44.4.1 What Are the Anesthetic Options If the Patient Is Uncooperative? How Would You Approach the Induction of This Patient?
Children with airway obstruction pose a challenge to the anesthesia practitioner. Physiologically, children have a limited functional residual capacity (FRC), reduced respiratory reserve, increased shunting, and a propensity for airway closure (laryngospasm and bronchospasm). In the setting of a relative increase in oxygen consumption and suboptimal ventilation, the anesthesia practitioner is faced with a patient who will likely develop hypoxemia rapidly. An inhalation induction may be prolonged if there is reduced alveolar ventilation due to airway obstruction.
Anesthetic management in the setting of foreign body aspiration is predicated on providing a safe anesthetic for the patient, while maintaining control of the airway and preventing the undesirable physiologic responses associated with airway manipulation. Inhalational agents may provide an optimal technique to maintain control of the airway.8 Halothane and sevoflurane provide the most rapid and uneventful induction in this scenario. Sevoflurane may be the preferred inhalational agent because it allows for a smooth and rapid induction of general anesthesia. In addition, sevoflurane has antitussive properties and far greater cardiorespiratory stability than halothane.9 The other fluorinated inhalational agents, such as isoflurane, enflurane, and desflurane, are more likely to produce airway irritation on induction and are commonly avoided. However, they may be used following induction to maintain a deep plane of anesthesia.8
Anticholinergics (atropine and glycopyrrolate) block vagally mediated airway responses, such as excessive production of airway secretions, bradycardia, and bronchoconstriction.8 Topical lidocaine works synergistically with the inhalational agent decreasing the physiologic response to laryngoscopy and bronchoscopy. Intravenous opioids, such as remifentanil and fentanyl, are also helpful in suppressing airway reflexes and may be used as an adjunct to the anesthetic, ensuring that the airway is already secured, as there may be associated respiratory depression.8,10 Total intravenous anesthesia with propofol infusion is also a feasible option, as long as spontaneous respiration is maintained. Similarly, small doses of short-acting muscle relaxants provide short-term neuromuscular blockade, inhibit coughing, facilitate oxygenation, and minimize atelectasis.10 The use of muscle relaxants, once again, mandates prior stabilization and control of the airway.10,11
It is generally felt that positive pressure ventilation (PPV) is to be avoided as this may lead to dislodgement and distal displacement of the foreign body.8,10 However, in a retrospective review of 94 children with tracheal and bronchial foreign body, Litman et al found that neither spontaneous nor controlled ventilation was associated with an increased incidence of adverse events.10 Nitrous oxide should also be avoided because it decreases the percentage of delivered oxygen, encourages atelectasis, and expands cavities containing trapped air. Indeed, augmentation of air that is trapped may be of sufficient magnitude to severely compromise pulmonary compliance and generate a pneumothorax.8 Although some might consider awake-intubation to be an option, in this patient, it is likely to be stormy with the potential to dislodge the pushpin and create a more hazardous situation.
When faced with an uncooperative patient or a precarious airway, an intramuscular agent, such as ketamine, may provide a window of opportunity for an inhalation induction, without significant depression of the respiratory drive.12
Although the patient with a foreign body in the airway is considered at high risk for aspiration, the urgency of the airway status takes precedence. If immediate intervention is not indicated, some advocate a waiting period for the patient with a full stomach, while others believe that the stress associated with foreign body aspiration is likely to inhibit gastric emptying and advise against waiting. Likewise, some advocate a rapid-sequence induction to protect the airway, although most believe that a slow inhalation induction with spontaneous ventilation is associated with minimal risk of aspiration and maximizes control. If, however, bag-mask-ventilation is required to maintain or regain control of the airway, then the risk of aspiration increases, mandating early control of the airway.8-11
In this case, our patient provides an interesting twist, as the complexity of the challenge is enhanced by limited neck extension. This case also reflects the importance of communication among the team of caregivers and highlights the need for an alternate plan should the initial approach fail. The inability to predict whether the airway will be easily accessed provides a strong argument for a slow, spontaneous ventilation induction, with topicalization of the airway using lidocaine. Should the airway not be visualized on laryngoscopy, or with a rigid bronchoscope, other modalities may be attempted (McGrath video laryngoscope, lightwand, laryngeal mask airway, etc) provided one has ascertained that blind techniques will not lead to dislodgement or impaction of the foreign body. The specifics of airway management for our patient scenario will be discussed in depth in the next section.