Cannula Placement Research Articles

A minimally invasive, 3D-fluoroscopy-navigation-guided, 3D-controlled pedicle approach in spine surgery: first reliable results and impact on patient safety

PurposeSafe pedicle screw placement is a daily challenge to every spine surgeon. Introduction of minimally invasive approaches in spinal surgery led to an impaired facility of inspection of the surgical field increasing the importance of intraoperative imaging and navigation. During the past years, we established a minimally invasive, navigated approach in our clinical setting.MethodsWe retrospectively reviewed the accuracy of pedicle approaches in patients treated due to traumatic or osteoporotic fractures, spondylitis/discitis, and tumoral lesions. Guide wires for pedicle screws or kyphoplasty cannulas were inserted in a 3D-navigation-guided, minimally invasive technique. Positioning of the guide wires was verified via 3D-scan, and pedicle screws/kyphoplasty cannulas were then visualized via a.p./lateral radiographs. Accuracy data were compared to a standard navigated open approach control group with indications similar to the MIS-group.Results23 MIS patients were included in this study (25–84 years, mean 70 years) with a total of 154 placed guide wires. Handling of the navigated Jamshidi needle was easy and secure. The guide wires showed correct placement in 151/154 cases. Three wires (1.9%) needed correction of placement after control scan. There were no vascular or neurologic complications due to wire misplacement. In the open-surgery control group, 7/181 screws (3.9%) needed intraoperative correction presenting no significant difference compared to the correction rate of the MIS-group (p = 0.35).ConclusionOur study shows the feasibility and reliability of a navigation-guided, minimally invasive pedicle approach in the clinical setting. Therefore, reduced morbidity due to minimized approaches can be combined with higher accuracy of navigated pedicle screw/kyphoplasty cannula placement improving patient safety.

SUN-199 PHLEBOTOMY PRACTICE IN A TERTIARY CARE PEDIATRIC HOSPITAL - AUDIT FOR IMPLEMENTING "SAVE YOUR VEINS" INITIATIVE

Venipuncture is often done indiscriminately in hospitals leading to phlebitis and stenosis of veins. Patients with chronic diseases have difficult venous access and it is catastrophic in pediatric patients, more specifically those with chronic kidney diseases, hematological disease and cancers. Due to long life expectancy for paediatric chronic kidney patients, now all efforts must be focused on vein preservation for future use. Campaigns to preserve veins in kidney patients have been conducted worldwide, but not in developing countries. No paediatric specific data or campaigns are available. Hence, we reviewed the current practice of venipuncture in our pediatric department with special focus on nephrology patients. We aimed to assess the knowledge about vein preservation among our phlebotomists, nurses and junior doctors and review the current phlebotomy practice in pediatric patients in our center. A survey designed to test the knowledge among phlebotomists, nurses and junior doctors regarding vein preservation, assess current practice and willingness to get training was conducted and data was collected. Simultaneously we noted all venipunctures performed at the emergency department(ED), paediatric ward (PW) and paediatric outpatient department (OPD) in our hospital for 30 days. Data on admitting department, diagnosis, type of venipuncture (needle stick or cannula), purpose (sample collection or drug instillation), number of pricks and site preferred were collected. Outcomes like percentage of phlebotomies done by each group of health care personnel, preferred site and department or diagnosis associated with difficult venous access (2 or more attempts) were analysed. Out of 320 venipunctures recorded, 203 were considered for analysis (117 - insufficient data). The mean age of patients was 4.7 years. 85 (41.9%), 85(41.9%) and 33(16.2%) procedures were done in OPD, ED and PW respectively. General paediatrics department (n=116, 57.1%) had most patients, followed by nephrology (n= 34, 16.7%) and hematooncology (n= 33, 16.2%). 84/203 (41.3%) children were suffering from chronic disease. Nurses performed 103(50.7%), followed by phlebotomists (90 (44.3%)) and junior doctors (10(4.9%)). Only 17.2% requests had physician instruction regarding vascular access. 124 patients (61.1%) had needle stick and 79 patients (38.9%) had cannula placed. The preferred site used for needle stick method was cubital fossa (n=62, 50%) followed by dorsum of hand (n= 60, 48.3%). For cannula placement, 77/79 venipuncture attempts were made in dorsum of hand. 7% of patients required more than 1 attempt to obtain sufficient blood samples. Of 203 patients, 46 had difficult access and all these patients (100%) who had this difficult venous access were chronic disease patients (Kidney 50%, hematology 37.5%, endocrine 12.5% ). Only 60% of doctors and 33.3% of phlebotomists preferred dorsum of hand as first site. Vein preservation education is lacking and should be implemented in all hospitals. This strategy benefits children with chronic disease most, especially kidney disease. Interventions like flagging patients with chronic disease, use of wrist bands and bracelets, educating parents/children on vein preservation can help these patients.

