Analysis of differential gene expressions of inflammatory and repair-related factors in chronic refractory wounds in clinic / 中华烧伤杂志

Objective@#To compare the tissue morphology and gene expressions of inflammatory and repair-related factors in chronic refractory wound tissue including pressure ulcers and diabetic feet.@*Methods@#During August 2016 to September 2017, 10 samples of prepuce were collected after circumcision of 10 urological patients [all male, aged (38±4) years old] admitted in the First Affiliated Hospital of Nanchang University and included in normal skin group, samples of tissue around the edge of wounds with blood supply were collected from 9 heat or electric burn patients [6 male patients, 3 female patients, aged (51±8) years old], 13 pressure ulcer patients [9 male patients, 4 female patients, aged (51±14) years old] and 10 diabetic foot patients [8 male patients, 2 female patients, aged (61±10) years old] during the operations. The samples were divided into burn wound group (9 samples), pressure ulcer group (13 samples), and diabetic foot group (10 samples). Ten slices were taken from pressure ulcer group and diabetic foot group respectively, and 5 slices in each group were used to observe the tissue morphology and expressions of Ki67 and CD31 of wounds respectively with immunofluorescence method. Ten samples from normal skin group, 9 samples from burn wound group, 13 samples from pressure ulcer group, and 10 samples from diabetic foot group were collected for analysis of mRNA expressions of vascular endothelial growth factor 192 (VEGF192), transforming growth factor β (TGF-β), vascular cell adhesion molecule-1 (VCAM-1), intercellular adhesion molecule-1 (ICAM-1) , interleukin-1β (IL-1β), IL-6, and tumor necrosis factor α (TNF-α) by real time fluorescent quantitative reverse transcription polymerase chain reaction. Data were processed with Mann-Whitney U test and Kruskal-Wallis rank-sum test.@*Results@#(1) The expression level of Ki67 in diabetic foot group (390±100) was higher than that of pressure ulcer group (182±14, Z=-2.611, P<0.01). (2) Although there were a large number of vascular endothelial cells (CD31 positive cells) in wounds of diabetic foot group, their distribution was disordered and failed to form intact lumen. There were less vascular endothelial cells in wounds of pressure ulcer group than those of diabetic foot group, but the complete lumen was formed. (3) The mRNA expression levels of VEGF192 in wounds of burn wound group, pressure ulcer group, and diabetic foot group were significantly lower than the level in normal skin group (H=13.72, 30.50, 15.20, P<0.05 or P<0.01), and the level was the lowest in pressure ulcer group. The mRNA expression level of VEGF192 in wounds of pressure ulcer group was significantly lower than that of diabetic foot group (H=15.30, P<0.01). Compared with that of normal skin group, the mRNA expression level of TGF-β in wounds of burn wound group showed no significant difference (H=-9.50, P>0.05), while the mRNA expression levels of TGF-β in wounds of pressure ulcer group and diabetic foot group were significantly decreased (H=18.04, 14.50, P<0.01). The mRNA expression level of TGF-β in wounds of pressure ulcer group was similar to that of diabetic foot group (H=3.54, P>0.05). (4) Compared with those of normal skin group, the mRNA expression levels of VCAM-1 in wounds of burn wound group and pressure ulcer group were significantly increased (H=-22.50, -11.50, P<0.05 or P<0.01), and there was no significant difference in the mRNA expression level of VCAM-1 in wounds of diabetic foot group (H=10.00, P>0.05); the mRNA expression level of ICAM-1 in wounds of burn wound group showed no significant difference (H=-9.50, P>0.05), and the levels of ICAM-1 in wounds of pressure ulcer group and diabetic foot group were significantly decreased (H=16.50, 