Intubation

 

Indications

 

Indications for intubation in patients with trauma include:

• Loss of airway patency
  • Airway burns
  • Facial/neck trauma
  • Foreign material in airway (teeth, vomit, blood)

• Loss of airway protection
  • Decreased GCS
  • Respiratory/cardiac arrest

• Poor oxygenation or ventilation
  • Hypoventilation with hypoxia
    • Head injury
    • High spinal trauma
    • Severe chest trauma eg: flail chest

• Severe agitation
  • To facilitate interventions/investigations
  • Protect patient/staff

• Intractable pain
  • Severe injuries
  • To facilitate painful procedures

 

Patient optimisation prior to and during intubation

Physiological optimisation

While some patients will require “emergent” (right now) intubation (eg: complete airway obstruction, respiratory arrest), many trauma patients require intubation “urgently” (soon). This gives the team the opportunity to optimise the patient’s physiology as much as possible prior to intubation to prevent hypoxia and hypotension/cardiac arrest with induction.

This can be achieved by:

Preoxygenation 

Ideally with 3 minutes of 100% oxygen via BVM (with an unbroken seal). This may not be possible in many trauma patients. In these cases, the patient should receive oxygen via a non-rebreather mask with an oxygen flow rate of 15L/min +/- with 15L/min via nasal prongs (if tolerated). While this strategy will probably not deliver 100% oxygen, it will provide some preoxygenation.

Blood pressure optimisation 

The ideal blood pressure in patients during the resuscitation phase of trauma care is controversial though in the absence of TBI, a lower blood pressure is usually tolerated. See: Fluid resuscitation and BP in trauma – controversy.

Many induction agents will lower blood pressure and can lead to cardiac arrest in patients who are haemodynamically unstable. Even “safe” agents such as ketamine and etomidate can be haemodynamically detrimental in extremely shocked patients. Patients should ideally be resuscitated with early use of blood products if hypovolaemic prior to intubation.

External haemorrhage should be controlled and other adjuncts (eg: pelvic binding) should be utilised prior to intubation.

 

Airway assessment, checklists, algorithms

Prior to intubation, an assessment of the patient’s airway should be undertaken to quantify the risk of a potential difficult airway

Predictors of a difficult airway include the “LEMON” score¹

LEMON

A higher score can be predictive of a more difficult airway. Expert assistance should be requested if available.

* it might be difficult to perform a [tooltip tip=”measures the distance from base of tongue to roof of mouth – give an indication of how much space there is in the mouth”]mallampati[/tooltip] score in a trauma patient that is obtunded or has significant facial trauma. Neck mobility will be limited in many trauma patients due to concerns regarding cervical spine injuries.

 

Checklists

The use of a standardised airway checklist is encouraged

 

Airway algorithms

An airway plan should be clearly stated and in the case of “can’t intubate, can’t ventilate” a standard failed airway algorithm followed.

Note that some patients with severe facial or laryngeal trauma may have a “surgically inevitable airway” – if these patients require intubation and are hypoxic despite oxygenation and airway manoeuvres, they may need to rapidly progress to a surgical airway.

 

See – Cricothyroidotomy

 

Patient positioning

The ideal intubating position is with the patient ramped to position where the ear is in line with the sternal notch with the head raise in the so called “sniffing position”.

Many trauma patients have a potential cervical spine injury, so this position has the potential to cause secondary spinal cord injury.

In patients with a concern for cervical spine injury who are to be intubated, the collar should be removed and manual inline stabilisation (MILS) utilised with minimal neck movement occuring during intubation. This is the ideal situation however, and must be balanced with the risk of hypoxia from prolonged attempts at intubation in a patient who is in a suboptimal position for intubation.

 

Apnoeic oxygenation

To facilitate “apnoeic oxygenation”, 15 L/m of oxygen is delivered via nasal prongs and moves via a concentration gradient from the nasopharynx to the alveoli.

Several studies have shown that this can increase safe apnoeic time during intubation.² This is particularly important in the patient with [tooltip tip=”traumatic brain injury”]TBI[/tooltip] where even one episode of hypoxia can increase mortality

Note that it will only work if the patient has a patent nasopharynx so will have limited utility in patients with mid-face or nasal fractures.

 

 

Cricoid pressure vs external laryngeal manipulation

The use of cricoid pressure during intubation was considered to be the standard of care for many years. It was theorised that this manoeuvrer would prevent aspiration of gastric contents by occluding the oesophagus. Subsequent studies have shown that it probably has little effect in preventing aspiration and can significantly impair intubation views.³ For this reason, it has largely been abandoned.

In contrast, use of external laryngeal manipulation (eg: “BURP” backward, upward, rightward pressure) can be useful in obtaining a good view of the vocal cords and should be utilised when required.

 

Intubation drugs

 

Induction agents

 

 

Ketamine

Dose: 0.5-2mg/kg

In many centres, ketamine is considered the induction agent of choice in shocked trauma patients.⁴

In patients with TBI, concerns regarding raising ICP have been largely dismissed. However, it should be recognised that ketamine can cause a transient increase in blood pressure and can increase cerebral metabolic rate.

