The first published experience, in the early 1970s by Gregory et al., of CPAP in the management of respiratory distress of the newborn launches a new era of ventilatory support in the youngest patients (Gregory et al. 1971). Ventilatory support used by paediatric intensive care units during the last decades reveals that CPAP was rarely used outside the neonatal period and the chronic condition. Specific technical concerns, such as the lack of interface, have hindered for a long time CPAP application in the population of the 3–10 k of body weight. Moreover, the need to maintain a constant pressure during the entire cycle and uncontrolled air leaks has limited the potential benefit of CPAP technique (Gherini et al. 1979). The recent development of devices able to convert the kinetic energy of a jet of gas into a stable airway pressure has allowed the use of CPAP in the youngest (Moa et al. 1988; Klausner et al. 1996). The main aetiology of acute respiratory distress failure in patient of less than 1 year old is lower respiratory tract infections, mainly due to acute viral bronchiolitis. Beasley et al. described for the first time the use of CPAP in the management of 24 patients with severe bronchiolitis with a significant improvement in respiratory rate and gas exchange (Beasley and Jones 1981). During the 1990s, similar benefits were demonstrated by Soong et al. in further ten infants with severe bronchiolitis treated by nasal CPAP (nCPAP) (Soong et al. 1993). Using the Benveniste device (either mononasally or binasally) as a first intention ventilatory support, Kristensen et al. showed that in severely ill infants with viral bronchiolitis a reduced requirement of mechanical ventilation (1.3 %) when compared to previous studies from North America using invasive ventilation as a first support (Kristensen et al. 1998).

In the early 2000s, new interfaces (nasal prongs), which could be used in children over 3 kg of body weight, became commercially available. The nasal prongs facilitated noninvasive pressure support implementation to infants with severe bronchiolitis.

The helmet NIV interface, first developed for the adults, was recently available for children, with the new “baby body” (CaStar; Starmed, Mirandola, Italy), and used for nCPAP implementation in various aetiology of acute respiratory failure (Piastra et al. 2004, 2009).

In the last 5 years, several clinical studies have reported their experience in management of bronchiolitis with nCPAP (Campion et al. 2006; Larrar et al. 2006; Martinon-Torres et al. 2006; Cambonie et al. 2008; Thia et al. 2008). These studies are resumed in the Table 41.1. All studies showed an improvement in breathing pattern, and gas exchange, as well as a low rate of intubation. In addition, nCPAP has been shown to decrease respiratory muscle load in children with upper airway obstruction (Fauroux et al. 2001; Essouri et al. 2005), but no data has been published for young infants with more distal obstructive airway disease. Recently, Cambonie et al. showed that nCPAP can significantly decrease respiratory effort in 12 infants with severe bronchiolitis (Cambonie et al. 2008). We made similar observations in ten infants with acute bronchiolitis and further demonstrated that nCPAP can adequately decrease oesophageal and diaphragmatic pressure time product (PTP_es and PTP_di), reflecting diaphragm oxygen consumption and work of breathing (WOB) (Essouri et al. 2011). Although there is no published consensus, all clinical and physiological data allow us to assert that nCPAP is a good respiratory support in infants of less than 1 year old with viral bronchiolitis.

Implementation of CPAP respiratory support requires to answer to the following questions: (1) When CPAP should be initiated? (2) Which devices should be used? (3) In which setting should CPAP be initiated?

The timing of NPPV initiation in patients with neuromuscular disease has been well established in numerous studies (Robert et al. 1993; No authors listed 1999; Finder et al. 2004), but there is no similar data regarding the criteria for CPAP initiation during acute respiratory failure. However, it is certainly easier to define the non-indication for CPAP than to characterise the clinical parameters leading to the decision to initiate CPAP. Nevertheless, criteria used for nCPAP initiation in published experience of infants bronchiolitis are shown in Table 41.2. Interestingly, authors have quantified the extent of respiratory distress during acute bronchiolitis with the modified Wood’s clinical asthma score (m-WCAS) (Table 41.3) (Hollman et al. 1998; Martinon-Torres et al. 2002; Cambonie et al. 2006). Strength of m-WCAS resides in its use in all children, irrespective of the age, and the easiness of the scoring by any health-care providers. In addition, Cambonie showed that m-WCAS efficiently correlates with respiratory effort intensity measured by the oesophageal pressure (P _es) swings, PTPes/breath and PTPes/mn. Interestingly, a significant correlation between the decrease in P _es swings and use of accessory muscles score is also described (Cambonie et al. 2008). All published data are in agreement with recent experience showing that clinical signs of respiratory distress (increase respiratory rate and high transcutaneous PCO₂) are correlated with an increase in respiratory muscles load and WOB (high oesophageal and diaphragmatic PTP) (Essouri et al. 2011). Based on published experiences, some criteria for the initiation of CPAP during paediatric acute respiratory failure can be suggested: alteration of gas exchange with PCO₂ ≥50 mmHg, clinical respiratory distress with m-WCAS >5, increase in respiratory rate (≥2 SD) and bronchiolitis with recurrent apnea. However, CPAP should be contraindicated in the following conditions: cardiac or respiratory arrest, undrained pneumothorax, nonrespiratory organ failure (hemodynamic instability, severe encephalopathy) and inability to protect the upper airway.

