It is difficult to select the appropriate ventilation mode in clinical mechanical ventilation. This paper presents a nonlinear multi-compartment lung model to solve the difficulty. The purpose is to optimize respiratory airflow patterns and get the minimum of the work of inspiratory phrase and lung volume acceleration, minimum of the elastic potential energy and rapidity of airflow rate changes of expiratory phrase. Sigmoidal function is used to smooth the respiratory function of nonlinear equations. The equations are established to solve nonlinear boundary conditions BVP, and finally the problem was solved with gradient descent method. Experimental results showed that lung volume and the rate of airflow after optimization had good sensitivity and convergence speed. The results provide a theoretical basis for the development of multivariable controller monitoring critically ill mechanically ventilated patients.
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 investigate the clinical characteristics, risk factors and perioperative outcome of prolonged mechanical ventilation (PMV) in elderly patients undergoing coronary artery bypass grafting (CABG). Methods The data of elderly patients receiving CABG in the Nanjing First Hospital from January 2013 to June 2019 were collected. All patients were divided into a control group and a PMV group according to whether ventilation time≥24 h.The clinical characteristics and risk factors of PMV were compared between the two groups. Variables were 1∶1 balanced through propensity score matching (PSM) and perioperative outcomes of two groups was analyzed. Results Finally 956 patients were collected, including 187 in the PMV group and 769 in the control group. There were 586 males and 370 females aged 70-94 (74.3±3.5) years. Compared with the control group, the PMV group had higher rates of smoking, preoperative renal impairment, intraoperative blood transfusion and intra-aortic balloon pump (IABP) implantation, worse cardiac function, lower glomerular filtration rate and ejection fraction, larger left atrial diameter, longer cardiopulmonary bypass time and aortic cross-clamping time (P<0.05). There was no statistical difference in other clinical data between the two groups (P>0.05). Binary multivariate logistic regression analysis showed that females, smoking, chronic obstructive pulmonary disease, left ventricular ejection fraction≤56.0%, cardiopulmonary bypass time>106.0 min, IABP implantation and intraoperative blood transfusion were independent risk factors for PMV in elderly patients. After PSM, there were 146 patients in the control group and the PMV group, respectively. The PMV group had longer ICU stay and length of hospital stay and more drainage volume compared with the control group (all P<0.05). There was no statistical difference in perioperative mortality or other complications between the two groups (all P>0.05). ConclusionThere are a lot of factors associated with PMV of the elderly patients undergoing on-pump CABG. In order to establish a complete and formal PMV prediction model, clinicians can make a further step of assessment according to perioperative elements, and improve the prognosis of such patients.
Objective To identify the preoperative risk factors for prolonged mechanical ventilation (PMV) after pulmonary thromboendarterectomy (PTE). MethodsThe clinical data of patients who underwent PTE from December 2016 to August 2021 in our hospital were retrospectively analyzed. The patients were divided into two groups according to the postoperative mechanical ventilation time, including a postoperative mechanical ventilation time≤48 h group (≤48 h group) and a postoperative mechanical ventilation time>48 h (PMV) group (>48 h group). Univariable and logistic regression analysis were used to identify the preoperative risk factors for postoperative PMV. ResultsTotally, 90 patients were enrolled in this study. There were 40 patients in the ≤48 h group, including 30 males and 10 females, with a mean age of 45.48±12.72 years, and there were 50 patients in the >48 h group, including 29 males and 21 females, with a mean age of 55.50±10.42 years. The results showed that in the ≤48 h group, the median postoperative ICU stay was 3.0 days, and the median postoperative hospital stay was 15.0 days; in the >48 h group, the median postoperative ICU stay was 7.0 days, and the median postoperative hospital stay was 20.0 days. The postoperative PMV was significantly correlated with tricuspid annular plane systolic excursion (TAPSE) [OR=0.839, 95%CI (0.716, 0.983), P=0.030], age [OR=1.082, 95%CI (1.034, 1.132), P=0.001] and pulmonary vascular resistance (PVR) [OR=1.001, 95%CI (1.000, 1.003), P=0.028]. ConclusionAge and PVR are the preoperative risk factors for PMV after PTE, and TAPSE is the preoperative protective factor for PMV after PTE.
Objective To explore the oxygen therapy effects of high-flow T-tube oxygen therapy on neurointensive care patients who have undergone tracheostomy and are undergoing mechanical ventilation while meeting the criteria for weaning from mechanical ventilation, especially in terms of controlling airway temperature and humidity, promoting mucus dilution, and reducing postoperative complications. MethodsCollected data from 50 neurointensive care patients who underwent tracheostomy and were on mechanical ventilation, meeting the criteria for weaning from mechanical ventilation, treated at West China Hospital of Sichuan University from September 2019 to September 2021. The three groups of patients had different weaning methods: a high-flow T-tube for weaning, a heat and moisture exchanger (artificial nose) for weaning, and a high-flow tracheal joint for weaning. The vital signs, dyspnea and blood gas analysis before and three days after weaning were collected. The primary outcomes were mechanical sputum excretion, postural drainage, phlegm-resolving drugs use, airway-related events (artificial airway blockage, artificial nose blockage, lung infection), stay in ICU (days), and death in ICU. Results Among the 50 patients, 28 were males and 22 were females. There were no significant differences in age, weight, height, gender, finger pulse oxygen saturation, heart rate, APACHEII score, sequential organ failure assessment, or Glasgow coma scale among the three groups (P>0.05). There was no statistical difference in the number of 72-hour mechanical sputum excretion or the use of phlegm-resolving drugs in the three groups (P=0.113, P=1.00). Conclusion The use of high-flow T-tube oxygen therapy in neurointensive care patients who have undergone tracheostomy, are on mechanical ventilation, and meet the criteria for weaning from mechanical ventilation can effectively control airway temperature and humidity, promote mucus dilution for better drainage, thereby reducing post-tracheostomy complications.
