Changing landscape of tracheal intubation in the very young

Tracheal intubation in children is performed daily in the operating room but also occurs commonly in other settings such as the emergency department, intensive care and hospital wards. Although tracheal intubation is considered routine practice for anaesthesiologists, it is potentially associated with the risk of severe desaturation1 resulting in hypoxic encephalopathy, cardiac arrest2,3 and death.4 Optimising modifiable risk factors, such as patient condition, the time and place of intubation and available equipment, as well as human resources, are critical in improving outcomes for tracheal intubations. Although considerable efforts have been made in the perioperative arena in recognising the importance of patient preparation, the advances in technology and identification of new techniques commonly employed outside the operating room have also changed the landscape of tracheal intubation. Video-laryngoscopy results in a significantly improved first-pass intubation success rate, particularly in very young patients and when the operator is less experienced.5,6 However, it is well recognised that despite a good visualisation of the larynx and arytenoids, intubation may require more than one attempt.7 The inability to successfully intubate despite an ‘easy’ Cormack–Lehane score of 1 or 2 results in multiple attempts and a subsequent classification of difficult intubation (two failed attempts of intubation).7 It is unlikely that further modifications to an already good view using either different models of video-laryngoscopy or other modern tools will change the incidence of difficult intubation. Therefore, the expertise of the operator to complete atraumatic tracheal intubation, the use of neuromuscular blocking agents as well as the time is taken to successfully perform this procedure need to be considered in addition to the laryngeal view during laryngoscopy. Several professional and scientific societies proposed and advocated the need for a curriculum and test of proficiency for tracheal intubation for healthcare practitioners across various specialties. The experience of the operator performing tracheal intubation affects the success rate and the quality of intubation. The exposure and expertise of the operator could be increased by limiting tracheal intubations to fewer but skilled staff. This may, however, expose patients to an enormous risk if staff become unavailable and the backup fails to materialise. The impact of human factors such as fatigue, hierarchy, (lack of) leadership and stress in determining the success or failure of airway management should not be underestimated. Apart from being well prepared, the intubation procedure can be facilitated by using neuromuscular blocking agents. Neuromuscular blocking agents have been demonstrated to facilitate tracheal intubation by limiting functional airway obstructions, especially when the operator is inexperienced or still requires teaching and supervision.8 Routine use of neuromuscular blocking agents in children with anticipated ‘normal’ airways should be a standard to reduce trauma and subsequent morbidity.8 The time taken to complete successful tracheal intubation is commonly perceived as the critical step in patients with limited physiological reserves. Apnoeic oxygenation using humidified, high-flow nasal oxygenation systems during tracheal intubation has been demonstrated to reduce the incidence of hypoxemia as well as increase the apnoea tolerance or the time available to perform tracheal intubation. In addition, it improves the first-attempt success rate and decreases respiratory complications and/or haemodynamic instability. An increase in the time available for intubation will benefit not only the less experienced or novice operator for the routine case but also in the most critical and fragile patients. It negates the need for interrupting the manoeuvre to re-ventilate and oxygenate the patient despite a good laryngeal view and will hence reduce the stress on the operator as well as on the supervisor. Peri-intubation supplementary oxygen administration is simple, has very few complications and is rarely contraindicated in children.9 In addition, there is no evidence that a short period of hyperoxia in children, even during neonatal age, overcomes the well-known consequences of an equal duration of hypoxia.10 The risks and potential harm of high-dose oxygen administration in term and preterm neonates have been pointed out in several publications. High systemic oxygen supply could induce oxidative stress with inflammation, vasoconstriction, impaired microcirculation and organ dysfunction.11 Consequently, PaO2 within a range of normality should be maintained at all times. However, the ‘range of normality’ includes upper and lower limits. If the short and long-term consequences of a few minutes of hyperoxia still need to be demonstrated, the same cannot be said for a similar period of hypoxemia which has a high probability of causing neurological sequelae. If survival of the patient is dependent on the balance between systemic and pulmonary circulation (e.g. hypoplastic left heart syndrome), then a high inspired oxygen concentration is detrimental to the patient and must be avoided. The provision of supplementary oxygen as part of an ‘airway management bundle’ may decrease the incidence of complications during airway instrumentation. Such an ‘airway management bundle’ may consist of pre-oxygenation of the patient via face mask ventilation until the expired oxygen concentration is approximately 90% and continuation of supplementary oxygen throughout the procedure. This allows the operator to perform the tracheal intubation via the chosen route using either direct or video laryngoscopy without the threat of rapid hypoxemia. The provision of supplementary peri-intubation oxygen should be included in a simple pre-intubation checklist prepared for daily clinical practice.12 Several questions remain and require careful consideration. First, supplementary oxygen can be administered either low or high flow (0.2 versus 2 l kg−1) via either nasal cannulae or a nasopharyngeal tube. Oxygen can be humidified and mixed with air using a blender. Do all techniques prolong safe apnoea time equally and if not, which one would be the best approach?13 Second, high-flow oxygen has several other intrinsic limitations: humidified and warmed gas in the clinical setting of the operating room is not always available. In addition, it may not generate sufficient positive pressure to overcome functional or mechanical airway obstructions and to protect the functional residual capacity in apnoeic patients.14 Therefore, is humidification and heating of the gas required in all patients, or does it only serve to protect mucosal membranes integrity?15 Thirdly, the administration of lower concentrations of oxygen (e.g. inspired oxygen concentration of 30% or less), even when applied with a higher flow (2 l kg−1), does not prolong the safe apnoea time in a clinically relevant way, whereas a high inspired oxygen concentration does, even when administered only at a low-flow rate via nasal cannulae.16 This is critical when considering low-resource settings where the supply of high-end products might not always be available. Finally, a prolonged cessation of ventilation during intubation may also affect carbon dioxide clearance. Although a ventilatory effect using high-flow nasal oxygen was originally suggested,17 this was not observed in adult or paediatric clinical studies.18 With carbon dioxide expected to rise approximately 3 to 5 mmHg min−1 the changes are unlikely to be clinically relevant, assuming the apnoeic time is kept to a minimum. It remains to be determined which are the optimal flows and oxygen concentration of oxygen to maintain oxygenation. Regardless of the open questions, additional oxygen during tracheal intubation gains precious additional time and allows the operator, even those perceived to be less skilled, to complete tracheal intubation at the first attempt in a controlled and less stressful environment. Supplementary oxygen administration represents a simple method that can be safely practiced every day and its use should be implemented future in guidelines and algorithms for paediatric airway management, similar to adults.19 Therefore, supplementary oxygen by nasal cannulae is an easy way to increase safety by gaining more time for tracheal intubation. The benefits outweigh any potential challenges and supplementary oxygen should be used for every young child requiring tracheal intubation.

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