What is endotracheal intubation?
Endotracheal intubation is a common procedure, but it can be traumatic and quite involved. Intubation requires 10 or more pieces of medical equipment, multiple medications and dozens of steps.
Endotracheal intubation is the procedure to insert a flexible tube into the airway (trachea) through the mouth or the nose. Endotracheal intubation is performed during general anesthesia prior to a surgery or in critically ill patients to assist breathing.
How is endotracheal intubation done?
An anesthetic team performs the endotracheal intubation in three stages with different medications at each stage. Commonly used practice is the rapid sequence intubation protocol, performed as follows:
- Saturation of the lungs with oxygen with an oxygen mask (bag-valve mask) to provide continued oxygen in circulation during the procedure.
- Administration of IV medications to control pain and reflex response to intubation, such as elevated blood pressure and heart rate, intracranial hypertension, coughing and gagging.
- Induction: Administration of a rapid-acting, short-duration anesthetic agent to induce unconsciousness.
- Paralysis: Administration of medications to induce temporary paralysis to prevent muscle contraction during the procedure.
The anesthesiologist inserts the endotracheal tube through the mouth into the airway with the aid of a lighted device (laryngoscope) and secures it in place.
What equipment is required for endotracheal intubation?
The equipment required for endotracheal intubation include the following:
- Laryngoscope: A device made of metal or plastic, with a handle and a curved blade with a light on it. The blade is inserted behind the tongue into the top of the throat to visualize the epiglottis, which is a cartilage at the entrance of the trachea.
- Endotracheal tube: A thin flexible tube with an inflatable balloon (cuff) that is placed inside the airway and inflated to prevent gases leaking past the cuff and allows positive pressure ventilation and prevents material like gastric fluid from entering the trachea.
- Stylet: A thin malleable rod or wire which is placed inside the tube to make insertion easier. The stylet can bend to fit the curvature of the airway and minimize trauma.
- Syringe: To inflate the balloon in the tube.
- Suction catheter: A tube to suction out secretions and prevent aspiration.
- Carbon dioxide detector: A device used to confirm the correct position of the tracheal tube by measuring the exhaled carbon dioxide.
- Oral airway: A device that conforms to the tongue shape is placed in the mouth to keep the airway clear.
- Nasal airway: A device to keep the nasopharyngeal airway clear.
- Bag-valve-mask: A mask used for preoxygenation.
- Nasal cannula: A tube with two prongs that fit into the nostrils, to provide supplemental oxygen.
What medications are required for endotracheal intubation?
The medications used during the three stages of rapid sequence intubation include the following:
Pretreatment medications are administered two to three minutes before intubation. Commonly used pretreatment medications for sedation and pain relief (analgesia) include:
- Other effects: Reduces hypertensive response
- Risks: High doses can cause hypotension and chest wall rigidity
Alternatives to fentanyl include:
- Lidocaine (Xylocaine)
- Lidocaine has local anesthetic properties and can be used locally and intravenously. Lidocaine has an onset time of up to two minutes and lasts for up to 20 minutes.
- Reduces the risk of postoperative sore throat from the tube
- Useful for decreasing hypertensive response in patients with asthma or COPD
- Risks: Hypotension
Other pretreatment medications may include:
A study has reported that intravenous dexamethasone is effective in reducing the incidence of postoperative
Atropine is typically administered for pediatric patients. Atropine has an onset of up to four minutes and lasts for up to four hours.
- Effects: Reduces secretion of saliva and bronchial secretions
- Risks: Increase in heart rate (tachycardia)
Some muscle relaxants may be used in small doses (high doses are paralytic) as pretreatment medications, especially if succinylcholine is used for neuromuscular blockade. Muscle relaxants used as pretreatment medications include:
- Vercuronium (Norcuron)
- Rocuronium (Zemuron)
The selection of the agent for induction of anesthesia is based on the patient’s condition. Commonly used anesthetic agents include:
Etomidate is a rapid-onset anesthetic agent that produces unconsciousness within 30 seconds that lasts for under 10 minutes. Etomidate is useful for patients with multiple trauma and reduced blood pressure (hypotension)
- Does not affect blood dynamics or blood pressure
- No intracranial pressure elevation
- No depression of respiration (apnea)
- No histamine release, which can cause an inflammatory response
- Can cause involuntary muscle jerks (myoclonus)
- Nausea and vomiting
- Pain with injection and no analgesic effect
- Lowers seizure threshold
- Does not suppress reflex response to laryngoscopy
- May suppress adrenal gland activity
Ketamine has both anesthetic and analgesic effects with a rapid onset of under one minute and duration of about 10 minutes.
Advantages: Has bronchodilatory effects which is helpful for patients with lung disease or hypotension
- Increase in intracranial pressure
- Cerebral vasodilation
- Cardiovascular stimulation
- Delirium while coming out of anesthesia
- Increase in sympathetic nervous system activity
Propofol has a rapid onset and short duration of about 15 minutes.
Advantages: Decreases intracranial pressure
Other medications used in the past but no longer used as induction agents for intubation include:
Commonly used paralytic agents include:
Succinylcholine is a neuromuscular blocking drug that has been a choice paralytic agent for decades. It has a rapid onset of one minute and ultrashort activity duration of about six minutes. Succinylcholine is a pregnancy category C medication.
Advantages: Useful for emergency pediatric intubation
- Increase in potassium in the serum
- Malignant hyperthermia (high body temperature)
- Muscle fasciculation (brief spontaneous muscle contraction)
- Cardiac arrest in children with muscular dystrophy
- Abnormal heartbeat (dysrhythmia) with multiple doses
Succinylcholine is not used in conditions such as:
- Burns over a large surface area
- Multisystem trauma with crush injury
- Spinal cord and other nerve injuries
- Muscle tissue damage from crush injury
- Preexisting high potassium levels (hyperkalemia)
Rocuronium has a rapid onset but effects may last up to an hour. Rocuronium is a pregnancy category B medication.
- Does not affect blood circulation dynamics
- Does not release histamines
Risks include: prolonged duration of effects with possible liver damage
Mivacurium is a newer drug being studied for use in rapid sequence intubation. It has an onset of about two and a half minutes and effects that last up to 20 minutes. Mivacurium is a pregnancy category C medication, which means it causes birth defects in animal studies, but may be used in pregnant women if the benefits outweigh the risks.
Pancuronium has an onset of three minutes and duration of action up to 60 minutes. Pancuronium is a pregnancy category C medication, and its use is limited to postintubation paralysis.
- Histamine release
- Increased heart rate
Cis-atracurium has an onset of two to three minutes and effects last up to 75 minutes. Cis-atracurium is a pregnancy category B medication and its use is limited to use in:
- Pediatric patients
- Patients with advanced liver disease
Reversal of paralysis
Sugammadex sodium (Bridion)
Sugammadex sodium is a medication that reverses the effects of longer-acting paralytic agents. Sugammadex sodium is approved by FDA to use for the reversal of: