Oxygen delivery failure due to improper installation of carbon dioxide absorbent canister: a case report.

The CLIC system in the Dräger Apollo anesthesia workstation allows a successful pre-use machine checkout without the presence of a carbon dioxide absorbent canister. It also allows the canister to be changed without interrupting controlled ventilation. However, this canister can be easily installed improperly with the CLIC adapter. We report a case in which a patient could not be ventilated by mask after the induction of general anesthesia, resulting in oxygen desaturation before successful ventilation was achieved with a bag valve mask. This case illustrates the importance of a leak test after components of the breathing circuit are changed.

Paravertebral block: anatomy and relevant safety issues.

Paravertebral block, especially thoracic paravertebral block, is an effective regional anesthetic technique that can provide significant analgesia for numerous surgical procedures, including breast surgery, pulmonary surgery, and herniorrhaphy. The technique, although straightforward, is not devoid of potential adverse effects. Proper anatomic knowledge and adequate technique may help decrease the risk of these effects. In this brief discourse, we discuss the anatomy and technical aspects of paravertebral blocks and emphasize the importance of appropriate needle manipulation in order to minimize the risk of complications. We propose that, when using a landmark-based approach, limiting medial and lateral needle orientation and implementing caudal (rather than cephalad) needle redirection may provide an extra margin of safety when performing this technique. Likewise, recognizing a target that is not in close proximity to the neurovascular bundle when using ultrasound guidance may be beneficial.

Construction of an Affordable Lumbar Neuraxial Block Model Using 3D Printed Materials.

Access to affordable 3D printing technology has resulted in increased interest in the creation of medical phantom task trainers. Recent research has validated the use of these trainers in simulation education. However, task trainers remain expensive, limiting their availability to medical training programs. We describe the construction of a low-cost task trainer using fused filament fabrication (FFF) printed spinal vertebrae placed in a synthetic gelatin matrix. Additionally, our model contains a realistic simulated ligamentum flavum, a removable silicone skin, as well as spinal fluid reservoir that provides a positive endpoint for intrathecal blocks. The total cost of this model was less than $400 USD. The time to 3D print the bony anatomic parts was approximately 26 hours. While we have not formally validated our model, initial impressions of tactile feel and realism were deemed positive by experienced anesthesia providers. Future work will focus on continued refinement of the model features and construction.

Lumbar plexus block surface landmarks as assessed by computed axial tomography in adult patients with scoliosis: a case series.

BACKGROUND AND OBJECTIVES: Lumbar plexus (LP) block is a common and useful regional anesthesia technique. Surface landmarks used to identify the LP in patients with healthy spines have been previously described, with the distance from the spinous process (SP) to the skin overlying the LP being approximately two-thirds the distance from the SP to the posterior superior iliac spine (PSIS) (SP-LP:SP-PSIS ratio). In scoliotic patients, rotation of the central neuraxis may make these surface landmarks unreliable, possibly leading to an increased block failure rate and an increased incidence of complications. The objective of the present study was to describe these surface landmarks of the LP in patients with scoliosis. METHODS: We selected 47 patients with known thoracolumbar scoliotic disease from our institution's radiology archives. We measured bony landmark geometry, Cobb angle, and the LP location and depth. Additionally, we calculated the SP-LP:SP-PSIS ratio for both the concave and convex sides. RESULTS: In scoliotic patients (31 females and 16 males), the median (range) Cobb angle was 23 (8-54) degrees. The LP depth was 7.5 (5.7-10.7) cm on the concave side of the scoliotic spine and 7.6 (5.4-10.8) cm on the convex side, while the distance from the SP-LP was 3.4 (1.9-4.7) cm on the concave side and 3.7 (2.4-5.1) cm on the convex side. The SP-LP:SP-PSIS ratio was 0.61 (0.20-0.97) and 0.65 (0.45-0.98) on the concave and convex sides, respectively. None of these distances were significantly different between sides. CONCLUSIONS: In patients with scoliotic disease of the spine, there is wide variability in the bony surface landmarks. The location of the LP is generally more medial than expected when compared with both modified and traditional landmarks. A review of the imaging studies and the pre-procedural ultrasound assessment of the anatomy should be considered prior to needle puncture.

Effect of jaw thrust and cricoid pressure maneuvers on glottic visualization during GlideScope videolaryngoscopy.

