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Mechanical ventilation is an importmant life-sustaining treatment for patients with acute respiratory distress syndrome. Its clinical outcomes depend on patients' characteristics of lung recruitment. Estimation of lung recruitment characteristics is valuable for the determination of ventilatory maneurvers and ventilator parameters. There is no easily-used, bedside method to assess lung recruitment characteristics. The present paper proposed a method to estimate lung recruitment characteristics from the static pressure-volume curve of lungs. The method was evaluated by comparing with published experimental data. Results of lung recruitment derived from the presented method were in high agreement with the published data, suggesting that the proposed method is capable to estimate lung recruitment characteristics. Since some advanced ventilators are capable to measure the static pressure-volume curve automatedly, the presented method is potential to be used at bedside, and it is helpful for clinicians to individualize ventilatory manuevers and the correpsonding ventilator parameters.
Subject(s)
Humans , Lung , Positive-Pressure Respiration , Respiration, Artificial , Respiratory Distress Syndrome, Newborn , Ventilators, MechanicalABSTRACT
Objective@#To investigate the effect of mechanical ventilation in prone position combined with lung recruitment on severe acute respiratory distress syndrome (ARDS).@*Methods@#From February 2015 to February 2017, 82 patients with ARDS admitted to ICU of the Second Hospital of Shanxi Medical University were divided into two groups according to random number table, with 41 cases in each group.The study group was treated with mechanical ventilation in prone position combined with lung recruitment therapy, and the control group was treated with mechanical ventilation in supine position combined with lung recruitment therapy.The differences of heart rate (HR), central venous pressure (CVP), mean arterial pressure (MAP), partial pressure of oxygen (PaO2), oxygenation index (PaO2/FiO2), plateau pressure (Pplat), and static pulmonary compliance (Cst) were compared between the two groups before treatment (T0), and 1h (T1), 2h (T2), 6h (T3) after treatment.@*Results@#The PaO2 and PaO2/FiO2 levels of the two groups increased significantly after lung recruitment.In the study group at different time after treatment, PaO2[(69.17±7.51)mmHg, (74.64±6.78)mmHg, (82.52±10.37)mmHg], PaO2/FiO2 [(116.91±15.57)mmHg, (123.06±16.34)mmHg, (135.23±18.41)mmHg]were higher than those in the control group[PaO2: (64.23±7.72)mmHg, (68.51±8.05)mmHg, (73.43±9.12)mmHg; PaO2/FiO2: (106.50±12.97)mmHg, (115.42±13.19)mmHg, (123.42±14.95)mmHg], the differences were statistically significant (t=3.225, 3.254, 4.245, 3.954, 3.886, 4.135, all P<0.05). HR and CVP increased at T2-T3, T3 decreased, MAP decreased at T2-T3, and T3 increased in both two groups.HR at T1-T3 in the study group were (123.17±13.41)times/min, (114.64±10.08)times/min, (102.52±6.57)times/min, which were lower than those in the control group[(129.23±12.75)times/min, (117.51±10.35)times/min, (108.43±9.77)times/min], the differences between the two groups were statistically significant (t=3.884, 4.215, 4.667, all P<0.05).@*Conclusion@#Prone position mechanical ventilation combined with lung recruitment can effectively improve the oxygenation status of severe ARDS, and has less effect on hemodynamics, and the effect is better than supine position mechanical ventilation combined with lung recruitment.
