Gastric pressure monitoring unveils abnormal patient-ventilator interaction related to active expiration: a retrospective observational study.

BACKGROUND: Patient-ventilator dyssynchrony is frequently observed during assisted mechanical ventilation (MV). However, the effects of expiratory muscle contraction on patient-ventilator interaction are underexplored. We hypothesized that active expiration would affect patient-ventilator interaction and we tested our hypothesis in a mixed cohort of invasively ventilated patients with spontaneous breathing activity. METHODS: This is a retrospective observational study involving patients on assisted MV who had their esophageal (Pes) and gastric (Pgas) pressures monitored for clinical purposes. Active expiration was defined as Pgas rise (ΔPgas) ≥1.0 cmH2O during expiratory flow without a corresponding change in diaphragmatic pressure (Pdi). Waveforms of Pes, Pgas, Pdi, flow, and airway pressure (Paw) were analyzed to identify and characterize abnormal patient-ventilator interaction. RESULTS: We identified 76 patients with Pes and Pgas recordings, of whom 58 demonstrated active expiration with a median ΔPgas of 3.4 cmH2O (IQR=2.4-5.3) observed in this subgroup. Among these 58 patients, 23 presented the following events associated with expiratory muscle activity: (1) distortions in Paw and flow that resembled ineffective efforts, (2) distortions similar to autotriggering, (3) multiple triggering, (4) prolonged ventilatory cycles with biphasic inspiratory flow, with a median % (IQR) increase in mechanical inflation time and tidal volume of 54% (44-70%) and 25% (8-35%), respectively and (5) breathing exclusively by expiratory muscle relaxation. Gastric pressure monitoring was required to identify the association of active expiration with these events. Respiratory drive, assessed by the rate of inspiratory Pes decrease, was significantly higher in patients with active expiration (median [IQR] dPes/dt: 12.7 [9.0-18.5] vs 9.2 [6.8-14.2] cmH2O/sec; p<0.05). CONCLUSIONS: Active expiration can impair patient-ventilator interaction in critically ill patients. Without documenting Pgas, abnormal patient-ventilator interaction associated with expiratory muscle contraction may be mistakenly attributed to a mismatch between the patient´s inspiratory effort and mechanical inflation. This misinterpretation could potentially influence decisions regarding clinical management.

A combination of mild-moderate hypoxemia and low compliance is highly prevalent in persistent ARDS: a retrospective study.

BACKGROUND: The Acute Respiratory Distress Syndrome (ARDS) is characterized by lung inflammation and edema, impairing both oxygenation and lung compliance. Recent studies reported a dissociation between oxygenation and compliance (severe hypoxemia with preserved compliance) in early ARDS and COVID-19-related-ARDS (CARDS). During the pandemic, in patients requiring prolonged mechanical ventilation, we observed the opposite combination (mild-moderate hypoxemia but significantly impaired compliance). The purpose of our study was to investigate the prevalence of this combination of mild-moderate hypoxemia and impaired compliance in persistent ARDS and CARDS. METHODS: For this retrospective study, we used individual patient-level data from two independent cohorts of ARDS patients. The ARDSNet cohort included patients from four ARDS Network randomized controlled trials. The CARDS cohort included patients with ARDS due to COVID-19 hospitalized in two intensive care units in Greece. We used a threshold of 150 for PaO2/FiO2 and 30 ml/cmH2O for compliance, estimated the prevalence of each of the four combinations of oxygenation and compliance at baseline, and examined the change in its prevalence from baseline to day 21 in the ARDSNet and CARDS cohorts. RESULTS: The ARDSNet cohort included 2909 patients and the CARDS cohort included 349 patients. The prevalence of the combination of mild-moderate hypoxemia and low compliance increased from baseline to day 21 both in the ARDSNet cohort (from 22.2 to 42.7%) and in the CARDS cohort (from 3.1 to 33.3%). Among surviving patients with low compliance, oxygenation improved over time. The 60-day mortality rate was higher for patients who had mild-moderate hypoxemia and low compliance on day 21 (28% and 56% in ARDSNet and CARDS), compared to those who had mild-moderate hypoxemia and high compliance (20% and 50%, respectively). CONCLUSIONS: Among patients with ARDS who require prolonged controlled mechanical ventilation, regardless of ARDS etiology, a dissociation between oxygenation and compliance characterized by mild-moderate hypoxemia but low compliance becomes increasingly prevalent. The findings of this study highlight the importance of monitoring mechanics in patients with persistent ARDS.

