The Clinical Study Of Main Influencing Factors Of Ventilator Weaning From Patients With The Long Term Mechanical Ventilation

With the development of respiratory support and universalapplying of mechanical ventilation technique, the significance ofmechanical ventilation is paid more and more attention to long-term lifesupport and respiratory treatment after operation. But mechanicalventilation itself is also a double-blade swords, it is difficult orimpossible for long-term ventilation patient to wean from ventilator. Sowe have taken a retrospective analysis in the patients who have receivedmechanical ventilation for more than seven days. Now the results arereported as follows.Objective: To analyze the main factors of ventilator weaning ofthe patients who have received long-term mechanical ventilation(≥7d)in ICU and to investigate the strategy of ventilator weaning inlong-term mechanical ventilation patients.Methods: The study group consisted of 45 long-term mechanicalventilation patients between October, 2002 and March,2005.The generalcondition, early trachea incision, primary diseases, the vital signs beforeventilation, accessory examination and acute physiology and chronichealth evaluation II(APECHâ…¡) were collected. There were other datasthat were also needed such as clinical analysis of blood gas beforeventilator weaning,ventilation parameters,respiratory and circulationindex,rapid-shallow-breathing index,P_(A-a)O₂,incidence andcomplications of ventilation-associated pneumonia during thehospitalization. All the patients were divided into two groups accordingto that whether the ventilator weaning succeed or fail. Comparativeanalysis was done with two groups of enacting clinical data. Results: There are 23 patients becoming the successful weaningpatients; And 22 patients becoming the failure weaning patients. Thesuccessful group's indexes of weaning in patients with mechanicalventilation are lower than the failure group. And the APECHâ…¡scoresof the failure group are much higher than the successful group, it has themarked differentia (P<0.01). The ratio of tracheotomy in successfulgroup is significantly higher than the failure group (P<0.05). The RSBI,P(A-a)O2 in failure group is obviously higher than the successfulgroup(P<0.01).The albumin and ventricular function of successfulgroup is much better than the failure group. Discussion: The terminal aim of the mechanical ventilation is towean from ventilator. Whether to wean from ventilator successfully isthe important essence to determine the prognosis of the mechanicalventilation. So how to make ventilator weaning standard to fit thephysical function of the patients, so as to make the possibility ofventilator weaning into reality, is always the key of basic and clinicstudy of mechanical ventilation. 1,The influence of the general condition of mechanicalventilation to that whether ventilator weaning success or fail. We have taken a retrospective analysis in the patient whoreceived long term mechanical ventilation and found that most of themwere old people whose basic diseases mostly are COPD, cerebralischemic stroke, cerebral hemorrhagic stroke, neuropathy and musclelesion et al. Severity of basic disease and general conditions are thecauses of long term mechanical ventilation and the very importantinfluencing factors of ventilator weaning. Such show that the treatmentof primary disease, evoked etiology and nutrition supporting should bestrengthened. What's more ,the result also demonstrate that theAPECHâ…¡score, which presents the severity of the disease and acutephysiology and chronic health of the patients, of failure group is muchhigher than the successful group. So APECHâ…¡could indicate theprognosis of mechanical ventilation. Another result could also be foundthat the severity of failure group was the main factor which caused thefailure of long term mechanical ventilation. So the positive treatmentof primary disease is one of the keys of ventilator weaning. 2,The influencing factors at the anterior time and the earlytime of mechanical ventilation between the two group. The study demonstrates that rate of early trachea incision,CVP,Cr,Alb and incidence of cardiac systolic function are allinfluencing factors. Of such factors above, Alb of the failure group ofventilator weaning is much lower than the success one, and lower is Alb,higher is the mortality. The result indicates that Alb might be a factorwhich can forecast the failure of ventilator weaning. Furthermore, earlytrachea incision makes for success of ventilator weaning when longterm mechanical ventilation is taken, and the reason may be that thepatient with trachea incision is easy to aspirate sputum so as to VAP iseasy to controlled. Based on all above, early trachea incision should becarried out when the ventilator can not be weaned and the patient cannot recover in the near future. This research result also shows that the possibility of cardiacdysfunction is higher in the failure group of ventilator weaning thanthat in the success group, which means cardiac dysfunction is a maineffect factor in ventilator weaning. The key therapeutic countermeasurefor cardiac dysfunction is based on the right evaluation ofHemodynamic state and choosing the appropriate low assist ventilationmode, and also consider the respiratory and circulation factor to choosethe best PEEP, this maybe the right way for increasing the ventilatorweaning of the patients companied cardiac dysfunction. 