Objective To determine the usefulness of serial measurements of the rapid shallow breathing index ( f/VT , RSBI) as a predictor for successfully weaning of patients undergoing prolonged mechanical ventilation ( gt; 72 hours) . Methods 76 mechanically ventilated patients were prospectively analyzed. 120-min spontaneous breathing trial was conducted after the patients having fullfiled the traditional weaning criteria, and RSBI were continuously monitored by the ventilator at five time points ( 5, 15, 30,60, and 120 min) . A repeated measure of general linear model in SPSS 15.0 was conducted to analyze the data. Results 62 patients completed 120-minute spontaneous breath trial and in which 20 patients failed weaning. There was no significant difference of RSBI at five time points during weaning ( P gt;0. 05) . But thevariation trends of RSBI during weaning time were significant different between the successful weaning patients and the failed weaning patients ( P lt; 0. 05) . Conclusions In patients undergoing prolonged mechanical ventilation, the variation trend of RSBI is more valuable than single RSBI in the prediction ofsuccessful weaning.
Objective To evaluate the influence of tidal volume on the accuracy of stroke volume variation ( SVV) to predict volume state of pigs with ventilation.Methods Thirty-six healthy pigs were anesthetized after tracheal intubation and ventilated. With the envelope method, they were randomized into a normovolemia group, a hemaerrhagic shock group, and a hypervolemia group, with 12 pigs in each group. The pigs in the hemaerrhagic shock group were removed 20 percent of blood, and the pigs in the hypervolemia group received additional infusion of 20 percent 6% hydroxyethyl starch. In each group, ventilator settings were changed in a randomized order by changing VT [ VT = 5 mL/kg ( VT5 ) , VT =10 mL/kg ( VT10 ) , and VT =15 mL/kg ( VT15 ) ] . Hemodynamic measurements [ heart rate ( HR) , mean arterial boold pressure ( MAP) , systemic vascular resistance index ( SVRI) , cardiac index ( CI) , stroke volume index ( SVI) , intrathoracic blood volume index( ITBVI) , and SVV] were obtained after 10 minutes of stabilization. Results SVV was increased in the hemaerrhagic shock group comparing with the normovolemia group for VT10 [ ( 21 ±5) % vs. ( 11 ±2) % , P lt;0. 05] , but SVV was decreased in the hypervolemia group comparing with the normovolemia group [ ( 7 ±2) % vs. ( 11 ±2) % , P lt; 0. 05] . The variation tendency for VT15 was the same with VT10 , moreover SVV were all above 12% for the hemaerrhagic shock group, the normovolemia group, and the hypervolemia group [ ( 30 ±7) % , ( 19 ±3) % , and ( 15 ±4) % ] . There were no significant diffrences among the hemaerrhagic shock group, hypervolemia group and normovolemia group [ ( 8 ±6) % ,( 7 ±5) % , and ( 7 ±4) % , P gt; 0. 05] for VT5 . Conclusions SVV was a precise indicator of cardiac preload, but SVV was less sensitive to the changes of volume during low tidal volume ( 5 mL/kg) ventilation. The threshold of SVV for predicting fluid responsiveness maybe above 12% with a high tidal volume ( 15 mL/kg) ventilation.
Objective To evaluate the effects of midazolam intravenous drip combined with lidocaine via nebulization on patients during mechanical ventilation in intensive care unit ( ICU) . Methods 60 thoracic patients required postoperative mechanical ventilation in ICUwere randomized into 2 groups. The patients in therapeutic group received lidocaine 1 mg/kg via nebulization and midazolam intravenous drip 0. 1 mg·kg- 1·h- 1 . The patients in control group received 0. 9% NaCl 1 mg/kg via nebulization andmidazolam0. 1 mg·kg- 1 ·h- 1 . According to the scale of Ramsay, the additional midazolam and fentanyl were injected to maintain sedation and inhibit cough in both groups. During ventilation, calm score, the number and the severity of cough, the mean arterial pressure ( MAP) , heart rate ( HR) , and the consumption of midazolam and fentanyl were record. Results The number and severity of cough, the scale of MAP and HR in the therapeutic group were all significant lower than those in the control group ( P lt; 0. 05) . Theconsumption of midazolam and fentanyl in the therapeutic group were also significantly lower than that in the control group ( P lt; 0. 05) .Conclusion Midazolam intravenous drip combined with lidocaine via nebulization can reduce the side effects and requirement of sedative and opioids drug in ICU patients undergoing mechanical ventilation.
