Objective To evaluate the effect of auto adjusted triggering mechanism on the triggering balance of sensitivity and anti-interference in non invasive ventilator field. Methods Taking the breathing simulator as the experimental platform, for the same ventilator, the experiments of "automatic adjustment mode" and "manual adjustment mode" were carried out in a self-control manner, comparing the sensitivity and anti-interference indexes of the experimental group and the control group in the triggering stage. The results were statistically analyzed. Results In case of large air leakage, for ventilator of "A40", the group of "automatic adjustment mode" presented auto-triggered cycle and the group of "manual adjustment mode" (the inspiratory trigger sensitivity was adjusted to 5 to 9 L/min) could provide breathing assistance ventilation. While for ventilator of "VENT", both the group of "automatic adjustment mode" and the group of "manual adjustment mode" (the inspiratory trigger sensitivity was adjusted to 1 to 8 arbitrary unit) appear auto-triggered cycle. In case of medium air leakage, for ventilator of "A40", the trigger delay time, trigger pressure and trigger work of the "manual adjustment mode" group (the inspiratory trigger sensitivity was adjusted to 3 to 5 L/min) were significantly less than those of the "automatic adjustment mode" group, and the trigger delay time, trigger work of the "manual adjustment mode" group (the inspiratory trigger sensitivity was adjusted to 8 to 9 L/min) were significantly higher than those of the "automatic adjustment mode" group; While for ventilator of "VENT", compared with the inspiratory trigger sensitivity of the "automatic adjustment mode" group and the "manual adjustment mode" group (the inspiratory trigger sensitivity was adjusted to 4 arbitrary unit), the trigger delay time, trigger pressure and trigger work were not statistically significant. In case of small air leakage, for ventilator of "A40", the trigger delay time and trigger work of the "manual adjustment mode" group (the inspiratory trigger sensitivity was adjusted to 2 to 6 L/min) were significantly less than those in the "automatic adjustment mode" group, and the trigger pressure of "manual adjustment mode" group (the inspiratory trigger sensitivity was adjusted to 2 to 5 L/min and 7 L/min) was significantly lower than that of "automatic adjustment mode" group. While for ventilator of "VENT", the trigger delay time, trigger pressure and trigger work of the "manual adjustment" group (the inspiratory trigger sensitivity was adjusted to 1 to 2 arbitrary unit) were less than those of the experimental group, and they were statistically significant. Conclusions In case of large air leakage, ventilator of "VENT" can not provide breathing assistance ventilation no matter which inspiratory trigger mode. While ventilator of "A40" should be used the "manual adjustment mode", and adjust the inspiratory trigger sensitivity to the less sensitive arbitrary unit to increase its performance of anti-interference. In case of medium air leakage, for both ventilator of "A40" and ventilator of "VENT", it is better to use "automatic adjustment" mode for breathing assistance ventilation. In case of small air leakage, for both ventilator of "A40" and ventilator of "VENT", it is better to use "manual adjustment" mode for breathing assistance ventilation and we should adjust the inspiratory trigger sensitivity to the higher sensitive arbitrary without auto-triggered cycle.
ObjectiveTo investigate the effect of noninvasive ventilation (NIV) in patients with myasthenic crisis after thymectomy. Methods31 myasthenic crisis patients after thymectomy who initially used NIV,admitted in the First Affiliated Hospital of Guangzhou Medical University between January 2011 and June 2013,were analyzed retrospectively.They were assigned to two groups according to the successful application of NIV or not,with 13 patients in the NIV success group and 18 patients in the NIV failure group.The related factors including gender,age,APACHEⅡ score when admitted to ICU,the results of blood gas analysis before NIV,thymoma or not,the history of myasthenic crisis,the history of chronic lung disease,and minute ventilation accounted for the largest percentage of predicted value (MVV%pred)were analyzed. ResultsThere were no significant differences in age,gender,or APACHEⅡ score between two groups (P>0.05).The PaCO2 in the NIV success group was lower than that in the NIV failure group.The preoperative MVV%pred in the NIV success group was higher than that in the NIV failure group.There were no significant differences between two groups in pH,PO2,thymoma or not,the history of myasthenic crisis,or the history of chronic lung disease (P>0.05).If using the 45 mm Hg as the cut-off value of PaCO2 and 60% as the cut-off value of MVV%pred,the incidence of PaCO2<45 mm Hg and the incidence of MVV%pred>60% were higher in the NIV success group than those in the NIV failure group (84.6% vs.33.3%, P<0.05;100% vs. 55.6%,P<0.05).Logistic regression analysis revealed that PaCO2<45 mm Hg was an independent influence factor for successful application of NIV in patients with myasthenic crisis after thymectomy. ConclusionPaCO2<45 mm Hg can be a predictor of successful application of NIV in patients with myasthenic crisis after thymectomy.For the patients underwent NIV whose PaCO2<45 mm Hg or MVV%pred<60%,the clinician should predict the possibility of failure and prepared for intubation.
