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The American Heart Association (AHA; Dallas, Texas USA) and European Resuscitation Council (Niel, Belgium) cardiac arrest (CA) guidelines recommend the intraosseous (IO) route when intravenous (IV) access cannot be obtained. Vasopressin has been used as an alternative to epinephrine to treat ventricular fibrillation (VF).
Limited data exist on the pharmacokinetics and resuscitative effects of vasopressin administered by the humeral IO (HIO) route for treatment of VF. The purpose of this study was to evaluate the effects of HIO and IV vasopressin, on the occurrence, odds, and time of return of spontaneous circulation (ROSC) and pharmacokinetic measures in a swine model of VF.
Twenty-seven Yorkshire-cross swine (60 to 80 kg) were assigned randomly to three groups: HIO (n=9), IV (n=9), and a control group (n=9). Ventricular fibrillation was induced and untreated for two minutes. Chest compressions began at two minutes post-arrest and vasopressin (40 U) administered at four minutes post-arrest. Serial blood specimens were collected for four minutes, then the swine were resuscitated until ROSC or 29 post-arrest minutes elapsed.
Fisher’s Exact test determined ROSC was significantly higher in the HIO 5/7 (71.5%) and IV 8/11 (72.7%) groups compared to the control 0/9 (0.0%; P=.001). Odds ratios of ROSC indicated no significant difference between the treatment groups (P=.68) but significant differences between the HIO and control, and the IV and control groups (P=.03 and .01, respectively). Analysis of Variance (ANOVA) indicated the mean time to ROSC for HIO and IV was 621.20 seconds (SD=204.21 seconds) and 554.50 seconds (SD=213.96 seconds), respectively, with no significant difference between the groups (U=11; P=.22). Multivariate Analysis of Variance (MANOVA) revealed the maximum plasma concentration (Cmax) and time to maximum concentration (Tmax) of vasopressin in the HIO and IV groups was 71753.9 pg/mL (SD=26744.58 pg/mL) and 61853.7 pg/mL (SD=22745.04 pg/mL); 111.42 seconds (SD=51.3 seconds) and 114.55 seconds (SD=55.02 seconds), respectively. Repeated measures ANOVA indicated no significant difference in plasma vasopressin concentrations between the treatment groups over four minutes (P=.48).
The HIO route delivered vasopressin effectively in a swine model of VF. Occurrence, time, and odds of ROSC, as well as pharmacokinetic measurements of HIO vasopressin, were comparable to IV.
BurgertJM, JohnsonAD, Garcia-BlancoJ, FultonLV, LoughrenMJ. The Resuscitative and Pharmacokinetic Effects of Humeral Intraosseous Vasopressin in a Swine Model of Ventricular Fibrillation. Prehosp Disaster Med. 2017;32(3):305–310.
Obtaining intravenous (IV) access in patients in hemorrhagic shock is often difficult and prolonged. Failed IV attempts delay life-saving treatment. Intraosseous (IO) access may often be obtained faster than IV access. Albumin (5%) is an option for prehospital volume expansion because of the absence of interference with coagulation and platelet function.
There are limited data comparing the performance of IO and IV administered 5% albumin. The aims of this study were to compare the effects of tibial IO (TIO) and IV administration of 500 mL of 5% albumin on infusion time and hemodynamic measurements of heart rate (HR), mean arterial pressure (MAP), cardiac output (CO), and stroke volume (SV) in a swine model of hemorrhagic shock.
Sixteen male swine were divided into two groups: TIO and IV. All subjects were anesthetized and a Class III hemorrhage was achieved by exsanguination of 31% of estimated blood volume (EBV) from a femoral artery catheter. Following exsanguination, 500 mL of 5% albumin was administered under pressurized infusion (300 mmHg) by the TIO or IV route and infusion time was recorded. Hemodynamic measurements of HR, MAP, CO, and SV were collected before and after exsanguination and every 20 seconds for 180 seconds during 5% albumin infusion.
