Dive response of children in relation to cold-water near-drowning

1987 ◽  
Vol 63 (2) ◽  
pp. 665-668 ◽  
Author(s):  
C. A. Ramey ◽  
D. N. Ramey ◽  
J. S. Hayward
Keyword(s):  
Water Temperature ◽  
Significant Contribution ◽  
Cold Water ◽  
Breath Hold ◽  
Age Dependency ◽  
Near Drowning ◽  
Experimental Findings ◽  
Dive Response ◽  
Breath Hold Duration

The strength of the dive response, as judged by the combination of breath-hold duration (BHD) and bradycardia, was compared in 87 children (4–13 yr old) and 68 adults (20–68 yr old) during simulated dives in 29 degrees C water. Mean BHD in children (16.1 s) was only 37.4% (P less than 0.001) of adult BHD (43.0 s). Within children, BHD was significantly (P less than 0.001) dependent on age (A in yr) according to the regression BHD = -1.46 + 2.27A. No age dependency of BHD occurred in adults. Due to the low BHD of children, only 14/87 (16.1%) were able to breath hold for the 25 s necessary to develop full diving bradycardia. For these 14 children, their bradycardia (36.1% reduction) was insignificantly different (P greater than 0.50) from that of adults (36.4%). These experimental findings demonstrate that the dive response of children is extremely weak, due mainly to their very low BHD. Since lower water temperature would probably accentuate the shortness of BHD (according to previous findings for adults), it is concluded that the dive response is unlikely to make a significant contribution to the prolonged resuscitatibility of children who are victims of cold-water near-drowning.

Temperature effect on the human dive response in relation to cold water near-drowning

1984 ◽  
Vol 56 (1) ◽  
pp. 202-206 ◽  
Author(s):  
J. S. Hayward ◽  
C. Hay ◽  
B. R. Matthews ◽  
C. H. Overweel ◽  
D. D. Radford
Keyword(s):  
Heart Rate ◽  
Water Temperature ◽  
Cold Water ◽  
Breath Holding ◽  
Breath Hold ◽  
Cold Stimulation ◽  
Near Drowning ◽  
Voluntary Hyperventilation ◽  
Dive Response ◽  
Breath Hold Duration

To facilitate analysis of mechanisms involved in cold water near-drowning, maximum breath-hold duration (BHD) and diving bradycardia were measured in 160 humans who were submerged in water temperatures from 0 to 35 degrees C at 5 degrees C intervals. For sudden submersion BHD was dependent on water temperature (Tw) according to the equation BHD = 15.01 + 0.92Tw. In cold water (0–15 degrees C), BHD was greatly reduced, being 25–50% of the presubmersion duration. BHD after brief habituation to water temperature and mild, voluntary hyperventilation was more than double that of sudden submersion and was also dependent on water temperature according to the equation BHD = 38.90 + 1.70Tw. Minimum heart rate during both types of submersions (diving bradycardia) was independent of water temperature. The results are pertinent to accidental submersion in cold water and show that decreased breath-holding capacity caused by peripheral cold stimulation reduces the effectiveness of the dive response and facilitates drowning. These findings do not support the postulate that the dive response has an important role in the enhanced resuscitatibility associated with cold water near-drowning, thereby shifting emphasis to hypothermia as the mechanism for this phenomenon.

Skin Cooling on Breath-Hold Duration and Predicted Emergency Air Supply Duration During Immersion

2020 ◽  
Vol 91 (7) ◽  
pp. 578-585
Author(s):  
Victory C. Madu ◽  
Heather Carnahan ◽  
Robert Brown ◽  
Kerri-Ann Ennis ◽  
Kaitlyn S. Tymko ◽  
...  
Keyword(s):  
Minute Ventilation ◽  
Hold Time ◽  
Whole Body ◽  
Breath Hold ◽  
Endurance Time ◽  
Skin Exposure ◽  
Breathing Apparatus ◽  
Air Supply ◽  
Skin Cooling ◽  
Breath Hold Duration

