Needle Damage Research Articles

HOOKED EPINEPHRINE AUTO-INJECTOR DEVICES IN CHILDREN – FOUR CASE REPORTS WITH THREE DIFFERENT PROPOSED MECHANISMS

Introduction The prevalence of epinephrine auto-injectors (EAI) use is on the rise. Methods This case series describes four children with hooked EAI needles that were embedded in soft tissues. Results Two children (ages 5 and 7) who were curious about EAIs self-injected in their shins. The EAIs embedded beneath the skin and required removal in the Emergency Department. On removal, the needles were both hooked and splayed at the tip. A 16-month-old boy in anaphylaxis kicked his leg during EAI injection and the hooked needle embedded under his skin. A 4-year-old girl had an EAI administered for anaphylaxis, which was difficult to dislodge. On removal, the needle tip was hooked approximately 160 degrees. Images of the device revealed that the needle fired off-center from the device and the device components were cracked. We propose three different explanations for these hooked EAI needles. The first is that the needle could hit bone during injection and curve rather than penetrate further. Secondly, the needle could bend when the patient moves during injection. Thirdly, if a needle fires sufficiently off-center to hit the cartridge carrier, this could hook the needle prior to injection. Conclusions Awareness of the reasons for needle hooking, the needle damage observed, and challenges and successful approaches to their removal, can better prepare the provider for these uncommon events. Teaching parents, children and educators about safe EAI storage and appropriate restraint during use may prevent some of these accidental injuries. Reporting device failures may lead to improvements in device performance and design.

Thinning treatments reduce severity of foliar pathogens in eastern white pine

The foliar fungal pathogens associated with the disease complex known as White Pine Needle Damage (WPND) are causing widespread defoliation of eastern white pine (Pinus strobus L.) in the northeastern United States and Canada. Presently, there are no specific management recommendations for addressing declining stand health relating to WPND induced defoliations. This study aims to test the effects of thinning at two different residual stocking densities (14 and 25 m2 ha−1) on mitigating the negative impacts of WPND within infected stands. To quantify the impacts of WPND on individual tree health, we generated a composite health index score using response variables measured in the field and weighted according to their association with observations of WPND severity. Post-thinning changes in disease severity were used to evaluate the effectiveness of stand thinning to reduce pathogen pressure and promote overall tree vigor. Results show that thinning had a rapid positive effect on overall tree health, with no significant difference between thinning treatment levels in the first two years following tree removal. Severity of WPND was reduced by 35% in low-density residual thinnings in the second year of the study. Our findings suggest that thinning as a silvicultural tool to reduce stocking densities within infected stands can effectively promote overall tree health and maintaining proper stocking densities is recommended for stands at risk of infection.

Impacts of White Pine Needle Damage on seasonal litterfall dynamics and wood growth of eastern white pine (Pinus strobus) in northern New England

White Pine Needle Damage (WPND) is a complex of foliar fungal pathogens that have established as a chronic disease impacting eastern white pine (Pinus strobus L.) stands in the northeastern United States. With long-term ecological and economic impacts in mind, it is critical to quantify the negative effects of this disease on tree and forest health in order to make informed management decisions. We measured litterfall to determine the timing and magnitude of WPND-induced defoliation across four study sites in the northeastern US between 2014–2016. We measured N concentrations of needles cast throughout the 2014 growing season to estimate total litter N flux resulting from WPND. Additionally, to quantify growth declines we measured annual basal area increment (BAI) from six symptomatic study sites in the infected region. We found that WPND-induced defoliation in the months of June and July accounted for 47% of the total annual litterfall across the study sites, often exceeding normal needle senescence in October. Foliar %N in June and July was 0.78 and 0.84% respectively, significantly higher than October concentrations of 0.40%, suggesting incomplete resorption of N during the summer months. Untimely summer defoliations resulted in a mean estimated N loss of 0.92 g N m−2 yr−1, representing 63% of the total growing season N input from foliage. Growth of symptomatic trees at all sites was reduced following outbreaks of WPND initiating between 2007–2009. Severely infected trees reduced BAI 25–73% compared to pre-outbreak years. Our results show that WPND-induced defoliation significantly alters litterfall and N dynamics of affected stands, and suggest that subsequent N limitation in addition to reduced foliar area greatly reduces annual wood growth within infected stands.

