Clinical study of rapid shallow breathing index as the switching point for sequential ventilation for patients with prolonged weaning after thoracolaparotomy / 中华急诊医学杂志

ABSTRACT

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.