Intraosseous infusion devices: a comparison for potential use in special operations.

OBJECTIVE: To determine which intraosseous (IO) devices were easy to learn to use, easy to use once the skill was obtained, and appropriate for the Special Operations environment. METHODS: Thirty-one Navy SEAL corpsmen, Air Force pararescuemen, Army Special Forces, and Ranger medics, in a prospective, randomly assigned, cross-over study, tested four commercially available, Food and Drug Administration-cleared IO devices. The systems included the injection models First Access for Shock and Trauma (FAST, Pyng Medical) and Bone Injection Gun (Wais Medical, Kress USA Corporation) and the hand-driven threaded-needle SurFast (Cook Critical Care) and straight-needle Jamshidi needle (Baxter) models. The Special Operations medical care providers received a lecture regarding IO use, viewed videotapes of the injection models, and practiced with demonstration units in the classroom. Each participant then entered the cadaver lab where all four of the IO devices were placed in randomly assigned order. A poststudy questionnaire was then completed. The FAST was placed in the sternum, whereas the other units were placed in either medial proximal or distal medial tibia. Each participant was assessed for time, number of attempts, and success. The presence of marrow, extravasation, quality of flow, and security of needle were evaluated in combination to help determine success. RESULTS: All four devices were believed to be easy to learn as well as easy to place. FAST was successful in 29 of 30 insertions (94%) with a placement time of 114 +/- 36 (mean +/- SD) seconds. The Bone Injection Gun was similarly successful (29 of 31 insertions, 94%) with a mean placement time of 70 +/- 33 seconds. This time was statistically significantly faster (p < 0.05) than that with FAST, but not with the other devices. Thirty of 31 SurFast placements (97%) were successful, on average taking 88 +/- 33 seconds to place. The Jamshidi needle also had 30 of 31 successful placements (97%) at an average 90 +/- 59 seconds. No one device was rated by the participants as significantly better than the others; however, the Bone Injection Gun did have 65% of participants rate it as first or second (closest was Jamshidi needle at 52%). CONCLUSION: These IO devices were easy to teach and learn as well as easy to use. Insertion times compared favorably with peripheral intravenous catheter placement in the face of hemorrhage. All four devices can be appropriately used in the Special Operations environment and are reasonable alternatives when intravenous access cannot be gained. Although no device was rated higher than the others, particular features are desirable (low weight/size, simplicity, reusability, secure, clean, well protected).

Evaluation of possible battlefield tourniquet systems for the far-forward setting.

A significant number of casualties in previous conflicts died from peripheral vascular wounds. A well-designed tourniquet could possibly have prevented these deaths. The objective of this study was the identification of such a tourniquet. A survey of Special Operations corpsmen established important characteristics necessary in an ideal tourniquet. Because most available devices do not and patented ideas could not meet these criteria, a number of prototypes were developed. Seven potentially satisfactory tourniquets were evaluated by 15 Navy SEAL corpsmen. The success and timing of placement were recorded, and a follow-up questionnaire was completed. Of the several successful tourniquets, two were preferred. Tourniquets incorporating a windlass technique take longer to place and often fail when placed with only one hand. New, relatively simple tourniquet devices incorporating bladder and ratchet mechanisms can significantly improve tourniquet performance.

Influence of temperature on oxygen diffusion in hamster retractor muscle.

A mathematical analysis by Popel et al. [Am. J. Physiol. 256 (Heart Circ. Physiol. 25): H921-H924, 1989] of in vivo data on arteriolar O2 loss suggested that Krogh's diffusion coefficient (KO2 = alpha x DO2, where DO2 is the O2 diffusion coefficient and alpha is the tissue O2 solubility) in vivo could be an order of magnitude larger than that calculated from DO2 values measured in vitro at 22 degrees C and extrapolated to 37 degrees C. In this study, to eliminate potential extrapolation errors, we used a miniature hyperbaric chamber with 1-2 atm of O2 to maintain tissue oxygenation and allow DO2 measurements directly at 37 degrees C while using a non-steady-state technique. The need for metabolic poisons that had been required by earlier experimental techniques was thereby eliminated. DO2 measured directly at 37 degrees C (2.42 x 10(-5) cm2/s) and the increase with temperature of DO2 between 30 and 41 degrees C (4.61%/degrees C) were unexpectedly higher than the values we found at lower temperatures. Oxygen consumption was also higher than expected at 37 degrees and 40 degrees C. An analysis of the activation energy for DO2 suggests that at higher temperatures there is a change in the diffusion pathway from that existing at lower temperatures, perhaps caused by phase transitions in the lipid membranes.

Distribution and role of lipopolysaccharide in the pathogenesis of acute renal proximal tubule injury.

