Pharmacology of Anesthetics and Opioids

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Questions and Answers

What is the role of catecholamines in the body?

Catecholamines function primarily as hormones that prepare the body for stress responses, which includes increasing heart rate and blood flow.

How does pethidine affect the central nervous system?

Pethidine causes central nervous system depression, which can lead to slowed breathing and respiratory depression.

Why should inhalational anesthetics be used with care during labor?

Inhalational anesthetics can cause complications such as lightheadedness and respiratory issues, which are critical to monitor during labor.

What is a common consequence of opioid use related to pain management?

A common consequence of opioid use is the risk of developing respiratory depression, which can be life-threatening. Signup and view all the answers

What might happen if the platelet count is too low for an epidural procedure?

If platelet count is too low (e.g., less than 75,000), there is an increased risk of bleeding during an epidural procedure. Signup and view all the answers

What characterizes the pain experienced during the first stage of labor?

The pain is mostly visceral, dull, aching, poorly localized, and associated with cervical dilation. Signup and view all the answers

List two concerns that are often debated regarding labor analgesia.

Concerns for maternal safety and potential effects on the baby. Signup and view all the answers

What is one requirement of an ideal labor analgesic?

It should provide good pain relief without causing motor block. Signup and view all the answers

Name one non-pharmacological strategy for managing labor pain.

Hydrotherapy is a non-pharmacological method for pain relief during labor. Signup and view all the answers

What type of fibers conduct the sharp pain experienced during the second stage of labor?

The pain is conducted by rapidly conducting A-delta fibers. Signup and view all the answers

How does Transcutaneous Electrical Nerve Stimulation (TENS) help during labor?

TENS works by blocking pain afferent fibers from reaching the spinal cord and promotes endorphin release. Signup and view all the answers

What is a significant disadvantage of pharmacological pain relief methods during labor?

They can potentially cause hypotension and affect fetal well-being. Signup and view all the answers

What emotional approach is encouraged during labor to aid pain management?

Psycho-prophylaxis involving the birth partner is recommended. Signup and view all the answers

What is the primary mechanism by which acupuncture alleviates pain during labor?

Acupuncture alleviates pain by correcting energy imbalances in the body, leading to the release of endorphins. Signup and view all the answers

How does heat application contribute to pain management in labor?

Heat application increases blood flow, raises pain thresholds, and promotes muscle relaxation. Signup and view all the answers

What is the effect of cold application on pain perception?

Cold application slows the transmission of pain and provides increased comfort. Signup and view all the answers

What are the common side effects associated with narcotic analgesics during labor?

Common side effects include nausea, vomiting, pruritus, and drowsiness. Signup and view all the answers

Why is pethidine often preferred as an analgesic during labor?

Pethidine is preferred because it has sedative and antispasmodic properties that help relieve pain and relax the cervix. Signup and view all the answers

What is a significant disadvantage of using narcotic analgesics during labor?

A significant disadvantage is the potential for short-term respiratory depression in the baby. Signup and view all the answers

How does the use of anticoagulants impact the administration of epidural anesthesia?

Anticoagulants increase the risk of bleeding, which can complicate or contraindicate epidural anesthesia. Signup and view all the answers

What is the advantage of using patient-controlled analgesia for narcotic administration?

Patient-controlled analgesia allows women to manage their pain relief actively and customize their analgesic intake. Signup and view all the answers

What is a rare but serious complication that can result from accidental total spinal anaesthesia?

Severe hypotension, respiratory failure, unconsciousness, and death. Signup and view all the answers

What symptom could result from an overfull bladder after the effects of spinal or epidural analgesia wear off?

Bladder dysfunction. Signup and view all the answers

How can accidental drug toxicity occur during regional analgesia procedures?

It can occur with the accidental placement of a catheter within a blood vessel. Signup and view all the answers

What is a common side effect of modern epidural solutions that contain opioids?

Short-term respiratory depression of the baby. Signup and view all the answers

Where is the epidural catheter typically inserted?

