Detection of Simulated Pediatric Breathing by CPAP/NIV Devices

BACKGROUND

Home CPAP and noninvasive ventilation (NIV) are increasingly used in children. An appropriate choice of the CPAP/NIV device, according to the manufacturer recommendations, should guarantee accurate data collection software. However, not all devices display accurate patient data. We hypothesized that the detection of patient breathing may be expressed as a minimal tidal volume (V_Tmin ) rather than a minimal weight. The aim of the study was to estimate the V_Tmin detected by home ventilators when set on CPAP.

METHODS

Twelve level I-III devices were analyzed using a bench test. Pediatric profiles were simulated with increasing V_T values to determine the V_Tmin that the ventilator may detect. The duration of CPAP use and the presence/absence of waveform tracings on the built-in software were also gathered.

RESULTS

V_Tmin varied according to the device, ranging from 16-84 mL, independent of level category. The duration of CPAP use was underestimated in all level I devices, which were either not able to display any waveform or only intermittently, until V_Tmin was reached. The duration of CPAP use was overestimated for the level II and III devices, with the display of different waveforms according to the device as soon as the device was switched on.

CONCLUSIONS

Based on the V_Tmin detected, some level I and II devices may be suitable for infants. A careful testing of the device should be done at CPAP initiation, with a review of data generated from ventilator software.

Accuracy of tidal volume delivered by home mechanical ventilation during mouthpiece ventilation: A bench evaluation

The aim of our study was to evaluate efficacy and reliability of currently available ventilators for mouthpiece ventilation (MPV). Five life-support home ventilators were assessed in a bench test using different settings simulating the specificities of MPV, such as intermittent circuit disconnection and presence of continuous leaks. The intermittent disconnection of the circuit caused relevant swings in the delivered tidal volume ( V_T), showing a V_T overshoot during the disconnection periods and a V_T decrease when the interface was reconnected to the test lung. The five ventilators showed substantial differences in the number of respiratory cycles necessary to reach a stable V_T in the volume-controlled setting, ranging from 1.3 ± 0.6 to 7.3 ± 1.2 cycles. These differences were less accentuated in the volume-assisted setting (MPV-dedicated mode, when available). Our data show large differences in the capacity of the different ventilators to deal with the rapidly changing respiratory load features that characterize MPV, which can be further accentuated according to the used ventilator setting. The dedicated MPV modes allow improvement in the performance of ventilators only in some defined situations. This has practical consequences for the choice of the ventilator to be used for MPV in a specific patient.

Evaluation of ventilators for mouthpiece ventilation in neuromuscular disease

BACKGROUND

Daytime mouthpiece ventilation is a useful adjunct to nocturnal noninvasive ventilation (NIV) in patients with neuromuscular disease. The aims of the study were to analyze the practice of mouthpiece ventilation and to evaluate the performance of ventilators for mouthpiece ventilation.

METHODS

Practice of mouthpiece ventilation was assessed by a questionnaire, and the performance of 6 home ventilators with mouthpiece ventilation was assessed in a bench test using 24 different conditions per ventilator: 3 mouthpieces, a child and an adult patient profile, and 4 ventilatory modes.

RESULTS

Questionnaires were obtained from 30 subjects (mean age 33 ± 11 y) using NIV for 12 ± 7 y. Fifteen subjects used NIV for > 20 h/day, and 11 were totally ventilator-dependent. The subject-reported benefits of mouthpiece ventilation were a reduction in dyspnea (73%) and fatigue (93%) and an improvement in speech (43%) and eating (27%). The bench study showed that none of the ventilators, even those with mouthpiece ventilation software, were able to deliver mouthpiece ventilation without alarms and/or autotriggering in each condition. Alarms and/or ineffective triggering or autotriggering were observed in 135 of the 198 conditions. The occurrence of alarms was more common with a large mouthpiece without a filter compared to a small mouthpiece with a filter (P < .001), but it was not related to the patient profile, the ventilatory mode, or the type of ventilator.

CONCLUSIONS

Subjects are satisfied with mouthpiece ventilation. Alarms are common with home ventilators, although less common in those with mouthpiece ventilation software. Improvements in home ventilators are needed to facilitate the expansion of mouthpiece ventilation.

Battery life of portable home ventilators: effects of ventilator settings

BACKGROUND

The battery life (BL) of portable home ventilator batteries is reported by manufacturers. The aim of this study was to evaluate the effects of ventilator mode, breathing frequency, PEEP, and leaks on the BL of 5 commercially available portable ventilators.

METHODS

The effects of the ventilator mode (volume controlled-continuous mandatory ventilation [VC-CMV] vs pressure support ventilation [PSV]), PEEP 5 cm H2O, breathing frequency (10, 15, and 20 breaths/min), and leaks during both volume-targeted ventilation and PSV on the BL of 5 ventilators (Elisée 150, Monnal T50, PB560, Vivo 50, and Trilogy 100) were evaluated. Each ventilator was ventilated with a test lung at a tidal volume of 700 ml and an inspiratory time of 1.2 s in the absence of leaks.

RESULTS

Switching from PSV to VC-CMV or the addition of PEEP did not significantly change ventilator BL. The increase in breathing frequency from 10 to 20 breaths/min decreased the BL by 18 ± 11% (P = .005). Leaks were associated with an increase in BL during the VC-CMV mode (18 ± 20%, P = .04) but a decrease in BL during the PSV mode (-13 ± 15%, P = .04).

CONCLUSIONS

The BL of home ventilators depends on the ventilator settings. BL is not affected by the ventilator mode (VC-CMV or PSV) or the addition of PEEP. BL decreases with an increase in breathing frequency and during leaks with a PSV mode, whereas leaks increase the duration of ventilator BL during VC-CMV.