CPAP support requires four components: a ventilator or flow generator, a circuit, a humidifier and an interface. Theoretically, a simple flow generator with an external PEEP can be used to implement CPAP (Beasley and Jones 1981; Soong et al. 1993). Currently, many devices are commercially available, ranging from the simple jet CPAP to polyvalent ventilators used in intensive care unit. The most important parameter is to maintain a stable positive expiratory pressure during the whole respiratory cycle. There is no problem of patient-ventilator synchrony and inspiratory or expiratory trigger as we will see in the NPPV. Cambonie et al. describe that a significant decrease in oesophageal PTP is observed with Infant Flow® (Electro Medical Equipment Ltd, Brighton, United Kingdom) when the level of pressure is achieved (Cambonie et al. 2008). We also describe the same result in decreasing the oesophageal and diaphragmatic PTP with the Babylog 8000^TM (Dräger, Lubeck, Germany) (Essouri et al. 2011). Humidification and warming of the gas delivered are critical even for nasal CPAP, especially when fresh gas is used. Most frequently, duration of CPAP support lasts from a few hours to days until respiratory failure resolves. In such circumstances, exposure to cold gas can lead to local inflammation and delayed healing of the respiratory mucosa (Hayes et al. 1995; Randerath et al. 2002). For young infants, the heated humidifier is the best adapted (Jaber et al. 2002; Lellouche et al. 2002). The circuit between the ventilator, or flow generator, and the interface can be single or double stranded and has to be adapted to the used interface. Prongs and small nasal masks are the most frequently used nCPAP interfaces. The two main systems used in Europe are Infant Flow® (Electro Medical Equipment Ltd, Brighton, United Kingdom) and Fisher & Paykel Healthcare (Auckland, New Zealand). The second one provides prongs available for infants weighing more than 3 k of body weight. A more recent interface is the helmet with the new “baby body”. The modified helmet that seems to be a suitable device for delivering CPAP is well tolerated without major side effects. However, only a feasibility study on 15 children has been published (Codazzi et al. 2006), and no data are available for infants. Several questions remain pendent regarding the helmet system: (1) What is the physiological consequence CO₂ rebreathing? (2) What is the minimal body weight considering that in the smallest, interface overlap may alter thoracic compliance?

As the primary endpoint of the CPAP is to avoid severe respiratory failure leading to invasive ventilation, in patients with an acute respiratory failure, CPAP should be initiated as soon as possible. Thia et al. compared evolution between two groups receiving either early CPAP or delayed CPAP after 12 h of standard therapy. They observed a significant decrease in PCO₂ following early CPAP when compared to delayed CPAP, suggesting that early treatment has prevented the development of additional airway collapse, slowing up and reversing the natural progression of the disease (Thia et al. 2008). Different situations may arise depending on the delay of admission to a PICU. In the last few years, French emergency transport teams were trained to use nCPAP before transfer to an experienced PICU. Although no international recommendation has been published, it can be anticipated that early CPAP, before and outside the intensive care unit, can prevent further respiratory deterioration. The 2001 International Consensus Conferences on noninvasive positive pressure ventilation in adults ARF have stated that “the optimal location for patients receiving NPPV depends upon the capacity for adequate monitoring, staff skill and experience in explaining the procedure, their knowledge of the equipment used, and awareness of potential complications” (Evans 2001).

