Effect Of Invasive Mechanical Ventilation In AECOPD Patients With Severe Respiratory Failure And The Influencing Factors

Objective：To determine the clinical effect of invasive mechanical ventilation （IMV） and identifythe prognosis risk factors in patients with acute exacerbations of chronic obstructivepulmonary disease（AECOPD） with severe respiratory failure so as to improve theclinical efficacy.Methods：64cases of AECOPD with severe respiratory failure receiving the treatment of invasivemechanical ventilation in RICU in the306thhospital of PLA from January2008to June2012were retrospectively studied. The general information, changes of arterial bloodgas parameters before and after invasive mechanical ventilation, as well as the changesof biochemical indices before and after treatment in groups were collected and analyzed.Important parameters such as age, sex, smoking index, arterial blood gas parametersbefore and after IMV pH （PH）, partial pressure of carbon dioxide （PaCO₂）, partialpressure of oxygen （PaO₂）, oxygen saturation （SaO₂） were collected; Tested indicatorsbefore and after treatment （i.e., mechanical ventilation, weaning or before death） weremeasured: white blood cell count（WBC）, neutrophil percentage（NEU%）, C-reactiveprotein（CRP）, albumin（ALB）, hemoglobin（HGB）, duration of ventilation, APACHE-IIscore before IMV, sputum culture results, complications such as ventilator associated pneumonia（VAP）, multiple organ dysfunction syndrome （MODS）, electrolytedisturbances, diarrhea, liver injury, renal injury, gastrointestinal bleeding, heart failure,acute myocardial infarction were recorded. According to whether sueeessfullyventilator-weaned, all the patients were classified into three groups: weaning successgroup,weaning failure group and death group. The parameters of mechanical ventilationwas analyzed by t test; all independent prognostic risk factors were evaluated bymultivariate logistic regression analysis; relationship between the predicted mortality ofAPACHE-II and actual mortality was analyzed by the Spearman correlation test, theapplication value of predicted mortality rate was evaluated by ROC curve.Results：1. The mean age of enrolled patients was75.69±7.98years, the minimum age is54years, the maximum age is91years. The total length of mechanical ventilation rangedfrom3to226days, the median duration of MV was13（7,25）days.2. Finally,35cases successfully ventilator-weaned, weaning success rate was54.7%;14cases of weaning failure,including8cases of reintubation mechanical ventilationagain（4cases of accidental extubation）,6patients with tracheotomy still requiredlong-term mechanical ventilation;15patients died, the mortality rate was23.4%.22patients ventilated for more than21days, which accounted for34.4%;6patientsreceived repeated mechanical ventilation therapy, one patients underwent mechanicalventilation for5times.3. Arterial blood gas analysis parameters （PH,PaCO₂,PaO₂,SaO₂） before and after thetreatment of IMV were improved significantly in the weaning success group, failuregroup and death group （P<0.05or P<0.01）. WBC and NEU%were significantlydecreased after treatment in success group and failure group（P <0.05）, except in the death group; but after treatment, WBC and NEU%were significantly higher in deathgroup than the other two groups （P<0.05）. HGB and ALB were significantly lower indeath group after treatment than that before treatment, and were significantly lower thanthe other two groups（P<0.05）; and on the contrary, in the weaning success group, ALBcontent increased. There was no significant change of CRP in each group before andafter treatment, but it was significantly higher in death group than the other twogroups（P<0.05）.4. Univariate analysis showed age, admission HGB, WBC,N%,CRP,HgB and ALB aftertreatment, MODS and ventilation time were the influencing factors of poor prognosisfor AECOPD with severe respiratory failure（P<0.05）. Multivariate logistic regressionanalysis showed that age （P=0.018, OR:0.746,95%CI:0.585-0.951）, admission HGB（P=0.008, OR:0.909,95%CI:0.846-0.976）, NEU%after treatment（P=0.014, OR:1.365,95%CI:1.066-1.747）, ALB after treatment （P=0.006, OR:0.531,95%CI:0.339-0.831）,duration of ventilation （P=0.009, OR:1.087,95%CI:1.021-1.158） were independentinfluencing factors of weaning failure; admission HGB （P=0.002, OR:0.878,95%CI:0.808-0.953）, NEU%after treatment （P=0.002, OR:1.620,95%CI:1.194-2.198）,ALB after treatment （P=0.003, OR:0.431,95%CI:0.247-0.753）, duration of ve-ntilation （P=0.009, OR:1.098,95%CI:1.023-1.178） and MODS（P=0.046, OR:44.879,95%CI:1.062-1895） were independent influencing factors of death.5. The mortality rate is higher with the increase of APACHE-II score, Spearmancorrelation analysis showed that the correlation coefficient rp=0.941（P=0.005）, thepredicted mortality of APACHE-II is higher than the actual mortality. The area under theROC curve of APACHE-II（Az） is0.642（P=0.050,95%CI:0.503-0.781）; when theAPACHE-II score reached28.5, the Youden index was the highest （0.398）, so oncethe APACHE-II score is above28points, the mortality rate increased significantly. Conclusion：Mechanical ventilation is a effective and reliable method to rescue and treat AECOPDpatients with severe respiratory failure，and can prolong their survival time. Effectivetherapeutic interventions on these independent prognostic risk factors is the key toimprove the clinical therapeutic effect. APACHE-II score can be used to evaluate theseverity of illness, but only has a limited value predicting the mortality for AECOPDpatients with severe respiratory failure.