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INTUBATION MEDICATIONS

Category: Airway

Topic: Advanced Airway Management

Level: Critical Care

22 minute read

Intubation Medications

The process of intubation requires medication in the majority of patients. Two primary terms to know are "induction" and "paralysis."

Induction is the process of inducing unconsciousness, as intubation is a distressing and painful procedure that a patient will fight.
Paralysis eliminates the contraction of the muscles in the jaw, neck, and chest, allowing for easier tube placement and mechanical ventilation.

These drugs are some of the most important in a paramedic's arsenal. Knowing the dosages by heart is an absolute requirement. When these medications are needed taking the time to check dosages can result in complications or even failed intubations.

 

Pre-Medication Agents

These medications are used to increase the rate of success when intubating patients. The most common agents used are atropine and opioids. The use of Lidocaine and small doses of paralytics is less common but is critical in certain situations.

Opioids

Opioids are used for pain relief and their light sedative effect. Fentanyl is the most commonly used opioid in critical care as it has a short duration of action and fewer side effects than morphine. This medication has a one-hour duration of effect and can be re-dosed several times.

  • Fentanyl 1-3mcg/kg IV

Atropine

Atropine is an anticholinergic that inhibits the action of the parasympathetic nervous system. Atropine is useful in intubation as it decreases oral secretions and limits the decrease in heart rate seen with intubation. This effect is most useful in pediatric patients who can have significant heart rate decreases with intubation.

  • Atropine 0.5mg IV once
  • Pediatric dose of 0.02mg/kg (max 0.5mg)

Lidocaine

Less commonly used than the above two medications, Lidocaine is thought to decrease the risk of cardiac arrhythmia and increase intracranial pressure with intubation. Consider its usage in patients with head injuries, blunt chest trauma, or a history of cardiac arrhythmia.

  • Lidocaine 1.5mg/kg IV 3 minutes prior to intubation

Low-Dose Non-Depolarizing Paralytics

When non-depolarizing paralytics such as Rocuronium and Vecuronium are used to facilitate intubation, giving a small (10%) dose 2-4 minutes before intubation is thought to "prime" the synapses for blockade by the higher dose and reduce the time to total paralysis. This priming dose can help prevent desaturations and accumulation of CO2 in critical patients.

When the priming dose is administered before using a depolarizing blocker (succinylcholine,) it can decrease the elevation in intracranial pressure and blood potassium concentration caused by succinylcholine. When using a priming dose with succinylcholine as your intubating paralytic, you will need to double the dose of succinylcholine.

  • Rocuronium 0.1mg/kg IV 2 minutes prior to intubation
  • Note that this is 10% of the usual intubation dose of 0.9-1.2mg/kg

Note, the pre-medication dose of Roc has recently changed to 0.05 from 0.1 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4085266/

 

Induction Agents

Induction agents induce unresponsiveness to allow for the intubation of conscious patients. An induction agent MUST be given prior to administering a paralytic because a paralytic does not affect consciousness. The patient would still be awake and aware, but be unable to move at all. Know the duration of action of your paralytic relative to your induction agent and ensure your patient is sedated for the entire duration of the paralytic's effect. Failure to do so can lead to mental trauma along with lifelong PTSD, anxiety, and depression.

Etomidate

Etomidate is commonly used in the EMS setting due to its minimal effects on heart rate and blood pressure. This medication decreases intracranial pressure and is a good choice for patients with head injuries. Nausea and vomiting are the most common side effects of this medication.

  • Etomidate 0.3mg/kg IV
  • Onset within 10 seconds and duration of 4-10 minutes

Ketamine

Ketamine is a dissociative medication. It does not induce unconsciousness but instead creates an unawareness of what is occurring. Ketamine increases the blood pressure, heart rate, and dilation of the bronchioles, making it an excellent choice for patients in shock or patients with asthma. The most common side effects of ketamine are agitation in low doses (0.5-1 mg/kg) and increased oral secretions.

  • Ketamine 1-2mg/kg IV
  • Onset in 60 seconds and duration of 10 to 20 minutes

Benzodiazepines

Midazolam is commonly used for induction, but its use has fallen out of favor due to issues with hypotension, variable effects, and slower onset time. It is now more commonly used after intubation for short-term sedation while in transit.