Perioperative mechanical ventilation plays a role in lung injury and postoperative pulmonary complications, yet a consensus in the literature concerning the key clinical question of how to best provide lung protection during mechanical ventilation in surgical patients is lacking. It is necessary to develop an expert consensus on perioperative mechanical ventilation suitable for Chinese anesthesiologists to better guide clinical practice. The experts from the Anesthesia Committee of Chengdu Medical Association and the Chongqing Medical Association Anesthesiology Branch were organized by West China Hospital of Sichuan University to propose the question regarding the perioperative mechanical ventilation, and the current literature was then reviewed, and expert opinions were solicited to provide evidence-based guidance. Subsequently, the expert panel reached a consensus and formulated 28 recommendations with evidence of moderate to high quality using the modified Delphi method.
Objective To investigate the predictive value of mechanical power (MP) in the weaning outcome of adaptive mechanical ventilation plus intelligent trigger (AMV+IntelliCycle, simply called AMV) mode for acute respiratory distress syndrome (ARDS) patients. Methods From November 2019 to March 2021, patients with mild to moderate ARDS who were treated with invasive mechanical ventilation in the intensive care unit of the First Affiliated Hospital of Jinzhou Medical University were divided into successful weaning group and failed weaning group according to the outcome of weaning. All patients were treated with AMV mode during the trial. The MP, oral closure pressure (P0.1), respiratory rate (RR) and tidal volume (VT) of the two groups were compared 30 min and 2 h after spontaneous breathing trial (SBT). The correlation between 30 min and 2 h MP and shallow rapid respiratory index (RSBI) was analyzed by Pearson correlation. Receiver operating characteristic (ROC) curve was used to analyze the predictive value of 30 min MP in ARDS patients with AMV mode weaning failure. Results Sixty-eight patients were included in the study, 49 of them were successfully removed and 19 of them failed. There was no statistical significance in age, gender, body mass index, oxygenation index, acute physiology and chronic health evaluation Ⅱ score, reasons for mechanical ventilation (respiratory failure, sepsis, intracranial lesions, and others) between the two groups (all P>0.05). The MP, P0.1 and RR at SBT 30 min and 2 h of the successful weaning group was lower than those of the failed weaning group (all P<0.05), but the VT of the successful weaning group was higher than the failed weaning group (all P<0.05). There was a significant relation between the MP at SBT 30 min and 2 h and RSBI (r value was 0.640 and 0.702 respectively, both P<0.05). The area under ROC curve of MP was 0.674, 95% confidence interval was 0.531 - 0.817, P value was 0.027, sensitivity was 71.73%, specificity was 91.49%, positive predictive value was 0.789, negative predictive value was 0.878, optimal cutoff value was 16.500. The results showed that 30 min MP had a good predictive value for the failure of weaning in AMV mode in ARDS patients. Conclusion MP can be used as an accurate index to predict the outcome of weaning in ARDS patients with AMV mode.
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.
Since December 2019, severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection has gradually spread all over the world. With the implementation of class B infectious disease management policy for coronavirus disease 2019 (COVID-19), China has experienced a pandemic. For patients receiving a time-sensitive or emergency surgery, SARS-CoV-2 infection may increase the risk of postoperative pulmonary complications. An appropriate perioperative mechanical ventilation strategy, such as lung protective ventilation strategy, is particularly important for preventing postoperative pulmonary complications in patients undergoing general anesthesia. In addition, how to protect medical personnel from being infected is also the focus we need to pay attention to. This article will discuss the perioperative mechanical ventilation strategy for COVID-19 patients and the protection of medical personnel, in order to provide reference for the development of guidelines.
ObjectiveTo analyze the risk factors of myasthenia gravis crisis after thymectomy with myasthenia gravis (MG).MethodsSixty-five myasthenia gravis patients who had myasthenia crisis after thymectomy in Xuanwu Hospital, Capital Medical University from June 2006 to June 2019 were retrospectively enrolled, including 31 males and 34 females, aged 15-78 (45.7±17.8) years. The relationship between myasthenia crisis after thymectomy and surgical option, operation time, pathological type, et al. were anylyzed.ResultsOperation time and pathological type were the predictive factors of postoperative myasthenic crisis. The area under receiver operating characteristic curve (AUC) of MG type (Osserman) was 0.676, the cut-off value wasⅡB type, the sensitivity was 37.5%, the specificity was 90.5%, and the Youden’s index was 0.280. The AUC of thymoma stage (Masaoka) was 0.682, cut-off value was stageⅡ, sensitivity was 62.5%, specificity was 66.7%, and Youden’s index was 0.292. The AUC of blood loss was 0.658, the cut-off value was 90 mL, the sensitivity was 87.5%, the specificity was 69.6%, and the Youden’s index was 0.304.ConclusionPreoperative MG classification, pathological type, operation time and blood loss are the risk factors of postoperative myasthenic crisis. Therefore, adequate preoperative preparation, rapid and careful intraoperative operation and active postoperative management can reduce the occurrence of postoperative myasthenic crisis.