High-frequency percussive ventilation.
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High-Frequency Ventilation↗
Biomedical subjects
Umberto Lucangelo
Publications and source records attributed to Umberto Lucangelo.
Respiratory mechanics derived from signals in the ventilator circuit.
The aim of this article is to identify and interpret the data provided by modern ventilators that provide the greatest clinical help in evaluating respiratory mechanics during mechanical ventilation. In intensive care, respiratory mechanics can be assessed in dynamic conditions (no flow-interruption) or static conditions (occlusion techniques) to record compliance and resistance and to monitor pressure, flow, and volume. Real-time visualization of the pressure curve is crucial for monitoring during volume-controlled ventilation, in which pressure is the dependent variable. Analysis of the pressure curve has little clinical utility during pressure-controlled ventilation, in which the dependent variable is the flow waveform, which varies according to changes in the mechanics of the respiratory system. Pressure-volume loops and flow-volume loops provide useful information on the dynamic trends of the respiratory system compliance and resistance, respectively. Modern ventilators provide complete monitoring of respiratory system mechanics, which is our guideline for optimizing ventilatory support and avoiding complications associated with mechanical ventilation.
Airway Resistance↗
Measurement of air trapping, intrinsic positive end-expiratory pressure, and dynamic hyperinflation in mechanically ventilated patients.
Severe airflow obstruction is a common cause of acute respiratory failure. Dynamic hyperinflation affects tidal ventilation, increases airways resistance, and causes intrinsic positive end-expiratory pressure (auto-PEEP). Most patients with asthma and chronic obstructive pulmonary disease have dynamic hyperinflation and auto-PEEP during mechanical ventilation, which can cause hemodynamic compromise and barotrauma. Auto-PEEP can be identified in passively breathing patients by observation of real-time ventilator flow and pressure graphics. In spontaneously breathing patients, auto-PEEP is measured by simultaneous recordings of esophageal and flow waveforms. The ventilatory pattern should be directed toward minimizing dynamic hyperinflation and auto-PEEP by using small tidal volume and preserving expiratory time. With a spontaneously breathing patient, to reduce the work of breathing and improve patient-ventilator interaction, it is crucial to set an adequate inspiratory flow, inspiratory time, trigger sensitivity, and ventilator-applied PEEP. Ventilator graphics are invaluable for monitoring and treatment decisions at the bedside.
Airway Obstruction↗
Sildenafil in pulmonary arterial hypertension.
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Animals↗
Anticipating events of in-hospital cardiac arrest.
STUDY OBJECTIVES: To determine whether in-hospital cardiac arrests occurring in regular wards are preceded by some event(s), and the diagnostic and therapeutic measures adopted. METHODS: From 1 May 1999 to 31 December 2001, events occurring in the 6 h preceding cardiac arrest were reviewed by checking the medical and nurse records and interviewing the attending staff. Exclusion criteria were (a) location in the Coronary Care Unit, the Intensive Care Unit, the Emergency Department and the operating rooms; (b) the presence of rapidly fatal disease; (c) the lack of adequate documentation. RESULTS: Overall, 263 cardiac arrests occurred in the period under consideration. A total of 148 patients (61 women, 87 men, aged 74.3+/-1.2 years) fulfilled the entry criteria. Anticipating events were reported in 128 patients (86.4%). These included alterations in consciousness, cardiac arrhythmias, dyspnoea and chest pain. The restoration of cardiac rhythm was obtained in 23 patients (15.5%). Eight (5.4%) survived without major neurological sequelae. Survivors were significantly younger than non-survivors (survivors 44.3+/-6.8 years; non-survivors 76.7+/-2.1 years; P<0.005). In a substantial number of cases, ranging from 23 to 81%, according to the anticipating event, no diagnostic investigations were performed. CONCLUSION: Most in-hospital cardiac arrests are preceded by events that often go overlooked and whose correct interpretation could be associated with a reduced mortality rate.
Adult↗
Sigh: tool to determine the respiratory viscoelastic properties.
OBJECTIVE: In mechanically ventilated patients a high fraction of the pressure can be dissipated to overcome the viscoelastic components of the respiratory system. Recently it was demonstrated that sigh improved oxygenation in mechanically ventilated ARDS patients. We evaluated if, in acute lung injury (ALI) patients, the sigh can be used to measure the respiratory viscoelastic properties. METHODS: Ten consecutive normal subjects undergoing general anaesthesia for minor abdominal surgery and ten ALI patients admitted to the ICU, were studied. Three sighs were administered every minute during the measurement period. The viscoelastic constants (E2, R2 and tau2) were determined by (i) a series of end-inflation airway occlusions (multiple breath method, MBM) and (ii) fitting the time course of the slow decay in pressure during end inspiratory pause of the sigh (sigh method, SM). The results were compared by means of the limits of agreement as modified for small sample sizes. RESULTS: Viscoelastic parameters were similar to those obtained in other studies. In normal subjects the mean differences (+/- SEM) of tau2, R2, and E2 given by the SM and the MBM were 0 +/- 0.04 s, 0.37 +/- 0.20 cmH2O L(-1) s, and 0.21 +/- 0.26 cmH2O L(-1), respectively. The mean differences (+/- SEM) of tau2, R2, and E2 in ALI patients were 0.02 +/- 0.02 s, 0.45 +/- 0.31 cmH2O L(-1) s, 0.34 +/- 0.36 cmH2O L(-1), respectively. No lack of agreement could be detected between the two methods in all variables in normal subjects and ALI patients. CONCLUSIONS: The long inflation time characteristic of the sigh allowed the determination of the viscoelastic constants by means of a simpler and faster method. Moreover it does not require very small tidal volumes, which can increase reabsorption atelectasis in ALI patients and can improve alveolar recruitment and oxygenation in these patients.
Anesthesia, General↗