ABSTRACT
OBJECTIVE: To describe the effects of anaesthetic techniques and agents on the risk of fetal distress during labour pain relief and anaesthesia for caesarean section. STUDY DESIGN: Data on obstetric anaesthesia- and analgesia-induced fetal distress were searched in Medline database using MESH terms: fetal distress, anaesthesia, analgesia, labour, caesarean section, and umbilical artery pH. Trials published in English or French language were selected. RESULTS: Because of their haemodynamic effects, regional anaesthesia and analgesia, especially spinal anaesthesia for Caesarean section, could induce a decrease in umbilical artery pH (UApH). Moreover, intravenous ephedrine, especially when used in large doses can worsen the acidosis. Labour epidural analgesia is associated with a better acid-base balance than systemic analgesia. Experimental studies have demonstrated harmful effects of systemic opioids and hypnotic drugs on UApH and the foetal brain respectively. Clinical implications of these potentially detrimental effects remain to be determined. CONCLUSION: All obstetric anaesthesia and analgesia techniques are associated with a theoretical risk of fetal distress, but given the fact that regional anaesthesia techniques are also associated with well-demonstrated benefits for the mother and the newborn, the latter remain the preferred choice in obstetric practice.
Subject(s)
Analgesia, Obstetrical/adverse effects , Anesthesia, Obstetrical/adverse effects , Anesthetics, Local/adverse effects , Fetal Distress/etiology , Narcotics/adverse effects , Acidosis/chemically induced , Analgesia, Obstetrical/methods , Anesthesia, Epidural/adverse effects , Anesthesia, General/adverse effects , Anesthesia, Obstetrical/methods , Anesthesia, Spinal/adverse effects , Anesthetics, Local/pharmacokinetics , Bradycardia/chemically induced , Brain/drug effects , Brain/embryology , Cesarean Section , Ephedrine/adverse effects , Female , Fetal Diseases/chemically induced , Fetal Heart/drug effects , Humans , Hypotension/drug therapy , Infant, Newborn , Injections, Spinal/adverse effects , Narcotics/pharmacokinetics , Obstetric Labor Complications/drug therapy , Pregnancy , Prenatal Exposure Delayed Effects , Umbilical ArteriesABSTRACT
OBJECTIVE: To analyze the different preventive and curative strategies for the management of hypotension during spinal anaesthesia for caesarean section. DATA SOURCES: Data related to hypotension during spinal anesthesia for caesarean section were searched in the Medline database. Trials published in English or French were reviewed. DATA SYNTHESIS: Hypotension during caesarean section under spinal anaesthesia is very frequent (55 to 90%) if not prevented. It can induce complications for the mother and/or the fetus. Crystalloid preload alone is ineffective. Colloid preload is effective but might be better used as a second line treatment. Ephedrine has been the vasopressor of choice for long, but has a weak prophylactic efficacy. In addition, it can induce maternal cardiovascular adverse effects and fetal acidosis. Prophylactic phenylephrine, with or without ephedrine according to maternal heart rate, is at least as effective as ephedrine, with less adverse effects. Crystalloid loading at the time of spinal injection ("co-/post-loading") enhances the haemodynamic control provided by vasopressors. CONCLUSION: Hypotension during spinal anesthesia for caesarean section must be systematically detected, prevented and treated without delay. The association of vasopressor(s) (phenylephrine with or without ephedrine) with a rapid crystalloid loading at the time of spinal injection represents the most interesting strategy nowadays.