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The Mapleson D continuous positive airway pressure system: a novel indication for the Mapleson circuit?

Palomero Rodríguez, Miguel Angel; Carretero, Pascual Sanabria; Báez, Yolanda Laporta; Alvarez, Felipe Villar

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European Journal of Anaesthesiology: February 2009 - Volume 26 - Issue 2 - p 177-179
doi: 10.1097/EJA.0b013e32831a45f8
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Noninvasive positive airway pressure ventilation has been described as safe and effective in infants with mild-to-moderate hypoxaemic respiratory insufficiency, upper airway obstruction and postextubation respiratory distress [1–3]; however, more evidence is necessary to define the mode of ventilation support to be used for specific cases, the adequate type of interface and the length of use and weaning [1,3]. Over the past 3 years, we have used a flow-inflating bag circuit with a nasotracheal or nasopharyngeal tube as an interface to deliver effective continuous positive airway pressure (CPAP) support in about 120 infants (‘Mapleson D CPAP system’) with acute respiratory insufficiency, for weaning of mechanical ventilation and to provide CPAP outside the intensive care unit. The Mapleson D CPAP system was made by a Mapleson D system (Intersurgical, Wokingham, UK) with a 0.5 or 1 l reservoir bag and 20 mm corrugated tubing that was connected to a lubricated uncuffed endotracheal number 3.5 to number 5.0 Portex blue line uncuffed endotracheal tube (Smiths Medical, London, UK), as a nasopharyngeal or nasotracheal airway. Airway pressure was measured at the proximal end of the system with a manometer (Vygon, Ecouen, France) (Fig. 1). Fresh gas was enriched with a Siemens O2–air mixer (Siemens-Elema, Goteborg, Sweden) and was warmed and humidified using a Bennett Cascade (Bennett, London, UK) humidifier. We used a fresh gas flow rate of at least two to three times total ventilation to prevent rebreathing of CO2[4]. Here we present the cases of three patients as examples of different clinical problems to show the versatility of this simple and effective procedure.

Fig. 1
Fig. 1

A 3-year-old patient with Morquio syndrome and obstructive sleep apnoea was admitted to the radiology room to undergo a computed tomography (CT) scan. After the application of sevoflurane (inspired fraction 3%) with nasal prongs (3 l/min), he commenced with stridor, resulting in progressive dyspnoea and an SpO2 of 84%. The Mapleson D CPAP system with a nasopharyngeal tube as interface (6 cmH2O CPAP level; FiO2 0.50) was applied and 2 min later SpO2 increased to 96%. Normal breathing was maintained during the rest of the procedure.

A 28-month-old child weighing 12 kg was admitted to our paediatric intensive care unit (PICU) after having surgery for preductal aortic coarctation associated with interventricular communication. Six hours later, a chest radiograph showed changes consistent with acute pulmonary oedema. Her arterial blood gases on volume controlled mechanical ventilation [tidal volume 15 ml, respiratory rate 22 breaths min−1, positive end-expiratory pressure (PEEP) 5 cmH2O] were pH 7.36, PaCO2 65 mmHg, and PaO2 56 (FiO2 0.6). Twenty-four hours after intervention (tidal volume 20 ml, respiratory rate 24 breaths min−1, PEEP 5 cmH2O), her gases improved [pH 7.42, PaCO2 53 mmHg, and PaO2 72 (FiO2 0.6)] and, prior to discontinuing her sedation, the orotracheal tube was replaced by a nasotracheal one to facilitate tracheal extubation. Two hours later, with the patient breathing spontaneously through the nasotracheal tube with the Mapleson D CPAP system (5 cmH2O CPAP level, FiO2 0.35, spontaneous respiratory rate 24 breaths min−1), her arterial blood gases were pH 7.46, PaCO2 53 mmHg, and PaO2 107 and she was extubated to nasopharyngeal CPAP (7 cmH2O CPAP level, FiO2 0.50, and spontaneous respiratory rate 24 breaths min−1). The patient made a steady recovery, tolerating the Mapleson D CPAP system intermittently for 36 h and was discharged from PICU 4 days later.

A 12-year-old boy was admitted to our PICU with hypoxaemic respiratory failure. He was restless and clinically deteriorating, with an SpO2 of 84%. A chest radiograph showed a right lower lobe pneumonia. His temperature was 39°C. Antibiotics, chest physiotherapy, and a nasopharyngeal airway Mapleson D CPAP system (8 cmH2O CPAP level, FiO2 0.60, and spontaneous respiratory rate 22 breaths min−1) were commenced. Two hours later, his oxygen saturation was 93%. The application of CPAP was continued constantly for 72 h with good tolerance, requiring minimum doses of sedation with midazolam and with a full recovery after a total of 7 days.

One of the advantages of the Mapleson D CPAP system is the use of a nasopharyngeal tube as an interface. In paediatric patients, problems with mask leaks and an inability to attain the adjusted peak inspiratory pressure are common with nasal and facial masks in the acute setting. In addition, the volume of the mask itself leads to increased dead space, especially in young children, thus limiting the benefit of noninvasive mechanical ventilation [2,3]. Moreover, children's natural fear of any device that covers their nose or mouth represents a major limitation of using face masks [1,3]. The use of a nasopharyngeal tube as an interface avoids discomfort and facial bruising as well as the increase in dead space secondary to the use of nasal or face masks. Potential disadvantages of the nasopharyngeal tube are nasal trauma and leaks through an open mouth, which we minimized using a dummy. Chavez et al.[5] described the utilization of a Mapleson C circuit as a spontaneous breathing trial to predict successful extubation. According to these authors, an important advantage of this method over the T-piece was that it could readily provide CPAP to maintain functional residual capacity. In contrast to our study, Chavez et al.[5] extubated their patients directly to nasal prongs. Nasal CPAP has also been shown to prevent extubation failure in preterm infants [6]. By applying the Mapleson D CPAP system to the nasotracheal tube and successively withdrawing the tube from the trachea to the pharynx, we provided CPAP both before and after extubation. By this simple technique, we were able to predict successful extubation as well as to minimize extubation failure.

The main advantage of the Mapleson D CPAP system is that a ventilator is not required. Currently available BiPAP ventilators (BiPAP S/T-D and BiPAP Vision; Respironics. Inc., Murrysville, USA) were primarily designed to treat adults, and their inspiratory triggering systems, expiratory valve mechanics and flow delivery pattern may increase respiratory workload, especially in young children [7–9]. The absence of a ventilator would reduce the additional work of breathing and avoid the asynchrony events due to inspiratory and expiratory triggers. Moreover, the utilization of a reservoir bag and an airway-pressure-limiting valve minimizes the inspiratory workload [10] and may be useful as a defensive mechanism against barotraumas; however, elevated gas consumption owing to higher fresh gas flow rates must be taken into account.

The Mapleson D CPAP system, in our opinion, is an efficient and safe alternative to more complex and expensive noninvasive CPAP and BiPAP apparatus to provide noninvasive CPAP and for weaning from mechanical ventilation in infants. Its technical simplicity makes it extremely suitable in a variety of clinical situations, even outside the PICU.

References

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