Landmark Group Research Articles

Ultrasound-guided spinal anaesthesia in obstetrics: is there an advantage over the landmark technique in patients with easily palpable spines?

BackgroundData are scarce on the advantage of ultrasound-guided spinal anaesthesia in patients with easily identifiable bony landmarks. In this study, we compared the use of ultrasound to the landmark method in patients with no anticipated technical difficulty, presenting for caesarean delivery under spinal anaesthesia. MethodsA total of 150 pregnant women were recruited in this randomized, controlled study. Ultrasound examination and spinal anaesthesia were performed by three anaesthetists with experience in ultrasound-guided neuraxial block. Patients were randomized to either the Ultrasound Group (n=75) or the Landmark Group (n=75). In both groups the level of L3–4 or L4–5 was identified by ultrasound (transverse and longitudinal approach) or palpation. The primary outcome was the procedure time, measured from the time of skin puncture by the introducer to the time of viewing cerebrospinal fluid at the hub of the spinal needle. Secondary outcomes were the number of skin punctures, number of passes, and incidence of successful spinal blockade. ResultsThe average procedure time, number of skin punctures and needle passes, were similar in both groups. The number of patients with successful spinal anaesthesia after one puncture was not statistically different between the groups. ConclusionThe present results indicate that when performed by anaesthetists experienced in both ultrasound and landmark techniques, the use of ultrasound does not appear to increase the success rate of spinal anaesthesia, or reduce the procedure time or number of attempts in obstetric patients with easily palpable spines.

The influence of the direction of J-tip on the placement of a subclavian catheter: real time ultrasound-guided cannulation versus landmark method, a randomized controlled trial

BackgroundIt has been reported that the direction of the guidewire J-tip is associated with misplacement of a central venous catheter. We hypothesized that real-time ultrasound-guided infraclavicular subclavian venous cannulation would be less influenced by the direction of guidewire J-tip compared to landmark method.MethodsSixty adult patients who required subclavian venous catheterization for neurosurgery were enrolled in this prospective randomized controlled study. Patients were randomly divided into a landmark group (n = 30) or an ultrasound group (n = 30). After the subclavian vein was punctured, the guidewire was advanced with the guidewire J-tip directed cephalad. Misplacement or advancement failure of the guidewire was regarded as an unsuccessful placement. Postoperative chest radiography was performed to confirm pneumothorax and the location of the catheter tip.ResultsThe two groups were comparable with respect to age, gender, height, and weight distribution. The incidence of unsuccessful guidewire placement was lower in the ultrasound group than in the landmark group (13% vs. 47%, P = 0.01). Among the unsuccessful guidewire placements, the incidence of misplacement were comparable between the groups and were all located in the ipsilateral internal jugular vein (7% vs. 7%). However, the incidence of advancement failure was significantly higher in landmark group (40% vs. 7%, P = 0.005). There were no complications such as pneumothorax or hemothorax.ConclusionsThe proper placement of guidewire was less influenced by the direction of the guidewire J-tip with ultrasound-guided subclavian venous cannulation than with the landmark approach.

Is Ultrasound-guided Central Venous Port Placement Effective to Avoid Pinch-off Syndrome?

Ultrasound (US)-guided internal jugular vein access has been the standard practice of central venous port (CVP) placement. The subclavian vein (SCV) access has also been preferred, but has potential risk of pinch-off syndrome (POS). The purpose of this study was to examine the effect of US-guided SCV access to avoid POS in patients with CVP. Included in this study were patients who had undergone CVP placement via the SCV. We mainly assessed the computed tomography (CT) findings from two different placement techniques of a CVP via the SCV: (i) venipuncture point described by the ratio between the distance from the venipuncture point to the sternoclavicular joint and the clavicular length; and (ii) presence of direct attachment of the catheter to the clavicle. Secondary outcome was POS rate associated with two different placement techniques of CVP via the SCV. A total of 237 patients were included in this study between August 2007 and January 2011. A total of 100 patients (42.2%) underwent CVP placement using the landmark technique while 137 patients (57.8%) underwent CVP placement by US guidance. CT revealed that the US-guided technique tended to be lateral SCV approach compared with the landmark technique (p<0.001). A total of four patients (1.7%) experienced POS, all of them in the landmark group. Our results showed that the US-guided technique determines a more lateral SCV approach, with a reduced POS risk than the landmark venipuncture technique.

