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ENGLISH SPEAKING?: VISIT OUR INTERNATIONAL WEBPAGE ON FLAP MONITORING
XXIV
Congresso della Società Italiana di Microchirurgia – Palermo 20-22 Ottobre 2011
L’USO DEL LASER DOPPLER IN CHIRURGIA
RICOSTRUTTIVA PER IL MONITORAGGIO CONTINUO DEI LEMBI
L’incidenza dell’ischemia dei lembi microchirurgici nei primi giorni post-operatori,in base a quanto riportato sia dalla letteratura che dalle casistiche non pubblicate, varia dallo 0,5 al 10%. Il riconoscimento tardivo dell’evento ischemico, sia esso originato da un problema venoso oppure arterioso, può avere come disastrosa conseguenza la perdita del lembo. Per contro, la rilevazione precoce consente in gran parte dei casi il salvataggio del lembo grazie ad una tempestiva revisione chirurgica. Proprio per le conseguenze drammatiche e gli elevatissimi costi economici della perdita di un lembo, il monitoraggio continuo della loro perfusione è un argomento al quale sono in genere molto sensibili anche i Centri con la più bassa incidenza di “flap failure”. Il sistema laser Doppler Periflux è il più semplice da applicare e da interpretare, e non ha in pratica costi di esercizio.
Al fine del monitoraggio della perfusione dei lembi, sono state adottate e sperimentate diverse tecniche.
· Controlli visivi e funzionali da parte di operatori (spesso studenti, nei centri universitari). Oltre al rischio della soggettività nella diagnosi, questi controlli non possono essere continui ed il riconoscimento dell’ipoperfusione con l’attivazione della procedura di re-intervento esplorativo possono essere tardivi
· la microdialisi: è una tecnica molto costosa (cateteri e reagenti), e complessa, che utilizza un catetere molto delicato, a frequente rischio di rottura. Non è possibile inoltre il monitoraggio continuo. Vengono fatte delle analisi periodiche (tipicamente ogni ora, più il tempo necessario per l’analisi del campione) dei metaboliti raccolti. E’ una interessantissima metodica per la ricerca ma , oltre ad essere molto costosa, non è adatta all’uso clinico. Documentare a posteriori quello che è stato l’andamento metabolico tissutale in un lembo perso è poco utile al paziente
· Il Doppler impiantabile: ha elevati costi di esercizio (parti monouso), rileva la velocità di flusso a livello dell’anastomosi sulla vena o sull’arteria (non su entrambe) ed è solo acustico. Pertanto è un grande fastidio per le persone presenti. Se per eliminare il fastidio si abbassa il volume si rischia di non sentire quando il suono cambia. Se il sensore è posizionato sulla vena, il continuo rumore di fondo non pulsatile porta all’assuefazione e all’indifferenza in caso di riduzione del tono. Se è posizionato sull’arteria pulsante, può rilevare tardivamente un problema venoso. Inoltre non dice nulla sulla perfusione alla periferia del lembo
· La tcpO2 utilizza un elettrodo riscaldato a 44 °C, che deve essere periodicamente spostato e ricalibrato (al massimo ogni 4 ore, e comunque con conseguente eritema cutaneo su un tessuto che si desidera preservare). E’ applicabile solo sulla cute e non su altri tessuti, e richiede una superficie di appoggio del diametro di circa 2,5 cm. Non è dotato di sistemi di allarme
·
La
temperatura tissutale, forse uno dei primi sistemi adottati, in varie
versioni, è comunque un parametro indiretto. Non è però in genere possibile
effettuare un reale monitoraggio con allarmi, e secondo molti autori la
metodica non è sufficientemente accurata.
·
Sistemi ossimetrici ottici tipo NIRS. Elettrodi costosi e difficilmente
riutilizzabili, inoltre poco adatti al monitoraggio in lembi sommersi
· Altri sistemi sperimentali. Con la costante innovazione tecnologica, la possibilità di sperimentare nuove soluzioni è illimitata, purchè si differenzi la sperimentazione dall’utilizzo clinico e agli immediati vantaggi per il paziente.
Spesso nella pratica clinica le aspettative rappresentate da nuove apparecchiature vengono disattese. Per questa ragione proponiamo sempre una prova diretta delle nostre apparecchiature prima dell’acquisto.
Un sistema estremamente semplice, poco costoso, poco invasivo, con elevatissima sensibilità e specificità, idoneo a rilevare problemi sia venosi che arteriosi, che non richiede materiale monouso, è il laser Doppler Periflux System 5000. La sonda risterilizzabile (anche per osso) viene suturata sul tessuto e ne legge in modo continuo la perfusione. In caso di occlusione venosa, l’aumento delle resistenze periferiche provoca una rapidissima riduzione del segnale laser Doppler, anche se l’arteria continua ad essere pervia. Un problema ischemico arterioso viene peraltro rilevato istantaneamente, con una caduta del tracciato proporzionale all’entità dell’ipoafflusso.
Un allarme visivo e acustico allerta gli operatori. Possono essere registrati diversi giorni di monitoraggio, con la possibilità di rivederli per analizzare meglio gli eventi perfusi anche in relazione ad altri atti medici o comportamentali del paziente.
Il costo del PeriFlux per questo tipo di applicazione viene recuperato anche in caso di un solo salvataggio di lembo nel corso di anni.
Sonda
laser Doppler suturata per monitoraggio continuo
Esempio
di ischemia –cliccare sull’immagine per vederla ingrandita
Sonde
con cannula per lettura della perfusione della spongiosa
Sonda
impiantata nell’arco mandibolare
Tracciati su osso sano (sotto: perfusione
più elevata)
e
osso necrotico (sopra: perfusione più scarsa)
Cliccare sull’immagine per ingrandire
Il PeriFlux System 5000 installato su carrello
Richiesta informazioni
Flap Monitoring and
Patient Management
Salgado, Christopher J.
M.D.; Moran, Steven L. M.D.; Mardini, Samir M.D.
Abstract
Summary:
Complications in free-tissue transfer patients cannot be completely prevented;
however, the incidence may be significantly reduced by a thorough preoperative
evaluation and initiation of prophylactic strategies, meticulous surgical
technique, and diligent postoperative monitoring. Emergent exploration must be
performed soon after obstruction occurs if it is to be successful, and early
exploration and repair is likely in compromised flaps if they are monitored
frequently in the initial postoperative period. This article reviews the
importance of clinical management in this patient population, the recommended
frequency of flap monitoring, and the most commonly used methods of monitoring
the transferred tissue whether or not the flap is readily visible. The authors
also review the anticoagulants used and a postoperative flap monitoring
protocol.
Flaps, Free Tissue Transfer
Updated: Jul 7, 2010
Definition
Free tissue transfer is defined as the vascular
detachment of an isolated and specific region of the body (eg,
skin, fat, muscle, bone) followed by transfer of that tissue to another region
of the body with reattachment of the divided artery and vein to separate artery
and vein. This ability to transplant living tissue from one region of the body
to another has greatly facilitated the reconstruction of complex defects.
Free tissue transfer has become commonplace in many centers around the world.
The numerous advantages include stable wound coverage, improved aesthetic and
functional outcomes, and minimal donor site morbidity. Since the introduction
of free tissue transfer in the 1960s, the success rate has improved
substantially and is currently 95-99% among experienced surgeons. This article
provides a framework to facilitate the planning, execution, and monitoring of
free flaps.
For
more information on various flap procedures, see the Flaps section of eMedicine’s Plastic Surgery journal.
Free tissue transfer currently is used for the
reconstruction of complex defects and disorders throughout the body. As with
all techniques in plastic surgery, adherence to the basic principles and
concepts of reconstruction is essential. The "reconstructive ladder"
that all plastic surgeons learn is based on performing the simplest procedure
to correct a particular condition. Although these principles are valuable and
almost always justified, aesthetic and functional considerations occasionally
warrant performing more complicated procedures. These considerations are most
evident following ablative procedures for cancer, for restoration of function,
and for aesthetic appearance.
Numerous
clinical situations exist in which the use of a free flap is justified and
beneficial. Refinements in mandibular reconstructions have led to the use of the free fibular flap, which results in improved
appearance and function of the neomandible. The use
of the muscle-sparing free transverse rectus abdominis myocutaneous (TRAM) and deep inferior epigastric (DIEP)
artery and vein flaps in breast reconstruction allows for excellent shape and
contour of the breast mound while minimizing donor site morbidities related to
abdominal strength and contour.
Innervated free muscle flaps have successfully restored upper extremity and
hand function and the ability to generate facial animation in incidents of
nerve and muscular dysfunction. The use of numerous perforator flaps such as the DIEP flap, superficial inferior epigastric
artery (SIEA) flap, thoracodorsal artery perforator
(TAP) flap, and superior or inferior gluteal (SGAP,
IGAP) flaps have served to further increase the surgeon's options and further
decrease donor site morbidity.1
Preoperative Considerations
Preoperative preparation is an essential component of the successful
free tissue transfer. Preoperative evaluation includes analysis of the
recipient site, consideration of available donor sites, and the clinical status
of the patient. Proper patient selection is of utmost importance when analyzing
outcomes. The specific factors are reviewed below.
Analysis
of recipient and donor sites
Factors
related to the recipient site include the size, depth, and location of the
defect; quality of the surrounding tissue; exposure of vital structures or
hardware; zone of injury; presence of bacterial colonization or infection;
previous irradiation; and functional and aesthetic considerations. Factors
related to the donor site include appropriate tissue match; length of the
vascular pedicle; caliber of recipient vessels; surface area, volume, and
thickness of the flap; and donor site morbidities. Flaps with a short vascular
pedicle requiring a vein graft and flaps with a bone component are associated
with an increased rate of flap loss in some clinical series.2
Some sites, such as the head and neck, have various
recipient vessel options; therefore, a thorough understanding of the anatomy is
essential.3
Clinical
status of the patient
The
clinical status of the patient depends on a variety of factors that also may
impact the free flap. These include advanced age, nutritional status, tobacco
usage, and presence of underlying comorbidities (eg, diabetes mellitus, cardiopulmonary disease, peripheral vascular disease). Although advanced age and tobacco use are not contraindications to
free-flap operations, poor nutritional status can impede wound healing and
recovery. Patients with poorly controlled diabetes mellitus and peripheral
vascular disease require adequate glucose control and may require
revascularization procedures prior to free tissue transfer. Surgical clearance
by a medical physician is recommended for patients with multiple medical
problems.
Donor
tissues
Specific
donor tissues are variable, and donor sites are chosen based on recipient site
requirements. Available tissues include muscle, musculocutaneous,
fasciocutaneous, osteocutaneous,
and bone flaps. In general, free muscle flaps are indicated for soft tissue
coverage of bone and synthetic materials and to obliterate a large dead space.
- Innervated muscle flaps are
useful for facial reanimation operations and for upper extremity
reconstruction.
- Musculocutaneous free flaps are useful for large defects
requiring aesthetic contouring.
- Fasciocutaneous flaps permit tendon gliding in the extremities
and provide excellent contouring of the head and neck.
- Osseous and osteocutaneous free flaps are useful for segmental
bone defects involving the mandible and extremities.
- Adipocutaneous or perforator flaps are especially useful to
minimize donor site morbidity.
- For the irradiated wound,
free tissue transfer is recommended and has been demonstrated to be safe
and well tolerated, with no increased rate of partial or total free flap
loss.
Timing
In
the trauma patient, the timing of free-flap reconstruction is of prime
importance. Free tissue transfer within 3-7 days allows time for adequate
debridement, declaration of the zone of injury, and prevention of chronic
bacterial colonization. Immediate free-flap reconstruction is often preferred
for the acquired operative wound, especially in the presence of vital
structures and hardware and for aesthetic and functional considerations.
Consider delayed free-flap reconstruction when oncologic concerns are present.
Other
considerations
Other
factors that require consideration include choice of anesthesia and patient
position for the operation. Anesthetic options include general, spinal, or
epidural and depend on the nature and location of the reconstruction. General anesthesia is preferred for most patients and can be administered via oral, nasal,
or tracheal routes. Oral intubation is preferred for trunk and extremity
reconstructions; however, nasal and tracheal intubations are preferred for most
reconstructions involving the
head and neck. Spinal anesthesia
occasionally is used for lower extremity free flaps and has the advantage of
providing a transient sympathectomy that promotes
vascular dilation. Epidural anesthesia is primarily used for postoperative pain
management.
Patient
positioning may require an inflatable beanbag, Wilson frame, or Mayfield
headrest. The inflatable beanbag is useful in placing the patient in the
lateral decubitus position (eg,
when harvesting a latissimus dorsi
flap). The Wilson frame or chest rolls benefits patients in the prone position,
allowing chest expansion during general anesthesia.
Intraoperative
Considerations
The operative portion of the free tissue transfer requires absolute attention
to detail. Numerous factors must be considered to predictably obtain a
successful outcome. These include use of appropriate medications and solutions,
properly functioning equipment and instruments, anastomotic
issues, and flap insetting.
Intraoperative medications
Required
medications include intravenous antibiotics, antibiotic solution for wound
irrigation, intravenous heparin administered 5 minutes prior to free flap
harvest, 4% Xylocaine for topical vasodilatation, and
heparin solution (100 U/cm3) for luminal irrigation. Studies evaluating the effects of various intraoperative anticoagulants have demonstrated that the
flap loss rate is lower in patients receiving a heparin bolus of 5000 U only or
a heparin bolus of 2000-3000 U followed by postoperative infusion. Low-dose
heparin does not increase the risk of hematoma or postoperative bleeding. Other
medications that may be used include Decadron 4-8 mg
to reduce edema and swelling (especially for reconstructions of the head), papaverine as an alternate vasodilator, and streptokinase
or urokinase for lysis of intraluminal thrombus.
Anastomoses issues
Various
issues are related to the anastomoses. Factors
contributing to a difficult anastomosis include trauma
to the zone of injury, radiation, scar, and infection. Success can be amplified
by adhering to the some basic principles.
- The nursing staff and
primary surgeon must inspect the micro-instruments and microscope to
ensure proper function.
- The diameter of the artery
and vein, both for the flap and recipient site, should be 1-3 mm to permit
adequate inflow and outflow.
- Blood vessels must be free
of all loose adventitia, and the vascular approximation must be tension
free. Acland clamps should facilitate vascular exposure and manipulation.
- Complete the anastomosis using either a vascular coupler or sew it
by hand. The author prefers to hand sew; however, the coupler has
demonstrated its usefulness, especially for venous anastomoses,
in improving patency and decreasing operative time.
- Complete the hand-sewn anastomosis using 8-0, 9-0, or 10-0 nylon sutures
placed in an interrupted fashion. In general, anastomose
larger caliber vessels (2-3 mm) using 8-0 or 9-0 sutures and smaller
caliber vessels (1-2 mm) using 9-0 or 10-0 sutures.
- Using operative loupes
rather than a microscope has been reported; a minimum of 3.5-power
magnification is recommended.
- The tolerated flap ischemia
times depend upon the composition of the tissues being transferred. In
general, perforator flaps tolerate longer periods of ischemia because no
muscle is involved. Ischemia times of up to 4 hours for a perforator flap
may be well tolerated. Musculocutaneous flaps,
on the other hand, do not tolerate prolonged ischemia times because of the
metabolic requirements of the muscle. In general, 2-3 hours of ischemia is
the maximum time tolerated.4
- Following completion of the anastomoses, the flap must be properly inset. Inspect
the vascular pedicle for kinks, twists, compression, and to ensure that no
tension is present across the anastomosis.
Inspect the distal aspect of the flap for arterial and venous bleeding.
Use a Doppler unit to assess arterial and venous flow through the pedicle
and in the flap. Finally, recheck the vascular pedicle to ensure a gentle,
nontwisting course of the vessels before
completing the final suturing of the flap, especially if the patient's
position has been changed.
- Place a closed suction drain
under the flap away from the anastomoses and
suture the flap in position.
Postoperative
medications
Using
postoperative medications to inhibit clot formation at the anastomosis
is controversial. Studies evaluating the efficacy of heparin, dextran, and aspirin have demonstrated that none is
absolutely necessary for an uncomplicated anastomosis.
However, the author prefers to run intravenous dextran-40 at 30 cm3/h for the first 12-24 hours, followed by oral Ecotrin 325 mg daily for 2-4 weeks.
Postoperative Monitoring
Techniques
to monitor the free flap depend on the tissue composition and location of the
flap. Specific monitoring techniques include evaluation of color, capillary
refill, turgor, surface temperature, presence of
bleeding, skin graft adherence, and auditory assessment of blood flow. Use of
these techniques depends on whether the flap has a fasciocutaneous
component, is covered with a skin graft, or is buried and inaccessible to
visual assessment.
Surface
characteristics
For
the fasciocutaneous, adipocutaneous,
musculocutaneous, and osteocutaneous
flaps, surface characteristics are important. Normal flap color is similar to
that of the recipient site. Normal capillary refill is 1-2 seconds. Surface
temperature of the flap can be monitored using adhesive strips (for an accurate
number) or the back of the hand (to provide a comparative assessment with the
surrounding skin). Problems with arterial inflow are suggested when the flap is
pale relative to the donor site, cool to the touch, and when capillary refill
is slow or absent. Problems with venous outflow are suggested when the flap is
congested, edematous, and when capillary refill is brisk and rapid. Color and
appearance of congested flaps can vary depending on whether the congestion is
mild or severe and ranges from a prominent pinkish hue to a dark bluish purple
color.
Surface
Doppler assessment for flaps with a fasciocutaneous
component may yield a false positive result by picking up signals from
surrounding or deep blood vessels. Characteristics of blood from the flap
following pinprick also can provide clues. Dark venous blood suggests venous
occlusion, and absence of bleeding suggests arterial occlusion.
Muscle
flaps with skin grafts
The
muscle flap covered with a skin graft often is easier to monitor. Surface
temperature and capillary refill generally are not used in these situations;
however, color, turgor, skin graft adherence, and Doppler signals are useful.
Signs of venous outflow obstruction include flap congestion and edema, dark
blood on pinprick, and loss of the venous Doppler signal. Signs of arterial
occlusion include a flat and pale flap, poor skin graft adherence to the flap,
no bleeding on pinprick, and loss of the arterial signal.
Deep
or buried flap
The
most difficult flap to monitor is the deep or buried flap (eg, fibula flap
without a skin paddle). Surface Doppler signals often are unreliable. In these
situations, placing the temporary implantable Doppler probe adjacent to the
artery and vein at the time of operation is useful.
Monitoring the free flap during the postoperative phase is critical to
ensure flap survival. When recognized early and managed promptly (<6 h),
compromised flaps have a 75% salvage rate when taken back to the operating room.
Adipocutaneous flaps can tolerate ischemia better
than musculocutaneous flaps can. Studies have
demonstrated that venous thrombosis alone is more common than either arterial
or combined arterial and venous thrombosis. Thrombosis typically occurs within
the first 2 days in 80% of patients. Thus, all personnel responsible for flap
monitoring must be knowledgeable of the appearance and evaluation of the
healthy and compromised flap.
- Following recognition of
flap compromise, immediately transport the patient to the operating room
for exploration.
- Administer intravenous heparin.
- Inspect the vascular pedicle
for kinks and compression and assess the patency of the anastomosis.
- Identification of thrombus
requires separation of the vessels at the anastomosis.
- Perform embolectomy,
proximally and distally, using a number 2 or 3 Fogarty catheter.
- Administer intraarterial streptokinase or urokinase
at a dose of 50,000-100,000 U as necessary.
- Following restoration of
adequate circulation, inset the flap again and maintain the patient on
intravenous heparin or dextran.
- Failure to restore adequate
circulation requires flap removal.
- The use of medicinal
leeches, Hirudo medicinalis,
has demonstrated value in the treatment of venous congestion.5 This option is indicated
when arterial inflow is adequate but venous outflow is poor. The mechanism
of action depends on the active agent, hirudin, which
is a selective thrombin inhibitor. Apply the leech to the surface of the
flap and surround it with a corral of moistened gauze to prevent leech
migration. Prophylactic antibiotics are recommended to prevent infection
with Aeromonas hydrophila.
Keywords
free
flap, flap, skin flap, transplantation, free flaps, tissue transfer, tissue
transplantation, soft tissue defect, microvascular
free flap, DIEP free flap, free flap surgery, muscle-sparing free transverse
rectus abdominis myocutaneous
flaps, TRAM flaps, deep inferior epigastric artery
flap, DIEP vein flaps, DIEP flaps, breast reconstruction
Monitoring flaps in reconstructive surgery, plasti and maxillo facial, bone perfusion monitorino, monitoraggio dei lembi in chirurgia plastica, determinazione del problema venoso o arterioso, ischemia, cmf these are our keywords, perfusion in bones surgical resection for osteoradionecrosis , radionecrosi