Ischaemia vs Necrosis: What Every Injector Must Be Able to Spot

An intermediate-to-advanced clinical safety guide for aesthetic injectors

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Introduction

Vascular compromise is the most serious non-ophthalmic complication of dermal filler injection. When filler occludes or compresses a facial artery, whether through direct intravascular injection or external pressure on a vessel, tissue downstream is deprived of oxygen. What follows is a predictable but rapidly evolving sequence: from ischaemia through impending necrosis to established tissue loss and, in cases where intervention is delayed or incomplete, an open wound requiring active management. The difference between a patient who recovers fully and one who sustains permanent scarring lies almost entirely in how quickly the injector recognises what is happening and acts.

Despite this, the early clinical signs of vascular occlusion remain poorly recognised in practice. Beleznay et al. (2019), in an updated global review of filler-related visual and vascular complications, found that delayed recognition and treatment were consistent factors in cases with poor outcomes. Blanching, mottling, and pain are not incidental post-procedure findings — they are emergency signals. DeLorenzi (2014), in the a comprehensive published framework for filler vascular complications, established that the window for effective intervention is measured in hours.

This blog provides a structured clinical framework for recognising ischaemia and necrosis, the stages of vascular occlusion, initiating appropriate emergency management, and — critically — managing the wound when tissue breakdown has occurred. The wound care component of vascular occlusion sequelae is underaddressed in the aesthetic literature; Farmer et al. (2021) provide the most comprehensive published guide to this aspect of management, and their framework underpins the wound care section of this blog. For training in complication recognition, hyaluronidase technique, and emergency protocols, explore Acquisition Aesthetics courses.

The Vascular Occlusion Cascade: Pathophysiology

Two mechanisms underlie filler-related vascular compromise:

1. Intravascular Injection

Direct injection of filler into an artery can cause downstream embolisation, occluding smaller vessels and producing ischaemia in dependent tissue. This is the mechanism responsible for the most catastrophic outcomes, including cutaneous necrosis and vision loss. The volume required to cause clinically significant occlusion is small: published case reports document serious events with fractions of a millilitre.

2. External Vascular Compression

Filler deposited adjacent to a vessel can compress it through a pressure effect, reducing or occluding flow without entering the lumen. This mechanism is more insidious — onset of ischaemia may be delayed by minutes to hours as the filler bolus exerts progressive pressure or the vessel goes into reactive spasm. It is particularly relevant in tightly compartmentalised zones such as the nose and temple.

Reperfusion Injury: An Underappreciated Complication

Tissue damage does not stop at the moment of ischaemic insult. Farmer et al. (2021) highlight a critical but underappreciated phenomenon: when vascular supply is re-established after prolonged ischaemia — whether through hyaluronidase-mediated dissolution, collateral flow, or spontaneous vessel recovery — the return of oxygenated blood triggers enzymatic reactions that produce harmful reactive oxygen species (superoxide, hydrogen peroxide, hydroxyl free radicals). These free radicals damage endothelial cells, impair bacterial killing, reduce nitric oxide levels, and drive a localised pro-inflammatory cascade. In practical terms: if significant ischaemia has persisted for many hours, successful reperfusion may accelerate breakdown of already-compromised tissue. This underscores the urgency of early intervention — the shorter the ischaemic period, the less severe the reperfusion injury.

Stages of Vascular Occlusion

Farmer et al. (2021) published a staging framework as part of a comprehensive guide to ischaemic wound management. It provides injectors with a structured, stage-specific framework for both prognosis and management decisions.

Stage	Pathophysiology	Typical Onset and Clinical Correlate
Stage 1 Pallor	Immediate arterial blockage or spasm causing abrupt interruption of blood flow and tissue perfusion.	Instant; may last seconds or persist. White or pale skin along an anatomical distribution. Reversible if treated promptly — does not necessarily progress to necrosis.
Stage 2 Livedo Reticularis	Build-up of deoxygenated blood within the surrounding venous network; partial perfusion via collateral circulation.	Can occur rapidly; lasts 24–36 hours. Mottled, reticular (net-like) pattern. Still potentially reversible. Narrowing treatment window.
Stage 3 Pustules	Reduction in tissue pH and sweat production; anaerobic conditions allow Staphylococcus aureus overgrowth as a facultative aerobe through pilosebaceous units.	Approximately 72 hours after occlusion. Marks beginning of necrotic change. Supportive wound care will be required.
Stage 4 Coagulation	Tissue blackens due to worsening hypoxia, cell lysis, and haemorrhage into tissues. Tissue is firm with retained architecture (coagulative necrosis).	Occurs over several days. Established tissue death. Wound management essential. Depth varies; may extend to fat and muscle.
Stage 5 Devitalised Tissue (5A: Slough / 5B: Eschar)	Destruction of tissue; build-up of denatured structural proteins (collagen, fibrin, elastin) and haemoglobin. Slough: moist, yellow/green. Eschar: dry, black.	Occurs over several days to weeks. Specialist wound care required; surgical referral may be needed for deep or extensive eschar.

