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more resistance (blood flow coming towards the probe) will be louder than the sound intensity from the low resistance (blood flow away from the probe). Increase in the frequency of the probe decreases the distance of detection. For a probe with 8MHz, the distance is 20mm; whereas, with a 10MHz probe, the distance is 12mm 10 . The thickness of skin and subcutaneous tissue also affects the vessel detection. The comparison of 8MHz and 10MHz probes showed the positive prediction value for 8MHz was 89% 11 . There are three patterns of blood flow producing audio outputs 12 . Triphasic occurs in arteries and is due to the combination of ventricular systole, the elasticity of blood vessels and backflow caused by the closure of semilunar valves. Biphasic occurs in distal blood vessels due to ventricular systole and elasticity of the blood vessels. Monophasic occurs when the blood flow is not pulsatile 12 . The use of handheld Doppler in the identification of the vessels is an important adjunct. Due to the wide variations in the distribution of blood vessels and their branching patterns, the extra care has to be undertaken while injecting the filler in the face, especially in the ‘danger zones,’ and specifically the area around the orbit. Use of a superficial veins visualiser (AccuVein®, AccuVein Inc. Huntington, NY, USA) can also help to mark out superficial veins. Conclusion The current technique gives an opportunity to mark the vessels to avoid serious complications of intravascular injections. Declaration of interest None Figure 1–2 © Ahmed, Javaid, andMohmand and there are a range of probes that can be used. The commonly used frequencies are 8MHz and 10MHz. The use of gel improves the ultrasound conduction, while pressure applied by the probe on the vessel to be identified can also help. The direction of blood flow (toward the probe and away from the probe affects the loudness of the pulsating sound). The probe facing against the blood flowwill detect the vessel with relative ease 9 . The sound intensity (loudness) returning from References 1. AmericanSocietyforAestheticPlasticSurgery. AestheticSurgerynationaldatabankstatistics2014. http// :www.surgery.org/sites/default/files/2014-stats. pdfaccessedon01-01-2017 2. BeleznayK,CarruthersJDA,HumphreyS,JonesD. Avoidingandtreatingblindnessfrom filler:areviewof theworld literature.DermatolSurg2015;41:1097-1117 3. ColemanSP.Avoidanceofarterialocclusionfrom injectionofsofttissue fillers.AestheticSurgJ 2002;22:555-57 4. ScheuerJF,SieberDA,PezeshkRA,CampbellCF, GassmanAA,RohrichRJ.Anatomyof thefacial dangerzones:maximizingsafetyduringsoft-tissue filler injection.PlastRecosntrSurg2017;139:50e 5. CarruthersJD,FagienS,RohrichRJ,WeinkleS, CarruthersA.Blindnesscausedbycosmetic filler injection:areviewofcauseandtherapy.Plast ReconstrSurg2014;134:1197-1201 6. NahabedianMY,PatelKM.Maximizingtheuseof thehandheldDoppler inautologousbreasts reconstruction.ClinPlastSurg2011;38:213-18 7. TaylorGI,DoyleM,McCartenG.TheDoppler probeforplanning flaps:anatomicalstudyandclinical applications.BrJPlastSurg1990;43(1):1-16 8. SolomonGA,YaremchukMJ,MansonPN.Doppler ultrasoundsurfacemonitoringofbotharterialand venous flow inclinesfreetissuetransfers.JReconstr Microsurg1986;3(1):39-41 9. MunGH,JeonBJ,Anefficientmethodto increase specificityofacousticDopplersonographyfor planningaperforator flap:perforatorcompression test.PlastReconstrSurg.2006;118(1):296-7 10. SmitJM,KleinS,WerkerPMN.Anoverviewof methodsforvascularmapping intheplanningoffree flaps.JPlastReconstrAesthetSurg2010;63(9):674-82. 11. YuP,YoussefA.EfficacyofthehandheldDoppler inpreoperative identificationofthecutaneous perforators intheanterolateralthigh flap.Plast ReconstrSurg.2006;118(4):928-33;discussion934-5. 12. YoungM,Birch I,PotterAC,SaundersR,HussainS, PellettJ,ReynoldsN,JenkinS,WrightW.A comparisonoftheDopplerultrasound interpretation bystudentandregisteredpodiatrists.JFootAnkle Research2013;6:25 Figure 1 Markings indicating the danger zone areas Knowledge of anatomical locations and danger zones is very important when administering injections Use of handheld Doppler device allows for the vessels to be tracked and marked The depth and anatomical course is provided by the knowledge of facial anatomy Key points The use of gel improves the ultrasound conduction, while pressure applied by the probe on the vessel to be identified can also help. FACIAL DANGER ZONES GLABELLA TEMPLE NOSE PERIORAL AREA (LIPS) INFRAORBITAL REGION NASOLABIAL FOLD CASE STUDY | DOPPLER & INTRAVASCULAR FILLER INJECTION | 32 November/December 2017 | prime-journal.com

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