Opioids Organ Systems Effects (book)

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Questions and Answers

How does morphine impact the sympathetic nervous system's tone to peripheral veins?

Decreases it (correct)

Has no effect

Increases it

Activates it

Which of the following is a potential cause of orthostatic hypotension in patients receiving morphine?

Enhanced baroreceptor reflexes

Decreased venous pooling

Increased cardiac output

Impaired compensatory sympathetic responses (correct)

How does morphine induce bradycardia in patients?

By activating the sinoatrial node

By stimulating sympathetic nerves

By releasing histamine

By increasing vagal nerve activity (correct)

What effect does morphine have on the conduction of cardiac impulses through the atrioventricular node?

Slows conduction Signup and view all the answers

Why does morphine potentially decrease vulnerability to ventricular fibrillation?

Due to bradycardia effects Signup and view all the answers

What effect does the administration of opioids before anesthesia have on heart rate?

Decrease heart rate Signup and view all the answers

How can the decrease in systemic blood pressure due to morphine-induced histamine release be minimized?

Limiting the rate of morphine infusion intravenously Signup and view all the answers

Which opioid, when administered intravenously, does not produce substantial increases in histamine concentration?

Fentanyl Signup and view all the answers

What is a characteristic of opioid-induced depression of ventilation?

Prolonged pauses between breaths Signup and view all the answers

What is the likely result of high doses of opioids on ventilation?

Apnea Signup and view all the answers

How might physostigmine impact the depression of ventilation caused by opioids?

Antagonize depression of ventilation Signup and view all the answers

Which of the following is a significant risk associated with opioid overdose?

Depression of ventilation Signup and view all the answers

Which of the following cardiovascular effects is NOT seen when an opioid agonist is administered alone?

Increased systemic vascular resistance Signup and view all the answers

What is the mechanism through which opioids protect the myocardium from ischemia?

Stimulation of mitochondrial ATP production Signup and view all the answers

Which neurotransmitter is involved in the explanation for opioid-induced increased skeletal muscle tone?

GABA Signup and view all the answers

What would likely cause interference with manual ventilation after rapid IV administration of large doses of fentanyl?

Laryngeal musculature contraction Signup and view all the answers

How can the difficult ventilation induced by sufentanil be treated?

Muscle relaxation with neuromuscular blocking drugs Signup and view all the answers

What effect does morphine titration frequently induce before the onset of analgesia?

Sedation Signup and view all the answers

What percent of patients experience sedation during morphine titration?

60% Signup and view all the answers

What is the main effect of opioids on the hypothalamic-pituitary-gonadal axis?

Increased prolactin concentration Signup and view all the answers

What is the common manifestation of opioid overdose related to ventilation?

Apnea Signup and view all the answers

What can opioid overdose cause in terms of pupil size when severe arterial hypoxemia is present?

Mydriasis Signup and view all the answers

Which treatment is recommended for opioid overdose to reverse its effects?

Mechanical ventilation with oxygen Signup and view all the answers

What may be a potential consequence of administering an opioid antagonist like naloxone to treat opioid overdose?

Precipitation of acute withdrawal symptoms Signup and view all the answers

What phenomenon may be paradoxically associated with the preinduction administration of certain opioids like fentanyl?

Significant reflex coughing Signup and view all the answers

Which opioid increases common bile duct pressure the most?

Fentanyl Signup and view all the answers

What can mislead the interpretation of a cholangiogram during surgery?

Sphincter of Oddi spasm caused by opioids Signup and view all the answers

Which substance can reverse opioid-induced biliary smooth muscle spasm without antagonizing the analgesic effects of opioids?

Glucagon Signup and view all the answers

What is a potential consequence of opioid-induced biliary smooth muscle spasm during surgery?

Misinterpretation of cholangiogram Signup and view all the answers

Which factor increases the ventilatory depressant effects of opioids according to the text?

Advanced age Signup and view all the answers

What effect do opioids have on ciliary activity in the airways?

Depression of activity Signup and view all the answers

Which opioid is known for its significant cough suppression effects?

Codeine Signup and view all the answers

'One useful property of dextrorotatory isomers (such as dextromethorphan) is that they can suppress cough but do not produce what?'

Analgesia or depression of ventilation Signup and view all the answers

How can the opioid-induced effects on the ureter be reversed?

Anticholinergic drug such as atropine Signup and view all the answers

What is responsible for urinary urgency produced by opioids?

Augmentation of detrusor muscle tone Signup and view all the answers

What cutaneous changes are commonly seen with morphine administration?

Dilation of blood vessels and flushing of face Signup and view all the answers

What is released by morphine that contributes to skin changes?

Histamine Signup and view all the answers

How are opioids transported across the placenta?

Readily Signup and view all the answers

Which drug interaction may lead to exaggerated ventilatory depressant effects of opioids?

Amphetamines Signup and view all the answers

What effect do commonly used opioids have on gastrointestinal smooth muscles?

Spasm causing constipation Signup and view all the answers

Why does constipation often accompany therapy with opioids?

Increased passage of intestinal contents through the colon Signup and view all the answers

Why does increased biliary pressure occur with opioids?

Gallbladder contraction against a closed or narrowed Oddi sphincter Signup and view all the answers

What is the mechanism behind opioid-induced nausea and vomiting?

Direct stimulation of the chemoreceptor trigger zone Signup and view all the answers

How does peripheral-acting opioid antagonists help counter the effects of preoperative opioids?

By reversing the effects on gastric emptying and absorption Signup and view all the answers

What contributes to opioid-induced nausea and vomiting?

