chapter 15. quiz 3. Anesthesia and Preoperative Care

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Questions and Answers

What is the effect of high sympathetic stimulation on GI tract activity?

It is still unknown

It inhibits GI tract activity (correct)

It increases GI tract activity

It has no effect on GI tract activity

Why are patients often given premedication with a benzodiazepine, such as midazolam, before surgery?

To reduce anxiety and enhance the effect of GABA on GABA-A receptors (correct)

To increase sympathetic stimulation

To inhibit the effect of GABA on GABA-A receptors

To enhance the effect of norepinephrine

What is the effect of midazolam on the migrating motor complex (MMC) in the duodenum?

It eliminates the MMC

It increases the duration of phase III of the MMC

It decreases the duration of phase III of the MMC

shortened the MMC (correct)

What is the relationship between anxiety and GI tract activity?

Higher anxiety decreases GI tract activity Signup and view all the answers

What is one possible explanation for the change in MMC activity caused by midazolam?

The sedative effect of midazolam Signup and view all the answers

What is the consequence of reduced anxiety on GI tract activity?

Decreased inhibition of GI tract activity Signup and view all the answers

What is the order of recovery of bowel function after administration of volatile anesthetics?

Small intestine, stomach, colon Signup and view all the answers

Which of the following volatile anesthetics is associated with greater sympathetic activation during rapid increases in concentration?

Desflurane Signup and view all the answers

What is the effect of volatiles on splanchnic circulation and oxygenation?

Dose-dependent increase Signup and view all the answers

What is the duration of the effect of rapid increases in desflurane concentration on sympathetic and renin-angiotensin system activity?

Short-lived Signup and view all the answers

What is the primary mechanism by which volatile anesthetics affect bowel function?

Depression of spontaneous, electrical, contractile, and propulsive activity Signup and view all the answers

What is the comparison between desflurane and isoflurane in terms of effects on sympathetic and renin-angiotensin system activity?

Desflurane has a significantly greater effect Signup and view all the answers

What is the effect of volatile anesthetics on spontaneous activity?

They depress spontaneous activity Signup and view all the answers

Which of the following is true about the effects of desflurane, isoflurane, and sevoflurane on bowel function?

There is very little difference between their effects on bowel function Signup and view all the answers

What is the relationship between adverse GI effects and the use of volatile anesthetics?

There is no clear-cut relationship between adverse GI effects and the use of volatile anesthetics Signup and view all the answers

during periods of ischemia for resection and anastomosis, reactive hyperemia was better preserved in the patients given?

isoflurane Signup and view all the answers

What is the effect of TIVA on intestinal motility as compared to sevoflurane-remifentanil?

It increased intestinal motility Signup and view all the answers

What was the outcome of a study comparing bowel recovery after open procedures using different anesthetics?

There was no difference in overall recovery and bowel function Signup and view all the answers

What was the difference in inflammatory response among patients receiving TIVA or inhalational anesthesia with sevoflurane and fentanyl in colorectal cancer patients?

There was no difference in inflammatory response Signup and view all the answers

What was the outcome of using TIVA (propofol-remifentanil) compared to sevoflurane-remifentanil in terms of surgeon satisfaction?

higher degree of surgeon dissatisfaction Signup and view all the answers

What is the primary reason nitrous oxide causes bowel distention?

It is more soluble in the blood than nitrogen Signup and view all the answers

What is the correlation between gut distention and the use of nitrous oxide?

The amount of gas already present in the bowel is directly correlated with gut distention Signup and view all the answers

What is the recommended approach when performing lengthy abdominal surgeries?

Avoid using nitrous oxide to prevent bowel distention Signup and view all the answers

What was the outcome of the ENIGMA trial regarding the use of nitrous oxide?

It did not relate the use of nitrous oxide to any significant adverse outcomes Signup and view all the answers

What is the primary reason for avoiding nitrous oxide in certain surgeries?

It can cause bowel distention Signup and view all the answers

What is the potential consequence of the increased intragastric pressure caused by succinylcholine?

It can overcome the tone of the LES and allow reflux of gastric contents Signup and view all the answers

What factors should be considered when assessing the risk of aspiration with succinylcholine?

The patient's body habitus, technical difficulty of intubation, NPO status, and comorbidities Signup and view all the answers

What is the effect of neuromuscular blocking drugs on GI motility?

They have no effect on GI motility Signup and view all the answers

What is the effect of neostigmine on bowel anastomoses?

It increases the risk of dehiscence Signup and view all the answers

Why is sugammadex a more prudent choice for reversal in situations of tenuous bowel anastomoses?

It does not increase parasympathetic activity Signup and view all the answers

What is the goal of anesthetic care in surgical procedures on the GI tract?

