Historic Harlem Hospital Delivers Exceptional Hemodialysis Care
Harlem Hospital Center, located between 136th and 137th Streets on Lenox Ave. in New York City, has been serving its Harlem neighborhood for over 125 years. Not only has the hospital had a long and respected reputation as the training ground for minority health professionals, but it is also credited with saving the life of Martin Luther King, Jr. in 1958 after he was stabbed by a deranged woman when he was delivering a speech at a nearby bookstore.
Hemodialysis Surveillance Pioneer
Similarly, the hemodialysis unit at the hospital has a long history with Transonic’s flow-based hemodialysis surveillance program. For the past 20 years Harlem Hospital has used Transonic flow-based surveillance as part of their standard of care for their hemodialysis patients.
In 1996, shortly after the launch of Transonic’s first Hemodialysis Monitor, Hemodialysis Specialist Lynn Cook trained the Harlem Hospital staff on using the first HD01 Hemodialysis Monitor to measure delivered blood flow, recirculation and vascular access flow. The hospital later upgraded to an HD02 to perform the same measurements. Most recently, the hemodialysis clinic’s staff was in-serviced on their new HD03 Hemodialysis Monitor. The routine delivered blood flow, recirculation and vascular access measurements will be augmented with cardiac output measurements to evaluate a patient’s heart function while he or she is undergoing hemodialysis.
Caring and Compassionate Team
Lynn reports that the 80-patient clinic’s nurses and staff, under the direction of Dr. Leroy Herbert, Hemodialysis Medical Director and Dr. Jeffrey Wallach, Chief, Division of Nephrology are an incredibly caring and compassionate team that all work together to ensure that their patients get the best standard of care possible. The hospital’s high performance in nephrology, that includes Transonic Hemodialysis Protocols in the routine surveillance of their patients, was recognized by U.S. News & World Report in 2013-14.
Best Practices in Hemodialysis Handbook
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Reversed Bypass Flow Linked to Left Subclavian Artery Stenosis
Dr. Matija Jelenc and his collaborators at the University Medical Centre Ljubljana, Slovenia reported on an unusual case where a left subclavian stenosis caused a reversal in flow in a left internal mammary artery to left anterior descending artery (LIMA-LAD) graft during systole.
A 62-year-old male patient with a history of hypertension and hypercholesterolemia presented with worsening chest pain. Preoperative angiography showed narrowing in the left main coronary (LCA) and left anterior descending (LAD) arteries. His right coronary artery (RCA) show an 80% stenoses. Echocardiography indicated a normal ejection fraction and no valvular pathology and his right carotid artery had been stented.
Off-pump coronary artery revascularization was performed. The left internal thoracic artery (LITA) was anastomosed to the left anterior descending artery (LIMA-LAD). Saphenous vein grafts were anastomosed to the intermediate artery and the first and second obtuse marginals, respectively from the right internal thoracic artery (RITA) because the aorta was found to be heavily calcified. During construction of the distal anastomoses to the obtuse marginals, radial arterial pressure suddenly dropped to 39/25 (31) mmHg. The left hand turned pale and no pulse was found.
A femoral artery catheter was placed for pressure monitoring and comparison with radial arterial pressure. Left femoral artery pressure was 110/35 (52 mmHg). The anastomoses to the obtuse marginals were completed as planned.
When the transit-time ultrasound Flowprobe was placed on the LIMA-LAD bypass graft, Intraoperative transit-time graft flow measurement showed reversal of LITA flow during systole and lower than expected flow during diastole that supplied the myocardium. The surgery was completed and the patient was closed.
Although there were no signs of myocardial ischemia, the patient’s left hand remained cold and without a pulse. On the third day postop, an angiogram showed a subtotal stenosis of the proximal left subclavian artery. The proximal left subclavian artery was dilated and stented with two Protégé stents. The further postoperative course was uneventful and the patient was discharged on the 12th postoperative day.
The surgeons acknowledged that had they known of the subclavian stenosis prior to creating the LIMA-LADS bypass, they would have chosen another revascularization strategy. They noted that the presence of the highly calcified aorta and proximal brachiocephalic trunk would suggest that the subclavian would also be calcified. Fortunately, the reversal in flow in the graft occurred only during systole. During diastole, there was positive flow to the myocardium.