The epidural catheter is typically inserted at the L2–L3, L3–L4, or L4–L5 interspace. Signup and view all the answers

What type of anaesthesia is generally not used for routine analgesia during labor?

Spinals. Signup and view all the answers

What is the purpose of aspirating the catheter during placement?

Aspirating the catheter checks for correct positioning by confirming that no blood or cerebrospinal fluid is obtained. Signup and view all the answers

What positions should a mother be maintained in after receiving a loading dose?

The mother should be kept in the right or left lateral position. Signup and view all the answers

What are common drugs used in an epidural solution?

The epidural solution typically includes low-concentration bupivacaine and an opioid like fentanyl. Signup and view all the answers

What can hypotension during epidural anesthesia lead to?

Hypotension can lead to fetal bradycardia due to reduced placental perfusion. Signup and view all the answers

How does spinal anesthesia compare to epidural anesthesia in terms of effectiveness and onset?

Spinal anesthesia is considered more effective and has a faster onset than epidural anesthesia. Signup and view all the answers

What factors can affect pain and analgesic requirements during labor?

Pain and analgesic requirements can vary based on parity, stage of labor, presence of ruptured membranes, and oxytocin augmentation. Signup and view all the answers

What is the significance of combining an opioid with a local anesthetic for epidurals?

Combining an opioid with a local anesthetic reduces the total local anesthetic required and minimizes peripheral autonomic effects. Signup and view all the answers

What is a key advantage of using nitrous oxide for analgesia during labor?

It has a quick onset and short duration of effect. Signup and view all the answers

List two disadvantages of inhalational analgesia.

It may cause light-headedness and nausea, and can result in hyperventilation. Signup and view all the answers

In what scenarios is epidural analgesia particularly indicated?

Prolonged labor and maternal hypertensive disorders. Signup and view all the answers

What are two absolute contraindications for administering epidural analgesia?

Patient refusal and increased intracranial pressure due to a mass lesion. Signup and view all the answers

Explain why adequate training and resources are important for epidural procedures.

Inadequate training can lead to improper technique and complications, while insufficient resources can hinder monitoring and resuscitation. Signup and view all the answers

What is the commonly used intravenous fluid for bolus administration during epidural analgesia?

Lactated Ringer’s solution without dextrose. Signup and view all the answers

Discuss the significance of patient positioning during the initiation of epidural analgesia.

Flexion at the upper spine and hips helps open up the lumbar vertebral spaces, improving neuroblockade. Signup and view all the answers

What is a potential risk associated with the prolonged use of inhalational analgesia in early labor?

