Abstract Background Pulmonary macro/micro aspiration of gastric contents is implicated in the pathogenesis of lung injury in intubated/ventilated patients and associated mortality. Anesthetic agents, sedatives and opiates relax lower esophageal sphincter (LES) leading to acute gastroesophageal reflux (AGER), anti-acids lead to bacterial overgrowth and these are often found as causative organisms in these patients. CDC guidelines recommend using gravity (head elevation) as a central strategy to mitigate this risk, but compliance remains variable. We present neuromodulation of LES which potentially could prevent AGER and lung injury in intubated patients. Methods Polyurethane tubes (10 Fr diameter) incorporating 46, 200 micron gold electrodes, MEMS pressure sensor and radio-opaque markings were used for stimulation (biphasic square wave with 200 us pulse width) at 2-30 mAmp controlled by a custom stimulator. Extensive in-vitro tests were conducted to standardize pulse wave duration. Four domestic pigs intubated and ventilated, in supine position underwent placement of 10 Fr catheters under vision orally and the electrodes were positioned under X-ray guidance in the vicinity of the LES. Aim was to effect 10 cm of water (H2O) pressure increases over the baseline (pre-stimulation) pressure by increasing the simulation current, to assure closed status of LES and stop AGER. Results LES pressures: Pre-stimulation: 20±2 cm of H2O, post-stimulation: 40±4 cm of H20, on average was obtained with 20mA stimulation. No adverse events in terms of arrythmia or diaphragmatic contractions observed for the duration of experiment. Minimum current to increase LES pressure was 14 mA and the response saturated for stimulation strength above 20 mA. The results could be repeated for a continuous stimulation lasting half an hour (4 hrs/each animal). Conclusion An esophageal pressure differential over gastric pressure can be achieved using neuromodulation for maintaining LES tone and possibly stop reflux of gastric contents. This has the potential to prevent and address one of the important elements in the causation of acute lung injury in intubated patients. This abstract is funded by: PiroGon Inc
Bonde et al. (Fri,) studied this question.