To attenuate the stress response, optimize hemodynamic and fluid status, and maintain normothermia Signup and view all the answers

What is the potential benefit of using neostigmine in treating postoperative ileus?

It increases bowel peristalsis Signup and view all the answers

What is the purpose of administering anticholinergic medications, such as glycopyrrolate or atropine, with neostigmine?

To attenuate the bradycardia caused by neostigmine Signup and view all the answers

What is the potential adverse effect of using neostigmine in treating postoperative ileus?

All of the above Signup and view all the answers

What is the primary effect of opioids on the myenteric plexus in the GI tract?

Inhibition of excitatory pathways and inhibits of inhibitory pathways Signup and view all the answers

What is the result of the decreased secretion of acetylcholine and increased release of nitrous oxide in the GI tract?

Decreased propulsive motility Signup and view all the answers

What is the effect of opioid activation on the submucosal plexus?

Decreased nutrient secretion and increased fluid absorption Signup and view all the answers

What is the consequence of the combined effects of opioids on the myenteric and submucosal plexuses?

Constipation Signup and view all the answers

What is the mechanism by which opioids reduce GI motility?

Activation of peripheral mu-receptors Signup and view all the answers

What is the effect of opioids on the ileocecal valve and internal anal sphincters?

Increased tone Signup and view all the answers

What is the effect of naloxone on the gut motility inhibition caused by opioids?

It reverses the analgesic effect of opioids Signup and view all the answers

What is the advantage of methylnaltrexone over naloxone?

It is a peripheral mu-opioid receptor antagonist that does not cross the blood-brain barrier Signup and view all the answers

What is the result of using metoclopramide, neostigmine, and other prokinetic agents in treating opioid-induced constipation?

They have shown some success in alleviating opioid-induced constipation Signup and view all the answers

What is the potential benefit of switching from one opioid to another in treating opioid-induced constipation?

It can alleviate opioid-induced constipation Signup and view all the answers

What is the result of combining opioids with enteral opioid receptor antagonists in treating opioid-induced constipation?

It can alleviate opioid-induced constipation Signup and view all the answers

What is the limitation of methylnaltrexone and alvimopan in treating opioid-induced constipation?

Their long-term efficacy and safety have not been clearly established Signup and view all the answers

What is the primary factor that initiates postoperative ileus?

Manipulation of the intestines Signup and view all the answers

What is the definition of postoperative ileus?

A transient cessation of coordinated bowel motility after surgical intervention Signup and view all the answers

What is the result of surgical manipulation of the bowel during open abdominal procedures?

A degree of trauma that sets in motion the whole process of postoperative ileus Signup and view all the answers

What contributes to postoperative ileus in addition to manipulation of the intestines?

Immobility, electrolyte imbalance, and intestinal wall swelling Signup and view all the answers

What is the main effect of surgical procedure on GI physiology and function?

Predisposes to postoperative ileus Signup and view all the answers

What is the primary cause of the early neurogenic phase of postoperative ileus?

Manipulation of the intestine during surgery Signup and view all the answers

What is the outcome of the inflammatory cascade in the gut after surgical manipulation?

Increased permeability and translocation of intraluminal bacteria Signup and view all the answers

How long does the late inflammatory phase of postoperative ileus typically last?

3-4 days Signup and view all the answers

What is the role of mast cells and neutrophils in the peritoneal cavity during postoperative ileus?

They eliminate translocated bacteria Signup and view all the answers

What is the difference between open and laparoscopic procedures in terms of the early neurogenic phase of postoperative ileus?

Open procedures have a more extensive early neurogenic phase Signup and view all the answers

When does the late inflammatory phase of postoperative ileus begin?

3 hours after intestinal manipulation Signup and view all the answers

of how long time does the early neurogenic phase last

3 - 4 days after surgery. Signup and view all the answers

late inflammatory phase, occurs about 3 hours after intestinal manipulation and continues to spread for the next ?

24 hours Signup and view all the answers

What is the consequence of the bowel becoming necrotic in mesenteric ischemia?

Peritonitis develops Signup and view all the answers

What is the primary goal of treatment in mesenteric ischemia?

To reperfuse the occluded vessel Signup and view all the answers

What is the characteristic of the hyperactive stage of mesenteric ischemia?

severe pain and overactive peristalsis, may be Passage of loose stool with blood Signup and view all the answers

What is the common etiology of mesenteric ischemia in patients with atrial fibrillation?

Emboli Signup and view all the answers

What is the progression of mesenteric ischemia if left untreated?

Hyperactive stage, followed by paralytic stage, then leakage of fluid, and finally, end-organ damage Signup and view all the answers

What is the mortality rate of mesenteric ischemia if left untreated?