16.50, P<0.01). The mRNA expression level of VCAM-1 in wounds of pressure ulcer group was significantly higher than that of diabetic foot group (H=-21.50, P<0.01), the mRNA expression level of ICAM-1 in wounds of pressure ulcer group was similar to that of diabetic foot group (H=0, P>0.05). (5) Compared with those of normal skin group, except for the mRNA expression level of IL-1β in wounds of diabetic foot group showed no significant difference (H=-10.00, P>0.05), the mRNA expression levels of IL-1β in wounds of burn wound group and pressure ulcer group were significantly increased (H=-32.50, -21.50, P<0.01); the mRNA expression levels of IL-6 were significantly increased in wounds of burn wound group, pressure ulcer group, and diabetic foot group (H=-17.50, -30.50, -11.80, P<0.05 or P<0.01); except for the mRNA expression level of TNF-α in wounds of burn wound group showed no significant difference (H=-9.50, P>0.05), the mRNA expression levels of TNF-α in wounds of pressure ulcer group and diabetic foot group were significantly decreased (H=18.04, 14.50, P<0.01). The mRNA expression levels of IL-1β and TNF-α in wounds of pressure ulcer group were significantly lower than those of burn wound group (H=11.00, 27.54, P<0.05 or P<0.01), while the mRNA expression level of IL-6 was significantly higher (H=-13.00, P<0.05). The mRNA expression levels of IL-1β and TNF-α in wounds of diabetic foot group were significantly lower than those of burn wound group (H=22.50, 24.00, P<0.01), while the mRNA expression level of IL-6 showed no significant difference (H=5.70, P>0.05).@*Conclusions@#The phenotypes of diabetic foot and pressure ulcer vary from the expressions levels of proliferating cell nuclear antigen and blood vessels forming ability to the expression levels of growth factors, cell adhesion factors, and inflammatory cytokines.

Effects of aerosol inhalation of recombinant human keratinocyte growth factor 2 on the lung tissue of rabbits with severe smoke inhalation injury / 中华烧伤杂志

Objective@#To investigate the effect of recombinant human keratinocyte growth factor 2 (rhKGF-2) on lung tissue of rabbits with severe smoke inhalation injury.@*Methods@#A total of 120 New Zealand rabbits were divided into 5 groups by random number table after being inflicted with severe smoke inhalation injury, with 24 rats in each group. Rabbits in the simple injury group inhaled air, while rabbits in the injury+phosphate buffer solution (PBS) group inhaled 5 mL PBS once daily for 7 d. Rabbits in injury+1 mg/kg rhKGF-2 group, injury+2 mg/kg rhKGF-2 group, and injury+5 mg/kg rhKGF-2 group received aerosol inhalation of 1 mg/kg, 2 mg/kg, and 5 mg/kg rhKGF-2 (all dissolved in 5 mL PBS) once daily for 7 d, respectively. On treatment day 1, 3, 5, and 7, blood samples were taken from the ear central artery of 6 rabbits in each group. After the blood was taken, the rabbits were sacrificed, and the tracheal carina tissue and lung were collected. Blood pH value, arterial oxygen partial pressure (PaO2), arterial blood carbon dioxide pressure (PaCO2), and bicarbonate ion were detected by handheld blood analyzer. The expressions of pulmonary surfactant-associated protein A (SP-A) and vascular endothelial growth factor (VEGF) in lung tissue were detected by Western blotting. Pathomorphology of lung tissue and trachea was observed by hematoxylin-eosin staining. Data were processed with analysis of variance of two-way factorial design and Tukey test.