Ultrasound Guided Port-A-Cath Implantation

Purpose: The use of port catheters is well accepted in the management of patients with malignancy. In this study, we compare the technical success and the complication rates of ultrasound guided Port-A-Cath implantation with doing this procedure by using the anatomical landmark method. Methods: In a retrospective study, from 2006 to 2009, medical files of 104 patients who had undergone Port-A-Cath implantation were reviewed. The indication for port catheter implantation was malignancy in all cases. Among our patients, Port-A-Cath implantation was done in 63 patients by using landmark method and in 41 patients by guidance of ultrasound. All patients had been observed for complications including pain, port infection, and port thrombus, thrombus of central veins, skin necrosis, and success in using of Port-A-Cath for at least one month following the procedure, in the vascular clinic. Results: in landmark method group, 2 catheters were non-functional just after placement (3.2%) while all Port-A-Caths in ultrasound-guided group were functional. Ten patients (15.9%) in land mark group and 1 patient (2.4%) in ultrasound-guided group were complicated. The difference between complication rate in anatomic landmarks method and ultrasound-guided method was statistically significant (p There was no significant difference in two groups in duration of port placement (p

Efficacy of ultrasound-guided combined C5 and superficial cervical plexus block in patients undergoing clavicle surgery

Objective To evaluate the efficacy of ultrasound-guided combined C5 and superficial cervical plexus block in patients undergoing clavicle surgery.Methods Sixty ASA physical status Ⅰ or Ⅱ patients,scheduled for elective clavicle surgery,were randomly divided into 2 groups (n =30 each) using a random number table:injection with 10 ml local anesthetic guided by ultrasound group (group U),and injection with 10 ml local anesthetic guided by anatomical landmark group (group A).A mixture of 0.375 ％ levobupivacaine and 1.0％ lidocaine was used.The time spent performing the block onset time of analgesia,onset time of analgesia in the medial border,midpoint and lateral border of the clavicle and duration of analgesia were measured.The effectiveness of block (excellent,good,failure) was assessed.The complications were observed.Results Compared with group A,the time spent performing the block was significantly prolonged,the onset time of analgesia in the lateral border and midpoint of the clavicle was shortened,the rate of excellent anesthesia was increased,and the duration of analgesia was prolonged in group U (P ＜ 0.05).No complications occurred in group U,while vascular puncture occurred in 3 cases,and one patient developed mild toxic reaction in group A.Conclusion Ultrasound-guided combined C5 and superficial cervical plexus block provides better block,with faster onset time of analgesia in the lateral border and midpoint of the clavicle,longer duration of analgesia and fewer complications as compared with that guided by anatomical landmarks in patients undergoing clavicle surgery. Key words: Ultrasonography ; Clavicle ; Brachial plexus ; Cervical plexus ; Nerve block

Stem Cell Transplant Versus Chemotherapy in Older Adults with Acute Myelogenous Leukemia In First Remission

