Drugs to Aid Intubation

Pretreatment typically includes

If time permits, patients should be placed on 100% oxygen for 3 to 5 minutes; this measure may maintain satisfactory oxygenation in previously healthy patients for up to 8 minutes. Noninvasive ventilation (NIV) or high-flow nasal cannula (HFNC) can be used to aid preoxygenation (1 General references Pulseless and apneic or severely obtunded patients can (and should) be intubated without pharmacologic assistance. Other patients are given sedating and paralytic drugs to minimize discomfort... read more ). Even in apneic patients, such preoxygenation has been shown to improve arterial oxygen saturation and prolong the period of safe apneic time (2 General references Pulseless and apneic or severely obtunded patients can (and should) be intubated without pharmacologic assistance. Other patients are given sedating and paralytic drugs to minimize discomfort... read more ). However, oxygen demand and safe apnea times are very dependent on pulse rate, pulmonary function, red blood cell count, and numerous other metabolic factors.

Laryngoscopy can stimulate coughing and causes a sympathetic-mediated pressor response with an increase in heart rate, blood pressure, and possibly intracranial pressure. When time permits, some practitioners give lidocaine 1.5 mg/kg IV 1 to 2 minutes before sedation and paralysis to decrease coughing and possibly to decrease the sympathetic-mediated pressor response, although the evidence is mixed. Fentanyl (eg, 3 to 5 mcg/kg IV), also given 1 to 2 minutes prior to intubation, may also blunt the increase sympathetic-mediated pressor response.

Children and adolescents often have a vagal response (marked bradycardia) in response to intubation and are given atropine 0.02 mg/kg IV (minimum: 0.1 mg in infants, 0.5 mg in children and adolescents) at the same time.

Some physicians include a small dose of a neuromuscular blocker, such as vecuronium 0.01 mg/kg IV, in patients > 4 years to prevent muscle fasciculations caused by full doses of succinylcholine. Fasciculations may result in muscle pain on awakening and cause transient hyperkalemia; however, the actual benefit of such pretreatment is unclear.

Laryngoscopy and intubation are uncomfortable; in conscious patients, a short-acting IV drug with sedative or combined sedative and analgesic properties is mandatory.

Etomidate 0.3 mg/kg IV, a nonbarbiturate hypnotic, may be the preferred drug.

Fentanyl 5 mcg/kg IV (2 to 5 mcg/kg in children) also works well and causes no cardiovascular depression. NOTE: This dose is higher than the analgesic dose and needs to be reduced if used in combination with a sedative-hypnotic, eg, propofol or etomidate. Fentanyl is an opioid and thus has analgesic as well as sedative properties. However, at higher doses, chest wall rigidity may occur.

Ketamine 1 to 2 mg/kg IV is a dissociative anesthetic with cardiostimulatory properties. It is generally safe but may cause hallucinations or bizarre behavior on awakening. These adverse effects can be managed with low doses of prophylactic benzodiazepines.

Propofol, a sedative and amnesic, is commonly used in induction at doses of 1.5 to 3 mg/kg IV but can cause cardiovascular depression leading to hypotension.

Thiopental 3 to 4 mg/kg IV and methohexital 1 to 2 mg/kg IV tend to cause hypotension and are used less often.

Skeletal muscle relaxation with an IV neuromuscular blocker markedly facilitates intubation.

Succinylcholine (1.5 mg/kg IV, 2.0 mg/kg for infants), a depolarizing neuromuscular blocker, has the most rapid onset (30 seconds to 1 minute) and shortest duration (3 to 5 minutes). It should be avoided in patients with burns, muscle crush injuries > 1 to 2 days old, spinal cord injury, neuromuscular disease, renal failure, or possibly penetrating eye injury. About 1/15,000 children (and fewer adults) have a genetic susceptibility to malignant hyperthermia Malignant Hyperthermia Malignant hyperthermia is a life-threatening elevation in body temperature usually resulting from a hypermetabolic response to concurrent use of a depolarizing muscle relaxant and a potent,... read more due to succinylcholine. Succinylcholine should always be given with atropine in children because pronounced bradycardia may occur.

Alternative nondepolarizing neuromuscular blockers have longer duration of action (> 30 minutes) but also have slower onset unless used in high doses that prolong paralysis significantly. Drugs include atracurium 0.5 mg/kg, mivacurium 0.15 mg/kg, rocuronium 1.0 mg/kg, and vecuronium 0.1 to 0.2 mg/kg injected over 60 seconds.

Intubation of an awake patient (typically not done in children) requires anesthesia of the nose and pharynx. A commercial aerosol preparation of benzocaine, tetracaine, butyl aminobenzoate (butamben), and benzalkonium is commonly used. Alternatively, 4% lidocaine can be nebulized and inhaled via face mask. Caution is needed when benzocaine is used because it can cause methemoglobinemia.

Appropriate medications should also be immediately available for post-intubation sedation and analgesia. Combinations of opioids and benzodiazepines (eg, fentanyl and midazolam) can be quickly administered as bolus doses. Continuous infusion of sedatives such as propofol or dexmedetomidine can also be used. After initial intubation and resuscitation, clinical practice guidelines recommend the use of light sedation (rather than deep sedation) in adult critically ill patients and recommend the use of propofol or dexmedetomidine over benzodiazepines. Benzodiazepines have a higher incidence of delirium (3 General references Pulseless and apneic or severely obtunded patients can (and should) be intubated without pharmacologic assistance. Other patients are given sedating and paralytic drugs to minimize discomfort... read more ).