100% Signup and view all the answers

What is the primary function of the jejunum in the GI system?

Digesting and absorbing nutrients Signup and view all the answers

What is the consequence of resecting more than 100 cm of the ileum?

Severe malabsorption and diarrhea Signup and view all the answers

What is the minimum percentage of the small intestine required to maintain its function?

1/3 Signup and view all the answers

What is the effect of small intestinal resection on gastric motility?

Increased gastric motility Signup and view all the answers

What is the function of the ileum in the GI system?

Absorbing vitamin B12 and bile salts Signup and view all the answers

What is the effect of resecting the terminal ileum and ileocecal valve?

Accelerated intestinal content transit Signup and view all the answers

What is the primary function of the colon in the gastrointestinal system?

To absorb water Signup and view all the answers

What is the effect of resecting the small intestine on the gastrointestinal system?

The effect is significant, as the small intestine is responsible for absorbing vital nutrients and vitamins Signup and view all the answers

What is the difference between the effects of colon resection and small intestine resection on the gastrointestinal system?

Small intestine resection has a more significant impact, while colon resection has a minimal impact Signup and view all the answers

What is the consequence of full colonic resection ?

compatible with life Signup and view all the answers

What is the consequence of complete transection on the wave of activity in the intestine?

It interrupts the wave of activity Signup and view all the answers

What happens to the intestine distal to the transection after bowel anastomosis?

It relies on its own intrinsic slow-wave transmission Signup and view all the answers

What is the effect of bowel anastomoses on intestinal homeostasis and digestion?

It has no effect on intestinal homeostasis and digestion Signup and view all the answers

What is the long-term effect on MMC activity after bowel anastomosis?

It is ultimately achieved with time Signup and view all the answers

What is the effect of close approximation of the muscle layers on the intestine distal to the transection?

It attenuates the intrinsic slow-wave transmission Signup and view all the answers

Study Notes

• Preoperative anxiety leads to sympathetic stimulation, increasing norepinephrine levels, which inhibits GI tract activity, and benzodiazepines like midazolam are often used to enhance GABA's effect on GABA-A receptors, reducing anxiety.

• Midazolam's effect on small bowel motility includes increasing the duration of phase III of the migrating motor complex (MMC) in the proximal and distal parts of the duodenum, shortening the MMC by 27%.

• Volatile anesthetics affect bowel function by depressing spontaneous electrical, contractile, and propulsive activity in the stomach, small intestine, and colon, with the small intestine recovering first, followed by the stomach and then the colon.

• Rapid increases in desflurane concentration induce greater sympathetic activation, leading to increased BP and HR, but this effect is short-lived and unlikely to have a lasting impact on bowel function.

• Desflurane and isoflurane affect intestinal tissue oxygenation in a dose-dependent manner, which may influence bowel function postoperatively.

• Total intravenous anesthesia (TIVA) with propofol-remifentanil increases intestinal motility compared to sevoflurane-remifentanil, but may cause surgeon dissatisfaction.

• Nitrous oxide causes bowel distention due to its high solubility in blood, leading to gas accumulation in the bowels, and its use should be avoided in lengthy abdominal surgeries or when the bowel is already distended.

• Neuromuscular blocking drugs like succinylcholine do not affect GI motility, but can increase intragastric pressure, leading to reflux and aspiration.

• Reversal of paralysis with neostigmine increases parasympathetic activity and bowel peristalsis, but may be concerning in cases of fresh bowel anastomoses, and sugammadex may be a better alternative.

• Opioids exert their function on both central and peripheral receptors, with peripheral effects including reduced GI motility, constipation, and spasm.

• Activation of peripheral mu-receptors inhibits excitatory pathways, depresses peristaltic contraction, and increases resting muscle tone, leading to delayed gastric emptying and slow transit through the intestine.

• Combining opioids with enteral opioid receptor antagonists like methylnaltrexone or alvimopan may help alleviate opioid-induced constipation.

• The surgical procedure itself affects GI physiology and function, predisposing to postoperative ileus, which is defined as a transient cessation of coordinated bowel motility after surgical intervention.

• Manipulation of the intestines during surgery is the main factor that initiates postoperative ileus, with additional contributors including immobility, electrolyte imbalance, and intestinal wall swelling.

• Postoperative ileus has two phases: an early neurogenic phase lasting about 3-4 hours after surgery, and a late inflammatory phase.

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Description

Learn about the physiological effects of anxiety on the GI tract and how premedication with benzodiazepines can enhance the effect of neurotransmitters like GABA. Understand the importance of a good bedside manner and behavioral approaches in preoperative care.