The Science Journal of the American Association for Respiratory Care
Introduction: Debate continues among clinicians regarding the merits of self-inflating (SI) and non self-inflating (NSI) bags. We sought to compare the variability of ventilation between the two bags in a neonatal lung model.
Methods: We compared a SI type (Baxter) and NSI type bag (Drager, Rusch). We tested 5 RCPs and 20 nurses on each bag type. We used a Siemens test lung with a pressure manometer. Subjects were asked to achieve PIP=30, PEEP=4, f=30. PEEP was controlled on the SI bag by using a PEEP valve, and on the NSI by controlling flow into and out of the bag. Data were gathered for 8-10 minutes. PIP and PEEP were measured and stored via computerized pneumotachography (Ventrak, Novametrix Inc.). Results: 8717 breaths were analyzed. The distribution of PIP and PEEP sorted by bag type are described in figure 1. We found statistically significant differences in PIP, PEEP and frequency between the two bag types (Mann-Whitney U test all P values < 0.01). Mean ± SD and Coefficients of Variation (SD/Mean) are represented in table 1.
|Non self-inflating bag||26.0||(±2.3)||(0.182)||3.0||(±1.9)||(0.641)|
|Table 1: PIP and PEEP Mean ± SD and Coefficients of Variation (CV)|
Discussion: We found statistical significance between bag types but felt that these differences were not clinically important for PIP. Differences in PEEP were more concerning. It is interesting to note that the NSI bag yielded significantly more breaths under all conditions that were far below the 10th percentile for PIP, suggesting a greater variability of ventilation with the NSI type bags. This is also demonstrated by the much higher coefficients of variation for both PIP and PEEP for the NSI bag. This suggests that maintaining stable ventilatory parameters is more difficult with a NSI bag.
(See Original for Figure)