Inspiratory Airway Resistance in Respiratory Failure Due to COVID-19.

To measure inspiratory airflow resistance in patients with acute respiratory distress syndrome (ARDS) due to COVID-19. DESIGN: Observational cohort of a convenience sample. SETTING: Three community ICUs. SUBJECTS: Fifty-five mechanically ventilated patients with COVID-19. INTERVENTIONS: Measurements of ventilatory mechanics during volume control ventilation. MEASUREMENTS: Flow-time and pressure-time scalars were used to measure inspiratory airways resistance. RESULTS: The median inspiratory airflow resistance was 12 cm H2O/L/s (interquartile range, 10-16). Inspiratory resistance was not significantly different among patients with asthma or chronic obstructive pulmonary disease compared with those without a history of obstructive airways disease (median 12.5 vs 12 cm H2O/L/s, respectively; p = 0.66). Survival to 90 days among patients with inspiratory resistance above 12 cm H2O/L/s was 68% compared with 60% for patients below 12 cm H2O/L/s (p = 0.58). Inspiratory resistance did not correlate with C-reactive protein, ferritin, Pao2/Fio2 ratio, or static compliance. CONCLUSIONS: Inspiratory airflow resistance was normal to slightly elevated among mechanically ventilated patients with ARDS due to COVID-19. Airways resistance was independent of a history of obstructive airways disease, did not correlate with biomarkers of disease severity, and did not predict mortality.

Use of Handheld Ultrasound to Estimate Right Atrial Pressure in a Pulmonary Hypertension Clinic.

Rationale: Point-of-care ultrasonography is an invaluable asset for inpatient decision-making. Whether handheld ultrasound can be used in the outpatient management of pulmonary hypertension is unknown. Objectives: We investigated whether a handheld ultrasound estimate of right atrial pressure correlates with B-type natriuretic peptide (BNP) and clinical outcome over time in outpatients with pulmonary hypertension. Methods: This prospective study included outpatients in a Pulmonary Hypertension Comprehensive Care Center clinic who had a same-day BNP concentration. We used a handheld ultrasound to measure inferior vena cava size and collapsibility, which were used to estimate right atrial pressure (eRAP) and categorize it as normal, intermediate, or high. Correlation analysis was used to compare these ultrasound measurements with BNP at baseline and over time. Cox regression was used to determine whether these measurements were associated with time to clinical worsening. Results: Ninety patients (60% Group 1 pulmonary hypertension) were enrolled. Patients with an intermediate or high eRAP category at baseline had higher BNP concentrations than patients with normal eRAP. For every transition in eRAP category (e.g., from normal to intermediate) between clinic visits, BNP changed by an average of 155 pg/ml (95% confidence interval [CI], 84-227). Higher baseline eRAP category was independently associated with more than twofold increased risk for clinical worsening (hazard ratio, 2.44; 95% CI, 1.47-4.07). Conclusions: Right atrial pressure estimated by portable handheld ultrasound correlates with BNP at baseline and serially over time. Furthermore, eRAP is independently associated with clinical worsening. The use of portable handheld ultrasound to estimate right atrial pressure should be considered in pulmonary hypertension clinics. Clinical trial registered at clinicaltrials.gov (NCT02873039).

The combined mode of action of fipronil and amitraz on the motility of Rhipicephalus sanguineus.

The motility of adult Rhipicephalus sanguineus was evaluated subsequent to treatments of amitraz, fipronil and the combination of fipronil plus amitraz against a vehicle control in a Petri dish assay using the LemnaTec Scanalyzer Imaging System. The assay was run using a fixed dilution of amitraz (0.32µg/cm(2)); serial dilutions of fipronil (1.3, 0.33, 0.08, 0.02, or 0.005µg/cm(2)); and the same serial dilutions of fipronil in combination with the fixed dilution of amitraz. Measurement of motility was made of unstimulated ticks and then after stimulation at 1, 4, 18-22, and 24h post exposure (hpe) of the Petri dishes. For the unstimulated ticks, there was no difference in motility between the amitraz treatment group and the fipronil plus amitraz treatment group at the early time points. However, these two treatment groups had significantly higher motility than the solvent control and fipronil treatment groups. The unstimulated ticks in the amitraz treatment group had significantly higher motility than the fipronil plus amitraz treatment group at the later time points. Measurements after stimulation demonstrated there was no difference in motility between the amitraz treatment group and the fipronil plus amitraz treatment group at the early time points. By 18 hpe, the fipronil plus amitraz treatment group had significantly lower motility than all other treatment groups and at 21-22 and 24 hpe the other treatment groups did not differ from the control group. The action could be divided in two phases in the combination experiment: phase 1: an early increase in motility due to amitraz is identified in both amitraz alone or fipronil plus amitraz groups; phase 2: the combination of fipronil plus amitraz caused a significantly greater reduction in motility, suggesting mortality of the ticks, compared to fipronil or amitraz alone. These results demonstrate a synergism resulting from the combination of fipronil plus amitraz.