Intravenous induction versus gaseous induction in paediatric patients
Operating department practitioner Arwinder Singh provides an overview of intravenous versus gaseous induction in paediatric patients to assist the anaesthetic team in practice
Paediatric anaesthesia takes into account the unique physiology and technical challenges associated with induction in the child compared with the adult. The aim of this paper is to provide an overview of intravenous versus gaseous induction in paediatric patients to assist the anaesthetic team in practice.
Ideal induction characteristics
Induction agents need to fulfil a certain amount of criteria in order to be considered useful in the clinical setting, in addition to their ability to achieve clinical anaesthesia (Zielinska, Holtby and Wolf, 2011). Ideally, induction should be a smooth, painless process that is rapid and easily accepted by the child, parent and operating room staff (Moore, et al., 2003). Above all, the induction process should be safe, in that it does not result in direct harm to the child nor interfere with metabolic or physiological processes in such a way that harm might ensue (Rappaport, et al., 2011). This includes an agent that does not alter haemodynamic or respiratory stability and one that is safe in the postoperative period (Rappaport, et al., 2011). Postoperative pain, nausea and vomiting and altered mental states are outcomes that should be avoided but can be precipitated by some induction agents (Zielinska, Holtby and Wolf, 2011).
In addition to these concerns, the anaesthetist should select the correct induction agent based on the nature of the procedure and specific patient factors. For instance, difficult airways, stomach contents and the difficulty in establishing venous access may all influence the choice of agent – specifically gaseous or intravenous (Zielinska, Holtby and Wolf, 2011). Therefore, a number of factors need to be considered when selecting the induction agent of choice in paediatric medicine. Furthermore, this choice should be based on the best available evidence for the patient and procedure being performed, where such evidence is available (Cravero and Blike, 2004).
The remainder of this review will focus on these specific ideals of an induction agent in order to determine how the most commonly used gaseous (sevoflurane) and intravenous (propofol) agents meet these criteria, in order to compare their importance for paediatric practice.
Relative advantages of gaseous and intravenous induction
Gaseous agents
The main advantages of gaseous induction include the ease with which the technique can be applied, the speed of induction and the avoidance of intravenous techniques in the child, which may be a source of anxiety and technically challenging (Mellon, Simone and Rappaport, 2007). Gaseous induction agents rely on a high level of solubility between air and blood and fat in order to produce their anaesthetic effect rapidly in the brain (Nolan, 2013). Consequently, agents such as sevoflurane act very rapidly due to their solubility characteristics, and are also relatively short-lived in the body, with unchanged exhalation after a matter of minutes (FRCA, 2004). This suggests that two major advantages to gaseous induction are apparent: firstly, the rapid onset and rapid clearance from tissues indicates that induction will be quick and recovery also quick, and secondly the lack of extensive metabolism of the gaseous agent, as it is exhaled unchanged, would suggest few metabolic side effects (FRCA, 2004).
The primary benefit of gaseous induction agents is considered to be in the administration of anaesthesia in children who are afraid of needles (Nolan, 2013). The process is pain-free and less stressful than needle use in children, particularly those who are agitated or who are moving during the induction process (Lonnqvist and Morton, 2006). Such movement can make intravenous access technically demanding and potentially painful (Beule, et al., 2007). Indeed, pain has been noted in up to 60 per cent of cases of intravenous induction (Mellon, Simone and Rappaport, 2007). Sevoflurane and associated compounds have been shown to reduce anxiety associated with anaesthesia in children and might therefore result in a more refined and effective clinical pathway for the patient and practitioners present (Beule, et al., 2007).
In addition, the use of ventilatory measurements to ascertain the effectiveness of anaesthesia induced by gaseous agents is considered a significant benefit (Breschan and Likar, 2006). The alveolar ventilation characteristics can be monitored during the procedure and constant adjustments made to ensure that the patient remains under anaesthesia throughout the operation (Ahn, et al., 2008). Furthermore, the responses to doses of gaseous induction agents are highly predictable, which is not often the case with propofol and other intravenous agents, where individual variation in response is common and may preclude optimal anaesthesia (Pieters, et al., 2010). Therefore, response to changes in physiology can be anticipated and, in principle, managed more effectively with gaseous agents.
Intravenous agents