Alberto Peratoner

Intrapulmonary percussive ventilation improves the outcome of patients with acute exacerbation of chronic obstructive pulmonary disease using a helmet.

Objective:To evaluate the effect of intrapulmonary percussive ventilation (IPV) by mouthpiece during noninvasive positive-pressure ventilation with helmet in patients with exacerbation of chronic obstructive pulmonary disease (COPD). Design:Randomized clinical trial. Setting:General intensive care unit, university hospital. Patients:Forty patients with exacerbation of COPD ventilated with noninvasive positive-pressure ventilation by helmet were randomized to two different mucus clearance strategies: IPV (IPV group) vs. respiratory physiotherapy (Phys group). As historical control group, 40 patients receiving noninvasive positive pressure and ventilated by face mask treated with respiratory physiotherapy were studied. Interventions:Two daily sessions of IPV (IPV group) or conventional respiratory physiotherapy (Phys group). Measurements and Main Results:Physiologic variables were measured at entry in the intensive care unit, before and after the first session of IPV, and at discharge from the intensive care unit. Outcome variables (need for intubation, ventilatory assistance, length of intensive care unit stay, and complications) were also measured. All physiologic variables improved after IPV. At discharge from the intensive care unit, Paco2 was lower in the IPV group compared with the Phys and control groups (mean ± sd, 58 ± 5.4 vs. 64 ± 5.2 mm Hg, 67.4 ± 4.2 mm Hg, p < .01). Pao2/Fio2 was higher in IPV (274 ± 15) than the other groups (Phys, 218 ± 34; control, 237 ± 20; p < .01). In the IPV group, time of noninvasive ventilation (hrs) (median, 25th–75th percentile: 61, 60–71) and length of stay in the intensive care unit (days) (7, 6–8) were lower than other groups (Phys, 89, 82–96; control, 87, 75–91; p < .01; and Phys, 9, 8–9; control, 10, 9–11; p < .01). Conclusions:IPV treatment was feasible for all patients. Noninvasive positive-pressure ventilation by helmet associated with IPV reduces the duration of ventilatory treatment and intensive care unit stay and improves gas exchange at discharge from intensive care unit in patients with severe exacerbation of COPD.

Comparison of noninvasive ventilation by sequential use of mask and helmet versus mask in acute exacerbation of chronic obstructive pulmonary disease: a preliminary study.

Background:Noninvasive positive pressure ventilation (NPPV) using a face mask is the ventilatory mode of choice in selected patients experiencing acute exacerbation of chronic obstructive pulmonary disease (COPD). A high incidence of intolerance limits the use of this approach. Objective: To evaluate the sequential use of mask and helmet during NPPV in patients with severe exacerbation of COPD in order to reduce the intolerance to these devices. Methods: Fifty-three patients ventilated for the first 2 h with NPPV by mask were studied. If gas exchange and clinical status improved, they were randomized to continue on NPPV by mask or helmet.Physiological parameters were measured at admission, after the first 2 h on NPPV by mask, 4 h after randomization and at discharge. Need for intubation, ventilatory assistance, length of stay (LOS) and complications were recorded. Results: After the first 2 h of NPPV, gas exchange and clinical parameters improved in 40 patients. Four hours after randomization, PaCO2 was lower in the mask group than in the helmet group. Nine patients in the mask group and 2 in the helmet group failed NPPV, 8 and 1, respectively, owing to intolerance. Time of noninvasive ventilation and LOS were lower in the mask than in the helmet group. Conclusions: In patients with acute exacerbation of COPD and undergoing NPPV, the sequential use of a mask and helmet diminished the incidence of failure. Under the present experimental conditions, the use of a helmet increased LOS and the duration of artificial ventilation.

Early short-term application of high-frequency percussive ventilation improves gas exchange in hypoxemic patients.

Background: Hypoxemia in acute lung injury/acute respiratory distress syndrome (ALI/ARDS) patients represents a common finding in the intensive care unit (ICU) and frequently does not respond to standard ventilatory techniques. Objective: To study whether the early short-term application of high-frequency percussive ventilation (HFPV) can improve gas exchange in hypoxemic patients with ALI/ARDS or many other conditions in comparison to conventional ventilation (CV) using the same mean airway pressure (P_aw), representing the main determinant of oxygenation and hemodynamics, irrespective of the mode of ventilation. Methods: Thirty-five patients not responding to CV were studied. During the first 12 h after admission to the ICU the patients underwent CV. Thereafter HFPV was applied for 12 h with P_aw kept constant. They were then returned to CV. Gas exchange was measured at: 12 h after admission, every 4 h during the HFPV trial, 1 h after the end of HFPV, and 12 h after HFPV. Thirty-five matched patients ventilated with CV served as the control group (CTRL). Results: Pa<smlcap>o</smlcap>₂/Fi<smlcap>o</smlcap>₂ and the arterial alveolar ratio (a/A P<smlcap>o</smlcap>₂) increased during HFPV treatment and a Pa<smlcap>o</smlcap>₂/Fi<smlcap>o</smlcap>₂ steady state was reached during the last 12 h of CV, whereas both did not change in CTRL. Pa<smlcap>c</smlcap><smlcap>o</smlcap>₂ decreased during the first 4 h of HFPV, but thereafter it remained unaltered; Pa<smlcap>c</smlcap><smlcap>o</smlcap>₂ did not vary in CTRL. Respiratory system compliance increased after HFPV. Conclusions: HFPV improved gas exchange in patients who did not respond to conventional treatment. This improvement remained unaltered until 12 h after the end of HFPV.

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 τ 2) 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 ruslts 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 τ 2, 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 τ 2, 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.

Static and Dynamic Intrinsic PEEP and Respiratory Mechanics in Mechanically Ventilated COPD Patients

In 1982, Pepe and Marini [1] pointed out the clinical importance of dynamic increase in end-expiratory lung volume and positive end-expiratory alveolar pressure in mechanically ventilated patients with airflow obstruction. This end-expiratory pressure was termed “occult, auto or intrinsic PEEP” (PEEPi) and is due to the positive end-expiratory elastic recoil pressure of the total respiratory system consequent to incomplete lung emptying. In patients with severe airflow obstruction, because the rate of the lung emptying is slow relative to the available expiratory duration, the expiration is interrupted by the subsequent breath before the relaxation volume of the respiratory system (Vr) is reached. The increase in end expiratory lung volume above Vr is termed dynamic pulmonary hyperinflation. Dynamic hyperinflation and PEEPi were detected not only in ventilated patients with airway obstruction but also in ventilated patients with other disorders [2–4] and in all ventilatory conditions in which a short expiratory time is used, as inverse ratio ventilation (5, 6].