*2.1.3 Anesthesia induction and pharmacological considerations*

Hypnosis, analgesia and skeletal muscle relaxation is a triad to commence general anesthesia required for airway management and instrumentation. A variety of pharmacological agents are described to achieve this task with specific considerations in dosing titration, delayed onset and extended effect duration.

Airway management of critically ill patients is mostly carried out in ICU while the risk to be done in non-ICU suites still considerable. Non-ICU suites include prehospital area, emergency department, radiology department and inpatient ward which carry the risk of difficultly and hence increase in adverse consequences of airway management, that will be discussed separately in corresponding chapters.

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*Airway Management in Critical Settings DOI: http://dx.doi.org/10.5772/intechopen.93923*

ment by ETT.

*2.1.3.1 Induction agents*

ful tracheal intubation by waveform capnography.

good seal and preoxygenate for at least 3 minutes [19].

There are many factors recommended to reach the optimal airway management in critically ill patients including; intravenous induction agents, use of fast onset neuromuscular blocking agent (NMBA), precautions against pulmonary aspiration, laryngoscopic techniques aimed at first-pass success, and confirmation of success-

Rapid sequence induction and intubation (RSII) is a technique commonly used to protect the airway against gastric contents aspiration and modified to be implemented in some clinical circumstances. A classic RSII consists of oxygen administration, application of cricoid pressure, and the avoidance of mask ventilation before insertion of an endotracheal tube (ETT) for airway securement [26].

A modified RSII in comparison to a classic RSII is to attempt for lung ventilation using positive-pressure ventilation via a facemask [27] before airway secure-

Delayed sequence intubation (DSI) seems to be safe, effective and could offer an alternative of rapid sequence induction in patients requiring emergency airway management who cannot tolerate preoxygenation or peri-intubation procedures [28]. The ideal DSI induction agent is Ketamine as it preserves airway reflexes and respiratory drive permitting preoxygenation and procedural sedation. DSI technique steps are; ensure the patient has a patent airway, place standard nasal cannula at 5 liters/min in awake patient and increases to 15 liters/min in unconscious one prior to placement of the preoxygenation device. Preoxygenation device choices based on the patient's SpO2: if SpO2 > 95% use bag-valve-mask (BVM) with PEEP valve and a good seal at 15 L/min O2, or non-rebreather (NRB) mask and a good seal at 15 L/min O2 (or more) while SpO2 < 95%: use BVM with PEEP valve and a

Choice of induction drug is according to hemodynamic status of the patient; Ketamine is increasingly favored in most circumstances [29]. Administration of a rapidly acting opioids enables lower doses of hypnotics to be used, maintaining

Etomidate as an induction agent is not a first line for intubation in the critically ill patients because the other induction agents have been successfully used without risk of adrenal suppression. Its relative value of short-term hemodynamic stability that is accompanied by a potential adverse effect of adrenal suppression making its use as an anesthetic induction agent in critically ill patients is controversial, although it provides excellent intubating conditions [30]. Another meta-analysis also investigating non-intubation-related adverse effects of Etomidate in critically ill patients stated that its use is not worsening of mortality, organ dysfunction or resource utilization, even if it's adverse effects on adrenal gland function [31]. It's found that hypotension was more prevalent in patients receiving Etomidate compared with Ketamine in the

Dexmedetomidine, Remifentanil and Droperidol have been suggested as induction agents for DSI, but these agents do not have the same pattern of Ketamine as rapid onset, preservation of airway reflexes, intact respiratory drive and safety profile. Fentanyl have a significant sedative effect in addition to analgesia, that may

cardiovascular stability and minimizing changes of intracranial pressure.

first 24 hours after intubation and subsequent mechanical ventilation [32]. Moreover, Propofol has temporary hypotension episodes as compared to Etomidate, but there is no difference in patients requiring vasopressors after 24 hours [33]. Propofol and Ketamine mixture may have an improved hemodynamic profile compared with Etomidate. Few studies evaluated Etomidate versus

be helpful when titrated to the desirable effect and to avoid over sedation.

Ketamine, finding no difference between them [34].

#### *Airway Management in Critical Settings DOI: http://dx.doi.org/10.5772/intechopen.93923*

*Special Considerations in Human Airway Management*

*2.1.3 Anesthesia induction and pharmacological considerations*

*DAS/ICS/FICM/RCoA guidelines for ETI in critically ill patients.*

Hypnosis, analgesia and skeletal muscle relaxation is a triad to commence general anesthesia required for airway management and instrumentation. A variety of pharmacological agents are described to achieve this task with specific consider-

Airway management of critically ill patients is mostly carried out in ICU while the risk to be done in non-ICU suites still considerable. Non-ICU suites include prehospital area, emergency department, radiology department and inpatient ward which carry the risk of difficultly and hence increase in adverse consequences of airway management, that will be discussed separately in corresponding chapters.

ations in dosing titration, delayed onset and extended effect duration.

