Hypocalcemia in Military Casualties From Point of Injury to Surgical Teams in Afghanistan.

INTRODUCTION: Hypocalcemia is a known sequela of citrated blood product transfusion. Civilian data suggest hypocalcemia on hospital admission is associated with worse outcomes. Initial calcium levels in military casualties have not previously been analyzed. The objective of this retrospective review aimed to assess the initial calcium levels in military trauma casualties at different Forward Surgical Teams (FST) locations in Afghanistan and describe the effects of prehospital blood product administration on arrival calcium levels. MATERIALS AND METHODS: This is a retrospective cohort analysis of military casualties arriving from point of injury to one of two FSTs in Afghanistan from August 2018 to February 2019 split into four locations. The primary outcome was incidence of hypocalcemia (ionized calcium < 1.20 mmol/L). RESULTS: There were 101 patients included; 55 (54.5%) experienced hypocalcemia on arrival to the FST with a mean calcium of 1.16 mmol/L (95% confidence interval [CI], 1.14 to 1.18). The predominant mechanism of injury consisted of blast patterns, 46 (45.5%), which conferred an increased risk of hypocalcemia compared to all other patterns of injury (odds ratio = 2.42, P = .042). Thirty-eight (37.6%) patients required blood product transfusion. Thirty-three (86.8%) of the patients requiring blood product transfusion were hypocalcemic on arrival. Mean initial calcium of patients receiving blood product was 1.13 mmol/L (95% CI, 1.08 to 1.18), which was significantly lower than those who did not require transfusion (P = .01). Eight (7.9%) of the patients received blood products before arrival, with 6/8 (75%) presenting with hypocalcemia. CONCLUSIONS: Hypocalcemia develops rapidly in military casualties and is prevalent on admission even before transfusion of citrated blood products. Blast injuries may confer an increased risk of developing hypocalcemia. This data support earlier use of calcium supplementation during resuscitation.

Thermal Burn Injury from a Wedding Ring: An Unusual Case.

Thermal ring injuries are rarely reported in the literature. For this reason, treatment is varied without a standard approach. We describe a case of a thermal wedding ring injury sustained during a welding accident. It is critical to understand the 3 zones of burn injuries when managing these infrequent cases. Furthermore, the dynamic progression that ensues a thermal burn will directly affect outcome. A case is presented along with a graduated approach to the management of such injuries.

Design Rationale and Preclinical Evaluation of the HeartMate 3 Left Ventricular Assist System for Hemocompatibility.

The HeartMate 3 (HM3) left ventricular assist device (LVAD) is designed to support advanced heart failure patients. This centrifugal flow pump has a magnetically levitated rotor, artificial pulse, textured blood-contacting surfaces, optimized fluid dynamics, large blood-flow gaps, and low shear stress. Preclinical tests were conducted to assess hemocompatibility. A computational fluid dynamics (CFD) model guided design for low shear stress and sufficient washing. Hemolysis testing was conducted on six pumps. Plasma-free hemoglobin (PfHb) and modified index of hemolysis (MIH) were compared with HeartMate II (HMII). CFD showed secondary flow path residence times between 27 and 798 min, comparable with main flow residence times between 118 and 587 min; HM3 vs. HMII shear stress exposure above 150 Pa was 3.3 vs. 11 mm within the pump volume and 134 vs. 604 mm on surfaces. In in vitro hemolysis tests at 2, 5, and 10 L/min, average pfHb 6 hours after test initiation was 58, 74, and 157 mg/dl, compared with 112, 123, and 353 mg/dl for HMII. The HM3/HMII ratio of average MIH at 2, 5, and 10 L/min was 0.29, 0.36, and 0.22. Eight 60 day bovine implants were tested with average flow rates from 5.6 to 6.4 L/min with no device failures, thrombosis, or hemolysis. Results support advancing HM3 to clinical trials.

Towards a brain controlled assistive technology for powered mobility.