@*Results@#(1) Compared with those in simple injury group, the blood pH values of rabbits in the latter groups on treatment day 1-7 had no obvious change (P>0.05). The PaO2 of rabbits in injury+2 mg/kg rhKGF-2 group on treatment day 5 and 7 were (75.0±2.4) and (71.0±4.5) mmHg (1 mmHg=0.133 kPa), respectively, which were significantly higher than (62.0±6.8) and (63.0±3.0) mmHg in simple injury group (q=4.265, 8.202, P<0.05 or P<0.01). The PaO2 of rabbits in injury+5 mg/kg rhKGF-2 group on treatment day 7 was (82.0±4.9) mmHg, which was significantly higher than that in simple injury group (q=6.234, P<0.01). Compared with that in simple injury group, the PaCO2 of rabbits in injury+2 mg/kg rhKGF-2 group on treatment day 3 was significantly decreased (q=4.876, P<0.01) and significantly increased on treatment day 5 (q=5.562, P<0.01); the PaCO2 of rabbits in injury+5 mg/kg rhKGF-2 group was significantly increased on treatment day 5 and 7 (q=5.013, 4.601, P<0.05 or P<0.01). Compared with that in simple injury group, the serum bicarbonate ion of rabbits in injury+1 mg/kg rhKGF-2 group on treatment day 7 was significantly increased (q=5.142, P<0.01); the serum bicarbonate ion of rabbits in injury+2 mg/kg rhKGF-2 group on treatment day 5 and 7 were significantly increased (q=4.830, 6.934, P<0.01); the serum bicarbonate ion of rabbits in injury+5 mg/kg rhKGF-2 group on treatment day 5 were significantly increased (q=3.973, P<0.05). (2) The expressions of SP-A in lung tissue of rabbits in simple injury group and injury+PBS group in each treatment time point were close (P>0.05). The expressions of SP-A in lung tissue of rabbits in injury+2 mg/kg rhKGF-2 group and injury+5 mg/kg rhKGF-2 group on treatment day 3 were 0.091±0.007 and 0.101±0.009, respectively, significantly higher than 0.069±0.009 in simple injury group (q=10.800, 13.580, P<0.01). The expressions of SP-A in lung tissue of rabbits in injury+1 mg/kg rhKGF-2 group, injury+2 mg/kg rhKGF-2 group, and injury+5 mg/kg rhKGF-2 group on treatment day 5 and 7 were 0.127±0.008, 0.132±0.006, 0.194±0.006, 0.152±0.017, 0.166±0.004, 0.240±0.008, significantly higher than 0.092±0.003 and 0.108±0.005 in simple injury group (q=6.789, 12.340, 17.900, 9.875, 31.480, 40.740, P<0.01). (3) On treatment day 1 and 5, there was no significant difference in the expression of VEGF in lung tissue of rabbits among the 5 groups (P>0.05). Compared with those in simple injury group, the expressions of VEGF in lung tissue of rabbits in injury+2 mg/kg rhKGF-2 group on treatment day 3 and 7 were significantly increased (q=4.243, 8.000, P<0.05 or P<0.01), and the expression of VEGF in lung tissue of rabbits in injury+5 mg/kg rhKGF-2 group on treatment day 7 was significantly increased (q=20.720, P<0.01). (4) On treatment day 1, the injury of rabbits in each group was similar, with a large number of neutrophils infiltrated and abscess formed in the alveolar and interstitial tissue, thickened alveolar septum, some collapsed alveolar and atelectasis; large area of tracheal mucosa was degenerated and necrotic, with a large amount of inflammatory exudates blocking in the cavity. On treatment day 3, the inflammation of lung tissue and trachea in each group were improved, but the inflammation in simple injury group and injury+PBS group was also serious. On treatment day 5, the inflammation in lung tissue and trachea of rabbits in injury+2 mg/kg rhKGF-2 group and injury+5 mg/kg rhKGF-2 group were improved much obviously than those in the other groups. On treatment day 7, the inflammation in lung tissue of rabbits in injury+5 mg/kg rhKGF-2 group alleviated obviously than those in the other groups, most alveoli had no obvious exudative fluid, the alveolar cavity was intact and clear, the local alveolar dilated like a cyst, and the alveolar septum thinning; the improvement of inflammation of trachea was more obvious than the other groups, the tracheal mucosa tended to be more complete, and few neutrophils were infiltrated in the endotracheal cavity.@*Conclusions@#Atomization inhalation of rhKGF-2 can improve the PaO2 level of rabbits with severe smoke inhalation injury, reduce airway inflammation, increase the expression of SP-A and VEGF in lung tissue, thus promoting the repair of lung tissue.

