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, PaCO(2) 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.

Cuff-leak test predicts the severity of postextubation acute laryngeal lesions: a preliminary study.

BACKGROUND AND OBJECTIVE: The objectives of the present study were to evaluate the relationships between the results of the cuff-leak test and the presence of laryngeal lesions; to assess whether lesions needing pharmacological treatment and surveillance can be predicted by the cuff-leak test; and to analyse the relationships between these lesions and postextubation stridor. METHODS: The present study is a preliminary, prospective, clinical investigation set in an 11-bed ICU of a university hospital. We studied 50 consecutive adult patients admitted to the ICU and mechanically ventilated for more than 72 h. All patients underwent cuff-leak test before extubation. A laryngoscopic inspection was performed after extubation to evaluate the presence and degrees of laryngeal lesions. Laryngeal lesions were classified according to a 5-degree scale (0-4); patients with clinical manifestations were pharmacologically treated and monitored. RESULTS: A threshold cuff-leak value of 0.07 l (21% of tidal volume) was determined by visual inspection of the receiver-operating characteristic plot. Patients were divided into a positive and a negative cuff-leak test group. Comparing the severity of laryngeal lesions to the cuff-leak test, a relationship between higher degrees of lesions (degrees 3-4) and the positivity of the cuff-leak test (31.3% in the positive cuff-leak test group vs. 3.8% in the negative cuff-leak test group; P = 0.023) was observed. The positive and the negative predictive values were 25 and 96.1%, respectively. Only two cases of postextubation stridor were found, one in each group. There was no correlation between the results of the cuff-leak test and the occurrence of postextubation acute respiratory difficulties. CONCLUSION: Cuff-leak test is a simple, noninvasive tool, which may be useful to exclude, in patients with prolonged intubations, the presence of laryngeal injuries needing medical treatment and close monitoring. This occurs independently of postextubation stridor.

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.

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.