Venovenous extra-corporeal membrane oxygenation for severe acute respiratory distress syndrome: a matched cohort study / 中华医学杂志(英文版)

Background@#Although the use of extra-corporeal membrane oxygenation (ECMO) has been rapidly increasing, the benefit of ECMO in patients with acute respiratory distress syndrome (ARDS) remains unclear. Our objective was to investigate the effect of venovenous ECMO (VV-ECMO) on adult patients with severe ARDS.@*Methods@#We conducted a multi-center, retrospective, cohort study in the intensive care units (ICUs) of six teaching hospitals between January 2013 and December 2018. Patients with severe ARDS who received VV-ECMO support were included. The detailed demographic data and physiologic data were used to match ARDS patients without ECMO. The primary endpoint was the 28-day mortality.@*Results@#Ninety-nine patients with severe ARDS supported by VV-ECMO and 72 patients without ECMO were included in this study. The acute physiology and chronic health evaluation II score was 23.1 ± 6.3 in the ECMO group and 24.8 ± 8.5 in the control group (P = 0.1195). The sequential organ failure assessment score was 12.8 ± 3.4 in the ECMO group and 13.7 ± 3.5 in the control group (P = 0.0848). The 28-day mortality of patients with ECMO support was 39.4%, and that of the control group was 55.6%. The survival analysis curve showed that the 28-day mortality in the ECMO group was significantly lower than that in the control group (P = 0.0097). Multivariate Cox regression analysis showed that the independent predictors of the 28-day mortality were the requirement of vasopressors before ECMO (hazard ratio [HR]: 1.006; 95% confidence interval [CI]: 1.001–1.013; P = 0.030) and duration of mechanical ventilation before ECMO (HR: 3.299; 95% CI: 1.264–8.609; P = 0.034).@*Conclusions@#This study showed that ECMO improved the survival of patients with severe ARDS. The duration of mechanical ventilation and the requirement of vasopressors before ECMO might be associated with an increased risk of death.

Venovenous extra-corporeal membrane oxygenation for severe acute respiratory distress syndrome: a matched cohort study / 中华医学杂志(英文版)

BACKGROUND@#Although the use of extra-corporeal membrane oxygenation (ECMO) has been rapidly increasing, the benefit of ECMO in patients with acute respiratory distress syndrome (ARDS) remains unclear. Our objective was to investigate the effect of venovenous ECMO (VV-ECMO) on adult patients with severe ARDS.@*METHODS@#We conducted a multi-center, retrospective, cohort study in the intensive care units (ICUs) of six teaching hospitals between January 2013 and December 2018. Patients with severe ARDS who received VV-ECMO support were included. The detailed demographic data and physiologic data were used to match ARDS patients without ECMO. The primary endpoint was the 28-day mortality.@*RESULTS@#Ninety-nine patients with severe ARDS supported by VV-ECMO and 72 patients without ECMO were included in this study. The acute physiology and chronic health evaluation II score was 23.1 ± 6.3 in the ECMO group and 24.8 ± 8.5 in the control group (P = 0.1195). The sequential organ failure assessment score was 12.8 ± 3.4 in the ECMO group and 13.7 ± 3.5 in the control group (P = 0.0848). The 28-day mortality of patients with ECMO support was 39.4%, and that of the control group was 55.6%. The survival analysis curve showed that the 28-day mortality in the ECMO group was significantly lower than that in the control group (P = 0.0097). Multivariate Cox regression analysis showed that the independent predictors of the 28-day mortality were the requirement of vasopressors before ECMO (hazard ratio [HR]: 1.006; 95% confidence interval [CI]: 1.001-1.013; P = 0.030) and duration of mechanical ventilation before ECMO (HR: 3.299; 95% CI: 1.264-8.609; P = 0.034).@*CONCLUSIONS@#This study showed that ECMO improved the survival of patients with severe ARDS. The duration of mechanical ventilation and the requirement of vasopressors before ECMO might be associated with an increased risk of death.

Effects of Propofol on Respiratory Drive and Patient-ventilator Synchrony during Pressure Support Ventilation in Postoperative Patients: A Prospective Study / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Propofol is increasingly used during partial support mechanical ventilation such as pressure support ventilation (PSV) in postoperative patients. However, breathing pattern, respiratory drive, and patient-ventilator synchrony are affected by the sedative used and the sedation depth. The present study aimed to evaluate the physiologic effects of varying depths of propofol sedation on respiratory drive and patient-ventilator synchrony during PSV in postoperative patients.</p><p><b>METHODS</b>Eight postoperative patients receiving PSV for <24 h were enrolled. Propofol was administered to achieve and maintain a Ramsay score of 4, and the inspiratory pressure support was titrated to obtain a tidal volume (VT) of 6-8 ml/kg. Then, the propofol dose was reduced to achieve and maintain a Ramsay score of 3 and then 2. At each Ramsay level, the patient underwent 30-min trials of PSV. We measured the electrical activity of the diaphragm, flow, airway pressure, neuro-ventilatory efficiency (NVE), and patient-ventilator synchrony.</p><p><b>RESULTS</b>Increasing the depth of sedation reduced the peak and mean electrical activity of the diaphragm, which suggested a decrease in respiratory drive, while VT remained unchanged. The NVE increased with an increase in the depth of sedation. Minute ventilation and inspiratory duty cycle decreased with an increase in the depth of sedation, but this only achieved statistical significance between Ramsay 2 and both Ramsay 4 and 3 (P < 0.05). The ineffective triggering index increased with increasing sedation depth (9.5 ± 4.0%, 6.7 ± 2.0%, and 4.2 ± 2.1% for Ramsay 4, 3, and 2, respectively) and achieved statistical significance between each pair of depth of sedation (P < 0.05). The depth of sedation did not affect gas exchange.</p><p><b>CONCLUSIONS</b>Propofol inhibits respiratory drive and deteriorates patient-ventilator synchrony to the extent that varies with the depth of sedation. Propofol has less effect on breathing pattern and has no effect on VT and gas exchange in postoperative patients with PSV.</p>

Computer-driven automated weaning reduces weaning duration in difficult-to-wean patients / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Weaning difficulties occur in 31% of total intubated patients, and result in prolonged weaning duration. A computer-driven automated weaning system can perform a spontaneous breathing trial (SBT) automatically and display a message when the trial is successfully passed. Such a system might have a beneficial effect on difficult-to-wean patients. The aim of this study was to examine whether the computer-driven automated weaning system can accelerate discontinuation of mechanical ventilation and improve outcomes in difficult-to-wean patients.</p><p><b>METHODS</b>This randomized controlled study included 39 difficult-to-wean patients who failed their first spontaneous breathing trial. Before initiating weaning, eligible patients were randomly allocated to wean by computer-driven automated weaning system (CDW group, n = 19) or a physician-controlled local protocol (PW group, n = 20). Weaning duration, defined as the time from inclusion until first extubation, was the primary endpoint. Secondary endpoints were total duration of mechanical ventilation, the length of intensive care unit (ICU) stay, the number of reintubations, the mortality rate in the ICU, the number of noninvasive ventilations, the number of complications in the ICU, and the number of ventilator-associated pneumonia cases.</p><p><b>RESULTS</b>The weaning duration was reduced with the computer-driven weaning as compared with the usual protocol (median 29.0 hours vs. 45.5 hours, P = 0.044). Total duration of mechanical ventilation and duration of the ICU stay did not differ between the CDW and PW groups. There was no difference in the number of reintubations between the CDW and PW groups (3 and 4 patients, P = 0.732). The study groups showed comparable numbers of tracheostomy, self-extubations, ventilator-associated pneumonia, and non-invasive ventilation. Mortality in the ICU was similar in the CDW and the PW groups (21.1% vs. 20.0%, P = 0.935).</p><p><b>CONCLUSION</b>The computer-driven automated weaning system can reduce weaning duration in difficult-to-wean patients as compared with a physician-controlled weaning protocol.</p>