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Objective To investigate the effect of mechanical ventilation in prone position combined with lung recruitment on severe acute respiratory distress syndrome (ARDS).Methods From February 2015 to February 2017,82 patients with ARDS admitted to ICU of the Second Hospital of Shanxi Medical University were divided into two groups according to random number table,with 41 cases in each group.The study group was treated with mechanical ventilation in prone position combined with lung recruitment therapy,and the control group was treated with mechanical ventilation in supine position combined with lung recruitment therapy.The differences of heart rate (HR),central venous pressure (CVP),mean arterial pressure (MAP),partial pressure of oxygen (PaO2),oxygenation index (PaO2/FiO2),plateau pressure (Pplat),and static pulmonary compliance (Cst) were compared between the two groups before treatment (T0),and 1h (T1),2h (T2),6h (T3) after treatment.Results The PaO2 and PaO2/FiO2 levels of the two groups increased significantly after lung recruitment.In the study group at different time after treatment,PaO2 [(69.17 ±7.51) mmHg,(74.64 ±6.78) mmHg,(82.52 ± 10.37) mmHg],PaO2/FiO2 [(116.91 ±15.57) mmHg,(123.06 ± 16.34) mmHg,(135.23 ± 18.41) mmHg] were higher than those in the control group [PaO2:(64.23 ± 7.72) mmHg,(68.51 ± 8.05) mmHg,(73.43 ± 9.12) mmHg;PaO2/FiO2:(106.50 ± 12.97) mmHg,(115.42 ± 13.19) mmHg,(123.42 ± 14.95) mmHg],the differences were statistically significant (t =3.225,3.254,4.245,3.954,3.886,4.135,all P ＜ 0.05).HR and CVP increased at T2-T3,T3 decreased,MAP decreased at T2-T3,and T3 increased in both two groups.HR at T1-T3 in the study group were (123.17 ± 13.41) times/min,(114.64 ± 10.08) times/min,(102.52 ± 6.57) times/min,which were lower than those in the control group [(129.23 ±12.75) times/min,(117.51 ± 10.35) times/min,(108.43 ± 9.77) times/min],the differences between the two groups were statistically significant (t =3.884,4.215,4.667,all P ＜ 0.05).Conclusion Prone position mechanical ventilation combined with lung recruitment can effectively improve the oxygenation status of severe ARDS,and has less effect on hemodynamics,and the effect is better than supine position mechanical ventilation combined with lung recruitment.
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The main pathophysiological features of acute respiratory distress syndrome (ARDS) are alveolitis edema,collapse and V/Q ratio imbalance. Consensus Recommendations from the Pediatric Acute Lung Injury Consensus Conference recommends that the lung protective ventilation strategy be the first choice for mechanical ventilation of PARDS with small tidal volume and high positive end-expiratory pressure (PEEP) used to improve oxygenation. High PEEP is an important technical tool for the " Open Lung Con-cept". It is beneficial to improve oxygenation through the operation of lung recruitment (RM) and the main-tenance of alveolar open. High PEEP reduced the formation of pulmonary edema in animal experimental mod-els. Large-scale adult randomized controlled trials have shown that high PEEP may reduce mortality in patients with severe hypoxemia,but it is currently subject to some challenges. Simultaneously,high PEEP and ventilator-induced lung injury(VILI) caused by excessive lung expansion are closely related,and increase the incidence of barotrauma and pneumothorax. High PEEP may reduce the volume of blood returning to the heart,reduce cardiac output,and also reduce cerebral perfusion pressure and aggravate brain edema. It is still a highly controversial issue to use high PEEP to optimize lung recruitment in patients with ARDS and to choose the best PEEP to maintain the alveolar open. It has been suggested that the purpose of lung recruitment is no longer to restore normal lung ventilation,but to provide reasonable arterial oxygen saturation and reduce oxy-gen toxicity priority. PEEP above 10 cmH2 O is suggested to be used to optimize lung recruitment if lung col-lapse is diffuse. When the lung collapse is locally distributed,it is not suitable to use excessive PEEP for RM and other methods can be used to improve V/Q ratio.
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Objective Vibration response imaging (VRI) has been applied to the bedside monitoring of critically ill patients. The purpose of this study was to explore the value of VRI in assessing lung recruitment in patients with acute respiratory distress syndrome (ARDS). Methods We prospectively studied the clinical data on 20 cases of ARDS treated in our Department of Pulmonary and Critical Care Medicine from January 2015 to June 2017. The positive end-expiratory pressure (PEEP) of the patients was increased from 5 and 15 cm H2O, the mean grey value of the max energy frame of VRI was determined, the quantitative lung data (QLD) were obtained, and the correlation of the VRI image with the recruited lung volume and oxygenation index was analyzed. Results The patients with PEEP at 15 cm H2O, in comparison with those with PEEP at 5 cm H2O, showed a significantly decreased mean gray value of the max energy frame of VRI (169.1 ± 11.3 vs 175.1 ± 15.9, P = 0.04), increased gray area ([56.3 ± 4.4]% vs [52.7 ± 7.5]%, P < 0.05), declined QLD in the upper left and left middle regions (P < 0.05) and elevated in the lower left and lower right regions (P < 0.05). With the PEEP at 15 cm H2O, the mean gray value of VRI was increased by -5.6 ± 12.8, negatively correlated with the recruited lung volume (r = -0.785, P < 0.01), and the gray area increased (3.8 ± 4.8)%, positively correlated with the recruited lung volume (r =0.793, P < 0.01). With PEEP at 5 and 15 cm H2O, the oxygenation indexes were (116.3 ± 25.6) mmHg and (116.3 ± 25.6) mmHg, respectively, the improvement rate of which correlated negatively with the increased mean gray value of VRI (r = -0.740, P < 0.01) but positively with the gray area (r = 0.581, P < 0.01). Conclusion Lung recruitment can be adequately estimated with bedside VRI in patients with ARDS.