▪ IntroductionOptimal therapy for older adults with acute myelogenous leukemia (AML) who achieve remission following induction chemotherapy has not been determined. Options include consolidation chemotherapy (CC) or stem cell transplant (SCT) if an appropriate donor is identified. In order to determine whether SCT improved overall survival (OS) or whether associated toxicity was increased, we performed a retrospective study comparing SCT with CC in this older age group. MethodsAll adult patients ages 60 to 75 years with AML in 1st remission (CR1) who underwent a SCT at MSKCC between 2001 and 2013 were reviewed and compared to age-matched patients with AML who achieved CR1 and received CC. A landmark analysis at 3 months following CR1 was used to compare OS for the 2 patient groups. Only SCT patients transplanted by landmark time were included in the analysis. Overall survival was compared using Kaplan-Meier methodology. ResultsSixty-eight patients were identified for the SCT group. Thirty-two patients were identified for the CC group (Table). Stem cell sources included: peripheral blood (n=63), cord blood (n=4) and bone marrow (n=1). Fifty-six patients received a T cell depleted transplant (32 with ClinMACsTM and 24 with IsolexTM ) and 12 received an unmodified product. Conditioning regimens were busulfan/melphalan/ fludarabine (n=54), melphalan/fludarabine (n=4), cyclophosphamide/fludarabine/thiotepa/ TBI (n=4), fludarabine/busulfan (n=3), busulfan/melphalan (n=2) and thiotepa/fludarabine/TBI (n=1). Donors included matched unrelated (n=28), matched related (n=25), mismatched unrelated (n=11) and mismatched cord blood (n=4). For patients in the CC group, induction chemotherapy included cytarabine in combination with either idarubicin (n=21), daunorubicin (n=10), or mitoxantrone plus etoposide (n=1). Forty-four patients received their transplant by the 3 month landmark and 30 patients in the CC group were alive at the landmark and were included in the OS analysis.Patient Characteristics:SCTCCNumber of patients6832Median age at SCT or CC65 (60-75)65 (60-69)Males/Females41/2718/14Median F/U in mos (range)19 (1-83)22 (11-75)Number of deaths within 100 days of SCT or 1st cycle CC6 (9%)2 (6%) [Display omitted] Deaths in the SCT group included 4 patients from infection, 1 from treatment-related toxicity, and 1 from relapsed disease. The estimated OS at 2 years in the landmark groups were 64% in the SCT group and 42% in the CC group (p=0.04). ConclusionsRecognizing the inherent bias when retrospective studies compare SCT and CC, these data support the use of SCT for older patients with AML in CR1 who have an appropriate donor. Despite the older age, there was a statistically significant better OS with low 100 day mortality for those patients who underwent SCT. Disclosures:No relevant conflicts of interest to declare.

Ultrasound-guided intrathecal anesthesia: Does scanning help?

Intrathecal anesthesia is widely used for many surgical procedures. Multiple attempts at needle placement may cause various complications and patient dissatisfaction.AimTo use a preprocedure ultrasound-guided surface marking, using a midline transverse interlaminar ultrasound view at L4–5 interspace, to guide needle insertion, aiming to decrease needle attempts.Subjects and methodsNinety patients ASA I–II, scheduled for intrathecal anesthesia, were included in the study. Patients were randomly allocated to one of 2 groups. Group I was the ultrasound group and Group II was the surface landmark group. For each block, we recorded patient’s and spine characteristics, number of needle attempts, and patient satisfaction, time for establishing landmarks by preprocedure ultrasound scanning or palpation, time to perform spinal anesthesia, and total time to perform the whole procedure.ResultsSuccessful first needle attempt was in (80%) in ultrasound group (I) and 17 (37.8%) in surface landmark group (II). Needle redirection attempts were 7 (15.6%) in group I and 16 (35.5%) in group II. Second attempt was in 2 (4.4%) in group I and 5 (11.1%) in group II. Third attempt was observed only in group II in 7 (15.6%). There was a significantly more time needed to establish landmarks and complete spinal anesthesia in group I compared to group II (8.7 ± 1.0 vs 5.4 ± 0.4, respectively). Patient’s satisfaction was significantly higher in group I (95.6%) than group II (77.8%).ConclusionPreprocedure ultrasound scanning improved the first needle attempt success rate, decreased redirection or further attempts, and gave better patient satisfaction.

