Research On Mechanical Ventilation In Patients With Acute Exacerbation Of Chronic Obstructive Pulmonary Disease

OBJECTIVE Non-invasive ventilation(NIV)was used in acute exacerbation of chronic obstructive pulmonary disease(AECOPD).NIV failure risks include baseline ABG and inability to correct gas exchange,increased severity of disease,increased respiratory rate.An elevated Procalcitonin(PCT)level was independently associated with an increased risk of invasive mechanical ventilation.However,it has been not clear whether high level of PCT was correlated with NIV failure and predicted need of endotracheal intubation.In this study,PCT levels were compared in AECOPD subjects between NIV failure and NIV success.The correlation between PCT levels and arterial blood gas(ABG)analysis,erythrocyte sedimentation rate,C-reactive protein(CRP),white blood cells,and neutrophils were also analyzed.METHODS This controlled case study was performed between May 2014 and March 2015.Hemogram,erythrocyte sedimentation rate,ABG,serum CRP,and PCT tests were performed before NIV were used.A quantitative assessment of PCT levels was performed,and the results were evaluated on the same day.RESULTS In the original investigation,402 exacerbations were screened and 376 subjects were enrolled.Two hundred and eighty six of them were treated successfully with NIV,and 90 received endotracheal intubation and mechanical ventilation due to NIV failure.Baseline clinical characteristics were compared between groups.PaCO2,serum PCT and CRP levels were higher,and pH level was lower in NIV failure group than in NIV success group.No significant correlation was found between PCT level and variable of arterial blood gas and inflammation markers,and only a weak positive correlation was found between PCT level and CRP level(r = 0.176,P = 0.019).To determine factors associated with NIV failure,binary logistic regression analysis was carried out using the following independent variables:age,sex,PCT level,CRP level,pH and PaCO2 level at admission,only PCT level,CRP level and PaCO2 level were significantly associated with NIV failure.We performed a ROC analysis to determine the predictive level of serum PCT,CRP and PaCO2 for assessing the need of IMV therapy.The cutoff values to achieve the highest Youden index were 0.31 ng/mL for PCT level(sensitivity,83.3%;specificity,83.7%),15.0 mg/mL for CRP level(sensitivity,75.6%;specificity,93.0%),and 73.5mmHg for PaCO2(sensitivity,71.1%;specificity,100%).The area under the curve(AUC)for each factor was 0.854(95%confidence interval[CI],0.793-0.914)for PCT,0.849(0.787-0.911)for CRP,and 0.828(0.761-0.896)for PaCO2,respectively.The AUC for the combination of PCT level,CRP level and PaCO2 increased to 0.978(0.961-0.995).CONCLUSIONS NIV failure group presented a higher serum PCT,PaCO2 and CRP levels,and lower pH level.Serum PCT level,CRP level and PaCO2 level were independently associated with NIV failure.High serum PCT level(?0.31 ng/mL),CRP level(?15.0 mg/mL),and PaCO2 level(?73.5mmHg)predict NIV failure for AECOPD subjects,and the combination of these three parameters might enable accurate prediction.OBJECTIVE An acute exacerbation of COPD(AECOPD)can lead to life-threatening hypercapnic encephalopathy(HE)that requires emergency intervention with mechanical ventilation.Invasive mechanical ventilation(IMV)is currently recommended as the gold-standard technique for the treatment of patients with AECOPD and HE.There is now good evidence from numerous studies that noninvasive ventilation(NIV)is an effective intervention in patients with HE.However,patients with HE and a depressed cough reflex are unable to efficiently clear copious secretions from their airways,and this can cause failure of NIV.An oropharyngeal airway(OPA)helps to establish a patent airway by preventing the tongue from covering the epiglottis.An OPA is used frequently in emergency care for short-term airway management in unconscious subjects with spontaneous respiration,and to facilitate manual ventilation with a facemask.We hypothesized that a combination of noninvasive techniques,including repeated suctioning of secretions from an OPA,appropriate patient posture,nebulized inhalation of salbutamol and ambroxol and close monitoring,could be used within an intensive care unit(ICU)to maintain a clear airway during the first two hours of NIV.The aim of this pilot study was to examine the safety and effectiveness of this treatment strategy in the clearing of airways during NPPV.An additional aim was to determine the outcomes of this strategy when administered(within an ICU)to patients with AECOPD and HE that would not typically be considered appropriate candidates for NIV because of their inability to remove copious secretions.METHODS This prospective cohort study was performed