[Effects of different fluid resuscitation methods on hemorheology in pigs during burn shock stage].

Objective: To investigate the impact of different methods of fluid resuscitation on hemorheology during burn shock stage. Methods: Twenty four miniature swines were randomly divided into four groups with 6 in each group (succinylated gelatin group, hydroxyethyl starch group, Parkland group and allogeneic plasma group). Severe burn shock model was established by burning miniature swine with napalm. Two hours after injury, succinylated gelatin, hydroxyethyl starch (130/0.4) and swine allogenic plasma were used as colloid (alternative colloid) in fluid resuscitation according to the burn shock fluid resuscitation formula which is commonly accepted in the field of Burns Surgery. In Parkland group, miniature swines received liquid recovery according to Parkland Formula. The vital signs before and within 48 h after burn were observed by Solar 8000i electrocardiomonitor during the process of transfusion. The infusion speed was adjusted based on the heart rate, blood pressure, urine volume and central venous pressure. The level of hematocrit (HCT), viscosity of plasma (ηp), index of rigidity (IR), red cell assembling index (RCA) and erythrocyte electrophoresis time (EFT) were measured at the time of pre-injury as well as 4, 8, 24 and 48 h post-injury and statistical analysis was performed. Results: HCT in hydroxyethyl starch group and Parkland group at 8 h post-injury were significantly higher than pre-injury [(0.395±0.047) vs (0.333±0.042), (0.379±0.026) vs (0.352±0.019)] (both P<0.05). And compared with pre-injury, HCT in hydroxyethyl starch (130/0.4) group at 48 h decreased significantly (0.232±0.021) vs (0.333±0.042) (P<0.05). HCT in Parkland group at 24, 48 h post-injury were lower than pre-injury [(0.277±0.021), (0.241±0.029) vs (0.352±0.019)] (both P<0.05). Compared with pre-injury, the levels of ηp in Parkland group decreased substantially at 4, 8 and 24 h post-injury [(1.61±0.07), (1.55±0.07) and (1.63±0.07) vs (1.73±0.04) mPa·s] (all P<0.05). Compared with allogeneic plasma group, IR decreased in succinylated gelatin group at 24, 48 h post-injury [(1.10±0.05 vs 1.26±0.07), (1.11±0.05 vs 1.32±0.05)](both P<0.05). RCA in succinylated gelatin group was significantly higher (both P<0.05) at 4 h (6.80±0.87) than pre-injury (5.92±0.43). RCA in hydroxyethyl starch group at 8 h post-injury (6.73±0.56) was significantly higher (both P<0.05) than pre-injury (6.03±0.53). Compared with pre-injury (17.3±1.3 s, 16.4±1.5 s), the levels of EFT in hydroxyethyl starch group (15.5±1.4 s) and Parkland group (13.4±1.2 s) decreased substantially at 48 h post-injury (both P<0.05). Compared with allogeneic plasma group, the level of EFT in succinylated gelatin group at 4 h post-injury (19.5±2.3 s) increased and decreased at 24 h post-injury (12.0±5.7 s) (both P<0.05). Conclusion: During swine burn shock stage, the hemorheological parameters of shock resuscitation with artificial colloid are more stable than those with Parkland formula resuscitation.

[Effects of resuscitation by different formulation on oxygen metabolism during shock stage of burn injury in swine].

OBJECTIVE: To explore the effects of different fluid resuscitation regimens on oxygen metabolism during shock stage of burn injury in swine. METHODS: Twelve Bama miniature swines were divided into crystal and colloid group (Group 1) and Parkland group (Group 2) according to the random number table. The swine models of burns shock were established. The fluid resuscitation was begun at post injury hour (PIH) 2 according to Chinese formulation or Parkland's formulation, respectively. The blood pressure, urine volume, heart rate, central venous pressure (CVP), pulmonary capillary wedge pressure (PCWP) were recorded. The liquid volume was calculated at the first and second PIH 24. The changes in oxygen delivery (DO2), oxygen consumption (VO2), oxygen extraction (O2Ext) and D-lactate (D-LA) were determined before injury and at PIH 4, 8, 24, and 48. Statistical analyses were performed. RESULTS: There were no statistical differences between the two groups in blood pressure, urine volume, heart rate, CVP, PCWP in every interval (all P>0.05). The resuscitation liquid volume in the two groups during the first and second PIH 24 conformed to the domestic consensus. The VO2 at PIH 8 was significantly higher than that of pre-burn in both groups [(190±29) vs (83±42) L·min(-1)·m(-2,) (149±33) vs (85±15) L·min(-1)·m(-2,) both P<0.05], and the VO2 at PIH 8 was significantly higher in Group 1 than that in Group 2 (P<0.05). The DO2 at PIH 24 in Group 1 was significantly lower than that in Group 2 [(686±72) vs (853±81) L·min(-1)·m(-2,) P<0.05]. There were no significant differences between the two groups in O2Ext at any time points (all P>0.05). The D-LA at PIH 8 was significantly higher in Group 1 than that in Group 2 [(53±4) vs (45±6) mmol/L, P<0.05]. CONCLUSION: There are no significant differences in the resuscitation effects of the crystal and colloid resuscitation regimen and Parkland's formulation on oxygen metabolism during shock stage of burn injury in swine.

