BVM Ventilation: Preventing Gastric Insufflation

BVM Ventilation: Preventing Gastric Insufflation

• The 2010 AHA guidelines for BLS CPR no longer recommend the routine use of the crico-thyroid pressure (Sellick maneuver) during BVM ventilation.
• Crico-thyroid pressure may reduce alveolar ventilation more than it prevents air from entering the stomach.
• The best way to avoid gastric inflation during BVM ventilation is to use only enough volume and pressure to produce visible chest rise.
• Crico-thyroid pressure (Sellick Maneuver) can be used to compress the esophagus in unconscious patients and possibly reduce gastric inflation.
• The maneuver can also aid in visualizing the larynx during intubation.
• The cricoid cartilage is located inferior to the thyroid prominence and the cricothyroid membrane.
• To perform the Sellick Maneuver, hold the cricoid between digits and press back against the cervical vertebrae with a force of about 20-30 Newtons.
• The esophageal sphincter opening pressure is about 20-25 cmH2O (approximately 1961 to 2542 Newtons).

Emergency Airway Management: Introduction

• The American Society of Anesthesiology is the primary source for expertise and information on airway management.
• Endotracheal intubation is considered the definitive airway management.
• RCPs (Respiratory Care Practitioners) provide definitive emergency airway support by performing endotracheal intubation.

Indications for Definitive Airway Management

• Secure the airway:
  • Prevent or eliminate upper airway obstruction, especially by collapse of soft tissue.
• Protect the respiratory tract:
  • Prevent aspiration, especially of gastric contents.
  • Indicated when patients' airway protective reflexes are obtunded by medication, injury, or disease.
  • Indicated when the patient requires frequent airway suctioning.
• Provide positive pressure modalities:
  • Ventilatory support (PPV) requires an occlusive airway seal to eliminate pressure leaks.
  • Provide a route for administering oxygen under positive pressure to overcome hypoxemia caused by V/Q imbalance due to atelectasis.
  • Medications can be administered through the endotracheal tube.

Endotracheal Intubation

• Meets all the indications for airway management listed above.
• An essential respiratory care tactile and visual skill that can be mastered by any clinician with adequate practice.
• Evaluating and treating a patient who may require emergency airway management and ventilatory support is an essential RCP skill.

Laryngoscope Equipment

• The laryngoscope is a rigid instrument used to examine the larynx and facilitate tracheal intubation
• It consists of two separate parts: the handle, which contains a battery to power the bulb at the tip of the blade, and the blade itself

Laryngoscope Blades

• Laryngoscope blades come in many different shapes to manage various anatomical and pathological situations
• Clinicians must be familiar with at least two commonly used blade types: curved (Macintosh) and straight (Miller)
• Each blade type has its own advantages and disadvantages

Accessories

• Bougie: a flexible tube used to guide the laryngoscope into the trachea
• Stylet: a thin, rigid rod used to help intubate the trachea

Laryngoscope Blades

• Anesthesia practitioners typically use Macintosh (curved) and Miller (straight) laryngoscope blades for intubation.
• Both blades come in various sizes, and the choice depends on patient anatomy, personal preference, and institutional policy.
• The laryngoscope is designed for right-handed individuals, so it must be held in the left hand; left-handed clinicians must adapt to using it with their left hand.

Macintosh Blade

• Inserted into the right side of the patient's mouth
• The tongue is gently swept to the left and raised anteriorly by the blade's flange
• The blade is curved and has a flange on the right side
• The locking fitting on the left side holds the blade securely in place
• The light bulb is placed above the locking fitting

Miller Blade

• The blade is straight and has a blunt tip
• Never press the blade against the teeth to avoid dental trauma and potential lawsuits.

Laryngoscope Blades

Macintosh (Curved) Blade

• Has a rounded end that causes less trauma to pharyngeal tissues
• Fits into the vallecula, the space between the base of the tongue and the epiglottis
• Lifts the epiglottis passively by pulling tissue folds attached to the tongue base and hyoid bone
• Does not directly lift the epiglottis, unlike the straight blade
• Less likely to stimulate airway protective reflexes when used correctly
• Allows more room for visualization during tube placement, especially in obese patients
• Correctly inserted into the right corner of the patient's mouth
• Flange pushes the tongue toward the left side of the oropharynx as the blade is moved toward the mid-line
• Incorrect insertion down the middle of the mouth can force the intubator's line of sight posteriorly
• Usually, the Macintosh #3 is used for most adult patients, and the #4 is used for large and obese patients

Miller (Straight) Blade

• Used to directly lift the epiglottis and flatten the tongue
• Easier to insert, especially in patients without large maxillary central incisors
• Directly lifts the epiglottis, unlike the curved blade

Equipment for Intubation

• A stylet is a long, malleable rod that facilitates intubation by allowing the flexible endotracheal tube (ETT) to be bent into a curve.
• The stylet is not meant to make the tube rigid, but rather to help guide it into the trachea.
• The stylet is inserted into the tube prior to laryngoscopy and bent to resemble a hockey stick.
• After insertion, the stylet is removed, and the tip should never protrude beyond the distal end of the ETT.
• The stylet is not necessary for routine intubations, only when a curved ETT is required.

The Bougie

• A bougie is a thin, straight, semi-rigid device with a bent tip, used in difficult intubations.
• Only a small percentage of intubations (less than 4%) should be difficult.
• The bougie is carefully advanced into the larynx and through the cords until the tip enters a mainstem bronchus during laryngoscopy.
• An assistant then threads an ETT over the end of the bougie, into the larynx, while the laryngoscope and bougie are held in position.
• Once the ETT is in place, the bougie is removed.

Endotracheal Tubes

• Made of polyvinyl chloride
• Feature a radiopaque line from top to bottom
• Have depth markings in centimeters from the distal end of the tube
• Equipped with a high-volume, low-pressure inflatable balloon
• Have a hole above the beveled distal end known as the Murphy's eye
• Have 15 mm connectors for anesthesia machines, ventilators, or bag-mask devices

Tube Sizing

• Sizes are designated in millimeters of internal diameter
• Sizing is a compromise between minimizing airway trauma during insertion and maximizing ventilation flow and minimizing airway resistance

Insertion Technique

• View the larynx via laryngoscopy
• Introduce the ETT through the right side of the mouth
• Directly observe the tip of the tube passing into the larynx between the abducted, separated cords
• Pass the tube 1 cm past the cords