Ultrasound-guided central venous cannulation is superior to quick-look ultrasound and landmark methods among inexperienced operators: a prospective randomized study

Quick-look ultrasound with a skin mark (UM) has been frequently used for central vein cannulation. The aim of this study is to compare this method with landmark (LM) and ultrasound-guided (UG) cannulation of jugular and femoral veins by inexperienced operators. Prospective randomized single-center study. A medical intensive care unit (ICU) of a university medical center. Patients requiring jugular or femoral central cannula placement. Each inexperienced resident randomly inserted a central venous line using the UM, LM or UG technique. The primary outcome was the success rate, and secondary outcomes were the placement time, number of attempts, mechanical complication rate, and catheter colonization rate. A total of 118 patients were randomly assigned to the three groups. The mean age of patients included in the study was 65±15years, and the mean Simplified Acute Physiology Score2 (SAPS2) was 57±20. The success rate was higher in the UG group than in the LM and UM groups (100, 74, and 73%, respectively; p=0.01). The total number of mechanical complications was higher in the LM and UM groups than in the UG group (24 and 36 versus 0%, respectively; p=0.01). The number of attempts and the access time were higher in the LM group than in the UG group, but not compared with the UM group. No difference in terms of catheter colonization was observed between the three groups. Ultrasound-guided cannulation of the internal jugular or femoral vein by inexperienced residents appears to be more reliable than the LM or UM methods and was associated with a lower mechanical complication rate among ICU patients.

Optimal 3-D Landmark Placement for Vehicle Localization Using Heterogeneous Sensors

Optimal placement of sensors or landmarks for the localization of an autonomous guided vehicle (AGV) based on range measurements is considered. The optimization relies on the Fisher information matrix (FIM). A closed-form expression of the FIM determinant is obtained for 2-D and 3-D spaces, considering heterogeneous sensors and distance-dependent ranging errors. Analytical bounds on the FIM determinant are derived, and several optimal landmark placement expressions for specific scenarios using two groups of landmarks are given. A minimax formulation for the optimal landmark placement is proposed and iteratively solved using exponential smoothing. There are several key features integrated into the proposed approach. These include 1) averaging of the cost function over elementary regions of the AGV search space to include the effect of the whole search space, 2) using a projected gradient search to stay within the boundaries of the landmark search space, and 3) searching on a convex space for placing the landmarks. Convergence issues of the proposed algorithm are discussed. Numerical results demonstrate that the proposed optimal landmark placement enables accurate AGV localization over significantly large volume or area of the search space compared with the case when landmarks are randomly placed.

A Prospective Randomized Trial of Ultrasound- vs Landmark-Guided Central Venous Access in the Pediatric Population

The purpose of this prospective randomized study was to compare landmark- to ultrasound-guided central venous access when performed by pediatric surgeons. The American College of Surgeons advocates for use of ultrasound in central venous catheter placement; however, this is not universally embraced by pediatric surgeons. Complication risk correlates positively with number of venous cannulation attempts. With IRB approval, a randomized prospective study of children under 18 years of age undergoing tunneled central venous catheter placement was performed. Patient accrual was based on power analysis. Exclusion criteria included known nonpatency of a central vein or coagulopathy. After randomization, the patients were assigned to either ultrasound-guided internal jugular vein access or landmark-guided subclavian/internal jugular vein access. The primary outcomes measure was number of attempts at venous cannulation. Secondary outcomes measures included: access times, number of arterial punctures, and other complications. Continuous variables were compared using 2-tailed Student's t-test. Discrete variables were analyzed with chi-square. Significance was defined as p < 0.05. There were 150 patients enrolled between April 2008 and September 2011. There was no difference when comparing demographic data. Success at first attempt was achieved in 65% of patients in the ultrasound group vs 45% in the landmark group (p = 0.021). Success within 3 attempts was achieved in 95% of ultrasound group vs 74% of landmark group (p = 0.0001). Ultrasound reduced the number of cannulation attempts necessary for venous access. This indicates a potential to reduce complications when ultrasound is used by pediatric surgeons.

