Cesarean Section Flashcards
What does anesthesia for patients undergoing cesarean section focus on?
1) Providing adequate analgesia for the mother with the least amount of cardiovascular depression
2) delivering viable neonates while minimizing negative effects of the drug
What physiological changes are seen in the mother that we have to take note of when choosing anesthetic drugs?
- Increase in blood vol. to meet increase metabolic demands
- Relative anemia from larger increase in plasma volume compared to red cell mass
- Increased heart rate and stroke volume to meet oxygen demands
- More susceptible to hypotension due to blunted response as a result of decreased baroreceptor activity
- Displacement of diaphragm due to pregnant uterus decreases tidal volume and functional residual capacity (FRC)
- More prone to hypoxemia
What drugs are considered safe in a patient having a C-section?
- Opioids - reversible if newborns require it
- Benzodiazepines - do not cause significant cardiovascular depression
- Premedication with an anticholinergic - to counter related bradycardia or vagal stimulation
What anesthetic drug would you not use in a C-section patient?
Alpha-2 agonist
- reduces cardiac output affecting placenta perfusion
- has been observed to reduce survivability of newborns
Why is rapid induction and intubation favored in a c-section patient?
- Pregnancy increases gastric acid secretion and prolonged gastric emptying
- Higher chance of regurgitation and subsequent aspiration due to increased intragastric pressure from uterus and decreased lower oesophagus sphincter tone
Why is propofol often used in C-sections?
- Rapid onset, short duration of action, minimal hepatic metabolism, rapid elimination, very little residual effect on neonates
- Must be titrated carefully to avoid significant respiratory depression and hypoxemia
Etomidate
Good option for cardiovascular function, but should be given with benzodiazepine which may cause prolonged depression in the neonate
Ketamine
- given as a combination with benzo or opioids
- prolonged depression in neonates
- reversible by flumazenil
- doens’t affect neonatal survival
Inhalants
- pregnancy lowers MAC by 25-40% = increases sensitive to inhalant
- increased respiratory drive due to increased sensitivity to PaCO2 = higher minute volume
- therefore requires less inhalant
What ventilator settings are recommended?
PEEP and IPPV
-reduction in lung expansion results in a larger degree of actelectasis
Why should you prevent hypocapnia to occur from hyperventilation?
Alkalosis reduces fetal oxygen delivery by reducing oxygen offloading (left shift in oxygen-hemoglobin dissociation curve) and reduces uterine blood flow