Haematological effect of pulsed ultrasound in acute muscular inflammation in rats

ObjectiveTo evaluate the effect of low-intensity pulsed ultrasound (LIPUS) on the haematological dynamics of an acute inflammatory process after an iatrogenic muscular lesion.DesignControlled laboratory study.SettingResearch laboratory.ParticipantsEighteen male Wistar rats (weight 350 to 450 g) were submitted to surgical incision in the biceps femoris muscle (approximately 50%), and subsequently subdivided into control (n = 9) and LIPUS (n = 9) groups.InterventionUltrasound (1.0 MHz) was applied at the lesion site in the pulsed mode (2 ms on, 8 ms off) at 0.4 W/cm2 for 3 minutes at 1, 8 and 24 hours post-surgery.Main outcome measuresIn these periods, blood was collected through venepuncture of the retro-orbital plexus and evaluated for different types of leukocytes and erythrocytes.ResultsLIPUS reduced the total leukocyte count at 1, 8 and 24 hours post-surgery (1 hour, control 9017.2 ± 481 × 103/mm3 vs LIPUS 6189.8 ± 450 × 103/mm3; 8 hours, control 8078.2 ± 501 × 103/mm3 vs LIPUS 5371.3 ± 378 × 103/mm3; 24 hours, control 8192.3 ± 646 × 103/mm3 vs LIPUS 6059.1 ± 503 × 103/mm3; P < 0.001). The monocyte count was reduced at 8 and 24 hours post-surgery (8 hours, control 815.5 ± 126 × 103/mm3 vs LIPUS 375.4 ± 70 × 103/mm3; 24 hours, control 875.3 ± 124 × 103/mm3 vs LIPUS 564.7 ± 56 × 103/mm3; P < 0.001). The number of segmented neutrophils was only reduced at 1 hour post-surgery (control 5033.1 ± 397 × 103/mm3 vs LIPUS 3594.8 ± 191 × 103/mm3; P = 0.006), and the lymphocyte count was only reduced at 8 hours post-surgery (control 4759.7 ± 459 × 103/mm3 vs LIPUS 2584.1 ± 356 × 103/mm3; P = 0.003). Changes were not observed in the concentrations of young neutrophils, polibocytes and erythrocytes.ConclusionLIPUS reduced aspects of the inflammatory process following an acute incisional muscular lesion.