Effect of lung protective ventilation strategy on oxygenation and pulmonary inflammatory response in dogs with severe smoke inhalation injury / 中国中西医结合急救杂志

Objective To observe the effect of lung protective ventilation strategy on oxygenation and pulmonary inflammatory response in dogs with severe smoke inhalation injury.Methods Twelve local healthy male dogs were selected and anesthetized underwent endotracheal intubation, the time controlled smoke was applied to replicate the model of severe smoke inhalation injury, and they were divided into two groups according to the random number table: conventional ventilation group (CV group) and protective ventilation group (PV group), each receiving corresponding ventilation mode for 8 hours respectively. The blood gas analyses were detected before injury, immediately after injury and at ventilation for 2, 4, 6, 8 hours. The contents of tumor necrosis factor-α (TNF-α), interleukin-10 (IL-10) in serum were detected by the enzyme-linked immunosorbent assay (ELISA) at each time point. Animals were killed after 8-hour ventilation, and different parts of the lung tissues were obtained for pathological examinations of lung tissues and evaluation of injury scores. The levels of inflammatory factors as TNF-α and IL-10 in lung homogenates were measured by ELISA.Results The arterial partial pressure (PaO2) levels in CV and PV groups were significantly decreased after injury compared with those before injury [mmHg (1 mmHg = 0.133 kPa): 57±19 vs. 128±31, 58±15 vs. 126±22, bothP 0.05). At 6 hours ventilation, PaO2 level in PV group was significantly higher than that in CV group (mmHg: 121±11 vs. 105±11,P 0.05). The histopathological changes revealed that there were alveolar tissue edema and inflammatory cells infiltration in both groups, the degree of severity in CV group was more prominent and its pulmonary tissue injury score was higher than that in PV group (3.68±0.22 vs. 3.27±0.35, P < 0.05). The serum levels of TNF-α and IL-10 after smoke injury were significantly increased in CV and PV groups [TNF-α (μg/L): 4.32±1.13 vs. 0.35±0.11, 4.51±2.02 vs. 0.41±0.08; IL-10 (ng/L): 16.73±2.31 vs. 4.27±0.56, 18.39±3.15 vs. 4.03±1.07, allP < 0.01]. Compared with CV group, the levels of TNF-α were significantly lower at 6 hours and 8 hours of ventilation [6 hours (μg/L): 2.62±0.34 vs. 3.65±1.08, 8 hours (μg/L): 3.02±0.31 vs. 4.21±1.27, bothP < 0.05), while the contents of IL-10 were obviously increased in PV group [6 hours (ng/L): 21.07±2.95 vs. 16.11±3.02, 8 hours (ng/L): 23.57±2.69 vs. 18.28±3.21, bothP < 0.05]. The content of TNF-α in lung homogenate in CV group was significantly higher than that in PV group (μg/L: 5.85±2.57 vs. 3.08±1.17,P < 0.05), but the content of IL-10 in lung homogenate of CV group was markedly lower than that in CP group (ng/L: 19.64±3.16 vs. 24.05±2.09, P < 0.05).Conclusion Lung protective ventilation strategy can effectively improve oxygenation and pulmonary inflammatory response in dogs with severe smoke inhalation injury, thus the lung injury is alleviated and the strategy has protective effect on damaged lung tissues.

