Air embolism protecting system for safe intravenous therapy

2012 IEEE Symposium on Humanities, Science and Engineering Research Air Embolism Protecting System for Safe Intravenous Therapy *Kamran Manzoor, *Waleed Ejaz, *Najam ul Hasan, **Mustafa Arif, ***Seok Lee and *Hyung Seok Kim *Department of Information and Communication Engineering Sejong University, Seoul, Republic of Korea **Department of Computer Science National University of Computer and Emerging Sciences, Islamabad, Pakistan ***Sensor System Research Center, Korea Institute of Science and Technology, Seoul, Republic of Korea {kamran, waleedejaz, hasan}@sju.ac.kr, mustafa.arif@nu.edu.pk, slee@kist.re.kr, hyungkim@sejong.ac.kr Abstract— Intravenous (IV) therapy has been included as an integral part of nurse’s professional practice. Although it is an effective curing technique, it has some complications. Air embolism is one of such complications which may cause death of patients in some cases. In this paper, we have proposed an efficient, economic and reliable air embolism protecting system to save precious lives in case of air bubble insertion. The proposed system monitors the IV tube and when an air bubble even in fraction of millimeter gets introduced into the tube, detects it, indicates emergency and blocks the fluid flow to protect entrance of the air bubble into the human body. The proposed system has been evaluated on various IV solutions; results are very promising as the accuracy is more than or equal to 99% in every case thus supporting the implementation of the solution. Therefore, the system can be used for any type of IV solution. Keywords- Intravenous therapy; air embolism; infrared; bubble detector; flow blocker I. INTRODUCTION Intravenous (IV) therapy is the infusion of liquid substances directly into a vein. For example, parenteral nutrition is a process of feeding a person intravenously with nutritional formulas containing salts, glucose, amino acids, lipids and added vitamins bypassing the usual process of eating and digestion. “Intravenous” simply means “within a vein”. It is commonly referred as a drip because many systems of administration employ a drip chamber, which prevents air from entering the blood stream (air embolism) and allows an estimate of flow rate. Comparing with other types of curing techniques, IV therapy is an efficient way of delivering medications throughout the body. Even in some cases it becomes inevitable such as blood transfusion. Intravenous salt solutions were first used in the 1830s for the treatment of fluid loss due to cholera [1-2]. Water and salt loss were noted in the stool of cholera patients and hypertonic IV solutions were used for compensation. The results were remarkable and the mortality rate of cholera dropped from 70% to 40% [3]. Recently, research is being carried out for developing workable systems for automatically monitoring and real-time control of intravenous drip [4-6]. Today every single medical practitioner is well aware of the importance of the IV therapy. For instance, when any patient’s potassium or magnesium level gets critically low, it should be immediately balanced because a significantly low potassium and magnesium may be fatal, as it affects the human heart's activity. So IV therapy is essential for instant electrolytes replacement. Similarly in case of intense fluid loss like dehydration when the body’s inherent capabilities are no longer able of maintaining fluid or electrolyte balance, the patient requires fluid resuscitation and therefore IV therapy is the ultimate treatment. Considering its importance, IV therapy has also been included as an indispensable part of nursing course. Some complications are associated with the IV therapy: infiltration, i.e., fluid amassing in the tissue contiguous to an intravenous catheter site, phlebitis, i.e., inflammation of the vein’s wall and air embolism, i.e., the introduction of air in the intravenous fluid line which gets into the blood circulation. A little negligence of them may cause a fatal accident. In [7] intravenous infiltration detection system is discussed while [8] proposed RFID based warning system for running-out of injection fluid. In the aforementioned complications, the air embolism is considered to be the most fatal one because the death may occur if a bubble becomes lodged in the heart and stops blood flow from the right ventricle to the lungs [9]. The amount of air which can cause human being’s death is variable and depends on several factors such as body position. Air embolism into an artery is more crucial than a vein because an air bubble in an artery may directly stop flow of blood to an area fed by the artery. In the case of brain, even a bubble with a volume of just fraction of a millimeter can cause brain hemorrhage. Major causes of air embolism are: • Negligence of medical