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Standard intubation in the ICU 

Standard intubation in the ICU
Standard intubation in the ICU

Sebastian G. Russo

and Michael Quintel

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date: 21 January 2022

Key points

  • Preparation and planning are essential for tracheal intubation in the intensive care unit (ICU).

  • During standard intubation in the ICU administration of neuromuscular blocking agents should be part of the routine.

  • In case of an unexpected difficult airway, the number of intubation attempts should be limited to two and an alternative approach to maintain oxygenation and ventilation, such as extraglottic airway (EGA) devices, needs to be chosen.

  • Whenever ventilator support is required, the use of capnography is mandatory to evaluate ventilation and to confirm clear airways.

  • The intubating laryngeal mask airway (ILMA) is a useful back-up tool for both ventilation and intubation if tracheal tube placement fails.


Airway access or control of the airways to maintain vital oxygenation and ventilation can be assured by different measures—face mask ventilation (FMV), extraglottic airway devices (EGA), endotracheal (ET) tubes, as well as tracheal access via a cricothyrotomy or tracheostomy. This chapter argues with the standard ET placement.

Tracheal intubation in the ICU

Wherever patients require some kind of oxygen administration, the establishment and maintenance of clear airways is the most important task for the caregiver, as without sufficient oxygen supply all other measures remain useless.

For elective conditions direct laryngoscopy is associated with a reassuring high percentage of good views on the laryngeal structures (Cormack & Lehane Score of 1 and 2), as well high success rate for tracheal intubation [1]‌. However, for the intensive care unit (ICU), several authors have indicated that airway management and tracheal tube placement while in the ICU is remarkably more challenging compared with the operating theatre [2,3]. Heuer et al. reported an incidence of difficult intubation of up to 25%, even if performed by anaesthesiologist [4].

Additionally, intensive care patients are critical ill, have reduced respiratory and haemodynamic capacities, and the circumstances and motives for tracheal intubation are awkward (Box 80.1). Thus, the time until desaturation is significantly shorter and the effects of insufficient oxygenation are more damaging. This is also mirrored by the results presented in the fourth National Audit Project in UK [5]‌. The outcome of failures during airway management in the ICU were particular adverse, with a high percentage of death or brain damage. Therefore, similar to the prehospital setting, even standard ET placement in the ICU should always considered to be significantly more difficult compared with elective airway management in the operation theatre (see Table 80.1).

Table 80.1 Reasons why to consider standard oro-tracheal tube placement in the intensive care unit to be difficult



Secretions, blood, oedema

Difficult access to the head

Lung injury with reduced pulmonary reserves

Limited airway management devices

Concomitant haemodynamic instability

Potentially absent of capnography

Limited access to further expertise

Cook et al. have identified several factors contributing to unsuccessful airway management—poor identification of patients at risk, incomplete planning, inadequate provision of skilled staff and equipment, delayed recognition of events, and failed rescue due to lack of or failure of interpretation of capnography. Remarkable, even experienced anaesthetists tend to underestimate the level of complexity, while overestimating their own skills [4]‌. Therefore, it seems to be useful to define a standard procedure for tracheal intubation in the intensive care unit.

Standard intubation


Prior to commencement, it is the health care provider’s responsibility to check for the completeness and functionality of the equipment (see Box 80.2). It is essential that the entire equipment is on scene and not just somewhere in the ICU. Perfect access to the patient is crucial before attempting tracheal intubation. Therefore, whenever possible the strategic and logistical conditions should be optimized.

Whenever possible pre-oxygenation should be performed prior to the induction of anaesthesia. As shown by McGowan and Skinner a tight facemask seal is essential to apply high inspiratory oxygen concentrations [6]‌. In obese patients or in patients with decreased functional residual capacity, pre-oxygenation in the semi-recumbent position, as well as application of a positive end-expiratory pressure (PEEP) increases the interval to desaturation during apnoea significantly. Furthermore, non-invasive ventilation has been shown to be helpful in increasing the efficiency of pre-oxygenation and represents an elegant method of increasing patient safety in the ICU setting [7].

