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doi:10.1111/jpc.13078

REVIEW ARTICLE

Respiratory support for children in the emergency department

Andreas Schibler and Donna Franklin
Paediatric Critical Care Research Group, Mater Research University Queensland, Lady Cilento Children’s Hospital, Brisbane, Queensland, Australia

Abstract: Respiratory support in paediatric emergency settings ranges from oxygen delivery with subnasal oxygen to invasive mechanical
ventilation. Recent data suggest that oxygen can cause reperfusion injuries and should be delivered with caution within well-defined clinical tar-
get ranges. Most mild to moderate respiratory distress conditions with an oxygen requirement may benefit from early use of continuous pos-
itive airway pressure. High-flow nasal cannula therapy (HFNC) is an emerging alternative way to support the inspiratory effort combined with
oxygen delivery and positive expiratory pressures without the need of complicated equipment or good compliance from the child. Besides a
positive pressure support effect, HFNC therapy reduces the physiological dead space with improved CO2 clearance. A decrease in heart and
respiratory rate within the first few hours after initiation of HFNC therapy is likely to identify responders of the treatment. The use of non-
invasive ventilation such as continuous positive airway pressure or the use of bi-level positive airway pressure ventilation in emergency depart-
ments has increased, and it has been recognised that continuous positive airway pressure support for older children with asthma is particularly
efficient.
Key words: continuous positive airway pressure; emergency; oxygen toxicity; respiratory distress.

Introduction: The Need of Oxygen Therapy centration and length of exposure.2–4 For these reasons, other
in Acute Respiratory Distress than emergency usage of 100% oxygen, it is recommended that
inspired oxygen concentration (FiO2) should be carefully titrated
Oxygen requirement in a child presenting with acute respiratory against SaO2. In several areas of emergency care and resuscita-
distress is representing the dysfunctional state of pulmonary gas tion, the use of oxygen is now being challenged by new evidence
exchange. The main goal of respiratory support is prevention of from clinical trials and systematic reviews. In neonates, use of
severe hypoxaemia and maintenance of oxygen delivery to pro- 100% oxygen during resuscitation increases mortality, myocar-
tect cerebral function and prevent organ failures.1 It is of utmost dial injury and renal injury,5 and even following an asphyxiating
importance that respiratory support is not discussed in isolation perinatal event, it is thought to increase the risk of cerebral dam-
but related to oxygen delivery, which is defined by the product age.6 The current neonatal resuscitation guidelines advise that
of cardiac output, haemoglobin and haemoglobin saturation the initial gas administered for ventilation should be air (resus.
(DO2 = CO × Hb × SaO2). In a profound hypoxaemic child, rapid org.au/guidelines-section 13 neonatal guidelines). In patients
administration of oxygen is the first line therapy followed by with an acute myocardial infarct, systematic reviews have found
support of the respiratory system. Caution of excessive use of that, compared with room air, there is no evidence that oxygen
oxygen has been recognised, and its toxicity is related to the con- therapy is of benefit,7 as is the case in acute stroke.8 In a long-
term follow-up study of mechanically ventilated adult patients
Key points with acute lung injury, a lower partial pressure of arterial oxy-
gen (but not oxygen saturation) was associated with cognitive
• Oxygen is a drug, and the use of oxygen needs to be ti-
impairment.9 A systematic review, in children with chronic or
trated carefully against measured haemoglobin oxygen satu-
recurrent hypoxia, indicated that high-level or prolonged use
ration. Most causes for an oxygen requirement can be
of oxygen caused adverse effects on development, behaviour
treated with positive pressure support rather than increased
and academic achievement; however, most studies did not strat-
oxygen provision.
ify by SaO2.10
• Maintaining spontaneous breathing in respiratory distress Current WHO guidelines recommend a normal range of
through non-invasive techniques of respiratory support is de- acceptable SaO2 at sea level to be SaO2 ≥ 94%. Thresholds for ad-
sirable to preserve the patients’ own expiratory support/effort. ministering oxygen differ among international guidelines – some
target <92%, whilst others target <94%. The 2012 WHO Recom-
mendations for management of common childhood conditions identi-
Correspondence: Dr Andreas Schibler, Paediatric Intensive Care Unit, Lady
fied a number of key research questions as ‘research gaps’;
Cilento Children’s Hospital, 501 Stanley Street, South Brisbane, Queensland
4101, Australia. Fax: +61 73068 1499; email: a.schibler@uq.edu.au these included ‘Large-scale effectiveness trials of improved oxy-
gen systems on outcomes from pneumonia’ and ‘Clinical studies
Conflict of Interest: None declared. comparing outcomes when oxygen is given at different
Accepted for publication 26 November 2015. thresholds’.