PURPOSE: This study was intended to determine the effect of skin cooling on breath-hold duration and predicted emergency air supply duration during immersion.METHODS: While wearing a helicopter transport suit with a dive mask, 12 subjects (29 ± 10 yr, 78 ± 14 kg, 177 ± 7 cm, 2 women) were studied in 8 and 20°C water. Subjects performed a maximum breath-hold, then breathed for 90 s (through a mouthpiece connected to room air) in five skin-exposure conditions. The first trial was out of water for Control (suit zipped, hood on, mask off). Four submersion conditions included exposure of the: Partial Face (hood and mask on); Face (hood on, mask off); Head (hood and mask off); and Whole Body (suit unzipped, hood and mask off).RESULTS: Decreasing temperature and increasing skin exposure reduced breath-hold time (to as low as 10 ± 4 s), generally increased minute ventilation (up to 40 ± 15 L · min−1), and decreased predicted endurance time (PET) of a 55-L helicopter underwater emergency breathing apparatus. In 8°C water, PET decreased from 2 min 39 s (Partial Face) to 1 min 11 s (Whole Body).CONCLUSION: The most significant factor increasing breath-hold and predicted survival time was zipping up the suit. Face masks and suit hoods increased thermal comfort. Therefore, wearing the suits zipped with hoods on and, if possible, donning the dive mask prior to crashing, may increase survivability. The results have important applications for the education and preparation of helicopter occupants. Thermal protective suits and dive masks should be provided.Madu VC, Carnahan H, Brown R, Ennis K-A, Tymko KS, Hurrie DMG, McDonald GK, Cornish SM, Giesbrecht GG. Skin cooling on breath-hold duration and predicted emergency air supply duration during immersion. Aerosp Med Hum Perform. 2020; 91(7):578–585.

scholarly journals Lagged recovery of fish spatial distributions following a cold-water perturbation

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
M. D. Robertson ◽  
J. Gao ◽  
P. M. Regular ◽  
M. J. Morgan ◽  
F. Zhang
Keyword(s):  
Water Temperature ◽  
Species Distribution ◽  
Environmental Conditions ◽  
Cold Water ◽  
Heat Waves ◽  
Rapid Change ◽  
Nonlinear Effects ◽  
Spatial Distributions ◽  
Spatiotemporal Model ◽  
Yellowtail Flounder

AbstractAnomalous local temperature and extreme events (e.g. heat-waves) can cause rapid change and gradual recovery of local environmental conditions. However, few studies have tested whether species distribution can recover following returning environmental conditions. Here, we tested for change and recovery of the spatial distributions of two flatfish populations, American plaice (Hippoglossoides platessoides) and yellowtail flounder (Limanda ferruginea), in response to consecutive decreasing and increasing water temperature on the Grand Bank off Newfoundland, Canada from 1985 to 2018. Using a Vector Autoregressive Spatiotemporal model, we found the distributions of both species shifted southwards following a period when anomalous cold water covered the northern sections of the Grand Bank. After accounting for density-dependent effects, we observed that yellowtail flounder re-distributed northwards when water temperature returned and exceeded levels recorded before the cold period, while the spatial distribution of American plaice has not recovered. Our study demonstrates nonlinear effects of an environmental factor on species distribution, implying the possibility of irreversible (or hard-to-reverse) changes of species distribution following a rapid change and gradual recovery of environmental conditions.

scholarly journals Influence of Various Factors on Caffeine Content in Coffee Brews

Foods ◽  
2021 ◽  
Vol 10 (6) ◽  
pp. 1208
Author(s):  
Ewa Olechno ◽  
Anna Puścion-Jakubik ◽  
Małgorzata Elżbieta Zujko ◽  
Katarzyna Socha
Keyword(s):  
Literature Review ◽  
Water Temperature ◽  
Geographical Origin ◽  
Cold Water ◽  
Water Type ◽  
Robusta Coffee ◽  
Caffeine Content ◽  
Type Water ◽  
Brewing Time ◽  
Coffee Brews