Positive end expiratory pressure titrated by transpulmonary pressure improved oxygenation and respiratory mechanics in acute respiratory distress syndrome patients with intra-abdominal hypertension / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Intra-abdominal hypertension (IAH) is common in acute respiratory distress syndrome (ARDS) patients and when resulting in decrease of chest wall compliance will weaken the effect of positive end expiratory pressure (PEEP). We investigated the effect of PEEP titrated by transpulmonary pressure (Ptp) on oxygenation and respiratory mechanics in ARDS patients with IAH compared with PEEP titrated by ARDSnet protocol.</p><p><b>METHODS</b>ARDS patients admitted to the intensive care unit (ICU) of the Zhongda Hospital were enrolled. Patients were ventilated with volume control mode with tidal volume of 6 ml/kg under two different PEEP levels titrated by Ptp method and ARDSnet protocol. Respiratory mechanics, gas exchange and haemodynamics were measured after 30 minutes of ventilation in each round. IAH was defined as intra-abdominal pressure of 12 mmHg or more.</p><p><b>RESULTS</b>Seven ARDS patients with IAH and 8 ARDS patients without IAH were enrolled. PEEP titrated by Ptp were significant higher than PEEP titrated by ARDSnet protocol in both ARDS patients with IAH ((17.3 ± 2.6) cmH2O vs. (6.3 ± 1.6) cmH2O and without IAH ((9.5 ± 2.1) cmH2O vs. (7.8 ± 1.9) cmH2O). Arterial pressure of O2/fraction of inspired oxygen (PaO2/FiO2) was much higher under PEEP titrated by Ptp when compared with PEEP titrated by ARDSnet protocol in ARDS patients with IAH ((27.2 ± 4.0) cmHg vs. (20.9 ± 5.0) cmHg. But no significant difference of PaO2/FiO2 between the two methods was found in ARDS patients without IAH. In ARDS patients with IAH, static compliance of lung and respiratory system were higher under PEEP titrated by Ptp than by ARDSnet protocol. In ARDS patients with IAH, central venous pressure (CVP) was higher during PEEP titrated by Ptp than by ARDSnet protocol.</p><p><b>CONCLUSION</b>Positive end expiratory pressure titrated by transpulmonary pressure was higher than PEEP titrated by ARDSnet protocol and improved oxygenation and respiratory mechanics in ARDS patients with IAH.</p>

Assessment of central venous-to-arterial CO(2) difference during early goal-directed therapy in patients with septic shock / 中华外科杂志

<p><b>OBJECTIVE</b>To detect the changes of central venous-to-arterial carbon dioxide difference (P(cv-a)CO(2)) during early goal-directed therapy (EGDT) in patients with septic shock and evaluate its' value in predicting adequate resuscitation and prognosis.</p><p><b>METHODS</b>From April 2009 to October 2010, 26 septic shock patients were enrolled in the study. EGDT was performed in all the patients immediately after enrollment. According to the whether they achieved early goal with in the 6 hour or not, patients were separated to EGDT achievement and un-achievement groups. At the onset and after the 6 hours EGDT, mean arterial pressure (MAP), cardiac index (CI), central venous oxygen saturation (ScvO(2)), oxygen delivery (DO(2)), oxygen consumption (VO(2)), oxygen extraction ratio (O(2) ext), lactate, P(cv-a)CO(2) were recorded. The Acute Physiology and Chronic Health Evaluation II (APACHE II) score and 28 day mortality were compared between 2 groups.</p><p><b>RESULTS</b>There were no significant difference of age and sex between the 15 patients who achieved early goals and 11 patients who did not. EGDT un-achievement patients had higher APACHE II score (21 ± 5) and 28 day mortality (9/11) when compared with EGDT achievement patients (t = 2.985, χ(2) = 4.547, P < 0.05). In EGDT un-achievement group, MAP, CI, DO(2), VO(2), O(2)ext, ScvO(2), Lac, P(cv-a)CO(2) were comparable between the onset and 6 hours after EGDT. However, in EGDT achievement group, MAP ((90 ± 9) mmHg (1 mmHg = 0.133 kPa)), CI ((4.0 ± 1.8) L×min(-1)×m(-2)), DO(2) ((596 ± 274) ml×min(-1)×m(-2)), ScvO(2) (76.9% ± 4.1%) increased, and P(cv-a)CO(2) ((4.2 ± 2.7) mmHg) decreased significantly after 6 hours of EGDT (t values were -3.393, -2.985, -2.103 and -3.195 respectively, all P < 0.05). The changes of P(cv-a)CO(2) between the onset and 6 hours after EGDT, demonstrated high value for predictability of outcome, according to the area under the ROC curve (AUC) was 0.839 (P = 0.004). As a predictor for death, increasing of P(cv-a)CO(2) after 6 hours of EGDT has a sensibility of 100% and specificity of 60%.</p><p><b>CONCLUSIONS</b>Increasing of P(cv-a)CO(2) after EGDT purports inadequate tissue perfusion in patients with septic shock. Changes of P(cv-a)CO(2) during EGDT demonstrated a useful tool to evaluate adequate resuscitation and prognosis.</p>

