Classic Syringe Pump

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Introduction

Infusion pumps are utilized to study the physiological and pharmacological characteristics of biological or pharmacological substances in vivo. Two distinct types of infusion pumps are present: syringe pumps and implantable pumps. A syringe pump is a small infusion device that is used to gradually administer specific amounts of fluids for use in chemical and biomedical research. It includes an outer syringe that is attached to a catheter from the animal. Syringe pumps either withdraw or push out fluid via a syringe to obtain a predetermined volume depending on the size of the syringe. The pressure that a syringe pump can produce is a function of the pump’s force and also the physical attributes of the syringe and the setup utilized.

Over the years, a variety of vascular infusion and intravascular delivery methods have been utilized in rodents with varying amounts of success in biomedical research. Since rodents are the most extensively used animal species in biomedical research, it is reasonable to anticipate that the need for enhancing the techniques for vascular infusion systems in rodents will advance in the future.  Fundamental research in fields like neuroscience, physiology, pharmacology, virology, immunology, and oncology utilize substantial quantities of rodents to evaluate the impact of biological and pharmacological active agents. A significant number of these studies depend on vascular infusion technology or to develop samples for the evaluation of movement, biodistribution, and plasma duration.

A syringe pump is the standard instrument for administering intravenous doses to rats and mice given its capacity to deliver small volumes accurately. In essence, the device guarantees precise administration of a drug. When the animal is set up for infusion or sample withdrawal, infusion and withdrawal techniques can be performed using manual or automated procedures. Manual infusion is performed with the syringe pump as syringes are connected to the catheters or pumps, which in turn can be attached to give unattended infusion.

The characteristics of a syringe pump vary extensively with regards to design type, flow rate, and precision. Types of designs include syringe, peristaltic, and piston pumps. Syringe pumps make use of a worm drive system, which drives the plunger of a standard syringe at a modifiable rate. Syringe pumps have a tendency to deliver low levels of flow with an accuracy of ±2%. The device can also be utilized for tethered infusion, where animals can be tethered for long duration infusions ranging from a span of several weeks to months. Syringe pumps can be set up for continuous pumping by using a reciprocating pumps program so that two pumps can be utilized together to make a constant infusion framework. This mode enables one pump to infuse while the other one withdraws.

There are two major types of syringe pumps: the medical infusion pump and the research syringe pump. The medical infusion pump is basically designed for the delivery of controlled amounts of fluids, for example, nutrients, drugs, and blood to patients. They are principally used for in vivo analysis, treatment, and research studies. On the other hand, research syringe pumps or the modern laboratory pumps are instruments utilized in research labs for applications that need very small amounts of fluid deliveries. Research pumps generally manage smaller volumes and provide additional characteristics that promote research yet are unfeasible for in vivo use. Moreover, the device offers better precision, a continuous flow and much better accuracy than their medical syringe counterparts.

Principle

As is evident by its name, the primary component of the syringe pump is the syringe. This instrument has been extensively utilized in medical settings for quite a long time. However, on its own, the syringe entails a hand driven movement of the piston, which is not appropriate for a controlled administration of its contents. The syringe pump was developed to resolve this issue. It comprises of a straightforward source of linear motion that controls the speed at which the piston is driven.

If the diameter of the syringe is known, the device adapts its linear speed to the required flow rate. The strength of the syringe pump lies in the fact that the user can effortlessly adjust the working range of the device by altering the diameter of the syringe. Generally, a smaller diameter syringe allows better control at lower flow rates yet at smaller dispensable volumes.  In contrast, a larger diameter allows control at larger volumes however reduces the performance of the device at low flow rates.

In addition, syringe pumps have the ability to determine the flow rate effectively. While changing flow rates, the piston pushes the syringe resulting in an increased amount of pressure in the fluidic system, and it is deformed instead of placing the fluid into motion. The flow stability of a syringe pump is decided by the negligible motion of its motor. Since the displacement of the piston and the injected volume are connected, this negligible motion incites an insignificant infused volume. In this way, distinct phenomena which resemble oscillations or pulses show up at low flow rates because of the motor step.

A syringe pump, like other infusion frameworks, can be largely described by its settling time and its dependability. The settling time of a syringe pump depends on the value of its mechanics, as well as, and all the more importantly, on the fluidic resistance and the fluidic compliance of the entire experimental system. It is important to remember that the elasticity in the system allows a smoother flow rate and improves its stability, but reduces its responsiveness. Hence, to obtain the best responsiveness with a syringe pump, elasticity in the fluidic framework must be prevented and the fluidic resistance of the chip ought to be reduced.