192 Journal of Paediatrics and Child Health 52 (2016) 192–196

© 2016 The Authors
Journal of Paediatrics and Child Health © 2016 Paediatrics and Child Health Division (Royal Australasian College of Physicians)
A Schibler and D Franklin Respiratory support for children

Oxygen delivery is only one side of the gas exchange. Failure of unidirectional flow is directed against the expiratory gas flow
the respiratory system is divided into pump failure (carbon diox- of the patient creating positive expiratory pressures.
ide retention) versus gas exchange failure with a decreased Several studies have shown that HFNC therapy creates a
alveolar–capillary diffusion capacity resulting in oxygenation fail- distending pressure of the lung with a PEEP effect of approxi-
ure. Pump and exchange failure are interlinked. Arterial PaCO2 mately 4–6 cmH2O using flow rates of 1.5–2 L/kg/min in infants
can only be improved by increased alveolar ventilation (greater <12 months of age,12 demonstrating HFNC therapy decreases
gas exchange), either with assisted breathing or by reversing a ce- the work of breathing. Additionally, physiological data suggest
rebral cause for hypoventilation. Oxygen requirement occurs if that flow rates of 1.6–1.8 L/kg/min are matching the majority
(a) the alveolar surface is reduced (atelectasis, consolidation, of inspiratory flows in infants with bronchiolitis.12 Intrathoracic
reduced lung volumes or alveolar surface), (b) ventilation per- (oesophagus) pressure swings are reduced, and the electrical ac-
fusion mismatch is present (increased shunt fraction), (c) venti- tivity of the diaphragm decreased on HFNC therapy.13–15
lation inhomogeneity occurs (increased physiological dead The clinical benefit of high flow in bronchiolitis is subject to
space) and (d) in the presence of an impaired diffusion capacity many current and ongoing trials. Because of its simple applica-
of the alveolar–capillary membrane. Only the latter responds tion, and the fact that little cooperation of the patient is needed,
well to an increased oxygen fraction, whereas the first three HFNC therapy in emergency departments has become popular.
causes respond to increased lung inflation pressures delivered, Particularly, in infants with a moderate oxygen requirement
that is, with continuous positive airway pressure (CPAP) and increased work of breathing, many practitioners have ob-
breathing or mechanical ventilation with positive end expira- served an impressive clinical benefit.16 Observational studies in
tory pressure (PEEP). The respiratory work load is separated emergency and intensive care have shown that infants with
into inspiratory or expiratory work load. During regular breath- bronchiolitis responding to HFNC therapy reduce their heart
ing, the inspiration is active (with the use of diaphragm and and respiratory rate within the first few hours of admission17,18
intercostal muscles) and passive during expiration (elastic recoil and that these criteria discriminate well between responders
of the chest). In the presence of respiratory distress, the expira- (Table 1) and non-responders of HFNC therapy. It has been
tory phase can become active with the use of auxiliary, abdom- recognised that it is important to encourage the early use of
inal and intercostal muscles. To overcome and compensate for non-invasive (non-invasive ventilation (NIV)) respiratory sup-
increased expiratory resistance, patients tend to increase their port or HFNC therapy in less-intensive scenarios, to facilitate
functional residual capacity. This allows an increased airway early respiratory support and decrease the prevalence of respira-
diameter and the use of a higher recoil pressure to work against tory deterioration.19 A recent randomised controlled trial using
airway resistance during the following expiration. In a HFNC therapy in adult patients with acute hypoxic respiratory
paralysed patient, positive pressure ventilation supports only failure showed that HFNC therapy as compared with standard
the inspiratory phase, whereas the expiratory phase is entirely oxygen therapy or NIV resulted in reduced mortality at 90 days.20
dependent on the recoil pressure of the chest and lung. PEEP
may assist to stent airways and maintain functional residual HFNC – how to do it?
capacity. Any spontaneous breathing in a ventilated patient
may assist significantly during the expiratory phase with an Given that the evidence for the use of high flow is rapidly growing
active expiratory effort. In summary, having a spontaneous in the paediatric field, these following suggestions represent a
breathing patient with some form of CPAP and minimal oxygen growing consensus of current practice. Ideally, the flow rate used
exposure is an ideal approach to respiratory support in should match the patients’ maximal inspiratory flow. The individ-
emergency settings. ual inspiratory flow rate is not known in any clinical settings;
hence, as previously suggested, using a flow rate of 2 L/kg/min
High-flow Nasal Cannula Therapy in infants with bronchiolitis will match the expected maximal
inspiratory flow rates in this population. In older children, we
The use of high-flow nasal cannula (HFNC) therapy as an alter- aim to use flow rates of 2 L/kg/min with an upper limit cur-
native form to standard oxygen delivery is rapidly growing rently of 40–60 L/min. This upper limit is based on the reported
despite limited evidence of its efficacy in paediatrics. There are discomfort of patients (noise and nasal distension experienced).
a growing number of studies demonstrating the physiological The oxygen fraction is titrated against SpO2 to maintain values
effect of high flow, which can be summarised as follows: The between 92% and 98%. HFNC therapy is weaned by reducing
inspired gas is heated and humidified and reduces the metabolic FiO2 down to room air preferentially whilst maintaining the
demand associated with gas conditioning. The provision of
warmed and humidified gas to the conducting airways improves
conductance and pulmonary compliance compared with dry, Table 1 Responders to HFNC, CPAP or BiPAP support28
cooler gas. The anatomical nasopharyngeal dead space of the pa- Decrease in respiratory rate
tient is rapidly washed out during the expiratory phase such that Decrease in retractions and accessory muscle use
during the next inspiration, CO2 rebreathing is minimised.11 Reduced FiO2
High flow rates during the inspiratory phase deliver some degree Improved radiological findings (reversed atelectasis)
of respiratory support. Ideally, the delivered flow rate should
match the maximal inspiratory flow rate generated by the pa- BiPAP, bi-level positive airway pressure; CPAP, continuous positive air-
tient in order to avoid the need to entrain gas during inspiration way pressure; HFNC, high-flow nasal cannula therapy.
around the nasal prongs. During the expiratory phase, the

