Longtime Transonic Collaborator George Pantalos Flies Again with Team Performing Space-Age Research
Longtime Transonic Collaborator George Pantalos is heading up a team from the University of Louisville to investigate what it would take to provide surgical treatment for an ill or injured astronaut during a trip to Mars or when living in a Lunar colony. The team made their first test flight in a NASA C-9B aircraft in September and now are scheduled for another flight at the beginning of December.
Low or zero gravity makes it more difficult to use surgical instruments, perform surgical tasks, and handle medical fluids and waste material. Their experiment 49-P is a collaboration between the University of Louisville and Carnegie Mellon University to develop new ways of using existing medical instruments and customizing other surgical devices in order to conduct surgical tasks successfully and demonstrate ways to control and stop bleeding in 0-G and Lunar-G.
A modified Transonic tubing flowmeter module and clamp-on flowsensor were integral to the Astro-surgery set-up to manage flow rates of 30 ml/min for efficient control and containment of simulated blood, debris and protein waste fluids in the surgical dome under weightless conditions.
Cardiovascular space explorer Pantolos writes, “We are developing surgical capabilities for exploration and colonization space flight. Consequently, we needed to evaluate these surgical tasks both in 0-G and in Lunar-G . The flight profile provided seven 0-G parabolas followed by three Lunar-G parabolas for each set of 10 parabolas flown. This worked out very well for our testing. The quality and duration of the 0-G and Lunar-G periods was very good and the flight crew was very responsive to our needs. It was a treat to be flying back in the high-quality environment of the NASA C-9B aircraft and I highly recommend that NASA continue with this capability to support research for exploration and colonization spaceflight.”
Pantalos reported that the overall test objectives of Experiment 49-P were to test several aspects of conducting surgical procedures in the reduced gravity environment of spaceflight. Specifically, in 0-G and Lunar-G they tested
- the ability of rigid and flexible containment domes to provide hemostatis and clear the dome of blood by purging with irrigation fluid,
- the ability of an automatic control system to fill and empty a surgical containment dome with irrigation fluid without bubbles,
- the ability of a sequential filtering system to process surgical wound waste fluid for reclamation of water,
- the ability to effectively apply a surgical drape to skin,
- the ability for endoscopic surgical tools to function adequately, and
- the ability to pass suture, tie surgical knots, and to suture and staple an incision closed.
Pantalos reported that during the 49-P Sept 2015 flight campaign they achieved all test objectives and made key observations on how to improve each of these surgical tasks.
To view more about the 49-P Sept 2015 flight campaign see:
Human Supermicrosurgery: First Report of Measuring Lymph Flow in Humans with Transit-time Ultrasound
The flow measurements were astondishing:
- Lymph vessel 1 @ 0.54 mL/min;
- Lymph vessel 2 @ 0.78 mL/min;
- Lymph vessel 3 @ 0.78 mL/min;
Supermicrosurgery performed by surgeons such as Dr. Chen (Univ. of Iowa) involves the sewing of lymphatic ducts to veins to mitigate the effects of lymphedema. In the first published report of measuring lymph flow directly in humans, Dr. Chen reports in the 2015 Journal of Plastic, Reconstructive and Aesthetic Surgery, that it is important to select healthy, functioning lymphatic vessels when performing this supermicrosurgery. Previously, surgeons had to rely on visually observing the blood “wash out” of a vein to decide if a lymphedema anastomosis was patent. Now they have Transonic quantitative flow measurements to help them decide the optimum conduit.
After using a Transonic 0.7 Microsurgical Flowprobe with the AureFlo® to measure lymphatic flow before and after an anastomosis in 29 lymphatic vessels, Dr. Chen concluded that transit-time ultrasound technology (TTUT), with its sensitivity reaching 0.01 mL/min), offers promise for:
- guiding lymphatic vessel selection;
- confirming anastomotic patency;
- not having to rely on “wash out” alone to make surgical decisions.
For full communication see: Chen WF, Zhao H, “Transit-time ultrasound technology-assisted lymphatic supermicrosurgery,” J Plast Reconstr Aesthet Surg. 2015; 68(11): 1627-8. (Transonic Reference # 10651AH)
Release of Updated Hemodialysis Handbook Celebrates 20 Years of Access Flow Measurement with the Krivitski’s Method
Nikolai Krivistki Ph.D., D.Sc.
Aha Moment Sparks Genesis of the Hemodialysis Monitor
In 1991, Biomedical Engineer Nikolai Krivistki Ph.D., D.Sc., came to the United States from Russia. He had previously worked at the ICU and Hemodialysis Units of Moscow USSR Medical Academy’s National Research Center for Surgery. During his first several months at Transonic Systems, he familiarized himself with Transonic products, especially its proprietary clamp-on tubing flowsensors and dedicated tubing flowmeter. Suddenly, he had an “Aha” moment. He envisioned how existing transit-time ultrasound technology could be combined with classical indicator dilution technology to provide a superior flow measurement. He termed his innovation “ultrasound indicator dilution” technology.
