Gastrointestinal System Changes During Pregnancy

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Questions and Answers

What is the effect of progesterone on the lower esophageal sphincter?

It has no effect on the lower esophageal sphincter.

It increases the competence of the lower esophageal sphincter.

It increases the tone of the lower esophageal sphincter.

It reduces the competence of the lower esophageal sphincter. (correct)

What is the recommended medication to stimulate gastric emptying and increase lower esophageal sphincter tone?

Sodium citrate

Metoclopramide (correct)

Ranitidine

Omeprazole

What is the purpose of positioning patients at a 45° angle before induction?

To reduce the fall in FRC (correct)

To decrease saliva production in the airway

To increase oxygen content in the FRC

To increase the fall in FRC

What is the purpose of applying cricoid pressure during anesthesia?

To prevent passive reflux Signup and view all the answers

What is the benefit of using antimuscarinic drugs before induction?

To reduce the quantity of saliva in the airway Signup and view all the answers

Why are pregnant patients considered to have 'full stomachs', regardless of fasting?

All of the above Signup and view all the answers

What is the purpose of using PEEP during mechanical ventilation?

To maintain alveolar patency and prevent hypoxia Signup and view all the answers

What is the purpose of administering a non-particulate antacid, such as sodium citrate?

To reduce gastric acidity and volume Signup and view all the answers

What is the benefit of recruitment maneuvers during intra-operative care?

To open collapsed portions of the lung Signup and view all the answers

When should positive pressure ventilation be initiated during anesthesia?

If the patient's pulse oximetry reading starts to decline or a difficult airway is encountered Signup and view all the answers

What is the effect of placental gastrin on gastric acid secretion?

It increases gastric acid secretion Signup and view all the answers

What is the benefit of continuing oxygen therapy post-operatively?

To increase oxygenation in patients at risk of hypoxia Signup and view all the answers

What is the benefit of using CPAP masks post-operatively in obese patients?

To reduce airway collapse and atelectasis Signup and view all the answers

What is the recommended patient positioning to prevent passive reflux?

A slight reverse Trendelenburg position Signup and view all the answers

What is the benefit of providing good postoperative analgesia?

To increase deep breathing and coughing Signup and view all the answers

What is the benefit of extubating ICU patients onto bi-level noninvasive ventilation?

To reduce the rate of re-intubation Signup and view all the answers

What is the effect of ketamine on bronchial smooth muscle tone?

Reduction in tone Signup and view all the answers

Which of the following is NOT a method to decrease the effect of anesthesia on the respiratory system?

Withholding oxygen in the postoperative period Signup and view all the answers

What is a negative effect of isoflurane on the respiratory system?

Increased secretions Signup and view all the answers

Which anesthetic drug does NOT cause a dose-dependent reduction in minute ventilation?

Etomidate Signup and view all the answers

How does anesthesia affect gas exchange?

Change in tidal volume Signup and view all the answers

What is the definition of an inhalational anesthetic?

A chemical compound possessing general anesthetic properties that can be delivered via inhalation Signup and view all the answers

What is NOT a method of administering an inhalational anesthetic?

Oral tablet Signup and view all the answers

What is the benefit of using positive end-expiratory pressure (PEEP) in anesthesia?

Maintains alveolar patency and prevents hypoxia Signup and view all the answers

What is the minimum alveolar concentration of an inhaled anesthetic that prevents movement in 50% of patients in response to a standardized stimulus?

The MAC of the anesthetic Signup and view all the answers

Which of the following factors does not affect the MAC of an anesthetic?

Sex Signup and view all the answers

What is the characteristic of an ideal inhalational anesthetic?

Non-flammable and non-explosive at room temperature Signup and view all the answers

What is the MAC of Sevoflurane?

2.0% Signup and view all the answers

Which of the following decreases the MAC of an anesthetic?

Hypocapnia Signup and view all the answers

What is the MAC of Nitrous oxide?

105% Signup and view all the answers

Which of the following is a characteristic of sevoflurane on the respiratory system?

Respiratory depressant with increased rate and decreased tidal volume Signup and view all the answers

What is the effect of sevoflurane on the cardiovascular system?

Vasodilatation and hypotension may occur Signup and view all the answers

What is the effect of sevoflurane on uterine relaxation?

Dose-dependent uterine relaxation, less than isoflurane and sevoflurane Signup and view all the answers

Which of the following does not affect MAC?