Depending on which artery is affected, its anatomical variations, and the adequacy of collateral formation, injury may be limited to the dermis or may extend to deeper structures including fat and muscle. Deep injuries may require escalation to secondary care for surgical management.

Recognising Ischaemia: The Early Warning Signs

Ischaemia is a reversible state if treated promptly. Its early signs can be subtle, easily attributed to post-procedure changes, or obscured by topical anaesthetic or erythema. Every injector must be able to identify these signs in real time.

Immediate Signs (During or Within Minutes of Injection)

⚠️  Immediate Red Flags — Stop Injecting Now Sudden onset pain disproportionate to the injection — especially sharp, burning, or radiatingBlanching (pallor) along an anatomical distribution beyond the immediate injection site (Stage 1)Mottled, reticular pattern developing over the injection zone (Stage 2)Patient reports visual changes, blurring, or loss of field — ophthalmic emergencyPain that does not resolve within 30–60 seconds of stopping injectionCapillary refill time is >2s

Blanching immediately after injection is the most important early sign. A normal tissue response is transient erythema from mechanical trauma. Blanching — white or pale skin — indicates arterial occlusion or spasm, not normal post-injection change.

Capillary refill assessment is key: press firmly for 3 seconds and release. Normal refill is under 2 seconds; delayed or absent refill confirms impaired perfusion.

Distinguishing Ischaemic from Vasovagal Blanching

Vasovagal blanching involves global pallor, systemic features (faintness, bradycardia, nausea), and rapid resolution on lying the patient flat. Ischaemic blanching is localised — it follows an anatomical vascular distribution, does not resolve with position, and is accompanied by site-specific pain. Treating vasovagal blanching as ischaemia delays the patient’s recovery; treating ischaemic blanching as vasovagal is potentially catastrophic.

When Tissue Is Lost: Wound Management After Vascular Occlusion

When ischaemia progresses to Stage 3 or beyond, tissue breakdown is inevitable and wound management becomes the primary clinical task. This aspect of vascular occlusion sequelae is critically underaddressed in aesthetic practice — despite the fact that wounds not managed correctly can result in permanent scarring and significant patient distress.

Patients who seek aesthetic treatment are particularly vulnerable to poor wound outcomes: they have pursued treatment to improve their appearance, and a wound or scar represents a qualitatively different kind of harm. Drug adjuvants (antibiotics, steroids, nitrate preparations) alone are not sufficient for optimal wound healing. The wound must be actively managed with appropriate topical agents from the outset.

The Four Stages of Wound Healing in Ischaemic Wounds

Facial wounds resulting from a filler vascular event enter the wound healing cycle at the inflammation stage — they are not traumatic wounds from initial injury but present when ischaemic tissue breaks down.

Wound Healing Stage	Clinical Features and Management Priorities
Stage 1: Inflammation	Erythema, oedema, pain, and exudate. Pustules may be present. A wound stuck in this stage will not progress to healing. Initiate moist wound healing immediately. Debride slough. Avoid prophylactic oral antibiotics unless systemic infection is present.
Stage 2: Proliferation	Angiogenesis and granulation tissue formation. Typically lasts 2–4 weeks. Granulation tissue should appear pink; dark red, friable, or bleeding tissue indicates abnormality. High-protein diet and good hydration support this stage. Educate patients on smoking cessation — nicotine is a vasoconstrictor that prolongs ischaemia and impairs granulation.
Stage 3: Epithelialisation	Epidermal resurfacing. A moist wound environment is essential — wounds treated with moist healing principles at all prior stages re-epithelialise more rapidly with better long-term scar outcomes. Winter’s landmark 1963 research established that occluded wounds heal faster than uncovered ones; this principle remains foundational.
Stage 4: Remodelling	Collagen synthesis and extracellular matrix restoration. Can begin as early as 21 days after injury or be delayed for years depending on ischaemia depth and duration. Silicone gel or sheeting should be applied once the wound has closed by primary intention and continued for 2–6 months to reduce disorganised collagen formation and risk of hypertrophic scarring.