Lumbar Radiofrequency Ablation: Procedural Technique.

Lumbar radiofrequency ablation is indicated for the treatment of chronic axial low back pain that is mediated by facet arthropathy which has failed more conservative treatment options. This article details proper equipment and medications, patient positioning and setup, step-by-step instructions for multiplanar fluoroscopic visualization, cannula placement, and postoperative management. Pearls and pitfalls are also discussed. In addition, an instructional procedure video (Supplemental Digital Content 1, http://links.lww.com/CLINSPINE/A90) accompanies this paper.

Zero-Fluoroscopy Ablation at the Texas Heart Institute.

Zero-Fluoroscopy Ablation at the Texas Heart Institute.

Transesophageal Echocardiography Compared to Fluoroscopy for Avalon Bicaval Dual-Lumen Cannula Positioning for Venovenous ECMO

The Avalon elite bicaval dual-lumen cannula for single site VenoVenous Extracorporeal Membrane Oxygenation (VV ECMO) offers several advantages. Correct placement of the Avalon cannula is safe using image guidance and needs either fluoroscopy or Transesophageal echocardiography (TEE). We assessed our institutional ECMO performance, cannulation related complications, instances of cannula malposition among patients cannulated using the two imaging modalities. We reviewed all patients who had Avalon cannula placement for VV ECMO at our institute. Ten patients were included in the study. Patients were cannulated using either fluoroscopy (Group A, n = 5) or TEE (Group B, n = 5). Data included patient demographics, diagnosis, evidence of cannula malposition, ECMO performance, cannulation related complications. The primary outcomes ease of cannulation; cannula malposition and the need for repositioning were compared between the two groups. Visualisation of guidewire, Avalon cannula and the average number of attempts to cannulate were similar (P > 0.05) between the two groups. Four patients cannulated using fluoroscopy had low flows whereas none of the patients cannulated using TEE had flow problems which was statistically significant (P = 0.024). Four cannulas (80%) placed under fluoroscopy required repositioning whereas one cannula (20%) placed under TEE needed repositioning. This difference was not statistically significant though (P = 0.099). TEE is the ideal imaging modality to guide Avalon elite cannula placement for VV ECMO.

SCIDOT-02. A PHASE I STUDY OF CONVECTION-ENHANCED DELIVERY OF LIPOSOMAL-IRINOTECAN (ONIVYDE) USING REAL-TIME IMAGING WITH GADOLINIUM IN PATIENTS WITH RECURRENT HIGH GRADE GLIOMAS: RESULTS THUS FAR

Abstract BACKGROUND Chemotherapy for high grade gliomas (HGG) is limited by the blood-brain-barrier (BBB). Convection enhanced delivery (CED) improves chemotherapy delivery by utilizing fluid convection obviating the challenges of crossing the BBB while minimizing systemic toxicity. CED of nanoliposomal-irinotecan (Onivyde) showed to be a superior delivery route for anti-tumor activity in animal models. An advance of this trial is the development and use of real time CED, which utilizes MRI to visualize the CED process with the aid of co-convected contrast agents, monitoring delivery into the brain and affording for corrective action. METHODS This is a 3 + 3 single dose escalation trial with 2 cohorts: 20mg/ml and 40mg/ml. Onivyde and GAD were co-infused via the same catheters in a one-time delivery. The total dose was personalized based on the patient’s tumor volume, and ranged from 20–680 mg of Onivyde, given via up to 4 catheters. Tumor diameters were allowed to be 1 – 4 cm, with injection volumes ranging from 2 – 17 mL of infusate. RESULTS 13 patients have been treated on this protocol, all in under 5 hours. There were 9 GBs, 1 gliosarcoma, 2 AAs, and 1 oligoastrocytoma. Utilizing imaging software, we correlated pre-infusion modeling of the drug distribution with post-infusion imaging. A number of technical challenges were overcome by real time monitoring; the total volume of distribution (Vd), and the Vd to volume infused (Vi) ratio for each infusion was ~2. Of all patients, the only notable AE was encephalopathy, which was resolved. CONCLUSIONS Image-guided distribution allows for safe real-time placement and adjustment of CED cannula of Onivyde into patient’s brains. Such methods allow for maximum tumor coverage and warrant further studies with repeat dosing.

