ObjectiveTo evaluate the effect of positive end-expiratory pressure (PEEP) on respiratory function and hemodynamics in acute lung injury (ALI) with intra-abdominal hypertension (IAH). MethodsSix pigs were anesthetized and received mechanical ventilation (MV). Volume controlled ventilation was set with tidal volumn(VT) of 8 mL/kg,respiratory rate(RR) of 16 bpm,inspired oxygen concentration (FiO2) of 0.40,and PEEP of 5 cm H2O. ALI was induced by repeated lung lavage with diluted hydrochloric acid (pH<2.5) until PaO2/FiO2 declined to 150 mm Hg or less to established ALI model. Intra-abdominal hypertension was induced by an nitrogen inflator to reach intra-abdominal pressure of 20 mm Hg. Respiratory parameters and hemodynamics were continuously recorded at different PEEP levels(5,10,15,and 20 cm H2O). Every level was maintained for one hour. ResultsPaO2/FiO2 in PEEP5,10,15 and 20 were 90±11,102±10,172±23 and 200±34 mm Hg respectively. PaO2/FiO2 in PEEP15 and 20 were significantly higher than those in PEEP5 and 10 (P<0.05). Chest wall compliance (Ccw) in PEEP5,15 and 20 were 26±3,76±15 and 85±14 mL/cm H2O respectively. Ccw in PEEP15 and 20 were significantly higher than those in PEEP5 (P<0.05). There was no significant difference in lung compliance (CL) in different PEEP levels (P>0.05). Plateau pressure(Pplat) in PEEP5,10,15 and 20 were 30±3,31±2,36±2 and 38±4 cm H2O respectively. Pplat in PEEP15 and 20 were significantly higher than those in PEEP5 and 10 (P<0.05). There was no significant difference in Pplat between PEEP15 and 20 (P>0.05). Heart rate (HR) in PEEP5,15 and 20 were 113±17,147±30,and 160±30 beat/min respectively. HR in PEEP15 and 20 were significantly higher than those in PEEP5 (P<0.05). There was no significant difference in HR between PEEP15 and 20 (P>0.05).Cardiac index (CI) in PEEP5 and 20 were 4.5±0.6 and 3.5±0.6 L·min-1·m-2 respectively. CI in PEEP20 was significantly lower than that in PEEP5 (P<0.05). There was no significant difference in CI in PEEP5,10 or 15(P>0.05). Central venous pressure(CVP) in PEEP5,15 and 20 were 12±2,17±2,and 18±3 mm Hg respectively. CVP in PEEP15 and 20 were significantly higher than those in PEEP5 (P<0.05). There was no significant difference in CVP between PEEP15 and 20 (P>0.05). There were no significant differences in MAP,SVRI,ITBVI,GEDI,PVPI,or EVLWI between different PEEP levels. ConclusionConcomitant ALI and IAH can induce great impairments in respiratory physiology. When PEEP is gradually increased,oxygenation and the respiratory function are improved without significant secondary hemodynamic disturbances.
Objective To investigate the effects of positive end-expiratory pressure (PEEP) level on end-expiratory lung volume (EELV) during assisted ventilation in chronic obstructive pulmonary disease （COPD） patients，to provide physiological evidence to guide optimal setting of PEEP level in clinical practice.Methods Eight intubated patients with acute exacerbation of COPD were recruited for the study when the patients were in relatively stable condition after treatment.The static intrinsic PEEP (PEEPistat) and dynamic intrinsic PEEP (PEEPidyn) were measured by using airway occlusion method and esophageal balloon-tipped catheter technique,respectively.Changes in EELV (ΔEELV) were measured with inspiratory capacity (IC) method.Relations between PEEP level and ΔEELV were analyzed by curve estimation method.Results ΔEELV as a function of level of PEEP was shown as a sigmoid model.The low inflection points of the curves when PEEP levels were expressed as PEEP/PEEPistat ratio，PEEP/PEEPidyn ratio or actual PEEP setting (PEEP-a) were 0.74，0.76 or 3.6 cm H2O,respectively.The corresponding ΔEELV expressed as ΔEELV/IC（%） were 9.6%，9.1% and 7.4%,respectively.Conclusions In AECOPD patients demanding mechanical ventilation，the changes of lung volume (ΔEELV) in response to progressive increase of PEEP level were shown to be a sigmoid model.Setting PEEP level at 0.74 of PEEPistat，or 0.76 of PEEPidyn can avoid the steep increase of lung volume.