Effects of high frequency oscillatory ventilation combined with incremental positive end-expiratory pressure on myocardial ischemia and hypoxia and apoptosis of cardiomyocytes in dogs with smoke inhalation injury / 中华烧伤杂志

<p><b>OBJECTIVE</b>To compare the effects of high frequency oscillatory ventilation (HFOV) combined with incremental positive end-expiratory pressure (IP) and those of pure HFOV on myocardial ischemia and hypoxia and apoptosis of cardiomyocytes in dogs with smoke inhalation injury.</p><p><b>METHODS</b>Twelve healthy male dogs were divided into group HFOV and group HFOV+IP according to the random number table, with 6 dogs in each group. After being treated with conventional mechanical ventilation, dogs in both groups were inflicted with severe smoke inhalation injury, and then they received corresponding ventilation for 8 hours respectively. After treatment, the blood samples were collected from heart to determine the activity of creatine kinase-MB (CK-MB) and lactate dehydrogenase 1 (LDH1) in plasma. The dogs were sacrificed later. Myocardium was obtained for determination of content of TNF-α per gram myocardium by ELISA, apoptotic rate of cardiomyocytes by flow cytometer, degree of hypoxia with HE staining, and qualitative and quantitative expression of actin (denoted as integral absorbance value) with streptavidin-biotin-peroxidase staining. Data were processed with t test. The relationship between the content of TNF-α per gram myocardium and the apoptotic rate of cardiomyocytes was assessed by Spearman linear correlation analysis.</p><p><b>RESULTS</b>(1) After treatment for 8 h, the values of activity of CK-MB and LDH1 in plasma of dogs in group HFOV+IP were respectively (734 ± 70) and (182 ± 15) U/L, which were both lower than those in group HFOV [(831 ± 79) and (203 ± 16) U/L, with t values respectively 2.25 and 2.35, P values below 0.05]. (2) Compared with that in group HFOV [(0.060 ± 0.018) µg], the content of TNF-α per gram myocardium of dogs in group HFOV+IP after treatment for 8 h was decreased significantly [(0.040 ± 0.011) µg, t=2.32, P<0.05]. (3) Compared with that in group HFOV [(33.4 ± 2.2)%], the apoptotic rate of cardiomyocytes of dogs in group HFOV+IP after treatment for 8 h was significantly decreased [(28.2 ± 3.4)%, t=3.15, P<0.05]. There was a positive correlation between the content of TNF-α per gram myocardium and the apoptotic rate of cardiomyocytes (r=0.677, P<0.05). (4) HE staining showed that myocardial fibers of dogs in both groups were arranged in wave shape in different degrees, indicating there was myocardial hypoxia in different degrees. Compared with that of group HFOV, the degree of hypoxia in group HFOV+IP was slighter. (5) The results of immunohistochemical staining showed that there was less loss of actin in myocardial fibers of dogs in group HFOV+IP than in group HFOV. The expression level of actin in myocardium of dogs in group HFOV+IP after treatment for 8 h (194.7 ± 3.1) was obviously higher than that in group HFOV (172.9 ± 2.6, t=13.20, P<0.01).</p><p><b>CONCLUSIONS</b>Compared with pure HFOV, HFOV combined with IP can alleviate the inflammatory reaction in myocardium of dogs, reduce the apoptosis of cardiomyocytes, and ameliorate the myocardial damage due to ischemia and hypoxia.</p>

Effects of different position during high frequency oscillatory ventilation on oxygenation and hemodynamics of dogs with severe smoke inhalation injury / 中华烧伤杂志

<p><b>OBJECTIVE</b>To study the effects of high frequency oscillatory ventilation (HFOV) with different position on oxygenation and hemodynamics of dogs with severe smoke inhalation injury.</p><p><b>METHODS</b>After being treated with conventional mechanical ventilation, 12 dogs were inflicted with severe smoke inhalation injury and treated by HFOV for 30 min. They were divided into HFOV+prone positioning (PP) group and HFOV+supine positioning (SP) group according to the random number table, with 6 dogs in each group. They received HFOV with corresponding position for 8 hours respectively.