Objective The risk factors of noninvasive positive pressure ventilation (NPPV) in the treatment of acute exacerbation of chronic obstructive pulmonary disease (AECOPD) combined with failure of respiratory failure were identified by meta-analysis, so as to provide a basis for early clinical prevention and treatment failure and early intervention. Methods PubMed, The Cochrane Library, EMbase, China National Knowledge Infrastructure, Wanfang, VIP and CBM Data were searched to collect studies about risk factors about failure of noninvasive positive pressure ventilation in AECOPD and respiratory failure published from January 2000 to January 2021. Two researchers independently conducted literature screening, literature data extraction and quality assessment. Meta-analysis was performed on the final literature obtained using RevMan 5.3 software. Results Totally 19 studies involving 3418 patients were recruited. The statistically significant risk factors included Acute Physiology and Chronic Health Evaluation (APACHEⅡ) score, pre-treatment PCO2, pre-treatment pH, Glasgow Coma Scale (GCS), respiratory rate (RR) before treatment, body mass index (BMI), age, C-reactive protein (CRP), renal insufficiency, sputum disturbance, aspiration of vomit. Conclusions High APACHE-Ⅱ score, high PCO2 before treatment, low pH value before treatment, low GCS score, high RR before treatment, low BMI, advanced age, low albumin, high CRP, renal insufficiency, sputum disturbance, and vomit aspiration were the risk factors for failure of respiratory failure in patients with COPD treated by NIPPV. Failure of non-invasive positive pressure ventilation in COPD patients with respiratory failure is affected by a variety of risk factors, and early identification and control of risk factors is particularly important to reduce the rate of treatment failure.
Objective To explore the effects of enteral tube feeding on moderate AECOPD patients who underwent noninvasive positive pressure ventilation ( NPPV) . Methods Sixty moderate AECOPD patients with NPPV admitted from January 2009 to April 2011 were recruited for the study. They were randomly divided into an enteral tube feeding group (n=30) received enteral tube feeding therapy, and an oral feeding group (n=30) received oral feeding therapy. Everyday nutrition intake and accumulative total nutrition intake in 7 days, plasma level of prealbumin and transferrin, success rate of weaning, duration of mechanical ventilation, length of ICU stay, rate of trachea cannula, and mortality rate in 28 days were compared between the two groups. Results Compared with the oral feeding group, the everyday nutrition intake and accumulative total nutrition intake in 7 days obviously increased (Plt;0.05) , while the plasma prealbumin [ ( 258.4 ±16.5) mg/L vs. (146.7±21.6) mg/L] and transferrin [ ( 2.8 ±0.6) g/L vs. ( 1.7 ±0.3) g/L] also increased significantly after 7 days in the enteral tube feeding group( Plt;0.05) . The success rate of weaning ( 83.3% vs. 70.0%) , the duration of mechanical ventilation [ 5. 6( 3. 2-8. 6) days vs. 8. 4( 4. 1-12. 3) days] , the length of ICU stay [ 9. 2( 7. 4-11. 8) days vs. 13. 6( 8.3-17. 2) days] , the rate of trachea cannula ( 16. 6% vs. 30. 0% ) , the mortality rate in 28 days ( 3. 3% vs. 10. 0% ) all had significant differences between the enteral tube feeding group and the oral feeding group. Conclusions For moderate AECOPD patients with NPPV, enteral tube feeding can obviously improve the condition of nutrition and increase the success rate of weaning, shorten the mechanical ventilation time and the mean stay in ICU, decrease the rate of trachea cannula and mortality rate in 28 days. Thus enteral tube feeding should be preferred for moderate AECOPD patients with NPPV.