Simulation of the human biological lung is a crucial method for medical professionals to learn and practice the use of new pulmonary interventional diagnostic and therapeutic devices. The study on ventilation effects of the simulation under positive pressure ventilation mode provide valuable guidance for clinical ventilation treatment. This study focused on establishing an electrical simulation ventilation model, which aims to address the complexities in parameter configuration and slow display of air pressure and airflow waveforms in simulating the human biological lung under positive pressure ventilation mode. A simulated ventilation experiment was conducted under pressure-regulated volume control (PRVC) positive pressure ventilation mode, and the resulting ventilation waveform was compared with that of normal adults. The experimental findings indicated that the average error of the main reference index moisture value was 9.8% under PRVC positive pressure ventilation mode, effectively simulating the ventilatory effect observed in normal adults. So the established electrical simulation ventilation model is feasible, and provides a foundation for further research on the simulation of human biological lung positive pressure ventilation experimental platform.
ObjectiveTo investigate different levels of positive end-expiratory pressure (PEEP) on respiratory function and hemodynamics in patients with acute respiratory distress syndrome (ARDS) complicated with intra-abdominal hypertension(IAH). MethodsThirty patients with moderate ARDS admitted in ICU between January 2012 and December 2014 were recruited in the study. They were divided into three groups according to intra-abdominal pressure (IAP),including 10 patients with normal abdominal pressure as a normal IAP group,10 patients with IAP of 12-15 mm Hg as an IAPⅠ group,and 10 patients with IAP of 16-20 mm Hg as an IAPⅡ group. The optimal level of PEEP was titrated according to the best oxygenation methods. The changes of oxygenation index (OI),respiratory mechanics and hemodynamics before and after the optimal level of PEEP were monitored and compared in all groups. The 28-day mortality and ICU stay were also compared. ResultsThe OI after titration was significantly improved compared to baseline in all groups (all P<0.01). The OI after titration in the IAPⅡ group was significantly higher than that in other two groups (all P<0.05). The static lung compliance (Cst) after titration significantly improved than baseline in all groups(all P<0.05),but no significant difference was revealed among three groups (all P>0.05). In the IAPⅡ group,the levels of PEEP,IAP,blood lactate,heart rate and airway plateau pressure after titration were significantly increased than baseline but higher than those in other two groups(all P<0.05),while the level of mean arterial pressure was significantly decreased and significantly lower than those in other two groups(all P<0.01). Meanwhile,the ICU stay was longest in the IAPⅡ group (P<0.01). There was no significant difference in 28-day mortality among three groups(all P>0.05). ConclusionsPEEP can significantly improve oxygenation in patients with ARDS complicated with IAH. The higher the IAP is,the higher the PEEP level is required. However the higher PEEP will significantly increase IAP which will cause adverse impacts on hemodynamics and can not improve the prognosis.
Objective To investigate the effects of mechanical ventilation( MV) via different tidal volume ( VT) in combination with positive end expiratory pressure( PEEP) on dogs with acute lung injury( ALI) . Methods Dog model of oleic acid-induced ALI was established. And after that animals were randomized into different MV groups ( included low VT group, VT =6 mL/kg; and high VT group, VT =20 mL/kg) and ventilated for 6 h with a PEEP of 10 cmH2O. Arterial blood gas wasmeasured before, during and after ALI model was established ( at 1 h,2 h, 4 h and 6 h during MV) . The albumin concentration in BALF and pathological change of the lung tissue were evaluated in order to determine the lung injury while animals were sacrificed after 6 h MV. Results ALI model was successfully established ( 2. 50 ±0. 80) hours after oleic acid injection. Arterial pH decreased much severer in the low VT group than the high VT group( P lt;0. 01) . PaO2 and SaO2 in ventilation groups decreased after modeling but increased after MV, and PaO2 and SaO2 were significantly higher in the low VT group than the high VT group after 6 h MV( P lt;0. 05) . PaCO2 fluctuated less in the high VT group, while it increased significantly in the low VT group after MV( P lt; 0. 01) . Oxygenation index( PaO2 /FiO2 ) was lowered after modeling( P lt; 0. 01) , decreased to about 190 mm Hg after 1 h MV. And PaO2 /FiO2 in low VT group was significantly higher than the high VT group after 6 h MV( P lt; 0. 05) . BALF albumin concentration and the lung injury score in the low VT group were both significantly lower than the high VT group( both P lt; 0. 05) . Conclusions Ventilation with PEEP could improve the oxygenation of ALI dogs, and low VT ventilation improves the oxygenation better than high VT. Otherwise, low VT could induce hypercapnia and ameliorate lung injury caused by high VT MV.