Effect of Climatic Variables on Abundance and Dispersal of Lecanosticta acicola Spores and Their Impact on Defoliation on Eastern White Pine.

The disease complex white pine needle damage (WPND), first reported in 2006, has now escalated to an epidemic state across the northeastern United States. Although this complex is composed of several fungal species, Lecanosticta acicola is considered to be the primary causal agent. Knowledge regarding the epidemiology, specific climatic factors that affect the spread of L. acicola on eastern white pine (Pinus strobus) in natural forest settings, and potential risks repeated defoliation may have on tree health is limited. Therefore, this study examined how climatic variables affect the abundance and distance of spore dispersal of L. acicola and compared litterfall caused by defoliation versus natural needle abscission. Conidia were observed on spore traps from May through August, with a peak in abundance occurring in June, corresponding to the defoliation of second- and third-year foliage measured in litter traps. During peak spore production, relative humidity and the occurrence of rainfall was found to have the greatest influence on spore abundance. Our results will aid managers in determining how far from infected trees natural regeneration will likely be affected and predicting future disease severity based on climatic conditions.

Ectomycorrhizal fungi increase the vitality of Norway spruce seedlings under the pressure of Heterobasidion root rot in vitro but may increase susceptibility to foliar necrotrophs

We tested if root colonisation by ectomycorrhizal fungi (EMF) could alter the susceptibility of Norway spruce (Picea abies) seedlings to root rot infection or necrotic foliar pathogens. Firstly, spruce seedlings were inoculated by various EMF and challenged with Heterobasidion isolates in triaxenix tubes. The ascomycete EMF Meliniomyces bicolor, that had showed strong antagonistic properties towards root rot causing Heterobasidion in vitro, protected spruce seedlings effectively against root rot. Secondly, spruce seedlings, inoculated with M. bicolor or the forest humus, were subjected to necrotrophic foliar pathogens in conventional forest nursery conditions on peat substrates. Botrytis cinerea infection after winter was mild and the level of needle damage was independent of substrate and EMF colonisation. Needle damage severity caused by Gremminiella abietina was high in seedlings grown in substrates with high nutrient availability as well as in seedlings with well-established EMF communities. These results show that albeit M. bicolor is able to protect spruce seedlings against Heterobasidion root rot in axenic cultures it fails to induce systemic protection against foliar pathogens. We also point out that unsterile inoculum sources, such as the forest humus, should not be considered for use in greenhouse conditions as they might predispose seedlings to unintended needle damages.

The effects of needle damage on annulus fibrosus micromechanics.

Needle puncture of the intervertebral disc can initiate a mechanical and biochemical cascade leading to disc degeneration, but the link between the local damage of the puncture and the disc-wide effects is not well understood. This work aimed at determining the micro-mechanical effects of the puncture far from its site, and to observe the damage induced by the puncture with high resolution imaging. Results show that the puncture had modest effect far from the puncture, but lumps of tissue were left by the needle, detached from the disc; these could cause further damage through friction and inflammation of the surrounding tissues. This suggests that the cascade leading to degeneration is probably driven by a biochemical response rather than disc-wide mechanical effects.

Towards improved comparability of studies addressing atmospheric concentrations of semivolatile organic compounds based on their sequestration in pine needles

Coniferous needles can be used as a passive air sampler of semivolatile organic compounds (SVOC) and an indicator of atmospheric pollution patterns and trends. There is limited information on whether different parts of the plant (e.g., foliage leaves, dwarf shoots, twig, etc.) contain different levels of SVOC. Only few studies have compared levels of SVOC surface layer of wax and to their total content in all needle tissues and what affects an uptake and distribution of SVOC. It is important to have better understanding of the extent to which sampling and sample preparation procedures affect measured levels of SVOC in pine needles and reduce comparability of data from samples processed in different ways. In the present study, we assessed an impact of various sampling and sample preparation techniques on the levels of SVOC in Pinus sylvestris needles. While the impact of various storing, washing and drying methods was not significant, presence of dwarf shoots in the sample or structural damage of needles affected the results significantly. Results show that levels of SVOC in dwarf shoots are 2–8 times higher than those in foliage leaves. Therefore, dwarf shoots must be carefully removed before foliage leaves extraction to improve comparability of results. There were different patterns in SVOC on the surface of the foliage leaves compared to the whole leaves. An uptake of these substances by the surface wax as well as their occurrence in the internal structure was of function of the physico-chemical properties of the substances (log Kow, molar weight).

