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Why should I use the BSmart™?
BSmart™ is designed to provide clinicians with objective information on the injection pressure. The pressure information is used to complement the traditionally used tactile or syringe “hand feel” and standardize nerve block injection. The use of BSmart™ will simply detect and prevent injection into a poorly compliant tissue (e.g., nerve fascicles, tendon, other tight tissue compartments). The pressure information is analogous to that provided by CVP, pulmonary artery catheters, and other monitors. It is up to the clinician to decide how and whether to use the information provided by BSmart™
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Does BSmart™ require modification of nerve block techniques?
- No. Nerve localization, aspiration and injection is identical as in procedures without BSmart™
- BSmart™ is simply inserted between the syringe and the needle tubing and unobtrusively provides pressure information.
- During the injection, the clinician still retains the traditional tactile feel but also has the benefit of the objective visual indication of the injection pressure provided by BSmart™
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Can the information provided by BSmart™ be used to document a nerve block technique?
YES. The information obtained by BSmart™ can be used to objectively document nerve block procedure.
- Resistance to injection is a part of the standard documentation procedure during nerve blockade (1).
- The documentation requires clinicians to document whether the resistance to injection was “normal” or “high” and the course of action if it was abnormal.(1)
- In the past, documentation of the resistance was merely subjective and relied on the “learned feel” and experience of the clinician
- Objective monitoring can be used to allow trainees to acquire the appropriate “feel” or for less experienced personal to inject using the controllable force of injection
- A note in the chart stating that the injection pressure was <20 psi unambiguously indicates that the resistance (pressure) was paid attention to during the procedure.
1. Reg Anesth Pain Med 2005;30:67-71.
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How is BSmart™ used?
- Attach female end of
BSmart™ to the syringe and the luer lock to the tubing of the nerve block needle.
- The BSmart™-tubing-needle is flushed and purged off air
- The piston of BSmart™ must move up and indicate pressure information during flushing
- Upon nerve localization, local anesthetic is injected while maintaining injection pressure <20 psi (white or yellow indicator on the piston of BSmart™)
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What does it mean when BSmart™ indicates injection pressure >20 psi?
- When BSmart™ indicates that the pressure required to inject local anesthetic is >20 psi, this means that the needle tip is either
- Obstructed (e.g., clot or tissue obstructing the needle lumen) or
- Inserted into a poorly compliant space (e.g., nerve fascicle, tendon, tight tissue compartment).
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Does the pressure information displayed by BSmart™ reliably indicate the pressure at the tip of the needle with different size of the syringe, needle and tubing or different speed of the injection?
Yes. There are two phases of fluid administration:
- 1. Isostatic phase – During this phase – there is no flow at the tip of the needle. A certain (opening) pressure must be reached within the syringe-tubing-needle system in order to INITIATE the injection into a tissue compartment. During this phase the pressure is equal throughout the entire closed system (including the needle opening; Pascal’s law) (2)
- 2. Dynamic phase – Once the opening pressure is overcome and the injection is initiated, the injection pressure becomes affected by the rate of injection and the flow characteristics of the fluid passages (Bernoulli’s principle) (3) .
- As long as the injection pressure is maintained <20 psi throughout the procedure, injection into a poorly compliant tissue can be avoided regardless of the syringe and needle size or the speed of injection.
2. Billings BH et a. : Fundamental concepts of mechanics. In American institute of physics. 3rd edition. Edited by Gray DE. McGraw-Hill, New York, NY, 1972, pp 2-14.
3. Marchioro C et al: Conservation laws. In Mathematical theory of incompressible nonviscous fluids. Edited by John F, Marsden JE, Sirovich L. Springer-Verlag, New York, NY, 1994, pp 24-5.
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What should one do when BSmart™ indicates injection pressure >20 psi?
- Throughout the injection of the local anesthetic, the injection pressure should be kept below 20 psi.
- When the piston of BSmart™ indicates >20 psi (red ring), the following steps should be undertaken:
- 1. Rotate the needle clock-wise or counter clock-wise while continuously applying the syringe pressure of <20 psi.
- This often (most of the time) dislodges the bevel of the needle from the non-compliant space and allows the injection to begin at <20 psi
- 2. If the above maneuver does not reduce the injection pressure to <20 psi, withdraw the needle 1-2 mm and re-attempt to inject.
- 3. If the maneuvers 1&2 do not result in the decrease of the injection pressure, do not assume that the needle is obstructed. Withdraw the needle, flush it to assure that it is clean off tissue debris or clot and repeat the procedure.
2. Billings BH et a. : Fundamental concepts of mechanics. In American institute of physics. 3rd edition. Edited by Gray DE. McGraw-Hill, New York, NY, 1972, pp 2-14.
3. Marchioro C et al: Conservation laws. In Mathematical theory of incompressible nonviscous fluids. Edited by John F, Marsden JE, Sirovich L. Springer-Verlag, New York, NY, 1994, pp 24-5.
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Can BSmart™ be used with Ultrasound guided blocks or continuous nerve blocks?
YES.
- The ultrasound imaging is of insufficient resolution to rule out intrafascicular needle placement. Therefore, the injection pressure information provided by BSmart™ is complementary in ultrasound-assisted nerve blocks.
- Continuous nerve blocks are placed with needles of larger gauge than single injection blocks; consequently, intraneural injection is less likely. However, catheters can still be placed intraneurally or in a tight (less compliant) compartment leading to the risk of intraneural injection or nerve ischemia.
- The injection pressure information provided by BSmart™ may be useful to assure catheter placement in a compliant space or to rule out catheter kink or malfunction (high injection pressure)
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Is the BSmart™ Latex free?
Yes, the BSmart™ is manufactured without the use of Latex.
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