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Objective To investigate the effect of lung recruitment maneuver on alveolar collapse after fiber support bronchoscopy,and to evaluate its clinical value.Methods Since April 2014 and April 2017 in underwent deep hypothermia and stop of 60 cases of hypoxemia in patients with postoperative aortic circulation as the research object,according to the random number distribution method.The average score of the two groups,each group with 30 cases in each.The control group was treated with conventional fiber bronchoscopy and end expiratory positive pressure ventilation in the treatment,observation group patients on the basis of the application of lung recruitment method to carry on the treatment.Observation compared two groups of patients with lung recruitment maneuver and respiration and circulation of the parameter variations and mechanical ventilation in time.Results Two groups of patients with treatment of the parameters,the difference was not statistically significant (P ＞0.05);after treatment,observation group of patients with oxygen synthetic index and mechanical ventilation time and the control group was significant difference compared with statistical significance(P ＜ 0.05);and two groups of patients with arterial carbon dioxide into change of pressure and tidal volume before and after the treatment were not significant,no statistical significance(P ＞ 0.05).Two groups of patients with the circulatory system index tends to be stable,no significant change (P ＞0.05).Conclusion The use of bronchoscopy in patients with aortic dissection after the examination of hypoxia,application of lung recruitment maneuver method for treatment,can improve the patient's oxygenation index,reduce the time of mechanical ventilation in patients with.
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Objective • To find out the optimal positive end expiratory pressure (PEEP) by electrical impedance tomography (EIT) for better lung recruitment and ventilation distribution in patients undergoing off pump coronary artery bypass grafting surgery (OPCAB). Methods • 105 patients underwent OPCAB from Jan. 2017 to Dec. 2017 were analysed. Patients were randomly divided into two groups, i.e. experiment group (54 cases) and control group (51 cases). Four regions of interest (ROI) were recorded by EIT. PEEP were 3 cmH2O in control group while PEEP were increased stepwise by 2 cmH2O from 0 cmH2O to 14 cmH2O in experiment group. The optimal PEEP for lung recruitment was applied in experiment group. Postoperative oxygenation index (PaO2/FiO2) and pulmonary complication were compared between two groups. Results • The overall mortality was 2 (1.90%). The incidence of postoperative pulmonary complication, pulmonary infection, atelectasis, pleural effusion were 18.10%, 2.86%, 18.10%, 18.10%, respectively. The optimal PEEP zone was 6-9 cmH2O. PaO2/FiO2 was significantly increased with the optimal PEEP in experiment group (P=0.00). There were significant differences in postoperative pulmonary complication between two groups (P=0.02). Conclusion • EIT can directly monitor ventilation distribution and titrate suitable PEEP for better lung recruitment in patients undergoing OPCAB. It can significantly reduce postoperative pulmonary complication, improve oxygenation, and decrease ICU stay and ventilation duration.
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Objective·To find out the optimal positive end expiratory pressure (PEEP) by electrical impedance tomography (EIT) for better lung recruitment and ventilation distribution in patients undergoing off pump coronary artery bypass grafting surgery (OPCAB). Methods?·?105 patients underwent OPCAB from Jan. 2017 to Dec. 2017 were analysed. Patients were randomly divided into two groups, i.e. experiment group (54 cases) and control group (51 cases). Four regions of interest (ROI) were recorded by EIT. PEEP were 3?cmH2O in control group while PEEP were increased stepwise by 2?cmH2O from 0?cmH2O to 14?cmH2O in experiment group. The optimal PEEP for lung recruitment was applied in experiment group. Postoperative oxygenation index (PaO2/FiO2) and pulmonary complication were compared between two groups. Results?·?The overall mortality was 2 (1.90%). The incidence of postoperative pulmonary complication, pulmonary infection, atelectasis, pleural effusion were 18.10%, 2.86%, 18.10%, 18.10%, respectively. The optimal PEEP zone was 6-9?cmH2O. PaO2/FiO2was significantly increased with the optimal PEEP in experiment group (P=0.00). There were significant differences in postoperative pulmonary complication between two groups (P=0.02). Conclusion?·?EIT can directly monitor ventilation distribution and titrate suitable PEEP for better lung recruitment in patients undergoing OPCAB. It can significantly reduce postoperative pulmonary complication, improve oxygenation, and decrease ICU stay and ventilation duration.
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Objective To evaluate the effect of active cycle of breathing techniques(ACBT) on promoting lung recruitment in post-thoracic surgery patients with lung cancer. Methods Totally 100 cases of patients with lung cancer were collected and randomly divided into two groups(the control group and the observation group) with 50 cases in each group. The additional ACBT was applied≥3 times per day in the control group compared with the observation group. The main observation indexes(pulmonary function and arterial blood gas, etc) and the secondary indexes(vital signs and pain score, etc) of the patients were collected at different time period. Results The main observation index and the secondary index of the patients in the control group gained an advantage over those in the observation group(P＜0.05). No obvious adverse events occurred. Conclusion ACBT applied in the post-thoracic surgery patients with lung cancer is safe and effective. It can improve the cleaning efficiency of respiratory secretion, promote lung recruitment and fastly recover the pulmonary function and save medical costs.
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Objective To explore the clinical effect of ulinastatin combined with recruitment maneuver on extrapulmonary acute respiratory distress syndrome (ARDS). Methods Forty-two patients with extrapulmonary ARDS, who received ulinastatin combined with recruitment maneuver in Eastern Hepatobiliary Surgery Hospital of Second Military Medical University from Jun. 2014 to Jun. 2016, were assigned to experimental group; and 45 patients with extrapulmonary ARDS, who were treated by recruitment maneuver without ulinastatin at the same time, were taken as control group. The blood gas analyzer was used to record radial arterial oxygen partial pressure (PaCO2), carbon dioxide partial pressure (PaCO2) and oxygenation index (OI) before and after treatment in the two groups; the breathing machine was used to record the inspiratory peak pressure (PIP), plateau pressure (Pplat), static lung compliance (Cs) and dynamic lung compliance (Cd); and ELISA was used to detect the serum levels of IL-6, TNF-α and IL-10. Results PaCO2 on 2nd, 3rd, 5th, 6th and 7th day after treatment, PaCO2 on 1st, 3rd, 5th and 7th day after treatment, and OI on 6th and 7th day after treatment in the experimental group were higher than those in the control group (all P<0.05). After treatment, PIP and Pplat in the two groups were significantly decreased (P<0.05), and Cs and Cd were significantly increased (P<0.05); the changes in the experimental group were significantly greater compared with the control group (P<0.05). In the experimental group and the control group, IL-6 and TNF-α levels were significantly decreased (P<0.05), and IL-10 levels were increased (P<0.05) after treatment; the changes in the experimental group were significantly greater compared with the control group (P<0.05). Conclusion Ulinastatin combined with recruitment maneuver can more effectively reduce lung injury and improve pulmonary ventilation of the patients with extrapulmonary ARDS compared with simple recruitment maneuver.
