ObjectiveTo evaluate the predictive value of mini-fluid challenge for volume responsiveness in patients under shock.MethodsSixty patients diagnosed as shock were included in the study. A 50 mL infusion of physiological saline over 10 seconds and a further 450 mL over 15 minutes were conducted through the central venous catheter. Cardiac output (CO), global end-diastolic volume index (GEDVI), central venous pressure (CVP) and extravascular pulmonary water index (EVLWI) were monitored by the pulse indicator continuous cardiac output monitoring. If the increase of CO after 500 mL volume expansion (ΔCO500) ≥10%, the patient was considered to be with volume responsiveness. The relevance between ΔCO50 and ΔCO500 was analyzed, and the sensitivity and specificity of the ΔCO50 were analyzed by receiver operating characteristic (ROC) curve.ResultsAfter 50 mL volume injection, the heart rate and systolic blood pressure of the two groups did not change obviously. The CVP of non-responders changed slightly higher than that of responders, but neither of them had obviously difference (P>0.05). The CO of responders had increased significantly (P<0.05) which was in accord with that after a further 450 mL volume injection. GEDVI and EVLWI did not change significantly (P>0.05). ΔCO50 and ΔCO500 were strongly correlated (r=0.706, 95%CI 0.677 - 0.891, P>0.05). The area under ROC curve for ΔCO50 was 0.814 (95%CI 0.707 - 0.922).ConclusionThe volume responsiveness of patients under shock can be predicted by mini-fluid challenge study which is related to normal volume expansion and it does not increase the risk of pulmonary edema.
To investigate the γ pass rate limit of plan verification equipment for volumetric modulated arc therapy (VMAT) plan verification and its sensitivity on the opening and closing errors of multi-leaf collimator (MLC), 50 cases of nasopharyngeal carcinoma VMAT plan with clockwise and counterclockwise full arcs were randomly selected. Eight kinds of MLC opening and closing errors were introduced in 10 cases of them, and 80 plans with errors were generated. Firstly, the plan verification was conducted in the form of field-by-field measurement and true composite measurement. The γ analysis with the criteria of 3% dose difference, distance to agreement of 2 mm, 10% dose threshold, and absolute dose global normalized conditions were performed for these fields. Then gradient analysis was used to investigate the sensitivity of field-by-field measurement and true composite measurement on MLC opening and closing errors, and the receiver operating characteristic curve (ROC) was used to investigate the optimal threshold of γ pass rate for identifying errors. Tolerance limits and action limits for γ pass rates were calculated using statistical process control (SPC) method for another 40 cases. The error identification ability using the tolerance limit calculated by SPC method and the universal tolerance limit (95%) were compared with using the optimal threshold of ROC. The results show that for the true composite measurement, the clockwise arc and the counterclockwise arc, the descent gradients of the γ passing rate with per millimeter MLC opening error are 10.61%, 7.62% and 6.66%, respectively, and the descent gradients with per millimeter MLC closing error are 9.75%, 7.36% and 6.37%, respectively. The optimal thresholds obtained by the ROC method are 99.35%, 97.95% and 98.25%, respectively, and the tolerance limits obtained by the SPC method are 98.98%, 97.74% and 98.62%, respectively. The tolerance limit calculated by SPC method is close to the optimal threshold of ROC, both of which could identify all errors of ±2 mm, while the universal tolerance limit can only partially identify them, indicating that the universal tolerance limit is not sensitive on some large errors. Therefore, considering the factors such as ease of use and accuracy, it is suggested to use the true composite measurement in clinical practice, and to formulate tolerance limits and action limits suitable for the actual process of the institution based on the SPC method. In conclusion, it is expected that the results of this study can provide some references for institutions to optimize the radiotherapy plan verification process, set appropriate pass rate limit, and promote the standardization of plan verification.
