Injectate spread in ultrasound-guided inferior alveolar nerve block: a cadaveric study.

PURPOSE: Ultrasound-guided inferior alveolar nerve block (UGIANB) is a mandibular analgesic procedure in which local anesthetic is injected into the pterygomandibular space (PMS). Several studies have reported the clinical efficacy of UGIANB for mandibular surgeries; however, its effective range has never been investigated. We performed a cadaveric study to investigate the success rate of UGIANB injections and to determine whether injected dye could stain the mandibular nerve (MN) trunk and its branches. METHODS: We performed UGIANB on the bilateral faces of 4 Thiel-embalmed cadavers. A needle was advanced to the PMS under ultrasound guidance and 5 mL of dye was injected. The cadaver was dissected and inspected for the presence of dye in the PMS; the range of dye spread to any of the inferior alveolar nerve (IAN), lingual nerve (LN), buccal nerve (BN), mandibular nerve (MN), auriculotemporal nerve (ATN), or facial nerves; and for the presence of intravascular dye. RESULTS: We performed eight UGIANB procedures on four cadavers. Dye was observed in the PMS in 7/8 injections. Staining was observed in all IAN, LN, and BNs that could be identified at dissection. No MN or auriculotemporal nerves (ATNs) were stained in any injections. No intravascular dye was observed in any injections. CONCLUSIONS: UGIANB can administer anesthetic into the PMS with high accuracy. UGIANB injections reached the IAN, LN, and BNs, but did not reach the MN or ATNs located outside the PMS. The findings of this cadaveric study indicate that UGIANB can provide sufficient analgesia for mandibular surgeries.

Head Rotation Reduces Oropharyngeal Leak Pressure of the i-gel and LMA® Supreme™ in Paralyzed, Anesthetized Patients: A Randomized Trial.

BACKGROUND: Second-generation supraglottic airway (SGA) devices are useful for airway management during positive pressure ventilation in general anesthesia and emergency medicine. In some clinical settings, such as the anesthetic management of awake craniotomy, SGAs are used in the head-rotated position, which is required for exposure of the surgical field, although this position sometimes worsens the efficiency of mechanical ventilation with SGAs. In this study, we investigated and compared the influence of head rotation on oropharyngeal leak pressures (OPLP) of the i-gel and LMA® Supreme™, which are second-generation SGA devices. METHODS: Patients who underwent elective surgery under general anesthesia were enrolled in this study and randomly divided into i-gel or LMA Supreme groups. After induction of anesthesia with muscle relaxation, the i-gel or LMA Supreme was inserted according to computerized randomization. The primary outcome was the OPLP at 0°, 30°, and 60° head rotation. The secondary outcomes were the maximum airway pressure and expiratory tidal volume when patients were mechanically ventilated using a volume-controlled ventilation mode with a tidal volume of 10 mL/kg (ideal body weight), ventilation score, and fiber-optic views of vocal cords. RESULTS: Thirty-four and 36 participants were included in the i-gel and LMA Supreme groups, respectively. The OPLPs of the i-gel and LMA Supreme significantly decreased as the head rotation angle increased (mean difference [95% confidence interval], P value: i-gel; 0° vs 30°: 3.5 [2.2-4.8], P < .001; 30° vs 60°: 2.0 [0.6-3.5], P = .002; 0° vs 60°: 5.5 [3.3-7.8], P < .001, LMA Supreme; 0° vs 30°: 4.1 [2.6-5.5], P < .001; 30° vs 60°: 2.4 [1.1-3.7], P < .001; 0° vs 60°: 6.5 [5.1-8.0], P < .001). There were statistically significant differences in expiratory tidal volume and ventilation score between 0° and 60° in the i-gel group and in ventilation score between 30° and 60° in the LMA Supreme group. There was no statistically significant difference between the 2 devices in all outcome measures. The incidences of adverse events, such as hoarseness or sore throat, were not significantly different between i-gel and LMA Supreme. CONCLUSIONS: Head rotation to 30° and 60° reduces OPLP with both i-gel and LMA Supreme. There is no difference in OPLP between i-gel and LMA Supreme in the 3 head rotation positions.

Mouth-Opener Technique for Ultrasound-Guided Inferior Alveolar Nerve Block: A Case Series of Extraction of Impacted Mandibular Third Molars.

Extraction of the impacted mandibular third molar (IMTM) is common in oral surgery, but its postoperative pain is severe. Ultrasound-guided inferior alveolar nerve block (UGIANB) is an analgesic technique in the mandibular nerve region. We describe UGIANB using a mouth opener and report the cases with a good postoperative course. Six patients underwent the extraction of bilateral IMTMs under general anesthesia. After surgery, we performed UGIANB and administered 5 mL of 0.375% levobupivacaine on each side. The postoperative numerical rating scale pain scores were 1 (0-2) and 2.5 (0-5) (mean (range)), postoperative day one and seven, respectively. The postoperative quality of recovery-40 scores were 188.5 (8.1) and 191.7 (7.6) (mean (SD)), postoperative day one and seven, respectively. No procedural complications were encountered. We performed UGIANB with a mouth opener on a patient with IMTM extraction and were able to provide safe and good analgesia.

