Assessment of gas flow waves for endotracheal tube placement in an ovine model of neonatal resuscitation

Aim

Clinical assessment and end-tidal CO₂ (ETCO₂) detectors are routinely used to verify correct endotracheal tube (ETT) placement. However, ETCO₂ detectors may mislead clinicians by failing to correctly identify placement of an ETT under a variety of circumstances. A flow sensor measures and displays gas flow in and out of an ETT. We compared endotracheal flow sensor recordings with a colorimetric CO₂-detector (Pedi-Cap^®) to detect endotracheal intubation in a preterm sheep model of neonatal resuscitation.

Methods

Six preterm lambs were intubated and ventilated immediately after delivery. At 5 min the oesophagus was also intubated with a similar tube. The endotracheal tube and oesophageal tubes were attached to a Pedi-Cap^® and flow sensor in random order. Two observers, blinded to the positions of the tubes, used a ETCO₂ detector and the flow sensor recording to determine whether the tube was in the trachea or oesophagus. The experiment was repeated 10 times for each animal. In the last three animals (30 recordings) the number of inflations required to correctly identify the tube placement was noted.

Results

The Pedi-Cap^® and the flow sensor correctly identified tube placement in all studies. Thus, the sensitivity, specificity, and positive and negative predictive values of both devices were 100%. At least three, and up to 10, inflations were required to identify tube location with the Pedi-Cap^® compared to one or two inflations with the flow sensor.

Conclusion

A flow sensor correctly identifies tube placement within the first two inflations. The Pedi-Cap^® required more inflations to correctly identify tube placement.