PURPOSE: During performance of direct laryngoscopy in the difficult-to-visualize airway, several maneuvers have the potential to impact glottic visualization, including jaw thrust and cricoid pressure. The effect of these maneuvers on glottic visualization during videolaryngoscopy has not been studied. We evaluated the effect of jaw thrust and cricoid pressure maneuvers on both visualization of the glottis and the area of glottic opening visible during GlideScope-aided videolaryngoscopy. METHODS: One hundred patients were enrolled in this study. After induction of general anesthesia, videolaryngoscopy was followed by jaw thrust and cricoid pressure maneuvers performed in random order. Laryngeal anatomy was recorded continuously and was saved as digital images following the initial laryngoscopy and after each maneuver. Glottis grade [modified Cormack and Lehane (C&L)] was recorded, as was the total glottic area. RESULTS: There was improvement in glottis grade when utilizing jaw thrust maneuver in comparison to GlideScope videolaryngoscopy alone (31% improved, 4% worsened; P < 0.001). There was no difference in glottis grade when using the cricoid pressure maneuver in comparison with videolaryngoscopy alone (39% improved, 20% worsened; P = 0.19). Glottic opening area, however, was greater when utilizing the jaw thrust maneuver in comparison with videolaryngoscopy alone (P < 0.001), but smaller when utilizing the cricoid pressure maneuver in comparison with videolaryngoscopy alone (P < 0.001). CONCLUSIONS: The jaw thrust maneuver was superior to videolaryngoscopy alone in improving the modified C&L grade and the visualized glottic area; however, no significant improvement was noted with cricoid pressure. We therefore recommend the use of jaw thrust as a first-line maneuver to aid in glottic visualization and tracheal intubation during GlideScope videolaryngoscopy.

Real-time three-dimensional ultrasound for continuous interscalene brachial plexus blockade.

Two-dimensional ultrasound guidance is used commonly for regional anesthetic techniques. This report describes the novel use of three-dimensional, ultrasound-guided, continuous interscalene regional analgesia, which was used in a 36-year-old woman undergoing left total elbow arthroplasty. Possible advantages of this novel technology over current two-dimensional methods include a larger area of available scan information that enables multiple planes of view without having to reposition the ultrasound probe, and three-dimensional visualization of local anesthetic deposition perineurally. Current technological limitations include an upper frequency of 7 MHz, which decreases the resolution of superficial scanning.

Methylene blue-associated serotonin syndrome: a 'green' encephalopathy after parathyroidectomy.

INTRODUCTION: Methylene blue (MB) infusion is frequently used to localize the parathyroid glands during parathyroidectomy and generally considered safe. Several recent reports suggest neurological toxicity and post-operative altered mental state typically after large dose infusions. The mechanism by which MB has neurotoxic effects in some patients remains uncertain. CASE REPORT: A 67-year-old male underwent lumbar laminectomy followed by parathyroidectomy. Postoperatively, he was comatose (Glasgow Coma Scale of 7) and underwent extensive neurological evaluation. Brain computed tomography (CT) imaging and CT angiography revealed no ischemia, vessel occlusion, or hemorrhage. Electroencephalogram (EEG) showed only slowing of cerebral hemispheric activity bilaterally. Over the next 48 h, his mental status slowly improved and the patient made a full neurological recovery (Glasgow Coma Scale 15). CONCLUSION: Methylene blue, when used in patients on antidepressant drugs, may be associated with a transient encephalopathic state and serotonin syndrome. Patients on antidepressants undergoing parathyroidectomy who may receive MB infusion should be considered for alternative parathyroid gland identification or discontinuation of the antidepressants before surgery. MB-associated serotonin syndrome is an increasing and under recognized ('green') post-operative encephalopathy that warrants education to critical care neurologists and other physicians.

Real-time three-dimensional ultrasound-assisted axillary plexus block defines soft tissue planes.

Two-dimensional (2D) ultrasound is commonly used for regional block of the axillary brachial plexus. In this technical case report, we described a real-time three-dimensional (3D) ultrasound-guided axillary block. The difference between 2D and 3D ultrasound is similar to the difference between plain radiograph and computer tomography. Unlike 2D ultrasound that captures a planar image, 3D ultrasound technology acquires a 3D volume of information that enables multiple planes of view by manipulating the image without movement of the ultrasound probe. Observation of the brachial plexus in cross-section demonstrated distinct linear hyperechoic tissue structures (loose connective tissue) that initially inhibited the flow of the local anesthesia. After completion of the injection, we were able to visualize the influence of arterial pulsation on the spread of the local anesthesia. Possible advantages of this novel technology over current 2D methods are wider image volume and the capability to manipulate the planes of the image without moving the probe.