Quality Improvement: Diagnostic Accuracy of Mainstream Versus Sidestream Capnography in Detecting Airway Intubation of Small-Bore Styleted Nasoenteric Feeding Tubes in Dogs and Cats

Objective

To evaluate the diagnostic accuracy of sidestream and mainstream capnography to detect misplacement of small-bore, styleted nasoenteric (NE) feeding tubes into the respiratory tract of dogs and cats.

Design

Prospective study from February 2020 to November 2020.

Setting

University teaching hospital.

Animals

Ten dogs and 10 cats undergoing elective surgical procedures.

Interventions

Under general anesthesia, an NE feeding tube attached to a handheld sidestream (dogs and cats) then mainstream capnograph (dogs) was inserted into the patient's endotracheal (ET) tube. Respiratory rate, end-tidal carbon dioxide (ETCO₂), and time to ETCO₂ waveform were recorded.

Measurements and Main Results

Mainstream capnography failed to detect an ETCO₂ reading or respiratory waveform in all dogs evaluated. In dogs and cats, sidestream capnography accurately detected ETCO₂ measurement, respiratory rate, and waveform within 4 s of feeding tube insertion into the ET tube, with ETCO₂ readings >35 mm Hg in all dogs and >20 mm Hg in all cats. ETCO₂ readings obtained from the NE tubes were similar to but did not match those obtained by the anesthesia monitoring equipment for dogs and cats. Sidestream capnography accurately detects airway intubation with small-bore, styleted NE tubes in dogs and cats, regardless of patient size. Further studies are required to determine whether this method could be used in awake and sedated patients in real time to detect airway intubation during placement of NE tubes.

Conclusions

Sidestream capnography is able to detect misplacement of small-bore, styleted feeding tubes into the respiratory tract of dogs and cats regardless of patient size. This technique shows promise as a tool to reduce respiratory complications of feeding tube placement in veterinary patients.