The physiologic data emanating from studies are scarce, and currently level of CPAP is defined empirically determined on the basis of clinical tolerance and clinical response. Shortly, the CPAP level should be set up to the pressure level achieving a decrease in both respiratory muscle load and work of breathing without increasing air leaks. In published experiences of nCPAP for acute viral bronchiolitis, summarised in Table 41.1, level of CPAP was between 5 and 7 cm H₂O. This pressure level was shown to be effective and safe in infants with mild respiratory distress (Courtney et al. 2003; Martinon-Torres et al. 2006; Cambonie et al. 2008; Martinon-Torres et al. 2008). Based on the recent work of Cambonie et al., we actually know that the level of 6 cm H₂O is adapted for infants with acute obstructive airway distress (Cambonie et al. 2008). With this level of CPAP, there is a homogeneous decrease in the values of inspiratory effort of 53 % for Pes swing, 58 % for PTPes/breath and 59 % for PTPes/mn. These data are in agreement with our own in 10 infants with bronchiolitis managed with a mean level of CPAP of 7 cm H₂O. We observed a significant and homogeneous reduction of oesophageal and diaphragmatic swings from, respectively, 48 and 50 % and from 55 % for oesophageal PTP and 53 % for diaphragmatic PTP (Fig. 41.1). For each infant, we also measured physiological data with high level of CPAP (until 10 cm H₂O) without increase in respiratory effort and in seven infants decrease in the comfort score measured. With low level of CPAP, we observed a decrease in the improvement of oesophageal and diaphragmatic PTP (Essouri et al. 2011). Therefore, based on published clinical experience and physiological data, the recommended level of CPAP for the management of severe acute bronchiolitis is around 7 cm of water.

An additional question is unanswered: Is the level of CPAP support dependant of the age and weight of the patient? The only published data (neonates excluded) are issued from patients with upper airway obstruction. We showed in ten patients that there was no correlation between optimal level of CPAP, defined by the maximum decrease in oesophageal and diaphragmatic PTP and patient age (Essouri et al. 2005).

Incidence of CPAP supports failure, usually defined by the necessity to support respiratory function through invasive ventilation (i.e. orotracheal intubation and mechanical ventilation), has progressively decreased, from 17 to 33 % in the early years of the CPAP therapy for bronchiolitis (Campion et al. 2006; Larrar et al. 2006; Javouhey et al. 2008) to 5 % in the most recent years. Factors associated with the reduction of CPAP failure are now becoming clearer: early CPAP, improvement of interface and health-care provider training in NIV (Essouri et al. 2011).

Despite the recent decrease in failure of CPAP for bronchiolitis, early identification of CPAP failure remains critical as patients requiring invasive ventilatory support have increased morbidity. Some studies have been performed in paediatric patients but are referring to bi-level NPPV (see Sect. 2.2.4). Concerning CPAP support, only retrospective studies are available and concerns acute bronchiolitis (Bernet et al. 2005; Campion et al. 2006; Larrar et al. 2006). A prospective study of NIV (both CPAP and NPPV) in 116 paediatric patients identified three independent risk factors for NIV failure: type 1 acute respiratory failure (defined by Teague (2003)), high PRISM score, and a lower respiratory rate decrease during NIV (Mayordomo-Colunga et al. 2009). However, this study did not look separately to CPAP and NPPV failure. Interestingly, we have reported that high PRISM score during the first 24 h and no and/or a small decrease in PCO₂ during CPAP support were significantly associated with CPAP failure during acute viral bronchiolitis (Larrar et al. 2006). Similar results were found by Campion et al., who showed additionally apnea and higher PCO₂ as risk factors for CPAP failure (Campion et al. 2006) (Table 41.4).

Paediatric patients are prone to a wide range of undesired side effects due to physiologic characteristics related to immaturity of the airway protective reflex, high nasal resistance and tendency to mouth breathe (Teague 2003). Frequent side effects are summarised in the Table 41.5. However, most studies involving young children showed an excellent tolerance to nCPAP. Indeed, skin damage (bridge of the nose, nasal mucosa and upper lip) remains the most frequent complication of CPAP. Fauroux et al. observed that in a population of children with chronic NPPV, skin damage was related to the use of commercial masks (Fauroux et al. 2005). Therefore, reducing the risk of skin damage is among the priority in order to improve tolerance of CPAP. Among the strategy to prevent skin damage, avoiding excessive tight fit is mandatory (Nava et al. 2009). Although frequently mentioned as a complication of CPAP, no pneumothorax was described in the six published clinical studies looking at nCPAP support for acute bronchiolitis (Campion et al. 2006; Larrar et al. 2006; Martinon-Torres et al. 2006; Cambonie et al. 2008; Javouhey et al. 2008; Thia et al. 2008). Agitation and difficulty to adapt to the interface were described but disappeared with the use of oral sedation (30–56 %) (Campion et al. 2006; Thia et al. 2008; Mayordomo-Colunga et al. 2009).

A protocol designed for the medical and nursing staff is required. Clear indications for CPAP initiation and technical hints for how to initiate and maintain CPAP should be established based on the following suggestions (see Fig. 41.2):

The success depends of the quality of the health-care training. Regular sessions are required to optimise the success of CPAP implementation.