Correlation between dead space fraction and pulmonary ultrasound score in patients with acute respiratory distress syndrome and its prognostic value / 中华危重病急救医学

Objective:To investigate the correlation between dead space fraction and lung ultrasound score (LUS) and their prognostic value in patients with acute respiratory distress syndrome (ARDS).Methods:The data of 98 patients with ARDS treated in the intensive care unit (ICU) of the First Affiliated Hospital of Jinzhou Medical University from January to December 2020 were collected and analyzed. The gender, age, acute physiology and chronic health evaluationⅡ(APACHEⅡ), oxygenation index, dead space fraction and LUS score immediately and 24, 48, 72 and 96 hours after ICU admission and 28-day outcomes of all patients were collected. Pearson correlation was used to analyze the correlation between dead space fraction and LUS score. Binary Logistic regression was performed to analyze whether the dead space fraction and LUS score could be the risk factors of the prognosis in patients with ARDS. Receiver operator characteristic curve (ROC) was used to analyze the predictive effect of dead space fraction and LUS score on 28-day mortality in patients with ARDS.Results:A total of 98 patients with ARDS were included, of which 76 cases survived and 22 cases died within 28 days. With the prolongation of ICU stay, the dead space fraction and LUS score in the survival group increased first and then decreased. The dead space fraction and LUS score in the death group continued to increase to 96 hours, and were significantly higher than those in the survival group (dead space fraction: 0.569±0.019 vs. 0.491±0.021, LUS score: 20.09±2.39 vs. 15.13±1.91, both P < 0.05). There was a positive correlation between the dead space fraction and LUS score at 48, 72 and 96 hours in ICU ( r values were 0.200, 0.471 and 0.677, all P < 0.05). Binary Logistic regression analysis showed that dead space fraction and LUS score were independent risk factors affecting the prognosis of patients with ARDS [dead space fraction: odds ratio ( OR) was 69.064, 95% confidence interval (95% CI) was 22.680-123.499, P = 0.008; LUS score: OR was 4.790, 95% CI was 1.609-14.261, P = 0.005]. The results of ROC curve analysis showed that the dead space fraction at 48, 72 and 96 hours after ICU admission could be used to predict the 28-day mortality of patients with ARDS, the sensitivity was 59.1%, 90.9% and 95.5%, and the specificity was 89.5%, 80.3% and 98.7%. The area under the curve (AUC) of dead space fraction predicting 28-day mortality was 0.802, 0.952 and 0.998, all P < 0.01. The LUS score of 72 hours and 96 hours in ICU could be used to predict the 28-day mortality of patients with ARDS, the sensitivity was 77.3%, 77.3% and 100.0%, and the specificity was 68.4%, 88.2% and 80.3%, respectively. The AUC of the LUS score to predict the 28-day mortality of patients were 0.935 and 0.959, both P < 0.01. Conclusion:There was significant correlation between dead space fraction and LUS score, both of which were risk factors of 28-day mortality and be used to evaluate the 28-day prognosis of patients with ARDS.

Dead space fraction for treatment guidance and prognosis evaluation of acute respiratory distress syndrome / 中华危重病急救医学

Acute respiratory distress syndrome (ARDS) is a common cause of critical illness and high mortality from respiratory failure. Increased dead space fraction (VD/VT) was independently associated with lung injury and mortality of ARDS. VD/VT is readily obtained by bedside measurements of arterial blood gas and end-tidal carbon dioxide. Early attention and application of VD/VT as an indicator will help to better understand the pathophysiological of ARDS, guide clinical treatment, and better assess the severity and clinical prognosis of the disease.

Study on severity and outcome in children with acute respiratory distress syndrome by measurement of alveolar dead space fraction / 中国小儿急救医学

Objective To investigate the role of alveolar dead space fraction(ADSF) on the severity and outcome among children with acute respiratory distress syndrome ( ARDS). Methods Totally 20 chil-dren with ARDS in early stage were enrolled in this prospective study from December 2016 to November 2017 in PICU of Shengjing Hospital of China Medical University. According to the OI value,the cases were devided into mild-moderate group(4≤OI <16,n ＝12)and severe group (OI≥16,n ＝8). According to 28-day hospital mortality,the cases were devided into survival group(n＝11) and death group (n＝9). The general situation,PaCO2,PetCO2,oxygenation index(P/F,O/I) and 28-day hospital mortality were recorded and evaluated,and ADSF was measured by ADSF＝( PaCO2-PetCO2)/PaCO2. These variables were ana-lyzed by using student′s t-test,non-parametric test and ROC curve,to analyze the relationship between the severity of ARDS and ADSF,and the predictive value of the prognosis. Results (1) Compared with the mild-moderate group,the OI and ADSF of the severe group were significantly higher,and the P/F was signif-icantly lower(P<0. 05). (2)Compared with the survival group,the OI and ADSF of the death group were significantly higher,and the P/F was significantly lower(P<0. 05). (3)The area under the ROC judged by ADSF was 0. 690 (P<0. 05). If 0. 338 was as the critical value to evaluate the prognosis,the sensitivity and specificity for judging death were 0. 704 and 0. 634,respectively. The AUC of predicting the prognosis with OI was 0. 720 (P<0. 05). If 0. 348 was as the critical value to predict death,the sensitivity and specificity were 0.551 and 0.797,respectively. The area under the ROC judged by P/F was 0.256(P > 0.05). Conclusion The ADSF on early stage is higher in children with severe ARDS than those with mild to moderate ARDS. The ADSF on early stage is higher in death group than that in survival group. ADSF is of guiding significance in the prognosis of ARDS.