practitioner/nurse • Failure to remove air from IV tubing • Allowing solution bags to run dry • Disconnecting IV tubing • Manufacturing faulty IV tube Although the IV therapy is an effective curing technique, blood transfusion may take hours for completion. For a long time, continuous monitoring of tube for air bubble detection by any nurse or medical practitioner is practically infeasible. In this paper, we propose an automated system which monitors the IV tube, detects any little air bubble coming into the tube, This work was supported by the grant from the IT R&D program (2M28730) of the MKE (Ministry of Knowledge Economy) and the CITRC (Convergence Information Technology Research Center) support program (NIPA-2012H0401-12-1003) supervised by the NIPA (National IT Industry Promotion Agency) of the MKE. It was partially supported by Seoul R&BD Program (SS110012C0214831). Corresponding author : Hyung Seok Kim (hyungkim@sejong.ac.kr). 978-1-4673-1310-0/12/$31.00 ©2012 IEEE 1077 2012 IEEE Symposium on Humanities, Science and Engineering Research Figure 1. Block diagram of the proposed system. indicates emergency, and blocks the fluid flow to avoid entrance of the air bubble into the human body. The rest of the paper is organized as follows. Section 2 describes the proposed system in detail. Section 3 presents the experimental setup for evaluation of our proposed system and the achieved results. Section 4 concludes the paper. II. black one indicates the IR RX. There are several reasons choosing this kind of sensor: 1) this pair is very sensitive, i.e., responds promptly over sudden change; 2) very cheap; and 3) the attenuation of IR rays can be adjusted according to the density of fluid by just varying a digital potentiometer installed with the pair thus it can be used for every type of fluid. DESCRIPTION OF THE SYSTEM In the modern world, IV therapy has turned into a resilient part of medical practicing. Most of the developing countries have lack of medical/nursing staff and are not able to provide sufficient health facilities at hospitals. Due to this shortage of nursing staff, the nurse cannot perform their duties well and a little negligence in cannulating a patient can introduce air bubbles in the drip tube. Similarly, any fault in the manufacturing of drip tube can cause the formation of air bubbles although there are a number of precautions available to avoid introduction of air bubbles [10]. So our proposed methodology is an effort to save life by protecting air embolism. The proposed system should be an integral part of each IV drip stand so that operating the system requires only plugging the power switch. Once installed, it can be used for multiple times over multiple drips thus providing a cost effective solution. Although our proposed system is not too complicated to be manufactured at a low cost, it is able to solve a very crucial problem of air bubble detection in drip tube. A complete view of our proposed system is depicted in Fig. 1. Fig. 2 shows the operational functioning of our proposed system. The system consists of three main modules: bubble detector module, flow blocker module and processing module. A. Bubble Detector Module The main sensor used in our system for air bubble detection is an infrared (IR) transmitter (TX) and receiver (RX) pair as demonstrated in Fig. 3. White led indicates IR TX whereas 1078 Figure 2. Operational diagram of the proposed system (a) bubble detector module (b) flow blocker module (c) processing module. 2012 IEEE Symposium on Humanities, Science and Engineering Research On the other hand, this sensor has two main limitations. First, its range is very small and secondly, it should be aligned properly. During operation, misalignment of TX or RX may cause malfunctioning of the system. In our case, the range constraint will not affect the efficiency of the system because the drip tube thickness and diameter are not so large and the proposed design also covers the second downside of misalignment by embedding IR TX and RX in a small module. While installing a drip, IV tube will be inserted into this module, thereby maintaining line of sight between TX and RX as shown in Fig. 2(a). While working normally, i.e., when there is flow of fluid through the tube, RX gets a specific constant signal and it can be examined by the microcontroller unit (MCU) through analog to digital converter (ADC). When any air bubble even in fraction of a millimeter gets introduced in the tube, there is an abrupt change in the received signal at RX and the air bubble can be easily detected by the MCU through ADC. The major advantage of our system is “non-contact”, i.e., the sensors do not have physical contact with the flowing fluid, and instead the sensor is installed outside the drip tube. As a result of that, there will be no danger of contamination to the fluids. Figure 