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Objective To discuss the effects of pressure control (PC) and positive end-expiratory pressure (PEEP) incremental method lung recruitment maneuver (RM) on haemodynamics in piglets with acute lung injury (ALI) induced by paraquat (PQ) poisoning. Methods The ALI/acute respiratory distress syndrome (ARDS) model was reproduced by intraperitoneal injection of 20% PQ (20 mL) in 10 healthy female piglets, and they were randomly divided into PC lung RM group (RM1 group) and PEEP incremental method lung RM group (RM2 group), with 5 piglets in each group. Heart rate (HR), mean arterial pressure (MAP), and cardiac index (CI) were monitored by pulse-indicated continuous cardiac output (PiCCO) monitoring before model reproduction (baseline), on the time of successfully set up of model and at 5, 15 and 30 minutes after RM. At the same time the arterial partial pressure of oxygen (PaO2) and arterial partial pressure of carbon dioxide (PaCO2) were recorded, and oxygenation index was calculated. Lung tissues were collected before model reproduction, on the time of successfully set up of model, and at 30 minutes after RM respectively, and pulmonary pathology changes were observed after hematoxylin and eosin (HE) staining under light microscopy. Results The HR, MAP, and PaCO2 on the time of successfully set up of model in both groups were increased obviously while CI, PaO2, and oxygenation index were decreased obviously as compared with those at baseline, all of which conformed to the expression of ALI/ARDS. With RM time extended, the HR in both groups was declined while MAP and CI were increased gradually. The HR and MAP at 5 minutes after RM of RM1 group were significantly lower than those of the RM2 group [HR (bpm): 126.8±5.2 vs. 134.0±3.8, MAP (mmHg, 1 mmHg = 0.133 kPa): 98.4±3.3 vs. 102.8±2.6, both P 0.05). The lung tissue in both groups showed a variety of pathological changes at 30 minutes after RM. The main performances were the loss of alveolar epithelial cells, the further wideness of alveolar interval and the distension of alveolar, and the part breakage of alveolar interval. The wideness of alveolar interval was more significant in RM2 group than that of RM1 group, and alveolar cleft was more common too. Conclusion Both PC and PEEP incremental method lung RM can improve the oxygenation of the piglets with ALI/ARDS induced by PQ, and the PC lung RM has less impact on haemodynamics.
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ObjectiveTo investigate the effect of different degrees of pressure of sustained inflation (SI) in patients with acute respiratory distress syndrome (ARDS) after lung recruitment as the result of different negative pressure for sputum aspiration.Methods A prospective single-blind randomized controlled trial was conducted. The factorial analysis of variance was adopted. 150 patients with ARDS admitted to the emergency intensive care unit (ICU) of Chongqing Three Gorges Central Hospital from January 2012 to December 2014 were enrolled, and they were randomly divided into S1, S2, S3 group, with 50 patients in each group, suction pressure varying from 150, 175, to 200 mmHg (1 mmHg = 0.133 kPa) was respectively used in each group. Then the patients of each group were randomly subdivided into five subgroups of P0, P1, P2, P3, P4, with 10 patients in each group, and 0, 30, 35, 40, and 45 cmH2O (1 cmH2O = 0.098 kPa) were used for control pulmonary inflation pressure, respectively. The respiratory mechanics and the hemodynamic parameters were recorded, and they were compared before and after the sputum aspiration as well as lung recruitment with sustained inflation.Results The lung recruitment volume (mL: 87.56±28.47 vs. 109.38±34.63, t = 3.573,P = 0.001) and lung static compliance [Cst ( mL/cmH2O): 27.69±13.25 vs. 35.87±17.47,t = 2.814,P = 0.004] after sputum aspiration in the 150 patients were significantly lower than those before the sputum aspiration, and peak airway pressure [PIP (cmH2O): 24.16±8.28 vs. 18.63±6.67,t = 2.957,P = 0.005], airway plateau pressure [Pplat (cmH2O): 21.28±9.14 vs. 17.47±7.26,t = 2.089,P = 0.032], and mean airway pressure [Pm (cmH2O): 13.26±4.65 vs. 10.41±3.54,t = 3.271,P = 0.001] were significantly higher than those before the treatment. There were no significant differences in the lung recruitment volume, Cst, PIP, Pplat and Pm between groups with different negative pressure for sputum aspiration (F value was 0.809, 0.986, 1.121, 0.910, 1.043, andP value was 0.452, 0.381, 0.335, 0.410, 0.361), but statistical significance was found among different groups of different lung recruitment pressures (F value was 3.581, 5.028, 3.064, 3.036, 4.050, andP value was 0.013, 0.002, 0.026, 0.027, 0.007). There was no interaction between the two factors. After pairwise comparison, under the same negative pressure for sputum aspiration, lung recruitment volume and Cst in different lung recruitment pressures subgroups (P1, P2, P3, P4) were significantly higher than those of P0 subgroup, and PIP, Pplat, and Pm were significantly lower than those of P0 subgroup. There was no significant difference among P1, P2, P3 and P4 groups. There were no significant differences in mean arterial pressure (MAP) and pulmonary arterial pressure (PAP) among different groups with negative pressures for sputum aspiration and different lung recruitment pressures (negative pressure for sputum aspiration:F = 0.586,P = 0.561,F= 1.373,P = 0.264; lung recruitment pressure:F = 1.313,P = 0.280,F= 1.621,P = 0.186), there was no interaction between the two factors (F = 0.936,P = 0.497,F = 1.391,P = 0.227). The difference of heart rate (HR) in different negative pressure for sputum aspiration groups was not significant (F = 1.144,P = 0.328), and there were significant differences in different lung recruitment pressure groups (F = 3.297,P = 0.019), there was no interaction between the two factors (F = 1.277, P = 0.280). After pairwise comparison, under the same negative pressure for sputum aspiration, HR in P3 and P4 subgroups was significantly higher than that in P0, P1, and P2 subgroups (allP< 0.05).Conclusion 30 cmH2O and 35 cmH2O were the suitable pressure for SI in ARDS patients, and they were not affected by different negative pressure for sputum aspiration.
