Is Ultrasound a Valid and Reliable Imaging Modality for Airway Evaluation?: An Observational Computed Tomographic Validation Study Using Submandibular Scanning of the Mouth and Oropharynx.

OBJECTIVES: Ultrasound (US) imaging of the airway may be useful in predicting difficulty of airway management (DAM); but its use is limited by lack of proof of its validity and reliability. We sought to validate US imaging of the airway by comparison to CT-scan, and to assess its inter- and intra-observer reliability. We used submandibular sonographic imaging of the mouth and oropharynx to examine how well the ratio of tongue thickness to oral cavity height correlates with the ratio of tongue volume to oral cavity volume, an established tomographic measure of DAM. METHODS: A cohort of 34 patients undergoing CT-scan was recruited. Study standardized assessments included CT-measured ratios of tongue volume to oropharyngeal cavity volume; tongue thickness to oral cavity height; and US-measured ratio of tongue thickness to oral cavity height. Two sonographers independently performed US imaging of the airway before and after CT-scan. RESULTS: Our findings indicate that the US-measured ratio of tongue thickness to oral cavity height highly correlates with the CT-measured ratio of tongue volume to oral cavity volume. US measurements also demonstrated strong inter- and intra-observer reliability. CONCLUSIONS: This study suggests that US is a valid and reliable tool for imaging the oral and oropharyngeal parts of the airway, as well as for measuring the volumetric relationship between the tongue and oral cavity, and may therefore be a useful predictor of DAM.

Point-of-care ultrasound defines gastric content and changes the anesthetic management of elective surgical patients who have not followed fasting instructions: a prospective case series.

PURPOSE: Pulmonary aspiration of gastric contents is a major cause of anesthesia morbidity and mortality. Point-of-care gastric ultrasound provides information regarding the type and volume of gastric content. The hypothesis of this prospective cohort study was that the addition of point-of-care gastric ultrasound to standard patient assessment results in changes in anesthetic management in at least 30% of elective surgical patients who do not follow fasting instructions. METHODS: Following Research Ethics Board approval and informed consent, elective surgical patients who did not follow fasting instructions were included in this prospective study. Documentation included the type of food ingested, the timing of the ingestion relative to the planned surgical time, and the treating anesthesiologist's management plan based on history alone. Next, an independent anesthesiologist not involved in the medical decision-making performed a focused gastric ultrasound examination. The results of the ultrasound exam were documented in a standardized fashion and made available to the attending anesthesiologist who then confirmed or revised the initial management plan. The treating anesthesiologist's actual (post-test) patient management was documented in a standardized fashion and compared with the initial (pre-test) management plan. RESULTS: Thirty-eight patients were included in this case series. Following point-of-care gastric ultrasound, there was a change in either the timing of anesthesia or the anesthetic technique (or both) in 27 patients (71%), with a net change towards a lower incidence of surgical delays. CONCLUSIONS: This prospective case series suggests that a standardized point-of care gastric ultrasound examination informs anesthesiologists' perceived level of aspiration risk and leads to changes in anesthetic management in a significant proportion of elective patients who did not follow fasting instructions.

The analgesic effects of proximal, distal, or no sciatic nerve block on posterior knee pain after total knee arthroplasty: a double-blind placebo-controlled randomized trial.

BACKGROUND: The analgesic efficacy of sciatic nerve block (SNB) after total knee arthroplasty (TKA) is unclear. Proximal and distal SNB are each reported to provide posterior knee analgesia, whereas others suggest that posterior knee pain is not important after TKA. This prospective, randomized, double-blind, parallel-arm, placebo-controlled trial examined whether proximal or distal SNB provides superior analgesia in the posterior knee compared with no SNB after TKA. METHODS: Sixty patients undergoing TKA were randomized to single-shot SNB using either the infragluteal (Proximal group) or popliteal (Distal group) technique, or no SNB (Placebo group). All patients received spinal anesthesia and continuous-femoral nerve blockade. A blinded observer assessed posterior and anterior knee pain at 2, 4, 6, 8, 12, and 24 h postoperatively. The primary outcome was moderate-to-severe posterior knee pain at 4 h postoperatively; secondary outcomes included SNB procedural time, needle passes, and discomfort. RESULTS: Fifty-three patients were analyzed. The proportion of patients (Proximal:Distal:Placebo) who experienced moderate-to-severe posterior knee pain was 18%:22%:89% (P<0.00001) at 2 h, 24%:28%:72% (P<0.01) at 4 h, and 12%:17%:78% (P=0.00003) at 6 h postoperatively. For the anterior knee, the proportion of patients reporting moderate-to-severe pain was 6%:11%:44% (P=0.02) at 2 h, 6%:6%:39% (P=0.012) at 4 h, and 12%:6%:44% (P=0.017) at 6 h postoperatively. Moderate-to-severe pain did not differ between groups beyond 6 h. Both proximal and distal SNB reduced rest pain in the posterior and anterior knee up to 8 h postoperatively compared with no SNB. The popliteal technique required shorter procedural time, fewer needle passes, and produced less discomfort. CONCLUSION: Proximal and distal SNB each reduce posterior and anterior knee pain after TKA compared with no SNB.

