perfusion

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Perfusion

Vascular perfusion field representing dermal microvasculature density and integrity.

Biology

Dermal microvasculature provides oxygen and nutrients to the epidermis. Three vascular sub-layers have distinct perfusion characteristics: papillary dermis has dense capillary loops (highest perfusion), reticular dermis has arterioles and venules (moderate), and hypodermis has sparse large vessels (lowest). Wounding destroys vessels in the wound cylinder. Recovery occurs through angiogenesis (capillary sprouting from intact vessels), which is gated by tissue presence above the wound and modulated by VEGF when the angiogenesis module is enabled. Vascular perfusion directly controls O2 and water supply to the epidermis, making it a critical upstream field.

Model

• Vascular PDE with diffusion (capillary sprouting) and no decay (stable vessels)
• Per-layer initialization profile based on Braverman 2000 (papillary=1.0, reticular=0.7, hypodermis=0.3)
• Wound response: zeros vascular field in wound dermis
• Source term: angiogenesis recovery gated by Stratum field (tissue presence required for growth factor signals)
• Per-layer rate factors for recovery (papillary fastest, hypodermis slowest)
• When angiogenesis module is enabled, recovery rate is modulated by local VEGF concentration
• Runs first in CompositeField so O2 and Water read updated perfusion each step

Parameters

From modules/perfusion/config.toml:

Parameter	Default	Units	Description	Source
diffusion	0.03	-	Capillary sprouting / lateral spread	Calibrated
decay	0.0	-	No decay (stable vessels)	Convention
basal	1.0	normalized	Healthy dermis = fully perfused	Convention
angio_rate	0.005	per step	Angiogenesis recovery speed	Schugart et al. 2008 (DOI)
angio_delay_h	24	hours	Hours before sprouting begins	Singer & Clark 1999 (DOI)
papillary_fraction	1.0	fraction	Dense capillary loops	Braverman 2000 (DOI)
reticular_fraction	0.7	fraction	Arterioles and venules	Braverman 2000
hypodermis_fraction	0.3	fraction	Sparse large vessels	Braverman 2000
angio_papillary_factor	1.5	multiplier	Capillaries regrow fastest	Calibrated
angio_reticular_factor	1.0	multiplier	Baseline rate	Calibrated
angio_hypodermis_factor	0.5	multiplier	Deep vessels recover slowly	Calibrated

Coupling

Reads

Field	Source module	How used
Stratum	tissue	Tissue presence gates angiogenesis recovery
VEGF	angiogenesis	Modulates recovery rate (when angiogenesis enabled)

Writes

Field	Consumer modules	What is written
Vascular	tissue (O2 pinning, Water pinning), fibronectin (serum leakage)	Perfusion density per voxel

Validation

Dataset	Observable	Sources	Notes
perfusion_parameters	Per-layer profiles, recovery kinetics	Braverman 2000, Singer & Clark 1999, Johnson & Wilgus 2014, Flegg et al. 2012	Parameter derivation

Metrics

Column	Units	Description
mean_perfusion_wound	normalized	Mean vascular perfusion in wound dermis

Source files

File	Purpose
vascular.h	Vascular PDE with per-layer profiles and angiogenesis recovery
config.toml	Module configuration