Airway Management II: Lecture 2 - Full Stomach Patient

Question 1

What is the definition of Pulmonary Aspiration?

Answer 1

The presence of bilious secretions of particulate matter in the tracheobronchial tree.

Question 2

What are the risk factors of Pulmonary Aspiration?

Answer 2

• ↑ Gastric Fluid Volume (GFV) w/ either acidic pH, ↑ bacterial count, or solid material
• ↓ gastric emptying
• Impaired protective physiologic mechanisms (incl. ↓ LES and UES pressure)
• Loss of protective airway reflexes (laryngeal-pharyngeal)

Question 3

What percentage of normal subjects aspirate during sleep?

Answer 3

45%

Question 4

What percentage of aspiration occurs during anesthesia?

Answer 4

• 50% occur during induction (prior to DL and intubation)
• 29% during intubation
• Likely to be missed and therefore underreported when it is a little bit

Question 5

What are some risk factors for pulmonary aspiration?

Answer 5

• Extremes of age
• Altered consciousness
• Inadequate NPO
• Pregnant
• Trauma
• Medications (i.e. narcotics)
• Diabetes (diabetic gastroparesis)
• Morbidly Obese
• Stress and acute pain
• ↑ ICP
• Neuromuscular disorders
• Surgery specific risk (esophageal, upper abdominal, emergency laparoscopic surgeries)
• Presenting w/ comorbidities (ASA III, IV and V)
• Emergency surgery
• Difficult airway
• Regional anesthesia (due to Fentanyl and Versed administration)
• Neuraxial can hit the LES

Question 6

What are the main objectives in managing a full stomach patient?

Answer 6

Reduce aspiration risk through identification (risk factors), fasting guidelines, pharmacologic prophylaxis, and airway management.

Question 7

What is the primary concern in a full stomach patient?

Answer 7

Pulmonary aspiration of gastric contents.

Question 8

Who is at risk for pulmonary aspiration?

Answer 8

Patients with improper NPO status or delayed gastric emptying despite fasting.

Question 9

What factors can delay gastric emptying?

Answer 9

• Anxiety
• Diabetes

Question 10

What does NPO stand for?

Answer 10

NPO stands for ‘nil per os’, a Latin phrase meaning ‘nothing by mouth.’

Question 11

What is the fasting time for clear liquids?

Answer 11

2 hours. T1/2 = 12 minutes. Examples: water, fruit juices w/o pulp, carbonated beverages, clear tea, black coffee

Question 12

How long after breast milk must a patient fast?

Answer 12

4 hours. T1/2 = 25 minutes

Question 13

What’s the fasting requirement for infant formula or light meals?

Answer 13

6 hours.

Question 14

What is the minimum fasting time after fatty foods or meat?

Answer 14

8 hours or more.

Question 15

What are the anesthetic goals in a full stomach patient?

Answer 15

• Minimize gastric content
• Reduce gastroesophageal reflux
• Prevent perioperative pulmonary aspiration

Question 16

What strategies support the anesthetic goals in a full stomach patient?

Answer 16

• Pharmacologic therapy
• Gastric emptying
• Facilitation of gastric emptying or drainage
• Maintaining LES tone

Question 17

What is the critical gastric fluid volume and pH?

Answer 17

Gastric fluid volume: 0.4mL/kg and pH < 2.5

Question 18

What volume of vomitus is a concern?

Answer 18

25-50 mL

Question 19

What causes Delayed Gastric Emptying?

Answer 19

• Intestinal obstruction
• Drugs (opioids, anticholinergics)
• Pregnancy
• Obesity
• Diabetes
• PUD
• Trauma
• Sympathetic stimulation (acute pain, anxiety, stress)

Question 20

What is the LES?

Answer 20

Border between stomach and esophagus.

Question 21

What are some facts about the LES?

Answer 21

• Barrier Pressure = LES pressure – gastric pressure
• Normal gastric pressure: < 7 mmHg
• Normal resting LES pressure: 15-25 mmHg higher than intragastric pressure
• LES tone reduction is the major problem in pts w/ gastroesophageal reflux during anesthesia and disease states

Question 22

What is the UES?

Answer 22

Cricopharyngeus muscle, prevents aspiration by sealing off the upper esophagus from the hypopharynx.

Question 23

What physical actions decrease LES tone?

Answer 23

• Cricoid pressure (due to pharyngeal-mediated reflex relaxing LES)
• Laryngoscopy

Question 24

What drugs decrease LES tone?

Answer 24

• Anticholinergics
• Benzodiazepines
• Dopamine
• Sodium nitroprusside
• Ganglion blockers
• Thiopental
• TCAs
• Β-adrenergic stimulants
• Opioids
• Propofol

Question 25

What drugs increase LES tone?

Answer 25

* Antiemetics * Cholinergic drugs * Succinylcholine * Pancuronium * Reglan * Domperidone * Edrophonium, neostigmine * Metoprolol * α-adrenergic stimulants * Antacids

Question 26

What are the Laryngeal-Pharyngeal Protective Reflexes?

Answer 26

* Apnea w/ laryngospasm * Coughing * Exhalation * Spasmodic panting

Question 27

What can impair L-P function secondary to altered consciousness?

