Pre-screening and preventive quarantine likely explains the low SARS-CoV-2 prevalence among Norwegian conscripts.

Objective: We aim to discuss whether preventive quarantine can mitigate the spread of Covid-19 during the pandemic. Design: We did a cross-sectional, observational study design in a mass-screening program in the enrolment to the Norwegian military during April 19-28th 2020 (COVID-NOR-MIL). Subjects: 1170 presumptively healthy young Norwegian conscripts. Setting: A structured interview encouraged the coming conscripts to a self-imposed preventive quarantine the last two weeks before enrolment. Main outcome measures: All conscripts underwent a PCR-based test with nasopharyngeal swabs at the day of enrolment. Results: Only two tested positive. The study discusses the predictive value of the RT-PCR test and the risk of false positive and false negative results, particularly when using the test in a low-prevalent cohort, even if the test properties of sensitivity and specificity is almost 100%. Further, the study discusses the challenge of whether a positive SARS-CoV-2 PCR-test represent viable and contagious virus or only viral remnants. Conclusion: The adherence to self-imposed preventive quarantine is a challenge and is a subject to further research. Implications: We want to draw the attention to the potential value of a thorough pre-screening processes and self-imposed preventive quarantine to minimize the potential spread of SARS-Cov-2.

Cardiac stroke volume variability measured non-invasively by three methods for detection of central hypovolemia in healthy humans.

PURPOSE: Hypovolemia decreases preload and cardiac stroke volume. Cardiac stroke volume (SV) and its variability (cardiac stroke volume variability, SVV) have been proposed as clinical tools for detection of acute hemorrhage. We compared three non-invasive SV measurements and investigated if respiration-induced fluctuations in SV may detect mild and moderate hypovolemia in spontaneously breathing humans. METHODS: Ten healthy subjects underwent experimental central hypovolemia induced by lower body negative pressure to -60 mmHg or onset of presyncopal symptoms. SV beat-to-beat was estimated simultaneously by ultrasound Doppler, finger arterial blood pressure curve and impedance cardiography. SVV was calculated by spectral analysis between 0.15 and 0.40 Hz. RESULTS: Relative changes in SV did not show significant differences between the methods. The SVV measured by ultrasound Doppler and arterial blood pressure curve decreased at -30 mmHg to 32 % (ultrasound Doppler: 95 % CI 18-47, arterial blood pressure curve: 95 % CI 21-43) and at maximal simulated hypovolemia to 23 % (ultrasound Doppler: 95 % CI 14-81) and 21 % (arterial blood pressure curve: 95 % CI 9-33) of baseline variability. The variability in cardiac stroke volume from the impedance cardiography did not change significantly during the simulated hypovolemia, to 88 and 76 % of baseline variability. CONCLUSION: Cardiac stroke volume estimated by ultrasound Doppler and by arterial blood pressure curve showed parallel variations beat-to-beat during simulated hemorrhage, whereas impedance cardiography did not appear to track beat-to-beat changes in cardiac stroke volume. The variability in cardiac stroke volume was decreased during mild and moderate hypovolemia and could be used for early detection of hypovolemia.

Nine treatments of 1000 mL therapeutic phlebotomy in a subject with polycythemia: A case report.

Large-volume therapeutic phlebotomy is the mainstay of hemochromatosis treatment and offers an opportunity to investigate the hemodynamic changes during acute hypovolemia. An otherwise healthy 64-year-old male with hemochromatosis participated. On nine separate visits, 1000 mL therapeutic phlebotomy was performed. On one occasion, pre- and post-phlebotomy orthostatic challenge with 27° reverse Trendelenburg position was administered. Mean arterial pressure, heart rate, and stroke volume were measured continuously during the procedures. The patient's tolerance to the interventions was continuously evaluated. The procedures were well tolerated by the patient. Mean arterial pressure was maintained during hemorrhage and following phlebotomy in both supine and reverse Trendelenburg positions, primarily through an increase in heart rate and systemic vascular resistance. The present study found that 1000 mL therapeutic phlebotomy in a patient with hemochromatosis may be acceptably and safely used to model hemorrhage. The approach demonstrates high clinical applicability and ethically robustness in comparison with volunteer studies.

Donor performance of combat readiness skills of special forces soldiers are maintained immediately after whole blood donation: a study to support the development of a prehospital fresh whole blood transfusion program.

BACKGROUND: Bleeding is a major cause of death in combat settings, and combat casualties in shock may benefit from fresh whole blood (FWB) transfusion. "Buddy transfusion" is a well-known lifesaving intervention, but little is known about donor combat safety aspects immediately after blood donation. The objectives of this study were to explore the effects of donation of 1 unit of blood on physical and combat-related performance among active duty soldiers. We also investigated the feasibility of a short training program to teach nonmedics buddy transfusion. STUDY DESIGN AND METHODS: Twenty-five fit male soldiers from a special forces unit were divided into three groups and tested on 1) a Bruce protocol treadmill stress test, push-ups, and pull-ups; 2) a 50-round rapid pistol shooting test; and 3) an uphill hiking exercise carrying a 20-kg backpack. After baseline testing, the soldiers performed the tests again (2-6 min) after donating 450 mL of blood. The training program included blood collection and reinfusion procedures and we measured success rate of venipuncture, time for blood collection, and success in placing sternal intraosseous needle and reinfusing 1 unit of autologous blood. RESULTS: We did not find any significant decrease in performance either in physical or in shooting performance after donating blood. Nonmedic soldiers had a 100% success rate in blood collection and also infusion on fellow soldiers after a short introduction to the procedures. CONCLUSION: This study supports the fact that buddy transfusion may be feasible for healthy well-trained soldiers and does not decrease donor combat performance under ideal circumstances.