Endotoxins (lipopolysaccharides; LPS) are known to cause multiple organ failure, including renal dysfunction. The present report elucidates LPS distribution and effect on renal proximal tubules in an attempt to gain a better understanding of the cellular mechanism underlying the pathogenesis of renal dysfunction in endotoxemia and sepsis. Rats were intravenously treated with biotin-linked or regular Escherichia coli (0111:B4) LPS (3 mg/kg) and sacrificed at different times. Kidneys were retrieved and examined for LPS localization, tubular permeability, ultracytochemical alterations, leukocyte sequestration, and ICAM-1 expression. The functional impact of endotoxemia was also assessed by monitoring the changes in urine levels of glucose in timed collections up to 6 h. LPS was localized on the plasma membranes of the apical microvilli, the labyrinth of the lateral intercellular spaces, in various organelles of epithelial cells, and in the endothelial cells of the peritubular capillaries. LPS caused structural damage and calcium accumulation in the mitochondria, leakage of tight junctions, widening of the basolateral intercellular spaces, intracellular and extracellular edema, leukocyte margination and accumulation, vascular expression of ICAM-1, and decrease of plasma membrane and mitochondrial Ca2(+)-ATPase. Physiological study showed that both urine volume and glucose were greatly increased after LPS infusion. The pathological alterations in the proximal tubules may directly contribute to the reduction in the reabsorption ability of the proximal tubules.

Temperature dependence of oxygen diffusion and consumption in mammalian striated muscle.

This study investigated the effect of temperature on the oxygen diffusion coefficient (DO2) of hamster retractor muscle from 11 to 37 degrees C. DO2 was measured using a non-steady-state technique, whereas muscle O2 consumption (VO2) was estimated after steady state was reached. DO2 was 0.84 +/- 0.04 x 10(-5) cm2/s at 11 degrees C and rose exponentially to 2.41 +/- 0.19 x 10(-5) cm2/s at 37 degrees C, producing a temperature coefficient for DO2 of 4.60%/degrees C for this temperature range. To measure DO2 directly at 37 degrees C, it was necessary to inhibit tissue VO2 with Amytal. The DO2 measurements made at 37 degrees C were significantly higher than previously reported values, which had been based on extrapolations from lower temperatures (6). Further analysis suggests a possible transition in the diffusion pathway between 23 and 30 degrees C, resulting in a DO2 higher than that previously expected. This larger DO2, together with a recently published value of oxygen solubility (alpha) (21), results in an in vitro Krogh's diffusion coefficient (KO2) that is 2.4 times larger than that previously reported (24) and therefore significantly reduces an order of magnitude discrepancy between in vitro and estimated in vivo KO2 values (24). Muscle VO2 was 0.35 ml O2.min-1.100 g-1 at 11 degrees C and increased with temperature, resulting in an activation energy of the rate-limiting reaction from the Arrhenius equation of -10.5 kcal/mol between 11 and 30 degrees C.

Myoglobin content of hamster skeletal muscles.

Myoglobin (Mb) may facilitate O2 diffusion in muscle tissue, yet models of O2 transport are often simplified by ignoring the role of Mb. A recent analysis of O2 transport in hamster retractor muscle revealed a large discrepancy between the observed O2 diffusion from arterioles and that predicted by a mathematical model that did not include Mb. To establish whether this simplification was justified, we measured Mb content ([Mb]) in three hamster muscles that vary markedly in histochemical fiber type composition. [Mb] was determined spectrophotometrically using freshly excised tissues from hamsters of different ages (5-34 wk). [Mb] increased rapidly up to 15 wk of age and then rose more slowly. [Mb] in hamster muscles paralleled oxidative capacity. Our measurements of rat and dog muscles also show that [Mb] varies greatly among species and among muscles of a given species. The results indicate that in the hamster the variability in [Mb] with age and muscle should be taken into account when the potential role of Mb in studies on O2 transport is interpreted.

Oxygen diffusion in hamster striated muscle: comparison of in vitro and near in vivo conditions.

To investigate the suggestion of A. S. Popel, R. N. Pittman, and M. L. Ellsworth [Am. J. Physiol. 256 (Heart Circ. Physiol. 25): H921-H924, 1989] that Krogh's diffusion coefficient for O2 in vivo might be an order of magnitude higher than in vitro, O2 diffusion coefficient (DO2) and resting O2 consumption were measured on hamster retractor muscle in vitro and under near in vivo conditions where the muscle remained attached to the animal but the arterial inflow was occluded just before measurement. Experiments were performed on two groups of animals, differing in weight and age. We found that DO2 determined in vitro (extrapolated to 37 degrees C) was 1.81 +/- 0.12 x 10(-5) cm2/s for group I (smaller and younger), which was not significantly different from the value (2.00 +/- 0.08 x 10(-5) cm2/s) determined in group II. In both groups, DO2 under near in vivo conditions tended to be 10-15% larger than the value in vitro, although this trend did not reach statistical significance. It is unlikely that this trend is large enough to reconcile the inconsistency between theoretical and experimental determinations of O2 diffusion from the arteriolar network of this tissue.

Cell-mediated immune response of Chelonia mydas.

Blastogenic and cytotoxic responsiveness of peripheral blood leukocytes from the green turtle, Chelonia mydas were examined. Blastogenic responses were low level and showed considerable variation between animals. Blastogenesis in response to phytohemagglutinin and concanavalin A was observed through out all seasons. Responses to pokeweed mitogen and lipopolysaccharide were seasonal, appearing in spring. No blastogenic response to protein A or allogeneic leukocytes was observed. Cytotoxic responses to phytohemagglutinin and antibody-dependent cell-mediated cytotoxicity were of significant magnitude and, all animals responded in a similar manner. No spontaneous cytotoxic reactivity was observed.