Hypocapnoea and possible fetal hypoxia. Signup and view all the answers

Study Notes

Labour Analgesia

Labour analgesia is a topic of ongoing debate
Pain definition: An unpleasant sensory and emotional experience associated with, or resembling that associated with, actual or potential tissue damage.
Stages of Labour
- First Stage: Cervical dilation (0-3 cm Latent, 4-7 cm Active, 8-10 cm Transitional)
- Second Stage: Expulsion of the fetus
  - Begins after complete cervical dilation
  - Ends with delivery of the fetus
- Third Stage: Placental separation and delivery
- Fourth Stage: Maternal homeostatic stabilisation
Physiology of Pain in Labour
- First stage: Primarily visceral pain – dilation of cervix, distension of lower uterine segment. Slow conducting, visceral C fibers enter spinal cord at T10 to L1
- Second stage: Somatic pain – distension of pelvic floor, vagina, and perineum. Sharp, severe and well localised. Rapidly conducting A-delta fibers enter spinal cord at S2 to S4
Pain Intensity
- Visual scales can depict mild, moderate, and severe pain intensities based on the stages of labor.
Medical Effects of Labour Pain
- Pain compromises placental blood flow
- Leading to fetal hypoxia and acidosis
- Release adrenocortical hormones affecting electrolytes, carbohydrates, and protein metabolism.
- Increased catecholamine secretion leading to raised blood pressure adversely affecting fetal circulation.
- Increased risk of traumatic labour leading to potential post-traumatic stress
Need for Analgesia during Labour
- Significant controversy regarding the need for analgesia during labor.
Analgesia for Labor and Delivery
- Factors for consideration include:
- Mother's safety
- Baby's safety
- Effects on labor
- Birth is a natural process
Ideal Labor Analgesic
- Good pain relief without causing hypotension
- No adverse effects on the mother or neonate
- No motor block,
- No effect on labor or delivery (increase in C/S rate, forceps/vacuum delivery)
Classification of Analgesia
- Non-pharmacological strategies
- Pharmacological strategies
Non-Pharmacological Strategies
- Psycho prophylaxis (birth partner/mother)
- Relaxation and breathing exercises
- TENS (transcutaneous electrical nerve stimulation)
- Acupuncture
- Relaxation in warm water
- Hypnosis
- Intradermal water injection
Non-pharmacological strategies.
- Hydrotherapy
- Aromatherapy
Pharmacological Strategies
- Narcotic analgesic (opioid analgesic)
  - Mechanism: Decreases sensation of pain
  - Example: pethidine(meperidine), fentanyl, remifentanil, morphine, and tramadol
  - Side effects: CNS depression, respiratory depression, nausea, vomiting, pruritus, drowsiness.
  - Additional effects: sedative and antispasmodic, euphoria and well-being
  - Antagonists: naloxone (Narcan)
- Inhalational analgesia
  - Mechanism: Nitrous oxide (in the form of Entonox)
  - Advantage: Quick onset, short duration, more effective than pethidine
  - Disadvantage: Lightheadedness, nausea, hyperventilation, hypocapnea, dizziness and fetal hypoxia.
Regional Anesthesia/Analgesia
- Epidural analgesia
- Spinal analgesia
- Combined Spinal Epidural (CSE) analgesia
- Paracervical block
- Lumbar sympathetic block
- Pudendal block
- Perineal infiltration
Epidural Analgesia
- Main indication: Effective pain relief
- Other considerations: Prolonged labor, maternal hypertensive disorders, and multiple gestations, high risk of operative intervention
- Contraindications: Patient refusal/inability to cooperate, increased intracranial pressure, skin/soft tissue infection, frank coagulopathy, recent anticoagulation, uncorrected maternal hypovolemia, inadequate training/experience, inadequate resources.
Technique and Positioning
- Skin cleansing and local infiltration,
- Proper positioning for insertion
- Positioning after epidural insertion
- Test dose administration to confirm catheter position
Follow Up Post-Epidural Administration
- Monitoring Blood Pressure
- Prevention/Management of Hypotension
- Reducing Maternal/Cardiac Output
Choice of Drugs
- Epidural solution: Mixture of low concentration local anaesthetic (e.g., bupivacaine) and opioid (e.g., fentanyl)
- Effects of combining local anesthetics and opioids: Reduced need for local anaesthetic, reduced motor blockade and peripheral autonomic effects (e.g., hypotension).
- Factors affecting Analgesic Requirements: Parity, stage of labour, ruptured membranes, oxytocin augmentation

-Spinal Anaesthesia - More effective than epidural, quicker onset. - Injection into the subarachnoid space

Complications of Regional Analgesia
- Accidental dural puncture
- Accidental total spinal anesthesia
- Spinal hematomas/neurological complications
- Drug toxicity
- Bladder dysfunction
- Backache
- Hypotension
- Short-term respiratory depression in the baby
Side Effects of Neuraxial Analgesia
- Hypotension
- Pruritis
- Nausea and vomiting
- Fever
- Shivering
- Urinary retention
- Recrudescence of HSV
- Delayed gastric emptying
Conclusion
- Delivery of an infant into the arms of a conscious and pain-free mother is a rewarding moment in medicine.

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Description

This quiz explores the role of catecholamines in the body and the implications of using pethidine and inhalational anesthetics during labor. It also investigates the consequences of opioid use in pain management and the risks associated with low platelet counts during epidural procedures.