[Effects on wound bed of deep burn following eschar excision with different wound management in rabbits].

OBJECTIVE: To compare the effects on wound bed of deep burn following eschar excision with different wound management in rabbits. METHODS: Eighteen full-thickness burns models of Japanese white rabbits were established. They were randomly divided into 3 groups of traditional dressing, biological dressing and negative pressure wound therapy (NPWT) (n=6 each), according to the random number table. Eschar excision was performed three days later. The wound bed was observed and wound tissue was harvested for counting the quantity of bacteria, tissue dry wet ratio, measuring the level of tumor necrosis factor alpha (TNF-α), interleukin (IL)-1ß and IL-6, the amount of collagen fibers and the microvessel density instantly and again seven days later. Statistical analyses were performed. RESULTS: The NPWT group was better than other groups by observing the wound bed. The quantity of bacteria of traditional dressing group, biological dressing group and NPWT group at the time point of seven days after escharectomy turned out to be (9.4±1.5)×10(4,) (8.1±2.7)×10(4,) (3.9±0.7)×10(4) cfu/g, the NPWT group was significantly lower than traditional dressing group and biological dressing group (both P<0.05), and all lower than that at the time point of the day when escharectomy was performed (576.9±169.5)×10(4,) (589.9±99.6)×10(4,) (583.0±160.4)×10(4) cfu/g ( all P<0.05). There were no statistically significant differences among three groups at two time points in tissue dry wet ratio (all P>0.05). The IL-6 of biological dressing group was higher than that of traditional dressing group at the time point of seven days after the eschar excision was performed[(94±10) vs (76±8) ng/L, P<0.05]. The amount of collagen fibers of three group at the time point of seven days after escharectomy turned out to be (60±9), (55±12), (77±17). The NPWT group was significantly higher than traditional dressing group and biological dressing group (P<0.05), and all higher than that at the time point of the day when escharectomy was performed[(39±6), (39±11), (38±6)](all P<0.05). The microvessel density of three groups at the time point of seven days after escharectomy turned out to be (42±6), (53±4), (82±10). The NPWT group was higher than that of the other two groups, and biological dressing group was higher than that of traditional dressing group (all P<0.05). The biological dressing group and NPWT group were both higher than that of the day when the eschar excision was performed (36±5) and (36±5) (P<0.05). CONCLUSIONS: NPWT is the optimal selection for wound to inhibit the growth of bacteria, promote the accumulation of collagen and tissue vascularization. But these managements have similar effects on reducing tissue edema and inflammatory reaction.

[One case of extremely severe burn combined with stillbirth and multiple organ dysfunction syndrome in the third trimester of pregnancy].

One 24 years old female patient who suffered extremely severe burn in the third trimester of pregnancy was admitted to the Department of Burns and Skin Repair Surgery of the Third Affiliated Hospital of Wenzhou Medical University on 9th May, 2015. Intrauterine distress occurred after injury and stillbirth was confirmed within 12 hours. In cooperation with the obstetrician, the labor was induced on post injury day (PID) 5. Septic shock and multiple organ dysfunction syndrome occurred on PID 8. Through treatments including anti-infection, ventilator-assisted ventilation, cardiotonic diuresis, and escharectomy and skin grafting, the patient was finally cured. This case indicates that it is crucial to grasp the right time and choose a reasonable induction of labor to deal with stillbirth. The scheme of transvaginal induction of labor after shock is a worthy question to explore. The main characteristics of this patient include the extreme paroxysmal changes in breath, circulation, and urine volume within 24 hours after induced labor, which should be monitored dynamically for effective and timely adjustment of respiratory circulation support. This may be another key point for the rescue of this type of patient. To seize the opportunities to perform escharectomy, cover the wound with xenogenic skin graft, and perform skin grafting in time for wound repair remain the top priority.

