Aluminium release and fluid warming: provocational setting and devices at risk.

BACKGROUND: Fluid warming, recommended for fluid rates of > 500 ml h-1, is an integral part of patient temperature management strategies. Fluid warming devices using an uncoated aluminium containing heating element have been reported to liberate aluminium resulting in critical aluminium concentrations in heated fluids. We investigated saline solution (0.9%), artificially spiked with organic acids to determine the influence of fluid composition on aluminium release using the uncoated enFlow® device. Additionally, the Level1® as a high volume fluid warming device and the ThermoSens® device were investigated with artificial spiked fluid at high risk for aluminum release and a clinically used crystalloid solution. RESULTS: Saline solution spiked with lactate more than acetate, especially at a non neutral pH, led to high aluminium release. Next to the enFlow® device, aluminium release was observed for the Level1® device, but not for the coated ThermoSens®-device. CONCLUSION: Uncoated aluminium containing fluid warming devices lead to potentially toxic levels of aluminium in heated fluids, especially in fluids with non-neutral pH containing organic acids and their salts like balanced electrolyte solutions.

Vacuum mattress or long spine board: which method of spinal stabilisation in trauma patients is more time consuming? A simulation study.

BACKGROUND: Spinal stabilisation is recommended for prehospital trauma treatment. In Germany, vacuum mattresses are traditionally used for spinal stabilisation, whereas in anglo-american countries, long spine boards are preferred. While it is recommended that the on-scene time is as short as possible, even less than 10 minutes for unstable patients, spinal stabilisation is a time-consuming procedure. For this reason, the time needed for spinal stabilisation may prevent the on-scene time from being brief. The aim of this simulation study was to compare the time required for spinal stabilisation between a scoop stretcher in conjunction with a vacuum mattress and a long spine board. METHODS: Medical personnel of different professions were asked to perform spinal immobilizations with both methods. A total of 172 volunteers were immobilized under ideal conditions as well as under realistic conditions. A vacuum mattress was used for 78 spinal stabilisations, and a long spinal board was used for 94. The duration of the procedures were measured by video analysis. RESULTS: Under ideal conditions, spinal stabilisation on a vacuum mattress and a spine board required 254.4 s (95 % CI 235.6-273.2 s) and 83.4 s (95 % CI 77.5-89.3 s), respectively (p < 0.01). Under realistic conditions, the vacuum mattress and spine board required 358.3 s (95 % CI 316.0-400.6 s) and 112.6 s (95 % CI 102.6-122.6 s), respectively (p < 0.01). CONCLUSIONS: Spinal stabilisation for trauma patients is significantly more time consuming on a vacuum mattress than on a long spine board. Considering that the prehospital time of EMS should not exceed 60 minutes and the on-scene time should not exceed 30 minutes or even 10 minutes if the patient is in extremis, based on our results, spinal stabilisation on a vacuum mattress may consume more than 20 % of the recommended on-scene time. In contrast, stabilisation on a spine board requires only one third of the time required for that on a vacuum mattress. We conclude that a long spine board may be feasible for spinal stabilisation for critical trauma patients with timesensitive life threatening ABCDE-problems to ensure the shortest possible on-scene time for prehospital trauma treatment, not least if a patient has to be rescued from an open or inaccessible terrain, especially that with uneven overgrown land.

Aluminium release by coated and uncoated fluid-warming devices.

The use of fluid-warming systems is recommended for infusion rates > 500 ml.h-1 to avoid peri-operative hypothermia. Some fluid-warming devices use disposable aluminium-heated plates for heat transfer, but there is no protective coating to separate the fluid from the heated aluminium surface. It is unknown if this could promote release of aluminium into infusion fluids. We investigated a coated (Fluido compact) and an uncoated (enFlow) fluid-warming device using normal saline or balanced electrolyte solution as infusion fluids, pumped through the heated disposables at flow rates of 2, 4 and 8 ml.min-1 for 60 min each. Aluminium concentrations in the fluid samples were analysed using graphite furnace atomic absorption spectrometry. With saline the coated and uncoated devices yielded aluminium concentrations below the level of quantification (< 128 µg.l-1 ). Similarly, balanced electrolyte solution in the coated device yielded aluminium concentrations < 128 µg.l-1 . However, balanced electrolyte solution in the uncoated device yielded aluminium concentrations of up to 6794 (3465-8002 [1868-7421]) µg.l-1 . Repeating this last study at a flow rate of 2 ml.min-1 resulted in quite high aluminium concentrations when the uncoated device was not heated (~1000 µg.l-1 ) and higher concentrations after the device was heated. We conclude that using uncoated aluminium plates in fluid-warming systems can lead to a risk of administering potentially harmful concentrations of aluminium when balanced crystalloid solutions are used. The mechanism is unclear, but heat is in part involved. Coating for aluminium within medical devices in direct contact with infusion fluids should be recommended.

A spiky pattern in the course of electrical thoracic impedance as a very early sign of a developing pneumothorax.

A pneumothorax (PTX) is a potentially lethal condition in high-risk intensive care patients. Electrical impedance tomography (EIT) has been proven to detect PTX at the bedside. A so far not described pattern in the course of thoracic impedance at an early state of PTX was observed in a pig model of ventilator-induced lung injury (VILI) used for a more extensive study. EIT was performed at a framerate of 50 Hz. Beginning of PTX at normal ventilation, manifestation of PTX at VILI ventilation (plateau pressure 42 cm H2 O) and final pleural drainage were documented. At ventilation with 8·6 ml kg-1 , early PTX findings prior to any clinical deterioration consisted in a spike-like pattern in the time course of impedance (relative impedance change referred to initial end-expiratory level). Spike amplitudes (mean ± SD) were the following: 0·154 ± 0·059 (right lung) and 0·048 ± 0·050 (left lung). At this state, end-expiratory levels (mean ± SD) were still similar, -0·035 ± 0·010 (right) and -0·058 ± 0·022 (left). After application of VILI ventilation (38 ml kg-1 ), a PTX developed slowly, being confirmed by a continuous increase in the end-expiratory level on the right side and diverging levels of +0·320 ± 0·057 (right) and -0·193 ± 0·147 (left) at full manifestation. We assume that spikes reflect a temporary change in the electrical pathway caused by leakage into the pleural cavity. This newly described phenomenon of spikes is considered to be a potentially useful indicator for a very early detection of an evolving PTX in high-risk ICU patients.