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 observe the effects of exogenous pulmonary surfactant (PS) on ventilation-induced lung injury (VILI) in rats, and to investigate its possible mechanisms. Methods A total of 40 Wistar rats were divided into 4 groups with randomized blocks method: control group, high tidal volume (HV) group, VILI group, and PS group, with 10 rats in each group. The control group was subjected to identical surgical procedure but was never ventilated. After 30 min of mechanical ventilation (MV) with Vt 45 ml/kg, the rats in HV group were killed immediately; rats in the VILI group were continually ventilated for up to 150 min with Vt 16 ml/kg; in the PS group, 100 mg/kg of PS administered intratracheally and with the same settings as VILI group. Mean artery pressure (MAP), blood gas analysis, lung wet to dry weight ratios (W/D), thorax-lung compliance, and cell counts in bronchoalveolar lavage fluid (BALF) were determined. Nuclear factor-κB(NF-κB) activity in lungs was measured by enzyme-linked immunosorbent assay (ELISA), interleukin-8(IL-8) in serum and BALF was determined by radioimmunoassay (RIA). Pathological examination of the lung was performed. Results Injurious ventilation significantly decreased MAP and PaO2/FiO2, but increased NF-κB activity and W/D. MAP and PaO2/FiO2 improved, but NF-κB activity, IL-8 in serum and BALF, and cell counts in BALF reduced significantly in PS group compared with those in VILI group. Histological studies showed reduced pulmonary edema and atelectasis in the PS group. Conclusion PS administered intratracheally can suppress the increased activity of NF-κB induced by VILI, exogenous PS can be used to treat VILI.
ObjectiveTo investigate the risk factors associated with failure of weaning from invasive mechanical ventilation in gerontal patients with acute exacerbation of chronic obstructive pulmonary disease (AECOPD).
MethodsA retrospective study was conducted on 76 patients aged 65 years and older with AECOPD who received invasive mechanical ventilation and met the weaning criteria from July 2012 to June 2014. The subjects who passed the spontaneously breathing trial (SBT) and did not need mechanical ventilation within 48 h were enrolled into a weaning success group. The subjects who did not pass the SBT or needed mechanical ventilation again within 48 h were enrolled into a weaning failure group. The risk factors associated with failure of weaning were studied by univariate and multivariate Logistic regression analysis.
ResultsThere were 53 subjects in the weaning success group and 23 in the weaning failure group. The incidences of sepsis, multiple organ dysfunction syndrome (MODS), fungal infection, hypoproteinemia, duration for mechanical ventilation > 14 d, the prevalences of aeropleura, cardiac failure, diabetes, coronary heart disease and hepatic insufficiency were higher in the weaning failure group than those in the weaning success group (P < 0.05). Logistic analysis revealed that MODS (OR=8.070), duration for mechanical ventilation > 14 d (OR=17.760), cardiac failure (OR=4.597) and diabetes (OR=13.937) were risk factors of weaning failure (P < 0.05).
ConclusionMODS, duration for mechanical ventilation > 14 d, cardiac failure and diabetes were associated with the failure of weaning from invasive mechanical ventilation in gerontal patients with AECOPD.
ObjectiveTo analyze the risk factors for post-thymectomy myasthenic crisis (PTMC) and prolonged mechanical ventilation, in myasthenia gravis patients who underwent extended thymectomy.
MethodsWe retrospectively analyzed the clinical data of 79 patients including 38 males and 41 females who experienced PTMC and required mechanical ventilation in Daping Hospital between June 2008 and November 2014. Single factor analysis and multivariate analysis were conducted.
ResultsMorbidity of PTMC was 20.6% (79/384). Result of single-factor analysis showed that postoperative pneumonia was one of the main reasons of prolonged mechanical ventilation (P < 0.05). Result of multiple-factor analysis showed that the operation time was positively correlated with mechanical ventilation time (P < 0.05). The risk factor of prolonged mechanical ventilation time in PTMC was not associated with sex, age, disease history, myasthenic crisis history, Osserman classification, dosage of pyridostigmine before and after the operation, surgical approach, bleeding volume, other therapies besides mechanical ventilation (P > 0.05).
ConclusionMechanical ventilation is one the main therapy of PTMC, operation time, and postoperative pneumonia are the main factors to prolong mechanical ventilation time. In order to decrease morbidity of PTMC and shorten mechanical ventilation time, the operation time should be controlled and pulmonary infection should be avoided.
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 study polyuria during mechanical ventilation in patients with chronic obstructive pulmonary disease ( COPD) and its possible mechanisms. Methods The plasma and urine concentrations of cystatin C ( CyC) were measured by enzyme immunometric assay in 26 COPD patients who received mechanical ventilation at timepoints of 0 h, 24 h, 48 h, 72 h and 1 week. And plasma levels of atrial natriuretic factor ( ANF ) , antidiuretic hormone ( ADH) and aldosterone ( ALD) were detected byradioimmunoassay at the same time-point. The urine volume was recorded every day. The samples of 30 healthy volunteers were measured as control. Results Polyuria phenomenon was found in majority of patients in 24 to 72 hours after mechanical ventilation. At 0h, the concentrations of plasma CyC, urine CyC,plasma ANF, ADH and ALD were all increased significantly compared with those of the control, respectively [ ( 4. 87 ±0. 51) mg/L vs ( 1. 29 ±0. 27) mg/L, ( 0. 58 ±0. 13) mg/L vs ( 0. 07 ±0. 02) mg/L, ( 37. 02 ±4. 35) pmol /L vs ( 22. 51 ±1. 18) pmol /L, ( 8. 61 ±1. 43) pmol /L vs ( 0.94 ±0. 34) pmol /L, ( 925. 4 ±142. 7) pmol /L vs ( 297. 5 ±135. 8) pmol /L, all P lt; 0. 01] , then decreased gradually after mechanical ventilation. The levels of plasma CyC and ANF at 24 h, plasma ADH at 72 h, and urine CyC at 1 week were similar to those of the control( all P gt;0. 05) , respectively, except the level of plasma ALD was still higher by 1 week( P lt; 0. 05) . Conclusions Polyuria is not a rare phenomenon for COPD patients receiving mechanical ventilation. Polyuria is related to the readjustment and mal-adaptation of ADH and reninangiotensin-aldosterone-systems during mechanical ventilation.
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.
Weaning difficulty is common in critically ill patients. Prolonged mechanical ventilation and weaning failure adversely affect the clinical outcome. How to better promote and achieve the early extubation is a very important subject. As a multi-dimensional monitoring method of important structure, function and morphology, critical care ultrasound which is helpful to improve our understanding and grasp of the core links in the respiratory circuit can comprehensively evaluate the state and reserve capacity of some important organs, such as the heart, lungs and diaphragm. It has great value in assessment of weaning and guided treatment. This paper will review the application of severe ultrasound in weaning.
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.
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.
