Remote physiological monitoring in an austere environment: a future for battlefield care provision?

Wearable technologies are making considerable advances into the mainstream as they become smaller and more user friendly. The global market for such devices is forecasted to be worth over US$5 billion in 2018, with one in six people owning a device. Many professional sporting teams use self-monitoring to assess physiological parameters and work rate on the pitch, highlighting the potential utility for military command chains. As size of device reduces and sensitivity improves, coupled with remote connectivity technology, integration into the military environment could be relatively seamless. Remote monitoring of personnel on the ground, giving live updates on their physiological status, would allow commanders or medical officers the ability to manage their soldiers appropriately and improve combat effectiveness. This paper explores a proof of concept for the use of a self-monitoring system in the austere high altitude environment of the Nepalese Himalayas, akin to those experienced by modern militaries fighting in remote locations. It also reviews, in part, the historical development of remote monitoring technologies. The system allowed for physiological recordings, plotted against GPS position, to be remotely monitored in Italy. Examples of the data recorded are given and the performance of the system is discussed, including limitations, potential areas of development and how systems like this one could be integrated into the military environment.

Incidence of acute mountain sickness in UK Military Personnel on Mount Kenya.

BACKGROUND: Acute mountain sickness (AMS) is a common problem of trekkers to high altitude. The UK military train at high altitude through adventurous training (AT) or as exercising troops. The ascent of Point Lenana at 4985 m on Mount Kenya is frequently attempted on AT. This study sought to establish the incidence of AMS within this population, to aid future planning for military activities at altitude. METHODS: A voluntary questionnaire was distributed to all British Army Training Unit Kenya based expeditions attempting to ascend Mount Kenya during the period from February to April 2014. The questionnaire included twice daily Lake Louise and Borg (perceived exertion scale) self-scoring. All expeditions were planned around a 5-day schedule, which included reserve time for acclimatisation, illness and inclement weather. RESULTS: Data were collected on 47 participants, 70% of whom reached the summit of Point Lenana. 62% (29/47) self-reported AMS (defined as Lake Louise score (LLS) ≥3) on at least one occasion during the ascent, and 34% (10/29) suffered severe AMS (LLS ≥6). Those who attempted the climb within 2 weeks of arrival in Kenya had a higher incidence of AMS (12/15 (80%) vs 17/32 (53%), p=0.077). Participants recording a high Borg score were significantly more likely to develop AMS (16/18 vs 9/21, p=0.003). CONCLUSIONS: This represents the first informative dataset for Mount Kenya ascents and altitude. The incidence of AMS during AT on Mount Kenya using this ascent profile is high. Adapting the current ascent profile, planning the ascent after time in country and reducing perceived exertion during the trek may reduce the incidence of AMS.

High altitude adaptation and illness: military implications.

British military personnel are frequently exposed to high altitude (HA) (>1500m). Operations in Afghanistan have occurred at altitudes of up to 3000m and there remains the possibility of rapid deployment of non-acclimatised troops to HA areas. British military personnel also deploy to HA frequently on Adventurous Training (AT) and there are numerous expeditions every year to the Greater Ranges. As such, there remains a reasonable likelihood of the development of high altitude illness (HAI) with potentially life-threatening consequences. This article aims to provide an overview of the adaptive (acclimatisation) and pathological (acute HAI) responses to HA exposure, with particular reference to military deployments.

Copeptin and arginine vasopressin at high altitude: relationship to plasma osmolality and perceived exertion.

