Accuracy of tidal volume, compliance, and resistance measurements on neonatal ventilator displays: An in vitro assessment

ArticleinPediatric Critical Care Medicine 13(4):e262-8 · May 2012with59 Reads
DOI: 10.1097/PCC.0b013e3182455586 · Source: PubMed
To determine the accuracy of measures of respiratory mechanics derived from neonatal ventilators using an in vitro passive physical lung model to simulate newborn pulmonary conditions. Test lung models. Laboratory-based measurements. Three test lungs were constructed to simulate three severities of neonatal lung disease, with ranges of compliance from 0.5 to 2.0 mL/cm H2O and resistance from 25 to 150 cm H2O/(L/sec). Each ventilator was tested using 27 combinations of peak inspiratory pressure (15-25 cm H2O), positive end-expiratory pressure (5-7 cm H2O), and rate settings (20-60 B/min). Data were compared for five different ventilators across simulated lung severity as the ratio of ventilator readout to test lung reference value. A ratio of 1.0 indicated a completely unbiased result. Overall, four of the five ventilators under-read expired tidal volume by about 1%-12% across all lung conditions, whereas the VIP Bird readout ranged from -4% to +4% bias. Changes in ventilator settings had only a modest effect on mechanics readout. As peak inspiratory pressure progressed from 15 to 25 cm H2O, bias in tidal volume readout changed from +5.0% to -2.5% (p < .001) in the VIP Bird, and from -11% to -9% (p < .001) in the Draeger Babylog VN500. Between positive end-expiratory pressure levels of 5 and 7 cm H2O, tidal volume bias in the Babylog varied between -13% and -7% (p < .001). In progressing from simulated normal to severely ill lung condition, bias in compliance measurements by the Avea and SLE5000 increased from -18% to -40% whereas in the VIP Bird it remained between -17% to -13%, and in the Draeger Evita XL-neo it changed from +17% to -13% and from -8% to -16% in the Babylog. Ratio of ventilator resistance readout to reference value with progressing simulated lung condition changed from 2.0 to 1.0 for the Draeger Evita, 1.6 to 1.1 for the Babylog, 4.2 to 2.0 for the SLE, and from 11.7 to 5.6 for the VIP Bird. The Avea, by design, did not display resistances >100 cm H2O/(L/sec), but overestimated the simulated normal lung resistance of 25 cm H2O/(L/sec) by a factor of 2.5. Neonatal ventilator respiratory mechanics measurements and computation methods need further standardization to be useful in clinical settings.
    • "In the monitor trial, a newly developed resuscitation monitor is used with a built-in New Life Box Neo-RSD (NLB Neo-RSD, Advanced Life Diagnostics UG, Weener, Germany) for lung function m e a s u r e m e n t s , u s i n g a d i f f e r e n t i a l p r e s s u r e pneumotachometer with a variable orifice. Studies comparing types of RFM have been performed [5,[16][17][18][19][20] , but so far there is no study available comparing the three available RFMs for monitoring neonatal resuscitation in the delivery room. During neonatal resuscitation , the oxygen content of the inspired gas can quickly change from 21 to 100 % O 2 depending upon the infant's need. "
    [Show abstract] [Hide abstract] ABSTRACT: Conclusion: The available RFMs demonstrated clinically acceptable deviations in volume measurements, except for the Florian when changing gas conditions. What is known: •Respiratory function monitors (RFMs) are increasingly used for volume measurements during respiratory support of infants at birth. •During respiratory support at birth, gas conditions can change quickly, which can influence the volume measurements. What is new: •The available RFMs have clinically acceptable deviations when measuring the accuracy of volume measurements. •The RFM using a hot wire anemometer demonstrated clinically relevant deviations in volume measurements when changing the gas conditions. These deviations have to be taken into account when interpreting the volumes directly at birth.
    Full-text · Article · Jun 2016
    • "In more detail, the simulator has been designed to reproduce infants' breathing patterns, in both cases of controlled and assisted ventilation, and it is based on a multicompartment model composed of five autonomous units replicating the anatomy of the human lobes [6,7]. In order to ensure the adaptability of the designed simulator to the wide range of ventilation conditions that can be set during a real training session, a study of the performances of different Intensive Care Units (ICUs) neonatal ventilators was carried out as similarly reported in the literature [8]. Our study was focused on the pressure values delivered at the Pressure Inspiratory Peak (PIP) and at the end of the expiratory phase -the Positive End Expiratory Pressure (PEEP), and in particular, on the pressure values difference (ΔP). "
    [Show abstract] [Hide abstract] ABSTRACT: Background Mechanical ventilation is a therapeutic action for newborns with respiratory diseases but may have side effects. Correct equipment knowledge and training may limit human errors. We aimed to test different neonatal mechanical ventilators’ performances by an acquisition module (a commercial pressure sensor plus an isolated chamber and a dedicated software). Methods The differences (ΔP) between peak pressure values and end-expiration pressure were investigated for each ventilator. We focused on discrepancies among measured and imposed pressure data. A statistical analysis was performed. Results We investigated the measured/imposed ΔP relation. The ΔP do not reveal univocal trends related to ventilation setting parameters and the data distributions were non-Gaussian. Conclusions Measured ΔP represent a significant parameter in newborns’ ventilation, due to the typical small volumes. The investigated ventilators showed different tendencies. Therefore, a deep specific knowledge of the intensive care devices is mandatory for caregivers to correctly exploit their operating principles.
    Full-text · Article · Dec 2015
  • [Show abstract] [Hide abstract] ABSTRACT: Increased use of non-invasive forms of respiratory support such as CPAP and HFNC in premature infants has generated a need for further investigation of the pulmonary effects of such therapies. In a series of in vitro tests, we measured delivered proximal airway pressures from a HFNC system while varying both the cannula flow and the ratio of nasal prong to simulated nares diameters. Neonatal and infant sized nasal prongs (3.0 and 3.7 mm O.D.) were inserted into seven sizes of simulated nares (range: 3–7 mm I.D. from anatomical measurements in 1–3 kg infants) for nasal prong-to-nares ratios ranging from 0.43 to 1.06. The nares were connected to an active test lung set at: TV 10 ml, 60 breaths/min, Ti 0.35 sec, compliance 1.6 ml/cm H2O and airway resistance 70 cm H2O/(L/sec), simulating a 1–3 kg infant with moderately affected lungs. A Fisher & Paykel Healthcare HFNC system with integrated pressure relief valve was set to flow rates of 1–6 L/min while cannula and airway pressures and cannula and mouth leak flows were measured during simulated mouth open, partially closed and fully closed conditions. Airway pressure progressively increased with both increasing HFNC flow rate and nasal prong-to-nares ratio. At 6 L/min HFNC flow with mouth open, airway pressures remained <1.7 cm H2O for all ratios; and <10 cm H2O with mouth closed for ratios <0.9. For ratios >0.9 and 50% mouth leak, airway pressures rapidly increased to 18 cm H2O at 2 L/min HFNC flow followed by a pressure relief valve limited increase to 24 cm H2O at 6 L/min. Safe and effective use of HFNC requires careful selection of an appropriate nasal prong-to-nares ratio even with an integrated pressure relief valve. Pediatr Pulmonol. 2013; 48:506–514.
    Article · May 2013
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