Awake intubation might be considered in obstetric practice in two situations: management of the mother with a known airway problem, and acute management of the failed intubation after allowing the mother to wake. The need for awake intubation is considerably reduced by the greater proportion of procedures (mainly caesarean sections) performed under regional, rather than general, anaesthesia. Indeed, regional anaesthesia is often considered the technique of choice in both the above situations. Conversely, some authorities would consider a known difficult airway as an indication for awake intubation, since the airway may otherwise be at risk during an inadequate or extensive regional block, and having to deal with a difficult intubation in an uncontrolled manner mid-caesarean is especially hazardous and stressful.
Problems and special considerations
The basic techniques used are the same as for the non-pregnant patient, and fibreoptic intubation is considered the gold standard, although other techniques have also been described. Nerve blocks and transtracheal injection may be difficult because of the increased subcutaneous tissue deposition of pregnancy. Nasal vascular engorgement and a tendency to nosebleeds are common in pregnancy, and so the oral route is often preferred, but nasal intubation is an acceptable route. If the awake procedure follows a failed intubation, there may be considerable airway bleeding and oedema resulting from trauma. In the past, the risk of aspiration of gastric contents has made obstetric anaesthetists wary of obtunding the protective reflexes with local anaesthesia for awake intubation, but this is felt to be safe if excessive sedation is avoided.
There is concern in the UK about the level of training in awake intubation techniques, especially in obstetric patients. Video laryngoscopes are becoming more readily available, and familiarity with their use is increasing, which may lower the threshold for intubation under general anaesthesia in cases suspected to have a difficult airway. Video laryngoscopes have been shown to improve both laryngoscopic view and success at first attempt at intubation of a predicted difficult airway in the non-obstetric population, though studies in obstetric patients are lacking. The time taken to intubate may be longer than with direct laryngoscopy, which may be of concern in the obstetric population. A video laryngoscope may be a more useful tool in the middle of a failing intubation than the fibreoptic ’scope.
Management options
If not already given, H2-receptor antagonists ± antacids should be administered, and secretions reduced, e.g. with intramuscular or intravenous glycopyrronium 100-300 μg up to an hour in advance. If the nasopharyngeal route is chosen, a local anaesthetic with vasoconstrictor must be used.
During the procedure, the same attention to avoidance of aortocaval compression and to fetal monitoring and wellbeing is required as for any procedure in the labour ward. Particular efforts are required to reassure the mother and her partner, since the situations in which awake intubation is required are especially stressful.
Once the trachea has been intubated and the tube’s cuff inflated, general anaesthesia can be induced. It should be remembered that there is a risk of airway obstruction following tracheal extubation, which should be performed only when the mother is awake and in the left lateral position. A bougie or airway exchange device may be placed through the tracheal tube before extubation to facilitate reinsertion of the tube should this be required. Impaired protective reflexes may persist for an hour or more after local anaesthetic techniques have been used in the airway.
Key points
• The indications for awake intubation in obstetrics are controversial.
• The principles of awake intubation are similar to those in non-pregnant women.
Further reading
Baker PA, Weller JM, Greenland KB, Riley RH, Merry AF. Education in airway management. Anaesthesia 2011; 66: 101-11.
Lewis SR, Butler AR, Parker J, Cook TM, Smith AF. Videolaryngoscopy versus direct laryngoscopy in adult patients requiring tracheal intubation. Cochrane Database Syst Rev 2016 (11): CD011136.
Popat MT, Srivastava M, Russell R. Awake fibreoptic intubation skills in obstetric patients:
a survey of anaesthetists in the Oxford region. Int J Obstet Anesth 2000; 9: 78-82.
Scott-Brown S. Russell R. Video laryngoscopes and the obstetric airway. Int J Obstet Anesth 2015; 24: 137-46.