Relationship of burn-induced lung lipid peroxidation on the degree of injury after smoke inhalation and a body burn

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Abstract

Design:

Prospective animal study with concurrent controls.

Setting:

An animal laboratory.

Subjects:

Forty-four adult yearling female sheep (weight range 45 to 50 kg).

Interventions:

Forty-four sheep were prepared with lung and prefemoral (soft tissue) lymph fistulas. Twelve breaths of cooled smoke with tidal volume of 10 mL/kg body weight were given to 24 sheep, producing a peak blood carboxyhe-moglobin of 25% to 30%. Twelve sheep also received a 15% total body surface third-degree burn. Sheep were killed at 4 or 24 hrs.

Measurements and Main Results:

Circulating lipid peroxidation was monitored as conjugated dienes and tracheobronchial mucosal and lung parenchyma as malondialdehyde. Antioxidant defenses were monitored by catalase activity. Lung physiologic and histologic changes were compared.

Measurements and Main Results:

We noted intense airways inflammation in both smoke inhalation groups and lung parenchymal inflammation in all groups. Lung lymph flow was modestly increased (two-fold) in the smoke inhalation groups. Alveolar water content was not significantly increased after any injury. Pao2 was decreased at 24 hrs after the smoke insult alone. Parenchymal malondialdehyde content did not increase with the smoke insult alone, but did increase from a control value of 110 ± 20 to 270 ± 24 nmol/g tissue by 4 hrs in the combined burn and smoke injury group, while catalase activity decreased. Airway mucosal malondialdehyde did not increase in any group.

Conclusions:

We conclude that alveolar capillary permeability is not increased early after a moderate smoke injury or smoke injury with burn. Lipid peroxidation is not increased in large airway or lung parenchyma with early after-smoke exposure. The addition of a burn significantly increases lung parenchymal lipid peroxidation, but the oxddant changes do not correspond with the degree of early lung dysfunction. (Crit Care Med 1993; 21:1935–1943)

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