Simulation of the human biological lung is a crucial method for medical professionals to learn and practice the use of new pulmonary interventional diagnostic and therapeutic devices. The study on ventilation effects of the simulation under positive pressure ventilation mode provide valuable guidance for clinical ventilation treatment. This study focused on establishing an electrical simulation ventilation model, which aims to address the complexities in parameter configuration and slow display of air pressure and airflow waveforms in simulating the human biological lung under positive pressure ventilation mode. A simulated ventilation experiment was conducted under pressure-regulated volume control (PRVC) positive pressure ventilation mode, and the resulting ventilation waveform was compared with that of normal adults. The experimental findings indicated that the average error of the main reference index moisture value was 9.8% under PRVC positive pressure ventilation mode, effectively simulating the ventilatory effect observed in normal adults. So the established electrical simulation ventilation model is feasible, and provides a foundation for further research on the simulation of human biological lung positive pressure ventilation experimental platform.
Objective To evaluate the influence of tidal volume on the accuracy of stroke volume variation ( SVV) to predict volume state of pigs with ventilation.Methods Thirty-six healthy pigs were anesthetized after tracheal intubation and ventilated. With the envelope method, they were randomized into a normovolemia group, a hemaerrhagic shock group, and a hypervolemia group, with 12 pigs in each group. The pigs in the hemaerrhagic shock group were removed 20 percent of blood, and the pigs in the hypervolemia group received additional infusion of 20 percent 6% hydroxyethyl starch. In each group, ventilator settings were changed in a randomized order by changing VT [ VT = 5 mL/kg ( VT5 ) , VT =10 mL/kg ( VT10 ) , and VT =15 mL/kg ( VT15 ) ] . Hemodynamic measurements [ heart rate ( HR) , mean arterial boold pressure ( MAP) , systemic vascular resistance index ( SVRI) , cardiac index ( CI) , stroke volume index ( SVI) , intrathoracic blood volume index( ITBVI) , and SVV] were obtained after 10 minutes of stabilization. Results SVV was increased in the hemaerrhagic shock group comparing with the normovolemia group for VT10 [ ( 21 ±5) % vs. ( 11 ±2) % , P lt;0. 05] , but SVV was decreased in the hypervolemia group comparing with the normovolemia group [ ( 7 ±2) % vs. ( 11 ±2) % , P lt; 0. 05] . The variation tendency for VT15 was the same with VT10 , moreover SVV were all above 12% for the hemaerrhagic shock group, the normovolemia group, and the hypervolemia group [ ( 30 ±7) % , ( 19 ±3) % , and ( 15 ±4) % ] . There were no significant diffrences among the hemaerrhagic shock group, hypervolemia group and normovolemia group [ ( 8 ±6) % ,( 7 ±5) % , and ( 7 ±4) % , P gt; 0. 05] for VT5 . Conclusions SVV was a precise indicator of cardiac preload, but SVV was less sensitive to the changes of volume during low tidal volume ( 5 mL/kg) ventilation. The threshold of SVV for predicting fluid responsiveness maybe above 12% with a high tidal volume ( 15 mL/kg) ventilation.
ObjectiveTo investigate the role of amygdala volume index(AVI) in surgcial evaluation in patients with mesial temporal lobe epilepsy (mTLE), including clinical features, etiologies and surgical outcome. MethodsThirty six patients were diagnosed as mTLE after surgical evaluation including clinical manifestations, video-electroencephalogram (VEEG) and magnetic resonance imaging (MRI) at the Second Affiliated Hospital of Zhejiang University between March 2013 and March 2016. Bilateral amygdala AVI was then calculated from amygdala volumes on MRI, which were measured with region of interest (ROI) analysis. All patients were treated surgically. Etiologies of mTLE were further confirmed by the histopathology of the resected tissue. ResultsAmong the 35 patients, there is a strong correlation between AVI on the lesion side and age of onset (R =-0.389, P = 0.019) as well as age of surgery (R =-0.357, P = 0.032). No obvious relation can be seen between AVI and gender, history of febrile convulsion, duration of epilepsy, secondary generalized seizure, side of lesion, presurgical seizure frequency and electrode implantation. There is no significant difference in AVI among the five etiologies. At follow-up, thirty patients (80.5%) reached seizure-free, AVI on the lesion side is nota predictor of surgical failure (P > 0.05). ConclusionAVI plays a role in etiology evaluation in patients with mesial temporal lobe epilepsy. Moreover, a larger AVI on the lesion side is correlated with an earlier age of onset. There is limited value of amygdala volume insurgical outcome prediction of patients with mTLE.