Sensory mapping of lumbar facet joint pain: a feasibility study.

To evaluate the feasibility of sensory mapping of lumbar facet joint pain in patients scheduled to undergo radiofrequency (RF) denervation. Prospective cohort study. University teaching hospital. A total of 15 participants listed for RF denervation of lumbar facet joint. After written informed consent, participants were recruited to the study. Participants completed a pain diagram prior to their procedure. After successful image-guided placement of RF cannulas, the sensory detection threshold using 50 Hz stimulation was obtained, followed by application of suprathreshold stimulation. Participants mapped their stimulated area in comparison to their pre-procedure pain diagram. All 15 participants had previously undergone diagnostic blocks. All participants were able to report either pain or paraesthesia during suprathreshold stimulation. In total, 14 out of 15 participants reported complete coverage of their usual painful area with suprathreshold stimulation of nerves scheduled for RF denervation. In one of the participants, an area of upper lumbar pain was not covered during suprathreshold stimulation. Nearly two-thirds of the participants (n = 9), reported either pain or paraesthesia, outside their normal painful area during suprathreshold stimulation. A total of 71 nerves were scheduled for RF denervation. Sensory electrical stimulation was successfully achieved in 68 out of 71 nerves (96%). The average sensory detection threshold was found to be 0.3 V while the suprathreshold stimulation was 0.6 V. Lumbar facet joint pain can be mapped using suprathreshold sensory stimulation, which has the potential to introduce objectivity during RF denervation.

Posterior percutaneous endoscopic cervical foraminotomy and discectomy for degenerative cervical radiculopathy using intraoperative O-arm imaging.

IntroductionPosterior percutaneous endoscopic cervical foraminotomy and discectomy (P-PECD) is a minimally invasive technique for the treatment of degenerative cervical radiculopathy. The O-arm, an intraoperative mobile computed tomography (CT) scanner, may improve spine surgery outcomes.AimTo evaluate clinical outcomes of O-arm assisted P-PECD in patients with degenerative cervical radiculopathy.Material and methodsBetween January 2013 and January 2018, 32 patients with degenerative cervical radiculopathy who underwent P-PECD were followed up for 12 months. Their demographic, clinical and surgical data were reviewed retrospectively. All patients received intraoperative O-arm scanning to assess working cannula placement and decompression. The visual analogue scale (VAS), the neck disability index (NDI), and Odom’s criteria were used to evaluate clinical outcomes.ResultsCompared with preoperative values, mean NDI, neck-VAS, and arm-VAS scores were dramatically improved 1 week postoperatively, and the improvement was maintained for at least a year after surgery (from 27.6 ±10.5, 5.8 ±1.7, and 7.2 ±2.3 to 1.4 ±0.8, 1.1 ±0.8 and 0.9 ±0.6, respectively). According to Odom’s criteria, 27/32 patients (84.4%) reported excellent or good results. There were no permanent complications. One patient suffered from transient thumb weakness due to a cervical nerve root injury caused by the spinal needle.ConclusionsP-PECD aided by intraoperative O-arm imaging is a safe, effective, and minimally invasive procedure for treating degenerative cervical radiculopathy that can provide accurate cannula placement and thorough decompression.

Timing and Outcomes of an Indication-Only Use of Intravenous Cannulation During Spontaneous Labor.

In the United States, most women presenting in spontaneous labor undergo intravenous (IV) cannulation on admission to hospital labor and birth units. There is limited evidence for this routine practice in pregnant women at low risk for adverse outcomes during labor or birth. A retrospective, exploratory, descriptive study of an indication-only practice of IV cannulation on admission for women presenting in spontaneous labor and cared for by a nurse-midwife service was performed. Descriptive data included the timing of IV cannula placement (admission, during labor or postpartum period, or not at all) and indications for placement. Maternal outcomes of interest were estimated blood loss, postpartum hemorrhage rates, and management; neonatal outcome was 5-minute Apgar scores. Records for 1069 women cared for by nurse-midwives who presented in spontaneous labor were reviewed. In this cohort, 445 (41.6%) had IV access established on admission, 325 (30.4%) had an IV cannula placed during labor or postpartum, and 299 (28%) never had IV access during their hospital stay. For the 325 women with IV cannulas placed after admission, 25 (7.7%) were placed urgently for excessive postpartum bleeding. Further analysis of the subset of women who had a postpartum hemorrhage after vaginal birth (defined as >500 mL estimated blood loss) indicated that urgent IV cannulation was not associated with a lower mean postpartum hemoglobin or hematocrit or an increase in blood transfusion rate when compared with women who had an IV cannula placed earlier in their labor course. Indication-only IV cannulation for women experiencing an uncomplicated labor and birth is a reasonable practice in settings where IV access can be established urgently if needed.

GIANT CELL MYOCARDITIS: A SILENT BUT DEADLY KILLER

SESSION TITLE: Cardiovascular Cases SESSION TYPE: Med Student/Res Case Report PRESENTED ON: 10/22/2019 3:45 PM - 4:45 PM INTRODUCTION: Giant cell myocarditis (GCM) usually affects previously healthy adults and is a rapidly progressive and frequently fatal disease, accounting for approximately 17% of all myocarditis fatalities. Early diagnosis is critical, with evidence showing rapidly instituted cyclosporine-based immunosuppression can improve transplant-free survival. CASE PRESENTATION: A 56 year old male with a history of Type 2 Diabetes presented with 1 week of exertional dyspnea and lightheadedness. Initial exam and tests were remarkable for a mild Troponin leak. EKG revealed Left bundle branch block and transthoracic echocardiogram (TTE) showed a normal ejection fraction (EF) and Left Ventricular (LV) internal Dimension-Diastole of 5.4cm. Stress test, nuclear imaging and Left Heart Catheterization were normal. An event monitor documented exercise induced bradycardia leading to the placement of a dual chamber pacemaker. Repeat ECHO done at the time showed normal EF and a mild circumferential pericardial effusion. In the following two months the patient developed worsening exertional dyspnea (NYHA III). A CT angiogram revealed a large pericardial effusion with tamponade physiology. The aspirate showed 304 cells with 94% monocytes, protein of 4.4g/dl, and cytology revealed reactive mesothelial and chronic inflammatory cells. CRP was elevated. Repeat ECHO showed LV EF of 30% with akinesis of inferior and inferolateral wall as well as diffuse hypokinesis and severely increased RV size and RV thrombus. He was begun on anticoagulation. Subsequently, right heart catherization showed elevated RA pressures and cardiac MRI showed Biventricular dilation and nondiagnostic delayed gadolinium enhancement imaging. Endomyocardial biopsy from RV was not suggestive of GCM. Patient subsequently developed progressive cardiogenic shock requiring dual Ventricular Assist Device placement. On analysing excised core of LV apex for cannula placement, it revealed granulomatous myocarditis with Giant cell formation and pericarditis. He was started on milrinone, high dose steroids and anticoagulation for suspected GCM. An RVAD was placed. Eventually patient returned with fulminant septic shock and died. DISCUSSION: This case reveals the rapidly progressive nature of GCM,which from presentation, has a median survival of 3 months to death or transplant without appropriate therapy. Biopsy is diagnostic in >70% cases if done early, however false negatives are frequent due to the patchy nature of the disease CONCLUSIONS: With immunotherapy, the 5-year survival rate free of transplant is between 52-72%. Transplant is an effective strategy however GCM can recur in around 25% of transplanted hearts. Reference #1: Giant Cell Myocarditis: A Brief Review ; Arch Pathol Lab Med. 2016 Dec;140(12):1429-1434 : Xu J, Brooks EG Reference #2: Diagnosis, Treatment, and Outcome of Giant-Cell Myocarditis in the Era of Combined Immunosuppression;Riina Kandolin, Jukka Lehtonen, Kaisa Salmenkivi: DOI:10.1161/CIRCHEARTFAILURE.112.969261 Reference #3: Idiopathic Giant-Cell Myocarditis — Natural History and Treatment; Leslie T. Cooper, Jr., Gerald J. Berry : N Engl J Med 1997; 336:1860-1866 DISCLOSURES: No relevant relationships by Tanya Chandra, source=Web Response No relevant relationships by Abhas Khurana, source=Web Response No relevant relationships by Osama Mukarram, source=Web Response No relevant relationships by Anand Muthu Krishnan, source=Web Response No relevant relationships by Rudra Ramanathan, source=Web Response No relevant relationships by Nitya Sthalekar, source=Web Response

Feasibility of an ultrasound-guided approach to radiofrequency ablation of the superolateral, superomedial and inferomedial genicular nerves: a cadaveric study

IntroductionGenicular nerve radiofrequency (RF)denervation appears to be a promising treatment for knee pain in patients with degenerative osteoarthritis of the knee, when candidates are not suitable for arthroplasty. This study...