**90**

**Figure 7.**

There are many factors recommended to reach the optimal airway management in critically ill patients including; intravenous induction agents, use of fast onset neuromuscular blocking agent (NMBA), precautions against pulmonary aspiration, laryngoscopic techniques aimed at first-pass success, and confirmation of successful tracheal intubation by waveform capnography.

Rapid sequence induction and intubation (RSII) is a technique commonly used to protect the airway against gastric contents aspiration and modified to be implemented in some clinical circumstances. A classic RSII consists of oxygen administration, application of cricoid pressure, and the avoidance of mask ventilation before insertion of an endotracheal tube (ETT) for airway securement [26].

A modified RSII in comparison to a classic RSII is to attempt for lung ventilation using positive-pressure ventilation via a facemask [27] before airway securement by ETT.

Delayed sequence intubation (DSI) seems to be safe, effective and could offer an alternative of rapid sequence induction in patients requiring emergency airway management who cannot tolerate preoxygenation or peri-intubation procedures [28]. The ideal DSI induction agent is Ketamine as it preserves airway reflexes and respiratory drive permitting preoxygenation and procedural sedation. DSI technique steps are; ensure the patient has a patent airway, place standard nasal cannula at 5 liters/min in awake patient and increases to 15 liters/min in unconscious one prior to placement of the preoxygenation device. Preoxygenation device choices based on the patient's SpO2: if SpO2 > 95% use bag-valve-mask (BVM) with PEEP valve and a good seal at 15 L/min O2, or non-rebreather (NRB) mask and a good seal at 15 L/min O2 (or more) while SpO2 < 95%: use BVM with PEEP valve and a good seal and preoxygenate for at least 3 minutes [19].

#### *2.1.3.1 Induction agents*

Choice of induction drug is according to hemodynamic status of the patient; Ketamine is increasingly favored in most circumstances [29]. Administration of a rapidly acting opioids enables lower doses of hypnotics to be used, maintaining cardiovascular stability and minimizing changes of intracranial pressure.

Etomidate as an induction agent is not a first line for intubation in the critically ill patients because the other induction agents have been successfully used without risk of adrenal suppression. Its relative value of short-term hemodynamic stability that is accompanied by a potential adverse effect of adrenal suppression making its use as an anesthetic induction agent in critically ill patients is controversial, although it provides excellent intubating conditions [30]. Another meta-analysis also investigating non-intubation-related adverse effects of Etomidate in critically ill patients stated that its use is not worsening of mortality, organ dysfunction or resource utilization, even if it's adverse effects on adrenal gland function [31]. It's found that hypotension was more prevalent in patients receiving Etomidate compared with Ketamine in the first 24 hours after intubation and subsequent mechanical ventilation [32].

Moreover, Propofol has temporary hypotension episodes as compared to Etomidate, but there is no difference in patients requiring vasopressors after 24 hours [33]. Propofol and Ketamine mixture may have an improved hemodynamic profile compared with Etomidate. Few studies evaluated Etomidate versus Ketamine, finding no difference between them [34].

Dexmedetomidine, Remifentanil and Droperidol have been suggested as induction agents for DSI, but these agents do not have the same pattern of Ketamine as rapid onset, preservation of airway reflexes, intact respiratory drive and safety profile. Fentanyl have a significant sedative effect in addition to analgesia, that may be helpful when titrated to the desirable effect and to avoid over sedation.

NMBA improves intubating conditions, facemask ventilation, nasogastric tube insertion hence, reduction in the number of intubations attempts and optimizing chest wall compliance [35]. Succinylcholine has many side-effects including lifethreatening hyperkalemia and its short duration of action can spared for difficult intubation scenarios. Rocuronium could be the choice in the critically ill patients, providing similar intubating conditions to Succinylcholine and can be antagonized using Sugammadex [36].

Graded sedation intubation without use of NMBA has also been proposed and clinically considered for technique of choice of airway management in critically ill patients [37].

#### **2.2 Intervention stage**

This is the subsequent stage, that follows patient's optimization achieved through concomitant preoxygenation, positioning and preparation of staff, equipment and medications. It is a highly stressful time and must be carried out in a strictly controlled and strategic manner.

Current guidelines state four main routes or plans as standard practice and should be done in sequence. From practical point, we believe that algorism might be modified or interchanged according to the given circumstances, such as in ED and prehospital critical settings, health care professionals could go for plan B/C straight away bypassing plan A because of limited facilities and unsuitable environment that mandate minimal airway manipulation with accomplishment of securing airway patency, proper oxygenation and/or ventilation.

#### *2.2.1 Plan A*

Plan A stresses on maintenance of oxygenation either via continuous nasal cannula or interrupted facemask application between laryngoscopic attempts and allowing enough time for desirable effect of pharmacological agents, laryngoscopy attempts using direct (DL) or video-laryngoscope (VL).

