In the clinical practice, the mechanical ventilation is a very important assisting method to improve the patients' breath. Whether or not the parameters set for the ventilator are correct would affect the pulmonary gas exchange. In this study, we try to build an advisory system based on the gas exchange model for mechanical ventilation using fuzzy logic. The gas exchange mathematic model can simulate the individual patient's pulmonary gas exchange, and can help doctors to learn the patient's exact situation. With the fuzzy logic algorithm, the system can generate ventilator settings respond to individual patient, and provide advice to the doctors. It was evaluated in 10 intensive care patient cases, with mathematic models fitted to the retrospective data and then used to simulate patient response to changes in therapy. Compared to the ventilator set only as part of routine clinical care, the present system could reduce the inspired oxygen fraction, reduce the respiratory work, and improve gas exchange with the model simulated outcome.
Objective To compare the sequential efficacy of high-flow nasal cannula oxygen therapy (HFNC) with non-invasive mechanical ventilation (NIV). Methods Randomized controlled trials comparing the efficacy of NIV sequential invasive mechanical ventilation with HFNC were included in the Chinese Journal Full-text Database, VIP Journal database, Wanfang Database, Chinese Biomedical Literature Database, PubMed, Cochrane Library and Embase. Meta-analysis was performed using RevMan5.4 software. Results A total of 2404 subjects were included in 19 studies. Meta-analysis results showed that compared with NIV, HFNC had a statistically significant difference in reducing patients' re-intubation rate in invasive mechanical ventilation sequence [relative risk (RR)=0.65, 95% confidence interval (CI) 0.50 - 0.86, Z=3.10, P=0.002]. HFNC showed statistically significant difference compared with NIV in reducing lung infection rate (RR=0.40, 95%CI 0.21 - 0.79, Z=2.67, P=0.008). HFNC was significantly different from NIV in terms of length of stay in Intensive Care Unit (ICU) (MD=–5.77, 95%CI –7.64 - –3.90, Z=6.05, P<0.00001). HFNC was significantly different from NIV in improving 24 h oxygenation index (MD=13.16, 95%CI 8.77 - 17.55, Z=5.87, P<0.00001). There was no significant difference in ICU mortality between HFNC and NIV (RR=0.70, 95%CI 0.45 - 1.08, Z=1.61, P=0.11). Conclusion Compared with NIV, sequential application of HFNC in invasive mechanical ventilation can improve the reintubation rate and pulmonary infection rate to a certain extent, reduce the length of ICU stay and improve the 24 h oxygenation index, while there is no difference in ICU mortality, which is worthy of clinical application.
摘要:目的: 评价机械通气对胸腔内脉搏氧饱和度的影响。 方法 :以食道、气管和降主动脉作为胸腔内脉搏氧饱和度的监测位点,将改制后的氧饱和度探头分别固定于上述部位,并连接于同一监护仪上。纯氧通气,待上述氧饱和度容积波波形和读数稳定,停止机械通气30s。以录像的方式记录机械通气停止前后30 s内食道、气管和降主动脉SpO2容积波和读数的变化。同时记录舌SpO2。 结果 :机械通气时,食道、气管和降主动脉三个监测位点均可获得异常高大的SpO2容积波;停止通气时,异常高大的氧饱和度波形消失。食道、气管和降主动脉脉搏容积波变异率分别为112%,74%,302%。降主动脉脉搏容积波的变异率明显高于食道和气管( 〖WTBX〗P ＜005)。机械通气停止前后30s内食道、气管和降主动脉的SpO2读数变化无显著差异(〖WTBX〗P ＞005)。 结论 :机械通气对胸腔内食道、气管和降主动脉氧饱和度读数无影响,主要影响是脉搏容积波。且各位点间脉搏氧容积波受呼吸的影响不同。Abstract: Objective: To investigate the impact of mechanical ventilation on pulse oximetry in thoracic cavity. Methods : After dogs anesthesia induction and thoracotomy, pulse oximeters were simultaneously placed at esophagus, trachea, and descending aorta, and connected with the same monitor for SpO2 monitoring. During ventilation with 100% oxygen, the mechanical ventilator was temporarily switched off for 30 seconds after high quality PPG waveforms and SpO2 readings were obtained. SpO2 signals and readings from esophagus (SeO2), trachea (StraO2), descending aorta (SDAO2) shown on the monitoring screen were recorded by the SONY video before and after stopventilation. And StonO2 were also recorded. Results : Abnormally largeamplitude PPG waves were found in normal waves at monitoring sites of esophagus, trachea, and descending aorta in all animals during ventilation; however, they disappeared without ventilator. The variation rate in ventilationinduced PPG amplitude were 112%, 74%, 302% at esophagus, trachea and descending aorta respectively. The PPG amplitude variation rate from SDAO2 was higher than that from SeO2 and StraO2 (〖WTBX〗P ＜005). However, the SpO2 readings obtained from pulse oximetries in all sites were no significantly statistical difference within 30s before and after temporarily stopventilation (〖WTBX〗P ＞005). Conclusion : Abnormally amplitude PPG waveforms from oximetry probe placed at esophagus, trachea, and descending aorta were induced by ventilation. The Variation rate in ventilationinduced PPG amplitude was various at different monitoring sites. The SpO2 readings from esophagus, trachea, and descending aorta were not significantly contaminated by ventilation.