Effects of different reference point on intra-abdominal pressure measurement in critically ill patients: a clinical trial / 中华外科杂志

<p><b>OBJECTIVE</b>To investigate the effects of different reference point on intra-abdominal pressure (IAP) measurement.</p><p><b>METHODS</b>Nine critically ill patients with risk of intra-abdominal hypertension (IAH) were studied from July 2008 to June 2010, all of the patients were equipped with abdominal cavity drain and urinary drainage tube. By which IAP was measured using direct and indirect methods respectively. The symphysis pubis, phlebostatic axis and the midaxillary line at the level of the iliac crest were defined as reference points. According to the different reference point, three sets of IAP measurements were obtained in the supine position with each method and kept as IAP(S), IAP(P), IAP(I). Bland-Altman method analysis and Pearson's correlation were performed to evaluate the relationships between results from different reference points with direct and indirect methods. Paired t-test was performed to evaluate the differences among different reference points.</p><p><b>RESULTS</b>Sixty measurements of IAP(S), IAP(P) and IAP(I) were obtained. In direct measurement through abdominal cavity drain, IAP(I) (13.8 ± 3.9) mmHg (1 mmHg = 0.133 kPa) was significantly higher than IAP(P) (12.8 ± 3.6) mmHg and IAP(S) (9.1 ± 3.6) mmHg, P < 0.05; while in indirect measurement through urinary drainage tube, IAP(I) (12.7 ± 3.2) mmHg was significantly higher than IAP(P) (11.7 ± 2.9) mmHg and IAP(S) (7.9 ± 3.0) mmHg too, P < 0.05. In either direct or indirect method, IAP(P) was higher than IAP(S), P < 0.05. And good correlations were found among IAP(S), IAP(P) and IAP(I).</p><p><b>CONCLUSIONS</b>In the supine position, pressure obtained via the bladder could reflect authentic IAP. But selection of reference point has great impact on IAP measurement.</p>

Prospective research on the prognosis of septic shock based on the change of lactate concentration in arterial blood / 中华外科杂志

