Author/Editor		Mekjavić, Igor B
Title		Ventilacija podhlajenih: usta na usta ali dihalni balon?
Translated title		Artificial ventilation of hypothermic patients in the field: mouth-to-mouth or bag-valve-mask?
Type		članek
Source		Med Razgl
Vol. and No.		Letnik 41, št. 2-3
Publication year		2002
Volume		str. 195-9
Language		slo
Abstract		This study evaluated the benefits of a heat and moisture exchanger in the oro-nasal mask of a ventilating balloon for resuscitation in sub-zero ambients. Specifically, it tested the hypothesis that the reduction of respiratory heat loss would be similar to that achieved with mouth-to-mouth resuscitation. The prototype respiratory heat and moisture exchanger developed to minimise respiratory heat loss in subzero ambients was evaluated at ambient temperatures (Ta) of -20degreesC, -10degreesC, 0degreesC,10degreesC and 20degreesC. It comprised a thermally insulated oro-nasal mask with a cylindrical heat and moisture exchanging unit protruding from the centre of the mask. The heat exchanging unit contains a »honeycomb" aluminium structure, providing a total surface area of 478.5 cm2 for the exchange of heat and moisture between the inhaled and exhaled air. A simulator comprising a hydraulically driven pump and a humidifier provided a ventilatory rate of 11.25 L/min. The simulated exhaled volume of air was maintained at approximately 37 degrees C and saturated with water vapour. The HME was strapped to the head of a manikin, whose mouth was connected to the respiratory simulator. The entire arrangement was placed in a climatic chamber maintained at the desired temperature. At ambient temperatures ranging from -24degreesC to +22degreesC, the HME elevated the temperature of the inhaled air to within the range of +22degreesC to +29degreesC. The humidity of the inhaled air was maintained at 100% in all conditions. The results indicate that the HME effectively reduces respiratory heat loss in ambient conditions ranging from -20 to +20degreesC. An oro-nasal mask incorporating a heat and moisture exchanger would therefore be capable of significantly reducing respiratory heat loss during ventilation of hypothermic victims.
Summary		Pri ventilaciji podhlajenih reševalci pogosto uporabljajo metodo usta na usta namesto dihalnega balona, ker so mnenja, da z metodo usta na usta preprečujejo nadaljnjo toplotno izgubo iz pljuč. Ta metoda ni vedno praktična, predvsem na primer pri reševanju v visokogorju: S pričujočo raziskavo smo ovrednotili učinkovitost izmenjevalca toplote in vlage, ki bi, vgrajen v ustnonosno masko; zmanjšal dihalne toplotne izgube ponesrečencev med ventilacijo v mrzlem okolju. Prototip izmenjevalca toplote in vlage smo ovrednotili pri simuliranih pogojih v klimatski komori, v kateri smo vzdrževali temperaturo zraka -20 stopinj, -10stopinj, 0 stopinj, +10 stopinj in +20 stopinj C. Izmenjevalec toplote in vlage ima aluminijasto satovje, ki ponuja površino 487,5 cm2 za izmenjavo toplote. Izdihani zrak segreje aluminijasto satovje in pri ohlajanju se vlaga v izdihanem zraku utekočini. Kondenz je tako ujet v satovju. Pri vdihu izmenjevalec toplote segreje vdihani zrak in ga ovlaži. Toplota in vlaga v izdihanem zraku se preneseta na volumen zraka, ki ga vdahnemo pri naslednjem vdihu. Ustnonosno masko z izmenjevalcem toplote in vlage smo namestili na usta lutke, ki smo jih s cevjo povezali na simulator dihanja. Simulator je posnemal dihanje z minutnim volumnom 11,25 L/min. Izdihani zrak simulatorja je imel temperaturo 37 stopinj C in 100% relativno vlago. Med poskusi smo v različnih pogojih merili temperaturo v ustnonosni maski. Pri temperaturi -24 stopinj C je izmenjevalee toplote in vlage vzdrževal temperaturo zraka v ustnonosni maski nad +22 stopinj C. Pod vsemi pogoji je bil zrak v ustnonosni maski 100 % nasičen z vlago. Rezultati dokazujejo, da je prototip izmenjevalca tbplote in vlage sposoben značilno zmanjšati respiratorne izgube toplote v temperaturnem območju -20 stopinj do +20 stopinj C. Ustnonosna maska s tako vgrajenim izmenjevalcem toplote in vlage lahko značilno zmanjša toplotne izgube med ventilacijo podhlajenih z dihalim balonom.
Descriptors		HYPOTHERMIA REWARMING RESUSCITATION LARYNGEAL MASKS