Inferior Alveolar Nerve Block Using the Anterior Technique to Anesthetize Buccal Nerve and Improve Anesthesia Success Rates for Third Molar Extraction: A Randomized Controlled Trial and Magnetic Resonance Imaging Evaluation.

PURPOSE: The lack of anesthesia to the buccal nerve and an insufficient volume of anesthetic have been reported to be responsible for failed inferior alveolar nerve blocks (IANBs) using the Halsted approach (conventional IANB). We aimed to determine the extent of anesthesia in the buccal nerve innervation area and evaluate the anesthetic efficacy of injecting a larger volume of anesthetic during IANB using the anterior approach (anterior technique) in the clinical setting and with magnetic resonance imaging (MRI) analysis. PATIENTS AND METHODS: The prospective randomized controlled trial included patients scheduled for removal of a mandibular third molar. The primary predictor variables were the approach for IANB (anterior technique vs conventional IANB) and anesthetic dose (1.8 vs 2.7 mL). The primary outcome variables were the extent of anesthesia and the anesthesia success rate, defined as completion without additional anesthesia. The secondary outcome variable was the anesthetic drug distribution related to the pterygomandibular space measured on T2-weighted MRI scans. Statistical independence of the anesthesia success rate among the primary predictor variables was tested with statistical significance set at P ≤ .05. RESULTS: A total of 108 patients and 10 volunteers were enrolled in the clinical and MRI studies, respectively. Anesthesia of the buccal nerve was evident in patients receiving the anterior technique with 2.7 mL of anesthetic. The success rate of the anterior technique with 2.7 mL of anesthetic (96%) was greater than that with 1.8 mL of anesthetic (67%; P = .0113), and increasing the dose had no effect on the efficacy of conventional IANB (78% vs 81%; P = 1.000). The MRI study showed that the anesthetic was distributed over the anterior surface of the temporalis tendon and in the pterygomandibular space after the anterior technique. CONCLUSIONS: Anesthesia of the buccal nerve using the anterior technique with 2.7 mL of anesthetic solution might contribute to increasing the success rate of anesthesia for removal of mandibular third molars.

Possible association between successful intubation via the right nostril and anatomical variations of the nasopharynx during nasotracheal intubation: a multiplanar imaging study.

PURPOSE: Most reported cases of nasopharyngeal laceration following impingement during nasotracheal intubation involved tube insertion via the right nostril. We postulated that recesses on the posterior wall of the nasopharynx might be associated with tube impingement. Using multiplanar imaging and clinical statistics, we evaluated whether anatomical variations in the recesses are related to successful intubation via the right nostril. METHODS: Using multiplanar computed tomography (CT) images of 97 patients, we investigated the locations of recesses relative to the mid-sagittal plane, nasal floor plane and posterior end of the nasal septum, and their shapes. Incidents of impingement of the tube during nasotracheal intubation and the shapes of the fossa of Rosenmüller on CT images were retrospectively evaluated in 170 patients. RESULTS: Eustachian tube orifices were located approximately 10 mm laterally from the sagittal plane, and approximately 10 mm above the nasal floor plane. The fossa of Rosenmüller was vertically elongated and located 7 mm laterally from the mid-sagittal plane. Pharyngeal bursae were found in 15 % of the subjects. Patients with failed insertion via the right nostril due to impingement frequently had a wide opening of the fossa of Rosenmüller. CONCLUSIONS: Successful intubation via the right nostril is related to the anatomy of structures on the posterior nasopharyngeal wall, particularly recesses located close to the path of nasotracheal tube insertion. Nasopharyngeal anatomical variations should be considered when one notices any resistance to advancement of the tube into the nasopharynx during nasotracheal intubation.

Three-dimensional CT image analysis of a tracheal bronchus in a patient undergoing cardiac surgery with one-lung ventilation.

The incidence of a tracheal bronchus--that is, a congenitally abnormal bronchus originating from the trachea or main bronchi--is 0.1%-2%. Serious hypoxia and atelectasis can develop in such patients with intubation and one-lung ventilation. We experienced a remarkable decrease in peripheral oxygen saturation (SpO2) and a rise in airway pressure during placement of a double-lumen endobronchial tube in a patient with patent ductus arteriosus and tracheal bronchus. Substitution of the double-lumen tube with a bronchial blocker tube provided secure isolation of the lung intraoperatively. A type I tracheal bronchus and segmental tracheal stenosis were identified on postoperative three-dimensional (3D) computed tomographic (CT) images. Preoperative examination of chest X-rays, CT images, and preoperative tracheal 3D images should preempt such complications and assist in securing safe and optimal one-lung ventilation.