Exam I: Full Stomach Flashcards
What percent mortality occurs with aspiration?
5%
What reasons lead to higher risk of aspiration?
- Gi obstruction
- NPO failure
- Alc
- Trauma
- Medications that cause delayed gastric emptying ( narcotics)
- Extremes of age
- Pregnancy
- Parkinson’s disease level moreso w/ levodopa
9 emergency surgery (3 - 4x) - Night surgery (6x)
- Light or inadequate anesthesia
- ASA 4 or 5
- High spinal (can cause hypotension, or lose control of airway, vomiting with NMB)
- Difficult airway
What are some physiologic
Risk factors for aspiration?
l. Increased Justin fluid volume (gfv)
2. Delayed gastric emryptying
3. Impaired protective physiologic mechanisms (LES & UES)
4. Loss of airway protective reflexes
What are some risk factors that qualify as “full stomach”?
- Intestinal Obstruction (SBO)
- Drugs (opioids, anticholinergics)
- Pregnancy (esp. 3rd)
- Diabetes (neuropathy) central vs peripheral
- Sympathetic stimulation (stress response) trauma, acute pain, anxiety
What are determinants of morbidity and mortality with regard to aspiration?
- PH (2.5)
- GFV aspirated directly (more is likely worse - 25cc?)
- Increased bacterial density
- Solid material (particulate)
BLOOD and DIGESTIVE ENZYMES do not appear to induce chemical pneumonitis
What variables are important to consider perioperatively to optimize the “‘full-stomach” patient?
- Type of anesthetic
- Pt comorbidities (ASA 3 or 4)
- Characteristics of aspirate
- NPO Status (recent meal, drink, alcohol)
- Gastric Insufflation (mask ventilation)
- Acid Hypersecretion (Hypoglycemia, alcohol, gastric secretion)
What forms the border between the stomach and the esophagus?
Lower Esophageal Sphincter
How do we calculate the Barrier Pressure?
BP = LES Pr. - Gastric Pr (IGP)
What is the normal gastric pressure?
<7 mmHg
What is the purpose of holding cricoid pressure?
Prevent the passive regurgitation of gastric contents
______ hernia is often associated with decreased LES tone (and therefore increased risk of aspiration).
Hiatal
Factors that increase Lower esophageal Barrier pressure:
- Dopaminergic antagonist
- Metoclopramide
- Beta Adrenergic Antagonist
- GI cholinergic agonists
What muscle acts as the functional Upper Esophageal Sphincter?
Cricopharyngeus Muscle
What anesthetic agent does NOT decrease UES tone in low doses?
Ketamine
What are three challenges full stomach patients present?
- Prevention of gastric regurgitation
- Prevention of pulmonary aspiration
- Appropriate airway management
4 criteria for creating “safe anesthetic management plan” for reducing pulmonary aspiration in full stomach patients:
- ID patients at risk for gastric regurgitation and pulmonary aspiration
- Utilizing NPO guidelines
- Implementing prophylactic pharmacological therapies
- Applying appropriate airway management techniques that may reduce pulmonary aspiration risk
Presence of bilious secretions or particular matter in the tracheobronchial tree
Aspiration
Time frame for aspiration risk
Pre-op - 2 hours Post op
3 ways of diagnosing aspiration
- Direct vision
- Bronchoscope
- New infiltrates from pre-op X-ray
Most risk for aspiration occurs during ____
Indication
however risk still remains at emergence
Clinically, during the first two hours after aspiration occurs, by much should we expect SpO2 to decline?
10%
What is an approximate aspiration mortality rate according to cited study in lecture?
5%
What approximate % of patients may appear asymptomatic the following 2 hours after aspiration?
2/3
Better Health Group
According to aspiration study, what fraction of patients ended up on the ventilator?
1/3
Poor Health Group
According to aspiration study, if patients ended up ventilator for >24 hours, what was the mortality rate?
50%
Risks of High Aspiration: might expect/can be planned for
- GI Obstruction
- NPO Failure
- ALC
- Trauma (decreased PS tone = delayed gastric emptying)
- Rx that delay GE (gastric emptying) = narcotics (opioid receptors present in GI tract)
- Extremes of age
- Pregnant (particularly 3rd tri. & those in labor)
- Parkinson’s
Trauma patients will have increased/decreased ICP.
Increased
Why do elderly have higher risk of Aspiration?
Attenuated cough & gag reflex
Reason Parkinson’s causes increased aspiration risk?
Delayed gastric emptying
worse if on Levodopa: increases Dopamine levels —> slows GI motility & decreases LES tone
Risks for higher aspiration: not NOT expect/unplanned for
- Emergency surgery
- PM surgery
- Light/Inadequate Anesthsia
- ASA 3+
- DA
- High Spinal
Why is a high spinal associated with increased aspiration risk?
- Impaired cough reflex
- Difficulty Swallowing
- Vomiting associated with sympathetic blockade - Induced hTN (Iatrogenic = something we cause)
Physiologic risk factors for aspiration in the peri operative environment
- Increased GFV (gastric fluid volume)
- DGE (Delayed gastric emptying)
- Impaired protective physiologic mechanisms (LES & UES tone)
- Loss of Airway protective reflexes
these are the actual problems that increase risk of aspiration, as opposed to the disease processes (Neurological, Neuromuscular, Opioids, etc.) that cause the problems