3. Infrared transmitter receiver pair. B. Processing Module The processing module comprises mainly MCU, ADC and emergency alert equipment. The received signal at RX is fed to the MCU via ADC. Since IR rays attenuation varies proportionally with the density of the fluid. In order to get proper signal at RX, TX voltage should automatically be varied according to the density of the fluid. Digital potentiometer is used to automate the system to adapt according to the density of the flowing fluid. It is an integrated circuit equipped with serial peripheral interface (SPI). Upon reception of digital signal, the MCU decides whether to vary the digital potentiometer or not. Hence our proposed system works for all types of fluids from simple saline solution to blood. Once an air bubble is detected in the tube, the next step is to block the flow and then alert the medical staff about this alarming situation. Even if no one is present, the proposed system can save the patient’s life by avoiding the air bubble insertion into the patient’s body. For alerting the medical staff, the most efficient and reliable way is to use IEEE 11073 protocol. This standard addresses the critical need of medical care device’s data exchange acquired at the point-of-care, in all care environments. Moreover, it also supports real-time plugand-play, interoperability of medical devices [11]. Each room may have a gateway for collecting data from each wireless transmitter embedded in the drip stand. The wireless modem embedded with the drip stand, e.g., ZigBee or Bluetooth, sends patient’s information such as bed ID, room number to the gateway. It also sends the packet for alerting once air bubble is detected. The gateway sends the alarm packet to the medical staff’s room by Ethernet or WLAN. In order to locate exact patient within a room, each bed should be equipped with an emergency light which starts glowing as an indication for danger. The proposed method is cheap and besides this, an additional functionality in the system can be provided, e.g., an emergency call to the number specified while installing the drip. Adding on this functionality further improves the efficiency and reliability of our system which in turn increases the cost of the proposed system. C. Flow Blocker Module Upon detection of the air bubble, the processing module triggers an emergency alert and also sends a signal to the flow blocker module. The flow blocker module on reception of signal immediately blocks the fluid flow thereby preventing air bubble from inserting into the patient’s body. To block the fluid flow, some expensive flow blocker devices are available in the market but we suggest a cheaper solution. The proposed flow blocker is a pair of small plastic rods operated by a micro motor. The IV tube passes between two plastic rods as shown in Fig. 2(b). One plastic rod is fixed while the other one can be moved by the motor. When air bubble is detected, MCU sends a signal to switch on the motor which in turn moves the plastic rod in such a way that the IV tube is compressed between the rods thereby stopping the flow of fluid in the IV tube. In fact, its working is same as one integrated with the IV tube for varying the speed of liquid, but the difference is its electronic controllability. So in the proposed system, the flow blocking device is efficient as well as cheaper solution. III. EXPERIMENTAL RESULTS For evaluating the proposed system, we conducted experiments several times on different IV fluids. The IV solutions are used as follows: • An hypotonic solution: 0.45% sodium chloride (1/2NS) • An isotonic solution: 5% dextrose in water (D5W) • An hypertonic solution: 5% dextrose in normal saline (D5NS) • An hypertonic solution: 5% dextrose in lactated ringer’s injection (D5LR) • Red blood cells (RBCs) • Platelets (PLTs). The experiment was conducted 400 times for each IV solution at room temperature. 200 times of the experiments among them were carried out by inserting an air bubble of 2mm3 and 1mm3 for remaining 200 times. The performance of the proposed system is measured on the basis of three metrics: 1079 2012 IEEE Symposium on Humanities, Science and Engineering Research • Probability of detection Pd: declares the presence of an air bubble when it is actually present. • Probability of misdetection Pm : declares the absence of an air bubble when it is actually present. Mathematically, Pm=1Pd. • Probability of false alarm Pf : declares the presence of an air bubble when it is actually absent. Table 1 shows the obtained experimental results. It indicates how many times an air bubble is detected among 200 times of air bubble insertion for each IV solution. In the performed experiments, Pf is entirely zero for all the IV solutions which further strengthens our argument that the proposed system is an effective solution for IV therapy. TABLE I. Evaluation of the developed system. IV solution 1/2NS D 5W D5NS D5LR RBCs PLTs 2mm3 air bubble 200 199 200 198 200 200 Fig. 5 shows Pm, which is less than 1% in all cases. For 2mm3 air bubble, Pm is zero for those IV solutions having Pd exactly 1, i.e., 1/2NS, D5NS, RBCs and PLTs while Pm is 0.5% for D5W and 1% for D5LR. For the case of 1mm3, Pm is 0 for RBCs, 0.5% for 1/2NS, D5LR and PLTs while it is 1% for D5W and D5NS. As Pm is very small for each IV solution, which is quite acceptable because air embolism can cause death if large amount of air enters into a human body in a short duration of time [12]. Therefore, our obtained results indicate towards the efficiency and reliability of the proposed system. 