ObjectiveTo study the model to predict thymus volume with two-dimensional section diameters among fetuses. MethodsFrom September 2010 to March 2012, 210 singleton pregnant women suspected with fetal abnormality by prenatal ultrasonic testing were confirmed using MRI technology. Three two-dimensional section diameters of thymus were measured and the volume was calculated. No abnormal fetuses regarded as the standard, theoretical normal volume of fetal thymus was calculated. Paired t-test was used to compare the actual thymus volume with its corresponding theoretical normal value, and thus the fetuses were divided into two groups of normal and dysplasia so as to establish predictive model respectively. With two-dimensional section diameters as independent variables and thymus volume as dependent variable, the linear regression model was established. According to the model, the thymus volume was predicted and the error rate was calculated by formula: error rate=(predicted value-actual value) /actual value×100%. The Pearson correlation coefficient of error rate and fetal gestational age was calculated. ResultsThe models of normal and dysplasia groups to predict thymus volume were lnV=0.016d1+0.030d2+0.086d3+5.707+ε (R2=0.510) and lnV=0.048d1+0.036d2+0.016d3+6.011+ε (R2=0.447). The average absolute values of predicted error rate were 4.34% and 5.34% and decreased with fetal gestational age (normal r=-0.264, P=0.007; dysplasia r=-0.182, P=0.060). ConclusionThe prediction effects of above models are not so good and the model accuracy increases with fetal gestational age. Normal fetuses' model of different gestational age should be established to predict thymus volume by conducting large sample size study in the future. The modeling approach has certain practicability and clinical value and can be applied in ultrasonic technique.
Objective To compare the differences of flow and volume responses in patients with mild to very severe chronic obstructive pulmonary disease（COPD） in bronchodilatation test. Methods The different changes of FEV1 and FVC in 217 patients with mild to very severe COPD（GOLD stage Ⅱ-Ⅳ） after inhaling salbutamol were analyzed retrospectively. Results FEV1 and FVC of the patients with COPD at stage Ⅱ-Ⅳ increased remarkably after inhaling β2 agonist，while there were significant differences between the changes of FEV1 and FVC. Increment of FEV1 and FVC (ΔFEV1 and ΔFVC)，representing flow and volume responses respectively，showed a normal distribution. The majority of patients fell in the range of ΔFEV1 from 0.00 to 0.04，0.05 to 0.09 and 0.10 to 0.14 liter，and ΔFVC from 0.00 to 0.09，0.10 to 0.19 and 0.20 to 0.29 liter. There was significant difference of ΔFEV1 among stage Ⅱ-Ⅳ patients with COPD （Plt;0.01），namely more severe the disease less ΔFEV1 got.In the other hand ΔFVC increased along with the progression of COPD，although no significant difference of ΔFVC among stage Ⅱ-Ⅳ patients with COPD was found. Though different changes of ΔFEV1 and ΔFVC were revealed，there was a positive correlation between ΔFEV1 and ΔFVC in patients at each GOLD stage and the correlation became more insignificant with the progression of COPD. Conclusions There are significant differences between post-bronchodilator flow and volume responses in patients with COPD.Flow response decreases remarkably along with the progression of COPD，whereas volume response increases along with the progression of COPD.
