Variable apparatus deadspace

Evaluation the effect of breathing filters on end-tidal carbon dioxide during inferior abdominal surgery in infants and changes of tidal volume and respiratory rate needs for preventing of increasing end-tidal carbon dioxide

Background:

The aim of this study was to prevent of increasing end-tidal carbon dioxide (ETCO₂₎ with changing of vital capacity and respiratory rate when using of birthing filter in infants.

Materials and Methods:

In a randomized clinical trial study, ninety-four infant’ patients were studied in three groups. Basic values, such as peak inspiratory pressure, tidal volume, minute ventilation, respiratory rate, and partial pressure of ET CO₂ (PETCO₂) level had been evaluated after intubation, 10 min after intubation and 10 min after filter insertion. In the first group, patients only observed for changing in ETCO₂ level. In the second and the third groups, respiratory rates and tidal volume had been increased retrospectively, until that ETCO₂ ≤35 mmHg was received. We used ANOVA, Chi-square, and descriptive tests for data analysis. P < 0.05 was considered statistically significant.

Results:

Tidal volume 10 min after filter insertion was statistically higher in Group 3 (145.0 ± 26.3 ml) versus 129.3 ± 38.9 ml in Group 1 and 118.7 ± 20.8 ml in Group 2 (P = 0.02). Furthermore, respiratory rate at this time was statistically higher in Group 2 (25.82 ± 0.43) versus Groups 1 and 3 (21.05 ± 0.20 ml and 21.02 ± 0.60 ml, respectively) (P = 0.001). Minute volume and PETCO₂ level were statistically significant between Group 1 and the other two groups after filter insertion (P = 0.01 and P = 0.00,1 respectively).

Conclusion:

With changing the vital capacity and respiratory rate we can control PETCO₂ level ≤35 mmHg during using of birthing filters in infants. We recommend this instrument during anesthesia of infants.

Control of end-tidal carbon dioxide during IPPV. Variable functional apparatus deadspace

We have described a method for control of end-tidal carbon dioxide tension during intermittent positive pressure ventilation in a model lung and in 19 adults during general anaesthesia supplemented by central or peripheral neural blockade. The inspiratory and expiratory limbs of an open or a circle anaesthesia system were interconnected and ventilated simultaneously in a variable manner during inspiration. The flow of mixed-expired gas, normally one-way, became to-and-fro (variable functional apparatus deadspace, or "virtual' deadspace). At minute volume ventilation > or = 100 ml.kg-1.min-1 (patients), the value of end-tidal carbon dioxide tension was varied reproducibly within the range 4.1-6.5 (SD 0.1)kPa independently of fresh gas flow or other prescribed patterns of ventilation. At a steady state, stable nominated values of end-tidal carbon dioxide tension within the range were attained. By how much any given intra-operative value of end-tidal carbon dioxide tension may be said to affect peri-operative outcome is debatable, but during surgery any change in a nominated value may usefully indicate a change in the steady state.