Coffee brews are one of the most popular drinks. They are consumed for caffeine and its stimulant properties. The study aimed to summarize data on the influence of various factors on caffeine content in brews prepared with different methods. The study was carried out using a literature review from 2010–2020. PubMed and Google Scholar databases were searched. Data on caffeine content was collected by analyzing the following factors: the influence of species, brewing time, water temperature, pressure, degree of roast, grinding degree, water type, water/coffee ratio as well as other factors (such as geographical origin). To sum up, converting caffeine content to 1 L of the brew, the highest content is that of brews prepared in an espresso machine (portafilter), with the amount of 7.5 g of a coffee blend (95% Robusta + 5% Arabica), and water (the volume of coffee brew was 25 mL) at a temperature of 92 °C and a pressure of 7 bar, but the highest content in one portion was detected in a brew of 50 g of Robusta coffee poured with 500 mL of cold water (25 °C) and boiled.

scholarly journals Combined Effects of Summer Water Temperature and Current Velocity on the Distribution of a Cold-Water-Adapted Sculpin (Cottus nozawae)

Water ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 975
Author(s):  
Kaiji Suzuki ◽  
Nobuo Ishiyama ◽  
Itsuro Koizumi ◽  
Futoshi Nakamura
Keyword(s):  
Water Temperature ◽  
Climate Warming ◽  
Current Velocity ◽  
Cold Water ◽  
Environmental Gradients ◽  
Combined Effect ◽  
Influential Factor ◽  
Combined Effects ◽  
River Catchment ◽  
Water Abstraction

Clarifying the combined effects of water temperature and other environmental factors on the species distributions of cold-water fishes is the first step toward obtaining a better understanding of the complex impacts of climate warming on these species. In the present study, we examined the abundance and occurrence of the fluvial sculpin, Cottus nozawae, in response to water temperature along environmental gradients in northern Japan. The abundance survey was conducted in the Sorachi River catchment with two-pass electrofishing with a backpack electrofisher. For the occurrence survey, we carried out one-pass electrofishing in the Sorachi, Chitose, and Tokachi River catchments. Fish sampling was conducted once from July to August 2018 in the Sorachi River catchment, from May to June 2011 in the Chitose River catchment, and from July to September 2012 in the Tokachi River catchment. Generalized linear mixed models (GLMMs) and generalized linear models (GLMs) were used for the abundance and occurrence analyses, respectively. We found that the mean summer water temperature was the most influential factor on the distribution of C. nozawae; the abundance and occurrence were both negatively affected by increased water temperatures. In the occurrence model, occurrence probabilities of 0.9 and 0.5 for C. nozawae corresponded to mean summer temperatures of 12.0 and 16.1 °C, respectively. Furthermore, we identified a combined effect of water temperature and current velocity on the abundance of C. nozawae. The increased mean summer water temperature had a stronger negative effect on C. nozawae abundance under gentle flow conditions. While the precise mechanisms of this combined effect could not be determined in this study, stressors associated with low current velocities may increase their vulnerability to higher water temperatures. Our findings indicate that flow disturbances caused by human activities such as excessive water abstraction may exacerbate the negative impacts of climate warming on populations of C. nozawae in the future.

scholarly journals Fluctuating temperature of the mains water throughout the year and its influence on the consumption of energy for the purposes of DHW preparation

2018 ◽  
Vol 44 ◽  
pp. 00017 ◽  
Author(s):  
Agnieszka Chmielewska
Keyword(s):  
Water Treatment ◽  
Water Temperature ◽  
Cold Water ◽  
Treatment Plant ◽  
Water Treatment Plant ◽  
Monthly Basis ◽  
New Model ◽  
Water Influence ◽  
Family Building ◽  
Cold Water Temperature

The article discusses the influence of the cold water temperature on the amount of energy consumed for the purposes of the DHW preparation in multi-family buildings. The article begins with a presentation of the DHW consumption readings from a multi-family building, recorded on a monthly basis during the period of 4 years. The readings constituted the base for calculating the demand for energy for the purposes of the DHW preparation. Subsequently, basing on the output water temperature readings from the water treatment plant, it was proved that the temperature of the mains water fluctuates throughout the year. The review of the available literature, as well as the measurements, confirmed that it is necessary to develop a new model of the cold water temperature that would take into account the type of intake in a water treatment plant. The final part of the article presents how the accepted assumptions about the temperature of the mains water influence the consumption of energy for the purposes of the DHW preparation.

Skinfolds and resting heat loss in cold air and water: temperature equivalence

1975 ◽  
Vol 39 (1) ◽  
pp. 93-102 ◽  
Author(s):  
R. M. Smith ◽  
J. M. Hanna
Keyword(s):  
Heat Transfer ◽  
Water Temperature ◽  
Heat Loss ◽  
Air Temperature ◽  
Indirect Calorimetry ◽  
Cold Water ◽  
Heat Conductance ◽  
Air Temperatures ◽  
Body Core ◽  
Male Subjects

Fourteen male subjects with unweighted mean skinfolds (MSF) of 10.23 mm underwent several 3-h exposures to cold water and air of similar velocities in order to compare by indirect calorimetry the rate of heat loss in water and air. Measurements of heat loss (excluding the head) at each air temperature (Ta = 25, 20, 10 degrees C) and water temperature (Tw = 29–33 degrees C) were used in a linear approximation of overall heat transfer from body core (Tre) to air or water. We found the lower critical air and water temperatures to fall as a negative linear function of MSF. The slope of these lines was not significantly different in air and water with a mean of minus 0.237 degrees C/mm MSF. Overall heat conductance was 3.34 times greater in water. However, this value was not fixed but varied as an inverse curvilinear function of MSF. Thus, equivalent water-air temperatures also varied as a function of MSF. Between limits of 100–250% of resting heat loss the followingrelationships between MSF and equivalent water-air temperatures were found (see article).

scholarly journals HUBUNGAN KEPADATAN IKAN DENGAN KONDISI LINGKUNGAN PERAIRAN ESTUARI DI KABUPATEN BANYUASIN

2017 ◽  
Vol 23 (2) ◽  
pp. 111
Author(s):  
Aroef Hukmanan Rais ◽  
Rupawan Rupawan ◽  
Herlan Herlan
Keyword(s):  
Water Temperature ◽  
Significant Contribution ◽  
Aurelia Aurita ◽  
Total Biomass ◽  
Biomass Distribution ◽  
Phytoplankton Abundance ◽  
Biomass Density ◽  
Fish Resources ◽  
Salinity Water ◽  
Distribution Of Fish