</p><p><b>RESULTS</b>of blood gas analysis (pH, PaO₂ and PaCO₂ levels), oxygen index (OI) and hemodynamic parameters [heart rate, mean arterial pressure (MAP), and cardiac output (CO)] were recorded or calculated before injury, immediately after injury, and at post ventilation hour (PVH) 2, 4, 6, 8. Data were processed with analysis of variance of repeated measurement, and LSD- t test.</p><p><b>RESULTS</b>(1) At PVH 8, pH value of dogs in group HFOV+PP was significantly higher than that in group HFOV+SP (t = 3.0571, P < 0.05). Compared with those observed immediately after injury, except for group HFOV+SP at PVH 2 and 4 (with t values respectively 2.066 5 and 1.440 7, P values all above 0.05), the pH values in both groups at other treatment time points were decreased (with t values from 2.449 5 to 3.985 3, P < 0.05 or P < 0.01). At PVH 2, 4, 8, the PaO₂ levels in group HFOV+PP [(131 ± 26), (150 ± 40), (112 ± 30) mmHg, 1 mmHg = 0.133 kPa] were higher than those in group HFOV+SP [(81 ± 15), (96 ± 5), (83 ± 6) mmHg, with t values from 2.366 4 to 4.083 5, P < 0.05 or P < 0.01]. The PaO₂ levels in both groups from PVH 2 to PVH 8 were increased, compared with those observed immediately after injury [(55 ± 15) mmHg in group HFOV+SP and (48 ± 11) mmHg in group HFOV+PP, with t values from 2.473 6 to 7.2310, P < 0.05 or P < 0.01]. No statistically significant differences were observed in PaCO₂ level at each time point between two groups (with t values from 0.661 0 to 2.141 9, P values all above 0.05). No statistically significant differences were observed in PaCO₂ levels from PVH 2 to PVH 8 compared with those observed immediately after injury in both groups (with t values from 0.126 2 to 1.768 3, P values all above 0.05). (2) The OI values in group HFOV+SP were significantly higher than those in group HFOV+PP from PVH 2 to PVH 8 (with t values from 3.091 9 to 3.791 6, P < 0.05 or P < 0.01). The OI values in both groups from PVH 2 to PVH 8 were significantly decreased, compared with those observed immediately after injury (with t values from 2.702 0 to 5.969 3, P < 0.05 or P < 0.01). (3) At PVH 6 and PVH 8, heart rate in group HFOV+PP was significantly higher than that in group HFOV+SP (with t values respectively 4.255 9 and 4.765 9, P values both below 0.01). Compared with that observed immediately after injury, heart rate in group HFOV+PP was significantly decreased (with t values from 3.006 2 to 5.135 5, P < 0.05 or P < 0.01) except for PVH 2 (t = 1.938 2, P > 0.05). However, there was no statistical significant difference at each treatment time point in group HFOV+PP (with t values from 0.786 5 to 1.525 8, P values all above 0.05). There was no statistically significant difference in MAP between two groups at each time point (with t values from 0.045 8 to 1.783 4, P values all above 0.05). Compared with that observed immediately after injury, MAP in group HFOV+SP was significantly decreased at PVH 8 (t = 2.368 3, P < 0.05); MAP in group HFOV+PP was significantly decreased at PVH 2 (t = 3.580 1, P < 0.01). At PVH 2 and 4, the CO values in group HFOV+SP were significantly higher than those in group HFOV+PP (with t values respectively 2.310 3 and 4.526 5, P values both below 0.01). Except for group HFOV+SP at PVH 2 (t = 1.294 1, P > 0.05), CO values at other treatment time points in both groups were significantly lower than that observed immediately after injury (with t values from 2.247 0 to 4.067 8, P < 0.05 or P < 0.01).</p><p><b>CONCLUSIONS</b>HFOV+ PP can improve oxygenation with no obvious CO₂ retention or adverse effect on hemodynamic parameters of dogs with severe smoke inhalation injury. Therefore, it is recommended for clinical application.</p>

Effects of two kinds of lung recruitment maneuvers on the correlated indexes of dogs with severe smoke inhalation injury / 中华烧伤杂志