Epidemiology and Management of Chronic Thromboembolic Pulmonary Hypertension in Greece. Real-World Data from the Hellenic Pulmonary Hypertension Registry (HOPE).

Chronic Thromboembolic Pulmonary Hypertension (CTEPH) is a rare disease with poor prognosis if left untreated, characterized by pulmonary vascular bed obstruction due to unresolving thromboembolic material. The Hellenic pulmonary hypertension registry (HOPE) was launched in Greece in early 2015 and enrolls patients from all pulmonary hypertension subgroups in Greece. In total, 98 patients with CTEPH were enrolled from January 2015 until November 2019. Of these patients, 55.1% represented incident population, 50% were classified in the World Health Organization functional class II and 49% had a history of acute pulmonary embolism. The median values of pulmonary vascular resistance (PVR) and cardiac index were 7.4 (4.8) WU and 2.4 (1.0) L/min/m2, respectively, the mean diffusing capacity for carbon monoxide was 74.8 ± 20.6%, the median 6-minute walk distance was 347 (220) meters and the median value of N Terminal-pro brain natriuretic peptide was 506.0 (1450.0) pg/mL. In total, 60.2% of the patients were under pulmonary arterial hypertension-targeted therapy at the time of enrolment; specifically, riociguat was received by 35.7% of the patients and combination therapy was the preferred strategy for 16% of the patients. In total, 74 patients were evaluated for pulmonary endarterectomy (PEA), 34 (45.9%) were assessed as operable but only 23 of those (31.1%) finally underwent PEA. The remaining 40 patients were ineligible for PEA according to the operability assessment and 13 (17.6%) of them underwent balloon pulmonary angioplasty. The age of the non-operable patients was significantly higher than the operable patients (p < 0.001), while there was no significant difference with regard to the history of coagulopathies between the operable and non-operable patients (p = 0.33).

Real-life Cretan asthma registry focused on severe asthma: On behalf of 'The Cretan registry of the use of Biologics in Severe Asthma'.

Asthma diagnosis and management remains a challenging task for the medical community. The aim of the present study was to present the functional and inflammatory profiles of patients with difficult-to-treat asthma in a real-life clinical setting referred to the specialized asthma clinic at the University Hospital of Heraklion. The registry included a cohort of 267 patients who were referred to the severe asthma clinic. Patients were assessed with emphasis on the history of allergies, nasal polyposis or other comorbidities. Blood testing for eosinophils counts and total and specific IgE, and pulmonary function tests were performed at baseline. The median age of patients with asthma was 55 years old, 68.5% were women and 58.3% were never smokers. The vast majority presented with late onset asthma (75.7%), whereas eight (3%) patients were on oral corticosteroids. The median number of exacerbations during the last 12 months was 1 (0-3). Furthermore, 50.7% of patients had a positive serum allergy test, the median eosinophil count was 300 (188-508.5) cells/µl of blood and median total IgE level was 117.5 (29.4-360.5) IU/ml. Patients were retrospectively grouped in the following categories: Group 1, mild-moderate asthma; group 2, patients prescribed a step 4 or 5 asthma therapy according to Global Initiative for Asthma; and group 3, patients on biologic agents. Group 1 had significantly higher FEV1% than groups 2 and 3 (93.4 vs. 79.9 and 79.4%, respectively; P<0.001). Finally, the median Asthma Control Questionnaire 7 (ACQ7) score was 1.14, with patients from groups 2 and 3 presenting higher ACQ7 scores compared with group 1 patients as expected (1.1 and 2.1 vs. 0.7, respectively; P<0.001). To the best of our knowledge, this was the first real-life asthma study in Crete that demonstrated that severe asthmatics predominantly have late-onset asthma with airflow obstruction and uncontrolled symptoms.