Korean J Crit Care Med.  2004 Dec;19(2):126-129.

Comparison of Ventilations with LMA and Endotracheal Tube during Closed Circuit Anesthesia

• Shin IW
• Park KE
• Chung HD
• Sohn JT
• Lee HK
• Chung YK

Abstract

BACKGROUND
LMA has larger dead-space than tracheal tube, ventilation may be influenced by difference of dead space. Closed circuit mechanical ventilation has high risk of hypercarbia because of inadequate CO2 elimination or gas supply. Thus, end-tidal carbon dioxide tension (EtCO2) and arterial carbon dioxide tension (PaCO2) were compared during closed circuit mechanical ventilation with LMA or tracheal tube. METHODS: Thirty adult patients scheduled for general anesthesia were divided into 2 groups. After induction of general anesthesia, laryngeal mask airway (Group 1, n=15) or tracheal tube (Group 2, n=15) were randomly inserted and closed circuit mechanical ventilation was initiated. When steady state had been reached, PaCO2 and EtCO2 were recorded. RESULTS: The PaCO2 was 32.2+/-2.8 (Group 1), 31.5+/-2.2 (Group 2) and the EtCO2 was 33.0+/-2.9, 31.6+/-2.4 respectively and there was no statistical significance between groups. The difference of arterial and end-tidal carbon dioxide tension in each group was -0.8+/-2.6, -0.03+/-2.2 respectively and there was no statistical significance between groups. CONCLUSIONS: The results indicate that in patients who are mechanically ventilated via the closed circuit system, EtCO2, PaCO2, and the difference between arterial and end-tidal carbon dioxide tension were not significantly different between groups.

Keyword

Carbon dioxide tension; Closed circuit anesthesia; Laryngeal mask airway; Tracheal tube

MeSH Terms

Adult
Anesthesia, Closed-Circuit*
Anesthesia, General
Carbon Dioxide
Humans
Laryngeal Masks
Respiration, Artificial
Ventilation*
Carbon Dioxide