Timothy B. Bentley

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).

Mathematical modeling of posthemorrhage inflammation in mice: studies using a novel, computer-controlled, closed-loop hemorrhage apparatus.

Hemorrhagic shock (HS) elicits a global acute inflammatory response, organ dysfunction, and death. We have used mathematical modeling of inflammation and tissue damage/dysfunction to gain insight into this complex response in mice. We sought to increase the fidelity of our mathematical model and to establish a platform for testing predictions of this model. Accordingly, we constructed a computerized, closed-loop system for mouse HS. The intensity, duration, and time to achieve target MAP could all be controlled using a software. Fifty-four male C57/black mice either were untreated or underwent surgical cannulation. The cannulated mice were divided into 8 groups: (a) 1, 2, 3, or 4 h of surgical cannulation alone and b) 1, 2, 3, or 4 h of cannulation + HS (25 mmHg). MAP was sustained by the computer-controlled reinfusion and withdrawal of shed blood within ±2 mmHg. Plasma was assayed for the cytokines TNF, IL-6, and IL-10 as well as the NO reaction products NO2−/NO3−. The cytokine and NO2−/NO3− data were compared with predictions from a mathematical model of post-hemorrhage inflammation, which was calibrated on different data. To varying degrees, the levels of TNF, IL-6, IL-10, and NO2−/NO3− predicted by the mathematical model matched these data closely. In conclusion, we have established a hardware/software platform that allows for highly accurate, reproducible, and mathematically predictable HS in mice.ABBREVIATIONS-HS-hemorrhagic shock; HR-heart rate

Hemorrhagic Shock in Swine: Nitric Oxide and Potassium Sensitive Adenosine Triphosphate Channel Activation

Background:To determine the role of nitric oxide and adenosine triphosphate–sensitive potassium (KATP) vascular channels in vascular decompensation during controlled hemorrhagic shock in swine. Methods:Thirty instrumented, anesthetized adolescent Yorkshire swine were subjected to controlled isobaric hemorrhage to a mean arterial pressure of 40 mmHg for 2 h (n = 6) or 4 h (n = 10) or 50 mmHg for 4 h (n = 8). An additional six animals were used as anesthetized instrumented time controls. During controlled hemorrhage, plasma and tissue samples were obtained every 30 to 60 min. Before euthanasia, tissue (carotid artery, lung, liver, and aorta) was obtained for analysis of nitrate concentrations and nitric oxide synthase activity. Isolated carotid artery ring reactivity to norepinephrine was also determined with and without glibenclamide. Results:Animals hemorrhaged to 40 mmHg decompensated earlier than animals hemorrhaged to 50 mmHg. Plasma nitrate concentrations and nitric oxide synthase activity rose consistently throughout hemorrhage in both groups. However, they were substantially higher in the mean arterial pressure 40 group. Constitutive nitric oxide synthase activity was the major contributor to total nitric oxide synthase activity throughout the protocol with only the animals maintained at 40 mmHg for 4 h showing evidence of inducible nitric oxide synthase activity. Profound KATP channel activation and hyporeactivity of isolated vessel rings to norepinephrine was not observed until 4 h after the initiation of hemorrhagic shock. Only those animals with inducible nitric oxide synthase activity showed a decreased response to norepinephrine, and this hyporeactivity was reversed with the KATP channel inhibitor, glibenclamide. Conclusions:The data indicate that profound KATP activation associated with increased nitric oxide concentrations and inducible nitric oxide synthase induction is a key factor in vascular smooth muscle hyporeactivity characteristic of the late decompensatory phase of hemorrhagic shock in swine.

Pulmonary (cardio) diagnostic system for combat casualty care capable of extracting embedded characteristics of obstructive or restrictive flow

Walter Reed Army Institute of Research and Oak Ridge National Laboratory have developed a prototype pulmonary diagnostic system capable of extracting signatures from adventitious lung sounds that characterize obstructive and/or restrictive flow. Examples of disorders that have been detailed include emphysema, asthma, pulmonary fibrosis, and pneumothorax. The system is based on the premise that acoustic signals associated with pulmonary disorders can be characterized by a set of embedded signatures unique to the disease. The concept is being extended to include cardio signals correlated with pulmonary data to provide an accurate and timely diagnoses of pulmonary function and distress in critically injured soldiers that will allow medical personnel to anticipate the need for accurate therapeutic intervention as well as monitor soldiers whose injuries may lead to pulmonary compromise later. The basic operation of the diagnostic system is as follows: (1) create an image from the acoustic signature based on higher order statistics, (2) deconstruct the image based on a predefined map, (3) compare the deconstructed image with stored images of pulmonary symptoms, and (4) classify the disorder based on a clustering of known symptoms and provide a statistical measure of confidence. The system has produced conformity between adults and infants and provided effective measures of physiology in the presence of noise.