For individuals with mobility limitations, powered wheelchair systems provide improved functionality, increased access to healthcare, education and social activities. Input devices such as joystick and switches can provide the necessary input required for efficient control of the powered wheelchair. For persons with limited dexterity, or fine control of the fingers, access to mechanical hardware such as buttons and joysticks can be quite difficult and sometimes painful. For individuals with conditions such as Traumatic Brain Injury (TBI), Multiple Sclerosis (MS) or Amyotrophic lateral sclerosis (ALS) voluntary control of limb movement maybe substantially limited or completely absent. Brain Computer Interfaces (BCI) are emerging as a possible method to replace the brains normal output pathways of peripheral nerves and muscles, allowing individuals with paralysis a method of communication and computer control. This study involves the analysis of non-invasive electroencephalograms (EEG) arising from the use of a newly developed Human Machine Interface (HMI) for powered wheelchair control. Using a delayed response task, binary classification of left and right movement intentions were classified with a best classification rate of 81.63% from single trial EEG. Results suggest that this method may be used to enhance control of HMI's for individuals with severe mobility limitations.

Accelerometer based measurement for the mapping of neck surface vibrations during vocalized speech.

This paper presents a detailed study of the vibrations on the surface of the neck during a vocalization of predefined fundamental frequency and intensity. This study was carried out as part of a wider investigation into the use of laryngeal vibrations as a channel of communication. Another potential application of this study is in identifying a suitable location for a hands-free electro-larynx for laryngectomees. An analog accelerometer, with dimensions 5x5x1.6mm and of mass 80mg, was used to perform the measurements. It was connected to a 12-bit analog to digital converter via single strands of insulated wire with a diameter of 100 microm. The resulting low inertia of the measuring device minimised the effect of the measuring device on the phenomenon under investigation. The analog to digital converter simultaneously sampled the accelerometer output and a pre-amplified audio signal from a microphone. This preliminary study was carried out on two able-bodied male subjects. Measurements were taken from forty-five preselected locations on the neck. Each subject made the vowel sound /i/ (long 'e') at three different fundamental frequencies, 150Hz, 200Hz and 250Hz. Once the vocal pitch and intensity matched pre-defined target values, a 200 ms recording was captured by a virtual instrument designed in LabVIEW. A detailed map of skin surface vibration amplitude during vocalization is presented and suitable locations for laryngeal vibration measurement are identified. Further more, detailed analysis of the time varying acceleration function at various measurement positions reveals a rich and complex source of information. Novel visualizations of these signals are presented.

An electrooculogram-based binary saccade sequence classification (BSSC) technique for augmentative communication and control.

In the field of assistive technology, the electrooculogram (EOG) can be used as a channel of communication and the basis of a man-machine interface. For many people with severe motor disabilities, simple actions such as changing the TV channel require assistance. This paper describes a method of detecting saccadic eye movements and the use of a saccade sequence classification algorithm to facilitate communication and control. Saccades are fast eye movements that occurs when a person's gaze jumps from one fixation point to another. The classification is based on pre-defined sequences of saccades, guided by a static visual template (e.g. a page or poster). The template, consisting of a table of symbols each having a clearly identifiable fixation point, is situated within view of the user. To execute a particular command, the user moves his or her gaze through a pre-defined path of eye movements. This results in a well-formed sequence of saccades which are translated into a command if a match is found in a library of predefined sequences. A coordinate transformation algorithm is applied to each candidate sequence of recorded saccades to mitigate the effect of changes in the user's position and orientation relative to the visual template. Upon recognition of a saccade sequence from the library, its associated command is executed. A preliminary experiment in which two subjects were instructed to perform a series of command sequences consisting of 8 different commands are presented in the final sections. The system is also shown to be extensible to facilitate convenient text entry via an alphabetic visual template.

Community-oriented medical emergency programme: development and evaluation issues.

A community-oriented medical emergency programme for multidisciplinary healthcare professionals on the Higher Professional Diploma in International Healthcare Studies, at the United Medical Education College, London is described. The main aim of the course is to introduce students to the clinical skills of dealing with medical emergency problems and situations. Students are also exposed to how medical emergency is practised in the community. The four-week programme consists of 16 sessions of clinical skills teaching where students are attached to various community clinics, 10 sessions of college teaching, consisting of talks, workshops and interactive small-group work and four sessions encouraging students to learn independently in a self-directed learning format. Student and tutor evaluations of the programme demonstrate that its aims are being met. However, further adaptation of the module to increase the range and quantity of clinical cases for student learning is being planned.