Evaluation of a Nasoenteral Feeding Tube With Balloon to Facilitate Placement.

BACKGROUND: Enteral feeding is essential for critically ill, head trauma, and burn patients who are unable to swallow. OBJECTIVE: To evaluate a new nasoenteral feeding tube with distal tip balloon designed to facilitate post-pyloric migration and avoid misplacement in the trachea. METHODS: A case series was conducted in 50 critically ill patients aged 19 to 89 years receiving mechanical ventilation and requiring enteral nutrition in a teaching hospital. Patients received a soft, flexible, kink-resistant nasoenteral feeding tube with a balloon near the distal tip to enhance postpyloric migration by peristalsis. The feeding tube was inserted with a novel thread technique to reduce posterior nasopharyngeal trauma and tube misplacement. Pulse oximetry provided early detection of misplacement into the trachea. Placement was verified by abdominal radiography performed shortly after the procedure and repeated within 24 hours if needed. RESULTS: Postpyloric placement was achieved at 30 minutes in 24% of patients and by the following morning in 70% of patients. Tracheal intubation occurred in 1 patient but was recognized and corrected without injury. No tube occlusion from kinking occurred. CONCLUSIONS: Early gastric or postpyloric feeding can be provided with this novel feeding tube. Its use facilitates quick bedside recognition of accidental misplacement in the trachea, reducing the chance of pneumothorax. The tip balloon reduces deeper placement into a lung and promotes distal migration into the small intestine. The design prevents occlusion from kinking, which is common with conventional feeding tubes. Nurses easily adopted the tube and insertion technique.

Protease-activated receptor-2 inhibits BK channel activity in bronchopulmonary sensory neurons.

Activation of protease-activated receptor-2 (PAR2) contributes to airway inflammation and airway hypersensitivity, the hallmark features of allergic asthma; and a neurogenic mechanism involving hypersensitivity of bronchopulmonary sensory nerves has been indicated. Large-conductance Ca(2+)-activated potassium (BK) channels are known to play an important role in shaping neuronal excitability. The aim of this study was to investigate the potential regulation of BK channel activities by PAR2 activation in vagal bronchopulmonary sensory neurons. Our results showed that pretreatment with PAR2-activating peptide (PAR2-AP; 100µM, 120s), but not its control peptide PAR2-RP, significantly reduced BK current density in these neurons. Inhibition of phospholipase C, PKC, PKA or MEK/ERK signaling pathway did not prevent the suppression of BK current by PAR2 activation; whereas intracellular application of Ca(2+) chelator BAPTA-AM completely abolished the PAR2 regulation of BK current. In addition, our results demonstrated that activation of PAR2 increased excitability of bronchopulmonary sensory neurons, in a similar manner as displayed by a direct BK channel blockade. In summary, our data suggest that suppression of BK channel activity contributes to PAR2 activation-induced hyperexcitability of vagal bronchopulmonary sensory neurons.

Modulation of BK channel activities by calcium-sensing receptor in rat bronchopulmonary sensory neurons.

This study was carried out to investigate the expression of large-conductance Ca(2+)-activated potassium (BK) channels and to explore the possible modulation of BK channel activities by calcium-sensing receptors (CaSR) in rat bronchopulmonary sensory neurons. The expression of BK channels was demonstrated by immunohistochemistry and RT-PCR. Results from whole-cell patch-clamp recordings demonstrated that activation of CaSR with its agonist spermine or NPS R-568 showed a dual regulating effect on BK channel activities: it potentiated BK currents in cells exhibiting low baseline BK activity while slightly inhibited BK currents in cells with high baseline BK activity. Blocking CaSR with its antagonist NPS 2143 significantly inhibited BK currents. Our results further showed that the modulation of BK currents by CaSR activation or blockade was completely abolished when the intracellular Ca(2+) was chelated by BAPTA-AM. In summary, our data suggest that CaSR plays an integrative role in bronchopulmonary afferent signaling, at least partially through the regulation of BK channel activities.

Placement of nasoenteral feeding tubes using external magnetic guidance.

BACKGROUND: Enteral feeding is preferred over parenteral methods, and feeding into the duodenum is preferred over gastric feeding in certain groups of critically ill patients. However, with current techniques, feeding tubes often coil in the stomach, exposing patients to the risk of aspiration. This study investigated whether a nasoenteral feeding tube can be guided beyond the pyloric sphincter, using external magnetic guidance. METHODS: This is a case series of 288 critically ill patients who needed placement of an enteral feeding tube, carried out in the intensive care units and wards of a university-affiliated community hospital. A 12-French polyurethane nasoduodenal feeding tube was modified by placing a small magnet in the distal tip. After inserting the tube through the nares into the esophagus, an external magnet was used to draw the tube tip beyond the pyloric sphincter and further into the duodenum or jejunum. Placement was verified by plain abdominal x-ray, and the depth of insertion (stomach, proximal duodenum, distal duodenum, or jejunum) was recorded. RESULTS: Three hundred twenty-nine intubations were performed in 288 patients (mean procedure time 15 minutes). In 293 cases (89.1%), the tube was placed beyond the pyloric sphincter. In 139 insertions (42.2%), the tube tip was in the distal portion of the duodenum or the jejunum. There were no significant complications. CONCLUSIONS: This case series demonstrates that external magnetic guidance achieves transpyloric placement of an enteral feeding tube in 89.1% of cases. This reliable bedside technique is superior to other methods described in the literature.