Ventilation with high tidal volume induces inflammatory lung injury

Mechanical ventilation with high tidal volumes (V T) has been shown to induce lung injury. We examined the hypothesis that this procedure induces lung injury with inflammatory features. Anesthetized male Wistar rats were randomized into three groups: group 1 (N = 12): V T = 7 ml/kg, respiratory rate (RR) = 50 breaths/min; group 2 (N = 10): V T = 21 ml/kg, RR = 16 breaths/min; group 3 (N = 11): V T = 42 ml/kg, RR = 8 breaths/min. The animals were ventilated with fraction of inspired oxygen of 1 and positive end-expiratory pressure of 2 cmH2O. After 4 h of ventilation, group 3, compared to groups 1 and 2, had lower PaO2 [280 (range 73-458) vs 517 (range 307-596), and 547 mmHg (range 330-662), respectively, P<0.05], higher wet lung weight [3.62 ± 0.91 vs 1.69 ± 0.48 and 1.44 ± 0.20 g, respectively, P<0.05], and higher wet lung weight/dry lung weight ratio [18.14 (range 11.55-26.31) vs 7.80 (range 4.79-12.18), and 6.34 (range 5.92-7.04), respectively, P<0.05]. Total cell and neutrophil counts were higher in group 3 compared to groups 1 and 2 (P<0.05), as were baseline TNF-alpha concentrations [134 (range <10-386) vs 16 (range <10-24), and 17 pg/ml (range <10-23), respectively, P<0.05]. Serum TNF-alpha concentrations reached a higher level in group 3, but without statistical significance. These results suggest that mechanical ventilation with high V T induces lung injury with inflammatory characteristics. This ventilatory strategy can affect the release of TNF-alpha in the lungs and can reach the systemic circulation, a finding that may have relevance for the development of a systemic inflammatory response

Effect of n-acetylcysteine in a random skin flap after administration of nicotine, in the rat

This study analyzed the perfusion of a random skin flap, after nicotine injection and administration of N-acetylcysteine (NAC). A skin flap was elevated after 6 weeks of nicotine administartion and the percentage of necrosis was determined thereafter, as well as malondialdehyde (MDA) in 4 selected skin areas and in serum. Both nicotine and NAC elicited elevation in MDA levels in the skin samples. Nicotine also led to elevation in serum MDA levels and in the percentage of flap necrosis. NAC did not improve the viability of the flap.

Effect of nicotine in randomized skin flaps in rats

This study analyzed the perfusion of randomized skin flaps in rats after nicotine injections, in doses that could be compared with heavy and light smorkers. A skin flap was elevated after 12 weeks of nicotine adminsitration and the percentage of necrotic area was determined thereafter. There was a statistically significant difference between "heavy smokers" in the preoperative (G3) and preoperative and postoperative periods (G5), suggesting a deleterious effect of nicotine in the postoperative period