Without artificial airway though oral, nasal or airway incision, the bi-level positive airway pressure (Bi-PAP) has been widely employed for respiratory patients. In an effort to investigate the therapeutic effects and measures for the respiratory patients under the noninvasive Bi-PAP ventilation, a therapy system model was designed for virtual ventilation experiments. In this system model, it includes a sub-model of noninvasive Bi-PAP respirator, a sub-model of respiratory patient, and a sub-model of the breath circuit and mask. And based on the Matlab Simulink, a simulation platform for the noninvasive Bi-PAP therapy system was developed to conduct the virtual experiments in simulated respiratory patient with no spontaneous breathing (NSB), chronic obstructive pulmonary disease (COPD) and acute respiratory distress syndrome (ARDS). The simulated outputs such as the respiratory flows, pressures, volumes, etc, were collected and compared to the outputs which were obtained in the physical experiments with the active servo lung. By statistically analyzed with SPSS, the results demonstrated that there was no significant difference (P > 0.1) and was in high similarity (R > 0.7) between the data collected in simulations and physical experiments. The therapy system model of noninvasive Bi-PAP is probably applied for simulating the practical clinical experiment, and maybe conveniently applied to study the technology of noninvasive Bi-PAP for clinicians.
Objective To investigate the influence of pulmonary infection on noninvasive ventilation ( NIV) therapy in hypercapnic acute respiratory failure ( ARF) due to acute exacerbation of chronic obstructive pulmonary disease ( AECOPD) , and evaluate the predictive value of simplified version of clinical pulmonary infection score ( CPIS) for the efficacy of NIV therapy in ARF patients with AECOPD. Methods Eighty-four patients with ARF due to AECOPD were treated by NIV, and were divided into a successful group and an unsuccessful group by the therapeutic effect of NIV. The CPIS and simplified version of CPIS between two groups was compared. The predictive value of simplified version of CPIS for the efficacy of NIV wasevaluated using ROC curve analysis. Results The CPIS and the simplified version of CPIS of the successful treatment group ( 4. 0 ±2. 8, 3. 2 ±2. 4) were lower than those of the unsuccessful group ( 8. 0 ±2. 1, 7. 2 ±1. 8) significantly ( P =0. 006, 0. 007) . The area under ROC curve ( AUC) of CPIS and simplified version of CPIS were 0. 884 and 0. 914 respectively, the cut oint of CPIS and simplified version of CPIS were 6 ( sensitivity of 78. 0% , specificity of 91. 2% ) and 5 ( sensitivity of 80. 0% , specificity of 91. 2% ) respectively. Conclusions The level of pulmonary infection is an important influencing factor on the therapeutic effect of NIV in patients with ARF due to AECOPD. Simplified version of CPIS is a helpful predictor for the effect of NIV on ARF of AECOPD.
ObjectiveTo investigate the feasibility of electroencephalography (EEG) power spectrum analysis monitoring noninvasive intracranial pressure (ICP). MethodsBetween September 2008 and May 2009, the EEG signals were recorded in 62 patients (70 cases/times) with central nervous system (CNS). By using self-designed software, EEG power spectrum analysis was conducted and pressure index (PI) was calculated automatically. ICP was measured by lumbar puncture (LP). ResultsThe mean ICP was (239.74±116.25) mm H2O (70-500 mm H2O, 1 mm H2O=0.009 8 kPa), and 52.9% of patients had increased ICP. The mean PI was 0.29±0.20 (0.02-0.85). The Spearman rank test showed that there was a significant negative correlation between PI and ICP (rs=-0.849, P<0.01). The data from the patients with diffuse lesions of CNS and focal lesions were analyzed separately; the results showed there were significant negative correlations between PI and ICP in both groups (rs=-0.815, -0.912; P<0.01). ConclusionThe PI obtained from EEG analysis is correlated with ICP. Analysis of specific parameters from EEG power spectrum might reflect the ICP. Further research should be carried out.
