Retropharyngeal Dissection by Parker Flex-Tip Nasal Endotracheal Tube.

Possible complications of nasotracheal intubation include injury to the nasal or pharyngeal mucosa. Dissection of the retropharyngeal tissue by the endotracheal tube is one of the rarer of the more severe complications. Previous studies have indicated that the Parker Flex-Tip (PFT) tracheal tube (Parker Medical, Highlands Ranch, Colo) reduces the incidence of mucosal injury. We experienced a case involving inadvertent retropharyngeal placement of a PFT tube in a 29-year-old patient during nasotracheal intubation under general anesthesia for elective dental treatment. Despite thermosoftening the PFT tube, expanding the nasal meatus, and ensuring gentle maneuvering, the tube intruded into the left retropharyngeal mucosa. However, the injury was not severe, and the only required treatment was the administration of antibiotics and corticosteroids. Even when a PFT tube is utilized, pharyngeal dissection is possible. When resistance is felt during passing of the PFT tube through the nasopharynx, an alternative method to overcome this resistance should be utilized.

Novel trigeminal slice preparation method for studying mechanisms of nociception transmission.

BACKGROUND: The trigeminal subnucleus caudalis (Vc) plays a critical role in transmission and modulation of nociceptive afferent inputs, and exhibits a similar layer construction to the spinal dorsal horn. However, afferent inputs enter the brainstem and project to a separately located nucleus. It has previously been difficult to record responses of the Vc to afferent fiber activation in a brainstem slice preparation. The aim of the present study was to establish a novel brainstem slice preparation method to study trigeminal nociceptive transmission mechanisms. NEW METHOD: Thirty adult 6-7-week-old C57/BL6J male mice were included in the study. Obliquely sliced brainstem sections at a thickness of 600µm, which included the Vc and the root entry zone to the brainstem, were prepared. The Vc response to electrical stimulation of afferent fibers was observed as a change in intracellular calcium concentration by fluorescence intensity response. RESULTS: Electrical stimulation of afferent inputs to the trigeminal nerve increased fluorescent intensity in the Vc, which was completely diminished by tetrodotoxin and significantly suppressed by the AMPA/kainate antagonist CNQX (paired t-test, P<0.001), although the non-competitive NMDA antagonist (+)-MK801 maleate resulted in no changes. These results suggested a glutamate receptor-mediated response. COMPARISON WITH EXISTING METHODS/CONCLUSION: This brainstem slice preparation will be useful for investigating nociceptive transmission mechanisms of the trigeminal nerve.