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Objective To investigate the clinical factors dominant in the efficacy of lung recruitment maneuver (RM) with high-level positive end-expiratory pressure (PEEP) under pressure control ventilation in patients with 2009 influenza A (H1N1)-associated acute respiratory distress syndrome (ARDS) by analyzing the clinical data of 24 patients treated with mechanical ventilation.Methods A retrospective study was carried out in a 16-bed capacity emergency intensive care unit (EICU) of the First Affiliated Hospital of China Medical University from October 2009 to January 2010.Twenty-four patients with influenza-associated ARDS were included.During pressure control ventilation,when SpO2 persisted lower than 88％ for more than 30 min,RM with high-level PEEP was initiated to normalize lung volume at 30 cmH2O for 60 s.The RM was responded as SpO2 increased more than 3％ within 15 min; otherwise,the increase below 3％ in SpO2 would be considered non-responded.Variations in respiratory mechanics,oxygen metabolism and hemodynamic parameters were measured before and after RM.Results Of 24 patients with influenza-associated ARDS,16 survived and 8 deceased.The median duration of mechanical ventilation (DMV) in EICU was 5.5 days (range from 3.5 to 12.0 days).During the entire study period,a total of 158 RMs with high-level PEEP were done,including 76 (48.1％) responded RMs (the responded group) and 82 (51.9％) non-responded RMs (the non-responded group).In survivor group,the ratio of effective RM was higher than in nonsurvivors group (66.2％ vs.33.3％,P ＜ 0.01).Compared with the data before RM,HR was increased (92.6 ± 11.8) vs.(73.0 ± 12.6),P =0.038 and MAP was decreased (66.1 ±9.3) mmHg vs.(73.9 ± 11.4) mmHg,P=0.049 during RM,and these difference were not statistically significant at 3 min after RM.The decrease in SpO2 after 134 procedures of RMs in 85.9％ patients,and the minimum value of SpO2 occurred at (2.1 ±0.6) min after RM.In the responded group,the maximum SpO2 were higher than that before RM by (6.9 ± 1.6) ％ occurred at (12.7 ±2.6) min after RM.Compared with the data before RM,SpO2 were increased (90.4 ± 4.4) ％ vs.(86.7 ± 7.6) ％,P =0.047) in responded group at 30 min after RM.The initial PEEP level in the responded group was lower than that of the non-responded group (8.6 ± 3.4) cmH2O vs.(11.3 ±4.2) cmH2O,P=0.028.The initial mean DMV in the responded group was also shorter than that in the non-responded group (4.1 ± 3.1) d vs.(5.8 ± 2.5) d,P =0.011.Furthermore,the initial dynamic lung-thorax compliance (Cdyn) was obviously higher in the responded group than that in the non-responded group (30.8 ±6.2) mL/cmH2O vs.(26.1 ±5.1) mL/cmH2O,P=0.038.Conclusion The lung RM with high-level PEEP may cause temporary hemodynamic changes and the initial PEEP level,DMV,and Cdyn may be potential factors influencing the efficacy of lung RM.
