C-section anaesthesia Flashcards
How does pregnancy affect respiratory function and anaesthesia?
Decreased functional residual capacity (FRC) & total lung volume (TLV): Lung volume closer to alveolar closing capacity → atelectasis risk.
Higher oxygen demand & increased alveolar ventilation (V̇A): Hypoxaemia occurs quickly if apnoea or hypoventilation happens.
Decreased FRC & increased V̇A: Faster uptake of inhalant anaesthetics → risk of overdose.
Preventative actions: Pre-oxygenation (5-6 L/min for 3-5 min); oxygen supplementation; careful anaesthetic depth monitoring.
How does pregnancy impact cardiovascular function during anaesthesia?
Increased cardiac output & blood volume: If not maintained, hypotension occurs, leading to decreased fetal blood flow.
Delayed compensatory response to blood loss: Less responsive to therapy → risk of continued hypoperfusion & anaemia.
Preventative actions: Blood pressure monitoring, IV fluid therapy, prophylactic measures for hypotension.
What are the neurological effects of pregnancy on anaesthetic requirements?
Progesterone & oestrogen have sedative effects: Anaesthetic requirements and drug clearance decrease.
Increased sensitivity to anaesthetics: Higher risk of overdose with inhalants or injectables.
Preventative actions: Vigilant anaesthetic depth monitoring to avoid overdose.
How does pregnancy affect the gastrointestinal system and risk of regurgitation?
Delayed gastric emptying: Increased likelihood of ingesta in stomach → higher aspiration risk.
Decreased oesophageal sphincter tone: More prone to regurgitation and aspiration pneumonia.
Increased gastrin levels: Lower gastric pH increases regurgitation risk.
Preventative actions: Rapid induction, airway protection, extubate when laryngeal reflexes return, omeprazole for acid suppression.
How does pregnancy cause mechanical changes that impact anaesthesia?
Enlarged abdomen → diaphragm pushed cranially: Reduced lung expansion → hypoventilation & hypotension risk.
Preventative actions: Assist ventilation, oxygen supplementation, IV fluids, careful patient positioning.
Describe the general principles of C-section anaesthesia
Use short acting drugs at the lowest possible dose - titrated in
Provide oxygen and intubate, cuff tube with head elevated
Provide analgesia
Local anaesthetics to reduce MAC and provide analgesia
Tilt dam laterally to improve blood flow to placenta and offspring - also reduces regurgitation and CVC compression
Monitor ABP, administer fluids as necessary
Why should IV fluid therapy (IVFT) be slightly higher than normal in a pregnant dam?
Blood volume is increased during pregnancy, but hypotension can still occur.
Be prepared to administer fluid boluses if blood pressure drops.
When should NSAIDs be administered to a pregnant dam undergoing surgery?
At the end of the procedure, after fluids have been given.
Ensures the kidneys are functioning properly and producing urine before NSAID administration.
Why is post-operative analgesia important for the pregnant dam?
Ensures the dam is in a fit state to nurse offspring.
Reduces post-operative pain and stress.
How can vomiting and aspiration be prevented in pregnant animals?
Maropitant (1.0 mg/kg SC): Neurokinin receptor antagonist, effective antiemetic in dogs and cats.
Should be given 30-60 minutes before surgery.
Ondansetron/dolasetron (0.5-1.0 mg/kg IV or IM): 5HT3 receptor antagonists, faster onset (5-15 min), useful in emergencies.
Why should premedication be carefully selected in pregnant dams?
All drugs crossing the blood-brain barrier also cross the placenta, affecting neonates.
Xylazine increases neonatal mortality and should be avoided.
Alpha-2 agonists cause vasoconstriction & decreased cardiac output, negatively impacting the dam and fetuses.
Acepromazine is long-acting, irreversible, and can cause hypotension, especially if dehydration or blood loss occurs.
How does pregnancy affect inhalant anaesthetic requirements?
Minimum Alveolar Concentration (MAC) of inhalants is reduced due to hormonal changes.
Correlates with serum progesterone levels.
Careful monitoring of anaesthetic depth is essential to avoid overdose
What environmental preparations should be made to care for neonates?
Warm, dry box/cage prepared; warm dam to prevent hypothermia.
What is the first step in clearing airways in neonates?
Clear away membranes and fluid from mouth and nose using suction, cotton buds, or a bulb syringe.
What is the purpose of vigorous rubbing in neonatal resuscitation?
Stimulates breathing and circulation.
Why is “swinging” a neonate not recommended?
It risks cerebral trauma and aspiration.
What methods can be used to provide assisted ventilation in neonates?
Mouth-to-mouth, intubation with IPPV, oxygen supplementation.
Why might ‘flow by’ oxygen not be very effective in neonates?
It rarely reaches 100% oxygen concentration.
What is a common cause of slow heart rate (bradycardia) in neonatal puppies and kittens?
Hypoxaemia.
What drug can be used to reverse opioid effects in neonates?
Naloxone (administered IM, PO, or IV via neonatal umbilical vein).
Why is doxapram not recommended for neonatal resuscitation?
It increases oxygen demand without improving oxygenation.
What acupressure point can be stimulated to promote respiration in neonates?
GV26 (philtrum of the nose) – insert a needle and twizzle.
What is the Apgar scoring system used for in neonates?
To assess vitality based on heart rate, respiratory effort, muscle tone, reflex response, and mucous membrane color.