PURPOSE: A diuresis is a key part of acclimatisation to high altitude (HA). Arginine vasopressin (AVP) is a hormone involved in salt and water balance and may potentially have a role in the development of altitude illness. ProAVP (copeptin) is more stable than AVP and is assayed by a straightforward, automated method. We investigated the relationship of AVP to copeptin and the copeptin response to exercise and altitude illness in a large cohort during a field study at HA. METHODS: 48 subjects took part in a 10-day trek at HA. Venous blood samples were taken at 3,833, 4,450 and 5,129 m post-trek (exercise) and the following day at rest. Daily recordings of symptoms of altitude illness, oxygen saturations and perceived exertion were carried out. RESULTS: AVP and copeptin levels increased with exercise and correlated closely (ρ 0.621 p < 0.001), this was strongest in the stressed state when AVP secretion was highest, at 5,129 m post-exercise (ρ 0.834 p < 0.001). On two-way ANOVA, both altitude (F = 3.5; p = 0.015) and exercise (F = 10.2; p = 0.002) influenced copeptin levels (interaction F = 2.2; p = 0.08). AVP levels were influenced by exercise (F = 14.4; p = 0.0002) but not altitude (F = 2.0; p = 0.12) with no overall group interactions (F = 1.92.6; p = 0.06). There was no association between copeptin or arginine vasopressin and altitude illness. Copeptin correlated with the Borg RPE score and was significantly higher in the group with a Borg score ≥15 (7.9 vs. 3.7 p < 0.001). CONCLUSION: We have shown that arginine vasopressin and copeptin levels correlate and are suppressed below 5,129 m. Furthermore, we have demonstrated that exertion, rather than altitude illness or increasing osmolality, is the stimulus for increases in copeptin.

A comparison of performance between Teflon and polyurethane safety cannulae at extremes of operating temperatures.

OBJECTIVES: In the United Kingdom, approximately eight million peripheral cannulations are performed each year. Intravenous cannulae are made from either polytetrafluoroethylene (Teflon) or polyurethane. Polyurethane has a lower incidence of thrombophlebitis, however the physical characteristics of polyurethane may make the cannulae difficult to use at higher ambient temperatures. This effect maybe of importance to those involved in cannulation in extreme environments and especially for military doctors deployed in current theatres of operations. METHODS: In a randomised single blinded study we investigated the different characteristics of Teflon and polyurethane cannulae (Vasofix Safety Cannulae, B Braun) at three different temperatures (-10 degrees C, 21 degrees C and 40 degrees C). RESULTS: There is no statistically significant difference in the ease or speed of cannulation of either polyurethane or Teflon safety cannulae in extremes of temperature. CONCLUSIONS: This study provides evidence that performance of polyurethane safety cannulae are not impaired by temperature extremes.

Anaesthetic and critical care management of thoracic injuries.

Thoracic wounding has been a relatively common presentation of military wounds throughout modern conflict. When civilian casualties are included the incidence has remained constant at around 10%, although the frequency and severity of wounds to combatants has been altered by modern body armour. Whilst thoracic injury has a high initial mortality on the battlefield, those surviving to reach hospital frequently have injuries that only require simple management. In addition to penetrating ballistic injury, blunt chest trauma frequently occurs on operations as a result of road traffic collisions or tertiary blast injury. The physiological impact of thoracic wounds, however, is often great and survivors often require intensive care management and, where available, complex strategies to ensure oxygenation and carbon dioxide removal. This review examines the incidence and patterns of thoracic trauma and looks at therapeutic options for managing these complex cases.

Resting and exercising cardiorespiratory variables and acute mountain sickness.

INTRODUCTION: The incidence of Acute Mountain Sickness (AMS) is increasing. In a military context our current operational areas include mountainous regions with the implications of AMS including loss of operational tempo and logistical overstretch. Oxygen saturation and heart rate variability have in some studies been predictive of AMS while in others not. No single factor has been demonstrated consistently to be predictive of developing AMS. METHODS: During an expedition to climb Mt Aconcagua (6959m) we explored the relationship between cardiorespiratory variables and AMS. In 11 subjects we measured simple physiological variables and Lake Louise Score both pre and post a standardised exercise challenge at on arrival at different altitudes and after a period of acclimatization. RESULTS: The changes in cardiorespiratory variables we observed with altitude were consistent with previous studies. Heart rate, respiratory rate and blood pressure increased whilst oxygen saturation reduced. Over time at altitude, respiratory rate and heart rate were maintained whilst there was a reduction in blood pressure towards sea level values. Oxygen saturations improved over time at altitude and the change in heart rate on exercise was reduced with acclimatization. In this small pilot study individuals with AMS may have a greater heart rate response to exercise than non-AMS subjects and this may warrant further investigation. CONCLUSIONS: The incidence of AMS in our study was low reflecting a conservative ascent profile. Further larger studies are necessary to fully assess the predictive value of cardiorespiratory variables in AMS.

