Effect of body hypothermia on transventricular simple-capacitor-discharge defibrillation thresholds

Arredondo, María Teresa; Armayor, M. R.; Clavin, O. E.; Valentinuzzi, Max E.; Scida, E. E.

doi:10.1152/ajpheart.1980.238.5.h675

Cited by 9 publications

(4 citation statements)

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“…This may be related in part to different experimental designs, modes of defibrillation, degree of hypothermia used, different animal species, and lack of statistics in one study. 23 Our finding of improved initial-shock defibrillation is similar to the findings of Arredondo et al, 24 who showed that body hypothermia reduced the transventricular (ie, open-chest model) defibrillation threshold. Unlike our findings, Tacker et al, 23 in a transthoracic defibrillation canine model, found that the defibrillation threshold energy requirement increased 2.5%/°C decrement of body temperature.…”

Section: Discussionsupporting

confidence: 88%

“…Other investigators also examined the effects of hypothermia on defibrillation. 16,23,24 The results of these investigators vary in their ability to demonstrate defibrillation efficacy in the setting of hypothermia. This may be related in part to different experimental designs, modes of defibrillation, degree of hypothermia used, different animal species, and lack of statistics in one study.…”

Section: Discussionmentioning

confidence: 99%

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Hypothermia Improves Defibrillation Success and Resuscitation Outcomes From Ventricular Fibrillation

et al. 2005

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Background-Induced hypothermia is recommended to improve neurological outcomes in unconscious survivors of out-of-hospital ventricular fibrillation (VF) cardiac arrest. Patients resuscitated from a VF arrest are at risk of refibrillation, but there are few data on the effects of already existing hypothermia on defibrillation and resuscitation. Methods and Results-Thirty-two swine (meanϮSE weight, 23.0Ϯ0.6 kg) were divided into 4 groups: normothermia (nϭ8), mild hypothermia (35°C) (nϭ8), moderate hypothermia (33°C) (nϭ8), and severe hypothermia (30°C) (nϭ8). Hypothermia was induced by surrounding the animal with ice, and VF was electrically induced. After 8 minutes of unsupported VF (no CPR), the swine were defibrillated (biphasic waveform) with successive shocks as needed and underwent CPR until resumption of spontaneous circulation or no response (Ն10 minutes). First-shock defibrillation success was higher in the moderate hypothermia group (6 of 8 hypothermia versus 1 of 8 normothermia; Pϭ0.04). The number of shocks needed for late defibrillation (Ն1 minute after initial shock) was less in all 3 hypothermia groups compared with normothermia (all PϽ0.05). None of the 8 animals in the normothermia group achieved resumption of spontaneous circulation compared with 3 of 8 mild hypothermia (PϭNS), 7 of 8 moderate hypothermia (Pϭ0.001), and 5 of 8 severe hypothermia (Pϭ0.03) animals. Coronary perfusion pressure during CPR was not different between the groups. Conclusions-When VF was induced in the setting of moderate or severe hypothermia, resuscitative measures were facilitated with significantly improved defibrillation success and resuscitation outcome. The beneficial effect of hypothermia was not due to alteration of coronary perfusion pressure, which suggests that changes in the mechanical, metabolic, or electrophysiological properties of the myocardium may be responsible.

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Section: Discussionsupporting

confidence: 88%

Section: Discussionmentioning

confidence: 99%

Hypothermia Improves Defibrillation Success and Resuscitation Outcomes From Ventricular Fibrillation

et al. 2005

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“…The obtained data were analyzed using a statistical package (Cohort software, Costat V6.303) to work out analysis of variance. LSD (least significance difference) test was used to compare the means of all treatments following Snedecor and Cochran [ 49 ].…”