Primary undifferentiated high-grade pleomorphic cardiac sarcoma in the left atrium with atypical presentation.

A woman in her 60s had 4 months of malaise, fatigue, dyspnoea, night sweats and grade 3 clubbing. She had a pansystolic murmur and signs of congestive heart failure. Multimodal imaging with a transthoracic echocardiogram, transoesophageal echocardiogram and CT was carried out to diagnose and reconstruct the mass for surgical planning. A 2×2.8 cm circular dense mass was found in the left atrium with vegetations on the mitral valve. Positron emission tomography and cardiac MRI confirmed the mass's hypermetabolic activity and malignant features. Mitral valve replacement and surgical resection were performed. She was diagnosed with grade 3 undifferentiated cardiac sarcoma and referred to the sarcoma multidisciplinary team for further management given sarcoma's rarity and complexity. The poor prognosis of sarcoma was evident as her symptoms recurred 2 months postoperatively.

Post-medistinoscopy chylopericardium.

Isolated Chylopericardium (without chylothorax) is a rare clinical disorder that may happen idiopathically or secondary to trauma, radiotherapy, lymphatic anomalies, infections or mediastinal neoplasm. We present a case of middle-aged male with no past medical history of note prior to developing heavy sweating, loss of weight and cough. A series of investigations were done including chest computed tomography which showed enlarged mediastinal lymph nodes leading to uncomplicated mediastinoscopy and lymph node biopsy. Six days after being discharged, he developed dyspnoea and chest pain. Echocardiography revealed massive pericardial effusion. Pericardiocentesis was done and surprisingly revealed milky white chylous fluid. The patient was then successfully managed without the need for further intervention.

Ultrasound-guided brachial plexus block in a patient with multiple glomangiomatosis.

BACKGROUND AND OBJECTIVES: Glomangiomas are rare, vascular tumors consisting of an afferent artery, arteriovenous canal, neuro-reticular elements, collagen, and efferent veins, and are most often located in the soft tissue of the upper extremities. We describe how the use of ultrasound-guided nerve blockade altered the anesthetic management of a patient with multiple glomangiomatosis undergoing elective forearm surgery. ULTRASOUND FINDINGS: A 32-year-old man was scheduled for excision of painful glomangiomas from the ulnar aspect of his right wrist, with exploration of his ulnar nerve. The anesthetic concerns included (1) morbid obesity, (2) chronic pain syndrome and opioid intolerance, (3) a potentially difficult airway, and (4) obstructive sleep apnea. Ultrasound-guided supraclavicular blockade was the proposed anesthetic of choice. Ultrasound scan of the supraclavicular fossa revealed numerous vascular lesions surrounding the divisions of the brachial plexus. Color Doppler imaging confirmed these pulsatile lesions to be vascular in origin. Even under two-dimensional ultrasound guidance, we believed that the risk of vascular puncture and unintentional intravascular injection of local anesthetic was high, and therefore we abandoned the supraclavicular approach. A successful ultrasound-guided axillary brachial plexus blockade was performed uneventfully. CONCLUSIONS: Although multiple glomangiomatosis is a rare disease, this case illustrates the invaluable contribution that ultrasound has made to modern, regional anesthetic practice, especially for patients with aberrant anatomy in whom traditional nerve-localization techniques could result in serious complications.

Diagnosis of malignant pleural mesothelioma from pleural fluid by Fourier transform-infrared spectroscopy coupled with chemometrics.