Symposium on fresh whole blood for severe hemorrhagic shock: from in-hospital to far forward resuscitations.

This report is prepared for The Hemostasis and Oxygenation Research (THOR) Network and based on presentations of invited THOR investigators. In order to make it available to a larger group of interested readers it has been agreed to publish the report in TRASCI, as a "what is happening?" in view of its importance and novelty. On June 14th 2011 the first symposium on fresh whole blood (FWB) was held in Bergen, Norway. THOR network leadership, which includes Tor Hervig, PhD, MD, Geir Strandenes, MD, Erling Bekkestad Rein, MD, and Philip C. Spinella, MD, organized the event. It was sponsored by the Royal Norwegian Navy Medical Service, Norwegian Armed Forces Medical Services and Caridian BCT. The objective of this meeting was to bring together investigators from around the world who are interested in analyzing the efficacy and safety of FWB for patients with severe traumatic hemorrhagic shock and to determine the initial steps in developing a research program in this area. The THOR network is specifically interested in determining if FWB can improve morbidity and mortality in combat casualties with life threatening hemorrhagic shock. A three-year research proposal has been developed by the THOR network to determine (1) if FWB donation adversely affects donor performance of combat related skills, (2) the optimal storage solution, temperature, and acceptable storage duration for FWB, (3) the logistics of providing FWB in a combat environment safely to include optimal transport and administration methods. The symposium speakers were tasked with reviewing current data on; coagulopathy associated with massive traumatic bleeding, immunology of transfusion, outcomes associated with FWB use, logistic and medical issues of the use of FWB in far forward situations, training required for medics on FWB collection and administration, the risks of FWB and stored blood components and methods to mitigate these risks. The meeting concluded with a discussion of the THOR network's three-year research program.

Abstracts from The Cold Weather Operations Conference 2021.

A common effort for both military and civil healthcare is to achieve knowledge-based health care in cold weather injuries and fatal accidents in harsh arctic environment. The Cold Weather Operations Conference in November 2021, having more than 300 participants from 20 countries, was addressing the prevention and treatment of injuries and trauma care in cold weather conditions and the challenges for military prehospital casualty care. The intention of the programme was to stimulate further research and systematic knowledge-based clinical work. The abstracts from the conference present cold weather research and clinical experience relevant for readers of the International Journal of Circumpolar Health.

Body temperature control in rats by muscle tone during rest or sleep.

AIM: To explore the role of tonic motor unit activity in body temperature control. METHODS: Motor unit activity in soleus and several other skeletal muscles was recorded electromyographically from adult rats placed in a climate chamber on a load sensitive floor, which, together with video monitoring, allowed detection of every successive period of movement and no movement. RESULTS: In the absence of movements during rest or sleep, motor unit activity was exclusively tonic and therefore equivalent to muscle tone as defined here. The amount of tonic activity increased linearly in the soleus as the ambient temperature decreased from 32°C to below 7°C, owing to progressive recruitment and increased firing rate of individual units. Brief movements occurred randomly and frequently during rest or sleep in association with brief facilitation or inhibition of motor neurons that turned tonic motor unit activity on or off, partitioning the tonic activity among the available motor units. Shivering first appeared when a falling ambient temperature reached ≤7°C in several muscles except soleus, which was as active between shivering bursts as during them. CONCLUSION: Muscle tone and overt shivering are strikingly different phenomena. Tonic motor unit activity in the absence of movements evokes isometric contractions and, therefore, generates heat. Accordingly, when the amount of tonic activity increases with falling ambient temperature, so must heat production. Consequently, graded muscle tone appears as an important and independent mechanism for thermogenesis during rest or sleep at ambient temperatures ranging from <7°C to at least 32°C.

Junctional Tourniquet Training Experience.

Since 2009, out-of-hospital care of junctional hemorrhage bleeding from the trunk-appendage junctions has changed, in part, due to the newly available junctional tourniquets (JTs) that have been cleared by the US Food and Drug Administration. Given four new models of JT available in 2014, several military services have begun to acquire, train, or even use such JTs in care. The ability of users to be trained in JT use has been observed by multiple instructors. The experience of such instructors has been broad as a group, but their experience as individuals has been neither long nor deep. A gathering into one source of the collective experience of trainers of JT users could permit a collation of useful information to include lessons learned, tips in skill performance, identification of pitfalls of use to avoid, and strategies to optimize user learning. The purpose of the present review is to record the experiences of several medical personnel in their JT training of users to provide a guide for future trainers.

Preventing hyperthermia: a cross-over study comparing two negative pressure devices during continuous passive heat stress.

Heat-related illness and mortality increase significantly during heatwaves. Out-of-hospital treatment to avoid elevation of body core temperature (hyperthermia) could be beneficial for selected patients. Negative pressure devices have been proposed as an effective treatment method. This study compared the effects of two devices on healthy volunteers under continuous passive heat stress in a climatic chamber. Nine subjects were studied in a prospective cross-over study on two separate days. Subjects were randomized to treatment with either CoreControl® (CC) or ThermoTube (TT) on the first day. They were exposed to an ambient temperature above skin temperature and high air humidity throughout the experiment. Treatment intended to prevent the development of hyperthermia started after 60 min of passive warming. Core temperature continued to rise during treatment with CC, whereas it dropped slightly and then stabilized during treatment with TT.