History

For more than a period of 50 years, researchers and scientists have utilized syringe pumps, with their capability to modulate the flow of fluids on a small level, to save lives and execute high-impact research studies. Initially, scientists created infusion pumps, of which syringe pumps are one type, for controlled delivery of drugs. In 1658, Christopher Wren developed the first infusion pump, but the development was slow due to technical restrictions, substandard blood transfusions and bans imposed by the government. New models appeared in the 19th century, and an infusion pump was first utilized for chemotherapy in the 1950s. Electronic pump development, productivity upgrades, and miniaturization of the pumps in the 1980s – 1990s expanded the use of infusion pumps in research.

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Precautions

To ensure the appropriate working of the plenum vaporizer systems, it is important that the system is supplied with pressurized gas. The vaporizer must be correctly attached, and locking mechanisms must be fully engaged to avoid any leakage of the agent and the gas. Vaporizers must not be overfilled or underfilled to prevent failure of the vaporizer systems. It is also important to ensure that the correct anesthetic agent is used to prevent over- or under-dosing the subject. Regular servicing of the vaporizer is also critical for its proper functioning.

Apparatus & Equipment

The primary components of the digital syringe pump typically comprise of the pusher block, syringe holder, and an internal stepper motor. The pusher block contacts the plunger and initiates the flow while the motor drives the plate. The syringe holder keeps the syringe in its place during the operation of the device.  The syringe pump also includes an LCD touchscreen interface that allows easy programming of flow rates and volumes.  Some models can even be linked to a computer to record the infusion history.

The linear force of the syringe pump is 18kg. It includes infusion or withdrawal settings. The dimensions are 27cm x 25cm x 12 cm. The stroke rate of the device is 0.0094mm/min-87.211mm/min whereas the stroke distance is 0.039um/step. The syringe pump has a flow rate of 0.001ul/min-138.7ml/min. The syringe size ranges from 0.5ul-140ml. The syringe pump has an accuracy of ±0.1% error <1%.

Protocol

Primarily, the aim of the syringe pump is to progressively administer precise doses of a drug while controlling the flow rate.  To ensure that the syringe pump can successfully accomplish its purpose, place the device on a clean and level surface.  Now, connect the power cord. Before turning the pump on, attach it to the electric switch utilizing the power cable. Attach the end of the power cord to the main socket at the back of the syringe pump. Now take the plug and attach it to the electric mains. Turn on the mains switch. The touchscreen display will indicate that the power is connected to the pump.

The next step is to make sure that the syringe is loaded accurately. Pinch and hold together the clutch lever that releases the clutch and force the syringe driver away until it touches the end of its track. Hold the clear syringe clamp; pull upward making room for the syringe in the syringe saddle. First put in the syringe barrel. Ensure that the syringe finger tabs are held by the metal holding spring, and discharge the syringe clamp in order to hold the syringe in the saddle safely. Pinch together the clutch lever and allow the syringe driver to progress forward until the point when the syringe driver touches the end of the disposable syringe plunger. Discharge the clutch lever so that the holding bars secure the end of the plunger to avoid siphoning. The syringe is at the moment correctly loaded.

Now, the syringe pump needs to be switched on. To turn on the pump, push the on button on the keypad. The instant you turn the pump on, it undergoes a self-test displaying various characters on the screen. When the self-test is finished, it will show on the screen. The infusion settings of the pump can be customized in a menu-driven procedure. The user can browse the rate modes provided on the start-up list; these modes are the most frequently utilized rate modes. The user can likewise utilize the option to select from saved programs, or the option to browse the list of additional standard rate modes.

After the pump has been successfully turned on, push the key to detect the syringe size and display it automatically. Ensure that the syringe size has been accurately identified. Program the delivery limit with the number or arrow keys and utilize the keys to verify the number. In the event that a delivery limit isn’t required, enter 0. Program the bolus amount with number or arrow keys and utilize the keys to verify the number. In the event that a bolus isn’t required, enter 0. Program the infusion rate with number or arrow keys, and press the keys to validate the rate.