Combined effects of irrigation amount and nitrogen load on growth and needle biochemical traits of Cryptomeria japonica seedlings

Growth of C. japonica under highly irrigated and N-loaded soil is noticeable because of N-induced increase of needle mass and alleviation of high irrigation-induced reduction in photosynthesis. To clarify the combined effects of change in precipitation amount and increasing nitrogen load on Japanese forest trees, 2-year-old seedlings of Cryptomeria japonica were treated with combinations of four irrigation levels (80, 100, 120, or 140% of annual precipitation) and three nitrogen loads (15, 50, or 100 kg ha−1 year−1). The 100% of annual precipitation corresponded to 1520 mm year−1 which was the average annual precipitation in the habitats of C. japonica in Japan. High irrigation amount significantly enhanced the whole-plant dry mass of the seedlings. The N load significantly enhanced the extent of high irrigation-induced increase in needle dry mass. As a result, the irrigation-induced increase in the whole-plant dry mass was greater in the treatment with the highest N. However, increase in needle dry mass induced by high irrigation enhanced plant water consumption and caused dehydration and oxidative damage in needles, thus resulting in reduced net photosynthetic rate. The high irrigation-induced reduction in net photosynthetic rate was alleviated by N load. This alleviation was not caused by N load-induced changes in antioxidative capacity but by a N load-induced increase in ribulose 1,5-bisphosphate carboxylase/oxygenase activity. These results indicate that an increase in the whole-plant dry mass of C. japonica seedlings grown in highly irrigated and N-loaded soil was attributed to N load-induced enhancement of high irrigation-induced increase in needle dry mass and alleviation of high irrigation-induced reduction in net photosynthetic rate.

The effect of surface fire on tree ring growth of Pinus radiata trees

Pinus radiata trees showed significantly reduced basal area increments and increased latewood/earlywood ratios, when their stem was charred by surface fires even if no needle damage occurred. An interaction of fire damage and precipitation on growth was observed. Heat from forest fires is able to penetrate beyond the bark layer and damage or completely kill a tree’s cambium. Short-term growth reductions following surface fires have been reported for some species. However, most studies have in common that they describe a compound effect of stem and foliage damage. This study investigated the impact of surface fires on the radial growth of Pinus radiata, where only the stem of trees was charred, while no needle damage was recorded. Tree ring measurements were performed on cores obtained at breast height. Analysis of variance and tests, based on annual basal area increment values were calculated to quantify pre- and post-fire growth differences of tree ring width and latewood/earlywood ratios. The analysis revealed significant growth reductions following a surface fire on P. radiata in the year on which the fire occurred as well as in the following year. As a consequence of the fire, basal area increment and latewood/earlywood ratios were significantly reduced. An interaction of fire damage and precipitation on growth was observed. The obtained results show how fires without crown damage can affect growth and tree ring structure of P. radiata trees and indicate that stem char could be associated with a significant decrease in ring width and latewood/earlywood ratio.

Emergence of white pine needle damage in the northeastern United States is associated with changes in pathogen pressure in response to climate change.

The defoliation of the eastern white pine (Pinus strobus) across the northeastern United States is an escalating concern threatening the ecological health of northern forests and economic vitality of the region's lumber industry. First documented in the spring of 2010 affecting 24328 hectares in the state of Maine, white pine needle damage (WPND) has continued to spread and is now well established in all New England states. While causal agents of WPND are known, current research is lacking in both sampling distribution and the specific environmental factor(s) that affect the development and spread of this disease complex. This study aims to construct a more detailed distribution map of the four primary causal agents within the region, as well as utilize long-term WPND monitoring plots and data collected from land-based weather stations to develop a climatic model to predict the severity of defoliation events in the proceeding year. Sampling results showed a greater distribution of WPND than previously reported. WPND was generally found in forest stands that compromised >50% eastern white pine by basal area. No single species, nor a specific combination of species had a dominating presence in particular states or regions, thus supporting the disease complex theory that WPND is neither caused by an individual species nor by a specific combination of species. In addition, regional weather data confirmed the trend of increasing temperature and precipitation observed in this region with the previous year's May, June, and July rainfall being the best predictor of defoliation events in the following year. Climatic models were developed to aid land managers in predicting disease severity and accordingly adjust their management decisions. Our results clearly demonstrate the role changing climate patterns have on the health of eastern white pine in the northeastern United States.

