OBJECTIVE: To evaluate the safety and clinical therapeutic effect of in-line mechanical in-exsufflation to assist sputum clearance in patients with invasive mechanical ventilation. METHODS: A prospective observational study was conducted at the department of critical care medicine, the First Affiliated Hospital of Sun Yat-sen University from April 2022 to May 2023. Patients who were invasively ventilated and treated with in-line mechanical in-exsufflation to assist sputum clearance were enrolled. Baseline data were collected. Sputum viscosity, oxygenation index, parameters of ventilatory function and respiratory mechanics, clinical pulmonary infection score (CPIS) and vital signs before and after day 1, 2, 3, 5, 7 of use of the in-line mechanical in-exsufflation were assessed and recorded. Statistical analyses were performed by using generalized estimating equation (GEE). RESULTS: A total of 13 invasively ventilated patients using in-line mechanical in-exsufflation were included, all of whom were male and had respiratory failure, with the main cause being cervical spinal cord injury/high-level paraplegia (38.46%). Before the use of the in-line mechanical in-exsufflation, the proportion of patients with sputum viscosity of grade III was 38.46% (5/13) and decreased to 22.22% (2/9) 7 days after treatment with in-line mechanical in-exsufflation. With the prolonged use of the in-line mechanical in-exsufflation, the patients' CPIS scores tended to decrease significantly, with a mean decrease of 0.5 points per day (P < 0.01). Oxygenation improved significantly, with the oxygenation index (PaO₂/FiO₂) increasing by a mean of 23.3 mmHg (1 mmHg ≈ 0.133 kPa) per day and the arterial partial pressure of oxygen increasing by a mean of 12.6 mmHg per day (both P < 0.01). Compared to baseline, the respiratory mechanics of the patients improved significantly 7 days after in-line mechanical in-exsufflation use, with a significant increase in the compliance of respiratory system (Cst) [mL/cmH₂O (1 cmH₂O ≈ 0.098 kPa): 55.6 (50.0, 58.0) vs. 40.9 (37.5, 50.0), P < 0.01], and both the airway resistance and driving pressure (DP) were significantly decreased [airway resistance (cmH₂O×L^-1×s^-1): 9.6 (6.9, 10.5) vs. 12.0 (10.0, 13.0), DP (cmH₂O): 9.0 (9.0, 12.0) vs. 11.0 (10.0, 15.0), both P < 0.01]. At the same time, no new lung collapse was observed during the treatment period. No significant discomfort was reported by patients, and there were no substantial changes in heart rate, systolic blood pressure, diastolic blood pressure, and mean arterial pressure before and after the in-line mechanical in-exsufflation treatment. CONCLUSIONS The combined use of the in-line mechanical in-exsufflation to assist sputum clearance in patients on invasive mechanical ventilation can effectively improve sputum characteristics, oxygenation and respiratory mechanics. The in-line mechanical in-exsufflation was well tolerated by the patients, with no treatment-related adverse events, which demonstrated its effectiveness and safety.