An independent t-test determined that IV 5% albumin infusion was significantly faster compared to IO (P=.01). Mean infusion time for TIO was seven minutes 35 seconds (SD=two minutes 44 seconds) compared to four minutes 32 seconds (SD=one minute 08 seconds) in the IV group. Multivariate Analysis of Variance was performed on hemodynamic data collected during the 5% albumin infusion. Analyses indicated there were no significant differences between the TIO and IV groups relative to MAP, CO, HR, or SV (P>.05).
While significantly longer to infuse 5% albumin by the TIO route, the longer TIO infusion time may be negated as IO devices can be placed more quickly compared to repeated IV attempts. The lack of significant difference between the TIO and IV routes relative to hemodynamic measures indicate the TIO route is a viable route for the infusion of 5% albumin in a swine model of Class III hemorrhage.
MuirSL, SheppardLB, Maika-WilsonA, BurgertJM, Garcia-BlancoJ, JohnsonAD, CoynerJL. A Comparison of the Effects of Intraosseous and Intravenous 5% Albumin on Infusion Time and Hemodynamic Measures in a Swine Model of Hemorrhagic Shock. Prehosp Disaster Med.2016;31(4):436–442.
Abundant fossil plant remains are preserved in the high-latitude middle Eocene deposits of the Buchanan Lake Formation on Axel Heiberg Island, Nunavut Territory, Canada. Intact leaf litter, logs, and stumps preserved in situ as mummified remains offer an opportunity to determine the structure, biomass, and productivity of two Taxodiaceae-dominated forests that grew north of the Arctic Circle (paleolatitude 75–80°N). We excavated fossil tree trunks and treetops to develop equations that describe the height, structure, and mass of the aboveground components of Eocene-age Metasequoia trees. We combined those data with surveys of in situ stumps to determine the structure, biomass, and productivity of two fossil forests, “N” and “HR.” We calculated a canopy height of 40 ± 3 m for the N forest and 25 m ± 2 m for the HR forest. Buried knots in dissected logs and abundant branch-free bole wood indicate that these were tall, closed-canopy forests. Stem tapers indicate that the overstory was of uniform height. Stem volume equaled 2095 m3 ha−1 and stem biomass was 628 Mg ha−1 in the N forest. Volume and biomass in the HR forest were much smaller, 211 m3 ha−1 and 63.3 Mg ha−1, respectively. We estimated understory tree biomass to be 40 Mg ha−1 in the N forest and 3.5 Mg ha−1 in the HR forest. Recovery of seven fossil treetops with exposed branch stubs enabled us to make estimates of branchwood and foliar biomass using allometric equations derived from modern, plantation-grown Metasequoia glyptostroboides. Estimated stand-level branch biomass was 13 and 6.7 Mg ha−1 in the N and HR forests, respectively. Standing foliar biomass was estimated to be 3.2 and 2.1 Mg ha−1 in the N and HR forests, respectively. Using annual ring widths, the reconstructed parabolic stems, and wood density of modern Metasequoia, we calculated annual wood production to be 2.3 Mg ha−1 yr−1 for the N forest and 0.55 Mg ha−1 yr−1 for the HR forest Assuming that the ancient Metasequoia were deciduous like their living relatives, annual aboveground net primary productivity was 5.5 Mg ha−1 yr−1 for the N forest and 2.8 Mg ha−1 yr−1 for the HR forest. Our estimated biomass and productivity values for N are similar to those of modern old-growth forests of the Pacific Northwest of the United States and old-growth coastal Cordillera forests of southern Chile.
