Nicola Rossi

Respiratory mechanics and bronchodilator responsiveness in patients with the adult respiratory distress syndrome.

ObjectiveTo study the effects of salbutamol (a selective β2-adrenergic receptor agonist) on respiratory mechanics in patients with the adult respiratory distress syndrome (ARDS). DesignProspective study. SettingICU in a university hospital. PatientsSeven mechanically ventilated, paralyzed ARDS patients. Main Outcome MeasurementsMeasurements of respiratory system compliance, maximum, and minimum inspiratory resistance (by the end-inspiratory occlusion method during constant flow inflation) were performed at 0, 5, 10 cm H2O positive end-expiratory pressure, both before and at least 30 mins after the start of a continuous iv infusion of salbutamol (15 μg/min). Minimum inspiratory resistance represents the ohmic air flow resistance, while maximum inspiratory resistance includes minimum inspiratory resistance plus the effective additional resistance due to stress adaptation and to time constant inhomogeneities. Air flow was measured at the airway connector and tracheal pressure near the central end of the artificial airway. ResultsMaximum inspiratory resistance, minimum inspiratory resistance, and additional resistance were higher than the values reported for normal anesthetized subjects. On average, salbutamol caused a decrease in maximum and minimum inspiratory resistances (from 6.48 ± 2.56 to 4.67 ± 1.74 and from 4.06 ± 2.12 to 2.07 ± 0.95 cm H2O/L/sec, respectively). Positive end-expiratory pressure increased additional resistance, whereas it decreased minimum inspiratory resistance. No interaction was found between positive end-expiratory pressure and salbutamol. Respiratory system compliance was not significantly affected by salbutamol nor positive end-expiratory pressure. ConclusionsIn ARDS patients, salbutamol decreases the abnormally high airway resistance by reducing minimum resistance, but has effect on the effective additional resistance. (Crit Care Med 1993: 21:78–83)

Design and Development of Ultrathin-walled, Nonkinking Endotracheal Tubes of a New “No-pressure” Laryngeal Seal Design: A Preliminary Report

BackgroundEndotracheal tubes (ETTs) of conventional design and manufacture greatly increase the air-flow resistance of the upper airways. This increase in upper-airway resistance can lead to a significant increase in the work of breathing and may necessitate the use of assisted mechanical ventilation. Current ETTs are relatively stiff and contribute greatly to patient discomfort. The inflatable cuffs now mounted onto the ETTs function well in short-term use but impart significant morbidity when used over longer periods. These issues were addressed by the designing of a low-resistance ETT. MethodsUsing new techniques, we developed ultrathin-walled, wire reinforced ETTs of conventional configuration and ETTs the oropharyngeal-section diameter of which was a few millimeters larger than the diameter of the tracheal section. The wall thickness was a constant 0.20 mm. The wire reinforcement was stainless steel flat wire or superelastic nickel-titanium alloy. The superelastic nickel-titanium alloy reinforcement made those ETTs crush-proof; after forceful manual compression, recovery was complete. To obtain a seal with the upper airways, we first shaped a short section of the oropharyngeal section of the ETT from round to oval (or egg-shaped) to conform better to the larynx. We then attached to this segment numerous soft, pliable, 0.025–0.075-mm-thick rings of polyurethane to occlude voids for potential air leaks from within the larynx. ResultsIn vitro pressure-flow studies showed a decrease by as much as four- or fivefold in air-flow resistance in the adult ETT range, effectively increasing the internal diameter by 2.3–3.7 mm, compared with conventional ETTs of the same outside diameter. In vivo studies for 24 h in sheep showed no air leaks at airway pressures to 30 cmH2O and minimal leak at greater pressures. The gross appearance of the trachea was normal. ConclusionsAlthough the new tubes appear to offer advantages to those currently used, testing in humans is required to assess the clinical utility of the tube-cuff design.

Relationship Between Viremia and Specific Organ Damage in Ebola Patients: A Cohort Study

Background Pathogenesis of Ebola virus disease remains poorly understood. We used concomitant determination of routine laboratory biomarkers and Ebola viremia to explore the potential role of viral replication in specific organ damage. Methods We recruited patients with detectable Ebola viremia admitted to the EMERGENCY Organizzazione Non Governativa Organizzazione Non Lucrativa di Utilità Sociale (ONG ONLUS) Ebola Treatment Center in Sierra Leone. Repeated measure of Ebola viremia, alanine aminotransferase (ALT), aspartate aminotransferase (AST), bilirubin, creatine phosphokinase (CPK), lactate dehydrogenase (LDH), activated prothrombin time (aPTT), international normalized ratio (INR), creatinine, and blood urea nitrogen (BUN) were recorded. Patients were followed up from admission until death or discharge. Results One hundred patients (49 survivors and 51 nonsurvivors) were included in the analysis. Unadjusted analysis to compare survivors and nonsurvivors provided evidence that all biomarkers were significantly above the normal range and that the extent of these abnormalities was generally higher in nonsurvivors than in survivors. Multivariable mixed-effects models provided strong evidence for a biological gradient (suggestive of a direct role in organ damage) between the viremia levels and either ALT, AST, CPK LDH, aPTT, and INR. In contrast, no direct linear association was found between viremia and either creatinine, BUN, or bilirubin. Conclusions This study provides evidence to support that Ebola virus may have a direct role in muscular damage and imbalance of the coagulation system. We did not find strong evidence suggestive of a direct role of Ebola virus in kidney damage. The role of the virus in liver damage remains unclear, but our evidence suggests that acute severe liver injury is not a typical feature of Ebola virus disease.