Anesthesia Student Survival Guide.pdf - Index of

PhysiOlOGy And AnesthesiA FOr OBstetriCs ● 319
rapidly attained and regional anesthesia is contraindicated in the setting of
hemorrhagic shock. Ketamine causes less hemodynamic depression compared
with propofol or thiopental, and is a more useful intravenous induction agent
in this setting. Large bore intravenous access, blood products, and fluid warming
devices are obvious, life-saving necessities.
Post-Partum Hemorrhage
The most common causes of significant post-partum hemorrhage include
uterine atony and retained placenta. Uterine massage and intravenous
oxytocin help to prevent uterine atony post-partum. Manual uterine exploration
is usually indicated in the setting of a retained placenta. General anesthesia
or regional anesthesia may be appropriate, depending on the scenario. If
hemorrhagic shock is present, general anesthesia is usually the safest option.
Intravenous nitroglycerin and volatile anesthetics facilitate manual uterine
exploration via muscular relaxation. Vaginal and cervical lacerations can occur
during delivery and may rarely cause overt hemorrhage requiring operative
intervention.
Anesthesia for Non-Obstetric Surgery
It is desirable to avoid non-obstetric surgery during pregnancy. Depending on
the specific operation, surgical procedures can lead to miscarriage or preterm
labor. A medication is generally considered “safe” during pregnancy when
adequate, well-controlled studies fail to demonstrate a risk to the fetus. For
obvious reasons, this level of evidence is not available for most medications.
Though many agents are believed to be safe, most anesthetics have not
been studied to this degree in humans, and safety has only been demonstrated
in animal models. As such, it is prudent to avoid unnecessary fetal exposure,
especially during the period of organogenesis (1st trimester). Operations
should be delayed until the second-trimester whenever feasible. Prior to the
administration of any medication, one should weigh the benefit against the
potential for fetal harm.
If surgery must be performed, regional anesthesia should be used when
possible. It was originally thought that benzodiazepines and nitrous oxide
might cause fetal anomalies. However, there is no human data that shows a
single exposure to either drug to be unsafe. Yet many providers still choose to
avoid benzodiazepines and nitrous oxide during pregnancy.