**4.3 Management of the unanticipated difficult airway**

Anesthesiologists must be prepared to manage difficult airway situations. Algorithms for the unanticipated difficult airway in the parturient have been developed by national and international organizations.

If intubation fails on the first attempt, a second attempt should be made by a more experienced anesthetist using alternative equipment as appropriate. Ventilation via facemask is recommended if there is a delay in the second attempt. During the second attempt at intubation, cricoid pressure should not be applied (see **Figure 2**) [49]. In addition, a second attempt at intubation should not be continued if there is a Cormack-Lehane grade 3b or 4 view at laryngoscopy to prevent airway trauma and loss of airway control [49, 93–95]. In case of two unsuccessful intubations, the anesthesiologist should declare a failed intubation and proceed to the failed intubation algorithm according to the OAA/DAS guideline (see **Figure 2**). However, in the presence of experienced anesthetist, this guideline also allows for a maximum of three attempts at intubation before declaring a failed intubation [49, 96].

## **Figure 2.**

*Safe obstetric general anesthesia. Reproduced from Mushambi et al. [49], with permission from obstetric Anesthetists' association/difficult airway society.*

#### **Figure 3.**

*Management of failed tracheal intubation in obstetrics. Reproduced from Mushambi et al. [49], with permission from obstetric Anesthetists' association/difficult airway society.*

If a failed intubation has been declared, airway management consists of three steps including (1) calling for help, (2) maintaining adequate oxygenation, (3) determining whether proceed or wake the patient (see **Figure 3**) [49]. A more experienced anesthesiologist should be called immediately to help in airway management [2, 3, 28, 29, 49]. To maintain adequate oxygenation, ventilation can be performed through a facemask or supraglottic airway device. When performing facemask ventilation, it is recommended to use the two-person (four-handed) technique and to reduce or release the cricoid pressure [28, 29, 49]. If facemask ventilation is found to be difficult or inadequate, a supraglottic airway device should be inserted immediately before the effects of the induction agent and NMD wear off [49]. The second-generation supraglottic airway device is recommended as it has an additional esophageal drainage port and oropharyngeal cuff to reduce the risk of pulmonary aspiration [28, 29, 49]. During the insertion of supraglottic airway device, cricoid pressure should be temporarily removed. Only two attempts at supraglottic device insertion should be performed in order to prevent bleeding or further airway trauma. Once the adequate oxygenation has been established, the anesthetist and team should determine whether to proceed with surgery or wake the patient. The final decision should be based on consideration of several factors that have been evaluated preoperatively (see **Figure 1**) [49] However, the presence of airway hazards and the degree of difficulty in airway management remain major factors in decision-making because maternal safety is a top priority for the anesthesiologist. If there is no evidence of a difficult airway or a life-threatening condition for the mother, the safest strategy is to awaken the mother. If the mother is in immediate jeopardy and no other anesthetic technique is feasible, anesthetist should consider proceeding with surgery. On the other hand, if the mother is stable with a life-threatening condition

of the fetus, it is advisable to consider waking the mother. Despite the controversial decision, the risks of an unsecured airway and the increased risk of aspiration are considered to outweigh the benefits of proceeding with surgery [2, 49]. This is a difficult decision, and evidence does support both sides. Several studies have shown that continuing surgery with a well-functioning supraglottic airway device following failed tracheal intubation is considered as safe and is also recommended [29, 97].

In the setting of a failed intubation, if the decision is made to wake the patient, the anesthesiologist must maintain adequate oxygenation and prevent pulmonary aspiration by applying cricoid pressure and changing the patient position to head-up or left-lateral position. In addition, the anesthesiologist should also assess for the possibility of persistent paralysis and laryngeal spasm. If there is persistent paralysis, sugammadex can be used to reverse the effects of rocuronium. To anticipate the occurrence of laryngeal spasm and "can't intubate, can't oxygenate" (CICO) situations, the anesthesiologist must also prepare the appropriate equipment, drugs, and personnel. Following waking, the obstetrician should review the urgency of delivery, and anesthetist should consider the safest alternative anesthetic option for the patient. Options for anesthetic technique include (1) regional anesthesia or (2) general anesthesia preceded by awake intubation or tracheostomy [2, 49]. If regional anesthesia is selected, anesthetist should prepare for a backup plan in case high or failed block happened. If general anesthesia is selected, awake intubation using video laryngoscope or flexible bronchoscope with topical anesthesia is recommended [49, 98, 99]. However, in the event of extreme difficulty or failure of tracheal intubation via upper airway, tracheostomy should be performed immediately [49].

If the decision to proceed with surgery has been made in the setting of failed intubation, anesthesiologist should consider the following issues: (1) maintenance


#### **Figure 4.**

*Management after failed tracheal intubation in obstetrics. Reproduced from Mushambi et al. [49], with permission from obstetric Anesthetists' association/difficult airway society.*