Generally, when transit-time ultrasound flow measurements indicate reversed flow in a graft, one thinks of competitive flow from a native coronary that is not completely stenosed. In this case, it was caused by a subclavian stenosis, a rare, but not to be overlooked event.
Jelenc M, Knezevic I, Stankovic M, Gersak B, “Intraoperative left subclavian artery occlusion with left hand ischaemia and steal syndrome in the left internal thoracic artery,” Interact Cardiovasc Thorac Surg. 2012 Oct;15(4):772-3. (Transonic Reference # 10794AHM) Call to Action:
Transit-Time Flowmetry Guides Arteriovenous Malformation Resection Surgery
In a landmark study, Dr. Alessandro Della Puppa and his colleagues at Padua University Hospital chronicled their use of the Charbel Micro Flowprobe® during surgery for brain arteriovenous malformations (BAVMs). Their aim was to test the feasibility and reliability of using intraoperative blood flow measurements to minimize possible ischemic complications and thereby improve the clinical outcomes of their patients. This was the first systematic study on the use of the Charbel Flowprobe in this application. The study included a retrospective analysis of data from 25 patients with brain AVMs who consecutively underwent microsurgical resection with the assistance of flow measurement. Flow measurements were performed 203 times on 92 vessels including arterial feeders, potential transit arteries, and venous drainages of AVMs during different phases of AVM resection.
The clinicians found that flow data helped them to understand the AVM architecture and guide surgical planning and AVM resection. Flow data completely agreed with ICG-VA-derived angioarchitecture of AVMs. In seven cases, flow measurements clarified ICG-VA data for planning the surgical approach. Flowmetry was able to discriminate between deep small arterial feeders and venous drainages (76% of cases, 19/25) both superficially and deeply located, by defining the direction of flow in AVM vessels.
Flow measurements also identified transit arteries in 12% of cases (3/25) by detecting a major flow drop between 2 points of the same vessel during AVM dissection. Further dissection revealed a deep afferent artery to the nidus arising from a transit artery between the points of the two previous measurements. At the final stage of resection, a residual nidus was detected in 20% of patients (5/25) when the flow value of venous drainage was greater than 4 mL/min.
They concluded that intraoperative flow measurements were feasible, safe, repeatable, and reliable in assisting surgery in different phases of AVM resection. Intraoperative data changed surgical planning in 32% of cases: 12% sparing a transit artery and 20% of further final dissection of the AVM nidus before sectioning the main venous drainage.
Della Puppa A, Rustemi O, Scienza R, ìIntraoperative Flow Measurement by Microflow Probe During Surgery for Brain Arteriovenous Malformations,î Neurosurg 2015; Jun;11 Suppl 2:268-73. (Transonic Reference # 10288AH)
Kirk HJ, Rao PJ, Seow K, Fuller J, Chandran N, Khurana VG, “Intra-operative transit time flowmetry reduces the risk of ischemic neurological deficits in neurosurgery.” Br J Neurosurg. 2009 Feb;23(1):40-7.
Dr. Della Puppa’s work has been supported, in part, by Iatrotek, Transonic’s Italian distributor for Neurosurgical products.
AVM Resection: Flow-Assisted Surgical Technique (FAST)
AVM Case Report: Residual AVM Nidus Detected by Intraoperative Flowmetry
AVM Case Report: Transit Artery Identified by Intraoperative Flowmetry
Pub Brief: (Della Puppa 2015): Intraoperative Flow Measurement by Microflow Probe During Surgery for Brain Arteriovenous Malformations
The Role of Intraoperative Perfusion Assessment
In the February 2016 issue of Plastic and Reconstructive Surgery, Dr. B.T. Phillips from the Division of Plastic, Maxillofacial, and Oral Surgery, Duke University along with other surgeons from prominent centers published a review that outlines the intraoperative technologies that that help them interpret information to enhance their surgical decision-making.
