Synaptic Transmission and Opioids in Pain Perception

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What is the maximum dose of sufentanil that should not be exceeded for labor analgesia?

10 µg

What is the recommended maximum dose of intrathecal fentanyl for labor analgesia?

25 µg

What factor has been implicated in respiratory arrest associated with intrathecal sufentanil administration in laboring women?

Previous parenteral administration of opioid

Up to what dose of epidural fentanyl has been used without evidence of respiratory depression?

100 µg Signup and view all the answers

What is the most serious side effect of neuraxial opioid administration?

Respiratory depression Signup and view all the answers

What did Jaffee et al. report in relation to intravenous fentanyl and intrathecal sufentanil administration?

Case of apnea and unresponsiveness Signup and view all the answers

Why is the greater renal clearance noted in neonates?

Decreased protein binding increases the proportion of drug available for excretion. Signup and view all the answers

How does the seizure threshold for local anesthetics in the neonate compare to that in the adult?

The seizure threshold for local anesthetics in the neonate appears to be similar to that in the adult. Signup and view all the answers

Why is the elimination half-life of local anesthetics in the fetus similar to that in the adult?

The fetus can excrete drug across the placenta back to the mother. Signup and view all the answers

Why were greater doses required to elicit toxic manifestations in fetal and neonatal lambs compared to adults?

Placental clearance of drug back to the mother and better maintenance of blood gas tensions during convulsions. Signup and view all the answers

How does the total plasma drug concentration in the mother relate to the fetus with bupivacaine?

This transfer may occur even if the total plasma drug concentration in the mother exceeds that in the fetus. Signup and view all the answers

Why is the neonate more sensitive than the adult to the depressant effects of drugs in general?

In general, the neonate is more sensitive due to the depressant effects of drugs. Signup and view all the answers

What was the effect of bupivacaine on blood flow to vital organs in asphyxiated preterm fetal lambs?

Bupivacaine reduced blood flow to vital organs. Signup and view all the answers

How did lidocaine affect mature fetal lambs exposed to asphyxia?

Lidocaine adversely affected asphyxiated preterm fetal lambs. Signup and view all the answers

Why might bupivacaine be preferable to lidocaine in the presence of fetal acidosis?

Greater maternal protein binding of bupivacaine may limit its placental transfer. Signup and view all the answers

What was a potential drawback of the in vitro study using perfused human placentas conducted by Johnson et al.?

The methodology did not consider the potential for greater fetal tissue uptake of bupivacaine. Signup and view all the answers

What is the initial step in pain perception involving stimulation of sensory nerves in the periphery?

Stimulation of sensory nerves in the periphery Signup and view all the answers

What did Yaksh demonstrate in early studies regarding morphine administration to the superficial layers of the dorsal horn?

Selective suppression of nociceptive processing without affecting motor function, sympathetic tone, or proprioception Signup and view all the answers

What happens when small doses of opioids are administered to the cortex?

Effects on nociceptive processing are negligible Signup and view all the answers

How did preterm fetal lambs exposed to lidocaine during asphyxia differ from mature fetal lambs?

Preterm fetal lambs experienced a further deterioration in response to lidocaine. Signup and view all the answers

What is the main effect of intraspinal administration of an opioid?

Exploits the pharmacology of pain-modulating and pain-relieving systems within the spinal cord Signup and view all the answers

What adaptations important for fetal survival during asphyxia result in increased blood flow and oxygen delivery to vital organs?

Circulatory adaptations. Signup and view all the answers

Which type of opioids have greater spinal bioavailability, hydrophilic or hydrophobic?

Hydrophilic Signup and view all the answers

In the study by Pedersen H, Santos AC, Morishima HO, et al., does gestational age affect the pharmacokinetics and pharmacodynamics of lidocaine?

Yes Signup and view all the answers

What is the advantage of selectively administering small doses of opioids to the spinal cord?

Profound analgesia with minimal side effects Signup and view all the answers

What are the most common side effects of neuraxial opioid administration?

Pruritus and nausea and vomiting Signup and view all the answers

What is the difference between selective administration to a receptor site like the spinal cord and systemic administration of opioids?

Selective administration at receptor site produces profound analgesia; systemic administration activates multiple receptors with unwanted side effects Signup and view all the answers

What are the most serious complications related to fetal bradycardia and maternal respiratory depression?

Fetal bradycardia and maternal respiratory depression Signup and view all the answers

What is measured throughout pregnancy in the study by Fragneto RY, Bader AM, Rosinia F, et al.?

Protein binding of lidocaine Signup and view all the answers

What is the main focus of the study by Kuhnert BR, Knapp DR, Kuhnert PM, Prochaska AL?

Maternal, fetal, and neonatal metabolism of lidocaine Signup and view all the answers