Induction of anaesthesia

In contrast to the most prevalent opinion that length of ICU stay or the fluid balance might influence the occurrence of a difficult intubation, Heuer et al. have shown that some of the main factors contributing to poor intubation conditions are an insufficient depth of anaesthesia and the lack of administration of neuromuscular blocking agents (NMBA) [4]‌. These observations mirror various publications regarding prehospital trauma care indicating that administration of neuromuscular blocking agents significantly increases the likelihood of successful tracheal intubation [8]. Therefore, if the indication for ET placement is given and the decision is made, adequate depth of anaesthesia and full neuromuscular blockade should be ensured.

As depolarizing NMBA are usually not indicated in the ICU setting, because of its fast onset, rocuronium seems to be the most appropriate NMBA. With sugammadex the effect of rocuronium can be reversed. However, the disposal of sugammadex should not lead to a false sense of security. Several authors have questioned whether the administration of sugammadex can save patients’ lives in the case of an unexpected ‘cannot ventilation–cannot intubate’ scenario [9]‌. The time from decision making, to finding and preparation of the adequate dosage until full reversal of the neuromuscular block will probably be longer than the apnoeic tolerance of a critical-ill patient. Additionally, return of spontaneous ventilation will be impaired because of the previous administration of narcotics and, furthermore, will usually not resolve a ‘cannot ventilation–cannot intubation’ scenario [10,11].

Having said that, induction of anaesthesia for the standard intubation—considering no expected difficulties due to patient’s anatomy of the upper airways—in the ICU should, nevertheless, always be performed as a rapid sequence induction. In detail, NMBA should be administered without checking the possibility of ventilation by face mask. There are several reasons for this recommendation:

  • Once narcotics and anaesthetics have been administered recovery from anaesthesia to re-establish sufficient spontaneous ventilation is usually not an option if tracheal tube placement unexpectedly fails in a ‘cannot ventilate–cannot intubation’ situation.

  • NMBA facilitate face mask ventilation and laryngoscopy, as well as placement of an EGA; especially if anaesthesia is light.

  • Finally, the decision for a more defensive pathway needs to be made prior to induction not during.

As shown by Mort, more than two repeated attempts to intubate the patients tracheally are associated with significant-worth outcomes, such as hypoxaemia, regurgitation, aspiration, oesophageal intubation, and cardiac depression [12]. Therefore, it is crucial to limit the number of intubation attempts and consider alternative strategies for oxygenation and ventilation, e.g. EGA or face mask ventilation. While face mask ventilation will most likely serve only as a short time-bridge until other measures have been taken or prepared (such as videolaryngoscopy (VL), intubating laryngeal mask airway (LMA), or flexible fibre optic), an EGA may help also for a several hours to ventilate and oxygenate the patient.

Independently, whether ventilation is maintained by FMV, use of an EGA, or by tracheal tube placement, capnography is mandatory in all circumstances to confirm ventilation and correct placement of any airway device.

Strategies to increase time to desaturation

Apnoic oxygenation is usually known as a minimal oxygenation by placing the facemask tightly on the patients face with simultaneous application of a high oxygen flow. However, an open airway is a conceptual requirement of apnoeic oxygenation.

Ramachandran et al. [13] have performed a study in the operating theatre, including obese patients in the semi-recumbent position increasing significantly the time to desaturation simply by applying 5 L of oxygen via nasal probe during laryngoscopy (Table 80.2). Despite the lack of similar studies in the ICU setting, this concept seems to be very useful due to its simplicity, as well as because nasal probes are widely available. Therefore, it might by sensible to apply oxygen via nasal probes during laryngoscopy in order to prolong the time to desaturation or reduce the degree of desaturation, especially in patients with severe respiratory dysfunction.

Table 80.2 Effect of apnoeic oxygenation with 5 L of oxygen via a nasal probe during direct laryngoscopy

Control group without O2

Study group with O2

Time to SpO2 < 95%, min

3.5 (1.3)

5.3 (1.0)

Lowest SpO2

88 (9)

94 (4)

Time to resaturate, min

1.6 (1.5)

0.7 (0.4)

Data from Ramachandran SK et al., ‘Apneic oxygenation during prolonged laryngoscopy in obese patients: a randomized, controlled trial of nasal oxygen administration’, Journal of Clinical Anesthesia, 2002, 22(3), pp. 164–8. PubMed PMID: 20400000.

Extraglottic airway devices

Since the first description of the classic LMA in 1983 [14], many other types of EGA became available. While EGA have their undisputed value during routine as well as emergency care, the use and distribution of EGA one the ICU seems to be limited.

