Objective To study the characteristics of its pathologic and neurophysiologic changes of a ani-mal model of cervical spinal cord compression, and to explore the relationship between the severity of spinal cord inju-ry and its functions. Methods Thirty-two rabbits were divided into 4 groups randomly. A catheter was inserted intothe vertebral canal and a balloon was inflated to compress spinal cord in epidural space. According to the diameter ofballoon, the animals were divided into 4 groups (A, B, C, D group), Each group consisted of 8 rabbits. The corti-cal somatosensory evoked potential (CSEP) and motor evoked potential (MEP) were used to assess neurologicalfunction. Motor function behavior was scored before and on 1, 3, 7 and 14 days after surgery. Histological observa-tions were performed, pathological changes were observed by light and electron microscope. Results Spinal cordcompression resulted in a gradual increase of the peak latency and significant decrease of the peak amplitude. The la-tency and amplitude of MEP were changed more dramatically than those of CSEP. The result indicated that MEP wasmore sensitive than CSEP to the compression. Analysis also revealed that the severer the pathologic changes, the lon-ger the latency and the lower the amplitude of the evoked potentials. Conclusion The animal model presented inthis paper was simple and standardized. Evoked potentials as a noninvasive technique have great value in monitoringspinal cord function. The variance of amplitude and the latency in significantly correlate with the degree of compres-sion of the spinal cord.

OBJECTIVETo 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.

METHODSAfter 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.

RESULTS(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).

CONCLUSIONSBoth 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.

Animals ; Blood Gas Analysis ; veterinary ; Dogs ; Hemodynamics ; Lung Compliance ; physiology ; Oxygen ; blood ; Oxygen Consumption ; physiology ; Positive-Pressure Respiration ; methods ; Respiration, Artificial ; Respiratory Mechanics ; Severity of Illness Index ; Smoke ; adverse effects ; Smoke Inhalation Injury ; physiopathology ; therapy

Objective To analyze the causes and manifestations of non-pulmonary embolism induced perfusion defects (PDs) on dual-energy perfusion imaging (DEPI) using dual source CT.Methods Consecutive 208 patients without pulmonary embolism who underwent DEPI were reviewed retrospectively.The causes of PDs were analyzed by two radiologists, the pulmonary segment numbers, the proportion and the perfusion patterns of each case were recorded and analyzed respectively.Results 1 118 of 3 716 pulmonary segments showed the PDs.Among them, 752(67.26%), 36(3.22%), 308(27.55%) and 22(1.97%) pulmonary segments had PDs due to intra-pulmonary lesions, vascular diseases, artifacts and unidentifiable causes, respectively.In PDs resulted from intra-pulmonary lesions, vascular diseases and unidentifiable causes, three patterns (wedge-shaped, heterogeneous and regionally homogeneous) were identified,and most of those PDs were heterogeneous and regionally homogeneous, which were largely in accordance with the lesions showed on non-contrast enhanced scans.Artifacts included the beam hardening artifacts and artifacts caused by heart beat or diaphragmatic movement.The PDs caused by artifacts usually had particular locations and shapes.Conclusion Understanding of the manifestations and causes of PDs in patients without pulmonary embolism can improve the diagnosis accuracy of pulmonary embolism on DEPI.

Objective To evaluate the bioequivalence of two formulations of minocycline hydrochloride capsules administered orally after fasting administration and fed administration.Methods An open-label,randomized,two-period,self-crossover design was employed to assess the bioequivalence study.Twenty-eight healthy subjects were enrolled in both fasting and fed groups,with each period involving a single administration of either the reference formulation or the test formulation of 50 mg,separated by a washout period of 7 days.The concentration of minocycline in human plasma was determined by HPLC-MS/MS and was used for calculating pharmacokinetic parameters and evaluating the bioequivalence of the test formulation and reference formulation.Results After oral administration of test and reference formulations of minocycline under fasting condition,the Cmax Values of minocycline were(541±137)ng·mL-1 for the test formulation and(558±140)ng·mL-1for the reference formulation.The AUC0-t values were(8 347±1 986)h·ng·mL-1 for the test and(8 205±1 790)h·ng·mL-1 for the reference.The t1/2 values were(18.2±2.84)h for the test and(18.0±3.05)h for the reference.After oral administration of the test and reference formulations of minocycline under fed condition,the Cmax values of minocycline were(349±72.1)ng·mL-1 for the test and(352±73.2)ng·mL-1for the reference.The AUC0-twere(6 428±1 077)h·ng·mL-1 for the test and(6 588±1 118)h·ng·mL-1 for the reference.The t1/2values were(18.5±3.10)h for the test and(18.4±3.21)h for the reference.Under fasting condition,the 90% confidence intervals for the geometric mean ratios of Cmax,AUC0-t,and AUC0-∞ between the test and reference formulations were(90.84%,101.46% ),(95.2%,102.8% ),and(95.31%,102.71% ),respectively.Under fed conditions,the 90% confidence intervals for the geometric mean ratios of Cmax,AUC0-t,and AUC0-∞ between the test formulation and the reference formulation were(94.71%,103.42% ),(95.40%,99.83% ),and(95.79%,100.02% ),respectively.Conclusions Bioequivalence of the two minocycline formulations was demonstrated after fasting administration and fed administration in a healthy Chinese population.

OBJECTIVETo 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.

METHODSTwelve 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.

RESULTS(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).

CONCLUSIONSCompared 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.

Animals ; Apoptosis ; physiology ; Burns, Inhalation ; physiopathology ; therapy ; Dogs ; High-Frequency Ventilation ; Hypoxia ; Male ; Myocardial Ischemia ; physiopathology ; Myocytes, Cardiac ; Positive-Pressure Respiration ; Respiration, Artificial ; Smoke ; adverse effects ; Smoke Inhalation Injury ; therapy ; Treatment Outcome ; Tumor Necrosis Factor-alpha

OBJECTIVETo study the effects of high frequency oscillatory ventilation (HFOV) with different position on oxygenation and hemodynamics of dogs with severe smoke inhalation injury.

METHODSAfter 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.

RESULTSof 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.

RESULTS(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).

CONCLUSIONSHFOV+ 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.

Animals ; Carbon Dioxide ; blood ; Disease Models, Animal ; Dogs ; Hemodynamics ; High-Frequency Ventilation ; Male ; Oxygen ; blood ; Prone Position ; Smoke Inhalation Injury ; physiopathology ; therapy ; Supine Position