Activation of dopamine receptors in the chemoreceptor trigger zone Signup and view all the answers

Why does IV administration of morphine produce less nausea and vomiting compared to IM administration?

IV administration reaches the vomiting center more rapidly Signup and view all the answers

What contributes to the development of physical dependence on morphine?

Psychological need for opioids with repeated use Signup and view all the answers

How is physical dependence on morphine affected by emotional stability?

Emotional instability accelerates physical dependence development Signup and view all the answers

What symptoms are associated with the initial phase of opioid withdrawal?

Yawning, lacrimation, and diaphoresis Signup and view all the answers

What characterizes opioid withdrawal symptoms after discontinuation?

Initial peak in symptoms followed by rapid decline Signup and view all the answers

What is one way that pharmacodynamic tolerance to opioids develops?

Upregulation of cAMP system Signup and view all the answers

Study Notes

Opioids and their Effects

Cardiovascular System

Morphine does not cause direct myocardial depression or hypotension in supine and normovolemic patients
However, it can cause orthostatic hypotension and syncope when patients change from a supine to a standing position
Morphine decreases sympathetic nervous system tone to peripheral veins, resulting in venous pooling and subsequent decreases in venous return, cardiac output, and blood pressure
It can also cause decreases in systemic blood pressure due to bradycardia or histamine release

Respiratory System

Opioids produce dose-dependent depression of ventilation
Depression of ventilation is characterized by decreased responsiveness of ventilation centers to carbon dioxide
Opioids also interfere with pontine and medullary ventilatory centers, leading to prolonged pauses between breaths and periodic breathing
High doses of opioids may result in apnea, but the patient remains conscious and able to initiate a breath if asked to do so

Neurological System

Opioids depress cough by effects on the medullary cough centers, which are distinct from the effects of opioids on ventilation
Dose-dependent depression of ciliary activity in the airways
Opioids decrease cerebral blood flow and possibly intracranial pressure (ICP) in the absence of hypoventilation
Morphine-induced sedation occurs in up to 60% of patients during morphine titration

Genitourinary System

Morphine increases the tone and peristaltic activity of the ureter
Opioids produce urinary urgency due to opioid-induced augmentation of detrusor muscle tone
Antidiuresis occurs in animals, but not in humans, in the absence of painful surgical stimulation

Cutaneous Changes

Morphine causes cutaneous blood vessels to dilate, resulting in flushing of the face, neck, and upper chest
Histamine release accounts for urticaria and erythema commonly seen at the morphine injection site

Placental Transfer

Opioids are readily transported across the placenta, which can result in depression of the neonate
Maternal administration of morphine may produce greater neonatal depression than meperidine

Drug Interactions

Ventilatory depressant effects of opioids may be exaggerated by amphetamines, phenothiazines, monoamine oxidase inhibitors, and tricyclic antidepressants
Sympathomimetic drugs enhance analgesia produced by opioids### Opioid Effects
Preoperative medication with an opioid can slow gastric emptying, increasing the risk of aspiration, and delay the absorption of orally administered drugs.
Opioid-induced nausea and vomiting are caused by direct stimulation of the chemoreceptor trigger zone in the floor of the fourth ventricle.
Morphine can cause nausea and vomiting by increasing gastrointestinal secretions and delaying passage of intestinal contents toward the colon.
IV administration of morphine produces less nausea and vomiting than intramuscular (IM) administration, due to the opioid reaching the vomiting center as rapidly as it reaches the chemoreceptor trigger zone.
Nausea and vomiting are relatively uncommon in recumbent patients given morphine, suggesting a vestibular component may contribute to opioid-induced nausea and vomiting.

Physical Dependence and Tolerance

Tolerance develops to analgesic, euphoric, sedative, depression of ventilation, and emetic effects of opioids, but not to their effects on miosis and bowel motility.
Physical dependence depends on the agonist effect of opioids and does not occur with opioid antagonists or opioid agonist-antagonists.
Physical dependence on morphine typically requires about 25 days to develop, but may occur sooner in emotionally unstable persons.
Discontinuation of the opioid agonist produces a typical withdrawal abstinence syndrome, including yawning, diaphoresis, lacrimation, and insomnia.

Withdrawal Symptoms

Initial symptoms of withdrawal include yawning, diaphoresis, lacrimation, and coryza.
Insomnia and restlessness are prominent, followed by abdominal cramps, nausea, vomiting, and diarrhea.
Withdrawal symptoms reach their peak in 72 hours and then decline over the next 7 to 10 days.
Tolerance to morphine is rapidly lost during withdrawal, and the syndrome can be terminated by a modest dose of opioid agonist.

Hormonal Changes

Prolonged opioid therapy may influence the hypothalamic-pituitary-adrenal axis and the hypothalamic-pituitary-gonadal axis, leading to endocrine and immune effects.
Morphine may cause a progressive decrease in plasma cortisol concentrations.
Opioids may modulate hormone release, including increased prolactin and decreased luteinizing hormone, follicle-stimulating hormone, testosterone, and estrogen concentrations.

Overdose

The principal manifestation of opioid overdose is depression of ventilation, manifesting as a slow breathing frequency, which may progress to apnea.
Pupils are symmetric and miotic unless severe arterial hypoxemia is present, which results in mydriasis.
Treatment of opioid overdose involves mechanical ventilation with oxygen and administration of an opioid antagonist, such as naloxone.

Provocation of Coughing

Preinduction administration of fentanyl, sufentanil, or alfentanil may be associated with significant reflex coughing.
The exact cause of opioid-induced cough is unclear, but is thought to be due to an imbalance between sympathetic and vagal innervation of the airways and/or stimulation of juxtacapillary irritant receptors.

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