Objective To evaluate the relationship between sublingual microcirculation differences and weaning success rate and prognosis in elderly patients with severe pneumonia. Methods A retrospective observation cohort study was conducted. Forty-two elderly patients with severe pneumonia who underwent mechanical ventilation in the intensive care unit of Sir Run Run Hospital, Nanjing Medical University from February 2022 to August 2022 were recruited in the study. They were divided into a high-flow nasal cannula oxygen group (HFNC group, n=33) and a non-invasive positive pressure ventilation group (NIPPV group, n=9) according to the mode of post-weaning ventilation. The differences of N-terminal brain natriuretic peptide precursor (NT-proBNP), cardiac index (CI) and sublingual microcirculation indexes between the two groups were analyzed. The receiver operating characteristic (ROC) curve was used to analyze the predictive value of each parameter on weaning success rate and case fatality rate. Results Compared with the NIPPV group, CI, propotion of perfused vessels (PPV) and perfused vessel density (PVD) were higher, and NT-proBNP and total vessel density (TVD) were lower in the HFNC group (all P<0.05). The prediction value of PPV combined with PVD was the largest, with area under the ROC curve (AUC) of 0.875, sensitivity of 75.8%, specificity of 88.9%. CI, NT-proBNP, CI combined with NT-proBNP, PPV, PVD all had predictive value. Compared with the death group, the survival group had higher CI, central venous-to-arterial carbon dioxide difference [P(v-a)CO2] and PPV. For the prediction value of weaning success, CI combined with NT-proBNP had the largest predictive value, with AUC of 0.919, sensitivity of 81.8%, specificity of 100.0%, followed by CI. NT-proBNP, PPV, PVD, PPV combined with PVD all had predictive value. Compared with the death group, the survival group had higher CI, P(v-a)CO2 and PPV (all P<0.05). For predictive value assessment of 28-day survival rate, CI plus PPV had the largest AUC of 0.875, with sensitivity of 69.4%, and specificity of 100.0%. CI, P(v-a)CO2 and PPV all have predictive value. Conclusions Both CI and PPV can be used as predictors of weaning success rate and survival rate. PPV combined with PVD is an ideal predictor of survival rate.
Pressure-support ventilation (PSV) is a form of important ventilation mode. Patient-ventilator synchrony of pressure support ventilation can be divided into inspiration-triggered and expiration-triggered ones. Whether the ventilator can track the patient's inspiration and expiration very well or not is an important evaluating item of the performance of the ventilator. The ventilator should response to the patient's inspiration effort on time and deliver the air flow to the patient under various conditions, such as different patient's lung types and inspiration effort, etc. Similarly, the ventilator should be able to response to the patient's expiration action, and to decrease the patient lung's internal pressure rapidly. Using the Active Servo Lung (ASL5000) respiratory simulation system, we evaluated the spontaneous breathing of PSV mode on E5, Servo i and Evital XL. The following parameters, the delay time before flow to the patient starts once the trigger variable signaling the start of inspiration, the lowest inspiratory airway pressure generated prior to the initiation of PSV, etc. were measured.