[Influence of different inner dressings in negative-pressure wound therapy on escharectomy wound of full-thickness burn rabbits].

Objective: To explore the influence of different inner dressings in negative-pressure wound therapy (NPWT) on escharectomy wound of full-thickness burn rabbits. Methods: Eighteen Japanese white rabbits were inflicted with full-thickness burn on unilateral back. They were divided into polymer dressing group (PD), biological dressing group (BD), and silver biological dressing group (SBD), according to the random number table, with 6 rabbits in each group. On 3 days post burn, the wounds were performed with escharectomy, and then wounds of rabbits in group PD were covered with polyurethane foam. Wounds of rabbits in group BD were covered with porcine acellular dermal matrix (ADM) and wounds of rabbits in group SBD were covered with silver porcine ADM. Then continuous NPWT was performed on rabbits of the three groups for 7 days. Immediately after surgery and on post surgery day (PSD) 7, general observation of wound was conducted and tissue around the wound was harvested for determination of dry to wet weight ratio. The content of bacteria was counted and the content of tumor necrosis factor α (TNF-α), interleukin-1ß (IL-1ß), and IL-6 in wound was determined by enzyme-linked immunosorbent assay. Fibroblasts in wound were counted after Masson staining and number of microvessels was counted after CD31 antibody immunohistochemical staining. Data were processed with analysis of variance for repeated measurement, LSD-t test, paired samples t test, and Bonferroni correction. Results: (1) Immediately after surgery, there was no granulation tissue in basal wound of rabbits in the three groups, with rich blood supply and obvious edema. On PSD 7, much granulation tissue was found in basal wound of rabbits in the three groups, with no or mild edema and no obvious redness and swelling in wound edge. (2) There were no significant differences in dry to wet weight ratios of tissue around the wound among and within the three groups immediately after surgery and on PSD 7 (with F values respectively 0.70 and 0.09, t values from 0.17 to 0.52, P values above 0.05). (3) Immediately after surgery, the content of bacteria in wounds of rabbits in groups PD, BD, and SBD was respectively (603.0±146.0) ×10(4,) (573.0±63.0) ×10(4,) and (590.0±100.0)×10(4) colony-forming unit (CFU)/g, with no significant difference among them (F=0.13, P>0.05). On PSD 7, the content of bacteria in wounds of rabbits in groups PD, BD, and SBD were respectively (5.4±0.8) ×10(4,) (4.6±0.9) ×10(4,) and (3.5±0.9)×10(4) CFU/g. Among them, the content of bacteria in wounds of rabbits in group SBD was lower than that in groups PD and BD, respectively (with t values respectively 3.78 and 2.29, P<0.05 or P<0.01). The content of bacteria in wounds of rabbits in the three groups on PSD 7 was decreased compared with that immediately after surgery (with t values from 10.05 to 21.81, P values below 0.01). (4) There was no significant difference in content of TNF-α, IL-1ß, and IL-6 in wounds of rabbits in the three groups immediately after surgery and on PSD 7 (with F values from 0.10 to 1.89, P values above 0.05). The content of TNF-α in wounds of rabbits in the three groups on PSD 7 was significantly higher than that immediately after surgery (with t values from 2.93 to 5.01, P<0.05 or P<0.01). (5) There was no significant difference in amount of fibroblasts in wounds of rabbits in the three groups immediately after surgery and on PSD 7 (with F values respectively 0.01 and 0.81, P values above 0.05). The amount of fibroblasts in wounds of rabbits in the three groups on PSD 7 was larger than that immediately after surgery (with t values from 4.78 to 11.58, P values below 0.01). (6) There was no significant difference in number of microvessels in wounds of rabbits in the three groups immediately after surgery and on PSD 7 (with F values respectively 2.42 and 2.49, P values above 0.05). The number of microvessels in wounds of rabbits in the three groups on PSD 7 was larger than that immediately after surgery (with t values from 7.17 to 11.14, P values below 0.01). Conclusions: SBD is better at inhibiting the growth of bacteria. PD, BD, and SBD have almost the same effects on reducing tissue edema and inflammatory reaction, and on promoting the accumulation of collagen fibers and tissue vascularization.

[Effects of different fluid resuscitation program on renal function in swine during shock stage of severe burn].