Hyponatraemia Signup and view all the answers

What is the MAC of sevoflurane?

2 Signup and view all the answers

Which of the following anesthetics requires the use of an electrically powered vaporizer?

Desflurane Signup and view all the answers

What is a characteristic of an ideal inhalational anesthetic?

Flammable at room temperature Signup and view all the answers

Which of the following is a side effect of sevoflurane on the skeletal muscle?

Skeletal muscle relaxation Signup and view all the answers

Study Notes

Gastrointestinal System Changes in Pregnancy

Mechanical and hormonal alterations lead to changes in the gastrointestinal system during pregnancy.
The enlarging uterus puts pressure on the stomach, causing an incompetent lower esophageal sphincter.
Progesterone reduces the competence of the lower esophageal sphincter.
Placental gastrin increases gastric acid secretion.
These changes cause reflux of gastric acid into the esophagus and delayed gastric emptying.
Pregnant patients are at risk for aspiration during anesthesia.

Anesthetic Considerations for Gastrointestinal Changes in Pregnancy

Pregnant patients should be considered to have "full stomachs" regardless of fasting.
Administer medications to reduce gastric acidity and volume before anesthesia.
Use a non-particulate antacid, such as sodium citrate, and Metoclopramide (Plasil) 10mg IV to stimulate gastric emptying and increase lower esophageal sphincter tone.
Position the patient with a roll under the right hip and a slight reverse Trendelenburg position to prevent passive reflux.
Apply cricoid pressure until the patient is intubated.
Avoid routine administration of positive pressure ventilation before intubation.

Pre-operative and Intra-operative Management

Position patients at a 45° angle before induction to reduce the fall in FRC.
Pre-oxygenate to maximize oxygen content in the FRC.
Administer antimuscarinic drugs, such as atropine or glycopyrrolate, before induction to reduce saliva in the airway.
Use mechanical ventilation, especially for obese patients, to reduce airway collapse and atelectasis.
Apply positive end-expiratory pressure (PEEP) to maintain alveolar patency and prevent hypoxia.
Use recruitment maneuvers to open collapsed portions of the lung.

Post-operative Management

Continue oxygen into the postoperative period for patients at risk of hypoxia.
Use a head-up tilt to increase FRC and prevent atelectasis.
Extubate obese patients onto a CPAP mask to prevent airway collapse and atelectasis.
Ensure good postoperative analgesia and encourage patients to take deep breaths and cough.

Inhalational Anesthetics

Definition: Inhalational anesthetics are chemical compounds that can be delivered via inhalation and possess general anesthetic properties.
Administration: Inhalational anesthetics are administered through a face mask, laryngeal mask airway, or tracheal tube connected to an anesthetic vaporizer and delivery system.
Main use: Inhalational anesthetics are used to maintain anesthesia, and some can be used for induction.

Minimum Alveolar Concentration (MAC)

Definition: MAC is the alveolar concentration of an inhaled anesthetic that prevents movement in 50% of patients in response to a standardized stimulus.
Examples: Halothane MAC 0.75%, Isoflurane MAC 1.2%, Desflurane MAC 6.0%, Sevoflurane MAC 2.0%

Factors Affecting MAC

Factors increasing MAC:
- Hyperthermia
- Hypernatraemia
- Sympatho-adrenal stimulation
- Chronic alcohol abuse
- Chronic opioid abuse
- Increases in ambient pressure
- Hypercapnia
- Decreasing age
- Thyrotoxicosis
Factors decreasing MAC:
- Nitrous oxide
- Hypothyroid/myxedema
- Hypocapnia
- Hypothermia
- Hyponatraemia
- Increasing age
- Hypoxaemia
- Hypotension
- Anemia
- Pregnancy
- CNS depressant drugs
- Other drugs: lithium, lidocaine, magnesium, acute alcohol abuse

Ideal Inhalational Anesthetic Characteristics

Non-flammable, non-explosive at room temperature
Stable in light
Does not cause airway irritation
Has minimal respiratory and cardiovascular effects
Does not cause uterine relaxation or skeletal muscle relaxation
Does not potentiate non-depolarizing neuromuscular blockade

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Description

This quiz covers the mechanical and hormonal changes that occur in the gastrointestinal system during pregnancy, including effects on the stomach and esophageal sphincter.