This study was conducted to differentiate malignant pleural mesothelioma (MPM) from lung cancer (LC) and benign pleural effusion (BPE) from pleural fluids using the diagnostic power of Fourier transform-infrared spectroscopy with attenuated total reflectance mode coupled with chemometrics. Infrared spectra of MPM (n = 24), LC (n = 20), and BPE (n = 25) were collected, and hierarchical cluster analysis (HCA) and principal component analysis (PCA) were applied to their spectra. HCA results indicated that MPM was differentiated from LC with 100% sensitivity and 100% specificity and from BPE, with 100% sensitivity and 88% specificity, which were also confirmed by PCA score plots. PCA loading plots indicated that these separations originated mainly from lipids, proteins, and nucleic acids-related spectral bands. There was significantly higher lipid, protein, nucleic acid, and glucose contents in the MPM and LC. However, the significant changes in triglyceride and cholesterol ester content, protein and nucleic acid structure, a lower membrane fluidity, and higher membrane order were only observed in the MPM. To check the classification success of some test samples/each group, soft independent modeling of class analogies was performed and 96.2% overall classification success was obtained. This approach can provide a rapid and inexpensive methodology for the efficient differentiation of MPM from other pleural effusions.

An ultrasonographic and histological study of intraneural injection and electrical stimulation in pigs.

BACKGROUND: In this study we evaluated the minimum stimulating current associated with intraneural needle placement and sonographic appearance of intraneural injection. METHODS: We inserted a needle 2 cm inside 28 pig nerves (brachial plexus in vivo), recorded the minimum current to elicit a motor response, and injected dye (5 mL) under ultrasound (US) imaging. RESULTS: The minimum current to elicit a motor response was 0.43 mA (range: 0.12-1.8 mA). Nerve expansion was visualized by US in 24 of 28 nerves. Histology revealed penetration of the epineurium in these same 24 nerves. There was no evidence of dysplasia within the fascicle of any nerve. CONCLUSIONS: US may prove useful to detect intraneural injection, whereas a motor response above 0.5 mA may not exclude intraneural needle placement. The correlation between intraneural injection and neurological dysfunction remains unclear.

Ultrasound examination of peripheral nerves in the forearm.

BACKGROUND AND OBJECTIVES: We examined in a volunteer population whether nerves in the forearm could be seen consistently using ultrasound imaging and whether this new information could have implications for the way we perform regional anesthesia of the median, radial, and ulnar nerves. METHODS: Eleven volunteers underwent ultrasound examination of both forearms. The median, ulnar, and radial nerves were followed and images were obtained at the elbow, proximal forearm, mid forearm, distal forearm and wrist levels. In addition the radial nerve was followed proximally to a point 5 cm above the elbow. Images were compared for consistency of location of the nerves and depth from skin and width was calculated for each nerve at each level. RESULTS: Anatomy of each nerve was consistent except for one forearm where the median nerve was lateral to the brachial artery at the elbow and one forearm where a superficial ulnar artery only joined the ulnar nerve at the wrist. A convenient location for blockade of both median and ulnar nerves is the midforearm combining ease of visualization, ability to block all terminal branches and minimal potential for vascular injury. The radial nerve is seen most easily at the elbow although blockade of the superficial radial nerve may spare radial motor function. CONCLUSIONS: Nerves in the forearm are consistently located using ultrasound. Further confirmation in clinical practice is required.

Disclosure of risks associated with regional anesthesia: a survey of academic regional anesthesiologists.

BACKGROUND AND OBJECTIVES: In view of the relatively few large studies available to estimate the rates of complications following regional anesthesia, we aimed to identify and quantify the risks that academic regional anesthesiologists and regional anesthesia fellows disclose to their patients before performing central and peripheral nerve blockade. METHODS: We asked 23 North American regional anesthesia fellowship program directors to distribute a questionnaire to the regional anesthesiologists and regional anesthesia fellows at their institutions. The questionnaire was designed to capture the risks and corresponding incidences that are routinely disclosed to patients before performing the most common central and peripheral nerve block techniques. RESULTS: The total number of respondents was 79 from 12 different institutions. Fifty-eight (74%) respondents disclose risks of regional anesthesia in order to allow their patients to make an informed choice, whereas 20 (26%) disclose risks for medicolegal reasons. For central neural blockade, the most commonly disclosed risks are headache, local pain/discomfort, and infection. For peripheral nerve blockade, the most commonly disclosed risks are transient neuropathy, local pain/discomfort, and infection. For both central and peripheral nerve blockade, the risks most commonly disclosed are also those with the highest-reported incidences. CONCLUSIONS: The risks of regional anesthesia most commonly disclosed to patients by academic regional anesthesiologists and regional anesthesia fellows are benign in nature and occur frequently. Severe complications of regional anesthesia are far less commonly disclosed. The incidences of severe complications disclosed by academic regional anesthesiologists and their fellows can be inconsistent with those cited in the contemporary literature.