Anaesthesia in austere environments.

The scope of this review is by necessity somewhat limited and, as said in the introduction, methods used will depend on the skills and experience of the practitioner involved. The triservice apparatus remains the system of choice for delivering volatile anaesthetic agents to patients in areas without the infrastructure to supply an endless quantity of medical gases, the planned isolated or battle conditions of Boultons scenarios. The TSA's portability, robust design and versatility have stood the test of time. By reviewing intravenous agents the author has attempted to find an evidence base for the most appropriate agent for a non anaesthetic trained doctor finding his or herself called on to provide emergency anaesthesia in the field. The most useful drug is ketamine which has the advantage of cardiovascular stability, preservation of airway reflexes, ease of administration via different routes and versatility for providing analgesia, sedation or general anaesthesia.

Vasodilator pre-treatment of human radial arteries; comparison of effects of phenoxybenzamine vs papaverine on norepinephrine-induced contraction in vitro.

AIMS: The radial artery, increasingly used for coronary artery bypass grafting (CABG). has a potential for spasm which may increase peri-operative risk. Increased alpha-adrenoceptor activation is a key candidate for the spasm. We studied the effects of vasoconstriction in a radial artery, which had undergone brief exposure to the alpha-adrenoceptor antagonist phenoxybenzamine vs the opioid derivative papaverine. METHODS AND RESULTS: Using standard classical organ bath techniques, concentration responses were obtained to norepinephrine in segments of radial artery from 12 CABG patients pre- and post-incubation for 20 min in either phenoxybenzamine 10(-6) M or papaverine 3 x 10(-3) M. Responses were reassessed 2, 4 and 18 h after washout of phenoxybenzamine and 2, 4, 8 and 18 h after washout of papaverine. There was concentration-dependent constriction to norepinephrine (maximum response 0.89 +/- 0.20 (SEM) g x mm(-1), n=6). Constriction to norepinephrine was abolished immediately after incubation in phenoxybenzamine and remained completely inhibited for at least 18 h (P<0.0001 ANOVA phenoxybenzamine pre-treated vs controls). Most of the inhibition of concentration-dependent constriction to norepinephrine following pre-treatment with papaverine was lost 8 h later. CONCLUSION: Radial artery vasoconstriction induced by a clinically relevant agonist, norepinephrine, may be prevented for at least 18 h by pre-incubation in phenoxybenzamine, in contrast to the brief inhibition achieved by pre-treatment with papaverine. Adding phenoxybenzamine to radial artery graft bathing solution may improve early outcome following CABG.

Helicopter medical retrieval in Sydney, New South Wales.

Undoubtedly the main attraction of this job is the interest of never knowing what will happen next! Primary response to an MVA allows one to experience the atmosphere and deal with clinical situations in an alien setting. This broadens ones perspective and has taught me never to be tempted to criticise a paramedic bringing a patient into a resus room. The same is true of interhospital transfers where tact and diplomacy can be tested as well as clinical skills. On the negative side the unpredictability can be difficult domestically (a primary at 17555 means you will be at least two hours late home) and there can be long and dull days when nothing happens. A lot of time is spent transporting post arrest patients from one hospital to another to find an ICU bed. In military medicine it is difficult to envisage a future conflict when severely injured casualties would not require transport both locally and over long distances. This job provides an ideal opportunity to become confident with transporting critically ill patients.