Objective To investigate the clinical significance of lateral position ventilation in the treatment of invasive ventilation in patients with acute exacerbations of chronic obstructive pulmonary disease (AECOPD). Methods From October 2014 to December 2016, 60 eligible patients with AECOPD who meeting the inclusion criteria were randomly assigned to an intervention group (n=30) or a control group (n=30). Expectorant, antiasthmatic, anti-infective, invasive ventilation, bronchoscopy, analgesic sedation, invasive-noninvasive sequential ventilation, nutritional support, intensive care and other treatment were conducted in two groups, but lateral position ventilation was subsequently performed in the intervention group and the control group used half lateral position. Outcome measurements included pH, PaO2/FiO2, arterial partial pressure of carbon dioxide (PaCO2), heart rate (HR), respiratory rate (R) and air way resistance (Raw) before and one day after invasive ventilation, and duration of control of pulmonary infection (PIC), invasive mechanic ventilation (IMV), mechanic ventilation (MV) and intensive care unit (ICU) stay. Results Compared with before ventilation, the levels of PaO2/FiO2, PaCO2, HR, R and Raw were significantly changed in two groups after ventilation (P<0.05). One day later after ventilation, pH [interventionvs. control: (7.43±0.07) vs. (7.37±0.11)], PaO2/FiO2[(253.52±65.33) mm Hg (1 mm Hg=0.133 kPa) vs. (215.46±58.72) mm Hg] and PaCO2 [(52.45±7.15) mm Hg vs. (59.39±8.44) mm Hg] were statistically significant (P<0.05), but no significant difference was found in HR, R or Raw between two groups (P>0.05). Compared with the control group, PIC [(3.7±1.4) daysvs. (5.3±2.2) days], IMV [(4.0±1.5) days vs. (6.1±3.0) days], MV [(4.7±2.0) days vs. (7.3±3.7) days] and ICU stay [(6.2±2.1) days vs. (8.5±4.2) days] were significantly decreased (P<0.05) in the intervention group. Conclusions In AECOPD patients, invasive ventilation using lateral position ventilation can significantly improve arterial blood gas index, decrease Raw, shorten the time of PIC, IMV, MV and ICU stay.
Objectives About 12.9-50% patients of SARS (Severe Acute Respiratory Syndrome), require brief mechanical ventilation (MV) to save life. All the reported principles and guidelines for therapy SARS were based on experiences from clinical treatments and facts of inadequacy. Neither prospective randomized controlled trials (RCT) nor other high quality evidences were in dealing with SARS. Our objective is to seek safe and rational non-drugs interventions for patients with severe SARS by retrospectively reviewing clinical studies about MV all over the world, which include clinical guidelines, systematic reviews (SR), Meta-analysis, economic researches and adverse events. Methods To search MEDLINE and Cochrane Library with computer. According to the standards of inclucion or exclusion, the quality of the article which as assessed, and relevant data which were extracted double checked. The Meta-analysis was conducted if the studies had no heterogeneity. Results 14 papers were eligible. Due to the significant heterogeneity between these studies, further Meta-analysis could not be conducted, and the authors’ conclusions were described only. Conclusions The outcome of PPV is better than that of VPV. Patients who underwent PPV had a significantly lower mortality than that of VPV. Of course, the volutrauma should be watched. With low tidal volume and proper PEEP, or decreased FiO2, even permissive hypercapnia, the mortality and length of stay were cut down. Non-invasive mechanical ventilation (NIMV) was effective in treating haemodynamical stable patients, minimizing complications and reducing medical staff infection. Patients with serious dyspnea with PaO2/FiO2lt;200, no profit of NIMV, or couldn’t tolerance hypoxaemia were unlikely to benefit from this technique and needed ventilation with endotracheal intubation. Prone position could improve PaO2/FiO2, NO maybe increased pulmonary perfusion, improved V/Q, and raised oxygenation. Furthermore, Inhaled NO sequentially (SQA) was better than Inhaled NO continuouly (CTA). Some studies implied that practice of protocol-directed weaning from mechanical ventilation implemented by nurses excelled that of traditional physician-directed weaning.