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Objective To investigate the relationship between end-tidal carbon dioxide with its related indicators and ventilation/perfusion of the acute respiratory distress syndrome (ARDS) lung,and to explore a feasible way to titrate positive end-expiratory pressure (PEEP) in clinical practice.Methods Five mixed-breed dogs with oleic acid lung injury model were mechanically ventilated at a serial PEEP trial including a recruitment maneuver (RM) before each PEEP level changed.The value of blood dynamics,end-tidal carbon dioxide partial pressure ( PetCO2 ) and arterial carbon dioxide pressure under different PEEP levels were recorded.Arterial end-tidal carbon dioxide gradient (Pa-etCO2) and dead space fraction (Vd/Vt％) were calculated.All dogs received CT scan.Lung volume under different pressure levels,and ratio and volume of alveolar closing pressure,collapsed alveoli,sufficiently and insufficiently ventilated alveoli were obtained.Alveolar opening and closing analysis were performed by non-liner regression equation.Results The mean pressure when Vd/Vt％ obtained lowest level were ( 11.2 ± 4.4 ) cm H2O(1 em H2 O =0.098 kPa),which had no significant difference when compared to alveolar closing pressure[ ( 11.5 ± 3.2 ) cm H2O ]( P ＞ 0.05 ).The fraction of insufficiently ventilated and collapsed alveoli showed a significant linear correlation with the Vd/Vt％ when PEEP was lower than Pmin ( r =0.632,P =0.004 ).There was a linear correlation between the Vd/Vt％ and the fraction of over-distended alveoli when PEEP was higher than Pmin ( r =0.770,P =0.001 ).Conclusions Closing pressure is in accordance with PEEP level after RM having reached the best ventilation/circulation ratio.The characteristics of lung collapse can be revealed by Vd/Vt％ changes after RM.To titrate PEEP for the lowest Vd/Vt％ after RM may be a feasible way to match the best ventilation and circulation effects of PEEP.
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BACKGROUND: Animal experiments showed that recruitment maneuver (RM) and protective ventilation strategy of the lung could improve oxygenation and reduce extravascular lung water. This study was to investigate the effects of RM on respiratory mechanics and extravascular lung water index ( EVLWI) in patients with acute respiratory distress syndrome (ARDS). METHODS: Thirty patients with ARDS were randomized into a RM group and a non-RM group. In the RM group, after basic mechanical ventilation stabilized for 30 minutes, RM was performed and repeated once every 12 hours for 3 days. In the non-RM group, lung protective strategy was conducted without RM. Oxygenation index (PaO2/FiO2), peak inspiratory pressure (PIP), Plateau pressure (Pplat), static pulmonary compliance (Cst) and EVLWI of patients before treatment and at 12, 24, 48, 72 hours after the treatment were measured and compared between the groups. Hemodynamic changes were observed before and after RM. One-way ANOVA, Student's t test and Fisher's exact test were used to process the data. RESULTS: The levels of PaO2/FiO2 and Cst increased after treatment in the two groups, but they were higher in the RM group than in the non-RM group (P<0.05). The PIP and Pplat decreased after treatment in the two groups, but they were lower in the RM group than in the non-RM group (P<0.05). The EVLWI in the two groups showed downward trend after treatment (P<0.05), and the differences were signifcant at all time points (P<0.01); the EVLWI in the RM group was lower than that in the non-RM group at 12, 24, 48 and 72 hours (P<0.05 or P<0.01). Compared with pre-RM, hemodynamics changes during RM were significantly different (P<0.01); compared with pre-RM, the changes were not significantly different at 120 seconds after the end of RM (P>0.05). CONCLUSIONS: RM could reduce EVLWI, increase oxygenation and lung compliance. The effect of RM on hemodynamics was transient.
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Objective To study the effects of recruitment maneuver (RM) strategy on respiratory mechanics and extravascular lung water index (EVLWI) in patients with ARDS. Method Thirty patients with ARDS were randomly divided into RM group and non-RM group. In the RM group, the patients were stabilized with basic mechanical ventilation support for 30 minutes, and then the RM was carried out and repeated once every 12 hous for 3 days. In the non-RM group, patients were supported with mechanical ventilation without RM. The variables of oxygenation index (PaO2/FiO2), peak inspiration pressure (PIP), plateau pressure (Pplat), static pulmonary compliance (Cst) and EVLWI of patients in both groups were determined before treatment and 12 h,24 h, 48 h and 72 h after treatment, and were compared them between two groups. The hemodynamic changes were monitored before and after RM.One-way ANOVA, t -test and Fisher probabilities in 2/2 table were used to process the data. Results ( 1 ) The PaO2/FiO2 and Cst in two groups showed upward trend after treatment, but they were higher in RM group than those in non-RM group ( P ＜ 0. 05 ). The PIP and Pplat of two groups both had downward trend after treatment, but they were significantly lower in RM group than those in group non-RM (P ＜0.05). (2) The EVLWI of two groups showed downward trend after treatment ( P ＜ 0.05), and the differences were significant at all intervals (F: 22.392, 8.147, P ＜ 0.01). The EVLWIs in group RM were lower than those in group non-RM at the intervals of 12 h,24 h, 48 h and 72 h separately (P ＜0.05 or P ＜ 0.01). (3) There were transient hemodynamic changes occurred during RM, and compared with pre-RM, the changes were significantly different ( P＜ 0.01 ). Compared with pre-RM, the hemodynanic changes were not significantly different 120 seconds after the end of RM ( P ＞ 0.05). Conclusions RM could reduce the EVLWI, increase oxygenation and lung compliance.The effect of RM on hemodynamics was transient.
