Regional Blood Supply in Gangrene with Vascular Compromise is LOWER Than Normal
In gangrene with vascular compromise, the regional blood supply (RBS) to the affected limb is definitively LOWER than that of a normal limb. This is the fundamental pathophysiology underlying gangrene development.
Pathophysiologic Basis
Gangrene develops specifically because of severe decrease in limb perfusion that is inadequate to sustain tissue viability 1, 2. The defining characteristic of critical limb ischemia (CLI) with gangrene is that resting perfusion falls below the threshold needed to maintain tissue integrity 1.
Specific Hemodynamic Parameters
The affected limb demonstrates markedly reduced blood flow with:
- Ankle pressure <50 mmHg (for ischemic rest pain) or <70 mmHg (for ulcers/gangrene) 3
- Toe pressure <30 mmHg (for ischemic rest pain) or <50 mmHg (for ulcers/gangrene) 3
- Transcutaneous oxygen tension <30 mmHg 3
These values are substantially lower than normal limb perfusion pressures, confirming severely compromised regional blood supply.
Clinical Context
The guidelines consistently define gangrene as tissue necrosis resulting from "severe compromise of blood flow to the affected extremity" 1. This occurs when:
- Arterial occlusive disease creates hemodynamically significant stenoses limiting blood flow 2
- Multisegmental arterial lesions reduce macroscopic blood flow 3
- Microcirculatory dysfunction compounds the perfusion deficit 3
The entire clinical presentation—rest pain, tissue loss, and gangrene—exists precisely because regional blood supply has fallen critically below normal levels 1.
Treatment Rationale
The therapeutic imperative is to restore blood flow through revascularization (endovascular or surgical) to establish "in-line blood flow to the foot" 2. This treatment approach only makes sense because the affected limb has inadequate perfusion compared to normal—if blood supply were normal or elevated, revascularization would be unnecessary and potentially harmful.
Important Caveat
One research study 4 noted that blood flowing FROM gangrenous tissue showed increased RBC aggregability (a rheological abnormality), but this represents a secondary hemorheological disorder, not increased blood flow. The actual volume and pressure of blood supply remains severely reduced in the gangrenous limb.