Effects of winter warming on cold hardiness and spring budbreak of four boreal conifers

Compared with the effects of spring frosts on opening buds or newly flushed tissues, winter freezing damage to conifers, owing to temperature fluctuations prior to budbreak, is rare and less known. In this study, changes in cold hardiness (measured based on electrolyte leakage and needle damage) and spring budbreak were assessed to examine the responses of four boreal conifer species — black spruce (Picea mariana (Mill.) B.S.P.), white spruce (Picea glauca) (Moench) Voss), jack pine (Pinus banksiana Lamb.), and lodgepole pine (Pinus contorta Dougl. ex. Loud.) — to different durations of experimental warming (16 °C day to –2 °C night with a 10 h photoperiod, except for night temperatures during November warming (+2 °C)). Seedlings showed increased responses to warming from November to March, while the capacity to regain the cold hardiness lost to warming decreased during the same period. This suggests an increasing vulnerability of conifers to temperature fluctuations and freezing damage with the progress of chilling and dormancy release from fall to spring. Both lodgepole pine and jack pine initiated spring growth earlier and had greater responses to experimental warming in bud phenology than black spruce and white spruce, suggesting a greater potential risk of frost/freezing damage to pine trees in the spring.

Limited variation found among Norway spruce half-sib families in physiological response to drought and resistance to embolism.

Projections of future climates suggest that droughts (Ds) may become more frequent and severe in many regions. Genetic variation, especially within populations in traits related to D resistance, is poorly investigated in forest trees, but this knowledge is necessary to better understand how forests will respond to water shortages. In this study, we investigated variability among seven open-pollinated half-sib families of a single population and two population-level progenies of Norway spruce (Picea abies (L.) H. Karst.) in their gas exchange response to imposed D and xylem vulnerability to embolism. During their third growing season, saplings were subjected to three treatments-control (C), D (for 19 weeks) and broken drought (BD, 54 days without watering starting in mid-July, then well-watered). In response to D, all families reduced their stomatal conductance (gs) and light-saturated rates of photosynthesis (Amax) in a similar way. After rewatering, the xylem water potential (Ψ) recovered in the BD treatment, but gs and Amax remained lower than in C. Needle starch concentration was altered in both D treatments compared with C. Xylem of D-exposed trees was more vulnerable to embolism than in C. The minimum attained safety margin remained positive for all families, indicating that no catastrophic hydraulic failure occurred in stem xylem during D. Significant family variation was found for Ψ early in the D (midday Ψ between -1.2 and -1.8 MPa), and for needle damage, but not for sapling mortality. Family variation found at the initial stages of D, and not afterward, suggests that all families responded similarly to greater D intensity, exhibiting the species-specific response. Limited variation at the family level indicates that the response to D and the traits we examined were conservative within the species. This may limit breeding opportunities for increased D resistance in Norway spruce in light of expected climatic changes.

A novel technique of needle setting for curvilinear endobronchial ultrasound: Improved efficiency with no cost.

Background:Standard instructions for biopsy using the convex curvilinear endobronchial ultrasound scope include visualization and adjustment of the sheath housing the biopsy needle before every puncture. In our practice, we pre-set this relationship before inserting the endobronchial ultrasound scope and leave it fixed for every puncture.Objective:We postulated that this approach is more efficient than repeated re-adjustment and aimed to show that it would not increase the frequency of endobronchial ultrasound scope damage.Methods:Retrospective review of every biopsy using the endobronchial ultrasound scope over a 6-year period with documentation of damages and costs.Results:There were 15 scope damages out of 1792 procedures (0.8%). Eight damages were determined to be due to needle damage, one due to patient bite, three due to Williams airway abrasions, and three were camera failures. All damages occurred during the first 5 years of the study. Costs totaled US$138,725, for an average of US$23,120 per year. This rate of damages appears to be similar to or lower than that reported when standard instructions are followed.Conclusion:Pre-setting of the biopsy needle when the endobronchial ultrasound scope is used leads to greater efficiency and no increase in scope damages.

