Part 2. Comparison of emergency washing solutions in 70% hydrofluoric acid-burned human skin in an established ex vivo explants model

Figures & data

Table 1.  Pain and skin lesions: depending on HF concentration.

Pain and Skin lesions	Concentration of HF
Immediate pain and rapid necrosis	50% or greater
Delayed pain and burn 1–8 h	20–50%
Delayed pain and necrosis until 24 h	≤20%

Table 2.  Explants and treatment groups.

Group	Number of Explants	Treatment	Histological sampling Times
T	20	None	T0, 20 s, 5, 10, 15, 30 min, 1, 2, 4 and 24 h
F	18	30 µL (47 µL/cm^2) 70% hydrofluoric acid exposure without washing	20 s, 5, 10, 15, 30 min, 1, 2, 4, and 24 h
FWCaG	16	30 µL (47 µL/cm^2) 70% hydrofluoric acid applied for 20 s, then washing with water + calcium gluconate topically	After the end of washing at: 5, 10, 15, 30 min, 1, 2, 4, and 24 h
FHexa	16	30 µL (47 µL/cm^2) 70% hydrofluoric acid applied for 20 s, then washing with Hexafluorine^® (2 washes with 200 mL each per explant)	After the end of washing at: 5, 10, 15, 30 min, 1, 2, 4, and 24 h

In all treatment groups, 70% HF saturated filter paper disks were left in contact for 20 s and then removed.

Figure 1.  (A) and (B) Exposed 70% HF, nonwashed explants, aspect at 24 h after a 20-sec exposure. Epidermis (A) and dermis (B). At 24 h after a 20-sec exposure, the epidermis presented completely necrotic structures with the appearance of coagulation necrosis. The lesions were less intense in the papillary and reticular dermis

Figure 2.  (A) and (B) HF-exposed explants rinsed with water + CaG, aspect at 24 h after a 20-sec exposure. Epidermis (A) and dermis (B). Edematous changes were visible in the epidermal basal layer at 24 h after a 20-sec exposure. An appearance of coagulation necrosis including pyknotic nuclei and acidophilic cytoplasm was noted in the papillary dermis. These changes were less apparent in the reticular dermis.

Figure 3.  (A) and (B) HF-exposed explants rinsed with Hexafluorine^®; aspect at 24 h after a 20-sec exposure. Epidermis (A) and dermis (B). No deterioration of the structures of either the epidermis or dermis was observed.

Table 3.  Schematic summary of the histological results for all the groups and for each skin layer.

Time of exposure and skin layers		T (Control untreated group) 20 explants	F (HF without washing) 18 explants	FWCaG (HF + water washing + calcium gluconate) 16 explants	FHexa (HF + Hexafluorine^® 400 mL) 16 explants
T0	Epidermis	GM = good morphology	GM	GM	GM
	Papillary dermis
	Reticular dermis
20 s	Epidermis
	Papillary dermis
	Reticular dermis
5 min	Epidermis		PN + AC
	Papillary dermis
	Reticular dermis		PN + CA moderately
10 min	Epidermis		PN= pyknotic nucleiAC = acidophilic cytoplasm
	Papillary dermis
	Reticular dermis
15 min	Epidermis			PN + AC moderately
	Papillary dermis			PN + AC
	Reticular dermis
30 min	Epidermis			Some necrotic cells
	Papillary dermis			GM
	Reticular dermis
1 h	Epidermis
	Papillary dermis
	Reticular dermis
2 h	Epidermis
	Papillary dermis
	Reticular dermis
4 h	Epidermis			Slightly edematous cells with mild acantholysis
	Papillary dermis			GM
	Reticular dermis
24 h	Epidermis		Totally necrotic	Very edematous cells with a very clear cytoplasm
	Papillary dermis		PN + AC	PN + AC
	Reticular dermis			Lesser alterations

GM, good morphology; PN, pyknotic nucleus; AC, acidophilic cytoplasm.

PN and AC are described as part of the appearance of coagulation necrosis.

In all treatment groups, 70% HF saturated filter paper disks were left in contact for 20 s and then removed.