Landmarks in nature to support wayfinding: the effects of seasons and experimental methods

Landmarks constitute an essential basis for a structural understanding of the spatial environment. Therefore, they are crucial factors in external spatial representations such as maps and verbal route descriptions, which are used to support wayfinding. However, selecting landmarks for these representations is a difficult task, for which an understanding of how people perceive and remember landmarks in the environment is needed. We investigated the ways in which people perceive and remember landmarks in nature using the thinking aloud and sketch map methods during both the summer and the winter seasons. We examined the differences between methods to identify those landmarks that should be selected for external spatial representations, such as maps or route descriptions, in varying conditions. We found differences in the use of landmarks both in terms of the methods and also between the different seasons. In particular, the participants used passage and tree-related landmarks at significantly different frequencies with the thinking aloud and sketch map methods. The results are likely to reflect the different roles of the landmark groups when using the two methods, but also the differences in counting landmarks when using both methods. Seasonal differences in the use of landmarks occurred only with the thinking aloud method. Sketch maps were drawn similarly in summertime and wintertime; the participants remembered and selected landmarks similarly independent of the differences in their perceptions of the environment due to the season. The achieved results may guide the planning of external spatial representations within the context of wayfinding as well as when planning further experimental studies.

Ultrasound-guided internal jugular vein access: Comparison between short axis and long axis techniques

The use of real-time ultrasound (US) is advantageous in the insertion of central venous catheters (CVCs) in adults, especially in whom difficulties are anticipated for various reasons. The aim of the present study was to compare two different real-time 2-dimensional US-guided techniques [short axis view/out-of-plane approach (SAX OOP approach) versus long axis view/in-plane approach (LAX IP approach)] for internal jugular vein (IJV) cannulation. In this prospective study, 90 critical care and hemodialysis patients were assigned for insertion of CVCs using either the real-time US-guided (SAX OOP approach or LAX IP approach) or landmark technique (control group). Failed catheter placement, risk of complications from placement, failure on first attempt at placement, number of attempts until successful catheterization, time to successful catheterization, incidence of central line-associated blood stream infection (CLA-BSI) and demographics of each patient were recorded. There were no significant differences in patient's demographic characteristics, side of cannulation (right or left) or presence of risk factors for difficult venous cannulation between the three groups of patients. Cannulation of the IJV was achieved in all patients by using US (SAX OOP and LAX IP approaches) and in 27 of the patients (90%) by using the landmark technique (P = 0.045). Average access time (skin to vein) and number of attempts were comparable between the SAX OOP and the LAX IP approaches while significantly reduced in both US groups of patients compared with the landmark group (P <0.001). In the landmark group, puncture of the carotid artery occurred in 16.7% of the patients, hematoma in 23.3% of the patients, pneumothorax in 3.3% of the patients and CLA-BSI in 20% of the patients, which were all significantly increased compared with the US group (P <0.05). The findings of this study suggest that the SAX OOP and LAX IP approaches were comparable for cannulation of IJV in critical care and hemodialysis patients. Furthermore, both US-guided techniques were superior to the landmark technique for insertion of CVCs.

Internal jugular vein cannulation: A comparison of three techniques

Context:Ultrasound-guided internal jugular vein (IJV) cannulation is known for increasing success rate and decreasing rate of complications. The ultrasound image can be used as a real time image during cannulation or to prelocate the IJV before attempting cannulation.Aims:This study compares both the ultrasound-guided technique with the classical anatomical landmark technique (central approach) for right IJV cannulation in terms of success rate, complications, and time for cannulation.Settings and Design:A prospective, randomized, observational study was conducted at a tertiary care hospital.Material and Methods:One hundred twenty patients requiring IJV cannulation were included in this study and were randomly allocated in three groups. Number of attempts, success rate, venous access time, catheterization time, and complications were observed in each group.Statistical Analysis Used:Statistical analysis was performed using STATA-9 software. Demographic data were compared using one-way analysis of variance (ANOVA). Nonparametric data were compared using the Kruskall–Wallis test, and multiple comparisons were done applying The Mann–Whitney test for individual pairs of groups. Nominal data were compared by applying the Chi-square test and Fisher exact test.Results:Successful cannulation (≤3 attempt) was achieved in 90.83% of patients without any statistical significant difference between the groups. Venous access time and catheterization time was found to be significantly less in both the ultrasound groups than the anatomical land mark group. Number of attempts and success in first attempt was similar between the groups.Conclusions:Both the ultrasound techniques are found to be better than the anatomical landmark technique. Further, ultrasound-guided prelocation was found to be as effective as ultrasound guided real-time imaging technique for right IJV cannulation.

