| Postoperative cerebrospinal fluid leakage is a common clinical complication in spinalsurgery and neurosurgery, with an incidence up to10%. Postoperative cerebrospinal fluidleakage can delay wound healing, and even develop into fatal complications such asintracranial infection. Spinal surgeons and neurosurgeons have developed methods to preventpostoperative cerebrospinal fluid leakage, including improving suturing of spinal dura materand coverage and suture of various soft tissues. However, the therapeutic effects of thesemethods are not satisfying. As a result, various biomaterials have been developed for clinicalapplication, including DuraSeal, BioGlue, EVICEL, and Tisseel. However, these productshave various drawbacks and contraindications, and there’s no conclusion on which one isbetter. In this study, a novel biomaterial–temperature-responsive hydroxybutyl chitosan–was used in the prevention of postoperative cerebrospinal fluid leakage. This material canrapidly convert into gel (37°C) from the liquid state (2°C-4°C) and had excellent gel strength.We investigated the efficacy of temperature-responsive hydroxybutyl chitosan in theblockage of cerebrospinal fluid leakage in macaques.Part oneObjective To evaluate the mechanical properties of a novel biomaterial,temperature-responsive hydroxybutyl chitosan, in prevention of postoperative cerebrospinalfluid leakage.Methods1、Determination of gelation timeFive mL of temperature-responsive hydroxybutyl chitosan at each concentration was transferred into a flasket with a diameter of2cm and standardized at4°C. The flaskets werethen placed into a water bath at a constant temperature of37°C. The flasket was inclinedevery5seconds until the fluid stop flowing. Gelation time was defined as the time taken fromleaving the environment of4°C to the gel status.2、Destructive testingTemperature-responsive hydroxylbutyl chitosan at each concentration was divided intosamples with a thickness of5mm, and destructive testing in a water bath at37°C wasperformed using the Ramp program of an electron universal tester. Force value detected bythe probe with a mobile velocity of0.1mm/s was recorded when each gelation sample wasdestroyed at each concentration.3、Fatigue test of temperature-responsive hydroxybutyl chitosanTemperature-responsive hydroxylbutyl chitosan at each concentration was divided intosamples with a thickness of5mm, and a fatigue test in a water bath at37°C was performedusing the electron universal tester with a maximum mobile probe depth of1.7mm and afrequency of1.3Hz for600impulses. The force value of the probe in the1st,200th,400th, and600thpulse achieving the maximum depth was recorded using the Sine program, and the fourforce values were analyzed byStudent’s t-tests.4、Frequency sweep of temperature-responsive hydroxybutyl chitosanTemperature-responsive hydroxylbutyl chitosan of2mL at each concentration wasplaced on the sample stage of a rheometer at37°C in a changing range of4%and frequencyrange from0.1–10Hz. The frequency sweep was performed to record G’ value at different frequencies, and the coefficient of variation was calculated.ResultsMeasurements of gelation time of temperature-responsive hydroxybutyl chitosanMeasurements of gelation time of temperature-responsive hydroxybutyl chitosan in thethree groups are shown in Table1. Gelation time of temperature-responsive hydroxybutylchitosan was reduced with an increase in concentration (p<0.05); the results showed thatgelation time of the material at1.5%might be more adaptive for practical application.Destructive testing of temperature-responsive hydroxybutyl chitosanThe force value of each sample during destructive testing is shown in Figure1, Figure2, andTable2. The95%confidence interval of mean pressure endured by temperature-responsivehydroxybutyl chitosan at different concentrations were as follows: concentration of1.5%:50.3–60.1kPa; concentration of2%:70.6–122.5kPa; and concentration of3%:77.8–104.7kPa,all of which were significantly higher than normal human cerebrospinal fluid pressure of0.29–1.76kPa (p <0.05).Fatigue test of temperature-responsive hydroxybutyl chitosanFatigue tests of the samples in three groups are shown in Table3. There was nostatistical significance in the mean value of each sampling at1.5%. The statistical analysis offatigue test of temperature-responsive hydroxybutyl chitosan at1.5%is shown in table4. Thedata show that there is no evident deformation in the sample at1.5%, with excellentanti-fatigue properties occurring during the test. However, there was a significant differencein the force value of the probe at the maximum depth during different test stages in the2%and3%concentrations (P<0.05), which indicated that these two samples generateddeformation or rupture during the test with worse anti-fatigue properties than the1.5% sample.Frequency sweep of temperature-responsive hydroxybutyl chitosanThe frequency sweep of temperature-responsive hydroxybutyl chitosan at eachconcentration revealed that CV (coefficient of variation) at each concentration was less than5%. It also showed that the compound at37°C with a CV of4%and frequency of0.1–10Hzhad excellent stable strength (Table.4).Conclusion hydroxybutyl chitosan at1.5%concentration passed all the test showing a goodstrength then the other two. Part twoObjective To evaluate the efficacy of a novel biomaterial, temperature-responsivehydroxybutyl chitosan, in prevention of postoperative cerebrospinal fluid leakage.Methods Ten laboratory macaques were randomized into2groups of5animals each, withGroup A as the experimental group and Group B as the control group. The two groups all hadreceived resection of the T11, T12, L3, and L4vertebral plates with resulting exposure of spinaldura mater. Subsequently, the epidural catheter was inserted into the T11and T12caudal ward.A longitudinal cleft of spinal dural mater in L3and L4at a length of0.5cm was made. Whenbright cerebrospinal fluid leakage occurred, the incision and wound surface were covered bytemperature-responsive hydroxybutyl chitosan in Group A, while none of materials were usedfor the blockage in Group B. Methylene blue was infused into the T11and T12catheter, andcerebrospinal fluid leakage in the incision of L3and L4dura mater in the two groups of macaques were observed. The effective rates of the two groups were tested by F isher’s testswith a significance level of P<0.05.One macaque was randomized from each of the two groups, and acetrizoic acid of2mLwas infused into the T11and T12catheter after closing the incision. Lumbar vertebrae positionwas photographed to observe leakage of contrast medium.Results Modeling of L3and L4cerebrospinal fluid leakage in10macaques was successfullyestablished. Five macaques in Group A showed excellent blockage after injection of0.5mLmethylene blue using temperature-responsive hydroxybutyl chitosan for the coverage. The5macaques in the control group had no effects of blockage with severe out-flow of methyleneblue. Statistical analysis indicated significant differences in the effective rates of the twogroups using Fisher’s exact probability (P<0.05). The temperature-responsive hydroxybutylchitosan had favorable effect in the prevention of cerebrospinal fluid leakage.1mL of acetrizoic acid at a concentration of76%was slowly infused into the catheterunder the dura mater in one macaque randomized from the two groups, and the lumbarvertebrae were photographed. The spinous process and vertebral plate at the incision of theL3and L4spinal dura mater had been removed in experimental group, the visualization ofdura mater boundaries in corresponding segments was clear, and no high-density shadowswere observed out of the dura mater. This showed that there was no leakage of contrast agentfrom the incision of L3and L4spinal dura mater. However, leakage of contrast agent wasobserved in the corresponding segment of lumbar vertebrae in the control group.Conclusion hydroxybutyl chitosan at1.5%concentration nicely performed in the test ofpreventing the postoperative cerebrospinal fluid leakage... |
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