Accurate reconstruction of the biomass, structure, and productivity of ancient forests from their fossilized remnants remains an interesting challenge in paleoecology. In well-preserved Tertiary fossil Metasequoia forests of Canada's Arctic, in situ stumps and fragments of stems, treetops, and branches contain substantial information about tree dimensions that can be used to determine tree height, stand biomass, and other characteristics such as canopy depth and structure, and the history of stand development. To validate a method for reconstructing the biomass of the Eocene floodplain Metasequoia forests of Axel Heiberg Island, we measured stump diameters and spacing, and stem, branch, and treetop characteristics in living Metasequoia glyptostroboides and Chamaecyparis thyoides stands in ways that simulate the limited measurements that can be made in well-preserved fossil forests in Canada and probably elsewhere. We used those limited measurements to estimate tree height and volume, branch and foliar dry weights, and tree biomass. The estimates derived from the limited data set are usually within 15% of the estimates derived from the methods currently used in forest ecology for determining those metrics in modern forests. Under appropriate conditions, the biomass of ancient forests can be estimated with reasonable confidence.
An energy resource is the first step in the chain that supplies energy services (for a definition of energy services, see Chapter 1). Energy services are largely ignorant of the particular resource that supplies them; however, often the infrastructures, technologies, and fuels along the delivery chain are highly dependent on a particular type of resource. The availability and costs of bringing energy resources to the market place are key determinants to affordable and accessible energy services.
Energy resources pose no inherent limitation to meeting the rapidly growing global energy demand as long as adequate upstream investment is forthcoming – for exhaustible resources in exploration, production technology, and capacity (mining and field development) and, by analogy, for renewables in conversion technologies.
Hydrocarbons and Nuclear
Occurrences of hydrocarbons and fissile materials in the Earth's crust are plentiful – yet they are finite. The extent of the ultimately recoverable oil, natural gas, coal, or uranium is the subject of numerous reviews, yet still the range of values in the literature is large (Table 7.1). For example, the range for conventional oil is between 4900 exajoules (EJ) for reserves to 13,700 EJ (reserves plus resources) – a range that sustains continued debate and controversy. The large range is the result of varying boundaries of what is included in the analysis of a finite stock of an exhaustible resource, e.g., conventional oil only or conventional oil plus unconventional occurrences, such as oil shale, tar sands, and extra-heavy oils.
Thin films of the shape memory alloy NiTi have been sputter-deposited onto ptype silicon substrates. Films that are initially amorphous may be crystallized by vacuum annealing. The crystalline films exhibit the B2->B19′ phase change associated with the shape memory effect while remaining in contact with the silicon substrate. Transition temperatures were determined by resistance measurements and x-ray diffraction. The NiTi - Si contacts are diodes, as evidenced by their current-voltage characteristics; however, the effect of the phase change on the barrier height could not be determined.
On October 27–28, 1961, the Harvard Business History Group sponsored a conference devoted to the theme “Business History as a Teaching Challenge.” The purpose was simple enough — get experienced, active practitioners in business history together with newcomers to the field in the expectation that interaction between the two groups would be mutually beneficial. This hope was realized, though the specific results were somewhat different — and perhaps more valuable — than those originally anticipated. The 50 participants found themselves more involved with a discussion of the appropriate subject matter of business history, past accomplishments, and future possibilities, than with current teaching problems and techniques. This development was not totally unanticipated, but the enthusiasm with which it was embraced came as a pleasant surprise. It therefore seems appropriate to precede the papers given at the conference with a brief summary of the present status and future prospects of business history in the light of the discussion and the written comments later submitted by participants.
Some two years ago, the Editors of the Business History Review adopted a policy of preparing one special issue per year devoted to a significant topic or area in business history. The first such issue, covering fashion, appeared last year and met an enthusiastic reception. The present issue represents our second major effort to highlight problems and approaches to important areas of business history. In this instance the subject is government-business relations.
In this second special issue devoted to government-business relations, the focus is exclusively on the United States' experience, just as the Spring, 1964 issue concentrated solely on experience abroad. This approach is in keeping with the Editors' view that business history is international in scope, that there are virtues in comparative approaches to the subject, and that public authority has formed and will continue to form significant parameters for private business decision-making.