Microvascular Surgery

Don’t You Want To Know theFlow in Your Micro-vessels?
• Quantify restored flow in the smallest vessels• Improve reattachment and flap flow rates• Measure flow quickly and easily

Microvascular Lit Pack (CV-100-Lit) Rev D 2023

C2797

Microvascular Surgery

Microsurgical Flowprobes take the guessworkout of knowing volume flow.
Transonic® Microsurgical Flowprobes
work with Transonic® Flowmeters
to measure volume flow in 0.5 - 3.8mm blood vessels and grafts. The
non-constrictive Flowprobes use gold
standard transit time ultrasoundtechnology to measure volume bloodflow directly within these small bloodvessels.
The new line of microvascular
Flowprobes now offer the surgeon
a quantitative tool with which they
can objectively assess the quality of
the reconstruction or replantation.
Unseen blood flow obstructions canbe detected intraoperatively andrepaired before leaving the operating
room.

“…TTFV (Transit-time Flow Volume) provides novel physiologic
flap data and identifies flow anastomoses and higher-flow venae
comitantes. These data have clinical value in microsurgery and holdthe potential to reduce microvascular complications and improveoutcomes.“JC Selber, MD, MPH et al“The TTUT measurements consistently correlated with the surgeon’sobservations in all 28 lymphatic vessels — healthy-appearing lymphatic
vessels demonstrated flow values higher than those from unhealthyappearing lymphatic vessels. ...Based on the above findings, weconcluded that TTUT holds promise in 1) guiding the lymphatic vesselselection, 2) confirming anastomotic patency, and that 3) the absence of“wash out” may not unequivocally indicate anastomotic occlusion.”
WF Chen, MD et al“Accurate flow measurements can be of great assistance during vascular
reconstructive surgery. The primary aim with these intraoperative
measurements is to obtain information on the immediate result of thereconstruction, where a technical failure may jeopardize an otherwise
successful operation.”
A Lundell, MD, FACS

No longer will a micro-vascularsurgeon have to rely solely on clinicalimpressions to assess the quality ofthe surgery during the procedure. This
on-the-spot volume flow technology
produces flow information quickly,
accurately, and non-intrusively.
The ability to immediately correctotherwise undetectable flow
restrictions provides the surgeon witha unique opportunity to improve theirpatients’ outcomes.

TRANSIT-TIME ULTRASOUND TECHNOLOGYMEASURES VOLUME FLOW, NOT VELOCITY

Two transducers pass ultrasonic signals, alternately intersecting
the vessel in upstream and downstream directions. The difference
between the two transit times yields a measure of volume flow.

Transonic Systems Inc. is a global manufacturer of innovative biomedical flow
measurement equipment. Founded in 1983, Transonic sells state-of-the-art, transit-time
ultrasound devices for surgical, hemodialysis, perfusion, ECMO, and medical device
testing applications, and for incorporation into leading edge medical devices.

USA/CanadaEurope

Asia/Pacific

Transonic Systems Inc.
Tel: +1 607-257-5300
Fax: +1 607-257-7256
support@transonic.com

Transonic Europe B.V.
Tel: +31 43-407-7200
Fax: +31 43-407-7201
europe@transonic.com

Transonic Asia Inc.
Tel: +886 3399-5806
Fax: +886 3399-5805
support@transonicasia.com

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Japan

Nipro-Transonic Japan Inc.
Tel: +81 04-2946-8541
Fax: +81 04-2946-8542
japan@transonic.com

Microsurgery

Flow-assisted Surgical Techniques & Notes*
Reconstructive Microsurgery Protocol*Flow-Assisted Surgical Techniques (“F•A•S•T”) and Protocols are drawn from surgical experiences by transit-time flow measurement
users and passed along by Transonic for educational purposes. They are not intended to be used as sole basis for diagnosis. Clinicalinterpretation of each patient’s individual case is required.