<p><b>OBJECTIVE</b>To evaluate the correlation between the lactate in artery blood and lactate clearance rate and prognosis in patients with septic shock in intensive care unit (ICU).</p><p><b>METHODS</b>Prospectively studied 221 consecutive patients with septic shock from December 2005 to December 2007, the diagnosis of septic shock was made based on the criteria of 2001 ACCP/SCCM. For inclusion in the study, we required admission of the patients within 24 h of septic shock diagnosed. The criteria for exclusion from the study were an age of less than 18 years, pregnancy, serious inadequacy of liver and renal, needing blood purification, or acidosis result of biguanides drugs, or do-not-resuscitate. The eligible patients assigned to early goal-directed therapy. The 6-, 24- and 72-hour lactate clearance rate were calculated, the relationship between the level of lactate, lactate clearance rate, the APACHE II score, the number of failed organ and the 28-day mortality were evaluated.</p><p><b>RESULTS</b>One hundred and five patients with septic shock were admitted, 74 male and 31 female, the mean age was 70 +/- 12 years. The 28-day mortality was 54.3%. The average APACHE II score at baseline was 20 +/- 8, the number of failed organs was 3.0 +/- 1.1 and the average concentration of lactate in artery blood at baseline was (3.8 +/- 3.6) mmol/L. Significant differences of the lactate at 0-, 6-, 24- and 72-hour were found between death group and survival group. There were 69 patients whose lactate in artery blood at baseline was > 2 mmol/L, 24 survived. The lactate clearance rate of 6- and 24-hour in survival group were significantly higher than death group (P < 0.01, P < 0.05, respectively), but the lactate clearance rate of 72-hour was not (P > 0.05). By using a multivariate logistic regression analysis, it showed that the lactate clearance rate of 6-hour was the independent predictive factor of survival. The area under the receiver operating characteristic curve (ROC) was 0.564, 0.649, 0.754, 0.784, respectively according to the level of the lactate at 0-, 6-, 24-hour and the 6-hour lactate clearance rate. The cutoff of 6-hour lactate clearance rate was >or= 30.0%, resulting in a sensitivity of 60.0% and a specificity of 77.3%.</p><p><b>CONCLUSIONS</b>Dynamic observation of lactate level is very important for the survival in the patients with septic shock. Patients with elevated lactate and not decreased rapidly have a worse outcome. The 6-hour lactate clearance rate might be the indicator for predicting the prognosis of patients with septic shock.</p>

Assessment of stroke volume variation and intrathoracic blood volume index on the responsiveness to volume loading in mechanically ventilated canine with hemorrhagic shock / 中华外科杂志

<p><b>OBJECTIVE</b>To assess the significance of stroke volume variation (SVV) and intrathoracic blood volume index (ITBI) on the responsiveness to volume loading in mechanically ventilated canine with hemorrhagic shock.</p><p><b>METHODS</b>Hemorrhagic shock canine model was established with the modified Wiggers' method. The heart rate (HR), mean artery pressure (MAP), central venous pressure (CVP), pulmonary artery wedge pressure (PAWP), intrathoracic blood volume index (ITBI) and stroke volume variation (SVV) were investigated by Swan-Ganz catheter or PiCCO monitor. Graded volume loading (VL) was performed. Successive responsive VLs were performed (increase in SV > 5% after VL) until continuous change in SV < 5% (unresponsive) was reached.</p><p><b>RESULTS</b>Fourteen canines were studied and a total of 134 VLs were performed. In 94 VLs, an increase in SV of more than 5% was reached. In the other 40 VLs, increase in SV was less than 5%. The change of HR, MAP, ITBI, SVV in responsive were more than those of unresponsive after VL. The change of CVP, PAWP in responsive were less than those of unresponsive. Significant correlation was found between DeltaSV after VL and the baseline values of ITBI, SVV. No correlation was found between DeltaSV and HR, MAP, CVP, PAWP. Significant correlations were also found between DeltaSV and DeltaCVP, DeltaPAWP, DeltaITBI, DeltaSVV after fluid loading. No correlation was found between DeltaSV and DeltaHR, DeltaMAP. By using receiver operating characteristic analysis, the area under the curve were 0.872 for SVV and 0.689 for ITBI, more than those of HR, MAP, CVP, PAWP statistically. As SVV value of 9.5% or more will predict an increase in the SV of at least 5% in response to a VL with a sensitivity of 92.6% and a specificity of 82.5%.</p><p><b>CONCLUSIONS</b>SVV and ITBI were more useful indicators than CVP and PAWP on the assessment of responsiveness to volume loading. SVV as a functional preload parameter and for on-line monitoring may help to improve the hemodynamic management.</p>