The sensitivity of motor response to nerve stimulation and paresthesia for nerve localization as evaluated by ultrasound.

BACKGROUND AND OBJECTIVE: Seeking paresthesia and obtaining a motor response to an electrical stimulus are the two most common methods of nerve localization for the performance of peripheral-nerve blocks. However, these two endpoints do not always correlate, and the actual sensitivity and specificity of either method remains unknown. The objective of this study is to determine the sensitivity of paresthesia and motor response to electrical nerve stimulation as tools for nerve localization when a 22-gauge insulated needle is used for the performance of axillary-nerve block. METHODS: After IRB approval and informed consent, 103 patients were enrolled. Real-time ultrasonography was used as the reference test. After needle-to-nerve contact was confirmed by ultrasonography, the patient was requested to report the presence of paresthesia, and a nerve stimulator was used to seek a motor response, with a stimulating current of 0.5 mA or less. RESULTS: One patient was excluded from analysis because of protocol violation. Paresthesia was found to be 38.2% sensitive and motor response was 74.5% sensitive for detection of needle-to-nerve contact. CONCLUSION: The very different and relatively low sensitivity of either technique may explain, in part, the lack of correlation previously reported between the 2 endpoints.

Structural effects of simvastatin on liver rat [corrected] tissue: Fourier transform infrared and Raman microspectroscopic studies.

Simvastatin is one of the most frequently prescribed statins because of its efficacy in the treatment of hypercholesterolemia, reducing cardiovascular risk and related mortality. Determination of its side effects on different tissues is mandatory to improve safe use of this drug. In the present study, the effects of simvastatin on molecular composition and structure of healthy rat livers were investigated by Fourier transform infrared and Raman imaging. Simvastatin-treated groups received 50 mg/kg/day simvastatin for 30 days. The ratio of the area and/or intensity of the bands assigned to lipids, proteins, and nucleic acids were calculated to get information about the drug-induced changes in tissues. Loss of unsaturation, accumulation of end products of lipid peroxidation, and alterations in lipid-to-protein ratio were observed in the treated group. Protein secondary structure studies revealed significant decrease in α-helix and increase in random coil, while native ß-sheet decreases and aggregated ß-sheet increases in treated group implying simvastatin-induced protein denaturation. Moreover, groups were successfully discriminated using principal component analysis. Consequently, high-dose simvastatin treatment induces hepatic lipid peroxidation and changes in molecular content and protein secondary structure, implying the risk of liver disorders in drug therapy.

Microscopic images dataset for automation of RBCs counting.

A method for Red Blood Corpuscles (RBCs) counting has been developed using RBCs light microscopic images and Matlab algorithm. The Dataset consists of Red Blood Corpuscles (RBCs) images and there RBCs segmented images. A detailed description using flow chart is given in order to show how to produce RBCs mask. The RBCs mask was used to count the number of RBCs in the blood smear image.

Infection related to ultrasound-guided single-injection peripheral nerve blockade: a decade of experience at toronto Western hospital.

The use of ultrasound guidance has revolutionized regional anesthesia practice. Ultrasound equipment disinfection techniques vary between institutions. To date, there are no large data set publications or evidence-based guidelines that describe risk-reduction techniques for infectious complications related to the use of ultrasound guidance for peripheral nerve blockade. We retrospectively reviewed the medical charts of 7476 patients who received ultrasound-guided single-injection peripheral nerve blockade from October 2003 to August 2013 using our institution's low-level disinfection technique in combination with a sterile transparent film barrier dressing to cover the ultrasound transducer. No indications of block-related infection were found. We conclude that using a practical and efficient low-level disinfection technique and sterile barrier dressing results in an extremely low rate of block-related infection following ultrasound-guided single-injection peripheral nerve blockade.

A valid and reliable assessment tool for remote simulation-based ultrasound-guided regional anesthesia.