Application of alveolar dead space fraction in acute respiratory distress syndrome / 国际儿科学杂志

The high mortality of acute respiratory distress syndrome(ARDS) has been a great challenge in the intensive care unit and early diagnosis and treatment have greatly improved the prognosis of ARDS.In the previous studies,the problem has been studied mainly on the alveolar collapse and pulmonary shunt.However,recent studies have shown that the alveolar dead space ventilation in ARDS is also significantly increased,and may be related to the severity and prognosis of ARDS which has received a generous concern and become a research focus.This article reviews the progress in alveolar dead space fraction (ADSF) which may shed light on the role of ADSF in the diagnosis and treatment of ARDS.

Evaluation value of dead-space fraction on prognosis of acute respiratory distress syndrome / 重庆医学

Objective To investigate the dynamic changes of dead space fraction (VD/VT) and its effect on the prognosis in the patients with acute respiratory distress syndrome (ARDS).Methods Thirtytwo patients with ARDS in EICU of the First Affiliated Hospital of Kunming Medical University from January 2015 to August 2016 were selected and divided into the survival group and the death group according to the 28 d mortality rate.VD/VT on 1-6 d in the two groups was calculated according to the formula.The parameters of basic condition,PaO2/FiO2,APACHE Ⅱ score,LIPS score,PEEP of the two groups were compared.Results LIPS and APACHE Ⅱ scores had statistical difference between the death group and survival group (P＜0.05);VD/VT on 1-3 d had no statistical difference between the two groups (P＞0.05),and VD/VT on 4-6 d in the death group was significantly higher than that in the survival group (P＜0.01).△PCO2,pH and PaO2/FiO2 had statistical difference between the death group and the survival group (P＜0.05).The binary classification Logistic regression analysis found that APACHE Ⅱ,LIPS,△PCO2,VD/VT were the risk factors.VD/VT on the 4th day was selected,its' cut off value was 0.62,and the sensitivity of the prognostic evaluation was 90.0 ％,the specificity was 95.5 ％.Conclusion The dead space fraction is an independent risk factor for the prognosis of ARDS patients,and VD/VT on 4th day could effectively identify the high-risk patients.

Prognostic value of the pulmonary dead-space fraction in patients during the early phases of acute respiratory distress syndrome / 中华急诊医学杂志

ObjectiveTo evaluate the association between alveolar dead space fraction and the prognosis of patients with acute respiratory syndrome in the early phase ( ＜ 3 days).MethodsTwentythree patients with ARDS were enrolled in this study.The VD/VT was measured by the single breath test of CO2 (SBT-CO2).The age,heart rate,mean arterial pressure,APACHE Ⅱ,Murray lung injury score,functional residual capacity ( FRC ),PaO2/FiO2,tidal volume,airway plateau pressure ( Pplat ),static pulmonary compliance (Cst),28-day mortality were recorded.ResultsThe alveolar dead-space fraction was markedly elevated (0.59 ±0.06) and the mean FRC was markedly decreased (1643 ±409) ml in the early phase of ARDS.The mortality of 28 days was 52.2％.The mean dead-space fraction was significantly higher in non-survived patients than that in survival [(0.64 ± 0.08 ) vs.(0.53 ±0.04 )].VD/VT was correlated significantly with Murray lung injury score ( r=0.464,P =0.026).The area under the ROC curve for dead space fraction was 0.867,with sensitivity of 83％,and specificity of 82％.Conclusions Increased alveolar dead-space fraction of patients in the early phases of ARDS is associated with greater risk of death.

Dead space guided positive end-expiratory pressure in patients with acute respiratory distress syndrome / 中华内科杂志

ObjectiveTo evaluate the value of dead space fraction (VD/VT) guided positive end expiratory pressure ( PEEP ) in acute respiratory distress syndrome ( ARDS ).Methods Twenty-three intubated and mechanically ventilated patients with early ARDS were enrolled in the study.PEEP was titrated by lowest VD/VT.Parameters of oxygenation and respiratory mechanics were observed.Results PEEP titrated by lowest VD/VT and highest static lung compliance ( CLst ) ( P ＞ 0.05 ) respectively,were lower than PEEP titrated by optimal oxygenation ( P ＜ 0.05),but there was no significant difference between lowest VD/VT and highest Ctst method.The VD/VT that ventilated on PEEP titrated by the lowest VD/VT decreased than its basal level.There was no difference significantly between the VD/VT that ventilated on PEEP elected by the other two methods with basal level ( P ＞ 0.05 ).The the ratio of arterial PO2 to the inspired oxygen fraction (PaO2/FiO2)ratios improved significantly than the baseline values in three ventilation strategies,and that ventilated on PEEP targeting the lowest VD/VT was lower than PEEP targeting optimal oxygenation.The plateau airway pressure that ventilated on PEEP targeting optimal oxygenation was higher than the other two methods.The functional residual capacity (FRC) of patients ventilated by PEEP targeting optimal oxygenation was increased than the lowest VD/VT and maximum CLst.Conclusions VD/VT could be one of the methods to titrate the optimal PEEP in patients with early ARDS.Optimal PEEP targeting the highest compliance in conjunction with the lowest dead space fraction indicated a maximumamount of effectively expanded alveoli.