Pharmacology for Airway Management

ouseout=”window.status=”; return true;”>2 In routine anesthetic practice, in the elective case, the most commonly used IV anesthetics are propofol and sodium thiopental. Muscle paralysis improves intubating conditions by causing the relaxation of head and neck musculature and preventing the patient’s reflexive movements during direct laryngoscopy. Paralysis is frequently obtained with succinylcholine, which has rapid onset and a brief duration of action. In cases where succinylcholine is contraindicated or avoidance of its side effects is desired (Table 7-4), a nondepolarizing neuromuscular blocker such as rocuronium or vecuronium is often used.3 It should be noted that neuromuscular blockade is not always used in preparation for perioperative airway management —such medication is not used during any awake airway management interventions because continued spontaneous respiration is desired, and avoiding use of neuromuscular blockade may be appropriate in certain cases where overall pati”window.status=this.title; return true;” onmouseout=”window.status=”; return true;”>Table 7-1).1 This helps decrease the anxiety and fear commonly reported before surgical procedures. Oxygen is then provided to help maintain necessary blood oxygen content for homeostasis during the expected period of apnea that occurs after administration of intravenous (IV) general anesthetic agents (Table 7-2) and muscle relaxants (Table 7-3), which are provided to render a patient unconscious and paralyzed, respectively, for the planned airway intervention. Note that the anesthetic must be administered before the muscle relaxant so as to avoid the patient experiencing total paralysis while awake. The combination of anesthesia and paralysis serves an important role in optimization of conditions for intubation—movement is decreased, the patient is amnestic to the event, the vocal cords are relaxed and open, and the cough and gag reflexes are diminished.<A onclick="if (window.scroll_to_id) { scroll_to_id(event,'R2-7'); return false; }" onmouseover="window.status=this.title; return true;" onmouseout="window.status=''; return true;" title=2 class=LK href="#R2-7" name=to-R2-7 xpath="/CT{06b9ee1beed59419a70a2b44a923a9a919e6aa0a05fb19eaab5f1460e4f238153790f71a074c58e1cc7452a8056df2a4}/ID(R2-7)" (Table 7-4), a nondepolarizing neuromuscular blocker such as rocuronium or vecuronium is often used.3 It should be noted that neuromuscular blockade is not always used in preparation for perioperative airway management —such medication is not used during any awake airway management interventions because continued spontaneous respiration is desired, and avoiding use of neuromuscular blockade may be appropriate in certain cases where overall patient outcome might be jeopardized with its use (eg, procedures where motor function is to be monitored or patients with myasthenia gravis).4


As with adults, optimal airway conditions are sought in children undergoing surgery (see Chapter 40). This is frequently carried out not with IV medications but rather with inhalational anesthetic gases. Sevoflurane is the most commonly used agent for inhaled induction of anesthesia because of its rapid onset and comparatively less pungent and irritating characteristics. In either adult or pediatric patients, it is important to be mindful of the expected alterations in hemodynamics and respiration after administration of sedatives, analgesics, and general anesthetics.5

Emergent airway management situations may require different medications from those used in elective cases. In situations requiring emergent intubation of a conscious patient, IV hypnotics are routinely administered to render a patient unconscious, as they are in a controlled elective situation. However, attention must be paid to the overall presentation of the patient requiring immediate airway intervention. In hemodynamically stable patients with presumed euvolemia, both propofol and sod2a8056df2a4}/ID(R1-7)” title=”1″ onmouseover=”window.status=this.title; return true;” onmouseout=”window.status=”; return true;”>1








Agent


IV Dose (mg/kg)a


Time to Onset (s)


Duration of Action afteo_id(event,’R2-7′); return false; }” xpath=”/CT{06b9ee1beed59419a70a2b44a923a9a919e6aa0a05fb19eaab5f1460e4f238153790f71a074c58e1cc7452a8056df2a4}/ID(R2-7)” title=”2″ onmouseover=”window.status=this.title; return true;” onmouseout=”window.status=”; return true;”>2 The patient in cardiac arrest likewise requires no pharmacologic intervention in order to place the endotracheal tube.









Table 7-1 Agents Used for Preoperative or Preprocedural Sedation/Analgesia in Adults1























Agent


Dose


Effect


Midazolam


0.5-2 mg IV


Anxiolysis, amnesia


Diazepam


2.5-5 mg IV


Anxiolysis


Fentanyl


25-100 mcg IV


Sedation, analgesia


Morphine


2.5-5 mg IV


Sedation, analgesia






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May 26, 2016 | Posted by in CRITICAL CARE | Comments Off on Pharmacology for Airway Management

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Table 7-2 IV General Anesthetic Agents for Induction of Anesthesia1