lower body negative pressure.
Whilst both cardiac output (CO) and total peripheral resistance (TPR) determine mean arterial blood pressure (MAP), their relative importance in the pressor response to isometric exercise remains unclear. This study aimed to elucidate the relative importance of these two different factors by examining pressor responses during cardiopulmonary unloading leading to step-wise reductions in CO. Hemodynamics were investigated in 11 healthy individuals before, during and after two-minute isometric exercise during lower body negative pressure (LBNP; -20mmHg and -40mmHg). The blood pressure response to isometric exercise was similar during normal and reduced preload, despite a step-wise reduction in CO during LBNP (-20mmHg and -40mmHg). During -20mmHg LBNP, the decreased stroke volume, and consequently CO, was counteracted by an increased TPR, while heart rate (HR) was unaffected. HR was increased during -40 mmHg LBNP, although insufficient to maintain CO; the drop in CO was perfectly compensated by an increased TPR to maintain MAP. Likewise, transient application of LBNP (-20mmHg and -40mmHg) resulted in a short transient drop in MAP, caused by a decrease in CO, which was compensated by an increase in TPR. This study suggests that, in case of reductions of CO, changes in TPR are primarily responsible for maintaining the pressor response during isometric exercise. This highlights the relative importance of TPR compared to CO in mediating the pressor response during isometric exercise
Nitrate stable isotopes and major ions in snow and ice samples from four Svalbard sites
Increasing reactive nitrogen (N-r) deposition in the Arctic may adversely impact N-limited ecosystems. To investigate atmospheric transport of N-r to Svalbard, Norwegian Arctic, snow and firn samples were collected from glaciers and analysed to define spatial and temporal variations (1 10 years) in major ion concentrations and the stable isotope composition (delta N-15 and delta O-18) of nitrate (NO3-) across the archipelago. The delta N-15(NO3-) and delta O-18(NO3-) averaged -4 parts per thousand and 67 parts per thousand in seasonal snow (2010-11) and -9 parts per thousand and 74 parts per thousand in firn accumulated over the decade 2001-2011. East-west zonal gradients were observed across the archipelago for some major ions (non-sea salt sulphate and magnesium) and also for delta N-15(NO3-) and delta O-18(NO3-) in snow, which suggests a different origin for air masses arriving in different sectors of Svalbard. We propose that snowfall associated with long-distance air mass transport over the Arctic Ocean inherits relatively low delta N-15(NO3-) due to in-transport N isotope fractionation. In contrast, faster air mass transport from the north-west Atlantic or northern Europe results in snowfall with higher delta N-15(NO3-) because in-transport fractionation of N is then time-limited
Air temperature variations and gradients along the coast and fjords of western Spitsbergen
Daily temperature measurements from six meteorological stations along the coast and fjords of western Spitsbergen have been digitized and quality controlled in a Norwegian, Russian and Polish collaboration. Complete daily data series have been reconstructed back to 1948 for all of the stations. One of the stationâs monthly temperature series has previously been extended back to 1898 and is included in this study. The long-term series show large temperature variability on western Spitsbergen with colder periods in the 1910s and 1960s and warmer periods in the 1930s, 1950s and in the 21st century. The most recent years are the warmest ones in the instrumental records. There is a
positive and statistically significant trend in the annual times series for all of the stations; however, the strongest warming is seen in winter and spring. For the period 1979-2015, the linear trends range from 1.0 to 1.38°C/decade for the annual series and from 2.0 to 2.38°C/decade in winter. Threshold statistics demonstrate a decrease in the number of cold days per year and an increase in the number of warm days. A decreasing inter-annual variability is observed. In winter, spring and autumn, the stations in the northernmost areas of west Spitsbergen and in the innermost parts of Isfjorden are the coldest ones. In summer, however, the southernmost station is the coldest one
Light in the Polar Night
How much light isa vailable for biological processes during Polar Night? This question appears simple enough. But the reality is that conventional light sen- sors for measuring visible light (~350 to ~700 nm) have not been sensitive enough to answer it. Beyond this technical challenge, âlightâ is a general term that must be qualified in terms of âlight climateâ before it has meaning for biological systems. In this chapter, we provide an answer to the question posed above and explore aspects of light climate during Polar Night with relevance to biology, specifically, how Polar Night is defined by solar elevation, atmospheric light in Polar Night and its propaga- tion underwater, bioluminescence in Polar Night and the concept of Polar Night as a deep-sea analogue, light pollution, and future perspectives. This chapter focuses on the quantity and quality of light present during Polar Night, while subsequent chapters in this volume focus on specific biological effects of this light for algae (Chap. âMarine Micro- and Macroalgae in the Polar Nightâ), zooplankton (Chaps.âZooplankton in the Polar Nightâ and âBiological Clocks and Rhythms in Polar Organismsâ), and fish (Chap. âFish Ecology in the Polar Nightâ)
The effects of shoulder load and pinch force on electromyographic activity and blood flow in the forearm during a pinch task
The object of the current study was to determine whether static contraction of proximal musculature has an effect on the blood flow more distally in the upper extremity. Static contractions of muscles in the neck shoulder region at three levels (relaxed, shoulders elevated and shoulders elevated loaded with 4.95 kg each) were combined with intermittent pinch forces at 0, 10 and 25% of the maximum voluntary contraction (MVC). Blood flow to the forearm was measured with Doppler ultrasound. Myoelectric activity of the forearm and neck-shoulder muscles was recorded to check for the workload levels. Across all levels of shoulder load, blood flow increased significantly with increasing pinch force (21% at 10% MVC and by 44% at 25% MVC). Blood flow was significantly affected by shoulder load, with the lowest blood flow at the highest shoulder load. Interactions of pinch force and shoulder load were not significant. The myoelectric activity of forearm muscles increased with increasing pinch force. The activation of the trapezius muscle decreased with increasing pinch force and increased with increasing shoulder load. The precise mechanisms accounting for the influence of shoulder load remains unclear. The results of this study indicate that shoulder load might influence blood flow to the forearm
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