Identification of interfascial plane using injection pressure monitoring at the needle tip during ultrasound-guided TAP block in cadavers

INTRODUCTION

Consistency in needle tip positioning within interfascial planes while performing infiltrative blocks under ultrasound guidance can be difficult. The exact determination of such planes may beyond the physical limits of common ultrasound machines. Aim of this pilot study was to understand if real-time continuous injection pressure monitoring at the needle tip, combined with ultrasound guidance, can help to immediately and consistently identify an interfascial plane needle tip placement.

METHODS

We performed four ultrasound-guided transversus abdominis plane (TAP) blocks on fresh cadaver using a modified conventional peripheral nerve block needle. The sensing needle contains Fabry-Perot miniaturized pressure sensor floating at the needle tip, connected to a measuring unit via an optical fiber. Injection-pressure measured at the needle tip was continuously recorded, while the needle was advanced toward the target and 0.9% saline was continuously injected via an electronic pump.

RESULTS

A recognizable, recurrent three-peaks injection pressure pattern was identified, while advancing the needle through the abdominal wall, the pressure peaks being identified with the needle to fasciae contact. In four different blocks, a total of 12 peaks and 12 troughs were identified. The mean injection pressure (95% CI) of the peaks varied substantially from the mean injection pressure of the troughs, from 119.55 kPa (95% CI 87.3 to 151 kPa) to 30.99 kPa (95% CI 12.5 to 47.5 kPa), respectively. The peaks (troughs) arose from reproducible pressure curves and were related to the needle tip encountering the muscle fasciae.

CONCLUSION

The identified injection pressure pattern, together with ultrasound image, may help in determine real-time the needle tip position, while performing a TAP block.

City consumption profile: a city perspective on the spending behavior of citizens

In designing the city of the future, city managers and urban planners are driven by specific citizens' behaviors. In fact, economic and financial behaviors, and specifically, which goods and services citizens purchase and how they allocate their spending, are playing a central role in planning targeted services. In this context, cashless payments provide an invaluable data source to identify such spending behaviors. In this work, we propose a methodology to extract the consumption behaviors of a large sample of customers through credit card transaction data. The main outcome of the methodology is a concise representation of the economic behavior of people residing in a city, the so-called city consumption profile. We inferred the city consumption profile from a network-based representation of the similarity among the customers in terms of purchase allocation; on top of which we applied a community detection algorithm to identify the representative consumption profiles. By applying the above methodology to a set of credit card transactions of an Italian financial group, we showed that cities, even geographically close, exhibit different profiles which makes them unique. Specifically, usage patterns focused on a single type of good/service-mono-categorical consumption profile-are the main factors leading to the differences in the city profiles. Our analysis also showed that there is a group of consumption profiles common to all cities, made up by purchases of primary goods/services, such as food or clothing. In general, the city consumption profile represents a tool for understanding the economic behaviors of the citizens and for comparing different cities. Moreover, city planners and managers may use it in the outline of city services tailored to the citizens' needs.

Early detection of intraneural and intravascular injections with real-time injection pressure monitoring in cadavers

BACKGROUND AND OBJECTIVES

Injection pressure monitoring can help detecting the needle tip position and avoid intraneural injection. However, it shall be measured at the needle tip in order to be accurate and reproducible with any injection system and non operator-dependent. With an innovative system monitoring the injection pressure right at the needle tip we show that it is possible to early detect an intraneural and also an intravascular injection.

METHODS

We performed supraclavicular block-like procedures under real-time ultrasound guidance on two fresh cadaver torsos using a sensing needle with an optical fiber pressure sensor within the shaft continuously measuring injection pressure at the needle tip. A total of 45 ultrasound-guided injections were performed (15 perineural, 15 intraneural and 15 intravenous injections).

RESULTS

Mean (SD) injection pressure after only 1 mL injected volume was already significantly higher for the intraneural compared to the perineural injections: 70.46 kPa (11.72) vs 8.34 (4.68) kPa; P < .001. Mean (SD) injection pressure at 1 mL injected volume was significantly lower for the intravascular compared to the perineural injections: 1.51 (0.48) vs 8.34 (4.68) kPa; P < .001.

CONCLUSIONS

Our results show that injection pressure monitoring at the needle tip has the potential to help identifying an accidental intraneural or intravascular injection at a very early stage.

Real-time continuous monitoring of injection pressure during peripheral nerve blocks in fresh cadavers

BACKGROUND

The incidence of unintentional intraneural injection while performing peripheral nerve block has been estimated to be 15% under real-time ultrasound guidance. Injection pressure increase may detect an intraneural injection. Real-time injection pressure changes throughout an entire nerve block procedure in relationship with needle tip location have never been reported.

METHODS

A new method was developed to precisely monitor the injection pressure curve during nerve blocks, based on a miniaturised Fabbri-Perrot pressure sensor. We tested in three fresh cadavers the ability of continuous pressure monitoring to discriminate between different tissues, as the injection pressure curve ascending slope, shape and plateau pressure value depend on tissue compliance. Injections of saline were performed by an electronic syringe pump with three different constant flow rates. Pressure was measured simultaneously at the tip and in the tubing of the needle.

RESULTS

At 10 mL/min injection flow, median peak injection pressure in the intraneural group at the needle tip was 315 mmHg, while at the perineural location it was 100 mmHg (p < 0.05). Median injection pressure was 95 mmHg in the intramuscular locations group, and 819 mmHg when a muscular fascia was indented (p < 0.05). A significant difference was noted for pressure measurements between the proximal port of the needle and the tip, 625 and 417 respectively.

CONCLUSIONS

Based on significant differences in injection pressure values and curve shapes, the system was able to discriminate between four needle tip locations. This may help with needle tracking while performing a peripheral nerve block.

Multidimensional human dynamics in mobile phone communications

In today's technology-assisted society, social interactions may be expressed through a variety of techno-communication channels, including online social networks, email and mobile phones (calls, text messages). Consequently, a clear grasp of human behavior through the diverse communication media is considered a key factor in understanding the formation of the today's information society. So far, all previous research on user communication behavior has focused on a sole communication activity. In this paper we move forward another step on this research path by performing a multidimensional study of human sociality as an expression of the use of mobile phones. The paper focuses on user temporal communication behavior in the interplay between the two complementary communication media, text messages and phone calls, that represent the bi-dimensional scenario of analysis. Our study provides a theoretical framework for analyzing multidimensional bursts as the most general burst category, that includes one-dimensional bursts as the simplest case, and offers empirical evidence of their nature by following the combined phone call/text message communication patterns of approximately one million people over three-month period. This quantitative approach enables the design of a generative model rooted in the three most significant features of the multidimensional burst - the number of dimensions, prevalence and interleaving degree - able to reproduce the main media usage attitude. The other findings of the paper include a novel multidimensional burst detection algorithm and an insight analysis of the human media selection process.