Objective To investigate whether pulse pressure variation( ΔPP) reflect the effects of PEEP and fluid resuscitation ( FR) on hemodynamic effects. Methods Twenty critical patients with acute lung injury was ventilated with volume control ( VT =8 mL/kg, Ti/Te = 1∶2) , and PaCO2 was kept at 35 to 45 mm Hg. PEEP was setted as 5 cm H2O and 15 cmH2O in randomized order. Hemodynamic parameters including cardiac index, pulse pressure, central venous pressure, etc. were monitered by PiCCO system.Measurements were performed after the application of 5 cmH2O PEEP ( PEEP5 group) and 15 cm H2OPEEP ( PEEP15 group) respectively. When the PEEP-induced decrease in cardiac index ( CI) was gt; 10% ,measurements were also performed after fluid resuscitation. Results Compared with PEEP5 group, CI was decreased significantly in PEEP15 group( P lt;0. 05) , and ΔPP was increased significantly( P lt; 0. 05) . In 14 patients whose PEEP-induced decrease in CI was gt; 10% , fluid resuscitation increased CI from ( 3. 01 ±0. 57) L·min - 1·m- 2 to ( 3. 62 ±0. 68) L·min- 1 ·m- 2 ( P lt;0. 01) , and decreased ΔPP from ( 17 ±3) % to ( 10 ±2) % ( P lt;0. 01) . PEEP15 -induced decrease in CI was correlated negatively with ΔPP on PEEP5 ( r= - 0.91, P lt;0. 01) and with the PEEP15 -induced increase in ΔPP ( r = - 0. 79, P lt;0. 01) . FR-induced changes in CI correlated with ΔPP before FR ( r =0. 96, P lt; 0. 01) and with the FR-induced decrease in ΔPP ( r= - 0. 95, P lt; 0. 01) . Conclusions In ventilated patients with ALI, ΔPP may be a simple anduseful parameter in predicting and assessing the hemodynamic effects of PEEP and FR.
ObjectiveTo investigate the antibody concentration and immune status of intensive care medical staff after vaccination against COVID-19. Methods From October 1, 2021 to February 28, 2022, the serial numbers of 47 hospitals were randomly selected by cluster stratified random sampling method. Blood samples were collected from 192 medical staff in intensive care department who had received inactivated novel coronavirus vaccine in 7 hospitals. The antibody concentration was determined by chemiluminescence method to find the antibody rule. Logistic regression analysis was used to determine the related factors affecting the production of antibodies. ResultsTotal antibody concentration of 192 blood samples was 23.25 (5.09, 270.22), IgG concentration was 0.94 (0.15, 4.48), IgM concentration was 0.05 (0.03, 0.12). Logistic regression analysis showed that the total antibody concentration might be related to gender and age, and the IgG concentration was significantly related to whether the third injection was administered. One hundred and twenty-seven people received 2 doses of inactivated vaccine, and the positive rate of IgG was the highest within 1 to 2 months, and decreased significantly after 3 months. The positive rate of IgG antibody was 95.4% within 60 days after receiving 3 doses of vaccine, 70% within 1 month after receiving the third dose of vaccine, and 100.0% within 1 to 2 months (P<0.05). The total antibody positive rate was 96.3% in people aged 17 to 35 years and 73.3% in people aged 36 to 58 years, showing statistical difference (P<0.05). The total antibody production rate of those who received the third dose of vaccine was 100.0%, and no severe case of COVID-19 occurred during the sampling period. Conclusions After the first, second, and third doses of COVID-19 vaccine, the total antibody concentration of the virus gradually increases to 100.0%, indicating initial immunity. However, the antibody concentration decreased gradually after 3 months of inoculation. The concentration of IgG in women is higher than that in men, and the concentration of antibody in young people is higher than that in middle-aged and elderly people during the same period.