As he considered real-life blood flow measurement problems reported by nephrologists such as Dr. Thomas Depner and Dr. Jeffrey Sands, Nikolai had another “aha” insight. He realized that vascular access flow could be measured directly with ultrasound dilution technology by simply reversing the dialysis blood lines and injecting saline into the venous line. The first patents of the “Krivitski Method” were filed in the fall of 1994. Indicator dilution measurements soon revolutionized hemodialysis. Until then, access flow could not be directly measured. The measurements took off like a storm because it gave clinicians information they needed about the adequacy of dialysis and what is the actual flow through a vascular access. Within a few short years, ultrasound indicator dilution technology was recognized in the Guidelines of the American Kidney Foundation as the gold standard, or the technology with which other measurement technologies should be compared.
Awards followed including, in 2000, the prestigious US Small Business Administration’s Tibbets Award for Research and Innovation which was presented to Transonic at a White House breakfast ceremony. The new indicator dilution technology also spurred an avalanche of publications that reported on the value of access flow measurements in assessing hemodialysis effectiveness and predicting the advent of a stenosis within an access. Since then, the measurements made possible by Dr. Krivitski’s aha insights have become the cornerstone of many vascular access measurement programs.
Cardiac Health, the Next Challenge in Hemodialysis Care
“The ability to monitor cardiac output is one of the important cornerstones of hemodynamic assessment ...in particular in patients with
pre-existing cardiovascular comorbidities.” Tucker T et al
Vascular access surveillance is well accepted for proactive hemodialysis care. Now, cardiovascular monitoring is the next challenge in quality hemodialysis care, particularly since cardiovascular disease (CVD) is the leading cause of morbidity and mortality in patients with End-Stage Renal Disease (ESRD). It accounts for half of the deaths and one-third of hospitalizations of dialysis patients. In addition, cardiovascular collapse is a major cause of complications during hemodialysis treatments. Congestive heart failure (CHF) in ESRD patients results from cardiac overload, anemia, severe hypertension and cardiac dysfunction. CVD mortality rates are approximately 30 times that of the general population, and in adolescents, CVD mortality rates are over 1,000 times that of their age-related peers. These statistics are alarming.They are forcing proactive cardiovascular management of dialysis patients.
“Hemodynamic stability is threatened and often severely compromised by hemo-dialysis largely because of the obligate fluid removal during a short time span.”
Thomas Depner, MD, noted that the rapid removal of large volumes of fluid during hemodialysis severely tests the limits of a patient’s cardiac function. Just as a treadmill stress test stresses a heart’s response to exercise, cardiac output measurements during hemodialysis monitor a heart’s response to fluid removal during the dialysis treatment. Because cardiovascular parameters can change dramatically during dialysis, multiple cardiac measurements are advised during a dialysis session in order to assess a patient’s clinical condition.
While access flow remains fairly constant during a hemodialysis treatment, cardiac output decreases an average of 20% during the treatment causing less blood flow to be available to sustain the body’s vital functions. A healthy body will respond to this by increasing peripheral resistance to sustain the blood supply to the heart and brain.
Cardiovascular monitoring has now been incorporated into the comprehensive protocol for hemodialysis surveillance with the Transonic HD03 Monitor.
Venous Pressure is Not a Surrogate for Flow
Venous pressure monitoring has been advocated to detect early signs of vascular thrombosis. Even before Dr. Spergel’s landmark 2004 publication “Static intra-access pressure ratio does not correlate with access blood flow,” a Cleveland Clinic nephrologist DH Chand et al published a paper in Pediatric Nephrology entitled, “Venous Pressure Monitoring Does Not Accurately Predict Access Failure in Children.”
The publication reports the findings of clinicians who analyzed 335 venous pressure measurements from ten children with either an AV fistula or graft at Cincinnati Children’s Hospital Medical Center. Eighteen access thromboses were identified in five patients with AV grafts in whom a total of 241 venous pressures were measured. The clinicians found no correlation between specific thrombotic events and mean venous pressures. They concluded that dynamic pressure monitoring is not an adequate predictor of thrombosis in pediatric patients.
Chand DH, Poe SA, Strife CF, “Venous pressure monitoring does not accurately predict access failure in children,” Pediatr Nephrol. 2002; 17(9): 765-9.
Spergel LM, Holland JE, Fadem SZ, McAllister CJ, Peacock EJ, “Static intra-access pressure ratio does not correlate with access blood flow,” Kidney Int. 2004 Oct;66(4):1512-6.