Characterization of Fungal Pathogens Associated with White Pine Needle Damage (WPND) in Northeastern North America

Eastern white pine is a crucial ecological and economic component of forests in the northern USA and eastern Canada, and is now facing an emerging problem in white pine needle damage (WPND). It is still unclear whether WPND results from one, or the combination of several fungal pathogens. Therefore, the first objective of this study was to characterize the fungi associated with WPND in the northeastern United States and document the damage being done to mature eastern white pine as a result of repeated defoliation. To date, 22 species of fungi, either cultured from diseased pine needles or formed fruiting bodies on pine needles were identified based on morphology and sequence data. Lecanosticta acicola and a putative new species of Septorioides were the species most frequently recovered from diseased needles, in addition to needle cast fungi Lophophacidium dooksii and Bifusella linearis, two obligate fungal pathogens that were frequently observed on pine needles in the northeast, but have not been known to cause excessive defoliation of eastern white pine. A second objective was to monitor yearly the health of 63 pairs of healthy and unhealthy trees in eight affected locations throughout New England. Since 2012, affected trees are increasingly and repeatedly chlorotic and defoliated every year. Trees that were initially healthy are now exhibiting symptoms. While L. acicola appears to be the primary pathogen causing WPND, several other common needle pathogens are being more frequently observed and the role of climate change may be important in the disease ecology of WPND. These defoliation events, while once a sporadic occurrence, have now become more frequent as observed in continued crown deterioration of eastern white pine in long-term monitoring plots followed during the course of this three-year study.

Effects of light exposure in freezing temperatures on winter damage to foliage of Norway spruce container seedlings in mid and late winter: Pilot experiments in an open field

Norway spruce (Picea abies (L.) Karst.) is widely planted for reforestation in the boreal zone. It is sensitive to frost and high irradiance during the growing season, and also to winter damage, which cause growth losses in reforestation. This study made a pilot attempt to examine the needle damage and seedling vigour on hardened Norway spruce seedlings under freezing temperatures using natural and artificial light exposure from a day to weeks in an open field in mid and late winter in central Finland. The treatments induced needle browning and decreased seedling vigour, which reduced shoot and root growth during the following growing season. Visibly damaged, mottled needles of one-year terminal shoots had practically no healthy-looking cells. The new buds, however, were healthy and were able to grow during the following season. Our results suggests that, above the snow cover, the freezing temperatures and wind, rather than the intensity of light radiation, induced the observed needle damage found immediately after the treatments, and the subsequent growth reduction in the following growing season. The preliminary methods used outdoors could not distinguish all the different environmental conditions and their mechanisms of effects on seedlings, which demonstrates the need for further method development in controlling experimental conditions of air temperature, radiation intensity, and air current in future research of seedling winter damage outdoors.

In vivo evaluation of needle force and friction stress during insertion at varying insertion speed into the brain.

Convection enhanced delivery (CED) infuses drugs directly into brain tissue. Needle insertion is required and results in tissue damage which can promote flowback along the needle track and improper targeting. The goal of this study was to evaluate friction stress (calculated from needle insertion force) as a measure of tissue contact and damage during needle insertion for varying insertion speeds. Forces and surface dimpling during needle insertion were measured in rat brain in vivo. Needle retraction forces were used to calculate friction stresses. These measures were compared to track damage from a previous study. Differences between brain tissues and soft hydrogels were evaluated for varying insertion speeds: 0.2, 2, and 10mm/s. In brain tissue, average insertion force and surface dimpling increased with increasing insertion speed. Average friction stress along the needle-tissue interface decreased with insertion speed (from 0.58 ± 0.27 to 0.16 ± 0.08 kPa). Friction stress varied between brain regions: cortex (0.227 ± 0.27 kPa), external capsule (0.222 ± 0.19 kPa), and CPu (0.383 ± 0.30 kPa). Hydrogels exhibited opposite trends for dimpling and friction stress with insertion speed. Previously, increasing needle damage with insertion speed has been measured with histological methods. Friction stress appears to decrease with increasing tissue damage and decreasing tissue contact, providing the potential for in vivo and real time evaluation along the needle track. Force derived friction stress decreased with increasing insertion speed and was smaller within white matter regions. Hydrogels exhibited opposite trends to brain tissue.