between October 2014 and October 2016 in Respiratory ICU(RICU).All included participants with HE in the RICU were randomly divided into two groups,NIV and IMV.Participants were managed using NIV,with airway management and clearance of secretions performed in the initial 2 hours of NPPV.including repeated suctioning of secretions from an OPA,appropriate patient posture,nebulized inhalation of salbutamol and ambroxol and close monitoring,could be used to maintain a clear airway during the first two hours of NIV.Participants who received IMV were carried out after admission to the RICU without NIV being first attempted.In addition to KMS score and ABG analysis,the primary endpoints were:(a)the safety(need for urgent ETI)and effectiveness(changes in ABGs and KMS)of the secretion clearing strategy within the first 2 hours of NPPV;and(b)the rate of major complications,especially septic complications and nosocomial pneumonia(including pulmonary aspiration)that were diagnosed using strict criteria.The secondary endpoints were:in-hospital mortality,1-year mortality,tracheostomy,duration of mechanical ventilation and length of hospital stay.RESULTS Of 186 patients with AECOPD screened for inclusion in the study,164 were included in the analysis(90 in the IMV group and 74 in the NPPV group).There were no significant differences between the two groups in any of the baseline characteristics.Compared to baseline,the ABGs improved significantly in both groups after 2 hours of mechanical ventilation,but no significant differences were observed in pH,PaO2/FIO2 and PaCO2 between the NIV and IMV groups within the initial 2-hour period(P = 0.124,0.095 and 0.740,respectively).The sensorium level significantly improved within 2 hours in the NIV group(P<0.001),but was not evaluated in the IMV group due to the use of sedation.Subjects receiving IMV had a higher complication rate than those receiving NIV due to a greater occurrence of nosocomial infections and use of more invasive devices.There were no differences between the two groups in the overall duration of mechanical ventilation and the length of hospital stay.However,Kaplan-Meier analysis showed that the percentage of subjects not weaned from mechanical ventilation within 30 days was significantly lower in the NIV group than in the IMV group(log rank 9.635,P = 0.002).CONCLUSIONS The use of an OPA and suction aspiration,in combination with appropriate positioning of the patient and nebulized inhalation of salbutamol/ambroxol,was a feasible,simple,safe and effective method for clearing respiratory secretions during the first 2 hours of NIV in patients in ICU with AECOPD and HE.Moreover,compared with IMV,this innovative strategy reduced the risks of nosocomial infection,requirement for intubation and hospital mortality,and showed superior results in terms of weaning from ventilation.Therefore,we propose that this novel NPPV strategy might be a successful alternative to IMV in selected patients with AECOPD in the ICU,where there is prompt access to ETI if needed.OBJECTIVE End-tidal carbon dioxide partial pressure gradients(PETCO2)refers to the measurement and display of carbon dioxide(CO2)concentrations in respiratory gases.There is broad appreciation of its value for assuring that endotracheal tubes are placed properly in the tracheal;it is also being used to guide tidal volume and rate settings during mechanical ventilation,focusing on the end-tidal value.Yet the full capnogram is much richer in information than generally appreciated,finding application to gauge the degree of ventilation(V)-perfusion(Q)mismatch;measure dead space and quantify airflow obstruction in asthma and chronic obstructive pulmonary disease(COPD);diagnose pulmonary embolism(PE)and distinguish it from exacerbations of chronic obstructive pulmonary disease;judge the adequacy of chest compressions in cardiac arrest and detect return of spontaneous circulation;estimate changes in cardiac output;predict fluid responsiveness;and assist in metabolic assessment and nutritional needs.PETCO2monitors are used to estimate arterial CO2 pressure(PaCO2),but appropriate use of this noninvasive method of assessing blood gases in ventilated patients remains unclear.METHODS This was an observational study conducted on arterial blood gases in adult patients with respiratory failure admitted to the Intensive Care Unit(ICU),between June and November in 2015.Samples were immediately analyzed for PaCO2 using a blood gas analyzer.The arterial to end-tidal CO2 gradient was determined.The PETCO2 was measured using an end-tidal CO2 analyzer,on the expiratory side of the circuit's endotracheal tube connector.After proper calibration and an equilibration time of 20 minutes with stable hemodynamic and respiratory variables,PETCO2 were determined