Answer 27

* CNS disorders * Cerebrovascular injuries * Head trauma * Alcohol * Neuromuscular disorders * Anesthetic agents that ↓ UES tone

Question 28

What is the goal of airway management in full stomach patients?

Answer 28

Prevent aspiration and ensure safe intubation.

Question 29

What are two key techniques for airway management in full stomach patients?

Answer 29

* Awake fiberoptic intubation * Rapid sequence induction (RSI) following preoxygenation and cricoid pressure (CP)

Question 30

Is LMA recommended in full stomach patients?

Answer 30

Generally no, but second-generation LMA may be used as a temporizing measure.

Question 31

What other devices can be used in full stomach patients?

Answer 31

* Esophageal-Tracheal Combitube * Awake intubation

Question 32

Is an awake intubation an option for a patient with a full stomach?

Answer 32

Yes, a full stomach patient with a difficult airway warrants an awake intubation.

Question 33

What is the standard force for cricoid pressure?

Answer 33

44 N (~10 lbs).

Question 34

Is CP at 30N adequate?

Answer 34

Anatomic studies suggest CP of 30 N is adequate and should reduce risk of esophageal rupture. Single-handed or double-handed CP

Question 35

What is the cricoid cartilage?

Answer 35

Signet ring shaped complete ring of cartilage. Attached superiorly to the thyroid cartilage Attached inferiorly to the first tracheal ring

Question 36

How can continued vomiting with CP lead to death?

Answer 36

Pulmonary aspiration, ruptured esophagus.

Question 37

Why is cricoid pressure applied?

Answer 37

To occlude the esophagus and prevent regurgitation.

Question 38

What risk is associated with vomiting during cricoid pressure?

Answer 38

Esophageal rupture and pulmonary aspiration.

Question 39

What is the objective of an RSI?

Answer 39

Minimize time interval between loss of consciousness and endotracheal intubation.

Question 40

What are features of an RSI?

Answer 40

* Preoxygenation w/ 100% oxygen * Application of CP * Administration of predetermined induction dose * Avoidance of PPV until the airway is secured w/ cuffed ETT

Question 41

What is a modified RSI?

Answer 41

An RSI w/ the addition of mask ventilation to ensure ability to MV and prevent hypoxia/hypercarbia; Any deviation from a true RSI

Question 42

What distinguishes RSI from standard induction?

Answer 42

RSI avoids mask ventilation and uses cricoid pressure with a rapid-acting agent.

Question 43

When is cricoid pressure released during RSI?

Answer 43

After ETT placement is confirmed.

Question 44

What do you avoid in Awake Intubation vs RSI?

Answer 44

* Loss of protective reflexes * The failure of CP to prevent pulmonary aspiration * Failed endotracheal intubation leading to hypoxia and brain death * Cardiovascular collapse

Question 45

What is the advantage of an Awake Intubation?

Answer 45

* Maintenance of protective airway reflexes * Uncompromised airway exchange and oxygenation * Maintenance of normal muscle tone

Question 46

What is necessary for Standard Induction?

Answer 46

* Adequate preoxygenation * Induction agent of choice (cricoid pressure not necessary) * Ensure ability to MV * MR of choice * Confirmation of ETT placement

Question 47

What is necessary for RSI?

Answer 47

* Adequate preoxygenation * Rapid acting induction agent w/ cricoid pressure * Absence of Mask Ventilation * MR w/ Succinylcholine (usually, but may be contraindicated * Cricoid Pressure released after confirmation of ETT placement via auscultation

Question 48

What is the immediate response to suspected aspiration?

Answer 48

* Suction mouth and pharynx * Lower head of bed * Intubate promptly

Question 49

How is oxygenation maintained post-aspiration?

Answer 49

* Supplemental oxygen * CPAP * PEEP

Question 50

Are steroids or prophylactic antibiotics recommended for aspiration pneumonitis?

Answer 50

No.

Question 51

What is required when an Awake Induction or RSI was performed for aspiration risk?

Answer 51

A awake tracheal extubation is also indicated, Pt should be awake, conscious, and appropriately responding to commands prior to extubation, Risk of pulmonary aspiration is a contraindication to deep tracheal extubation

Question 52

What should be considered during emergence?

Answer 52

* Risk of aspiration * Smooth extubation * Adequate airway reflexes

Question 53

What is the Management of Pulmonary Aspiration?

Answer 53

* Suction mouth and pharynx and drop head of bed immediately * Intubate as quickly as possible * Maintain PaO2 ≥ 60 mmHg w/ supplemental oxygen * Bronchoscopy performed to remove obstructing material from lower airways if necessary * Severe bronchospasm treated w/ bronchodilator (inhalation of β-adrenergic bronchodilator, deepened anesthetic with volatile anesthetic) * CPAP if necessary * Mech ventilation w/ PEEP if high levels of CPAP required (> 14 mmHg) * Bronchial lavage? * Prophylactic abx not recommended * Steroids – no role in tx of aspiration pneumonitis

Question 54

What distinguishes Aspiration Pneumonitis from Aspiration Pneumonia?

Answer 54

Aspiration of sterile gastric contents vs colonized oropharyngeal material.