Objective To investigate the therapeutic effects of biphasic positive airway pressure (Bilevel) ventilation and volume ventilation plus [VV+，including volume control plus (VC+) and volume support (VS)] on respiratory failure in patients with chronic obstructive pulmonary disease (COPD).Methods 63 patients with COPD complicated by acute respiratory failure were intubated and underwent mechanical ventilation for at least 24 hours.At the first patients were underwent assist-control (A/C) ventilation for 2 to 4 hours to obtain the suitable basic ventilatory parameters.Meanwhile，the hemodynamics and oxygen dynamic parameters were measured.Then the patients were randomly allocated to three groups with 21 patients in each group and the ventilation mode was switched to Bilevel，VC+ and A/C mode correspondingly.The setting parameter was identical in three modes.In the process of weaning，patients in Bilevel group were ventilated with Bilevel and pressure support ventilation (PSV) mode at each pressure level，and subdivided into Bilevel and PSV 1 group accordingly.In VC+ group，the mode was switched to VS and PSV mode and subdivided into VC+ group and PSV 2 group,respectively.Every mode was run for 30 minutes while the ventilation function，blood gas exchange and lung mechanics index were measured.Results In the initial stage，the airway peak pressure (PIP) of Bilevel and VC+ mode obviously decreased，and the respiratory compliance was higher compared to the A/C mode. The effectiveness of Bilevel and A/C was equivalent in improving alveolar ventilation and oxygenation.The difference in the change of circulation function and blood gas between the two groups were not significant (Pgt;0.05).In the process of weaning，the effectiveness of Bilevel and VV+ was equal to PSV.The changes of breathing mode and blood gas between the two groups had no significant differences.Conclusions Bilevel and VV+ mode ventilation can be used in the whole mechanical ventilation for acute respiratory failure due to COPD with lower PIP，higher respiratory compliance compared to A/C model and similar performance as PSV during mechanical ventilation withdrawn.
ObjectiveTo discuss the application value of the two kinds of three dimensional reformatting techniques of spiral CT: volume rendering (VR) and maximum intensity projection (MIP) in the evaluation of children's skeletal abnormality. MethodsEighteen children with skeletal abnormality in our hospital treated between March and June 2014 were recruited in this study, diagnosed by CT transversal images and images of multiplanar reformatting (MPR). VR and MIP were made with the raw data. All three dimensional images were independently evaluated by two doctors of the Radiology Department (a score of 1-4). Images with a score of 4 were excellent. Wilcoxon signed ranks test was done for all scores and Kappa values were calculated. ResultsImages score of VR was 3.28±0.96 and of MIP was 2.89±0.90, without statistically significant difference (Z=-1.732, P=0.125). Kappa value of VR was 0.730 and of MIP was 0.593, with good and moderate consistency. ConclusionWith the special superiority of displaying spatial configuration, VR and MIP can be used to help two dimensional CT images to evaluate children's skeletal abnormality more comprehensively.
ObjectiveCompare the two-degrade collimator (MLC) angle selection's impact on plan quality and operational efficiency for volumetric intensity-modulated radiotherapy (VMAT) in the treatment planning system, and to explore the scheme for treatment plan optimization. MethodsTwenty patients with nasopharyngeal carcinoma underwent the treatment between March and December 2013 were randomly selected and planned for SIBVMAT treatment with different parameters set in the range of 0-60°with 15°interval for collimator angles. Planned dose distribution to the target volumes, organs at risk, and monitor units were compared. ResultsAs the MLC angle increased, target conformal index and homogeneity index had a trend to became deteriorated. The optimal plans were 0°and 15°, while 45°and 60°plans gave poor protection for the organ at risk compare to other angle plans and the monitor units were significantly increased. ConclusionChange the MLC angle had visible impact on treatment plans,there was a trend to deteriorate with the MLC angle increased, but small changes in MLC angle range can theoretically reduce the influence from leakage radiation on the human body.