The Clinical Study Of Compliance, Oxygenation, Respiration, And Effort(CORE) Index As A Predietor For Weaning In ICU Patients With Mechanical Ventilation

Determine whether able to tolerance of weaning form mechanicalventilation is difficult in clinical in the intensive care unit （ICU）. Unsuccessfulweaning often results in respiratory-muscle fatigue and reintubation.Unsuccessful extubation is associated with higher mortality, prolongedmechanical ventilation, longer ICU and hospital stay, and transfer to along-term-care facility. The use of index to predict weaning outcome canavoid premature extubation and unnecessary prolongation of ventilationsupport. The traditional indicators included such as tidal volume, respiratoryrate, minute ventilation, vital capacity, and maximal inspiratory pressure.However, these parameters do not have high accuracy in predicting weaning.To improve accuracy, individual variables have been combined into integratedindex. The ratio of respiratory rate to tidal volume （f/V_T）, the rapid-shallowbreathing index（RSBI） is the most widely used weaning parameter and oftenused in protocols. However, some studies have indicated RSBI has lowaccuracy for predicting spontaneous breathing trial （SBT） outcome. In recentyears, more than one integrated weaning index, including the compliance, rate,oxygenation, and pressure（CROP） index, the compliance, oxygenation,respiration, and effort（CORE） index, and the Integrated Weaning Index（IWI）have been developed. The formula of CROP:CROP=[C_dyn×P_Imax×(P_aO2/P_AO2)]/fin which C_dynis dynamic compliance, P_Imaxis maximum inspiratorypressure, P_AO2is alveolar partial pressure of oxygen, and f is respiratory rate.The CROP index, as an individual predictors, has high specificity. Somestudies have found the airway occlusion pressure has a high specificity forsuccessful SBT. Delisle et al devised the CORE index based on CROP: CORE=[C_dyn×(P_Imax/P_0.1)×(P_aO2/P_AO2)]/fAnd they found the CORE index was the most powerful SBT predictor atpresent. But they did not comepare the prediction accuracy of weaning in thedifferent SBT modes.Objective: To observed the values of the CORE and RSBI index aspredictors for sueessful weaning in SBT with low levels pressure supportventilation （PSV） and T-piece.Methods: The study was conducted in April2012to December2012, and70patients with mechanical ventilation for more than72hours were choosed,When the underlying cause of respiratory failure had been improved orremoved, the patients reached weaning criteria and were involved intoweaning process. Based on SBT,70patients were divided into two groups,which were the PSV group and T-piece group. The duration of SBT was120min. Before SBT, we measured and recorded weaning indexes[Airwayocclusion pressure (P_0.1), Maximal inspiratory pressure (P_Imax), Lung dynamiccompliance (C_dyn), tidal volume （V_T）, breathing rate（f）], and calculated CROEindex and RSBI in each group. SPSS13.0statistical software was used forgenerally variable statistical analysis, and enumeration data in two groupswere compared using the t-test, and X2test were used for measurement data. Astatistical significant was P-value＜0.05. For variables, which had astatistically significant difference between the two groups, were evaluated bycalculating the area under the receiver operating characteristic curve （AUC）using MedCalc11.4. And use the receiver operating characteristic （ROC）curve to detect the sensitivity, specificity, specificity, negative predictive value,positive predictive value, negative likelihood ratio, and positive likelihoodratio of CORE index and RSBI.Result：1The average age in the low levels PSV group and in the T-piece groupwere70.46±9.748,65.63±12.365years old, respectively p=0.074. The averageof APACHEⅡ score were18.00±6.03,18.69±3.92, resp-ectively p=0.575.The average of duration of ventilation were146.77±86.91,129.91±52.16, respectively p=0.251. The age, the APACHEⅡscore, and the duration ofventilation had no significant difference between the two groups. In low levelsPSV group enroll3female and T-piece group enroll11female, p=0.017, thedifference was significant between the two groups.2Forty-two patients were successfully passed SBT and weaning fromventilator and28patients were failed. The successful weaning ratio was60%.in the low levels PSV group, the successful weaning ratio was54.29%, and inthe T-piece group was65.71%. There was no statistical difference between thetwo groups,p=0.329.3The average P_0.1in low levels PSV group and in T-piece group were3.011±0.90,3.65±0.87,respectively p=0.004.the average of P_Imaxwere25.37±4.33，28.74±3.61,respectively p=0.001.The P_0.1,P_Imaxhad significantdifference between two groups. The average of f were24.97±3.28,25.11±3.12,respectively p=0.852.The average of V_Twere375.31±86.93,404.05±90.48,respectively p=0.180.The average of P_aO2were91.95±29.37,89.31±24.32,respectively p=0.683. The average of PaCO₂were37.13±5.44,38.32±8.32,respectively p=0.480. The f,V_T, P_aO2,PaCO₂had no significant differencebetween the two groups.4In low levels PSV group, the area of ROC curve of CORE index was0.901（95%CI0.752-0.976）,and in RSBI was0.880（95%CI0.725-0.965）,and no significant difference were found between the two groups p=0.737.TheCORE index: threshold （6.07）, sensitivity （0.947）, specificity （0.812）, positivepredictive value （0.857）, negative predictive value （0.929）, positive likelihoodratio （5.05）, negative likelihood ratio （0.065）. The RSBI: threshold （6.07）,sensitivity （0.842）, specificity （0.812）, positive predictive value （0.842）,negative predictive value （0.812）, positive likelihood ratio（4.49）, negativelikelihood ratio （0.19）.5In T-piece group, the area of ROC curve of CORE was0.848（95%CI0.686-0.946）, and RSBI was0.882（95%CI0.656-0.930）, and no significantdifference were found between the two groups p=0.605. The CROE index:threshold（4.59）, sensitivity（0.913）, specificity（0.833）, positive predictive value（0.913）, negative predictive value（0.833）, positive likelihoodratio（5.48）,negative likelihood ratio（0.10）. The RSBI: threshold （70）,sensitivity （0.913）, specificity （0.667）, positive predictive value （0.840）,negative predictive value （0.800）, positive likelihood ratio （2.74）, negativelikelihood ratio（0.13）.6In all patients of the two groups, the area of ROC curve of CORE was0.867（95%CI0.765-0.936）,and RSBI was0.850（95%CI0.745-0.924）, andno significant difference were found between the two groups p=0.694.TheCORE index: threshold （4.59）, sensitivity （0.952）, specificity （0.750）, positivepredictive value （0.857）, negative predictive value （0.929）, positive likelihoodratio （3.81）, negative likelihood ratio （0.063）.The RSBI: threshold （70）,sensitivity （0.881）, specificity （0.750）, positive predictive value （0.842）,negative predictive value （0.812）, positive likelihood ratio （3.52）, negativelikelihood ratio （0.16）.Conclusion:1Weaning using low levels PSV or T-piece, the weaning success ratiohad no significant difference.2In low levels PSV group, both the CORE index and RSBI wereaccurately indicators as predietors for sueeessful weaning. There were nosignificant difference between the two modes in weaning process.3In T-piece group, both the CORE index and RSBI were accuratelyindicators as predietors for sueeessful weaning. There were no significantdifference between the two modes in weaning process.4The total of the two groups, both the CORE index and RSBI wereaccurately indicators as predietors for sueeessful weaning. There were nosignificant difference between the two modes in weaning process.