Section: Methodsmentioning

confidence: 99%

Sugar beet extract rich in glycine betaine modulates oxidative defense system and key physiological characteristics of maize under water-deficit stress

et al. 2021

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Now-a-days, plant-based extracts, as a cheap source of growth activators, are being widely used to treat plants grown under extreme climatic conditions. So, a trial was conducted to assess the response of two maize (Zea mays L.) varieties, Sadaf (drought tolerant) and Sultan (drought sensitive) to foliar-applied sugar beet extract (SBE) under varying water-deficit conditions. Different SBE (control, 1%, 2%, 3% & 4%) levels were used in this study, and plants were exposed to water-deficit [(75% and 60% of field capacity (FC)] and control (100% FC) conditions. It was observed that root and shoot dry weights (growth), total soluble proteins, RWC-relative water contents, total phenolics, chlorophyll pigments and leaf area per plant decreased under different water stress regimes. While, proline, malondialdehyde (MDA), RMP-relative membrane permeability, H2O2-hydrogen peroxide and the activities of antioxidant enzymes [CAT-catalase, POD-peroxidase and SOD-superoxide dismutase] were found to be improved in water stress affected maize plants. Exogenous application of varying levels of SBE ameliorated the negative effects of water-deficit stress by enhancing the growth attributes, photosynthetic pigments, RWC, proline, glycinebetaine (GB), activities of POD and CAT enzymes and levels of total phenolics, whereas it reduced the lipid peroxidation in both maize varieties under varying water stress levels. It was noted that 3% and 4% levels of SBE were more effective than the other levels used in enhancing the growth as well as other characteristics of the maize varieties. Overall, the sugar beet extract proved to be beneficial for improving growth and metabolism of maize plants exposed to water stress.

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“…The normality of the data was determined using the Shapiro-Wilk test (PROC UNIVARIATE). Mortality rates that did not fit a normal distribution were arcsine transformed prior to analyses [40]. The Bonferroni correction was applied to examine differences among treatments (PROC MIXED).…”

Section: Statistical Analysesmentioning

confidence: 99%

New bioassay cage methodology for in vitro studies on Varroa destructor and Apis mellifera

Bahreini¹,

Nasr²,

Docherty³

et al. 2021

PLoS ONE

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Varroa destructor Anderson and Trueman, is an ectoparasitic mite of honey bees, Apis mellifera L., that has been considered a major cause of colony losses. Synthetic miticides have been developed and registered to manage this ectoparasite, however, resistance to registered pyrethroid and organophosphate Varroacides have already been reported in Canada. To test toxicity of miticides, current contact-based bioassay methods are designed to evaluate mites and bees separately, however, these methods are unlikely to give an accurate depiction of how miticides interact at the colony level. Therefore, the objective of this study was to develop a bioassay cage for testing the toxicity of miticides on honey bees and Varroa mites simultaneously using amitraz as a reference chemical. A 800 mL polypropylene plastic cage holding 100–150 bees was designed and officially named “Apiarium”. A comparison of the effects of three subsequent dilutions of amitraz was conducted on: Varroa mites placed in glass vials, honey bees in glass Mason jars, and Varroa-infested bees in Apiariums. Our results indicated cumulative Varroa mortality was dose-dependent in the Apiarium after 4 h and 24 h assessments. Apiarium and glass vial treatments at 24 h also had high mite mortality and a positive polynomial regression between Varroa mortality and amitraz dose rates. Moreover, chemical application in the Apiarium was less toxic for bees compared to the Mason jar method. Considering these results, the Apiarium bioassay provides a simple, cheap and reliable method for simultaneous chemical screening on V. destructor and A. mellifera. Furthermore, as mites and bees are tested together, the Apiarium simulates a colony-like environment that provides a necessary bridge between laboratory bioassay testing and full field experimentation. The versatility of the Apiarium allows researchers to test a multitude of different honey bee bioassay experiments including miticide screening, delivery methods for chemical products, or development of new mite resistance-testing methodology.

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Effect of body hypothermia on transventricular simple-capacitor-discharge defibrillation thresholds

Cited by 9 publications

References 0 publications

Hypothermia Improves Defibrillation Success and Resuscitation Outcomes From Ventricular Fibrillation

Hypothermia Improves Defibrillation Success and Resuscitation Outcomes From Ventricular Fibrillation

Sugar beet extract rich in glycine betaine modulates oxidative defense system and key physiological characteristics of maize under water-deficit stress

New bioassay cage methodology for in vitro studies on Varroa destructor and Apis mellifera

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