Pediatric Femoral Arterial Cannulations in Extracorporeal Membrane Oxygenation: A Review and Strategies for Optimization.

Venoarterial (VA) extracorporeal membrane oxygenation (ECMO) is a treatment strategy for pediatric patients with cardiopulmonary failure. Femoral cannulation is a commonly used technique for obtaining central access in children and adolescents despite high rates of vascular complications. Ischemic limb complications remain one of the most common problems facing survivors of femoral VA ECMO. Our aim is to review the literature on femoral cannulation in children and to present a review of techniques for femoral cannula placement, decannulation, and arterial repair to help minimize and ameliorate complications related to cannulation. We performed a literature review for pediatric ECMO cannulation, complications, and femoral artery repair in pediatric patients. We focused on the management of arterial and ischemia-related complications during and after ECMO support via femoral cannulation. Vascular complications are not infrequent for patients requiring ECMO support via femoral cannulation. As such, judicious distal perfusion monitoring as well as augmentation of distal flow are important strategies during mechanical support. The use of distal perfusion catheters can be used to minimize the risk of limb ischemia. As femoral cannulation grows more popular in pediatric patients, strategies for arterial repair are essential to ensure extremity perfusion upon decannulation.

In vitro evaluation of aerosol drug delivery with and without high flow nasal cannula in children.

To quantify aerosol delivery with or without a high flow nasal cannula (HFNC) in place using pressurized metered-dose inhaler (pMDI) and jet nebulizer (JN) with facemask in a simulated spontaneously breathing pediatric lung model. An upper airway model of a 9-month-old infant (Sophia Anatomical Infant Nose-Throat) with an absolute filter distal to the trachea was connected to a breathing simulator to simulate pediatric parameters (tidal volume = 100 mL, respiratory rate = 30 breaths/min, and I:E ratio = 1:1.4). Oxygen at 3 L/min was administered through an infant HFNC (Fisher & Paykel Healthcare Ltd, Auckland, New Zealand) attached to the nares of the model. Albuterol sulfate (2.5 mg/3 mL) was delivered with JN attached to an aerosol facemask and powered by air at 8 L/min. Ventolin Hydrofluoroalkane (HFA) (360 μg) was administered using pMDI connected to a valved holding chamber (VHC) with a facemask. Aerosol was administered to the model with and without HFNC in the nares (n = 3). Drug was eluted from the filter and quantified using spectrophotometry. Independent t tests were performed for data analysis (P < .05). Aerosol deposition was greater without HFNC (6.05% ± 1.53% and 39.54% ± 8.98% for JN and pMDI/VHC, respectively) than with HFNC using JN (2.91% ± 0.23%; P = .024) and pMDI/VHC (6.04% ± 0.28%; P = .003). Delivery efficiency of pMDI/VHC was greater than JN with or without nasal cannula in place (P = .0001 and .003, respectively). Aerosol administered via facemask over HFNC was less efficient than removing HFNC during administration. When delivering medical aerosol by facemask, the benefit of increased aerosol delivery must be weighed against the changes in oxygen delivery and risk of lung derecruitment when nasal prongs are removed.

