Haematological effect of pulsed ultrasound in acute muscular inflammation in rats.

Objective: To evaluate the effect of low-intensity pulsed ultrasound (LIPUS) on the haematological dynamics of an acute inflammatory process after an iatrogenic muscular lesion.

Design: Controlled laboratory study.

Setting: Research laboratory.

Participants: Eighteen male Wistar rats (weight 350 to 450g) were submitted to surgical incision in the biceps femoris muscle (approximately 50%), and subsequently subdivided into control (n=9) and LIPUS (n=9) groups.

Intervention: Ultrasound (1.0MHz) was applied at the lesion site in the pulsed mode (2ms on, 8ms off) at 0.4W/cm(2) for 3 minutes at 1, 8 and 24 hours post-surgery.

Main Outcome Measures: In these periods, blood was collected through venepuncture of the retro-orbital plexus and evaluated for different types of leukocytes and erythrocytes.

Results: LIPUS reduced the total leukocyte count at 1, 8 and 24 hours post-surgery (1 hour, control 9017.2±481×10(3)/mm(3) vs LIPUS 6189.8±450×10(3)/mm(3); 8 hours, control 8078.2±501×10(3)/mm(3) vs LIPUS 5371.3±378×10(3)/mm(3); 24 hours, control 8192.3±646×10(3)/mm(3) vs LIPUS 6059.1±503×10(3)/mm(3); P<0.001). The monocyte count was reduced at 8 and 24 hours post-surgery (8 hours, control 815.5±126×10(3)/mm(3) vs LIPUS 375.4±70×10(3)/mm(3); 24 hours, control 875.3±124×10(3)/mm(3) vs LIPUS 564.7±56×10(3)/mm(3); P<0.001). The number of segmented neutrophils was only reduced at 1 hour post-surgery (control 5033.1±397×10(3)/mm(3) vs LIPUS 3594.8±191×10(3)/mm(3); P=0.006), and the lymphocyte count was only reduced at 8 hours post-surgery (control 4759.7±459×10(3)/mm(3) vs LIPUS 2584.1±356×10(3)/mm(3); P=0.003). Changes were not observed in the concentrations of young neutrophils, polibocytes and erythrocytes.

Conclusion: LIPUS reduced aspects of the inflammatory process following an acute incisional muscular lesion.