Benefit of Long-Term Dual Anti-Platelet Therapy in Patients Treated With Drug-Eluting Stents: From the NHLBI Dynamic Registry

The optimal duration of dual-antiplatelet therapy (DAPT) after drug-eluting stent (DES) implantation is an important, unanswered question. This study was designed to evaluate the association of varying durations of DAPT on clinical outcomes after DES implantation for the treatment of coronary artery disease. Using the National Heart, Lung, and Blood Institute Dynamic Registry, patients enrolled in the last 2 waves after index percutaneous coronary intervention with DES and who were event free at the time of landmark analysis were included. Landmark analysis was performed 12 and 24 months after percutaneous coronary intervention, and patients were stratified according to continued use of DAPT or not. Subjects were evaluated for rates of death, myocardial infarction, and stent thrombosis at 4 years from their index procedures. The numbers of evaluable patients were 2,157 and 1,918 for the 12- and 24-month landmarks, respectively. In both landmark analyses, there was a significantly lower 4-year rate of death or myocardial infarction in the group that continued DAPT compared to the group that did not (12 months: 10.5% vs 14.5%, p=0.01; 24 months: 5.7% vs 8.6%, p= 0.02). Beneficial differences in the group that continued on DAPT were preserved after multivariate and propensity adjustment. There were no significant differences in definite stent thrombosis in either landmark analysis. In conclusion, at 12 and 24 months after DES implantation, continued use of DAPT was associated with lower 4-year risk for death and myocardial infarction.

Ultrasound-guided femoral vein catheterization in neonates with cardiac disease*

To describe a novel technique for real-time, ultrasound-guided femoral vein catheterization in neonates with cardiac disease, and to compare it to a contemporaneous cohort of neonates undergoing femoral vein central venous line placement via landmark technique. Retrospective cohort study of data extracted from a quality improvement database. Pediatric cardiac intensive care unit and cardiovascular operating room in pediatric tertiary hospital. One hundred fifteen neonates (mean weight, 3.07 ± 0.41 kg) with cardiac disease who underwent femoral central venous line attempts from January 2009 to September 2011. Study populations were similar in age, weight, and Risk Adjustment for Congenital Heart Surgery-1 category, but differed in intubation status (32% vs. 100%, ultrasound vs. landmark, p < .0001). Central venous line success rate was superior in the ultrasound group: 72 of the 76 (94.7%) vs. 31 of the 39 (79.5%), p = .02. Ultrasound group also had a superior first (75% vs. 30.8 %) and second attempt success rate (90.8% vs. 51.3%), p value for both < .0001. Inadvertent arterial puncture occurred less frequently in the ultrasound group: four of the 76 (5.3%) vs. nine of the 39 (23.1%), p = .01. There was a trend toward more venous thrombosis in the landmark group, 16 of the 39 (41%) vs. 18 of the 76 (23.7%), p = .08. Among all 115 subjects, there was a very strong association between greater than two central venous line attempts and the odds of being diagnosed with a deep venous thrombosis (odds ratio, 9.3; 95% confidence interval 3.5-24.8) and the odds of suffering an inadvertent femoral arterial puncture during the central venous line event (odds ratio, 8.8; 95% confidence interval 10.6-730). This novel long-axis real-time ultrasound technique facilitates placement of femoral vein central venous line in critically ill neonates with cardiac disease at a higher rate of success with fewer attempts and lower occurrence of complications when compared with the landmark technique.

Anatomy of the petrous apex as related to the endoscopic endonasal approach

The endoscopic endonasal approach (EEA) has been reported to be an efficient approach for treating lesions of the petrous apex. However, there have been only limited anatomic studies for the EEA. Furthermore, most of the relevant distances for EEA cannot be measured easily on a cadaveric skull. Two fresh adult cadaver heads and five formalin-fixed adult cadaver heads were dissected using the EEA to identify groups of landmarks for safe guidance during this approach. The distances between these landmarks were then measured by CT angiography by using three-dimensional software. The EEA to the petrous apex can be divided into five phases. In each phase, a group of landmarks, rather than a single landmark, can be identified easily for guiding the next phase of the approach. There was no significant difference between males and females in any of the distances reported in the present study. The EEA can be performed to manage a petrous apex lesion more safely by referring to multiple landmarks and the distances between them.

Ultrasound-guided infraclavicular axillary vein puncture is effective to avoid pinch-off syndrome: a long-term follow-up study

Pinch-off syndrome (POS) is a serious complication encountered during the long-term management of totally implantable access ports (TIAPs). The aim of this study was to examine the effect of ultrasound-guided infraclavicular axillary vein puncture to avoid POS in patients with long-term use of a TIAP. This was a retrospective review of 207 consecutive TIAPs: one hundred devices implanted using an anatomical landmark technique were used as historical controls (Landmark group), while 107 devices were implanted using an ultrasound (US)-guided puncture method (US group). The pinch-off grade (POG) was determined using chest X-ray findings following the definition of Hinke, and the progression of POG during the follow-up period of the Landmark and US groups was compared. Sixteen cases in the Landmark group were POG-1 and 3 were POG-2, while all cases in the US group were POG-0 at the time of venipuncture (p < 0.001). Eleven patients in the Landmark group showed some degree of progression of the POG during the follow-up period. In contrast, there were no cases showing progression of the POG in the US group (p = 0.002). US-guided infraclavicular axillary vein puncture was found to effectively make it possible to avoid POS for the long-term management of TIAPs, as well as at the time of implantation.

Changes in attention to relevant and irrelevant stimuli during spatial learning.

Rats were trained in 2 experiments to find a submerged platform that was situated in 1 of 2 of the 4 corners of a rectangular pool with a curved long wall. Different landmarks occupied 2 of the corners on every trial, and the platform was always situated near a landmark. For the place group in each experiment, the location of the platform was indicated by the shape of the pool and stimuli outside the pool (place cues), but not the landmarks within the pool. For the landmark groups, the landmarks, not the place cues, indicated where the platform could be found. During Stage 2, 2 of the place cues were relevant, and 2 of the landmarks were irrelevant, for a new discrimination. The place cues better controlled searching for the platform in the place group than in the landmark group when the place cues had initially been relevant by signaling the presence (Experiment 1) or the absence (Experiment 2) of the platform. The results show that animals pay more attention to relevant than irrelevant cues.

059 Pacemaker implantation using real-time ultrasound guidance for subclavian vein access

BackgroundSubclavian vein access using anatomical landmarks for guidance is widely used and is known to carry risks of serious complications. While the use of ultrasound imaging in cannulating the internal...

Real-Time Ultrasound-Guided Subclavian Vein Cannulation Versus the Landmark Method in Critical Care Patients

Fragou, Mariantina*; Gravvanis, Andreas*; Dimitriou, Vasilios*; Papalois, Apostolos†; Kouraklis, Gregorios‡; Karabinis, Andreas§; Saranteas, Theodosios∥; Poularas, John*; Papanikolaou, John¶; Davlouros, Periklis**; Labropoulos, Nicos††; Karakitsos, Dimitrios* Author Information