Prior to beginning a delivery, the syringe should be primed to eliminate any residual air within the syringe tip and the infusion extension set and to remove any mechanical slack. Ensure that the infusion line is not attached to the animal when priming. Push the prime key to begin the process of priming. Leave the prime key as soon as all the air has been removed, and fluid starts to flow out of the infusion line. Now connect the catheter to the animal. Initiate the process of delivery by selecting the deliver option. Selecting the stop button will cease the process of delivery. Push and hold the power off button to turn off the pump. If the ac power is utilized, the pump will go into power-off/standby mode. In case the battery power is drained out, the pump will turn off.

Applications

Primarily, the aim of the syringe pump is to progressively administer precise doses of a drug while controlling the flow rate.  To ensure that the syringe pump can successfully accomplish its purpose, place the device on a clean and level surface.  Now, connect the power cord. Before turning the pump on, attach it to the electric switch utilizing the power cable. Attach the end of the power cord to the main socket at the back of the syringe pump. Now take the plug and attach it to the electric mains. Turn on the mains switch. The touchscreen display will indicate that the power is connected to the pump.

The next step is to make sure that the syringe is loaded accurately. Pinch and hold together the clutch lever that releases the clutch and force the syringe driver away until it touches the end of its track. Hold the clear syringe clamp; pull upward making room for the syringe in the syringe saddle. First put in the syringe barrel. Ensure that the syringe finger tabs are held by the metal holding spring, and discharge the syringe clamp in order to hold the syringe in the saddle safely. Pinch together the clutch lever and allow the syringe driver to progress forward until the point when the syringe driver touches the end of the disposable syringe plunger. Discharge the clutch lever so that the holding bars secure the end of the plunger to avoid siphoning. The syringe is at the moment correctly loaded.

Now, the syringe pump needs to be switched on. To turn on the pump, push the on button on the keypad. The instant you turn the pump on, it undergoes a self-test displaying various characters on the screen. When the self-test is finished, it will show on the screen. The infusion settings of the pump can be customized in a menu-driven procedure. The user can browse the rate modes provided on the start-up list; these modes are the most frequently utilized rate modes. The user can likewise utilize the option to select from saved programs, or the option to browse the list of additional standard rate modes.

After the pump has been successfully turned on, push the key to detect the syringe size and display it automatically. Ensure that the syringe size has been accurately identified. Program the delivery limit with the number or arrow keys and utilize the keys to verify the number. In the event that a delivery limit isn’t required, enter 0. Program the bolus amount with number or arrow keys and utilize the keys to verify the number. In the event that a bolus isn’t required, enter 0. Program the infusion rate with number or arrow keys, and press the keys to validate the rate.

Prior to beginning a delivery, the syringe should be primed to eliminate any residual air within the syringe tip and the infusion extension set and to remove any mechanical slack. Ensure that the infusion line is not attached to the animal when priming. Push the prime key to begin the process of priming. Leave the prime key as soon as all the air has been removed, and fluid starts to flow out of the infusion line. Now connect the catheter to the animal. Initiate the process of delivery by selecting the deliver option. Selecting the stop button will cease the process of delivery. Push and hold the power off button to turn off the pump. If the ac power is utilized, the pump will go into power-off/standby mode. In case the battery power is drained out, the pump will turn off.

A major advantage of the syringe pumps is that they can be utilized in nearly every application that involves accurate metering, particularly at the microscale and the nano-scale. They are utilized in many chemical and biomedical research areas as precise dosing procedures or to precisely administer small amounts of reagents, mix minuscule volumes, and add trace amounts of specific chemicals throughout the duration of the research experiment.

Syringe pumps can also be utilized for scale-up, developing new materials and classification of materials in chemical, pharmaceutical, catalysis, and materials science experiments. The device can additionally play a key role in reducing errors in the areas of microanalysis and instrumental analytics, for example, mass spectrometry (MS), high-performance liquid chromatography (HPLC), and liquid chromatography-mass spectrometry (LC-MS).

Continuous intravenous infusion is possibly one of the most well-known applications of the syringe pump. The syringe pump apparatus can be utilized for intermittent mouse intravenous dosing, continuous mouse infusion, intermittent rat intravenous dosing, and continuous rat infusion. The device can also be used for continuous rat infusion plus blood sampling where the researcher can catheterize two separate vessels and utilize a two-channel system to accumulate manual blood samples outside the cage without causing any stress to the animal. In addition, the apparatus can be used for GLP (Glucagon-Like Peptide-1) infusion toxicology studies.

