Recognition and management of complications during moderate and deep sedation part 1: respiratory considerations

Abstract

The risk for complications while providing any level of sedation or general anesthesia is greatest when caring for patients having significant medical compromise. It is reassuring that significant untoward events can generally be prevented by careful preoperative assessment, along with attentive intraoperative monitoring and support. Nevertheless, we must be prepared to manage untoward events should they arise. This continuing education article will review respiratory considerations and will be followed by a subsequent article addressing cardiovascular considerations.

Figure 1

Mallampati airway classification., An increase in Mallampati class correlates with increased difficulty in airway management. Class I: complete visualization of uvula, tonsillar pillars, and soft palate. Class II: only partial visualization of the uvula. Class III: only soft palate visible. Class IV: only hard palate visible.

Figure 2

Components of a primary assessment and conditions they reveal.

Figure 3

Positioning of oropharyngeal (A) versus nasopharyngeal (B) airways.

Figure 4

Insertion of supraglottic airways (SGA) and suggested sizes. (A) The tip of the cuff is pressed upward against the hard palate by the index finger, while the middle finger opens the mouth. (Insertion is often facilitated by adding a small volume of air (approximately 5 mL) to the cuff.) (B) The SGA is pressed backward in a smooth movement. Notice that the nondominant hand is used to extend the head. (C) The SGA is advanced until definite resistance is felt. (D) Before the index finger is removed, the nondominant hand presses down on the SGA to prevent dislodgment during removal of the index finger. The cuff is subsequently inflated fully, and outward movement of the tube is often observed during this inflation (courtesy of LMA North America Inc, San Diego, Calif).

Figure 5

The i-gel supraglottic airway.

Figure 6

Suggested minimum devices required for oxygenation and ventilation.

Figure 7

American Dental Society of Anesthesiology airway algorithm. Airway management of the unconscious patient should include the illustrated sequence of interventions.

Figure 8

Patient positioning.

Figure 9

Needle cricothyrotomy. Needle cricothyrotomy can be performed using a 12- to 14-gauge angiocatheter attached to a 3-mL syringe containing 1–2 mL normal saline. (A) Locate the cricothyroid membrane. Palpate the thyroid cartilage (Adam's apple), then the depression at its inferior edge (cricothyroid membrane), and finally the cricoid cartilage inferior to this. (B) Place finger on the cricoid cartilage with the fingernail at the superior edge. Insert the angiocatheter next to the fingernail through the cricothyroid membrane aimed approximately 45° inferiorly. (C) Bubbles will appear in the syringe when the tracheal lumen is entered, and application of negative pressure to the syringe will further confirm catheter placement. (D) Advance the catheter to its hub and then remove the syringe and needle. (E) Attach oxygen source to catheter hub. See text for further explanation (modified from Nagy19).

Figure 10

Attaching a bag-valve device to needle hub. The adapter from a size 3 endotracheal tube will insert directly into the hub of the catheter or one from a size 7.0 endotracheal tube will tightly insert into the barrel of a 3-mL syringe. The bag-valve device is connected to a 100% oxygen source at 10–15 L/min and squeezed 10–15 times per minute to provide oxygen through the cannula.