 

Etomidate

Dose – 0.3mg/kg

Another useful agent in shocked patients as it has little effect on BP.

There is ongoing debate regarding the potential for latent adrenal suppression and increased mortality.^5,6

 

Propofol

Dose – 0.15-3mg/kg (beware of higher doses in shocked trauma patients)

Has neuroprotective properties

Causes hypotension and myocardial depression – use with caution in shocked patients, balance risk/benefit in patients with TBI

 

Thiopentone

Dose – 0.15-3 mg/kg (beware of higher doses in shocked trauma patients)

A barbiturate induction agent still used in some centres.

Has neuroprotective properties

Causes hypotension and myocardial depression – use with caution in shocked patients, balance risk/benefit in patients with TBI

 

 

Muscle relaxants

 

There is some debate in the literature at present regarding the use of suxamethonium vs rocuronium as a paralytic agent in RSI.⁷

The choice of paralytic will largely be determined by departmental and individual experience.

 

Suxamethonium

Dose: 1.5-2mg/kg

Onset of effect: 45-60 seconds

Duration of action: 3-10 minutes

• A depolarising muscle relaxant
• May increase ICP
• Carries a risk of malignant hyperthermia in susceptible patients
• Risk of anaphylaxis
• Use with care in patients with crush injury – can cause a spike in potassium
• Contraindicated after 24h in patients with severe burns or after 48h in patients with spinal cord injury

 

 

Rocuronium

Dose: 1.2mg/kg (intubating dose)

Onset of effect: 45-60 seconds

Duration of action: 30-90 minutes

• A non-depolarising muscle relaxant.
• No effect on ICP, does not increase potassium, doesn’t cause malignant hyperthermia
• Risk of anaphylaxis

 

 

 

Post intubation cares

 

Medication

Paralysis

In the immediate phase following intubation, paralytic agents are usually continued to facilitate procedures, investigations and transfer.

The choice of paralytic agent will largely be driven by departmental preferences. Options include: rocuronium, pancuronium, vecuronium and atracurium.

 

Sedation/analgesia

Most patients that are intubated will require ongoing treatment with sedation and analgesia.

This is especially important if the patient has been intubated with rocuronium (long duration of action) or is to have ongoing long acting paralysis administered in order to prevent paralysed awareness.

 

Infusions (eg: propofol) are often utilised to provide ongoing sedation.

 

It should be noted that analgesia in the post intubation phase is extremely important as endotracheal intubation is extremely uncomfortable and the patient is often subjected to painful procedures after intubation.

Propofol has no analgesic effect so the addition of analgesia (eg: boluses or infusions of morphine or ketamine) should be provided as well as sedation.

 

Ventilation

Ventilation settings should be utilised to prevent barotrauma and optimise haemodynamics. A neuroprotective strategy is important for patients with TBI

See: Severe TBI neuroprotection

Continuous waveform capnography is the standard of care following intubation.

 

Gastric tube

Patients that are intubated should have a nasogastric or orogastric tube placed in order drain gastric contents and decrease intraabdominal pressure.

In patients with facial fractures or suspected base of skull fracture, an orogastric tube should be placed in preference to a nasogastric tube (to prevent further disruption of facial fractures or the dreaded intracranial nasogastric placement).

 

IDC

An IDC should be placed in all intubated trauma patients.

In patients with pelvis injury – extreme care should be taken to avoid worsening urethral trauma see: suspected urethral trauma

 

 

Intubation in patient with traumatic brain injury

 

 

It is also important to avoid spikes of increased intracranial pressure. These patients are particularly susceptible to the reflex sympathetic response to intubation.

 

Strategies to prevent blood pressure fluctuations in patients with TBI

• Resuscitate patient prior to intubation
  • Early use of blood products for traumatic hypotension
  • Aim for a SBP of around 110mmHg (some recent studies suggest even high SPB aims of 120mmHg)⁹
• Consider pre-treatment with fentanyl to prevent the hypertensive response to intubation
  • Administer around 3 minutes prior to intubation
  • Note: the literature suggests a 2-5mcg/kg pre-treatment dose of fentanyl. This can equate to a very large dose: use with caution especially if patient is shocked.
• Minimise laryngeal instrumentation
  • ie: the most experienced intubator should perform laryngoscopy
• Intubate patient with head elevated to 30 degrees (while maintaining cervical spine alignment)
• Choose an induction agent with minimal hypotensive potential
  • Ketamine or etomidate would be the induction agents of choice
  • Agents such as propofol or thiopentone while neuroprotective, should be with caution, and in lower than standard doses
• Careful BP monitoring during intubation is essential.
  • A “push dose” pressor should be available (eg: metaraminol or adrenaline) in case of peri/post intubation hypotension and used (with caution) if indicated.

 

 

 

 

 

 

References:

 

https://www.east.org/education/practice-management-guidelines/emergency-tracheal-intubation-immediately-following-traumatic-injury

 

 

 

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