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Objective To study the effects of lung recruitment maneuvers (RM)with different duration combined with low tidal volume (TV)ventilation in acute respiratory distress syndrome (ARDS) with pulmonary and extra-pulmonary origin(ARDSp / ARDSexp). Methods Twenty-six ARDS patients with ventilation were selected including 10 patients of ARDSp (ARDSp group) and 16 patients of ARDSexp(ARDSexp group). All patients were given intermittent high-positive end expiratory pressure (PEEP) combined with low tidal volume RM in the base of usual ventilation. Effects of different duration of RM were evaluated and compared in the patients of ARDSp / ARDSexp. Results MAP decreased and HR increased when sustaining time of RM was above 60 seconds. Significant differences were showed compared with that before treatment. MAP and HR returned to normal after RM stopped.Compared with the state before RM,Pplat and Crs increased immediately after RM (P<0.05). When RM lasted above 60 seconds, Pplat increased significantly compared with that when RM continue lasted 40-59 seconds.But Crs,OI and SpO2 didn't increase obviously. Treatment effects of RM in patients of group ARDSexp were more obviously than those in patients of ARDSp group. There were 1 case of pneumothorax and 3 cases of pneumoderma in ARDSp group and 2 cases of pneumoderma in ARDSexp group when RM lasted above 60 seconds. Conclusions RM with intermittent high-PEEP on low TV is effective to ARDS and best duration is 40～59 seconds. The patients of ARDSexp, with pulmonary interstitial edema as the main pathology, respond better to RM than patients in ARDSp with pulmonary consolidation.
ABSTRACT
Objective To investigate the effects of sustained inflation (SI) combined with small tidal volume ventilation on lung recruitment and hemodynamics in patients with acute lung injury (ALI). Methods Patients with severe trauma followed by ALI were selected for this study. Patients underwent small tidal volume ventilation (baseline) for 1 h and then SI with 20 cm H 2O?30 s(SI 1), 30 cm H 2O?30 s(SI 2), 40 cm H 2O?30 s(SI 3) and 50 cm H 2O?30 s(SI 4) for 1 h, respectively. Parameters of pulmonary mechanics and hemodynamics were measured at 1 h after baseline, SI and returning baseline, respectively. Results Compared with those of the baseline, no changes of parameters were found after SI 1 and SI 2, but EELV and Cst increased significantly after SI 3 and SI 4. Paw, PAP and PVRI decreased significantly after SI 3 and SI 4. After SI interruption, all the physiological variables returned to baseline. SI had no significant effect on HR, AP and CI. Conclusion Treatment with SI combined with small tidal volume ventilation in patients with ALI can provide lung recruitment and improve lung compliance, but it has no significant side effect on hemodynamics.
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Objective To investigate the clinical effects, therapy safety and maintenance time of recruitment maneuvers (RM) combined with lung protective strategy in patients with acute respiratory distress syndrome (ARDS). Methods Thirty-two ventilated patients with ARDS underwent RM using a pressure of 30cmH_2O for 30s, without any sedatives and neuromuscular blocking agents. Results Compared with before RM, both oxhemoglobin saturation measured by pulse oximetry (SpO_2) and partial pressure of arterial oxygen (PaO_2) were significantly increased during one hour after applying RM. SpO_2 increased significantly within two hours after RM. The peak inspiratory pressures (PIP), heart rate (HR) and Pplateau inspiratory pressures (Pplate) had not significant difference between after and before RM, but respiratory system compliance (Crs) increased markedly in one hour after RM (P