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KMID : 0385019990150020213
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Korean Journal of Laboratory Animal Science
1999 Volume.15 No. 2 p.213 ~ p.219
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Effect of Apparatus Deadspace on Ventilatory Efficiency During Controlled Ventilation in Enflurane-Anesthetized Rats
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김종성/Kim, Jong Sung
한진수/김휘율/Han, Jin Soo/Kim, Hwi Yool
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Abstract
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The purpose of present study is to investigate the effect of an added apparatus deadspace on ventilatory efficiency in rats during controlled ventilation. Twenty SD rats(mean weight 319±11g) were rando㎖y allocated into 4 groups according to the volume of an added apparatus(V^(appa)_D) deadspace. Four groups were divided into Control group(no added V^(appa)_D), Group I(tube length: gem, V^(appa)_D: 0.25㎖), Group B (tube length : 4㎝, V^(appa)_D : 0.5㎖), and Group III (tube length : 9㎝, V^(appa)_D: 1.13㎖). Anesthesia was induced with pear tobarbital sodium and induction chamber. After tracheal cannulation, animals were ventilated with small animal ventilator. Inhalational anesthesia was maintained with enflurane/oxygen(100%)/pancuronium. When a stable state of eucapnia(38±4mmHg) was achieved, the silicon tubes(ID 4㎜) of the different length were inserted between the endotracheal tube and the Y-piece of the ventilator for increase of apparatus dead space. Hemodynamic parameters were measured at baseline and after 20, 40, 60, 80, 100, and 120 minutes during controlled ventilation. Increased apparatus deadspace produced a significant(p$lt;0.08) increase in PaCO₂. After a deadspace ventilation period of 120 minutes, PaCO₂ of Group II and III increase up to 74.1±10.3mmHg and 169.1±18.7mmHg, respectively. We conclude that adding an apparatus deadspace to de crease alveolar ventilation(ventilatory efficiency) may result in severe hypercapnia, respiratory acidosis, and ventilatory failure in the rats due to a rebreathing of aspired CO₂. We suggest that an apparatus dead space between the endotracheal tube and the Y-piece of the ventilator should be minimized possibly during controlled ventilation in small experimental animals for reducing the rebreathing of aspired CO₂.
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