Laparoscopic Cholecystectomy with Single Port Access System in 15 Dogs

To evaluate the outcome of laparoscopic cholecystectomy performed with a single port access system (SPAS) in dogs. Retrospective study. Fifteen client-owned dogs with nonobstructive gallbladder disease. Medical records were reviewed for signalment, clinical signs, diagnostic imaging, surgical findings, and outcome until suture removal. The SPAS was placed 1 cm caudal to the umbilicus. The procedure was completed with the SPAS alone in two cases. An additional cannula was added in 12 cases. In the last 10 cases, the additional cannula was placed at the beginning of the procedure. Dissection began at the cystic duct in 11 dogs (73%). In three cases (20%), the SPAS procedure was converted to a laparotomy; two of these conversions were elective, and one was emergent. The risk of conversion was affected by the experience of the surgeon (odds ratio = 0.53; P = .0105), and the rate of conversion was reduced when a cannula was added at the beginning of the procedure (P = .022). Fourteen dogs were discharged from the hospital. One dog died after being discharged due to severe cholangiohepatitis, and another dog died due to leakage of a gastrostomy tube. The use of SPAS for cholecystectomy in dogs has an acceptable outcome. The experience gained by the surgeon and the addition of a cannula reduced the risk of conversion. Laparoscopic cholecystectomy can be performed with a SPAS. The placement of an additional cannula at the beginning of the procedure is highly recommended.

Comparison of blood pressure measurements in the upper and lower extremities versus arterial blood pressure readings in children under general anesthesia.

PurposeTo compare invasive blood pressure (IBP) readings obtained from an arterial cannula with non-invasive blood pressure (NIBP) measurements from oscillometric cuffs on the upper and lower extremities of infants and children under general anesthesia.Patients and methodsPatients under 10 years of age were enrolled in our study if they were to receive general anesthesia with planned placement of a radial arterial cannula. At 5 mins intervals, IBP was measured using a fluid-coupled pressure transducer and NIBP was measured with two oscillometers with appropriately sized cuffs placed on the upper arm and lower leg, for 10 readings per patient.ResultsThe study enrolled 18 boys and 12 girls, ranging in age from 0 to 8 years. Across 300 data points, the absolute difference between the arm and invasive mean arterial pressure (MAP) measurements was 7±7 mmHg (range: 0–52 mmHg). The absolute difference between the leg and invasive MAP measurements was 8±8 mmHg (range: 0–52 mmHg). Although both non-invasive measurement sites demonstrated frequent deviation from invasive measurement, large deviations were more common when BP was measured at the leg (81 of 298 observations (27%) deviating by >10 mmHg) compared to the arm (60 of 300 observations (20%) deviating by >10 mmHg).ConclusionThe frequency of clinically significant NIBP deviation in children under general anesthesia supports the importance of IBP monitoring when hemodynamic fluctuations are likely and would be particularly detrimental. NIBP measured at the lower leg is more likely to result in clinically significant deviation from invasively measured MAP than NIBP values obtained from an upper arm.

Dynamic Needle Tip Positioning for Ultrasound-Guided Placement of a Peripherally Inserted Central Catheter in Pediatric Patients

Although a few studies have reported the efficacy of ultrasound-guided peripherally inserted central catheter placement for pediatric patients, the procedure still is challenging. Ultrasound-guided dynamic needle tip positioning technique is useful for vascular catheterization. There have been no reports on using dynamic needle tip positioning for peripherally inserted central catheter placement. The authors assessed the rate of successful peripherally inserted central catheter placement with dynamic needle tip positioning. Case series. Single tertiary institution. Forty patients <5 years old who were admitted to the pediatric intensive care unit after cardiac surgeries and required peripherally inserted central catheter placement. Peripherally inserted central catheter placement was performed under ultrasound guidance with dynamic needle tip positioning. The authors recorded the first attempt and overall success rates of peripherally inserted central catheter and outer cannula placement, time needed for outer cannula and peripherally inserted central catheter placement, and number of attempts. The first attempt and overall success rates of peripherally inserted central catheter placement were 85% (n = 34) and 97.5% (n = 39), respectively. The first attempt and overall success rates of outer cannula placement were 87.5% (n = 35) and 100% (n = 40), respectively. Time needed for outer cannula placement was 59.5 (interquartile range 40.5-80.5) seconds and for peripherally inserted central catheter placement was 112.5 (interquartile range 91.5-159.5) seconds. The number of attempts was 1 (interquartile range 1-1 [range 1-5]). In pediatric patients, ultrasound-guided peripherally inserted central catheter placement using dynamic needle tip positioning attained a high success rate.

Development of a novel frameless skull-mounted ball-joint guide array for use in image-guided neurosurgery.

