Carbon dioxide rebreathing in non-invasive ventilation. Analysis of masks, expiratory ports and ventilatory modes. Monaldi Arch Chest Dis


Carbon dioxide (CO2) rebreathing is a complication of non-invasive ventilation (NIV). Our objectives were to evaluate the ability of masks with exhaust vents (EV) to avoid rebreathing while using positive pressure (PP) NIV with different levels of expiratory pressure (EPAP). Concerning volume-cycled NIV, we aimed to determine whether cylindrical spacers located in the circuit generate rebreathing.
5 healthy volunteers were evaluated. Bi-level PP was used with 3 nasal and 2 facial masks with and without EV. Spacers of increasing volume attached to nasal hermetic masks were evaluated with volume NIV. Inspired CO2 fraction was analyzed.
Rebreathing was zero with all nasal masks and EPAP levels. Using facial masks 1 volunteer showed rebreathing. There was no rebreathing while using all the spacers.
In healthy volunteers, nasal and facial masks with EV prevent rebreathing. In addition, the use of spacers did not generate this undesirable phenomenon.

  • [Show abstract] [Hide abstract]
    ABSTRACT: Several factors in noninvasive positive pressure ventilation (NIPPV) have proved to be potential causes of failure when this kind of mechanical respiratory assistance is used in patients who suffer from acute (ARF) or chronic (CRF) respiratory failure [1–3]. One such factor is carbon dioxide (CO2) rebreathing [1–4]. This phenomenon consists of rebreathing part of the CO2 expired by the patient during the ventilatory cycle as a result of an accumulation of this gas in the mask or the circuit. Such rebreathing takes place mainly in single-limb circuits (inspiration and expiration into the same tube). Besides the use of such a circuit, there are technical circumstances that play an active role in the presence or elimination of expired CO2: the ventilatory mode [4, 5], type of mask and expiratory port [6–12], as well as the level of positive end-expiratory pressure (PEEP) used [4, 10, 11]. Since 1995, when Ferguson and his collaborators first described such a phenomenon, little research has been done on this issue. The development of technological innovations, mainly in interfaces, has restricted the potential clinical implications of this deleterious phenomenon. Likewise, research works conducted so far have not confirmed whether CO2 rebreathing does have a significant influence on patients’ clinical evolution or is just a potentially, but rarely, harmful phenomenon.
    Noninvasive Mechanical Ventilation, 01/2010: pages 87-92; , ISBN: 978-3-642-11364-2
  • [Show abstract] [Hide abstract]
    ABSTRACT: Noninvasive positive pressure ventilation (NPPV) refers to the delivery of mechanical ventilation to the lungs using techniques that do not require an endotracheal intubation. In the past decade NPPV has gained wide acceptance and is now used more frequently after development of portable ventilators, new modes of ventilation and other equipments. This article will provide a comprehensive overview of the current stage of NPPV in acute and chronic settings. It will appraise the evidence based efficacy of NPPV in patients who presented with acute exacerbation of chronic hypercapneic respiratory failure. The main focus of discussion in this article is to provide detailed knowledge regarding choosing appropriate ventilators and interfaces, selecting appropriate patients and initiating NPPV and their weaning.
    Journal of the Pakistan Medical Association 06/2011; 61(6):592-7. · 0.41 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Background: Many types of interfaces with intentional leaks exist for Non Invasive Ventilation. The purpose of intentional leaks is to remove CO2 from the interface, however the calibration does not allow a sufficiently large flow and rebreathing of CO2 can occur. The aim of this study was to compare the CO2 rinsing capacities of three new generation oronasal masks with intentional leaks (A: Quattro®, [Resmed]; B: Amara® [Respironics]; C: Forma® [Fisher&Paykel]) in healthy subjects. Methods: Seventeen healthy volunteers were included in this prospective cross-sectional, randomized, double-blinded trial. Each subject underwent ventilation with a home ventilator (IPAP: 14 cmH2O; EPAP: 4 cmH2O) with each mask consecutively. Transcutaneous capnography (PtcCO2) recordings were carried out throughout the trial and ventilator data (tidal volume, respiratory rate, minute ventilation and unintentional leaks) were also analyzed. Mask comfort was assessed using a visual analog scale (0 to 10). Results: The results showed no differences in PtcCO2 between masks (P=0.82). There were no significant differences in respiratory parameters (tidal volume, P=0.79; respiratory rate, P=0.65; minute ventilation, P=0.12) between masks. The rate of unintentional leaks were significantly lower for Mask A (P=0.016). Subjects rated Mask A and Mask C as more comfortable than Mask B (P=0.041). Conclusion: There was no effect of mask on PtcCO2 in healthy subjects. The mask with the highest comfort rating had not the lowest rate of unintentional leaks.
    Minerva anestesiologica 10/2014; 81(5). · 2.13 Impact Factor
Show more