Objective: To explore the effects of different fluid resuscitation program on renal function in swine during shock stage of severe burn. Methods: Twenty-four Guangxi Bama miniature swine were inflicted with 40% total body surface area on the back, and then they were divided into four groups according to the random number table, with 6 swine in each group. At post injury hour (PIH) 2, swine in succinylated gelatin group (S), hydroxyethyl starch group (H), and allogeneic plasma group (A) were respectively resuscitated with succinylated gelatin, hydroxyethyl starch 130/0.4, and plasma according to burn shock " domestic general" resuscitation formula, and swine in Parkland group (P) were resuscitated with lactated Ringer's solution according to Parkland formula. Hemodynamic indexes including heart rate, blood pressure, urine volume, pulmonary capillary wedge pressure, and central venous pressure before injury, at the first and second PIH 24 were recorded. The volume of resuscitation fluid was calculated at the first and second PIH 24. Blood and urine samples were collected before injury and at PIH 4, 8, 24, and 48, and then serum creatinine and urea nitrogen were detected by automatic biochemical analyzer, urine microalbumin and urine creatinine were detected by automated urine analyzer and the ratio of which was calculated. The renal tissue of swine in each group was obtained at PIH 48, and the pathologic changes were observed by optical microscopy and electron microscope. Data were processed with analysis of variance of repeated measurement, one-way analysis of variance, and LSD test. Results: (1) The hemodynamic indexes of swine in each group were similar before injury and at the first and second PIH 24 (with P values above 0.05). Compared with those before injury, except that the heart rate of swine in group A had no significant change at the first PIH 24 (P>0.05), the heart rate of swine in each group was significantly increased at the first and second PIH 24 (with P values below 0.01); except that the systolic blood pressure of swine in group P was significantly increased at the first and second PIH 24 (P<0.05 or P<0.01), there were no significant changes of systolic blood pressure and diastolic blood pressure of swine in each group at the first and second PIH 24 (with P values above 0.05); except that urine volume of swine in groups S and A was significantly decreased at the first PIH 24 (P<0.05 or P<0.01), there were no significant change of urine volume of swine in each group at the first and second PIH 24 (with P values above 0.05); pulmonary capillary wedge pressure and central venous pressure of swine in each group were significantly increased at the first and second PIH 24 (P<0.05 or P<0.01). (2) Compared with that in group A, the volume of resuscitation fluid of swine in groups S and H had no significant change in the first and second PIH 24 (with P values above 0.05), while it was significantly increased in group P in the first PIH 24 and significantly decreased in the second PIH 24 (with P values below 0.05). (3) Compared with those in group A, except that serum creatinine of swine in group H was significantly increased at PIH 24 and significantly increased in group P at PIH 4, 8, 24, and 48, urea nitrogen of swine in group P was significantly decreased at PIH 4 and 8 and significantly increased at PIH 48, the ratio of urine microalbumin to urine creatinine of swine in group P was significantly increased at PIH 8, 24, and 48 (P<0.05 or P<0.01), serum creatinine, urea nitrogen, and the ratio of urine microalbumin to urine creatinine of swine in each group had no significant change at each time point (with P values above 0.05). Serum creatinine of swine in group P was (125±16) µmol/L at PIH 24, which was significantly higher than that before injury [(75±13) µmol/L, P<0.05]. Urea nitrogen of swine in group S was (2.90±1.17) µmol/L at PIH 48, which was significantly lower than that before injury [(4.60±0.47) µmol/L, P<0.05]; urea nitrogen of swine in group H was (4.82±0.82) µmol/L at PIH 4, which was significantly higher than that before injury [(3.80±0.73) µmol/L, P<0.05]; urea nitrogen values of swine in group A were respectively (4.80±0.33), (4.92±0.35), and (2.60±0.27) µmol/L at PIH 4, 8, and 48, while those at PIH 4, 8 were significantly higher and at PIH 48 was significantly lower than the value before injury [(3.93±0.32) µmol/L, with P values below 0.01]. The ratios of urine microalbumin to urine creatinine of swine in group P were respectively (106.7±16.4) and (171.6±36.9) mg/mmol at PIH 24 and 48, which were significantly higher than the ratio before injury [(59.0±3.0) mg/mmol, with P values below 0.01]. The serum creatinine, urea nitrogen, and the ratio of urine microalbumin to urine creatinine of swine in each group at the other time points were similar to those before injury (with P values above 0.05). (4) The renal tissue of swine in the four groups had no obvious pathological change. Conclusions: According to the renal function results, fluid resuscitation with electrolyte and colloids are better than with lactated Ringer's solution in swine during shock stage of burn injury, while natural colloids and succinylated gelatin have similar effects, and both are superior to hydroxyethyl starch 130/0.4.