<p><b>OBJECTIVE</b>To observe and compare the effects of two kinds of lung recruitment maneuvers, namely sustained inflation (SI) and incremental positive end-expiratory pressure (PEEP) (IP) on oxygenation, respiratory mechanics, and hemodynamics of dogs with severe smoke inhalation injury.</p><p><b>METHODS</b>After being treated with conventional mechanical ventilation, 12 dogs were inflicted with severe smoke inhalation injury. They were divided into group SI and group IP according to the random number table, with 6 dogs in each group. Dogs in group SI were subjected to continuous positive airway pressure ventilation, with inspiratory pressure of 25 cmH2O (1 cmH2o = 0. 098 kPa), and it was sustained for 20 s. PEEP level in group IP was gradually increased by 5 cmH2O every 5 min up to 25 cmH2O, and then it was decreased by 5 cmH2O every 5 min until reaching 2-3 cmH2O. Then the previous ventilation mode was resumed in both groups for 8 hours. Blood gas analysis (pH value, PaO2, and PaCO2), oxygenation index (OI), respiratory mechanics parameters [peak inspiratory pressure (PIP), mean airway pressure, and dynamic lung compliance], and hemodynamic parameters [heart rate, mean arterial pressure (MAP), pulmonary arterial pressure (PAP), and cardiac output (CO)] were recorded or calculated before injury, immediately after injury, and at post ventilation hour (PVH) 2, 4, 6, 8. Data were processed with analysis of variance of repeated measurement and LSD-t test.</p><p><b>RESULTS</b>(1) At PVH 6 and 8, pH values of dogs in group SI were significantly lower than those in group IP (with t values respectively 2. 431 and 2. 261, P values below 0.05); PaO2 levels in group SI [(87 ± 24), (78 ± 14) mmHg, 1 mmHg =0. 133 kPa] were lower than those in group IP [ (114 ± 18) , (111 ± 17) mmHg, with t values respectively 2. 249 and 3.671, P <0.05 or P <0.01]; OI values in group SI were significantly higher than those in group IP (with t values respectively 2.363 and 5.010, P <0.05 or P <0.01). No significant differences were observed in PaCO2 level within each group or between the two groups (with t values from 0. 119 to 1. 042, P values above 0.05). Compared with those observed immediately after injury, the pH values were significantly lowered (except for dogs in group IP at PVH 6 and 8, with t values from 2.292 to 3.222, P <0.05 or P <0.01), PaO2 levels were significantly elevated (with t values from 4. 443 to 6.315, P <0.05 or P <0.01), and OI values were significantly lowered (with t values from 2.773 to 9.789, P <0.05 orP <0.01) in both groups at all the treatment time points. (2) The PIP level at each time point showed no significant differences between two groups (with t values from 0. 399 to 1. 167, P values above 0. 05). At PVH 4 and 8, the mean airway .pressure values of dogs in group SI were significantly higher than those in group IP (with t values respectively 1.926 and 1. 190, P values below 0.05). At PVH 4, 6, and 8, the dynamic lung compliance levels of dogs in group SI [(9.5 ± 1.9), (12.8 ± 2. 1), (13. 1 ± 1.8) mL/cmH2O] were significantly lower than those in group IP [(11.6 ± 1.2), (15.4 ± 1.8), (14.9 ± 0.8) mL/cmH2O], with t values respectively 2. 289, 2. 303, 2. 238, P values below 0.05. Compared with those observed immediately after injury, PIP and the mean airway pressure values of dogs in two groups were significantly lowered at each treatment time point (with t values from 2. 271 to 7. 436, P <0. 05 or P < 0.01); the dynamic lung compliance levels were significantly elevated in both groups at PVH 6 and 8 (with t values from 2. 207 to 4. 195, P < 0.05 or P <0.01). (3) Heart rate, MAP, and PAP levels at each time point between two groups showed no significant differences (with t values from 0. 001 to 1. 170, P values above 0. 05). At PVH 4, 6, and 8, CO levels in group IP [(0. 6 + 0. 3), (0. 6 + 0. 4), (0. 5 + 0. 7) L/min] were significantly lower than those in group SI [(1.5 0.7), (1.8 + 1.1), (1.6 +0.9) L/min], with t values respectively 3. 028, 2.511, 2.363, P values below 0.05. Compared with that observed immediately after injury, CO level in group IP was significantly lowered at PVH 4, 6, or 8 (with t values respectively 2. 363, 2. 302, 2. 254, P values below 0. 05).</p><p><b>CONCLUSIONS</b>Both lung recruitment maneuvers can effectively improve oxygenation and lung compliance of dogs with severe smoke inhalation injury. IP is more effective in improving lung compliance, while SI shows less impact on the hemodynamic parameters.</p>