Lymph Flow Measured during Lympedema Supermicrosurgery
Transonic Flowsensor Detects Cerebrospinal Fluid (CSF) Shunt Malfunction
Hydrocephalus, derived from the Greek words hydro meaning water and cephalus meaning head, is the abnormal accumulation of cerebrospinal fluid (CSF) within the ventricles of the brain. It afflicts over 1,000,000 persons in the United States ranging from infants and older children to young, middle-aged and older adults. Hydrocephalus occurs when there is an imbalance between the amount of CSF that is produced and the rate at which it is absorbed. As the CSF builds up, it causes the ventricles to enlarge and the pressure inside the head to increase which leads to serious consequences.1
Currently, there is no way to prevent or cure hydrocephalus. The most common treatment—and the most common procedure performed by pediatric neurosurgeons in the United States—is the surgical implantation of a device called a shunt, a flexible tube that placed into the ventricular system of the brain which diverts the flow of CSF into another region of the body, most often the abdominal cavity, where it can be absorbed. A valve within the shunt maintains CSF at normal pressure within the ventricles.
However, a shunt system frequently fails or malfunctions. An estimated 50% of shunts in the pediatric population fail within two years of placement and repeated neurosurgical operations are often required. The most common shunt complication is mechanical malfunction or shunt blockage than occurs in between 8% and 64% of shunts.2 When a blockage occurs, CSF accumulates and can result in symptoms of untreated hydrocephalus. Annually, shunt malfunction accounts for roughly 39,000 admissions and as many as 433,000 hospital days for pediatric HCP alone. The annual burden for HCP-related shunts ranges from $1.4 to $2 billion per year, and nearly half of these expenses go toward the revision of malfunctioning systems.3 With the lack of any sensor that could detect a shunt malfunction immediately, the clinician would have to perform several tests that could increase radiation exposure to patients and create other complications. Moreover, the specific reason for mechanical failure—absent, excessive, or inadequate CSF flow—would often elude the clinician.
Now there is a noninvasive, accurate Flowsensor that can detect mechanical shunt malfunction. A 2015 study, published in the Journal of Neurosurgery, evaluated an ultrasonic transit time flow sensor in five pediatric and 11 adult patients with external ventricular drains (EVDs).4 The study demonstrated that the Transonic Flowsensor accurately measures CSF output within ± 15% or ± 2 ml/hr, diagnoses the blockage or lack of flow, and records real-time continuous flow data in patients with EVDs. The authors concluded that the sensor's clinical applications may be of particular importance to the noninvasive diagnosis of shunt malfunctions with the development of an implantable device.
Maastricht Hospital Neonatology Researchers Measure Chorioallantoic Arterial Blood Flow in Chick Embryos
Chorioallantoic artery blood flow in avian species correlates with umbilical blood flow in mammals. Chorioallantoic artery blood flow and heart rate were studied in the 100 chick embryos from stage 34 until stage 43 with extends from days 9 to day 16 of a 21-day incubation period.
Eggs were opened at the air cell and placed in a small temperature and humidity controlled plexiglass box with a continuous gas flow of a N2/O2 mixture (5 L/min). The chorioallantoic artery was identified near the fetal abdomen and a 0.5 mm Transonic V Flowprobe was applied to the artery to measure flow. The heart rate was derived from the blood flow signal.
Mean blood flow rose from 0.35 mL/min at stage 34 to 3.13 mL/min at stage 43 which correlated with an increase in body weight from 1.51 to 15 grams during the same period. Heart rate increased from 195 to 289 beats/min during the same time period. The study lead to a follow-up study that examined the effect of hypoxia on chorioallantoic blood flow and heart rate in 140 chick embryos. Flowprobes were used to measure peak flow and blood flow acceleration in addition to measuring chorioallantois arterial flow and heart rate.
Telemetry Abstracts Draw Interest at Experimental Biology 2015
EndoGear telemetry drew healthy interest at this year's largest US research conference, Experimental Biology. Three EndoGear telemetry abstracts were presented. One, authored by Armon Davtyan from Transonic Endogear, Davis CA, reported on the development of a wireless power source for implantable telemetry devices to provide power for telemetry monitoring over extended periods of time. The Wireless Power Supply (WPS) uses inductive power technology to send power to an implanted 3-dimentional Wireless Power Receiver (WPR) that is used instead of the battery to provide continuous power to a telemetry system used in small animals such as rats.