Journal of Paediatrics and Child Health 52 (2016) 192–196 193

© 2016 The Authors
Journal of Paediatrics and Child Health © 2016 Paediatrics and Child Health Division (Royal Australasian College of Physicians)
Respiratory support for children A Schibler and D Franklin

flow rates. Once in room air, the high flow is ceased after 4 h. for NIV.27 Children after upper airway surgery or upper gastroin-
If an oxygen requirement reoccurs after ceasing HFNC ther- testinal tract surgery, and upper gastrointestinal tract bleeding
apy (rebound after PEEP effect is taken off), HFNC therapy is should not be offered NIV. NIV can be provided using a full face
recommenced in room air initially and if needed, FiO2 in- mask or a nasal mask only. The latter is more reserved for long-
creased. A large multicentre randomised controlled trial com- term NIV patients, as factors of mouth opening and leak impact
paring standard oxygen delivery versus HFNC therapy in on the quality of respiratory support. With a full face mask,
moderately sick infants with bronchiolitis is currently being un- CPAP can be delivered with or without positive inspiratory
dertaken in Australia and New Zealand, involving regional and pressure support (PS). The key for success of PS is accurate
tertiary hospitals. triggering, which requires a system with minimal leakage
(tight fit of the mask to face). Commonly, CPAP is commenced
at 5 cmH2O in any child or infant, and the level of CPAP is
Non-invasive Continuous Positive Airway then adapted as clinically needed. It is not uncommon that
Pressure and Bi-level Positive Airway CPAP levels of 10–12 cmH2O are required for improved gas
Pressure exchange. The PS usually initiates at 5 cmH2O above PEEP
Non-invasive ventilation decreases the work of breathing, re- and will then increase if significant work of breathing persists.
verses hypoventilation, increases functional residual capacity, Most infants and children need some form of sedation to
maintains upper airway patency and improves cardiac output tolerate a full face mask, which can be offered with midazo-
with a decrease in oxygen consumption, which is a highly im- lam, chloral hydrate or as aforementioned, dexmedetomidine.
portant factor for a child fatigued by respiratory distress.21 CPAP Responders to NIV are clinically reducing their work of
delivery maintains a continuous set airway pressure during the breathing with a reduction in use of intercostal and auxiliary
inspiratory and expiratory phase, whereas with bi-level positive muscles, resulting in a reduction of heart and respiratory
airway pressure during the inspiratory phase, a greater airway rate. Instead of serial blood gases, the measurement of SpO2
pressure is delivered to support the inspiratory effort. NIV in pae- in relation to the delivered FiO2 is important. If a patient fails
diatric emergency settings is difficult to apply because of the lim- to maintain SpO2 > 92% with a FiO2 < 60%, invasive mechan-
ited compliance and cooperation of infants or children to tolerate ical ventilation should be considered.
a face mask for CPAP delivery. CPAP is usually only tolerated
with some form of sedation, which can compromise respiratory The Transitional Phase During Intubation
drive. Considerably higher levels of nursing skill are required and Mechanical Ventilation
for NIV. Hence, careful consideration regarding the type and
dose of sedation needs to be taken. Since the introduction of Maintaining haemoglobin saturation during airway manage-
dexmedetomidine, the authors’ own clinical practice has ment is critical for patient safety and poses a challenge for the