Modified thoracoabdominal nerve block through perichondrial approach (M-TAPA): an anatomical study to evaluate the spread of dye after a simulated injection in soft embalmed Thiel cadavers.

BACKGROUND AND OBJECTIVES: There is still no consensus on the analgesic range and mechanisms of action of modified thoracoabdominal nerve block through perichondrial approach (M-TAPA). This cadaveric study aimed to determine the spread of an injectate following simulated M-TAPA. METHODS: Simulated M-TAPA injections (n=8) were administered on both sides of soft embalmed Thiel cadavers with 25 mL of a saline-soluble dye. Anatomic dissection was performed to document staining (deeply, faintly, or not stained) of the anterior cutaneous branches of the thoracoabdominal nerves and determine the extent of the injectate spread of the dye to the intercostal space in the thoracic cage following a simulated M-TAPA. RESULTS: The median (IQR) dermatome of the stained segmental nerve was T10 (T8-T11) and the median (IQR) number of stained segmental nerves was 3 (4-2). The T9, T10 and T11 segmental nerves were stained in 75%, 100% and 62.5% of simulated M-TAPA, respectively. Conversely, the T8 segmental nerve was stained in only 25% of simulated M-TAPA. No injectate spread of dye to the intercostal space in the thoracic cage was observed in eight simulated injections of M-TAPA. CONCLUSION: Our findings suggest that M-TAPA most likely involves the T9, T10 and T11 segmental nerves and that the local anesthetic may not spread to the intercostal space in the thoracic cage in M-TAPA. Further studies are required to confirm the precise mechanism of action and efficacy of M-TAPA in a large sample of human participants.

I-gel Plus acts as a superior conduit for fiberoptic intubation than standard i-gel.

The supraglottic airway (SGA) is widely used. I-gel Plus is a next-generation i-gel with some improvements, including facilitation of fiberoptic tracheal intubation (FOI). To compare the performance of i-gel Plus and standard i-gel as conduits for FOI, a Thiel-embalmed cadaveric study was conducted. Twenty-two anesthesiologists were enrolled as operators in Experiment 1. The i-gel Plus and standard i-gel were inserted into one cadaver, and the FOI was performed through each SGA. The primary outcome was time required for FOI. The secondary outcomes were the number of attempts and visual analog scale (VAS) score for difficulty in FOI. Moreover, fiberoptic views of the vocal cords in each SGA were assessed by an attending anesthesiologist using nine cadavers in Experiment 2. The percentage of glottic opening (POGO) score without fiberscope tip upward flexion and upward angle of the fiberscope tip to obtain a 100% POGO score were evaluated as secondary outcomes. The time for FOI through i-gel Plus was significantly shorter than that through standard i-gel (median (IQR), i-gel Plus: 30.3 (25.4-39.0) s, vs standard i-gel: 54.7 (29.6-135.0) s; median of differences, 24.4 s; adjusted 95% confidence interval, 3.0-105.7; adjusted P = 0.040). Although the number of attempts for successful FOI was not significantly different, the VAS score for difficulty in the i-gel Plus group was significantly lower (easier) than that in the standard i-gel group. Moreover, i-gel Plus required a significantly smaller upward angle of the fiberscope tip to obtain a 100% POGO score. FOI can be performed more easily using i-gel Plus than using standard i-gel because of the improved fiberoptic visibility of vocal cords.

Continuous rectus sheath block in a patient with a postoperative rectus sheath hematoma: a case report.

BACKGROUND: Severe abdominal pain caused by a rectus sheath hematoma (RSH) can decrease a patient's activities of daily living. A case of postoperative RSH for which a continuous rectus sheath block (RSB) was effective is reported. CASE PRESENTATION: A 62-year-old woman who had no previous medical history underwent hysterectomy, total cystectomy, and ileal conduit surgery for bladder cancer under epidural and general anesthesia. She complained of severe abdominal pain 40 min after removal of the epidural catheter on postoperative day (POD) 4. Computed tomography showed an RSH on POD 12. For pain relief, an ultrasound-guided continuous RSB was performed on POD 17. After the block, the numerical rating scale (NRS) score during movement decreased immediately (from 10 to 2 or 3), and she had no further need for oral or intravenous analgesics. She was discharged from the hospital without any complications on POD 28. CONCLUSIONS: Continuous RSB can be an effective technique for pain relief of postoperative RSH.