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Can IV tubing prevent backflow and contamination of the injection devices?

Can IV tubing prevent backflow and contamination of the injection devices?

Mechanism of the fluid flow in IV therapy

An IV setup comprises a drip bottle, a drip chamber, an IV tubing, and a roller clamp. Medical workers suspend the drip bottle in a stand at a height from the patient, and they connect the drip chamber into the bottle at its mouth. The roller clamp regulates the flow rate measured in drops per minute. Ultimately, the fluid in the drip chamber reaches the patient’s veins, which is made possible by the pressure difference between the drip chamber and the patient’s venous pressure. Once the volume of the liquid in the bottle goes below a certain level, however, the pressure is reversed, causing a backflow of blood into the tubing. The backflow has several adverse effects, such as blockage of the tube, loss of blood, swelling, infection, hypothermia, and blood leakage. Additionally, air embolism could happen, causing reduced cardiac output and, in extreme cases, patient death.

Current and existing prevention of backflow

To prevent backflow, medical workers use a manual method in hospitals and medical clinics wherein a blood pressure cuff is wrapped around the patient’s upper arm, and the catheter is passed beneath the cuff. Nurses and medical staff inflate the cuff when necessary, causing constriction of the lumen and thus preventing backflow. Although this method appears quite simple and has not been proven to have any adverse consequences among patients, it requires close monitoring by clinicians. Apart from backflow, IV therapy also requires a tremendous amount of effort on the part of the nurses because of the need for continuous surveillance of the patient’s status, especially in areas with scarce medical resources.

Recent methods of monitoring IV infusion

In recent years, several methods have been developed and introduced to make monitoring IV infusion easier for both patients and clinicians. These include alarm-based systems, warning systems based on RFID technology, optical detection, one-way valves, flow sensors, and wireless sensors. However, none of the aforementioned methods is equipped to prevent blood backflow.

In the above-cited monitoring methods, the system gives out an alert whenever the flow rate varies, or the level of the fluid in the reservoir falls below the desired range. Henceforth, the attention of a nurse or any health worker will be called to take action, such as to correct the problem manually.

Proposed valve-controlled locking system 

In the study of Janaki Moorthy et al. titled “An automated locking system to prevent backflow of blood in an intravenous setup” and published in the Global Journal of Researches in Engineering: J General Engineering, Volume 20, Issue 2, Version 1.0, in 2020, the engineering scientists proposed to design the valve-controlled locking system in such a way that it is both simple and cost-effective. The setup consists of a load cell, an amplifier module, a solenoid valve, and a microcontroller. The load cell determines and records the weight of the bottle and its content; the amplifier module magnifies and strengthens the signal. At the same time, the microcontroller reads and interprets the signal generated by the amplifier. Additionally and finally, the microcontroller controls the solenoid valve interfaced with it. The overall setup of the proposed system is illustrated in Figure 1.

Flowchart of the control program

Figure 1. Flowchart of the control program

Medical workers suspend the IV bottle in the load cell. The load generates tension, which correspondingly produces an electrical signal proportional to the weight of the bottle and its content. The signal is too weak to be read by the microcontroller; thus, the amplifier magnifies the signal, which the microcontroller will then read while controlling the solenoid valve built into the IV tubing to act. If the value recorded by the microcontroller is lower than the critical and cut-off point, the solenoid valve is activated and locks the tube, thus preventing the backflow.

Use of one-way valves or non-return valves

In the study of Poulomi Nandy et al. titled “Evaluation of one-way valves used in medical devices for prevention of cross-contamination,” published in the American Journal of Infection Control on March 27, 2017, the effectiveness of using one-way valves to prevent backflow of blood and contamination of injection devices was tested. They discovered the valves could withstand high back pressure levels before they finally failed. Still, they could not prevent and control the spread of infections used in medical device applications, especially if the contaminated fluid had reached the upstream side of the one-way valve. In another saying, the one-way valves could help prevent backflow for some time, but they are ineffective in controlling infections.

In the work of B. Ellger et al. titled “Non-return valves do not prevent backflow and bacterial contamination of intravenous infusions,” published in the Journal of Hospital Infection in May 2011, the authors concluded that non-return valves (NRVs), also known as one-way valves, cannot reliably prevent backflow of fluids nor serve as micro-organism filters. Thus, the research group cannot recommend the use of NRVs as a way of reducing healthcare-associated infections.

Final words on IV tubing against backflow and infections 

In the study of Subin Lee and Ketan Bulsara titled “Assessing the efficacy of commercially available filters in removing air micro-emboli in intravenous infusion systems” published in the Journal of ExtraCorporeal Technology in June 2020,  two IV sets with filters to remove air micro-emboli in the intravenous infusion system were tested. These are the GVS .2 uM and Braun Supor membrane air-eliminating filters. The two products had an efficacy rate of removing air in the infusion system at 100 and 99.8%. However, the said products were not tested for efficacy in preventing backflow and infections.

B. Braun has another product, CARESAFE IV Sets, with Optional AirStop component. The company claimed that the said product protects patients from the risks associated with air infusion and helps prevent the line from running dry. Again, preventing blood backflow and infections were not cited as the product’s advantages. Efficacy tests still need to be undertaken.     

Thus, to date, IV tubing designed and manufactured by medical device companies has never been equipped with a structure or part intended to prevent blood backflow into the tube. Design engineers attempted to solve the dual backflow problem and infections using one-way or non-return valves. However, the scientists’ work in this paper revealed that the valves could not prevent backflow or the spread of infectious complications. Thus, device engineers could not recommend the said gadgets to reduce healthcare-associated infections.

One promising endeavor is the IV tube provided with a valve-controlled locking system. In this proposal, at a certain level of remaining fluid in the IV bottle, the valve automatically locks, preventing backflow. Thus, not all the IV fluid enters the patient’s vein when the valve locks. Therefore, the remaining fluid in the IV bottle and in the tube distal to the valve may serve as a deterrent to bacterial multiplication.

An IV tube with a valve-controlled locking system could prevent backflow and the spread of infections. However, its cost-effectiveness needs to be evaluated in hospitals and medical clinics through research studies.       




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