Reflex syncope in the UK Armed Forces

Risk factors for reflex syncope in the British Army

INTRODUCTION

Reflex syncope in the UK Armed Forces is reportedly higher than comparable militaries and civilian populations and is significantly more common in soldiers who take part in State Ceremonial and Public Duties (SCPD) compared with other British Army service personnel (SP). This study aimed to investigate individual susceptibility factors for syncope in soldiers who regularly take part in SCPD.

METHODS

A retrospective cohort study was performed in 200 soldiers who perform SCPD. A questionnaire was undertaken reviewing soldiers' medical history and circumstances of any fainting episodes. A consented review of participants' electronic primary healthcare medical record was also performed. Participants were divided into two groups (syncope, n=80; control, n=120) based on whether they had previously fainted.

RESULTS

In the syncope group orthostasis (61%) and heat (35%) were the most common precipitating factors. The most common interventions used by soldiers were to maintain hydration (59%) and purposeful movements (predominantly 'toe wiggling'; 55%). 30% of participants who had previously fainted did not seek definitive medical attention. A history of migraines/headaches was found to increase the risk of reflex syncope (OR 8.880, 1.214-218.8), while a history of antihistamine prescription (OR 0.07144, 0.003671-0.4236), non-white ethnicity (OR 0.03401, 0.0007419-0.3972) and male sex (OR 0.2640, 0.08891-0.6915) were protective.

CONCLUSION

This is the first study, in the British Army, to describe, categorise and establish potential risk factors for reflex syncope. Orthostatic-mediated reflex syncope is the most common cause in soldiers who regularly perform SCPD and this is further exacerbated by heat exposure. Soldiers do not use evidence-based methods to avoid reflex syncope. These data could be used to target interventions for SP who have previously fainted or to prevent fainting during SCPD.

Nonfatal Injuries From Falls Among U.S. Military Personnel Deployed for Combat Operations, 2001-2018

INTRODUCTION

Falls are a leading mechanism of injury. Hospitalization and outpatient clinic visits due to fall injury are frequently reported among both deployed and non-deployed U.S. Military personnel. Falls have been previously identified as a leading injury second only to sports and exercise as a cause for non-battle air evacuations.

MATERIALS AND METHODS

This retrospective study analyzed the Department of Defense Trauma Registry fall injury data from September 11, 2001 to December 31, 2018. Deployed U.S. Military personnel with fall listed as one of their mechanisms of injury were included for analysis.

RESULTS

Of 31,791 injured U.S. Military personnel captured by the Department of Defense Trauma Registry within the study time frame, a total of 3,101 (9.8%) incurred injuries from falls. Those who had fall injuries were primarily 21 to 30 years old (55.4%), male (93.1%), Army (75.6%), and enlisted personnel (56.9%). The proportion of casualties sustaining injuries from falls generally increased through the years of the study. Most fall injuries were classified as non-battle injury (91.9%). Falls accounted for 24.2% of non-battle injury hospital admissions with a median hospital stay of 2 days. More non-battle-related falls were reported in Iraq-centric military operations (62.7%); whereas more battle-related falls were reported in Afghanistan-centric military operations (58.3%).

CONCLUSIONS

This study is the largest analysis of deployed U.S. Military personnel injured by falls to date. Highlighted are preventive strategies to mitigate fall injury, reduce workforce attrition, and preserve combat mission capability.

LEVEL OF EVIDENCE

Level III Epidemiologic.

The effect of water temperature on orthostatic tolerance: a randomised crossover trial

Purpose

Bolus water drinking, at room temperature, has been shown to improve orthostatic tolerance (OT), probably via sympathetic activation; however, it is not clear whether the temperature of the water bolus modifies the effect on OT or the cardiovascular responses to orthostatic stress. The aim of this study was to assess whether differing water temperature of the water bolus would alter time to presyncope and/or cardiovascular parameters during incremental orthostatic stress.

Methods

Fourteen participants underwent three head-up tilt (HUT) tests with graded lower body negative pressure (LBNP) continued until presyncope. Fifteen minutes prior to each HUT, participants drank a 500 mL bolus of water which was randomised, in single-blind crossover fashion, to either room temperature water (20 °C) (ROOM), ice-cold water (0–3 °C) (COLD) or warm water (45 °C) (WARM). Cardiovascular parameters were monitored continuously.

Results

There was no significant difference in OT in the COLD (33 ± 3 min; p = 0.3321) and WARM (32 ± 3 min; p = 0.6764) conditions in comparison to the ROOM condition (31 ± 3 min). During the HUT tests, heart rate and cardiac output were significantly reduced (p < 0.0073), with significantly increased systolic blood pressure, stroke volume, cerebral blood flow velocity and total peripheral resistance (p < 0.0054), in the COLD compared to ROOM conditions.

Conclusions

In healthy controls, bolus cold water drinking results in favourable orthostatic cardiovascular responses during HUT/LBNP without significantly altering OT. Using a cold water bolus may result in additional benefits in patients with orthostatic intolerance above those conferred by bolus water at room temperature (by ameliorating orthostatic tachycardia and enhancing vascular resistance responses). Further research in patients with orthostatic intolerance is warranted.