Comparative Study On Different Modes Of Random Respiratory Support Before And After Weaning In Patients With Difficulty In Weaning

BackgroundSpontaneous breathing trials(SBTs)are a necessary step in the protocolized weaning of mechanically ventilated patients.To improve the success rate of extubation,shorten the duration of hospitalization,and reduce complications and mortality are not only the efforts of clinicians,but also an important and difficult point.Many methods are used in SBTs,low-level pressure support ventilation(PSV)is most commonly adopted in SBTs,and some have proposed setting the positive endexpiratory pressure(PEEP)to 0 cmH2O in order to shorten the observation time of SBTs.The use of PEEP can keep the alveoli open,which may be more beneficial for weaning of mechanically ventilated patients.Sequential respiratory support after extubation is a common means for clinicians to improve the short-term and long-term prognosis of patients,including conventional oxygen therapy(COT),non-invasive positive pressure Ventilation(NIV)and high-flow nasal cannula oxygen therapy(HFNC).The three have their own advantages in patients with different types of diseases and critical conditions.There are few studies to directly compare the similarities and differences of respiratory mechanics among the three,explore the effects of the three on the respiratory mechanics of patients is of great significance.OBJECTIVEPart 1:To investigate the effects of two PSV protocols on respiratory mechanics of patients with difficult weaning.Part 2:To investigate the effects of three random respiratory support modes on respiratory mechanics in patients with difficult weaning.METHODS:Part 1:A prospective randomized self-controlled crossover design was adopted in this study,which involved enrolling 30 difficult-to-wean patients who were admitted to the intensive care unit of our hospital between July 2019 and September 2021.Patients were subjected to the S protocol(Pressure Support:8 cmH2O,PEEP:5 cmH2O)and S1 protocol(PS:8 cmH2O,PEEP:0 cmH2O)for 30 min in a random order,and collect the following ventilator-related indicators:respiratory rate(RR)、rapid shallow breathing index(RSBI)、inspiratory time(Ti)、expiratory time(Te)、total time-over-threshold(Ttot);and respiratory mechanics indices were dynamically monitored via a four-lumen multi-functional catheter with an integrated gastric tube:airway pressure(Paw)、esophageal pressure(Pes)、gastric pressure(Pga)、transdiaphragmatic pressure(Pdi)、diaphragmatic electromyogram(EMGdi),and percentage of esophageal pressure coefficient of variation(CVes)、pressure-time product of esophageal pressure(PTPes)、pressure-time product of gastric pressure(PTPga)、pressure-time product of transdiaphragmatic pressure(PTPdi)、Pes/Pdi、PTPdi/PTPes were calculated.The inspiratory trigger delay was calculated based on the time difference between inspiratory onset and ventilator flow delivery determined using esophageal pressure,the frequency of abnormal triggers within 2 min was calculated,and the asynchrony index(%)(AI)was calculated using the central respiratory frequency within 2 min.Part 2:A prospective randomized self-controlled crossover design was adopted in this study,which involved enrolling 15 difficult-to-wean patients who were admitted to the intensive care unit of our hospital between February 2019 and June 2021.Within 48 hours after extubation,patients were given sequential respiratory support with COT,NIV and 40 L/min HFNCfor 30 minutes.Collect the following ventilator-related indicators:RR、RSBI、Ti、Te、Ttot;and respiratory mechanics indices were dynamically monitored via a four-lumen multi-functional catheter with an integrated gastric tubePaw、Pes、Pga、Pdi、EMGdi,and CVes、PTPes、PTPga、PTPdi、Pes/Pdi、PTPdi/PTPes were calculated.RESULTS:Part 1:Among the 30 enrolled patients,27 were successfully weaned.The S group showed higher airway pressure,intragastric pressure,and airway pressure-time product than the S1 group.The S group also showed a shorter inspiratory trigger delay,(93.80±47.85)vs(137.33±85.66)ms;and fewer abnormal triggers,(0.97±2.65)vs(2.67±4.48)compared to the S1 group.Stratification based on the causes of mechanical ventilation revealed that under the S1 protocol,patients with chronic obstructive pulmonary disease had a longer inspiratory trigger delay compared to both post-thoracic surgery patients and patients with acute respiratory distress syndrome.The esophageal pressure of patients with acute respiratory distress syndrome was lower than that of post-thoracic surgery patients,(8.76± 12.64)vs(1.05±2.98)cmH2O,the pressure-time product of esophageal pressure with acute respiratory distress syndrome was lower than that of post-thoracic surgery patients,(1.38(-1.59,4.25))vs(5.53(2.16,9.93))cmH2O(P<0.05).Part 2:A total of 15 patients with difficulty in weaning were included and monitored in 15 groups.All the patients were weaned successfully and all survived at 30 days,60 days and 90 days.There was statistical difference in Te:HFNC vs NIV vs COT(1.58(1.41,2.29)vs 1.87(1.57,2.44)vs 1.56(1.41,2.10),and other indexes had no significant difference.CONCLUSION:Part 1:Despite providing greater respiratory support,S protocol led to significant reductions in inspiratory trigger delay and abnormal triggers compared to S1 protocol(PEEP:0 cmH2O),especially among patients with chronic obstructive pulmonary disease.These findings suggest that the S1 protocol was more likely to induce a higher number of patient-ventilator asynchronies in difficult-to-wean patients.Part 2No significant differences were observed in the respiratory mechanical indices in the short-term alternating sequential HFNC,NIV and COT in patients with difficulty weaning after extubation,thus suggesting that HFNC,NIV and COT can be used alternately for a short time when patients receive sequential respiratory support after extub ati on.