  • Midazolam 0.2-0.3mg/kg IV
  • Variable time of onset 15-30 minute duration

Opioids

Opioids have fallen out of favor as an induction medication. They are now routinely given as pre-medication for pain control. While fentanyl can be used to reduce consciousness, dosing varies heavily between individuals and can lead to chest wall rigidity, inhibiting mechanical ventilation.

  • Fentanyl 1-3mcg/kg

Barbituates

Barbituates have also fallen out of favor in the EMS setting. They can be difficult to dose, lead to significant blood pressure drops, and have variable durations of action.

  • Thiopental 3mg/kg IV
  • Onset within 30 seconds and a duration of 5-10 minutes

 

Neuromuscular Blocking Agents

These medications paralyze a patient preventing all muscular movement. Neuromuscular Blocking Agents are necessary when intubating an awake patient. They may be required if an unconscious patient has a clenched jaw, tight neck muscles, or is fighting the ventilator after intubation. Succinylcholine (Sux) is the most commonly used paralytic. Deciding on which neuromuscular blocking agent to use is based on whether a contraindication to succinylcholine exists.

Succinylcholine

The only "depolarizing" neuromuscular blocker, succinylcholine, has near-ideal properties for EMS intubation. It works quickly, is cleared by the body rapidly, can be given without IV access, and is well tolerated in many patients. Its use is limited only by several particular and dangerous interactions.

  • Succinylcholine by IV 1mg/kg in adults, 2mg/kg in children, 3mg/kg in infants.
  • Onset in 30 seconds
  • Duration of 4-6 minutes
  • May be given IM for crash intubation at 4mg/kg with onset in 2 minutes and a duration of 10 - 30 minutes.
  • Complications: Succinylcholine should not be used in patients with burns over 30% of their body, renal failure, or if they have been down for a prolonged period of time as it causes an increase in serum potassium that may be fatal in these conditions. Sux will also elevate the intracranial pressure and may cause bradycardia in pediatric patients.

Rocuronium

Rocuronium is a non-depolarizing neuromuscular blocker. It differs from succinylcholine in that it does not cause changes in potassium balance or increased ICP. The trade-off is that its duration of action is nearly 10x longer than succinylcholine, and its rate of onset is slower.

  • Rocuronium 1mg/kg (max 100mg)
  • Onset in 1-2 minutes
  • Duration of 30 minutes

Vecuronium

Vecuronium is largely identical to rocuronium. It is rarely used in the EMS setting as it has a slower onset and longer duration of action.

  • Vecuronium 0.1mg/kg
  • Onset in 3-5 minutes
  • Duration 45 to 65 minutes

 

Complications

The most common complications of the agents listed above are airway compromise and respiratory depression. These side effects are expected at the doses given for intubation but can become an issue if the patient cannot be intubated even after they are administered. This is the most common "nightmare scenario" in EMS and will be covered in the difficult airway unit.

Anaphylaxis

Many of the agents listed, especially the neuromuscular blocking agents, can lead to anaphylaxis. As with all forms of anaphylaxis, IM epinephrine is the best management for this complication.

Malignant hyperthermia

Malignant hyperthermia is a rare reaction to succinylcholine that occurs due to a genetic abnormality in the receptor within muscles that control the calcium channel. Malignant hyperthermia can also result in an uncontrolled muscle spasm. Watch for the following whenever you are giving succinylcholine.

  • Increasing end-tidal CO2
  • Tachycardia, arrhythmia, or cardiac arrest
  • Muscle rigidity in the jaw, neck, and limbs
  • Increasing temperature

Managing malignant hyperthermia is focused on preventing acidosis, cooling the patient, and providing the antidote Dantrolene.

  • Maximize oxygen delivery
  • Increase minute ventilation by 4x to blow off CO2 and cause an intentional respiratory alkalosis
  • Give 1-2mEg/kg of Sodium Bicarbonate
  • Maximize IV fluid delivery if appropriate
  • Aggressively cool the patient by any means possible
  • Deliver to the nearest facility capable of administering Dantrolene which will terminate the reaction.