In addition, syringe pumps that are well-suited for micro-fluidic applications are present in the market, which assists research in areas like micro-environmental control. Syringe pumps can further facilitate accurate infusion in medical and biomedical research; for example, feeding small animals or administering small doses to particular locations in the brain in neuroscience experiments. Moreover, syringe pumps are helpful for speeding up the research and reducing inaccuracies during fluid delivery in many sophisticated research fields.

Furthermore, the syringe pumps have proved themselves useful in facilitating research involving animal models and in veterinary medicine. The device is used in rodent model studies to deliver intravenous anesthetics, to deliver perioperative analgesics, to administer various drug doses for research experiments accurately, and epidural drug administration. Epidural catheters are presently utilized in veterinary medicine in special cases to give spinal analgesia (sedatives, local anesthetics). The syringe pump also facilitates the administration of fluids/ blood products to very small animals as the traditional means can risk the overdose of fluids to smaller animals. The instrument has turned out to be a valid alternative.

Strengths

The foremost strength of the syringe pumps lies in the fact that they have the ability to provide increased accuracy and precision. Also, syringe pumps are very easy to utilize. Not only does the device offer accurate drug dosing but it also requires no dilution and less wastage of the drugs.  In addition, this system permits constant infusion of fluids at a continuous rate. It is also easy to vary the infusion rate and the infusion solution.

Syringe pumps typically allow a quick setup for fluidic experiments. New pulseless syringe pumps may provide flow stability under 1%. It is also possible to know the quantity of dispensed liquid for long-term testing. The high-pressure syringe pumps can produce a maximum pressure of more than a few hundred bars and can be used in nano-fluidics even though they are not pulseless. Even if the syringe pump slows down because of high pressure, the mean flow rate of the instrument does not change with the inevitable variations in the fluidic resistance.

Additionally, the digital syringe pump can be connected with any computer or instrument with an RS-232 communications port. The device also offers digital storage of and access to dosage strategies, and remote programming. The user can easily control at least one or more than one pumps from the computer and can also alter the pumping rate, direction, and volume.

Limitations

The digital syringe pump comes with its own set of limitations. First of all, the device can prove to be slightly costly. A major drawback of the instrument is that the connection between the syringe and the animal restricts motion and is stressful for the animal. Moreover, a device is needed to avoid tangling of the catheter.

One limitation of this system is that the infusion rate or infusion solution can’t be changed for the duration of an experiment. Also, the quantity of liquid dispensed by the syringe pump is restricted in volume. Depending on the fluidic resistance and compliance, the response time of the flow rate can range from a few seconds to several hours.  On the off chance that the fluidic resistance of the instrument enhances because of channel obstruction or dust, for instance, then the pressure produced by a syringe pump increases with no limit and can result in the damaging the device.

Summary

  • A syringe pump is a type of infusion device that is used to deliver precise amounts of fluids in animals steadily.
  • The syringe pump typically consists of the pusher block, syringe holder, an internal stepper motor and an LCD touchscreen interface.
  • The device is used for continuous intravenous infusion and to accurately administer various drug doses for experiments in chemical and biomedical research.
  • The syringe pump has the benefit of increased accuracy and precision, easy utilization and connection to any computer device.
  • However, the drawback of the device is that the connection between the syringe and the animal confines movement and is stressful for the animal.

References

Harvard Apparatus. (n. d.). Choosing the Right Pump for Your Application & Budget. Retrieved from http://www.harvardapparatus.com/media/harvard/pdf/Pump%20Selection%20Guide.pdf

Abe, C., Tashiro, T., Tanaka, K., Ogihara, R., Morita, H. (2009). A novel type of implantable and programmable infusion pump for small laboratory animals. Journal of Pharmacological and Toxicological Methods, 59, 7–12. doi:10.1016/j.vascn.2008.09.002

Nolan, T. E., Klein, H. J. (2002). Methods in Vascular Infusion Biotechnology in Research with Rodents. ILAR Journal, 43(3), 175–182.

Pablo, L. S. (n. d.).  Hows and Whys of Cri Analgesia in Small Animals. Retrieved from https://www.acvs.org/files/proceedings/2011/data/papers/157.pdf

Dey, R. (2015). Syringe Pump. Retrieved from https://www.slideshare.net/biomedicz/roll-no-15-50105813

Moens, Y. (2004). Syringe Pumps for Anaesthesia/Analgesia: Toy or Tool? Retrieved from https://www.vin.com/apputil/content/defaultadv1.aspx?pId=11181&id=3852114&print=1

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