Estuari di wilayah Kabupaten Banyuasin dengan potensi biodiversitas sumber daya ikan yang tinggi, merupakan wilayah penangkapan yang potensial dan berkontribusi besar terhadap poduksi perikanan Provinsi Sumatera Selatan. Distribusi biomassa sumber daya ikan di wilayah estuari sangat dinamis dan dipengaruhi oleh parameter salinitas dan suhu perairan pada suatu lingkungan perairan. Penelitian ini bertujuan untuk mengetahui kondisi kepadatan biomassa ikan dalam hubungannya dengan kondisi lingkungan perairan di wilayah perairan estuari Kabupaten Banyuasin.Pengambilan sampel ikan dilakukan dengan percobaan penangkapan menggunakan alat tangkap trawl mini yang diopeasikan di tiga wilayah estuari yaitu Sungai Banyuasin, Sungai Musi dan Sungai Upang. Pada masing-masing wilayah estuari ditentukan sebanyak empat lokasi sampling. Frekuensi pengambilan sampel dilakukan sebanyak empat kali yaitu pada Maret, Juni, Agustus dan Oktober agar mewakili kondisi musiman.Parameter lingkungan yang dianalisa adalah salinitas, suhu perairan, kecerahan, nitrat, amoniak, total fosfat dan kelimpahan fitoplankton. Hasil penelitian menunjukkan sebanyak 87 spesies ikan telah teridentifikasi. Diperoleh nilai kepadatan biomassa 332,13 – 861,49 kg/km2 di estuari Upang, 590,51 – 2.235,04 kg/km2 di estuari Musi dan 1.296,4 - 33.714,88 kg/km2 di estuari Banyuasin. Spesies ubur-ubur (Aurelia aurita) mendominasi tangkapan pada Agustus hingga Oktober yang mencapai 77,22% dari biomassa total ikan dikarenakan lingkungan yang sesuai untuk keperluan pertumbuhannya. Kepadatan biomassa ikan berkorelasi positif dengan parameter salinitas dan kelimpahan fitoplankton, dan berkorelasi negatif terhadap parameter amoniak. Estuaries of Banyuasin district has a high biodiversity of fish resources and significant contribution to the fisheries production in the South Sumatera Province. The biomass distribution of fish in the estuary fluctuated and probably affected by by salinity and water temperature. This research aims to investigate the correlation between biomass density and environment condition in the estuary of Banyuasin Regency. Sampling was conducted through experimental fishing used a mini trawl that operated in three estuary areas, such as: Banyuasin Rivers, Musi Rivers, and Upang Rivers. Every estuary area was replicated for four sampling sites. Samples were collected during March, June, August and October. The waters parameters analyzed were salinity, water temperature, transparency, nitrate, ammonia, phosphate total, and phytoplankton. The results showed that about 87 species of fish have been identified. The biomass density was 332,13 – 861,49 kg/km2 in estuary Upang, 590,51 – 2.235,04 kg/km2 in estuary Musi and 1.296,4 - 33.714,88 kg/km2 in estuari Banyuasin. A jelly fish (Aurelia aurita) is dominated in August to October, up to 77.22% of total biomass. The biomass density of fish was positively correlated with salinity and phytoplankton abundance, whereas negatively correlated to ammoniac condition.

Diving and swimming performance of white whales, Delphinapterus leucas: an assessment of plasma lactate and blood gas levels and respiratory rates.

1997 ◽  
Vol 200 (24) ◽  
pp. 3091-3099 ◽  
Author(s):  
S A Shaffer ◽  
D P Costa ◽  
T M Williams ◽  
S H Ridgway
Keyword(s):  
High Speed ◽  
Swimming Performance ◽  
Lactate Concentration ◽  
Delphinapterus Leucas ◽  
Breath Hold ◽  
Plasma Lactate ◽  
Post Exercise ◽  
Test Platform ◽  
Plasma Lactate Concentration ◽  
Breath Hold Duration

The white whale Delphinapterus leucas is an exceptional diver, yet we know little about the physiology that enables this species to make prolonged dives. We studied trained white whales with the specific goal of assessing their diving and swimming performance. Two adult whales performed dives to a test platform suspended at depths of 5-300 m. Behavior was monitored for 457 dives with durations of 2.2-13.3 min. Descent rates were generally less than 2 m s-1 and ascent rates averaged 2.2-3 m s-1. Post-dive plasma lactate concentration increased to as much as 3.4 mmol l-1 (4-5 times the resting level) after dives of 11 min. Mixed venous PO2 measured during voluntary breath-holds decreased from 79 to 20 mmHg within 10 min; however, maximum breath-hold duration was 17 min. Swimming performance was examined by training the whales to follow a boat at speeds of 1.4-4.2 m s-1. Respiratory rates ranged from 1.6 breaths min-1 at rest to 5.5 breaths min-1 during exercise and decreased with increasing swim speed. Post-exercise plasma lactate level increased to 1.8 mmol l-1 (2-3 times the resting level) following 10 min exercise sessions at swimming speeds of 2.5-2.8 m s-1. The results of this study are consistent with the calculated aerobic dive limit (O2 store/metabolic rate) of 9-10 min. In addition, white whales are not well adapted for high-speed swimming compared with other small cetaceans.

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