The technologies summarized in the review include various dye-based and non-dye-based near-infrared angiography and tissue oximetry measurements, and ultrasound-based tools. Available literature for the individual devices and supporting evidence for their use are discussed. One hundred three references are included. The authors recommend the evidence-based use of these tools in indicated surgical cases to improve clinical outcomes. Of particular note is the inclusion of transit-time ultrasound technology in the review. Non- Doppler based ultrasound technologies such as transit-time ultrasound and microvascular ultrasound with microspheres are distinguished from the familiar Doppler-based ultrasound technologies (hand-held Doppler and Color-duplex ultrasound). It is also the first publication that cites use of the AureFlo® in microvascular surgery.
Phillips BT, Munabi NC, Roeder RA, Ascherman JA, Guo L, Zenn MR, “The Role of Intraoperative Perfusion Assessment: “What Is the Current State and How Can I Use It in My Practice?” Plast Reconstr Surg. 2016 Feb;137(2):731-41. (Transonic Reference # CV10792AHR)
Transit-Time Ultrasound Volume Flow (mL/min) Is Not the Same as Doppler Velocity (mm/sec)
For more than 30 years, transit-time ultrasound technology has been universally recognized as the gold standard for direct measurement of absolute volume flow. Developed at Cornell University by Transonic founder Cornelis Drost, the technology overcame the problems inherent with earlier electromagnetic flowmeters and quickly became the tool used by researchers and clinicians alike. Transit-time ultrasound technology has now been cited in more than 4,000 publications.
- TTU Directly Measures Volume Flow, Not Velocity: Wide beam ultrasonic illumination of transit-time ultrasound flowprobes measures velocity of fluid across the entire band width of graft/vessel to derive volume flow. Doppler derives flow from separate estimates of average velocity across a chord or inside vessel cross-sectional area.
- TTU Measures Flow in All Fluids: TTU flow measurement is not dependent on particulate matter in the fluid (i.e. RBCs), as with Doppler. Measurements can be made in arteries, veins, and even lymph vessels.
- TTU Is Insensitive to Misalignment of Probe on Vessel. The transit-time ultrasound flowprobe and reflector design compensates for misalignment of a vessel within the flow sensing window of the probe. Doppler misalignment with the vessel can produce serious inaccuracy in measurement.
Measurement of Cardiac Index in Hemodialysis Patients
At Berlin’s 2015 Nephrology Congress, Stephanie Haag and colleagues from the University Hospital Tübingen and the Nephrological Center, Leonberg, Germany, reported about their measurements of cardiac index in hemodialysis patients with the Transonic HD03 Monitor.
Their hypothesis was that measuring the cardiac index using ultrasound dilution during hemodialysis (HD) can be used to detect patients with excessive access flow and cardiac impairment. They used a prospective cross-sectional study to measure cardiac output (CO), cardiac index (CI) and access flow (AF) with the Transonic HD03 Monitor at the beginning and end of hemodialysis sessions in 185 patients (35% female, 65% male; 84% native AV fistula, 16% PTFE shunt). Results were then correlated with clinical parameters and bioimpedance measurements (BCM, Fresenius).
Findings included the following:
- In 7% of the patients, CI was elevated over 4 L/min/m²; 9% had low CI.
- Elevated AF >1.75 l/min was found in 24 % of the patients ; 10% had low AF.
- CI corrected for AF (= systemic CI) was reduced in 31% of the patients.
- AF and CI show a strong correlation to one another; SCI does not correlate with AF, i.e. the AF increases the CI in the HD patients.
- 17 % of the patients had an increased relative AF exceeding 30%.
- At the end of HD, CI and SCI fell while the AF remained constant.
- Peripheral resistance and heart rate did not change causing systolic blood pressure to fall.
- In 28% of patients, CI fell by more than 20% and was associated with a drop in systolic blood pressure of more than 9 mmHg.
- Still, CI fall had only a weak correlation to the drop in systolic BP.
- Independent predictors were high age and high ultrafiltration. An increased access flow, an increased OH and increased peripheral resistance proved to be protective. The researchers concluded that the proportion of patients with reduced CI, increased relative access flow and drop in CI during HD is high and can be validly recorded using hemodynamic monitoring with the HD03 Monitor.