Obstetric Anesthesia Video:

In this video, Dr. Cristian Arzola answers questions related to providing anesthesia services in obstetrics.

Transcript of the video:

Dr. Arzola: My name is Dr. Cristian Arzola, an associate professor at the Department of Anesthesia at Mount Sinai Hospital at the University of Toronto. I specialize in Obstetric Anesthesia and I’m here today to answer questions related to this topic.

Question 1: What are some of the major physiologic changes that occur during pregnancy that are particularly relevant to the practice of Anesthesia?

Dr. Arzola: During pregnancy, women are subjected to great physiological changes and the major systems involved are the cardiac and the respiratory system. First, we have to mention that there is an increase in cardiac demand due to the growing fetus. Second, we have to mention that because of the gravid uterus in the abdomen we have to consider not just mechanical but also physiological changes such as the risk of aortocaval compression. From the respiratory point of view, there is a decrease in functional residual capacity and because of that there is an increase in oxygen consumption which results in rapid oxygen desaturation.

Question 2: How does management of the obstetrical population differ from providing anesthesia to non-pregnant patients?

Dr. Arzola: First, we have to consider that we take care of the well-being of two patients, mother and fetus. Effective anesthetic management is particularly important because pregnant women have changes in pharmacokinetics and pharmacodynamics. For example, there is a decrease in the requirement of volatile agents, at the same time there is an increase in requirement of intravenous anesthetic that will definitely dictate our management.

Question 3: Can you describe the basic approach to pain relief in labour based on pain pathways and the characteristics of labour pain?

Dr. Arzola: During the first stage of labour, pain is generated by the contraction of the lower segment and dilation of the cervix which is transmitted through T10-L1 nerve roots. But during the second stage pain is generated also from the vagina and perineum which is further transmitted through the S2-S4 nerve roots. In this way knowledge of pain pathways allows for numerous strategies to alleviate pain.

Question 4: What are the modes of analgesia available for a woman during labour and which are the most commonly used?

Dr. Arzola: There are multiple strategies: non-pharmacologic and pharmacologic. For example, within the non-pharmacologic techniques we can mention breathing techniques, relaxation, and hypnosis. Pharmacologic strategies include systemic analgesia with opioids, also inhalation analgesia with nitrous oxide. We can do infiltration of local anesthetic in the perineum and nerve blocks such as paracervical and pudendal blocks. But lastly, the most commonly used are neuraxial blocks with epidurals and combined spinal epidural techniques.

Question 5: Can you outline the major differences between a spinal vs epidural anesthetic?

Dr. Arzola: First, spinal anesthetics are usually used for a cesarean delivery whereas an epidural can be used for analgesia, preserving motor strength during vaginal delivery, as well as anesthesia for cesarean delivery. The administration of anesthetic agents during an epidural is before the dura mater in the epidural space. In a spinal anesthetic, the anesthetic agents are delivered through the dura mater in the subarachnoid space. The dose required for spinal anesthesia is much lower and the onset of action is faster than an epidural. A spinal anesthetic is a single shot of anesthetic agents resulting in a limited duration of action, whereas an epidural anesthetic with a catheter allows for continuous duration of action.

Question 6: Can you explain some minor and major complications in neuraxial anesthesia?

Dr. Arzola: Minor complications include poor analgesia due to inadequate block, hypotension from demonstration of local anesthetics, pruritis from opioids and post dural puncture headaches. More serious and potentially life-threatening complications include high block causing respiratory/cardiovascular collapse, epidural hematoma, and abscess causing nerve injury.

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