changed significantly. Dexmedetomidine is an agonist of α2- clinician to secure the airway with tracheal intubation as
adrenergic receptors in certain parts of the brain without any quickly as possible. For a septic patient with severe pneumonia
respiratory depression. The use of dexmedetomidine is cur- who is already hypoxaemic despite oxygen therapy, there is an
rently limited to the paediatric intensive care unit. immediate risk of critical tissue hypoxia during intubation. Pre-
Similar to many other emergency treatments, NIV should oxygenation is the key to avoid or limit induction-related tissue
preferentially be started in emergency departments and then hypoxaemia particularly during a rapid sequence induction.
continued in intensive care.22 Paediatric clinical trials have Prior to rapid sequence induction, an adult patient breathing
shown that the early use of CPAP in asthmatic paediatric patients room air will desaturate within 45–60 s; however, in a child or
is beneficial23,24; however, the studies and reports are predomi- infant, this occurs in less than 20 s. To prevent hypoxaemia,
nantly performed and described from within an intensive care the alveolar space is filled prior to intubation with a high O2 frac-
setting.25 Most of these paediatric trials in asthmatics demon- tion. If saturations remain <94% despite 100% rebreathing
strated an improved oxygenation and reduced need for paediat- bag/mask ventilation, major shunt pathology either within the
ric intensive care admission or intubation. Similarly, the use of lung or on a cardiac level needs to be considered. Pulmonary
CPAP in bronchiolitis has been well documented and described shunt physiology refers to alveoli that are perfused but not ven-
in the literature, but again most likely limited to paediatric inten- tilated because of conditions such as pulmonary oedema, pneu-
sive care settings.26 The use of NIV in adults in emergency de- monia or atelectasis. In the presence of severe respiratory
partment settings has become common practice, and it will be disease, the alveolar space is significantly reduced because of at-
only a matter of time until paediatric emergency services will electasis or pus and secretion, and the diffusion of gas is impaired
use NIV more frequently. Success of NIV can be measured by a because of interstitial thickening with oedema and inflamma-
reduction in heart and respiratory rate within the first few hours tion. The application of CPAP prior to induction may recruit al-
of treatment.27–30 veolar volume. With the introduction of HFNC therapy, this
provides an attractive method for pre-oxygenation with the ap-
NIV – how to do it? plication of CPAP, and without the disadvantage and discomfort
of a face mask. An interesting study by Mundel et al. showed that
Good patient selection is the key to successful NIV. Good patient the application of HFNC therapy reduced the respiratory rate
cooperation and synchrony needs to be established. Children zsignificantly so that other mechanisms of gas exchange such
with reduced conscious level, cardiovascular instability and re- as tracheal gas insufflation were considered.31 In some adult
duced upper airway reflexes or control should not be considered emergency departments, clinicians have started to use HFNC

194 Journal of Paediatrics and Child Health 52 (2016) 192–196

© 2016 The Authors
Journal of Paediatrics and Child Health © 2016 Paediatrics and Child Health Division (Royal Australasian College of Physicians)
A Schibler and D Franklin Respiratory support for children

0.2 INT ETT CMV

SB HB

Relative Lung Volume

a
0.1

0.0

-0.1
0 30 60 90 120 150 180 210 240 270 300 330 360

Time [Seconds]