建立人工气道实施机械通气是治疗严重呼吸衰竭过程中挽救患者生命最常用的措施之一，然而通过人工气道的机械通气也增加了相关并发症发生的机会，如呼吸机相关性肺炎（VAP）等[1]。多数患者在应用呼吸机进行通气支持治疗中，当呼吸衰竭及其病因的病情缓解或明显改善时就可以解除人工气道和终止通气支持，但20%~30%的患者需要逐渐解除呼吸机的通气支持，谓之撤机（Weaning）[1]。尽管文献中撤机的定义略有不同，但主要指的是需要逐步减弱及停止通气支持和解除人工气道的一个时间过程。有慢性呼吸功能不全的患者撤机尤为困难，撤机困难患者的撤机时间可占总机械通气时间的40%[2]。机械通气时间延长与VAP发生率和病死率增加相关。一般来说，机械通气时间gt;3 d，VAP的发生率增加；机械通气时间gt;5 d，并发的VAP为晚发性医院获得性肺炎（HAP），其感染的病原体多为耐多药细菌，治疗难度加大，病死率高于早发性HAP。因此，对于机械通气患者来说，一旦建立人工气道实施有创通气，就应该积极创造条件，尽快撤机，去除人工气道。然而过快地降低和停止通气支持以及过早的气管拔管，可导致撤机失败和再插管。因此时机不成熟的撤机和延时撤机同样可造成机械通气时间过长，导致VAP发生率和病死率升高，以及医疗费用增加[2]。撤机的模式和方法有多种，但最佳的撤机方式仍有争议[1]。近年来无创通气（NIV）作为一种撤机方式用于临床已引起人们的兴趣和关注，但至今临床研究所得结论并未达到一致，NIV是否可以作为一种常规撤机方式用于临床尚无定论。本文通过总结近年来相关的临床研究，评价NIV用于机械通气撤机的可行性和利弊，探讨需进一步优化研究方案来解决的有关问题。
Objective To analyze the risk factors for duration of mechanical ventilation in critically ill patients. Methods Ninety-six patients who received mechanical ventilation from January 2011 to December 2011 in intensive care unit were recruited in the study. The clinical data were collected retrospectively including the general condition, underlying diseases, vital signs before ventilation, laboratory examination, and APACHEⅡ score of the patients, etc. According to ventilation time, the patients were divided into a long-term group ( n = 41) and a short-term group ( n = 55) . Risk factors were screened by univariate analysis, then analyzed by logistic regression method.Results Univariate analysis revealed that the differences of temperature, respiratory index, PaCO2 , white blood cell count ( WBC) , plasma albumin ( ALB) , blood urea nitrogen ( BUN) , pulmonary artery wedge pressure ( PAWP) , APACHEⅡ, sex, lung infection in X-ray, abdominal distention, and complications between two groups were significant.With logistic multiple regression analysis, the lower level of ALB, higher level of PAWP, lung infection in X-ray, APACHE Ⅱ score, abdominal distention, and complications were independent predictors of long-term mechanical ventilation ( P lt;0. 05) . Conclusion Early improving the nutritional status and cardiac function, control infection effectively, keep stool patency, and avoid complications may shorten the duration of mechanical ventilation in critically ill patients.
Objective To compare the humidification effect of the MR410 humidification system and MR850 humidification system in the process of mechanical ventilation. Methods Sixty-nine patients underwent mechanical ventilation were recruited and randomly assigned to a MR850 group and a MR410 group. The temperature and relative humidity at sites where tracheal intubation or incision, the absolute humidity, the sticky degree of sputum in initial three days after admission were measured. Meanwhile the number of ventilator alarms related to sputum clogging and pipeline water, incidence of ventilator associated pneumonia, duration of mechanical ventilation, and mortality were recorded. Results In the MR850 group,the temperature of inhaled gas was ( 36. 97 ±1. 57) ℃, relative humidity was ( 98. 35 ±1. 32) % , absolute humidity was ( 43. 66 ±1. 15) mg H2O/L, which were more closer to the optimal inhaled gas for human body.The MR850 humidification system was superior to the MR410 humidification system with thinner airway secretions, less pipeline water, fewer ventilator alarms, and shorter duration of mechanical ventilation. There was no significant difference in mortality between two groups. Conclusions Compared with MR410 humidification system, MR850 humidification system is more able to provide better artificial airway humidification and better clinical effect.
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.
Post operational recovery from cardiac surgery can be affected by many factors, including preoperative, intraoperative, and postoperative factors. Prolonged mechanical ventilation (PMV) , one of the major complications, has been widely accepted as a measure to evaluate the performance and outcomes of cardiac surgeries. Great progress has been made in the studies of risk factors contributing to PMV following cardiac surgeries in recent years. However, no clear and effective measures and approaches are available yet to prevent PMV. In this review, the authors try to summarize the risk factors that are associated with PMV throughout the perioperative period of cardiac surgery, as well as possible interventions when applicable.