Objective To assess the risk factors associated with extubation failure in patients who had successfully passed a spontaneous breathing trial.Methods Patients receiving invasive mechanical ventilation for over 48 h were enrolled in the study，they were admitted into Emergency ICU of Zhongshan Hospital during May 2006 and Oct.2007.A spontaneous breathing trial was conducted by a pressure support of 7 cm H2O for 30 min.Clinical data were prospectively recorded for the patient receiving full ventilatory support before and after the spontaneous breathing trial.Regarding the extubation outcome，patients were divived into extubation success group and extubation failure group.Results A total of 58 patients with a mean（±SD） age of 69.4±12.7 years passed spontaneous breathing trial and were extubated.Extubation failure occurred in 11 patients（19%）.The univariate analysis indicated the following associations with extubation failure：elderly patients（78.1±7.9 years vs 67.4±15.1years，Plt;0.05），higher rapid shallow breathing index（RSBI） value（83±12 breaths·min-1·L-1 vs 68±19 breaths·min-1·L-1，Plt;0.05）and excessive respiratory tract secretions（54.5％ vs 21.3％，Plt;0.05）.Conclusion Among routinely measured clinical variables，elderly patients，higher RSBI value and amount of respiratory tract secretions were the valuable index for predicting extubation failure despite a successful spontaneous breathing trial.
ObjectiveTo investigate the association of preoperative serum uric acid (UA) levels with postoperative prolonged mechanical ventilation (PMV) in patients undergoing mechanical heart valve replacement.MethodsClinical data of 311 patients undergoing mechanical heart valve replacement in The First Affiliated Hospital of Anhui Medical University from January 2017 to December 2017 were retrospectively analyzed. There were 164 males at age of 55.6±11.4 years and 147 females at age of 54.2±9.8 years. The patients were divided into a PMV group (>48 h) and a control group according to whether the duration of PMV was longer than 48 hours. Spearman's rank correlation coefficient and logistic regression analysis were conducted to evaluate the relationship between preoperative UA and postoperative PMV. The predictive value of UA for PMV was undertaken using the receiver operating characteristic (ROC) curve..ResultsAmong 311 patients, 38 (12.2%) developed postoperative PMV. Preoperative serum UA level mean values were 6.11±1.94 mg/dl, while the mean UA concentration in the PMV group was significantly higher than that in the control group (7.48±2.24 mg/dl vs. 5.92±1.82 mg/dl, P<0.001). Rank correlation analysis showed that UA was positively correlated with postoperative PMV (rs=0.205, P<0.001). Multivariate logistic regression analysis demonstrated that preoperative elevated UA was associated independently with postoperative PMV with odds ratio (OR)=1.44 and confidence interval (CI) 1.15–1.81 (P=0.002). The area under the ROC curve of UA predicting PMV was 0.72, 95% CI0.635–0.806, 6.40 mg/dl was the optimal cut-off value, and the sensitivity and specificity was 76.3% and 63.0% at this time, respectively.ConclusionPreoperative elevated serum UA is an independent risk factor for postoperative PMV in patients undergoing mechanical heart valve replacement and has a good predictive value.
ObjectiveTo compare the effect of three different wetting liquid supply modes for noninvasive ventilation. MethodsNinety patients who accepted noninvasive ventilation between February and October 2014 were randomly divided into three groups with 30 in each. Patients in group A underwent humidification with traditional kettle water; those in group B received humidification by one-time automatic water supplying; and patients in group C received continuous infusion to add water for humidification. The wetting effect and humidification related situations among the three groups of patients were compared and analyzed. ResultsThere were statistically significant differences among the three groups in terms of wetting effect, comfort degree, water renewal cycle, working time and economic cost (P<0.05). Good wetting rate of group C was superior to group A and B (P<0.05), but there was no statistically significant difference between group A and B (P>0.05). Humidification comfort degree of group C was obviously higher than that in group A and B (P<0.05), while there was no statistically significant difference between group A and B (P>0.05). Water renewal cycle and working time of group C were significantly shorter than those in group A and B (P<0.05). At the same time, economic cost of group A and C was significantly less than that of group B (P<0.05), while there was no statistically significant difference between group A and C (P>0.05). ConclusionThe kind of continuous infusion for humidification in noninvasive ventilation has a good therapeutic effect for patients receiving airway wetting therapy, which is worthy of clinical popularization and application.