Which ONE of the following techniques provides the best visualisation of the vocal cords during rapid sequence intubation (RSI)?
Answer: B: Sellick’s manoeuvre, in which an assistant applies cricoid pressure during intubation to prevent aspiration, may worsen the laryngoscopic view. All of the remaining manoeuvres are associated with improved visualisation of the vocal cords but it appears that bimanual laryngoscopy, a technique where the intubator manipulates the larynx with their right hand until visualisation, and then an assistant maintains the position, provides better visualisation. The BURP manoeuvre is where the assistant applies backwards-upwards-rightwards pressure on the thyroid cartilage.
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Cricoid pressure using Sellick’s manoeuvre is commonly used during RSI.
Which ONE of the following is TRUE?
Answer: D: For many years cricoid pressure has been advocated as the standard of care during RSI for preventing aspiration. The evidence supporting the widespread use of cricoid pressure to prevent aspiration is, however, unconvincing by current standards of evidence-based medicine. Cricoid pressure generally impairs BVM ventilation, worsens laryngoscopic view and impairs insertion of the tube over an endotracheal introducer. Although evidence does not support its effectiveness in RSI, many practitioners still use it. The routine use of cricoid pressure to prevent aspiration is no longer recommended. If cricoid pressure is used, the pressure should be adjusted, relaxed or released if it impedes ventilation or placement of an advanced airway.
Regarding laryngospasm as a cause of upper airway obstruction, which ONE of the following is TRUE?
Answer: C: Upper airway obstruction due to laryngospasm can occur during the induction of anaesthesia or post-extubation. A variety of triggers are recognised including movement of the cervical spine, vocal cord irritation from blood, vomitus or oral secretions, pain or sudden stimulation while the patient is still in a light plane of anaesthesia. In some cases the triggers are not identified. A recent respiratory tract infection or exposure to passive cigarette smoke may predispose patients to laryngospasm on emergence.
Laryngospasm can persist long after the causative stimulus has ceased.
Laryngospasm has the potential to cause increased morbidity and mortality due to severe hypoxaemia, pulmonary aspiration and postobstructive pulmonary oedema. The proposed mechanism of pulmonary oedema is the generation of high negative pressures during respiratory effort associated with glottis closure and laryngospasm.
Although laryngospasm can occur in both adults and children, it is more common in children, being highest in infants 1–3 months of age. Bradycardia may also complicate laryngospasm and hypoxaemia, especially in young children. Bradycardia accompanied one-fifth of cases under 1 year of age in the Australian Incident Monitoring Study.
The laryngeal mask airway (LMA) is a successful rescue device in emergency airway management.
Which ONE of the following statements is TRUE regarding the LMA?
Answer: C: The LMA is a useful alternative to endotracheal intubation when an advanced airway is required but it is not a definitive airway and doesn’t protect the patient from aspiration. Positioning of the patient into the ‘sniffing’ position is not essential but it is preferable. The LMA should not be held while the cuff is being inflated to allow the LMA to seat properly. The LMA tube on average will move out of the mouth approximately 0.7% during inflation. The LMA can potentially be placed too deeply if the tube is held in place during inflation and not allowed to rise slightly.
Regarding the management of the airway and ventilation in a morbidly obese patient, which ONE of the following statements is TRUE?
Answer: A: The optimum approach to intubation of the morbidly obese is unclear. Positioning the patient in the ‘ramp’ position appears to improve the laryngoscopic view compared with the standard ‘sniffing’ position. The ramp position can be achieved by elevating the head and shoulders with blankets/pillows/wedge such that the external auditory meatus and the sternal notch are horizontally aligned. Clearly this approach is not suitable in trauma patients with suspected cervical spine injuries.
Obesity alters the pharmacokinetics and pharmacodynamics of many medications. In contrast ANSWERS 242 CHAPTER 12 Emergency Anaesthes ia and Pain Mana gement to induction agents, there is consistent evidence from the literature to guide the dosing of neuromuscular blocking agents. Suxamethonium should be dosed according to total body weight as dosing based on ideal body weight provides inadequate paralysis and poorer laryngoscopic views. Nondepolarising neuromuscular blocking agents such as vecuronium and rocuronium should be dosed according to ideal body weight because recovery may be prolonged when dosed according to total body weight. Ideal body weight can be estimated by various formulae. The Devine formula is the most commonly used formula and can be calculated as follows:
Ventilation can pose another challenge. Tidal volumes are calculated based upon the patient’s ideal body weight (obesity does not change underlying lung volumes) and then adjusted according to the clinical response, using airway pressures, oxygen saturation and blood gas results.
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