3,The effect of the examination result of clinical analysis ofblood gas before ventilator weaning and ventilation parameters forthe ventilator weaning This research result shows that there is no obvious difference of theexamination results of blood gas between two groups, this is related tothe adjust of the ventilation parameters during mechanical ventilation,which means that the effect of the clinical analysis of blood gas beforeventilator weaning is not very important to wean from ventilator in thesetwo groups. This research result shows that the ventilation condition ofventilator in the failure team is higher than that in the success group,which maybe related to worse of the respiratory function of the patientsin the failure group, this leads to the failure of ventilator weaning. 4,The direction to ventilator weaning by comparingsome forecast factors of ventilator weaning. Rapid-shallow-breathing index (RSBI) is a main factor to directventilator weaning or to forecast it by evaluate the reserve capability ofthe respiratory muscle, so we compare the RSBI, the average is107.02±4.56 in the failure group, the average is 86.07±3.22 in thesuccess group, all above accord with the nowadays generally recognizeddata, it shows that RSBI≤105 is a believable forecast factor forventilator weaning.5,the effect of the incidence of VAP before ventilator weaningto ventilator weaning This research result shows that the incidence of VAP in the failuregroup is obvious higher than that in the success team, which means VAPis the main effect factor to the long term ventilator weaning. If we cannot control VAP means it is very difficult to wean from ventilator. Whilethe prolonging of the standby time make the VAP worse. There are somereports that it will increase the mortality of the ICU if we prolong theventilation time of tracheal intubation, we can increase the success ratioin some patients companied with those who were difficult to wean fromventilator by NIPPV. The Sequential ventilation mode of invasivemechanical ventilation combined with NIPPV may become thesupplementary method in the patients companied with those who weredifficult to wean from ventilator In a word, it always exists some difficult to wean fromventilator for the patients who have taken the mechanical ventilation fora long time. And the success rate of weaning is relatively lower. Andthere are a lot of complex agents to influence the weaning. Among theseagents, patients'basal condition,outcome of the primary disease,earlytracheotomy,serious complication,ALB level and strategy of weaning,all of the above agents influence the achievement of weaning andprognosis. So we consider that evaluating the above agents beforetaking the mechanical ventilation can enhance the success rate ofweaning and improve the prognosis of the long-term mechanicalventilation and use the medical resources rationally. To enhance thesurvival rate, beside the mechanical ventilation, it also need to cure theprimary disease actively, prevent the VAP and MODS, reinforce thenutrition support, be treated logically, and help the patients to resumethe independent breath, wean the mechanical ventilation. Additionally, itis very important to enhance the weaning technique, strengthen theweaning consciousness, regulate the weaning strategy. But in clinical, itexists different viewpoints and arguments on how to grasp the weaningof the long-term mechanical ventilation patients. This still needlarge-scale and multi-center clinical researches to obtain the evidence ofevidence-based medicine. We believe that the weaning of the long-termmechanical ventilation patients will find a reasonable project with theprogress of the medical theory and the mature of the ventilationtechnology. The main causes of lower success rate of ventilator weaning inlong term mechanical ventilation attribute to that primary diseasesaggravated and severer complication take place. The basal conditionbefore taking on the mechanical ventilation, heart function andAPECHEâ…¡score are predictive to the success and failure of weaning.Blood gas indexes before weaning the long term mechanical ventilationis non-specific meaning to the weaning. RSBI, P(A-a)O2 is practical,concise and credible to make sure of the weaning time.