RESUMO
Objective To investigate the influencing factors of successfully switching to sequential ventilation in patients with prolonged weaning due to acute respiratory failure (ARF) after thoracolaparotomy based on the initial rapid shallow breathing index (RSBI) at 60 min after spontaneous breathing trial (SBT), namely, the f/VT optimal value range of 80-120 times/ (min · L), thus providing the basis for determining the ideal timing of weaning in clinical practice.Methods A prospective observational study of sequential ventilation [RSBI during the initial SBT (60 min), 80-120 breaths/ (min · L)] was carried out in 42 patients on mechanical ventilation (≥ 48 h) due to post-thoracolaparotomy ARF in the ICUs.According to the duration of the mechanical ventilation, the patients were divided into 2 groups : successfully prolonged weaning group (≥ 7 days, n =24) and refractory weaning group (＜ 7 days, n =18).The patients with cardiac failure, aged less 18 or over 80, with hepatic dysfunction, or those needing gastrointestinal decompression after esophageal surgery or upper abdomen surgery were excluded.The demographics, APACHE Ⅱ scores and duration of mechanical ventilation of both groups were recorded, and the respiratory work and oxygen metabolism variables before the switch to sequential ventilation (within 24 hours after admission to ICU) and at the time of switching (24 hours in the ICU after admission) were recorded, respectively: clinical puhnonary infection score (CPIS), assessment of cough severity, pH, PaO2, PaCO2 and PaO2/FiO2;hemodynamic and microcirculation-related variables: HR, MAP, fluid balance, BNP and Lac;endocrine and metabolism variables : Hb, ALB and random serum cortisol (COR).The clinical features and the changes of the above-mentioned variables before and at the time of switching were compared between both groups.The independent sample t test was used for the single factor comparison and Mann-Whitney U test was applied to the non-normal distributions.The Fisher exact probability test was used for the single factor comparison of ranked data such as categorical variables.Results There were no significant differences in age, gender and severity of disease between two groups (P ＞ 0.05);the successfully prolonged weaning group had longer duration of invasive mechanical ventilation and ICU stay compared with the refractory weaning group (P ＜ 0.05).There were significant differences in cough severity, PaCO2, pH, HR and fluid balance between two groups before switching (P ＜ 0.05).Compared with those before switching, in the refractory weaning group there were marked decrease in Lac (P ＜ 0.05), obvious increase in cough severity, pH, Hb and ALB (P ＜ 0.05), but there was no significant difference in COR (P ＞ 0.05);while in the successfully delayed weaning group, there were significant decrease in CPIS, PaCO2, HR, MAP, BNP, fluid balance and Lac (P ＜ 0.05), and cough severity, pH, ALB and COR showed an upward trend (P ＜ 0.05).Conclusions The key of successful sequential ventilation is within the values of RSBI ranging from 80 to 120 times/ (min · L) during the initial SBT (60 min) selected as the switching point in patients with prolonged weaning after thoracolaparotomy.The major influencing factors for determining the ideal timing of switching include the matching status between respiratory endurance and respiratory work, the balance between myocardial strength and both cardiac preload and afterload, the severe disease associated with adrenal insufficiency, and malnutrition.
RESUMO
Objective To investigate the timing and value of noninvasive ventilation (NIV) as a weaning tool immediately after early extubation in patients with acute respiratory distress syndrome (ARDS).Methods A prospective randomized controlled trial was conducted.The ARDS patients with surgical diseases admitted to Department of Respiratory Intensive Care Unit (RICU) of the First Affiliated Hospital of Xinjiang Medical University were enrolled.The patients were randomly divided into sequential group and control group.All patients underwent endotracheal intubation and were mechanically ventilated.Every 12 hours during the first 3 days,the lung recruitment maneuver was performed during pressure control ventilation (PCV).After lung recruitment,all patients were ventilated with synchronized intermittent mandatory ventilation (SIMV) + pressure support ventilation (PSV) + positive end-expiratory pressure (PEEP) or assistant/control ventilation (A/C).The objects in sequential group who met the following criteria including those with oxygen index (PaO2/FiO2) reaching 200-250 mmHg (1 mmHg=0.133 kPa) under PEEP of 8 cmH2O (1 cmH2O =0.098 kPa),and pressure support of 12 cmH2O,and most acute infiltrating lesions having resolved on chest imaging,received noninvasive ventilation (NIV) immediately after extubation,and patients in control group continued to have invasive mechanical ventilation via intubation or tracheostomy with an endotracheal tube.The baseline data in both groups and the number of re-intubation in the sequential group were recorded.The duration of invasive mechanical ventilation and total duration of mechanical ventilation,ICU length of stay,the incidence of ventilator-associated pneumonia (VAP),and mortality rate were compared between the two groups.Results 53 consecutive adult patients were enrolled,including 26 in sequential group and 27 cases in control group.The period of endotracheal intubation was 7.0 (6.8,9.5) days,and 7.7％ (2/26) patients underwent re-intubation in sequential group.There were significant difference in respiratory and circulatory indicators before extubation spontaneous breathing trial (SBT) ≤10 minutes in sequential group,indicating that the patients were still in the early stage of extubation sequential NIV.There was no significant difference in indices reflecting respiratory function and circulation between the two groups,except that respiratory rate at 1 hour was slightly increased in sequential group as compared with that of control group,indicating that sequential NIV could maintain invasive ventilation function.There was significant difference in duration of invasive mechanical ventilation [days:7.0 (6.8,9.5) vs.21.0 (17.0,25.0),Z=-6.048,P=0.000],duration of total mechanical ventilation (days:18.0 ± 4.1 vs.22.0 ± 7.3,t=-2.805,P=0.008),and length of ICU stay (days:21.0 ± 4.1 vs.28.0 ± 8.1,t=-4.012,P=0.000) between sequential group and control group,but there was no significant differences in the incidence of VAP [15.4％ (4/26) vs.29.6 (8/27),x2=1.535,P=0.215] and mortality rate [7.7％ (2/26) vs.18.5％ (5/27),P=0.420].Conclusion When PaO2/FiO2 reached 200-250 mmHg under the condition of low ventilation,sequential NIV facilitates the early discontinuation of mechanical ventilation in ARDS patients with surgical diseases,with shortening of duration of invasive mechanical ventilation,total mechanical ventilation,and the length of ICU stay.