A second EndoGear abstract, authored by Andreas Michaelides of Nicosia, Cyprus, reported on the development of remotely activated thrombus formation in the common carotid artery of awake rats as a model for studying the effects of thrombolytic and antithrombogenic agents on cerebral circulation. Rather than rely on mechanical occlusion that would lead to a gradual carotid occlusion, but requires additional surgery, the researchers developed a miniature cuff electrode (0.8mm ID) that could be used with an implantable Endogear telemetry system to induce a thrombus in the carotid arteries of awake rats. The telemetry system is capable of bidirectional user control and it can supply an excitation current to the cuff electrode to induce the thrombus formation at a user defined time interval after surgery.
Portal Vein Blood Flow Measurement during Auto Islet Cell Transplantation
Excising a diseased pancreas removes not only pancreatic cells that produce digestive enzymes but also islet of Langerhans cells that produce insulin to control blood sugar. Without insulin a patient becomes diabetic and requires lifelong use of supplemental insulin to control blood sugars. Auto islet cell transplantation takes islet of Langerhans cells from the pancreas and transplants them to the liver to reduce the diabetic risk. The removed pancreas is processed to isolate the insulin-producing islets of Langerhans cells. The isolated cells are suspended in a solution and then 800 - 1500 cc of solution is slowly infused through the splenic vein back into the liver through the portal vein where it is hoped that they will implant, grow and produce insulin to metabolize sugar.
Flow Measurement during Islet Infusion
Surgeons measure portal venous flow during islet cell infusion to detect any sudden decrease in flow that may foreshadow a problem with the infusion. A 10 mm to 14 mm Perivascular Flowprobe is placed on the portal vein and flow is measured continuously. In this high stakes auto islet cell transplantation procedure, Transonic® Flowprobes provide a continuous volumetric measure of portal vein flow to inform the surgeon about the safety, fluidity and success of auto islet cell transplantation.
More more information check out the Portal Vein Blood Flow Measurement during Islet Cell Transplantation Medical Note.
Beyond Blood: Why Not Snake Venom Flow?
Transonic might be known for blood flow measurements, but blood isn’t the only fluid flowing in the body, especially if that body is a rattlesnake. When rattlesnakes bite, they can control whether or not to release any venom. The question then comes, how much control do Rattlesnakes have over their venom release, and how and when does that venom flow during a strike?
Dr. Bruce Young of Lafayette College explored those questions in “Venom flow in rattlesnakes: mechanics and metering” published in The Journal of Experimental Biology, 2001.
Transonic Perivascular Flowprobes were chronically implanted on the right venom duct of four diamondback rattlesnakes to measure to flow during defensive and predatory strikes. Venom flow measurements during strikes were synced with high-speed video recording to determine how the flow of venom compared to the timing and duration of the strike penetration. A total of sixty strikes were measured providing new insights into the mechanics of snake venom flow:
- There is a period of retrograde (reverse) flow at the end of venom injection.
- Duration of venom flow is significantly less than the duration of penetration.
- Defensive strikes resulted in more total venom released at a much faster flow rate than predatory strikes.
- When only one fang strikes, venom will flow through the venom duct of the opposite fang but not exit the orifice.
With the help of Transonic technology and a creative perspective on what it means to measure flow, it is possible to tackle many novel questions. Dr. Young was able to measure venom flow through the ducts of rattlesnakes when they strike, what could you measure?
Young BA, Zahn K. “Venom flow in rattlesnakes: mechanics and metering” J Exp Biol. 2001Dec; 204 (pt 24): 4343-51.
Transonic in Space: Surgery in Zero-G
The zero gravity environment of space presents astronauts with many challenges. What are simple tasks on earth become carefully choreographed maneuvers in space. Added to that is the limited access to resources. So what happens when you have to perform a complicated and delicate task like emergency surgery?
While cruising a couple hundred miles above the earth in the ISS it is possible to make an emergency trip back to earth. That option is not viable for extended space flights. To that end, Dr. George Pantalos of the University of Lousville’s Cardiovascular Innovation Institute is developing the technology to make “astro surgery” possible.
lood, like all fluids in space, forms floating droplets that drift everywhere if not contained. This means that all surgical fields need to be fully contained and controlled. To that end, Dr. Pantalos developed an airtight, watertight surgical container that is secured over the surgical field and pumped full of saline to control bleeding. Transonic tubing flow measurements are used to monitor the flow of saline into the surgical structure. Ports in the surgical container would allow for access to the site for a laparoscopic-type procedure. Dr. Pantalos’s team has tested their design on several trips in NASA’s zero-gravity jet with great success.
Check out the report by Research Minute: