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Ростовский Государственный Медицинский Университет
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Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_3751_Библиотеки_им_академика_М_И_Перельмана

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☆
FIGURE20.1 A,Gasgangrenevisiblewithradiolucencybyfirstmetatarsophalangealjoint.B,Statuspostpartial
firstrayresectionwithexcisionaldebridementofallnonviablesofttissueandbone.C,Postoperativeday2.
Peripheralneuropathyisthemostcommoncauseoffootulcerations,withdiabetesmellitusbeingthemost commoncauseofneuropathy.1Othercausesalso exist,includingmetabolic,toxins,viralandbacterial infections,genetics, ischemia,andinflammatory conditions.Patientswithdiabeteshavea15% lifelong incidenceofdevelopingfootulcers, resultinginover 50%ofnontraumaticlowerlimb amputations.
2-6
Reducedvascularperfusionanddecreasedoxygentothelowerlimbdiminishesthebody’sabilitytoheal suffocatedwoundsites,leadingtoprolongedexposureofopentissuetobacteriaandincreasedlikelihood of bone and soft tissue infection. Additionally, abnormal perfusion of blood to the foot can lead to weakeningof bones.Combiningweakened bones and neuropathycanlead to Charcotneuroarthropathy andmajordeformitiesatriskforwoundsandinfections,increasingthethreatformajorlowerextremity amputation.
7,8
II.InfectionControl
A.RiskFactors
Infection, particularly of an ulcer site, is a significant risk factor for lower extremity amputation.
4,5
Infectionscancauseadelayinwoundhealingwithdeteriorationofthesurroundingtissue.9Causesfor lower extremity infections include vascular impairment, neuropathy, and decreased resistance to infection.
9-12
B.Antibiotics
Control of infection is typically via culture-guided antibiotics. Severe infections require intravenous antibioticswithprophylacticpolymicrobialcoveragepriortocultureresultsincludinggram-positiveand gram-negativeanaerobesandaerobes.13Asdeepwoundculturesbecomeavailable,antibioticcoverage canbenarroweddependingongrowth.Mildsofttissueinfectionsgenerallyrequire2weeksoftherapy.
14
Deepersofttissueinfectionsmayrequireupto2monthsoftreatment.14Osteomyelitisrequires6weeks orlongerofanantibioticregimeninadditiontosurgicalbonedebridement.15Prolongedulcerationsover osseousprominencesshouldbeevaluatedforosteomyelitis.Improperfootwearisthemostcommoncause ofneuropathiculcerations,particularlywhenbonyprominencesorfootdeformitiesexist.
16
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C.Examinations
A biomechanical examination and wound offloading removes abnormally high-pressure areas in a neuropathic patient. Techniques for offloading include accommodative inserts, total contact casting, braces,andtheuseoffelt.Computerizedgaitanalysiseffectivelyassesseshighpedalpressurelocations, leadingtoincreasedorthoticcustomization.Studiesfoundthattotalcontactcastinghealsulcerationsfaster thanhalf shoesandremovablecasts.17Patientsgivenaremovablecastwerefoundtowear itforonly 28% oftheir steps.18Patients undergoing total contactcasting have increased healing asdemonstrated histologicallywithevidenceofangiogenesisandformationofgranulartissueascomparedwithpatients treated with debridement alone.19 Contraindications to nonremovable casts include infection and/or ischemic wounds. Offloading via surgical procedures, such as exostectomies, tendon lengthenings or transfers, fusions,osteotomies,applicationofexternalfixation,and/oramputationsmaybe requiredfor adequate offloading of sites and ultimate wound reduction and prevention. Advanced wound healing productscanalsobeattempted.
D.Osteomyelitis
1.Osteomyelitis,whichonthefoottypicallyoccursatulcerativesiteswithboneprominencesoratdeep
infectionsites,isahighlydestructivecomplicationoftennecessitatinglong-termintravenousantibiotics, surgical debridement, or amputation. The average 5-year patient survival rate after amputation in the diabetic population is 39%.20 Surgically, eliminating thesource of infectionis the primarygoal. The secondary goal involves salvaging the extremity for functional, efficient, and low energy ambulation. During resection, specimens should be obtained of both the infected site and clean margins for pathological and microbiological evaluation. Next, “dead space” must be managed to avoid further complications,includinghematomasandcreationofareasallowingfurtherinfectiousreactions.
2.Sharpdebridementofulcerationsoff-loadssitesbyremovinghyperkeratosis,necrotictissue,foreign
material,andinfectiousorganisms.
15,21
Sharpdebridementshould includethe removal ofallnonviable
softtissueandboneuntilhealthygranularwoundbedsareobtained.Onceinfectionhasbeeneradicated, woundscanbeclosedorcoveredwithprimarywoundclosure,splitthicknessskingrafts,localflaps,or freeflaps.Ifvascularperfusiontotissuesarenotadequate,clostridialcollagenaseisusedforenzymatic debridement of the wound site.22 Hydrocolloid and hydrogel dressings lead to autolysis of necrotic tissues.
3.Avarietyofdressingoptionsforulcerationsareavailableandaredependentuponwoundetiologyand
patientcharacteristics.Treatmentofperipheraledemaisalsobeneficial.
4.Negativepressurewoundtherapy(NPWT)canbeusedtostimulateangiogenesisandtheformationof
granulartissue,decreasingoverallhealingtimeofwounds.
23,24
5. Ifvascular flow is the chiefissue delayingwound healing, revascularization should be attempted.
VascularassessmentincludesDopplerultrasound, duplexultrasound,anklebrachial index, toebrachial index,andangiography.
25,26
Prakashetalfoundthatthepresenceofneuropathyincreasesfootulcerations
and the ischemia worsens the overall presentation.
27,28
Peripheral vascular disease in patients with
diabetes typically involves occlusive arterial lesions involving the femoral-popliteal segment and the tibial arteriesbelowtheknee.28In thediabeticpopulation, chronichyperglycemia leads toendothelial celldysfunction,resultingin anincreaseinthromboxaneA2andadecrease in vasodilators,leadingto hypercoagulationandvasoconstriction.29Inpatientswithperipheralarterialdisease,graftsandbypasses maybeindicated.Ifvascularinterventionsareindicated,theproceduresshouldbeperformedassoonas possible to avoid further tissue degeneration distally. In situations that vascular interventions are not feasible,amputationofthelimbmaybewarranted.
1
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III.AdvancedWoundHealing
A.Phases
Wound healing consists of three phases: acute inflammatory, proliferative, and maturation. The acute inflammatoryphaseconsistsofvasoconstrictionofarteriolesandcapillaries,plateletaggregation,andthe inflammatory cell cascade. The proliferative phase includes fibroblastic activity, extracellular matrix reorganization, and angiogenesis.
30-32
The maturation phase involves the formation of scar tissues in
additiontothesynthesisandbreakdownofcollagen.Numerousadvancedwoundhealingtherapiesexist, ranging from complex biologic dressings, stem cells, laser treatments, hyperbaric oxygen therapies, negativepressurewoundtherapies(NPWT),splintthicknessskingraftsandflaps.
30,31
B.ExtracellularMatrix
Collagen-based modalities provide collagen, themajor protein inthe extracellular matrix. Sustainable extracellularscaffoldsarecompromisedinulcerations,andtreatmentwithcollagenprovidesastructural scaffold matrix to support extracellular components, increase fibroblast proliferation, mediate cell migrationandorganization,andinhibitexcessiveMMPs.
15,33,34
C.NoninvasiveVascularStudies
1.Whenthereisconcernforlimbischemiaorvascularinsufficiencyinthefaceofachronicnonhealing
wound, noninvasive vascular studies can be obtained. Noninvasive vascular studies with preferred parametersincludeanklebrachialindex(ABI)of<0.7,toebrachialindex(TBI)<0.4,ortranscutaneous oxygen tension (TcPO2) levels <30 mm Hg. Abnormal values increase wound complications.
35-37
Arteriographycanbeperformedforevaluationofthearterialtree.Sixangiosomesexistinthefootand ankle38:threefrom the posterior tibialartery,twofromtheperonealartery,andonefromthedorsalis pedisartery.38Arteriographycandetermine ifanangiosomeisnotperfusedatan areaofulceration.It alsoassistswithlocationofflapformationorincisionplacement.Ifrevascularizationcanbeperformed, directrevascularizationofanulceration’sangiosomeyieldsahigherhealingrateofwoundhealing.39If revascularizationcannotbeachieved,hyperbaricoxygentherapycanbeattemptedwithischemicwounds. It exposes patients to 100% oxygen at 2-3 times the normal atmospheric pressure, increasing the saturationofoxygeninthebloodtodecreasehypoxiaandedemaandpromotewoundhealing.
40
2. After revascularization, when a healthy and granular wound bed is achieved, split thickness skin
grafting (STSG) can be performed. The procedure includes harvesting skin from a donor site and transplantingittoarecipientsite.Duringthisprocess,theharvestedskinisseparatedfromitslocalblood supplyandiscompletelydependentontherecipientsite’sbloodsupplyforsurvival(Fig.20.2).41Ifthe typeofwounddoesnotindicateSTSGforclosureanddirectclosurecannotbeattained,flapclosurecan beattempted.
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FIGURE20.2 Dorsalrightfootwoundtreatedwithexcisionaldebridement,STSGapplication,andnegative
pressuretherapy.A,Dorsalfootwound,(B)postsurgicaldebridement,(C)applicationofSTSG,(D)negative
pressuretherapy,(E,F)completionofwoundclosure.
3.Flapsaretissuesutilizedfortransplantationvascularizedbyastemorpedicle.
42
Flaps may include
epidermis,dermis,subcutaneoustissue,underlingfascia,ormuscle.Differentflaptechniquesutilizedin plasticandreconstructiveinterventionsforwoundsincludeadvancement,rotational,andtranspositional flaps(Fig.20.3).Fourmainfeaturesforconsiderationindeterminingincisionsforflapformationinclude adequate exposure, adequate blood supply, sparingof sensory and motor nerves, and attention toskin tensionlines.43Skinincisionsplacedperpendiculartoskintensionlinescanincreasescarcontractures. These types offlaps are perfused by a perforator artery from the dermis tothe subdermal plexus and differ from an axial flap, which has a direct cutaneous vascular supply. Angiosomes evaluation is essentialasrandomflapsrelyonperforatorsforsurvival.
44
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FIGURE20.3 Rhomboidtranspositionalflap.A,Drawingflapoutpriortoincisiontoensureappropriateskintension
forclosureandmeasurementsforcoverage,(B)raisingtheflapfullthicknesstolevelofbone,(C)flapinsetwith
closure,(D)finalclosureappearance.
4.Chokevesselslinkadjacentangiosomesandcanbeusedtoenhanceperfusiontoanangiosome.
44
The
delayphenomenonresultsinthedilationofexistingchokevesselswithintheflapratherthananingrowth ofnewvessels,increasingoverallperfusiontothesite.45Raisingtheflapcausesalocalsympathectomy inthedelayphenomenon,leadingtovasodilation.44Distantaxialflaps,tissueexpansion,andfreeflaps can be performed when split thickness skin grafting and local random flaps are not suitable. These techniquesaremorecomplexwithincreasedriskformorbidity.
IV.Summary
Ischemia,trauma,gasgangrene,septicjoints,necrotizingfasciitis,anddeformitiesandulcerationsleading toinfectionsandosteomyelitiscanhavedetrimental effectsofthelower extremity.Salvagingthelower extremityforfunctional,efficient,andlowenergyambulationistheultimategoalaftertreatingtheprimary source for an at risk foot. When ischemia is leading to the pedal complications, the limb requires evaluation to determine whether efficient blood flow exists for tissue oxygenation. If inefficient flow exists, revascularization should be attempted. If revascularization is unable to be attempted or is ineffective, modalities, including hyperbaric oxygen, can be used. When open wounds exist without infectionandare delayedinclosure,negativepressurewoundtherapy, collagen-basedmodalities, skin
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grafts,andskinflapscanbeutilizedtoattemptclosurepriortonewinfectionagainputtingthefootatrisk foramputation.Limb salvageis nottypicallya one-stagesurgical procedureandmay require multiple interventionsbeforedesiredresultsareattained.Ultimately,inadditiontoaskilledmultispecialtyhealth careteam,extensiveamountsoftimeandcompliantpatientswithpostoperativeprotocolsarenecessaryto achievelimbsalvage.
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C H A P T E R  2 1
PulmonaryVascularDiseasesandInterventions
EileenM.HarderMD
WassimH.FaresMD,MSc
I.PulmonaryVascularDisease
II.AcutePulmonaryEmboli
A.Epidemiology
B.RiskFactors
C.Pathophysiology
D.Classification
E.Presentation
F.Diagnosis
G.Treatment
III.PulmonaryHypertension
A.Definition
B.Epidemiology
C.PulmonaryArterialHypertension(WHOPHGroup1)
D.AtrialSeptalDefects
E.OtherFormsofPAH-CHD
F.PortopulmonaryHypertension
G.ChronicThromboembolicPulmonaryHypertension
IV.Conclusions
KeyPoints
■Depending onpatient comorbidities and theseverity ofthe insult,PEsmaycauseawide
varietyofsymptoms,rangingfromnonetodyspneatosuddendeath.
■PEscanbeclassifiedbymortalityrisk:high(massive),intermediate(submassive),andlow
(nonsubmassive).Thesegroupsaredefinedclinicallybycertainprognosticfactors.
■PEtreatmentdependsontheriskgroup.
■PHhasmanydifferentetiologies,andtheWorldHealthOrganization(WHO)separatesthis
diseaseintofivedifferentclasses.
■ThebestscreeningtestforanysuspectedPHistransthoracicechocardiography(TTE).
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■WHOgroup1PHispulmonaryarterialhypertension(PAH).Itcanbeidiopathic,heritable,
drugortoxinrelated,orassociatedwithcertainconditionsincludingcongenitalheartdisease orportalhypertension.
■IfTTEsuggestsPAH,definitivediagnosisismadebyrightheartcatheterization(RHC).
■PAHtreatmentdependsonthecauseofPHanddiseaseseverity.Itofteninvolvesadvanced
medicaltherapy;certainformsofPAHmayrequiresurgery.
■WHOgroup4PHiscausedbychronicpulmonaryemboli(CTEPH).
ClinicalPearls
■High-riskPEsaredefinedbyhemodynamicinstability(sustainedhypotensionorshock).
■IntermediatePEsarehemodynamicallystablebuthaveevidenceofRVdysfunctionand/or
myocardialinjury.Allofthesefeaturesareabsentinlow-riskPEs.
■Inhemodynamicallyunstablepatients,PEcanbediagnosedbyTTE.Stablepatientsshould
undergoCTpulmonaryangiogram(CTPA).
■Patients with high-risk PEs should receive urgent treatment with systemic thrombolysis,
surgicalembolectomy,orcatheter-basedmethods,asappropriate.
■Intermediateandlow-riskPEsshouldreceiveanticoagulation.
■PAHonRHCisdefinedasameanPAP≥25mmHgwithpulmonaryarterywedgepressure
(PAWP)≤15mmHgandpulmonaryvascularresistance(PVR)>3Woodunits.
■Treatment of PAH may entail calcium channel blockers (for the small number of
vasoreactivepatients)oradvancedtherapy.
■Uncorrected atrial septal defects (ASDs) may also cause PAH. Patients with ASD-PAH
shouldundergoearlyclosure,providedthattheydonothaveEisenmengersyndrome.
■PortopulmonaryhypertensionisaformofPAHassociatedwithportalhypertension.Liver
transplantisindicatedinpatientswithmPAP<35mmHgandPVR<5Woodunits.
■CTEPHshouldbeconsideredinacutePEpatientswhosedyspneaandothersymptomsdo
notresolveafter3-6months.
■In suspected CTEPH, a positive TTE is followed by a ventilation/perfusion scan. RHC
and/orpulmonaryangiographyarerequiredtoconfirmthediagnosis.
■The only definitive treatment for CTEPH is pulmonary endarterectomy (PEA). Balloon
pulmonaryangioplastyoradvancedtherapymaybeconsideredinnon-PEAcandidates.
I.PulmonaryVascularDisease
Pulmonaryvasculardisease(PVD)referstoanydiseasethataffectsthepulmonaryvessels.Thetwomost commonconditions are pulmonaryemboli and pulmonaryhypertension, and this chapter will focus on thesediseasesandtheirmanagement.
II.AcutePulmonaryEmboli
A.Epidemiology
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Anacutepulmonaryembolus(PE)occurswhenapulmonaryartery(PA)oroneofitsbranchesbecomes obstructed,mostcommonlybythrombus.TheincidenceofPEsisunknown,andthismaybeduepartlyto underdiagnosis—silentPEsmayoccurinupto30%-50%ofdeepvenousthrombosis(DVT)cases,and theyareoftenonlynotedincidentallyonautopsy.
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Recentestimatessuggestthatthereareapproximately
600,000 PEs inthe UnitedStates per year, and it may contribute to death in up toone-third of these patients.
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B.RiskFactors
TherearemanyinheritedandacquiredPEriskfactors.Inheritedfactorsincludehypercoagulablestates, such as factor V Leiden or prothrombin mutations, protein C or S deficiencies, and antithrombin deficiency. Important acquired risk factors include older age,major or orthopedic surgery, leg or hip fractures,cancer,immobility,spinalcordinjury,priorPE/DVT,obesity,pregnancy,oralcontraceptiveor hormone replacement therapy, andantiphospholipid antibody syndrome, among others.
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For patients
withDVTs,PEriskisparticularlyhighwithproximalthighclots.
C.Pathophysiology
PEsandDVTsaretypesofvenousthromboembolism,inwhichclotformationisbasedonVirchowtriad ofvenousstasis,hypercoagulability,andendothelialinjury.Innormallungs,perfusionmatchesventilation —hypoxic vasoconstriction occurs in poorly ventilated areas, and well-oxygenated regions remain perfused.PEscreateaventilation-perfusionmismatch.Inthemostseverecases,perfusioniscompletely absentandsystemicshuntingofdeoxygenatedbloodoccurs.
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Thisresultsinhypoxemia,whichisfurther
worsenedbycytokinesthatpromoteinflammationandvasocontriction.9Compensatoryhyperventilation occurs and as a result, respiratory alkalosis with low P
CO2
 is usually present.9 Hypercapnia should increasesuspicionforamassiveembolism.
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PEs also cause circulatory dysfunction. Generally, hemodynamic abnormalities occur only when ≥30%-50% of the pulmonary arterial system is occluded, although even a small clot can cause dysfunction in patients with heart and lung disease.
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Obstructed vessels and the accompanying
vasoconstrictionofnormalvasculaturecauseasuddenriseinpulmonaryvascularresistance(PVR)and acute pulmonary hypertension (PH).The increased afterloaddilatesthe rightventricle (RV), decreases myocardial contractility, and diminishescoronaryvessel perfusion.12 A normal, nonweakened RV can generatea systolicpressureupto 40 mmHg,but abovethisin theacute setting,RV failureoccurs.
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Right-sided strokevolume (SV) and cardiac output(CO) are reduced. Asthe RV furtherstretches,the septummovesintotheleftventricle(LV).Theendresultisdecreasedleft-sidedfilling,preload,andCO.
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ThebodytriggersacomplexcompensatorycascadeincludingsympatheticactivationtoincreasePAflow andpreservesystemiccirculation.8Dependingontheseverityoftheinsult,aPEcanmanifestasawide spectrumoffindingsrangingfromnohemodynamicabnormalitiestoRVfailure,hypotension,andshock. In the most severe cases, compensation is inadequate and sudden death occurs, often by pulseless electricalactivityorasystole.
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D.Classification
AlthoughPEscanbeclassifiedinmultipledifferentways,themostclinically relevantsystem stratifies disease severity based on mortality risk—high, intermediate, or low.
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These terms correspond to
massive,submassive,andnonsubmassivePEs,respectively. High-risk(massive)diseaseisdefinedbythepresenceofsustainedhypotensionorshockinthesettingof
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