The controller maintained the arterial blood gases within normal limits under steady-state conditions and the transient response of the system was robust under various disturbances. The results of the study have showed that the proposed dual closed-loop technique has effectively controlled mechanical ventilation under different test conditions.

BACKGROUND: Lung expansion therapy is often ordered after surgery to improve alveolar ventilation and reduce risks of postoperative pulmonary complications. The impact of lung expansion therapy at altering ventilation in patients who are not intubated has not been described. The primary purpose of this study was to determine if there is a difference in dorsal redistribution of ventilation and incidences of postoperative pulmonary complications when comparing incentive spirometry (IS) with Ez-PAP lung expansion therapy after upper abdominal surgery. Our a priori null hypothesis was that there are no differences. METHODS: This randomized controlled trial enrolled adult human subjects after upper-abdominal surgery from January 2017 to November 2018. The subjects were allocated to receive IS or EzPAP 3 times a day on postoperative days 1-5. An electrical impedance tomography device was connected to the subjects for a single lung expansion therapy session on postoperative days 1, 3, and 5 to measure the change in post-lung expansion therapy dorsal end-expiratory lung impedance (⌬EELI%). Lung expansion therapy sessions with electrical impedance tomography included 2 min of normal breathing, 3 cycles of 10 breaths, and 2 min of normal breathing after cycle 3. Postoperative pulmonary complications were screened until hospital discharge. Mann-Whitney, chi-square, and Fisher exact tests were applied. Data were reported as count (n), percentage, and median (interquartile range) for primary and secondary outcomes. Alpha (2-tailed) was < 0.05. RESULTS: A total of 112 subjects were enrolled to receive IS (n ‫؍‬ 56) or EzPAP (n ‫؍‬ 56). Baseline characteristics were equal. Post-lung expansion therapy dorsal ⌬EELI% increased for both groups, but the dorsal ⌬EELI% for IS versus EzPAP on postoperative day 1 (16% versus 12%, P ‫؍‬ .39), postoperative day 3 (6% versus 6%, P ‫؍‬ .68), and postoperative day 5 (9% versus 6%, P ‫؍‬ .46) was not significantly different. Hospital length of stay (4 d; P ‫؍‬ .30) and incidence of postoperative pulmonary complications (3.6% versus 7.1%, P ‫؍‬ .19) were similar. CONCLUSIONS: There was no significant post-lung expansion therapy dorsal ⌬EELI% or postoperative pulmonary complications among the adults who received IS or EzPAP 3 times a day after upper abdominal surgery. (ClinicalTrials.gov registration NCT02892773.)Dräger provided an electrical impedance tomography device and electrode belts.

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BACKGROUND: The purpose of this retrospective medical record review was to report on recidivism to the ICU among adult postoperative cardiac and thoracic patients managed with a respiratory therapy assess-and-treat (RTAT) protocol. Our primary null hypothesis was that there would be no difference in all-cause unexpected readmissions and escalations between the RTAT group and the physician-ordered respiratory care group. Our secondary null hypothesis was that there would be no difference in primary respiratory-related readmissions, ICU length of stay, or hospital length of stay. METHODS: We reviewed 1,400 medical records of cardiac and thoracic postoperative subjects between January 2015 and October 2016. The RTAT is driven by a standardized patient assessment tool, which is completed by a registered respiratory therapist. The tool develops a respiratory severity score for each patient and directs interventions for bronchial hygiene, aerosol therapy, and lung inflation therapy based on an algorithm. The protocol period commenced on December 1, 2015, and continued through October 2016. Data relative to unplanned admissions to the ICU for all causes as well as respiratory-related causes were evaluated. RESULTS: There was a statistically significant difference in the all-cause unplanned ICU admission rate between the RTAT (5.8% [95% CI 4.3-7.9]) and the physician-ordered respiratory care (8.8% [95% CI 6.9 -11.1]) groups (P ‫؍‬ .034). There was no statistically significant difference in respiratory-related unplanned ICU admissions with RTAT (36% [95% CI 22.7-51.6]) compared with the physician-ordered respiratory care (53% [95% CI 41.1-64.8]) group (P ‫؍‬ .09). The RTAT protocol group spent 1 d less in the ICU (P < .001) and in the hospital (P < .001). CONCLUSIONS: RTAT protocol implementation demonstrated a statistically significant reduction in all-cause ICU readmissions. The reduction in respiratory-related ICU readmissions did not reach statistical significance.

The results of the study attest to the reliability of the proposed closed-loop control scheme for automatic adjustment of FIO2. Further evaluation of the controller will require testing the effectiveness of the system on different patient groups.