Humans ; Prospective Studies ; Respiration, Artificial/methods* ; Respiratory Insufficiency/therapy* ; Sputum

Objective To investigate the mechanism of soluble β-1, 3-D-glucan in G-test positive serum in inhibiting ROS-dependent killing of Candida albicans ( C.albicans ) mediated by neutrophil Dectin-1.Methods The expression and distribution of internalized Dectin-1 and triggered ROS in human neutrophils were detected by using confocal/two-photon laser scanning microscopy upon stimulation with C.albicans (MOI=10) which was pretreated with β-1, 3-D-glucanase (10 U/ml) or not.Abrogation test was used to analyze whether intracellular Dectin-1 was involved in C.albicans-triggered ROS production in human neutrophils.Furthermore, flow cytometry analysis was performed to detect the expression of intracel-lular Dectin-1 and ROS in neutrophils which were pretreated respectively with G-test positive serum at differ-ent dilutions for 60 min and then stimulated with C.albicans for another 60 min at 37℃.Results After stimulated with C.albicans (MOI=10) for 60 min, the expression of Dectin-1 in neutrophils was recruited to the spores of opsonophagocytized C.albicans, and partly co-localized with the triggered ROS production . However, the expression of intracellular Dectin-1 was not observed in neutrophils when stimulated with β-1, 3-D-glucanase pretreated C.albicans for 60 min at 37℃.Abrogation test further showed that C.albicans-trig-gered ROS production in neutrophils was partly and irreversibly inhibited by adding Dectin -1 blocking mAb of 5 μg/ml.In addition , both the triggered expression of intracellular Dectin-1 and ROS production in neu-trophils stimulated with C.albicans ( MOI=10 ) in the presence of G-test positive serum were significantly lower than those of neutrophils stimulated only with C.albicans (LSD-t test, P<0.01).Linear regression a-nalysis suggested that the triggered intracellular Dectin-1 and ROS production in neutrophils upon stimulation with C.albicans were both inhibited by soluble β-1, 3-D-glucan in a dose-dependent manner (Dectin-1,R2=0.702,P<0.01;ROS,R2=0.588,P<0.01 ).Conclusion Taken together, these results demonstrated that the soluble β-1, 3-D-glucan in G-test positive serum may play a role in inhibiting the ROS-dependent killing of C.albicans by interfering with internalized expression of neutrophil Dectin-1.

Objective To investigate the mechanism hy which Dectin-1 mediates the killing of Candida albicans(C.albicans) by human neutrophils in a manner dependent on the production of reactive oxygen species (ROS).Methods After stimulation with FITC-C.albicans at a multiplicity of infection (MOI) of 10 for 30 or 60 min,PE-anti-human Dectin-1 monoclonal antibody (2.5 μg/106 cells) was used to detect the expression of Dectin-1 in human neutrophils by flow cytometry.For Dectin-1 inhibition test and ROS assay,human neutrophils (2×106/ml) were respectively pre-incubated with different concentrations of blocking antibody (0.5,1,2.5 and 5 μg/ml) for 60 min at 4℃,and then with 25 μmol/L 2′,7′-Dichlorofluorescein diacetate for another 20 min at room temperature.Afterwards,under stimulation with live C.albicans at a MOI of 10,the rate of intracellular ROS production over time in blocking and control groups was measured continuously at 10 min intervals for up to 120 min.In addition,localization of Dectin-1 and ROS in human neutrophils was observed by confocal/two-photon laser scanning microscopy after stimulation with live C.albicans.For the detection of candicidal activity,after pre-treatment with different concentrations of Dectin-1 blocking antibody as mentioned above,neutrophils were stimulated with live C.albicans (MOI=1) for 60 min,serial dilutions of cell lysate were plated onto yeast agar,and CFU were enumerated after incubation at 37℃ for 48 h.The candicidal activity was represented as [1-(CFUblocking group/CFUbuffer)] × 100％.Results Under stimulation with FITC-C.albicans at a MOI of 10 for 30 and 60 min,positive percentage of intracellular Dectin-1-expressing neutrophils increased significantly when compared with initial level (0 min,8.32％ ; 30 min,16.82％ ; 60 min,23.88％) (versus 0 min,P＜0.01).However,positive percentage of cell-surface Dectin-1-expressing neutrophils remained almost unchanged after stimulation for 30 and 60 min (versus 0 min,P＞0.05).Upon blockage of Dectin-1,the stimulated ROS generation (R2=0.306,P＜0.01) and candicidal activity (R2=0.251,P＜0.01) of neutrophils were partly and irreversibly inhibited in a dose-dependent manner when compared with control group.In addition,the intracellular Dectin-1 is recruited and co-distributed with ROS on the surface of phagocytized C.albicans as observed by confocal microscopy.Conclusion Taken together,these results demonstrated that an internalized expression pattern of human Dectin-1 might contribute to the ROS-dependent killing of serum-opsonzied C.albicans which was phagocytized by human neutrophils.