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Objective: To explore the user-friendliness and ergonomics of seven new generation intensive care ventilators. Design: Prospective task-performing study. Setting: Intensive care research laboratory, university hospital. Methods: Ten physicians experienced in mechanical ventilation, but without prior knowledge of the ventilators, were asked to perform eight specific tasks [turning the ventilator on; recognizing mode and parameters; recognizing and setting alarms; mode change; finding and activating the pre-oxygenation function; pressure support setting; stand-by; finding and activating non-invasive ventilation (NIV) mode]. The time needed for each task was compared to a reference time (by trained physiotherapist familiar with the devices). A time >180s was considered a task failure. Results: For each of the tests on the ventilators, all physicians' times were significantly higher than the reference time (P

Objective: To test the feasibility of applying noninvasive ventilation (NIV) using aprototype algorithm implemented in abilevel ventilation device designed to adjust pressure support (PS) to maintain aclinician-set alveolar ventilation in patients with acute respiratory failure after initial stabilization. Design and setting: Prospective crossover interventional study in an intensive care unit, university hospital. Patients: 19 patients receiving NIV for acute hypercapnic respiratory failure (13 men, 6 women; mean age 70 ± 11 years). Methods: The same bilevel ventilator was used with manually adjusted PS and with the automated algorithm (autoPS), set to maintain the same alveolar ventilation as in PS. Sequence (measurements at end of each period): (a) prior to initiating NIV (baseline 1); (b) 45 min with manually set PS; (c) 60 min without NIV; (d) 45 min with autoPS; (e) 60 min without NIV; (f) 45 min with manually set PS. Results: The magnitude of decrease in PaCO2 and increase in pH with autoPS was comparable to that of conventional PS, with the same alveolar ventilation and level of PS. No technical problem occurred in autoPS mode, and no NIV trial had to be discontinued because of patient discomfort. Conclusions: These results suggest that the alveolar ventilation based automatic control of PS during NIV with abilevel device is feasible and leads to beneficial effects in patients with acute respiratory failure comparable to those of manually set PS. Further studies should now explore the potential of this system over longer periods in patients with acute and chronic respiratory failure

Objective: To evaluate the feasibility of using aknowledge-based system designed to automatically titrate pressure support (PS) to maintain the patient in a"respiratory comfort zone” during noninvasive ventilation (NIV) in patients with acute respiratory failure. Design and setting: Prospective crossover interventional study in an intensive care unit of auniversity hospital. Patients: Twenty patients. Interventions: After initial NIV setting and startup in conventional PS by the chest physiotherapist NIV was continued for 45 min with the automated PS activated. Measurements and results: During automated PS minute-volume was maintained constant while respiratory rate decreased significantly from its pre-NIV value (20 ± 3 vs. 25 ± 3 bpm). There was atrend towards aprogressive lowering of dyspnea. In hypercapnic patients PaCO2 decreased significantly from 61 ± 9 to 51 ± 2 mmHg, and pH increased significantly from 7.31 ± 0.05 to 7.35 ± 0.03. Automated PS was well tolerated. Two system malfunctions occurred prompting physiotherapist intervention. Conclusions: The results of this feasibility study suggest that the system can be used during NIV in patients with acute respiratory failure. Further studies should now determine whether it can improve patient-ventilator interaction and reduce caregiver workload

To determine the prevalence of patient-ventilator asynchrony in patients receiving non-invasive ventilation (NIV) for acute respiratory failure. Prospective multicenter observation study. Intensive care units in three university hospitals. Patients consecutively admitted to ICU were included. NIV, performed with an ICU ventilator, was set by the clinician. Airway pressure, flow, and surface diaphragmatic electromyography were recorded continuously for 30 min. Asynchrony events and the asynchrony index (AI) were determined from visual inspection of the recordings and clinical observation. A total of 60 patients were included, 55% of whom were hypercapnic. Auto-triggering was present in 8 (13%) patients, double triggering in 9 (15%), ineffective breaths in 8 (13%), premature cycling 7 (12%) and late cycling in 14 (23%). An AI > 10%, indicating severe asynchrony, was present in 26 patients (43%), whose median (25-75 IQR) AI was 26 (15-54%). A significant correlation was found between the magnitude of leaks and the number of ineffective breaths and severity of delayed cycling. Multivariate analysis indicated that the level of pressure support and the magnitude of leaks were weakly, albeit significantly, associated with an AI > 10%. Patient comfort scale was higher in pts with an AI < 10%. Patient-ventilator asynchrony is common in patients receiving NIV for acute respiratory failure. Our results suggest that leaks play a major role in generating patient-ventilator asynchrony and discomfort, and point the way to further research to determine if ventilator functions designed to cope with leaks can reduce asynchrony in the clinical setting.

To compare triggering, pressurization, and cycling of the home ventilator VPAP II with those of three ICU ventilators (Evita 4, Galileo, and Servo 300).Two-compartment lung model study in a research laboratory, university hospital.One compartment was driven by an ICU ventilator to mimic "patient" inspiratory effort, while the other was connected to the tested ventilator. Pressure support of 10, 15, 20, and 25 cmH2O, and inspiratory efforts of 5, 10, 15, 20, and 25 cmH2O (inspiratory time 1 s) were used in normal, obstructive, and restrictive conditions. Triggering delay (Td), triggering workload, pressurization at 300 and 500 ms, and difference between the "patient's" inspiratory time and that of the ventilator were analyzed.No difference was noted in triggering workload between VPAP II, Evita 4, and Galileo while Servo 300 had a lower value. Pressurization at 300 ms on Evita 4 and Servo 300 reached 75% of the ideal value, on Galileo 35%, and on VPAP II 45%. Pressurization at 500 ms on Evita 4 and Servo 300 reached 85% of the ideal value, on Galileo 50%, and on VPAP II 55%. Cycling was delayed in obstructive conditions and premature in restrictive conditions with each of the devices.The VPAP II performed as well as one ICU ventilator and less well than two. Home devices for noninvasive ventilation in acute respiratory failure outside the ICU could prove attractive as they are smaller, less costly, and easier to use than ICU machines.