Difficult laryngoscopy does usually not impair the insertion of an EGA. Therefore, EGA, as extensively shown for the OR and prehospital emergency medicine, are very valuable tools to secure patients’ airways in case of an unexpected failure to intubate in the ICU. As the learning curves to gain adequate competency are steeper for EGA compared with intubation via direct laryngoscopy, they may be especially useful if expertise in advanced airway management is limited.

Available data for the use of EGA in the ICU refer mainly to LMA. Several case reports describe the use of LMAs in the ICU in cases of failed intubations [15]. Furthermore, so called ‘second generation’ devices contain an integrated drainage channel to passively or actively drain fluids from the gastrointestinal tract. Despite the lack of scientific evidence, it can be assumed that these features further reduce the risk of regurgitation. Additionally, as ventilation via a correctly-placed EGA reduces the risk of gastric air insufflation compared with FMV, EGA may serve to provisionally establish clear airways for oxygenation and ventilation.

Blind intubation via EGA is usually not associated with promising success rates. However, intubation via an EGA can be aided fibre optically, possibly with the help of an purpose-designed exchange catheter (Aintree Catheter, Cook Critical Care, Bloomington, IN, USA) [16].

One exception is the intubating laryngeal mask airway (ILMA, Teleflex Medical Europe Ltd, Ireland). It allows ventilation of the patients’ lungs, as well as blind intubation with a very high success rate [17]. Furthermore, for novice users, both ventilation and intubation have proven to be more successful with the ILMA compared with FMV and intubation via direct laryngoscopy [18]. In case of failed blind intubation attempts, tracheal tube placement can easily be performed using a flexible fibre optic. As the airway tube of the ILMA is large, a tracheal tube can be advanced via a fibre optic once the trachea has been identified. Therefore, the ILMA might be a valuable back-up tool when planning tracheal intubation in the ICU.


Currently, standard ET placement usually means the use of direct laryngoscopy. In 1998, the logical combination with a Macintosh blade, the video intubation laryngoscope, was introduced as a new concept for dealing with routine cases, as well as difficult intubations and was the subject of extensive scientific studies. The rapid spread of video laryngoscopy began at the latest with the introduction of the GlideScope® videolaryngoscope (GS-VL, Verthon Medical, Canada) in 2003.

The uncontested preserves of video laryngoscopy are:

  • Training and supervising intubation by laryngoscopy.

  • Laryngoscopic intubation in cases of an unexpectedly difficult airway in adults and children.

  • Assessment and documentation of special constellations and pathological conditions of supraglottic airways and documentation of the tube position in the glottis.

VL systems have shown to improve the view of the laryngeal structures. The view of the glottis is consistently better using a VL system than with direct laryngoscopy. A study by Nouruzi-Sedeh et al., with providers not experienced in airway management, showed that patients were successfully intubated more often and faster with the GS-VL than by direct laryngoscopy [19]. Furthermore, the learning curve for VL seems to be steeper than for direct laryngoscopy, although the data obtained in model-based studies should be regarded with some reservations [20].

Granted, VL is not the Holy Grail for ET placement that will resolve all difficult airway scenarios, and it is self-evident that training and expertise are warranted with the use of VL. However, VL seems to be effective as a back-up device in the case of failed direct laryngoscopy, as well as the first choice tool for health care providers with less skilled in direct laryngoscopy. Furthermore, it can be speculated whether, parallel to the evolution in the OR and the pre-hospital setting, VL will replace direct laryngoscopy in the ICU in the future.

Without going into too much detail about different VL systems and concepts, at this stage it is difficult to predict whether strongly angulated VLs with a mandatory indirect view on the glottis (e.g. GlideScope) or VLs with Macintosh-like blades (e.g. CMac®, K. Storz GmbH, Tuttlingen, Germany), including the option of both indirect and direct laryngoscopy, will be the advantageous in the ICU setting.


Standard tracheal intubation in the ICU is more challenging compared with standard intubation in the OR. Therefore, planning and preparation are crucial. In order to facilitate laryngoscopy and tracheal tube placement, adequate anaesthesia, including full neuromuscular blockade should be part of the routine. EGA devices represent useful options in cases of unexpected failed intubation. However, wherever and whenever airway management is attempted, the use of capnography to confirm ventilation is mandatory. In the future, VL might become the standard procedure for tracheal intubation in the ICU.


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