Successful convection-enhanced delivery of therapeutic agents to subcortical brain structures requires accurate cannula placement. Stereotactic guiding devices have been developed to accurately target brain nuclei. However, technologies remain limited by a lack of MRI compatibility, or by devices' size, making them suboptimal for direct gene delivery to brain parenchyma. The goal of this study was to validate the accuracy of a novel frameless skull-mounted ball-joint guide array (BJGA) in targeting the nonhuman primate (NHP) brain. Fifteen MRI-guided cannula insertions were performed on 9 NHPs, each targeting the putamen. Optimal trajectories were planned on a standard MRI console using 3D multiplanar baseline images. After cannula insertion, the intended trajectory was compared to the final trajectory to assess deviation (euclidean error) of the cannula tip. The average cannula tip deviation was 1.18 ± 0.60 mm (mean ± SD) as measured by 2 independent reviewers. Topological analysis showed a superior, posterior, and rightward directional bias, and the intra- and interclass correlation coefficients were > 0.85, indicating valid and reliable intra- and interobserver evaluation. The data demonstrate that the BJGA can be used to reliably target subcortical brain structures by using MRI guidance, with accuracy comparable to current frameless stereotactic systems. The size and versatility of the BJGA, combined with a streamlined workflow, allows for its potential applicability to a variety of intracranial neurosurgical procedures, and for greater flexibility in executing MRI-guided experiments within the NHP brain.

Conversion Disorder Manifesting as Functional Visual Loss.

Children with conversion disorder experience neurological symptoms without a definable organic cause. Clinical presentation of conversion disorders is uncommon in the emergency department (ED). An 11-year-old previously healthy girl presented to the ED for management of lobar pneumonia. She developed acute visual loss subsequent to accidental placement of an intra-arterial cannula in her arm. Clinical assessments by the emergency physician, neurology, ophthalmology, and psychiatry services, and negative neuroimaging studies established the diagnosis of functional visual loss as a manifestation of conversion disorder. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: Conversion disorder symptoms are often without any specific markers and do not fit standard clinical guidelines. A comprehensive and step-wise evaluation of unusual clinical presentation by multiple specialties and ancillary test results should be considered to rule out organic causes and establish the diagnosis of conversion disorder, as seen in our patient.

Cannula position and Bernoulli effect contribute to leg malperfusion during extracorporeal life support with femoral arterial cannulation-an in silico simulation study†.

Limb ischaemia during extracorporeal life support (ECLS) using femoral artery cannulation is frequently observed even in patients with regular vessel diameters and without peripheral arterial occlusive disease. We investigated underlying pathomechanisms using a virtual fluid-mechanical simulation of the human circulation. A life-sized model of the human aorta and major vascular branches was virtualized using 3-dimensional segmentation software (Mimics, Materialise). Steady-state simulation of different grades of cardiac output (0-100%) was performed using Computational Fluid Dynamics (CFX, ANSYS). A straight cannula [virtualized 16 Fr (5.3 mm)] was inserted into the model via the left common femoral artery. The ECLS flow was varied between 1 and 5 l/min. The pressure boundary conditions at the arterial outlets were selected to demonstrate the downstream vascular system. Qualitative and quantitative analyses concerning flow velocity and direction were carried out in various regions of the model. During all simulated stages of reduced cardiac output and subsequently adapted ECLS support, retrograde blood flow originating from the ECLS cannula was observed from the cannulation site up to the aortic bifurcation. Analysis of pressure showed induction of zones of negative pressure close to the cannula tip, consistent with the Bernoulli principle. Depending on cannula position and ECLS flow rate, this resulted in negative flow from the ipsilateral superficial femoral artery or the contralateral internal iliac artery. The antegrade flow to the non-cannulated side was generally greater than that to the cannulated side. The cannula position and ECLS flow rate both influence lower limb perfusion during femoral ECLS. Therefore, efforts to optimize the cannula position and to avoid limb malperfusion, including placement of a distal perfusion cannula, should be undertaken in patients treated with ECLS.

Ultrasound-guided removal of cut intravenous cannula

The most common invasive intravascular procedure is the placement of the intravenous cannula. The use of peripheral venous cannulas may lead to a number of complications that may increase hospital stay, increase the cost of treatment, and decrease patient comfort. Spontaneous fracture and migration of intravenous cannula is a known complication and should be removed immediately. We report a case of a peripheral venous catheter (PVC) piece in the left cephalic vein treated successfully by a surgical approach. Our patient had to undergo intravenous cannulation for treatment of pneumonia and the cannula was cut on the second day by mistake during removal. The cut catheter piece was removed operatively. Inserting and removing a PVC is not always a simple and harmless procedure.