The Principle of Moist Wound Healing

The single most important principle in managing ischaemic facial wounds is maintaining a moist wound environment. Wounds that are allowed to dry out are at significantly increased risk of secondary complications, infection, delayed healing, PIH, and scarring. A dry wound is not a healing wound. Moist wound healing — the benefits of which have been documented for over 60 years — increases re-epithelialisation rates, reduces infection risk, and improves long-term scar outcomes. This principle must be applied from the moment skin breakdown is identified, not retrospectively once a wound is established.

Factors That Affect Wound Healing Outcomes

The following patient-related factors may impair wound healing following ischaemic injury and should be assessed during clinical history. Recognising them allows the injector to anticipate delayed healing, explain it to the patient, and adjust the wound management plan accordingly:

• Age: epidermal thinning and reduced inflammatory response with advancing age delay all wound healing phases
• Smoking: nicotine causes vasoconstriction, increases platelet adhesiveness, decreases fibroblast and macrophage activity, and augments tissue hypoxia — significantly impairing every stage of healing
• Diabetes mellitus: impairs leukocyte migration, reduces tissue oxygen concentrations, delays angiogenesis, and disrupts keratinocyte and fibroblast development
• Medications: corticosteroids reduce growth factor release and fibroblast activity; chemotherapeutics impair cellular proliferation; anticoagulants and biologics may also affect wound healing progression
• Malnutrition: adequate vitamins, minerals, protein, and fatty acids are required for wound repair; protein deficiency specifically delays transition from inflammation to remodelling
• Genetic predisposition: keloid scarring has a strong hereditary component with higher incidence in African, Asian, and Hispanic ancestry; Ehlers-Danlos syndrome is associated with impaired wound healing and skin fragility

A thorough patient history before aesthetic procedures — including these wound healing risk factors — is both a safety measure and a medicolegal requirement. If a complication occurs in a high-risk patient, prior documentation of the risk discussion will be important.

Summary for Injectors

• Vascular occlusion follows stages from pallor to devitalised tissue. Stages 1 and 2 are potentially fully reversible; progression to Stage 3 or beyond indicates that wound care will be required (Farmer et al., 2021; DeLorenzi, 2014).
• Blanching (Stage 1) is the critical early sign and demands immediate action. Mottling (Stage 2) indicates narrowing of the reversal window. Pustule formation (Stage 3) marks the onset of necrotic change.
• Reperfusion injury is a real phenomenon: prolonged ischaemia means that restoring blood flow can accelerate tissue breakdown. This is an additional reason to intervene as early as possible, not a reason to avoid treatment (Farmer et al., 2021).
• Administer hyaluronidase immediately on suspicion — high-dose, pulsed, broadly distributed across the ischaemic zone. Repeat every 60 minutes as required. The emergency dose is categorically different from the elective dissolution dose (DeLorenzi, 2017).
• Treating within the first three days produces the best wound outcomes. After Day 3, wounds in the inflammatory stage will not progress without active management (Hong et al., 2017).
• Moist wound healing is the foundational principle of ischaemic wound management. Wounds allowed to dry out will not heal optimally and carry significantly higher risk of PIH and scarring. Initiate topical wound management as soon as skin breakdown is identified (Farmer et al., 2021).
• Oral antibiotics are not first-line treatment for localised wound infection. Use topical antimicrobials for wound bioburden; reserve systemic antibiotics for systemic signs of infection.
• Visual symptoms are a medical emergency. Call 999, administer hyaluronidase, and arrange immediate ophthalmology transfer (Carruthers et al., 2014).
• Patient-level factors — smoking, diabetes, age, medications, genetic predisposition — affect wound healing outcomes and should be documented in the pre-treatment history (Farmer et al., 2021).

Train to Recognise, Manage, and Document Vascular Complications With Confidence Spotting ischaemia before it becomes necrosis — and managing the wound when it does — are clinical skills that must be taught, practised, and embedded in every injector’s practice. At Acquisition Aesthetics, complication recognition, hyaluronidase technique, and emergency management protocols are core components of our training from Foundation to Level 7 Diploma, so you are equipped to protect your patients when it matters most. ➤ Explore Our Courses and Book Your Place

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References

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Farmer A, Murray G, Croasdell B, Davies E, Convery C, Walker L.. Facial vascular events and tissue ischemia: a guide to understanding and optimizing wound care.. J Clin Aesthet Dermatol. 2021;14(12 Suppl 1):S39–S48..

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Hong JY, Seok J, Ahn GR, et al.. Impending skin necrosis after dermal filler injection: a ‘golden time’ for first-aid intervention.. Dermatol Ther. 2017;30(6):e12440..

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Signorini M, Liew S, Sundaram H, et al.. Global aesthetics consensus: avoidance and management of complications from hyaluronic acid fillers — evidence and opinion-based recommendations.. Plast Reconstr Surg. 2016;137(6):961e–971e..