With a maximum of three trials, confirmed endotracheal intubation (ENI) through capnography with waveform trace and direct visualization of ETT pass beyond the vocal cords, the call for help of the appropriate help once failed first attempt is a must. Absence of wave trace capnography is a confirmation of failed ETI after exclusion of other causes such as ETT obstruction, pulmonary edema and cardiac arrest. Chest auscultation and its rise during inspiration are rarely used as indicator for successful ETI in critically ill patients [38].

First attempt of ETI, must be done by the most trained, proficient available and must have all team support and consideration of manoeuvers or manipulations with the aim of improving laryngoscopy is recommended after failed first attempt [19]. Operator replacement and equipment change; use of a different blade, addition of others; bougie and external laryngeal manipulation might be reasonable and helpful.

Despite of fulfilling all the available recourses to achieve an optimal laryngoscopic view, with failure of the ETI attempts, either three done or not, the team leader must swiftly proceed to the next airway management plan. DL is the standard use in ETI during daily clinical practice hence its use experience is granted. On the other hand, VL should be in preparation for difficult situation; MACOCHA score > 3 [11] and ensure its availability for critically ill patient management. DL versus VL is the choice of the professionals involved in the airway management scenario and could be the device selected for first attempt according to the institutional policy and training preferences [39].

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to equipment failure.

*Airway Management in Critical Settings DOI: http://dx.doi.org/10.5772/intechopen.93923*

among the airway management team [19].

Critically ill patients' lifesaving by maintaining oxygenation during airway management is the priority and failed ETI [8] in the preceding plan A could resulted in sever hypoxemia [6, 40] that has several serious consequences. It's the responsibility of the team leader to ensure maintenance of adequate oxygenation throughout the stages of airway management. ETT considered as a standard and definitive airway securing device while alternatives used to provide oxygenation in scenarios of failed ETI such as supraglottic airway (SGA) devices and facemask ventilation device. SGA is considered as a plan B rescue device which consist of variety of devices used for the same purpose; securing upper airway patency that does not require long experience. Facemask ventilation used as a plan C with the purpose of providing O2 till an alternative being fixed. DAS/ICS/FICM/RCoA guidelines use SGA (plan B) and facemask ventilation (plan C) alternatively to ensure oxygenation after

plan A failure confirmation with maximum three turn attempts [19].

quent positive pressure ventilation-related pneumomediastinum [44].

*2.2.3 Plan D; life-saving front of neck airway (FONA)*

Second-generation laryngeal mask airways (LMA) not only possess a design of providing oxygenation, reduce the aspiration risk and conduit for fiberoptic intubation (FOI) [40], but also, promising successful performance in critical areas have been reported [41] so, it's the model of SGA devices to be considered in standard practice and should be available in the difficult airway management trolley. Provision of oxygenation, airway securing, avoidance of aspiration with minimal airway trauma, constantly remain the goals throughout the intervention and subsequent plan to awake patient, wait for airway expert, Fiberoptic Intubation (FOI) through LMA attempt for once or proceed to FONA remains the area of discussion

Basically, it's not recommended to proceed for blind ETI via LMA, [42] on the other hand, FOB accessibility in ICU should be granted [14, 43]. There are alternatives to perform LMA/FOI-guided either using small ETT 6.0 mm inner diameter mounted over the FOB to be advanced through LMA or using Aintree intubation catheter (Cook Medical, Bloomington, IN, USA), that permits ETT > 7.0 mm inner diameter without interruption of oxygenation. Blind ETI with use of either gum elastic bougie or tube exchange catheter (Frova catheter; Cook Medical, Bloomington, IN, USA) is not advisable in critically ill patients as it's associated with tracheal injury, pharyngeal perforation, bronchial bleeding and accused for subse-

Life-threatening hypoxemia development in critically ill patients is frequent [45] and might be encountered at any stage of airway intervention, hence its prevention though ETI (plan A), SGA and facemask (plan B/C) use is emphasized. Not only, plan of failure with serious hypoxemia elaboration could drive towards FONA (**Figure 8**) but also, inadequate minimal oxygenation, aspiration, difficult ventilation and failure of LMA/FOI are potential indications [46]. Forever, efforts to eliminate cannot intubate cannot oxygenate (CICO) scenario must be maintained and its causes must be corrected while preparation of FONA is being proposed. The possible reasons for CICO might be related to patient's (airway; impacted foreign body or laryngeal narrowing either from inside as laryngeal edema or from outside as high cricoid pressure), cardiovascular collapse or related

Late FONA during airway management scenario is common and is responsible for its associated morbidity and mortality [43, 47]. FONA setup prior to and at declaration of CICO occurred in three steps; immediate availability of FONA set,

*2.2.2 Plan B/C: (backup plan)*