Fig. 1 Change of relative lung volume during induction of anaesthesia. SB: spontaneous breathing followed by i.v. injection of muscle paralysis, then mask
hand bagging (HB). During insertion of the endotracheal tube (INT), the lung volume is as its lowest level. ETT: manual ventilation followed by continuous me-
chanical ventilation (CMV) applying positive end expiratory pressure.

therapy for pre-oxygenation. The transition from spontaneous to 5 Davis PG, Tan A, O’Donnell CP, Schulze A. Resuscitation of newborn
assisted breathing is also associated with significant shifts in ven- infants with 100% oxygen or air: a systematic review and meta-analysis.
tilation distribution and loss of lung volume.32 Humphrey et al. Lancet 2004; 364: 1329–33.
6 Munkeby BH, Borke WB, Bjornland K et al. Resuscitation with 100% O2
(Fig. 1) showed in infants and children during regular induction
increases cerebral injury in hypoxemic piglets. Pediatr. Res. 2004; 56:
of anaesthesia that there is a significant loss in lung volume and
783–90.
lung mechanics and these changes can be reversed by applying 7 Cabello JB, Burls A, Emparanza JI, Bayliss S, Quinn T. Oxygen therapy
PEEP.33 Infants and children have in comparison with adults a for acute myocardial infarction. Cochrane Db. of Sys. Rev. 2013; 8:
much smaller functional residual capacity of the lung, which CD007160.
normally acts as the oxygen reservoir during induction of anaes- 8 Ronning OM, Guldvog B. Should stroke victims routinely receive
thesia. Hence, any sedation in small infants, even if spontaneous supplemental oxygen? A quasi-randomized controlled trial. Stroke; J.
breathing is being maintained, will rapidly develop into an oxy- Cerebral Circulation 1999; 30: 2033–7.
gen requirement. 9 Mikkelsen ME, Christie JD, Lanken PN et al. The adult respiratory
The use of ketamine, however, may be one of the excep- distress syndrome cognitive outcomes study: long-term
neuropsychological function in survivors of acute lung injury. Am. J.
tional sedatives that may preserve lung volume in healthy
Respir. Crit. Care Med. 2012; 185: 1307–15.
pre-school children undergoing a ketamine anaesthesia for
10 Bass JL, Corwin M, Gozal D et al. The effect of chronic or intermittent
small procedures.34 hypoxia on cognition in childhood: a review of the evidence. Pediatr
2004; 114: 805–16.
Conclusion 11 Dysart K, Miller TL, Wolfson MR, Shaffer TH. Research in high flow
therapy: mechanisms of action. Respir. Med. 2009; 103: 1400–5.
There is a strong physiological rational to shift the paradigm for 12 Milesi C, Baleine J, Matecki S et al. Is treatment with a high flow nasal
first line treatment of mild to moderate hypoxaemia. Initial focus cannula effective in acute viral bronchiolitis? A physiologic study.
of respiratory treatment should be on delivering positive pres- Intensive Care Med. 2013; 39 (6): 1088–94.
sure, followed by, if necessary, increased oxygen fraction. With 13 Hough JL, Pham TM, Schibler A. Physiologic effect of high-flow nasal
the introduction of HFNC therapy, this shift is facilitated as cannula in infants with bronchiolitis. Pediatric Crit. Care Med. 2014; 15:
CPAP, and oxygen delivery is made clinically much easier with e214–9.
one therapy. 14 Pham TM, O’Malley L, Mayfield S, Martin S, Schibler A. The effect of
high flow nasal cannula therapy on the work of breathing in infants with
bronchiolitis. Pediatr. Pulmonol. 2015 Jul; 50: 713–20.
15 Rubin S, Ghuman A, Deakers T, Khemani R, Ross P, Newth CJ. Effort of
breathing in children receiving high-flow nasal cannula. Pediatric Crit.
Care Med. 2014; 15: 1–6.
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Journal of Paediatrics and Child Health © 2016 Paediatrics and Child Health Division (Royal Australasian College of Physicians)
Respiratory support for children A Schibler and D Franklin

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Crocodile’s craving by Ethan Harithupan (13).

196 Journal of Paediatrics and Child Health 52 (2016) 192–196

© 2016 The Authors
Journal of Paediatrics and Child Health © 2016 Paediatrics and Child Health Division (Royal Australasian College of Physicians)