1mm3 air bubble 199 198 198 199 200 199 IV. Fig. 4 shows the value of Pd for each IV solution. For 2mm3 air bubble, Pd is 100% for 1/2NS, D5NS, RBCs and PLTs while it is 99.5% for D5W and 99% for D5LR. For the case of 1mm3, Pd is 100% for RBCs, 99.5% for 1/2NS, D5LR and PLTs while it is 99% for D5W and D5NS. In conclusion, it can be stated that for each IV solution Pd is approximately equals to 100% for both cases, which shows accuracy of our proposed system. CONCLUSION In this paper, we have proposed an effective, reliable and economic air embolism protecting system for saving precious human lives. The proposed system consists of three main modules. The bubble detector module is used for continuous monitoring of the IV tube for checking the presence of an air bubble. The processing module is used to alert the medical staff about the alarming situation and to trigger the flow blocker module to avoid insertion of air bubble in the human body. The proposed system is tested on various IV solutions under similar atmospheric conditions and the results are remarkable as the accuracy is more than or equal to 99% for every case. With our proposed methodology, the IV therapy will get enhanced and chances of fatal accidents will reduce significantly. The modified version of the proposed system with more sophisticated sensors like ultrasonic, can also be utilized as air detectors in other industries such as pharmaceutical industry, the foodstuffs industry, automation technology and mechanical/hydraulic engineering during the manufacturing of machinery and devices because in these industries a small air bubble can cause malfunctioning of the device. REFERENCES [1] Figure 4. Probability of air bubble detection for various IV solutions. [2] [3] [4] [5] [6] [7] Figure 5. Probability of misdetection for various IV solutions. 1080 T. Latta, “Malignant cholera relative to the treatment of cholera by copious injection of aqueous and saline fluids into the veins,” Documents communicated by the Central Board of Health, London, Lancet, vol. 2, no. 274, pp. 1831-1832. S. Awad, S. P. Allison, and D. N. Lobo, “The history of 0.9% saline,” Clinical Nutrition, vol. 27, no. 2, pp. 179-188, 2008. L. G. Richard, A. C. Benedito, and A. D. Rebecca, “Cholera, Diarrhea, and Oral Rehydration Therapy: Triumph and Indictment,” Clinical Infectious Diseases, vol. 37, no. 3, pp. 398–405, 2003. A. Cataldo, G. Cannazza, N. Giaquinto, A. Trotta, and G. Andria, “Microwave TDR for Real-Time Control of Intravenous Drip Infusions,” IEEE Trans. Instrum. Meas. vol.PP, no.99, pp.1-8, 2012. P. Bustamante, U. Bilbao, N. Guarretxena, and G. Solas, “Wireless Sensor for Intravenous Dripping Detection Electronics,” in Proc. IEEE Int. Conf. on Circuits and Systems (ICECS), pp. 399 – 402, 2007. H. Ogawa, H. Maki, S. Tsukamoto, Y. Yonezawa, H. Amano, and M. Caldwell, “A new drip infusion solution monitoring system with a freeflow detection function,” in Proc. IEEE Engineering in Medicine and Biology Society (EMB), pp. 1214 - 1217, 2010. M. S. Alley, W. J. Naramore, N. Chou, and L. W. Winchester, “Wireless application in intravenous infiltration detection system,” in Proc. IEEE Engineering in Medicine and Biology Society (EMB), pp. 977 - 980, 2008. 2012 IEEE Symposium on Humanities, Science and Engineering Research [8] C. Huang, and J. Lin, “A warning system based on the RFID technology for running-out of injection fluid,” in Proc. IEEE Engineering in Medicine and Biology Society (EMB), pp. 2212 - 2215, 2011. [9] L. C. O'Dowd, and M. A. Kelley, “Air Embolism,” Chinese Medical Biotechnology Information Network, Retrieved Jan. 2012. [10] J. W. Weaver, “Removing Air Bubbles Prior to Drip Infusion Cholangiography,” Radiology, vol. 146, no. 1, pp. 230, 1983. [11] ISO/IEEE 11073-10201 Health informatics – Point-of-care medical device communication – Part 10201: Domain information model, Institute of Electrical and Electronics Engineers Standards Association, Manager, Standards Intellectual Property, 444 Hoes Lane, Piscataway, NJ 08854. [12] J. J. Prag, “Sudden death due to air embolism,” South African Medical Journal, pp. 566-569, 1951. 1081