Objective To investigate the correlation between dynamic intrinsic positive endexpiratory pressure ( PEEPidyn) and volume dependence of elastance and resistance of respiratory system ( Evd/Rvd) derived from nonlinear analysis of respiratory mechanics in COPD patients during pressure support ventilation ( PSV) . Methods Twenty-five COPD patients mechanically ventilated using mode of PSV were ventilated at a PSV level of no less than 20 cm H2O in a period of 15 minutes to attain so-callednear-relaxation state. The pressure( P) , flow( V′) and volume( V) data were analyzed by nonlinear mode of respiratory motion. PEEPidyn was determined by esophageal balloon-tipped catheter technique. The correlations between PEEPidyn and Evd, Rvd as well as Evd ×Rvd were analyzed. Results The correlation coefficients between PEEPidyn and Evd, Rvd as well as Evd ×Rvd were 0. 85,0. 80, and 0. 90, respectively. Conclusions Nonlinear mode of respiratory motion is suitable to analyze respiratory mechanics of COPD patients mechanically ventilated using mode of PSV. There are good correlations between PEEPidyn and Evd,Rvd as well as Evd ×Rvd which may be used to noninvasively monitor PEEPidyn in mechanically ventilated COPD patients using mode of PSV.
Objective To explore the clinical application value of electrical impedance tomography (EIT) individualized adjustment of positive end-expiratory pressure (PEEP) in patients with acute respiratory distress syndrome (ARDS). Methods The ARDS patients requiring mechanical ventilation who admitted between April 2019 and March 2022 were recruited in the study. They were randomly divided into 3 groups with 12 cases in each group. Optimal PEEP was set using ARDSnet method (a control group), lung ultrasound scoring method (LUS group) and EIT adjustment method (EIT group). The changes of hemodynamics, blood gas analysis, respiratory mechanics, extravascular lung water index and other indicators of the patients were recorded at each time point. Results There was no significant difference in PEEP between the EIT group and the LUS group, but PEEP in both the EIT group and the LUS group was significantly higher than the control group (P<0.05). After 12 hours of treatment, the dynamic lung compliance of the control group did not change significantly, while the dynamic lung compliance ventilation of the LUS group and the EIT group was significantly improved for 12 hours, and the improvement in the EIT group was significantly better than that in the control group (P<0.05). After treatment, the oxygenation index in the three groups was significantly increased, and the oxygenation index in the EIT group was significantly higher than that in the control group (P<0.05). There was no significant difference in hemodynamics between the three groups before and after treatment (P>0.05). The extravascular lung water index of the three groups after treatment was significantly decreased, and the LUS group and the EIT group decreased more significantly than the control group (P<0.05). Conclusion In the PEEP setting of ARDS patients, the use of EIT personalized adjustment method can effectively improve the patient’s lung compliance and oxygenation index, and reduce extravascular lung water, without affecting hemodynamics.
Objective To investigate the guiding value of bedside lung ultrasound and lung stretch index for optimal positive end-expiratory pressure (PEEP) in lung recruitment of patients with acute respiratory distress syndrome (ARDS). Methods From February 2020 to October 2023, 90 patients with ARDS requiring invasive mechanical ventilation were selected from the Department of Critical Care Medicine, the Second Affiliated Hospital of Zhengzhou University. According to the setting method of PEEP after lung recruitment, they were randomly divided into an ultrasound group (45 cases) and a stretch group (45 cases). Both groups were treated with PEEP incremental method for lung recruitment, and the ultrasound group was treated with bedside ultrasound-guided method to set PEEP after lung recruitment. PEEP was set by lung stretch index method in the stretch group. The dynamic changes of oxygenation index (PaO2/FiO2), dynamic compliance (Cdyn), mean airway pressure and peak airway pressure were monitored before lung recruitment and 15 min, 1 h, 6 h and 24 h after lung recruitment. Heart rate, mean arterial pressure and central venous pressure were monitored before and 24 h after lung recruitment in the two groups. The optimal PEEP value and the corresponding volume at the end of recruitment were explored. The mechanical ventilation time, ICU hospitalization time, incidence of barotrauma, incidence of extrapulmonary organ failure, and 28-day mortality were recorded as well. Results After lung recruitment, the oxygenation index, Cdyn, mean airway pressure, and peak airway pressure in the ultrasound group were higher than those in the stretch group at 15 min, 1 h, 6 h, and 24 h after recruitment (all P<0.05). There was no significant difference in heart rate, mean arterial pressure or central venous pressure between the two groups at 24 h after lung recruitment (all P>0.05). After lung recruitment, the optimal PEEP value and the corresponding volume at the end of recruitment in the ultrasound group were higher than those in the distraction group (both P<0.05). The mechanical ventilation time and ICU stay in the ultrasound group were shorter than those in the stretch group (both P<0.05). There was no significant difference in the incidence of barotrauma, extrapulmonary organ failure rate or 28-day mortality between the two groups (all P>0.05). Conclusions Both bedside lung ultrasound-guided PEEP and lung stretch index-guided PEEP can improve oxygenation and respiratory compliance, and have no adverse effects on hemodynamics. Bedside lung ultrasound-guided PEEP can make the alveoli fully expand, which is more conducive to improving patients’ oxygenation and respiratory compliance, and the guiding value is higher than the lung stretch index.