Two YouTube Videos Showcase Intraoperative Cerebrovascular Flow Measurement during Aneurysm Clipping Surgery
Two YouTube videos demonstrate Dr. Fady Charbel’s (University of Illinois at Chicago) skillful microsurgical clipping of cerebral aneurysms.1,2 The first video features the clipping of three aneurysms: a left middle cerebral artery (MCA) aneurysm-(B) performed through a modified right lateral supraorbital craniotomy, a previously coiled anterior communicating (ACOM) artery aneurysm-(C) and a bilobed right MCA aneurysm-(A). First, the left MCA aneurysm is identified and clipped. Then shown is the final clipping of the ACOM aneurysm following multiple clip repositionings based on Transonic flow measurements. Finally, the right MCA aneurysm is then identified and each lobe is clipped separately.
The second YouTube video, entitled “Clipping of a ruptured anterior communicating artery aneurysm with right A1-A2 sectioning and reanastomosis,” demonstrates the microsurgical clipping of a previously coiled and ruptured anterior communicating artery aneurysm. The video shows an end-to-end anastomosis of the right A1-A2 that allowed for complete obliteration of the aneurysm while preserving the flow in all four vessels.
1Hage ZA, Charbel FT, “Clipping of bilateral MCA aneurysms and a coiled ACOM aneurysm through a modified lateral supraorbital craniotomy.” Neurosurg Focus. 2015 Jan;38(VideoSuppl1):Video19.
2Hage ZA, Charbel FT, “Clipping of a ruptured anterior communicating artery aneurysm with right A1-A2 sectioning and reanastomosis,” Neurosurg Focus. 2015 Jul;39 Video Suppl 1:V10.
VIEW VIDEOS AT:
Surgical Training Workshops Uses Transonic Flow As Assessment Tool
Transonic intraoperative flow measurements have been long used as an assessment tool during workshops designed to train researchers to sew minute anastomoses in rodent vessels. During the past decade, flow measurements have been incorporated into cerebrovascular surgical workshops that allow neurosurgeons to practice their sewing skills in constructing cerebrovascular bypasses. Now, several microsurgical workshops have also adopted Transonic flow measurement as an assessment tool and in September, a Thoracic Society Directors Association Surgical Residents’ Boot Camp at the University of North Carolina, used Transonic flow measurements as part of their training curriculum.
The training session was designed for first-year cardiothoracic residents to understand and practice techniques needed during surgery. A porcine model was used for initial training and a basis for ongoing practice for coronary and vascular anastomosis skills. The Transonic Graft Patency Protocol Graft and graft assessment using Transonic Flowprobes was included in the syllabus for the course.
In tandem with the North Carolina Boot Camp workshop, a new technical note was produced to promote use of flow measurement as an assessment tool during surgical training workshops. This note is derived from Transonic’s history of having surgical training workshops use our transit-time ultrasound flowprobes to verify the patency of a newly sewn anastomosis by workshop students and/or test the surgical proficiency of a workshop participant.
By measuring volume flow with a transit-time ultrasound flowprobe, students, whether they are surgical residents learning the skill for the first time, or fellows or surgeons perfecting their sewing skills, can tell immediately if the anastomosis exhibits technical error. The trainer/director then has an opportunity to assess the progress of students during the workshop’s course.
Check Out “Sensing Savvy” — Our New Transonic Blog Site
In September, Transonic launched its new blog “Sensing Savvy” on www.transonic.com. The blog navigation button will be right at the top of the screen in the blue header. Clicking the button will take you to the blog itself. Already, more than 20 cardiovascular and hemodialysis blogs have been posted to attract surgeons, nephrologists, and hospital/clinic administrators to our website. In the future the topics of the Sensing Savvy blogs will expand to include applications such as cerebrovascular and research.
Examples of posted blogs include:
- Aha Moments Spark Genesis of the Hemodialysis Monitor
- Have You Ever Heard of FlowSound Audiovisual Graft Patency Assessment?
- Hemodialysis Vascular Access Monitoring: A Medical Imperative
- Cardiovascular Disease - An ESRD Epidemic
- Technologies that Could Save Your Hospital Money and Improve Patient Outcomes
- Analysis of a Bypass Graft Waveform: 5 Things to Look For
- The Vascular Access - The Achilles Heel of Hemodialysis
- Improving Post-CABG Patient Outcomes With Intraoperative Transit-time Flowmetry
- Don’t Depend on Pulsatility Index as a Sole Indicator of Graft Patency
In conjunction with the Sensing Savvy blog postings, we are also releasing to the media two ebooks targeted to the cardiothoracic surgeon. The first is: Tales from the OR: How a Leading Surgical Team Improved CABG Outcomes. The second ebook to be released, is Flow Measurements Interpretation.