Infection with foliar pathogenic fungi does not alter the receptivity of Norway spruce seedlings to ectomycorrhizal fungi

We studied whether the induction of defence against foliar pathogens affects the interaction of Norway spruce (Picea abies) with ectomycorrhizal fungi (EMF) and whether the response differs between seedlings originating from families showing variable growth performance in long-term trials. The shoots were inoculated with Botrytis cinerea and Gibberella avenacea. The roots were simultaneously inoculated with sieved humus to provide the EMF inoculum. The severity of the pathogenic infection was based on the amount of damage and induced production of condensed tannins in the needles. EMF richness and colonisation were not affected by the pathogens and were also identical between the fast- and slow-growing seedlings. The fast-growing seedlings were more vulnerable to the pathogens; however, the constitutive level of condensed tannins in the needles did not correlate with their susceptibility to either the pathogenic or symbiotic fungi. G. avenacea induced a marginally greater production of condensed tannins in the slow-growing seedlings, which was linked to a slight reduction in EMF richness and less needle damage after wintering. Our results suggest that there are differences in resource allocation strategies between the fast- and slow-growing spruce families, which may indicate the presence of underlying host effects that regulate interactions with associated fungi.

Undisturbed and disturbed above canopy ponderosa pine emissions: PTR-TOF-MS measurements and MEGAN 2.1 model results

Abstract. We present the first eddy covariance flux measurements of volatile organic compounds (VOCs) using a proton-transfer-reaction time-of-flight mass spectrometer (PTR-TOF-MS) above a ponderosa pine forest in Colorado, USA. The high mass resolution of the PTR-TOF-MS enabled the identification of chemical sum formulas. During a 30 day measurement period in August and September 2010, 649 different ion mass peaks were detected in the ambient air mass spectrum (including primary ions and mass calibration compounds). Eddy covariance with the vertical wind speed was calculated for all ion mass peaks. On a typical day, 17 ion mass peaks, including protonated parent compounds, their fragments and isotopes as well as VOC-H+-water clusters, showed a significant flux with daytime average emissions above a reliable flux threshold of 0.1 mg compound m−2 h−1. These ion mass peaks could be assigned to seven compound classes. The main flux contributions during daytime (10:00–18:00 LT) are attributed to the sum of 2-methyl-3-buten-2-ol (MBO) and isoprene (50%), methanol (12%), the sum of acetic acid and glycolaldehyde (10%) and the sum of monoterpenes (10%). The total MBO + isoprene flux was composed of 10% isoprene and 90% MBO. There was good agreement between the light- and temperature dependency of the sum of MBO and isoprene observed for this work and those of earlier studies. The above canopy flux measurements of the sum of MBO and isoprene and the sum of monoterpenes were compared to emissions calculated using the Model of Emissions of Gases and Aerosols from Nature (MEGAN 2.1). The best agreement between MEGAN 2.1 and measurements was reached using emission factors determined from site-specific leaf cuvette measurements. While the modeled and measured MBO + isoprene fluxes agree well, the emissions of the sum of monoterpenes is underestimated by MEGAN 2.1. This is expected as some factors impacting monoterpene emissions, such as physical damage of needles and branches due to storms, are not included in MEGAN 2.1. After a severe hailstorm event, 22 ion mass peaks (attributed to six compound classes plus some unknown compounds) showed an elevated flux for the two following days. The sum of monoterpene emissions was 4–23 times higher compared to emissions prior to the hailstorm while MBO emissions remained unchanged. The monoterpene emission (in mg compound m−2) during this measurement period is underestimated by 40% if the effect of this disturbance source is not considered.

Experimental Testing and Finite Element Modeling of Bump Wafer Probing

The purpose of this paper is mainly to develop a method to simulate the bump height variation and probe mark profile for Eutectic (Sn63/ Pb37) bump wafer probing with continuing-touchdown probing. Certainly, the bump height variation and probe mark area on the solder bump influence the quality of the wafer probing and further impacts reliability of the packaging process after wafer probing to cause issues of cold-joint and needle damage. A three-dimensional computational model of was developed to analyze the contact phenomena between the vertical needle and the solder bump. Finite element simulation software, ANSYS, is used to analyze the loading force distributed on the vertical needle with various overdrives. In addition, the results of the bump height variation and probe mark area, which predicted by the finite element method (FEM), were verified against the on-line experimental results. Finally, the results predicted by the finite element model is consistent with experimental results and the numerical method presented in the paper can be used as a useful evaluating method to support the choice of suitable probe geometry and wafer probe testing parameters.

Ultrasound-guided thoracic paravertebral block using the SonixGPS® system in human cadavers

To the Editor, The recent case report on spinal anesthesia using the SonixGPS (Ultrasonix, Richmond, BC, Canada) needle tracking system prompted us to share our recent experience using the same system to perform paravertebral blocks in cadavers. Locating the paravertebral space can be technically difficult due to the depth of the paravertebral space relative to the skin. In addition, the probe position and the acute angle of needle trajectory render the tip and distal portion of the needle difficult to visualize when concurrently viewing the anatomical structures using conventional ultrasound techniques. Theoretically, the SonixGPS system may be useful for performing paravertebral blocks owing to its ability to provide a real-time display of needle trajectory and to facilitate needle-beam alignment. Three unembalmed cadavers (two female, one male; median [range] height, 175 [173-178] cm; body mass index, 18.2 [13.1 to 27.1]) in the Department of Cellular and Physiological Sciences of the University of British Columbia were studied after approval by The University of British Columbia Research Ethics Board. In prone cadavers, four thoracic paravertebral levels (T5, T7, T9, and T11) were scanned, and paravertebral blocks were performed using a 5-14 MHz linear transducer (Ultrasonix, Richmond, BC, Canada) and an 8-cm 19G SonixGPS needle. At each level, the transverse process, paravertebral space, lamina, and superior costotransverse ligament were identified after scanning laterally to locate the ribs. The ultrasound probe was placed in a parasagittal plane while the needle was directed via an in-plane or an out-of-plane approach. For an in-plane block, once the paravertebral space was located, the needle was directed in a cephalad trajectory using the SonixGPS (Figure, Panel A). For out-of-plane blocks, the needle was advanced toward the paravertebral space in a lateral to medial trajectory determined by the SonixGPS. Once the needle tip was situated in the paravertebral space, methylene blue dye 1 mL was injected and a guidewire was inserted to demarcate the location. The procedure was performed at four levels (T5, T7, T9, and T11) for each cadaver using an out-of-plane approach on one side and an in-plane approach on the opposite side. An anatomist mapped the extent of dye spread in the paravertebral space by performing dissections in a layerwise fashion at each level following the inserted guidewires. Anatomical structures in the paravertebral space stained by dye were documented and photographed. A clamshell incision of the thorax was also performed with evisceration of the contents to examine carefully for evidence of pleural puncture. The paravertebral space, superior costotransverse ligament, and transverse processes were identified in all three cadavers at all levels. Clear images of the paravertebral space were obtained at all levels with the in-plane and the out-of-plane approaches (Figure, Panel A). Dissection showed discrete segmental spread of methylene dye in 20 injections (Figure, Panel B). The dye was seen to stain the segmental nerve roots and sympathetic chain. There was no evidence of pleural puncture, and methylene blue could be seen outside the pleura. Four injections in the cadaver study were abandoned due to damage to the needles during injection, which led to failure to inject dye. Needle damage consisted of bending due to poor tensile strength of the needles and the relatively dense nature of the paraspinal muscles, tissue, and skin of the cadavers. SonixGPS needle B. Kaur, MBBS R. Tang, MD H. Vaghadia, MD (&) A. Sawka, MD Vancouver Coastal Health, Vancouver, BC, Canada