During swallowing, what is happing in the esophagus and the LES?

The esophagus is CONTRACTING (peristalsis) but the LES which is an extension of the esophageal musculature is actually RELAXED.

When a sphincter is relaxed, the tone ______ and the pressure ______. When a sphincter is constricted, the tone _____ or the pressure _______.

decreases, decreases (relaxed sphincter)

increases, increases (constricted sphincter)

What is the major pathophysiological derangedment in gastric reflux?

A reduction in LES tone or pressure

Name two things that affect the LES

INTRINSIC NERVE PLEXUS and GASTRIN released by the mucosa of the gastric antrum in response to the presence of acid

What in increases the sphincter pressure?

Gastrin

What DECREASES LES tone?

Cricoid pressure

What increases LES tone?

Succinylcholine

LES pressure-Gastric pressure= ?

barrier pressure

Name two conditions that increase LES tone and intragastric pressure?

obesity and pregnancy

Does succs increase the risk of reflux?

It does not appear that it does, UNLESS the LES is incompetent.

Who much can the stomach hold w/out significantly increasing the intragastric pressure?

1.5 liters

 What does peristalsis do?

What does the pyloris to?

Peristalsis moves food stuff forward

Pyloris relaxes allowing expulsion

Name conditions associated with a reduction in gastric empying & therefore high volume states?

obesity

bedridden states

pregnancy

shock

trauma

 pain

It increases gastric emptying for up to 24 hours!

what is the pH of HCL

1-3.5

Mendelson's syndrome states what?

a volume of greater than 0.4ml/kg (some say 25cc) and a pH of less than 2.5 increases the risk for severe pneumonitis

What is the significance of human milk on the digestive system?

Human mild goes through digestion faster=faster emptying.

Names 4 protective airway mechanisms:

1) closure of both the true and false cords (laryngospasm)

2) coughing

3) expiration reflex (sudden opening of the glottis and closure of the false cords)

4) spasmodic panting (rapid opening and closure of the glottis)

What can blunt protective airway reflexes? Which one is the exception?

Opioids can blunt the reflexes

The exception is laryngospasm

*Sooo, premed of pts (elderly especially) can predispose them to a higher risk of aspiration!

Name one way to reduce perioperative risk & what you need to minimize to achieve this.

CONTROL AMT of GASTRIC CONTENT

by:

minimizing intake

(NPO status, clear liquids up to 2 hrs preop)

delayed gastric emptying correlates with the presene of autonomic neuropathy, but not ???

Age, duration of disease HgA1C or peripheral neuropathy

To reduce perioperative risk of aspiration, we can also reduce gastric acidity. But how?

-H2 receptor antagonists (increase the pH of new gastric fluid-but not existing fluid in stomach)

-Proton pump inhibitors ( increase pH; reduce volume)

-Sodium citrate (w/in 1 hr of surgery in 15-30 ml volumes)-(increases gastric pH of fluid already in stomach)

You can also increase motility with prokinetics by using:

-Reglan which increases gastric empying by incrasing peristaltic action, increases LES tone, decrease the pylorus tone and duodenum, does NOTHING to pH

You've placed an OGT or NGT, is your stomach empty?

NO GUARANTEE that your stomach is empty & may impair the function of the UES and LES

How much pressure is used for cricoid pressure?

What happens in the awake pt w/ pressures over 40?

20-44 Newtons of pressure

Coughing and retching

Explain how to apply cricoid pressure. Cricoid pressure by itself can increase the incidence of what?

10 Newtons applied as they lose consciousness and then is increased to 30 Newtons after loss of consciousness.

Tachycardia and hypertension-it can also distort anatomy and make ventilation difficult

What is the best protection against aspiration? What provides NO coverage?

Intubation with a cuffed ETT 

LMA (& mask) provides NO coverage

Splanchnic blood flow is predominantly influenced by what?

Autonomic nervous system

What happens with prolonged sympathetic stimulation of splanchnic blood flow?

There is an initial decrease in blood flow with a gradual return to normal.

Therefore, severe stress can decrease splanchnic blood flow.

Hypoxia, reduced flood flow & inadequate oxygen carrying capacity from anemia or impairment of blood supply leads to what?

Gut ischemia and ischemia of anastomotic suture lines

Hypocapnia significantly ______ splanchnic blood flow while hypercapnea ______ splanchnic blood flow.

Hypocapnia=reduces

Hypercapnea=increases

Post operative anastomotic leaking may be related to anesthesia factors including:

1) Use of prokinetic - VERY BAD IDEA-NEVER USE!

2) Neostigmine increases parasympathetic activity increasing bowel parastalis (controversial whether we should give or not)

Opioids reduce bowel activity through a _______ receptor.

Mu opiod receptor