Evaluating cold, wind, and moisture protection of different coverings for prehospital maritime transportation-a thermal manikin and human study

Rescue Blankets as Multifunctional Rescue Equipment in Alpine and Wilderness Emergencies-A Narrative Review and Clinical Implications

The utilization of rescue blankets in pre-hospital emergency medicine exceeds protection from hypothermia and enhanced visibility by far. In this narrative review, we focus on emphasizing the alternative applications of these fascinating multifunctional tools in the pre-hospital setting. A literature search in PubMed^® and Web of Science^TM yielded 100 results (last update was on 8 July 2022), a total number of 26 of which were included in this narrative review. Nine articles assessing alternative functions of rescue blanket were further evaluated and described in more detail. In addition, we performed various experimental and observational trials to test the functionality of rescue practice in mountain emergency medicine. Newly fabricated rescue blankets proved to possess impressive robustness. We evaluated rescue blankets in their applicability to not only protect from hypothermia, but also as practical tools to treat catastrophic hemorrhage and bleeding limbs, to perform open pneumothorax chest seals in sucking chest wounds, to prevent damage to unprotected eyes on the glacier and as alternative instruments for transportation in the inaccessible areas. Rescue blankets are important rescue equipment in alpine and wilderness emergencies with multifunctional applications, and must be part of every personal medical kit.

Prehospital Use of Ultrathin Reflective Foils

Ultrathin reflective foils (URFs) are widely used to protect patients from heat loss, but there is no clear evidence that they are effective. We review the physics of thermal insulation by URFs and discuss their clinical applications. A conventional view is that the high reflectivity of the metallic side of the URF is responsible for thermal protection. In most circumstances, the heat radiated from a well-clothed body is minimal and the reflecting properties of a URF are relatively insignificant. The reflection of radiant heat can be impaired by condensation and freezing of the moisture on the inner surface and by a tight fit of the URF against the outermost layer of insulation. The protection by thermal insulating materials depends mostly on the ability to trap air and increases with the number of covering layers. A URF as a single layer may be useful in low wind conditions and moderate ambient temperature, but in cold and windy conditions a URF probably best serves as a waterproof outer covering. When a URF is used to protect against hypothermia in a wilderness emergency, it does not matter whether the gold or silver side is facing outward.

Managing accidental hypothermia: a UK-wide survey of prehospital and search and rescue providers

AIM

The management of hypothermic casualties is a challenge faced by all prehospital and search and rescue (SAR) teams. It is not known how the practice of these diverse teams compare. The aim of this study was to review prehospital hypothermia management across a wide range of SAR providers in the UK.

METHODS

A survey of ground ambulances (GAs), air ambulances (AAs), mountain rescue teams (MRTs, including Ministry of Defence), lowland rescue teams (LRTs), cave rescue teams (CRTs), and lifeboats and lifeguard organisations (LLOs) across the UK was conducted between May and November 2017. In total, 189 teams were contacted. Questions investigated packaging methods, temperature measurement and protocols for managing hypothermic casualties.

RESULTS

Response rate was 59%, comprising 112 teams from a wide range of organisations. Heavyweight (>3 kg) casualty bags were used by all CRTs, 81% of MRTs, 29% of LRTs, 18% of AAs and 8% of LLOs. Specially designed lightweight (<0.5 kg) blankets or wraps were used by 93% of LRTs, 85% of LLOs, 82% of GAs, 71% of AAs and 50% of MRTs. Bubble wrap was used mainly by AAs, with 35% of AAs reporting its use. Overall, 94% of packaging methods incorporated both insulating and vapour-tight layers. Active warming by heated pads or blankets was used by 65% of AAs, 60% of CRTs, 54% of MRTs, 29% of LRTs and 9% of GAs, with no LLO use. Temperature measurement was reported by all AAs and GAs, 93% of LRTs, 80% of CRTs, 75% of MRTs and 31% of LLOs. The favoured anatomical site for temperature measurement was tympanic. Protocols for packaging hypothermic casualties were reported by 73% of services.

CONCLUSIONS

This survey describes current practice in prehospital hypothermia management, comparing the various methods used by different teams, and provides a basis to direct further education and research.

Thermal comfort sustained by cold protective clothing in Arctic open-pit mining-a thermal manikin and questionnaire study

Workers in the Arctic open-pit mines are exposed to harsh weather conditions. Employers are required to provide protective clothing for workers. This can be the outer layer, but sometimes also inner or middle layers are provided. This study aimed to determine how Arctic open-pit miners protect themselves against cold and the sufficiency, and the selection criteria of the garments. Workers' cold experiences and the clothing in four Arctic open-pit mines in Finland, Sweden, Norway and Russia were evaluated by a questionnaire (n=1,323). Basic thermal insulation (I_cl) of the reported clothing was estimated (ISO 9920). The I_cl of clothing from the mines were also measured by thermal manikin (standing/walking) in 0.3 and 4.0 m/s wind. The questionnaire showed that the I_cl of the selected clothing was on average 1.2 and 1.5 clo in mild (-5 to +5°C) and dry cold (-20 to -10°C) conditions, respectively. The I_cl of the clothing measured by thermal manikin was 1.9-2.3 clo. The results show that the Arctic open-pit miners' selected their clothing based on occupational (time outdoors), environmental (temperature, wind, moisture) and individual factors (cold sensitivity, general health). However, the selected clothing was not sufficient to prevent cooling completely at ambient temperatures below -10°C.

Accidental hypothermia-an update : The content of this review is endorsed by the International Commission for Mountain Emergency Medicine (ICAR MEDCOM)

BACKGROUND

This paper provides an up-to-date review of the management and outcome of accidental hypothermia patients with and without cardiac arrest.

METHODS

The authors reviewed the relevant literature in their specialist field. Summaries were merged, discussed and approved to produce this narrative review.

RESULTS

The hospital use of minimally-invasive rewarming for non-arrested, otherwise healthy, patients with primary hypothermia and stable vital signs has the potential to substantially decrease morbidity and mortality for these patients. Extracorporeal life support (ECLS) has revolutionised the management of hypothermic cardiac arrest, with survival rates approaching 100 % in some cases. Hypothermic patients with risk factors for imminent cardiac arrest (temperature <28 °C, ventricular arrhythmia, systolic blood pressure <90 mmHg), and those who have already arrested, should be transferred directly to an ECLS-centre. Cardiac arrest patients should receive continuous cardiopulmonary resuscitation (CPR) during transfer. If prolonged transport is required or terrain is difficult, mechanical CPR can be helpful. Delayed or intermittent CPR may be appropriate in hypothermic arrest when continuous CPR is impossible. Modern post-resuscitation care should be implemented following hypothermic arrest. Structured protocols should be in place to optimise pre-hospital triage, transport and treatment as well as in-hospital management, including detailed criteria and protocols for the use of ECLS and post-resuscitation care.

CONCLUSIONS

Based on new evidence, additional clinical experience and clearer management guidelines and documentation, the treatment of accidental hypothermia has been refined. ECLS has substantially improved survival and is the treatment of choice in the patient with unstable circulation or cardiac arrest.

Evaluating cold, wind, and moisture protection of different coverings for prehospital maritime transportation-a thermal manikin and human study

INTRODUCTION

Prehospital maritime transportation in northern areas sets high demands on hypothermia prevention. To prevent body cooling and hypothermia of seriously-ill or injured casualties during transportation, casualty coverings must provide adequate thermal insulation and protection against cold, wind, moisture, and water splashes.

OBJECTIVE

The aim of this study was to determine the thermal protective properties of different types of casualty coverings and to evaluate which would be adequate for use under difficult maritime conditions (cold, high wind speed, and water splashes). In addition, the study evaluated the need for thermal protection of a casualty and verified the optimum system for maritime casualty transportation.

METHODS

The study consisted of two parts: (1) the definition and comparison of the thermal protective properties of different casualty coverings in a laboratory; and (2) the evaluation of the chosen optimum protective covering for maritime prehospital transportation. The thermal insulations of ten different casualty coverings were measured according to the European standard for sleeping bags (EN 13537) using a thermal manikin in a climate chamber (-5°C) with wind speeds of 0.3 m/s and 4.0 m/s, and during moisture simulations. The second phase consisted of measurements of skin and core temperatures, air temperature, and relative humidity inside the clothing of four male test subjects during authentic maritime prehospital transportation in a partially-covered motor boat.

RESULTS

Wind (4 m/s) decreased the total thermal insulation of coverings by 11%-45%. The decrement of thermal insulation due to the added moisture inside the coverings was the lowest (approximately 22%-29%) when a waterproof reflective sheet inside blankets or bubble wrap was used, whereas vapor-tight rescue bags and bubble wrap provide the most protection against external water splashes. During authentic maritime transportation lasting 30 minutes, mean skin temperature decreased on average by 0.5°C when a windproof and water-resistant rescue bag was used over layered winter clothing.

CONCLUSION

The selected optimum rescue bag consisted of insulating and water-resistant layers providing sufficient protection against cold, wind, and water splashes during prehospital transportation lasting 30 minutes in the uncovered portion of a motor boat. The minimum thermal insulation for safe maritime transportation (30 minutes) is 0.46 m²K/W at a temperature of -5°C and a wind speed of 10 m/s.