Objective This is a meta-analysis of the efficacy of noninvasive ventilation (NIV) with helmet compared to NIV with face mask in patients with acute respiratory failure (ARF). Methods " Helmet, face mask or facial mask” and " mechanical ventilation or noninvasive ventilation” were used as key words both in Chinese and English to search all the trials in PubMed, OVID, Embase, Scopus and Cochrane Library, websites, reference lists of articles, CNKI and Wanfang Database from inception to December 2016. Two reviewers independently assessed the methodological quality of the trials and extracted information. Revman 5.3 was used for data analysis. Results Ten randomized controlled trials (RCTs) and six case-control trials were included. NIV with a helmet reduced the intubation rate (OR=0.35, 95%CI 0.24 to 0.51, P<0.000 01), in-hospital mortality rate (OR=0.51, 95%CI 0.34 to 0.76, P=0.001), and NIV-related complications (OR=0.10, 95%CI 0.06 to 0.15, P<0.000 01) compared to NIV with face mask. There was no significant difference in gas exchange between two groups. In the subgroup analysis, types of ARF and ventilation mode did not affect the intubation rate and the complications relevant to NIV, but NIV with helmet mainly decreased the in-hospital mortality of the patients with hypoxemic ARF or pressure support ventilation. Conclusions NIV with a helmet can decrease the endotracheal intubation rate, in-hospital mortality, and NIV-related complications of the patients with ARF. And helmet is as effective as face mask in improving the gas exchange. However, larger or multicenter RCTs are needed to analyze the role of NIV with a helmet in this condition.
ObjectiveTo explore the reason of failure in noninvasive positive pressure ventilation (NPPV) for treatment of postoperative hypoxemia, in order to better guide use of NPPV after cardiac surgery. MethodsWe retrospectively analyzed the clinical data of 64 patients after heart surgery with undergoing NPPV treatment due to hypoxemia in our hospital between January 2012 and December 2013 year.There were 49 males and 15 females at age of 28 to 87 years. There were 17 patients with NPPV failure. The related factors for failure of NPPV were analyzed. ResultsFactors associated with failure of NPPV included smoking history, preoperative pulmonary function abnormalities, blood transfusion amount > 1 000 ml, simplified acute physiology score Ⅱ(SAPS Ⅱ) before NPPV > 35 points, oxygenation index (PaO2/FiO2) < 100 mm Hg before NPPV, PaO2/FiO2 < 150 mm Hg after NPPV treatment for 1 h, mechanical ventilation time > 72 h at the first time, and pneumonia (P < 0.05). The SAPS Ⅱ > 35 points before NPPV and pneumonia were the independent risk factors for NPPV treatment failure for postoperative hypoxemia. ConclusionPostoperative NPPV for heart disease should be according to the cause of low oxygen and severity. For patients with SAPS less than 35 points before NPPV or patients with pneumonia, NPPV should not be used. In the process of NPPV, if clinical effect is not satisfied, it should be converted to invasive ventilation immediately.
Objective To systematically review the efficacy of noninvasive positive pressure ventilation (NPPV) by helmet in adults with acute respiratory failure. Methods Randomized controlled trials (RCTs) or cohort studies about noninvasive positive pressure ventilation (NPPV) by helmet in adults with acute respiratory failure were retrieved in PubMed, The Cochrane Library (Issue 11, 2016), Web of Science, EMbase, CBM, CNKI and WanFang Data databases from inception to November 2016. Two reviewers independently screened literature, extracted data and assessed the risk of bias of included studies. Stata 12.0 software was then used to perform meta-analysis. Results A total of eight studies were included. The results of meta-analysis showed that, NPPV by helmet could significantly reduce the carbon dioxide partial pressure (cohort study: SMD=–0.46, 95%CI –0.75 to –0.18, P=0.001), tracheal intubation rate (RCT: OR=0.36, 95%CI 0.17 to 0.77, P=0.008) and hospital mortality (RCT: OR=0.48, 95%CI 0.24 to 0.98, P=0.044), improve the positive end expiratory pressure (RCT: SMD=1.27, 95%CI 0.87 to 1.67, P<0.05) and respiratory status (RCT: SMD=–0.45, 95%CI –0.81 to –0.08,P=0.017). There was no significant difference in the duration of NPPV(cohort study: OR=–0.20, 95%CI –0.50 to 0.09, P=0.177; RCT: OR=–0.24, 95%CI –0.86 to 0.38, P=0.445). Conclusion NPPV by helmet can reduce the carbon dioxide partial pressure, tracheal intubation rate, hospital mortality and improve the positive end expiratory pressure, respiratory status. But the effects in the duration of NPPV and oxygenation index are uncertain. Due to limited quality and quantity of the included studies, more high quality studies are needed to verify above conclusion.