ObjectiveTo explore whether positive end-expiratiory pressure (PEEP) guided by the esophageal balloon manometry is better than the ARDS Network standard of care recommendations during treating traumatic acute respiratory distress syndrome (ARDS) patients with mechanical ventilation. MethodsTwelve traumatic ARDS patients selected from September 2013 to March 2015 in ICU of Xiamen No. 3 Hospital were administrated esophageal balloor catheter and underwent mechanical ventilation with PEEP adjusted according to measurements of esophageal pressure and the ARDS Network standard of care recommendations simultaneously. According to the selection method of PEEP, the patients were divided into two groups:the esophageal pressure guided group and the ARDS Network recommendations guided group (the control group). The changes of peak inspiratory pressure, esophageal pressure, transpulmonary end-expiratory pressure, transpulmonary end-inpiratory pressure, lung compliance at 0 h, 24 h, 48 h, 72 h following different PEEP treatments were observed and compared between two groups of patients. ResultsA mean PEEP in the esophageal pressure guided group of (10.98±4.36)cm H2O was significantly higher than the control group of (7.13±2.21)cm H2O (P<0.01). The transpulmonary end-expiratory pressure was significantly higher in the esophageal pressure guided group (0.71±0.62)cm H2O than the control group (-2.29±3.49) cm H2O. And all of the mean transpulmonary end-expiratory pressure remained above zero in the esophageal pressure guided group, whereas in the control group 73% patients remained negative (P<0.01). ConclusionsEsophageal pressure method adjusts PEEP for traumatic ARDS patients with mechanical ventilation through estimating pleural pressure so as to calculate transpulmonary pressure. It can identify traumatic ARDS patients who would benefit from the high PEEP, adjust PEEP individually and meet patients' need more satisfactorily.
ObjectiveTo evaluate the correlation between positive end-expiratory pressure (PEEP) level and postoperative pulmonary complications (PPCs) in patients undergoing thoracoscopic lung surgery. MethodsThe clinical data of patients who underwent elective thoracoscopic lung surgery at West China Hospital of Sichuan University from January 2022 to June 2023 were retrospectively analyzed. Patients were divided into 2 groups according to intraoperative PEEP levels: a PEEP 5 cm H2O group and a PEEP 10 cm H2O group. The incidence of PPCs in the two groups after matching was compared using a nearest neighbor matching method with a ratio of 1∶1, setting the clamp value as 0.02. ResultsA total of 538 patients were screened, and after propensity score-matching, a total of 229 pairs (458 patients) were matched, with an average age of 53.9 years and 69.4% (318/458) females. A total of 118 (25.8%) patients had PPCs during hospitalization after surgery, including 60 (26.2%) patients in the PEEP 5 cm H2O group and 58 (25.3%) patients in the PEEP 10 cm H2O group, with no statistically significant difference between the two groups [OR=0.997, 95%CI (0.495, 1.926), P=0.915]. Multivariate logistic regression analysis showed that PEEP was not an independent risk factor for PPCs [OR=0.920, 95%CI (0.587, 1.441), P=0.715]. ConclusionFor patients undergoing thoracoscopic lung surgery, intraoperative PEEP (5 cm H2O or 10 cm H2O) is not associated with the risk of PPCs during hospitalization after surgery, which needs to be further verified by prospective, large-sample randomized controlled studies.
Objective To study the influence of low-tidal volume and positive end expiratory pressure (PEEP) protective ventilation on cardiac output volume in elderly patients under general anesthesia. Methods From August 2012 to July 2014, 60 elderly patients undergoing selective surgery were divided into three groups with 20 patients in each. Group A was treated with conventional ventilation: tidal volume at 8 mL/kg, PEEP at 0 cm H2O (1 cm H2O=0.098 kPa); group B was treated with a tidal volume of 6 mL/kg and a PEEP of 5 cm H2O; group C was treated with a tidal volume of 6 mL/kg and a PEEP of 8 cm H2O. We then observed and analyzed the blood pressure, heart rate, cardiac output, arterial blood gas and airway mean pressure before induction of anesthesia (T0), 15 minutes of mechanical ventilation after the induction of anesthesia (T1), 60 minutes after anesthesia induction (T2), and 15 minutes after tracheal extubation (T3). Results In all the three groups, the mean arterial pressure and cardiac output were stable. In group B and C, central venous pressure increased significantly, the mean airway pressure and lung compliance increased, and the arterial oxygen branch pressure also increased significantly (P < 0.05). Conclusion Low-tidal volume combined with 5-cm H2O or 8-cm H2O positive end expiratory pressure lung-protective ventilation had a small influence on the cardiac output of elderly patients under anesthesia, which can be safely used.