and the highest reading was recorded.Patients who were undergoing one of the mechanical ventilation methods such as;assist/control(A/C),synchronized intermittent mandatory ventilation(SIMV),and Spontaneous(SPONT)were enrolled in this study.RESULTS A total of 225 arterial blood gases were obtained from the 104 patients.In each of these modes the ETCO2 was generally lower than the PaCO2.There is a positive correlation between PaCO2 and ETCO2 undifferentiated modes(r=0.703,Y= 11.08 + 0.77x).A positive correlation was found with each of the SIMV and SPONT modes,indicating statistical significance but A/C mode.The relationship between PaCO2 and ETCO2 in COPD,trauma,cerebrovascular disease and severe pneumonia patients is shown appositive correlation(r=0.759,0.639,0.533 and 0.564,respectively).There is a significant correlation whether PaCO2/FiO2<200mmHg(r= 0.692,P<0.001)or ?200 mmHg(r=0.710,P<0.001).CONCLUSIONS The results of this study shows that PETCO2 monitoring accurately reflects PaCO2 during mechanical ventilation.A positive correlation was found with each of modes,disease category and PaCO2/FiO2.OBJECTIVE "Hypercapnic encephalopathy"(HE)is a heterogeneous and potentially reversible wide spectrum of neurological alterations(from cognitive defects,psychomotor agitation and confusion with asterixis to soporous status,delirium and coma)occurring in the presence of acute respiratory failure(ARF)with severe decompensated respiratory hypercapnic acidosis.Invasive mechanical ventilation is currently recommended as the gold-standard technique for the treatment of patients with an acute exacerbation of COPD(AECOPD)and HE.Mechanical ventilation supported basic minute ventilation,and caused PaCO2 to recovery into stable level.PaCO2 should not descend too much and induce respiratory alkalosis.Currently,there is no ways to monitor PaCO2 downturn trend and mechanical ventilation strategy cannot control rate of decay.End-tidal carbon dioxide(PETCO2)monitoring refers to the noninvasive measurement of exhaled carbon dioxide and is most useful when applied directly to patient care.It is considered as a surrogate for the PaCO2.There is strong correlation between PaCO2 and PETCO2 in healthy adults.In this study,we will observe the correlation between PaCO2 and PETCO2,monitor PETCO2 downswing in early used of mechanical ventilation and try to explore PETCO2-directed target strategy for ventilator settings.METHODS This prospective and observational study was performed between October 2015 and October 2016 in Respiratory ICU(RICU).All patients with AECOPD and hypercapnic encephalopathy received invasive mechanical ventilation.(1)Samples were immediately analyzed for PaCO2 using a blood gas analyzer.The PETCO2 was measured using an end-tidal CO2 analyzer at the same time.Correlation between PaCO2 and PETCO2 was analyzed.(2)After HE patients were intubated and received mechanical ventilation,PETCO2 were monitoring continually.After proper calibration and an equilibration time of 20 minutes with stable hemodynamic and respiratory variables(fluctuating margin?±2mmHg),PETCO2 were determined and the highest reading was recorded per 2 minutes.(3)After mechanical ventilation therapy for 24-36h,patients were in controlled ventilation and PETCO2 was stably.Change the breathing frequency and adjust minute ventilation from initial value to 4L/min,then minute ventilation rise to 10L/min and was recovered to initial breathing frequency.Correlation between minute ventilation and PETCO2 was analyzed.RESULTS(1)A total of 70 arterial blood gases were obtained from the 24 patients.There is a positive correlation between PaCO2 and ETCO2 undifferentiated modes(r=0.761,Y= 14.13 + 0.80x).A positive correlation was found in each of the SIMV and SPONT modes,indicating statistical significance but A/C mode(r=-0.016,P=0.980).There is a significant correlation whether PaCO2/FiO2<200mmHg(r=0.765,P<0.001)or ?200 mmHg(r=0.759,P<0.001).(2)Night patients received PETCO2 monitor continuously at early stage of mechanical ventilation.PETCO2 level fell rapidly and reached stable state in 20-60minutes.The higher of initial PETCO2 value,the more time to stable state,but lower than one hour.Downtrend of PETCO2 was calculated by the mechanical ventilation time of fitting curve(Y =PETCO2base+b1x+b2X2).(3)A total of 58 arterial blood gases were obtained from the 12 patients.PETCO2 become stable after 1-2 minutes in each adjusted respiratory rate.There is a significant negative correlation between minute ventilation and PETCO2(r=-0.560,Y= 66.82-3.06 x).CONCLUSIONS There is a significant correlation between PaCO2 and ETCO2.PETCO2 could prediction PaCO2 downtrend at early stage of mechanical ventilation and provide a basis for preventing excessive ventilation and adjust ventilator setting.