BACKGROUND AND OBJECTIVES: The purpose of this study was to establish construct and concurrent validity and interrater reliability of an assessment tool for ultrasound-guided regional anesthesia (UGRA) performance on a high-fidelity simulation model. METHODS: Twenty participants were evaluated using a Checklist and Global Rating Scale designed for assessing any UGRA block. The participants performed an ultrasound-guided supraclavicular brachial plexus block on both a patient and a simulator. Evaluations were completed in-person by an expert and remotely by a blinded expert using video recordings. Using previous number of blocks performed as an indication of expertise, participants were divided into Novice (n = 8) and Experienced (n = 12) groups. Construct validity was assessed through the tool's reliable on-site and remote discrimination of Novice and Experienced anesthetists. Concurrent validity was established by comparisons of patient versus simulator scoring. Finally, interrater reliability was determined by comparing the scores of on-site and off-site evaluators. RESULTS: The Global Rating Scale was able to differentiate Novice from Experienced anesthetists both by on-site and remote assessment on a patient and simulation model. The Checklist was unable to discern the 2 groups on a simulation model remotely and was marginally significant with on-site scoring. CONCLUSIONS: This is the first study to demonstrate the validity and reliability of a Global Rating Scale assessment tool for use in UGRA simulation training. Although the checklist may require further refinement, the Global Rating Scale can be used for remote and on-site assessment of UGRA skills.

Ultrasound-guided sciatic nerve block in overweight and obese patients: a randomized comparison of performance time between the infragluteal and subgluteal space techniques.

BACKGROUND AND OBJECTIVES: Despite ultrasound (US) guidance, sciatic nerve block (SNB) remains among the least performed peripheral blocks. By targeting the tissue plane between the gluteus maximus and quadratus femoris muscles, the US-guided subgluteal space technique may facilitate the performance of US-guided SNB. We aimed to evaluate whether the subgluteal space technique shortens SNB performance time in overweight and obese patients compared with the conventional infragluteal technique. METHODS: Overweight and obese patients (body mass index, > 25 kg m ) undergoing US-guided SNB for knee arthroplasty received 30 mL admixture (1:2 lidocaine 2%; bupivacaine 0.5% with 1:200,000 epinephrine) in the tissue plane between the gluteus maximus and quadratus femoris (subgluteal space group) or around the sciatic nerve at the infragluteal level (infragluteal group). All patients received spinal anesthesia, continuous femoral nerve block, and postoperative multimodal analgesia. The primary outcome was SNB performance time defined as the time interval between placement of the US transducer on skin, and needle withdrawal after injection. Number of needle passes, procedural pain, SNB-related complications, SNB success, postoperative pain, and opioid consumption were also assessed. RESULTS: Twenty-seven patients were assessed (subgluteal space, 14; infragluteal, 13). Mean SNB performance time was 4.4 minutes (95% confidence interval, 3.7-5.0) for the subgluteal space group and 9.0 minutes (95% confidence interval, 7.7-10.3) for the infragluteal group (P < 0.0001). Number of needle passes and procedural pain scores were lower in the subgluteal space group. There were no differences in SNB success or analgesic outcomes. CONCLUSIONS: The subgluteal space technique may be performed 50% faster, with no detectable differences in block success and analgesic efficacy, compared with the infragluteal technique for US-guided SNB in overweight and obese patients receiving multimodal analgesia. Injection of local anesthetics along tissue planes may produce similar block characteristics to perineural injection for US-guided SNB.

Can ultrasound of the tibial nerve detect diabetic peripheral neuropathy? A cross-sectional study.

OBJECTIVE: Peripheral nerve imaging by portable ultrasound (US) may serve as a noninvasive and lower-cost alternative to nerve conduction studies (NCS) for diagnosis and staging of diabetic sensorimotor polyneuropathy (DSP). We aimed to examine the association between the size of the posterior tibial nerve (PTN) and the presence and severity of DSP. RESEARCH DESIGN AND METHODS: We performed a cross-sectional study of 98 consecutive diabetic patients classified by NCS as subjects with DSP or control subjects. Severity was determined using the Toronto Clinical Neuropathy Score. A masked expert sonographer measured the cross-sectional area (CSA) of the PTN at 1, 3, and 5 cm proximal to the medial malleolus. RESULTS: Fifty-five patients had DSP. The mean CSA of the PTN in DSP compared with control subjects at distances of 1 (23.03 vs. 17.72 mm(2); P = 0.004), 3 (22.59 vs. 17.69 mm(2); P < 0.0001), and 5 cm (22.05 vs. 17.25 mm(2); P = 0.0005) proximal to the medial malleolus was significantly larger. Although the area under the curve (AUC) for CSA measurements at all three anatomical levels was similar, the CSA measured at 3 cm above the medial malleolus had an optimal threshold value for identification of DSP (19.01 mm(2)) with a sensitivity of 0.69 and a specificity of 0.77 by AUC analysis. CONCLUSIONS: This large study of diabetic patients confirms that the CSA of the PTN is larger in patients with DSP than in control subjects, and US is a promising point-of-care screening tool for DSP.