Introduction

During reconstruction or replantation microsurgery, a surgeon may electto use a Microsurgical Flowprobe as a quantitative intraoperative toolto detect unseen blood flow obstructions which could thus be repaired
before leaving the operating room.3

Measuring Blood Flow1,2

1. Identify Vessels to be measured
Expose and identify arterial inflow and venous outflow vessels to be
used in the reconstruction.
2. Select Flowprobe Size
Measure the vessel diameter of the vessels to be measured with agauge before opening the Flowprobe package. Select a Flowprobe
size so that the vessel will fill between 75% - 100% of the Probe’s
ultrasonic sensing window.
3. Prepare Vessel for Flowprobe
Select a site wide enough to accommodate the Flowprobe’s acoustic
reflector. Clear approximately 1 cm of the vessel of fascia or fat for an
accurate measurement. Fat could interfere with acoustic transmission.
4. Add Couplant to Flowprobe
Fill the window of the Flowprobe with ultrasonic gel or submerge theFlowprobe’s head in saline in the surgical field.
5. Apply Flowprobe
Apply the Flowprobe at right angles to the vessel (Fig. 1)
taking care not to “twist” or “lift” the vessel with theFlowprobe. Apply the Flowprobe so that the entire vessel lies
within the ultrasonic sensing window of the Probe.
6. Check Signal Strength
Check the Flowprobe’s ultrasonic signal strength on the Monitor
display or Flowmeter front panel.
7. Measure Multi-stage Flow(s) as needed4
8. Document Flows for Case Record1,2
When the waveform appears stable (10-15 seconds) record flow, takea snapshot of the measurement or print the waveform to document
flow values. If the Flowmeter displays a negative flow, press the INVERT
button to change the polarity before printing the waveform. Leave theprobe on the vessel until the printing stops or a snapshot or recording
has been captured (8 – 10 seconds).
References:
1 Measuring PeriFlowprobe(CV-180-mn)RevA2018USltr
2 AU-QRG-Optima-EN Rev E
3 Selber JC et al,“A Prospective Study of Transit Time Flow Volume (TTFV) Measurement for Intraoperative Evaluation and Optimization of Free Flaps,” Plast Reconstr Surg. 2013; 131(2): 270-81.
4 Della Puppa A et al, “Intraoperative Flow Measurement by Microflow Probe During Surgery for
Brain Arteriovenous Malformations,” Neurosurg 2015; Jun;11 Suppl 2:268-73.
Microsurgery (CV-120-mn) Rev C 2019 USltr

Flow Measurement1,2,4Select Correct Flowprobe Size
Measure Baseline Flowson arterial inflow and venous outflow vessels

Determine surgical strategy
for flap reconstruction
Measure flows immediately afteranastomosis and reperfusion
Record flow values of arterial
inflows and venous outflows
Flow equal or morethan baseline

Evaluate surgical strategy
vis á vis flow values4
Measure flows 30 minutes
after anastomosis and reperfusion
Compare to other flows anddetermine surgical strategy

Microvascular Surgery

Publication Brief
A Prospective Study of Transit Time Flow Volume(TTFV) Measurement for Intraoperative Evaluation andOptimization of Free Flaps.
Selber JC et al, University of Texas MD Anderson Cancer Center — 2013

OBJECTIVE
To determine if transit-time volume flow measurements would improve decision-making in microvascular freetissue transfer procedures.

STUDY
Transit-time volume flow was measured in 52 consecutive free flaps (five types) by five surgeons. Thirty-eight(73.1%) of the flaps were harvested to reconstruct head and neck defects, while the remaining 14 (26.9%) (allTRAMs) were harvested for breast reconstruction. Flow measurements were performed:• In Situ, after flap elevation and isolation on its pedicle;• Immediately following anastomosis and reperfusion;• Thirty minutes following anastomosis and reperfusion.
Intraoperative decisions based on transit-time volume flow measurements were documented.

RESULTS••••

Arterial inflow was, on average, 1.5 times greater than venous outflow, and arterial resistance was 3.59
times greater than venous resistance (arterial: 9.04 mL/min; venous: 7.24 mL/min)
Free transverse rectus abdominis musculocutaneous (TRAM) flaps had the highest arterial and venous flows(14.2 mL/min; venous: 11.3 mL/min), and free radial forearm flaps (RFF) had the lowest (arterial: 6.33 mL/min; venus 5.29 mL/min).
Compared to the baseline (In Situ) measurement, all flaps had higher flows immediately after transfer(Time 1) (p<0.0001), but no significant differences were seen 30 minutes later (Time 2) (p=0.68). Arterial
resistance, however, increased during that interval (p=0.006).
In more than a third of the cases (19 out of 52), operative decisions on when to revise an anastomosis, weremodified on the basis of transit-time volume flow findings.

CONCLUSION“Transit-time volume flow measurements provide novel physiologic flap data and identify flawed anastomoses
and higher-flow venae comitantes. These data have clinical value in microsurgery and hold the potential toreduce microvascular complications and improve outcomes.“TAKE HOME POINTS••This publication from a microvascular surgeon key opinion leader provides evidence that volume flow
measurements can provide quantifiable measurements of one of the most critical pieces of microvascular
reconstruction: inflow and outflow.
The author notes that perhaps the most compelling finding of the study is that flow measurements could
alter or augment surgical decision making as it had in 36% of the cases in the study. These quantitative
measurements “fill a knowledge gap” in microsurgery.

REFERENCE:
Selber JC, Garvey PB, Clemens MW, Chang EI, Zhang H, Hanasono MM,“A Prospective Study of Transit Time
Flow Volume (TTFV) Measurement for Intraoperative Evaluation and Optimization of Free Flaps,”
Plast Reconstr Surg. 2013; 131(2): 270-81. (Transonic Reference # 9762AHM)
Selber(CV-9762AHM-pb)Rev B2023USltr

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Microvascular Surgery

Publication Brief

Refining Perforator Selection for DIEP
Breast Reconstruction Using Transit-time
Flow Volume Measurements
ObjectiveTo examine the usefulness of transit-time ultrasound volume flow measurements in assessing perforator vessels
in deep inferior epigastric artery perforator (DIEP) flap harvesting and to evaluate their correlation withcomputed tomographic angiography (CTA) and hand-held Doppler signals in identifying perforators.

study••••••

CTA was used to identify abdominal wall perforators for ten consecutive free DIEP breast reconstructions ineight women (two with bilateral mastectomies, six with unilateral).
Abdominal wall perforating vessels >1 mm in diameter were evaluated intraoperatively with a conventional
hand-held 8-MHz Doppler and a transit-time ultrasound flowmeter.
The location of the vessels was correlated with preoperative CTA.
Information about arterial versus venous flow patterns and mean flow values were recorded for each
vessel typically, with a 2 mm Flowprobe, but occasionally, with a 3 mm Flowprobe. Flow values werecorrelated with both CTA and hand-held Doppler signals.
Information about arterial versus venous flow patterns and mean flow values were recorded for eachperforator.
Perforators with high volume flows and an arterial waveform were selected to supply the flap.

results••••

Of the 54 eligible perforators identified, transit-time flow measurements showed arterial flow waveforms
in 15 of 16 perforators identified by CTA and in 2 of the remaining 38 vessels.
Mean flow for the 16 arterial vessels was 5.3 mL/min. Mean flows for the remaining 38 dissected vessels was2.1 mL/min.
Transit-time flow measurement sensitivity in identifying arterial perforators was 94%; specificity was 95%.
Hand-held Doppler was misleading in 70% of vessels.

conclusion•••

Transit-time flow measurements distinguished arterial from venous waveforms in vessels that appear
arterial by hand-held Doppler signals.
CTA and transit-time flow measurements had high correlation.
The use of transit-time flow measurements may prevent poor perfusion seen in some DIEP flaps.

discussion

This group from the University of Toronto tested the use of transit-time ultrasound flowmetry to identify
optimal deep inferior epigastric arterial perforators to harvest for breast reconstruction. Moreover, theysuggest that transit-time flowmetry may be able to predict early patency in completed microvascularanastomoses, as is the case in CABG surgery.

Reference:
Visscher K, Boyd K, Ross DC, Amann J, Temple C, “Refining perforator selection for DIEP breastreconstruction using transit time flow volume measurements,” J Reconstr Microsurg. 2010; 26(5):285-90. (Transonic Reference # 10717AHM)
Visscher(CV-10717AHM-pb)RevA2015USltr		

Microvascular Surgery

Signature Annotated Microvascular References
1 Smith RM, Kang V, Al-Khudari S, “Vessel selection and free flap
monitoring in head and neck microvascular reconstruction,”
World Journal of Otorhinolaryngology 2015 Feb; 5(1): 5-13.
(Transonic Reference # 10250AHR) “Surgical complications are
not uncommon during microvascular free flap reconstructions.
They prolong the procedure and can lead to the need for timeconsuming surgical re-explorations.”
2 Chen WF, Zhao H, ”Transit-time ultrasound technology-assisted
lymphatic super-microsurgery,” J Plast Reconstr Aesthet
Surg. 2015 Nov; 68(11): 1627-8. “The TTUT measurements
consistently correlated with the surgeon’s observations in all
28 lymphatic vessels — healthy-appearing lymphatic vessels
demonstrated flow values higher than those from unhealthyappearing lymphatic vessels. ...Based on the above findings,
we concluded that TTUT holds promise in 1) guiding thelymphatic vessel selection, 2) confirming anastomotic patency,
and that 3) the absence of “wash out” may not unequivocallyindicate anastomotic occlusion.”
3 Selber JC, Garvey PB, Clemens MW, Chang EI, Zhang H,
Hanasono MM, “A Prospective Study of Transit Time Flow
Volume (TTFV) Measurement for Intraoperative Evaluation andOptimization of Free Flaps,” Plast Reconstr Surg. 2013; 131(2):270-81. (Transonic Reference # 9762AHM) “…TTFV (Transittime Flow Volume) provides novel physiologic flap data andidentifies flow anastomoses and higher-flow venae comitantes.
These data have clinical value in microsurgery and hold thepotential to reduce microvascular complications and improveoutcomes.“4 Visscher K, Boyd K, Ross DC, Amann J, Temple C, “Refining perforator selection for DIEP breast reconstruction using transit timeflow volume measurements,” J Reconstr Microsurg. 2010; 26(5):285-90. (Transonic Reference # CV-9953AHM) This study evaluated the correlation among computed tomographic angiography (CTA), intraoperative TTFV measurements, and hand-heldDoppler signals in identifying perforators in ten consecutive free
DIEP breast reconstructions. ”Of the 54 perforators identified,
TTFV showed arterial flow waveforms in 15 of 16 perforators
identified by CTA and in 2 of the remaining 38 vessels. The sensitivity and specificity of TTFV in identifying arterial perforators
were 94 and 95%, respectively. In contradistinction, hand-heldDoppler was misleading in 70% of vessels. TTFV distinguishes
arterial from venous waveforms in vessels that appear arterial byhand-held Doppler signals. CTA and TTFV are highly correlated,
and the use of TTFV may prevent poor perfusion seen in some
DIEP flaps.”

Measurement,” Laryngorhinootologie 2015 Dec 15. (TransonicReference # 10035AHM) This prospective study combined
ultrasound imaging and transit-time flow measurements toassess anastomotic quality of 15 radial forearm flaps. ...“Results:
Mean blood flow immediately after opening the anastomosisand 15 min later were 3.9 and 3.4 ml/min respectively showingno statistically significant difference (p=0.96). ...Conclusion:
Transit time flow measurement contributes to the improvementof anastomotic quality and therefore to the overall outcomeof radial forearm flaps. The examined measurement method
provides objective results and is useful for documentation
purposes.”
6 Takanari K, Kamei Y, Toriyama K, Yagi S, Torii S, “Differences inblood flow volume and vascular resistance between free flaps:
assessment in 58 cases,” J Reconstr Microsurg. 2009 Jan; 25(1):39-45. (Transonic Reference # 10313AH) ”We investigatedblood flow in the flap by transit-time ultrasound flowmeter in
58 free-flap transfers. Flow volume was compared between
flap tissues as vascular resistance in the flap was calculated.
Fasciocutaneous and osteocutaneous flaps had relatively
low blood flow volume, myocutaneous flaps had more, andintraperitoneal flaps had still higher blood flow volume. These
differences were statistically significant. Vascular resistancesignificantly decreased in the same order of comparison.
Our findings will help in selecting the most suitable flaps forreconstructive surgery.”
7 Lorenzetti F, Giordano S, Tukiainen E, “Intraoperativehemodynamic evaluation of the latissimus dorsi muscle flap: aprospective study,” J Reconstr Microsurg. 2012; 28(4): 273-8.
(Transonic Reference # 10035AHM) Measurements of bloodflow were performed intraoperatively in 27 patients using a
2- to 5-mm probe ultrasonic transit-time flowmeter around thedissected vessels. “Registrations were made in the thoracodorsal
artery before and after harvesting the flap, after compressing
and cutting the motor nerve, and after anastomosis. Mean
blood flow of in situ harvested thoracodorsal artery as measuredintraoperatively by transit-time flowmeter was 16.6 ± 11 mL/
min and was significantly increased after raising the flap to
24.0 ± 22 mL/min (p <0.05); it was 25.6 ± 23 mL/min after
compressing the motor nerve and was significantly increased
after cutting the motor nerve to 32.5 ± 26 mL/min (p <0.05). A
significant increase of blood flow to 28.1 ± 19 mL/min was also
detected in the thoracodorsal artery after flap transplantation
with end-to-side anastomosis (p <0.05).”

5 Herberhold S, Röttker J, Bartmann D, Solbach A, Keiner S,Welz A, Bootz F, Laffers W, “Evaluation and Optimizationof Microvascular Arterial Anastomoses by Transit-Time Flow
SignatureMicrovascularReferencesRev B 8-18 USltr

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