C-section anesthesia Flashcards
What are the differences in patent stability between emerg and scheduled c section
Scheduled c sections: fasted and stable patients
Emergency c sections: unstable, potentially critical patients
Dehydration, exhaustion, decreased sympathetic response, hypocalcaemia (milk fever), hypoglycemia, sepsis
Emergency C-sections are higher risk for regurgitation and aspiration pneumonia
Feline C-sections are uncommon, but when they do occur the patient is critically ill and often in a septic state
Physiological anemia in pregnant patients
PCV 30–35 %
Increased plasma volume without an increase in RBCs
What happens to the cardiac system during pregnancy
Increased Cardiac output
Increase HR
Increase stroke volume
Decreased systemic vascular resistance
What happens to the resp system during pregnancy
Decreased oxygen reserves
Decreased functional residual capacity
Increased RR, decreased tidal volume
Hyperventilation leading to hypocapnia (ETCO2 30 mmHg)
Increased oxygen consumption (20%)
What happens to the GIT system during pregnancy
Cranial displacement of stomach
Delayed gastric emptying
Increased gastric secretions
Relaxed lower esophageal sphincter tone
Anticipated Anesthetic Complications with c sections
Hypotension
Hypoxemia/Hypoxia
Hypoventilation and Hypercapnia
Regurgitation and Aspiration Pneumonia
Hypothermia
How does hypotension affect pregnant patietns and what are teh causes of hypotension
Hypotension significantly effects uterine perfusion and fetal oxygenation
Causes of hypotension:
Anesthetic drugs
Dehydration
Intraoperative fluid losses
Abdominal distension and patient positioning
How can the position of a pregnant patient cause problems
Aorto-caval compression syndrome
Pregnant patients in dorsal recumbency will have decreased venous return and decreased uterine perfusion.
More significant in species with one fetus positioned centrally in abdomen over vena cava (ex. horse)
Treatment of hypotension during c sections
Decrease amount of inhalant anesthetic
Treat with crystalloids or colloids
Don’t treat with vasoconstrictors = decreased uterine perfusion
Epinephrine, phenylephrine
Dobutamine intravenous infusion
Not likely seen in private practice
Hypoxemia/Hypoxia during a c section
Hypoxemia: decreased levels of oxygen present in the blood
Minimize hypoxemia during induction and recovery
- Quick induction and intubation required
-Pre-oxygenate for 3–5 minutes
-Monitor SPO2 and provide supplemental O2 in recovery
Hypoxia: decreased levels of oxygen delivered to the tissues
Organ perfusion is important to maintain fetal oxygenation during anesthesia
- Maintain oxygenation (SPO2> 95%)
-Maintain Blood Pressure (MAP > 60 mmHg )
What can cause a c section to hypoventialte
Patient position: sternal is best or dorsal recumbency with elevated chest
Avoid dorsal recumbency until in surgery
Hypercapnia can cause decreased uterine perfusion (Sympathetic Nervous System Stimulation)
Manual or mechanical ventilation if needed
Avoid high Peak Inspiratory Pressure (PIP) and use high RR with low tidal volume instead
How do you stop post op resp complications in c sections
Perioperative treatment: metoclopramide, omeprazole or pantoprazole, maropitant (Cerenia)
Intubate and secure the airway quickly
Anticipate regurgitation
Check oral cavity prior to extubation
Suction and flush esophagus
Minimal to no sedation on recovery
Why is hypothermia expected with c sections
Significant hypothermia should be anticipated
Reproductive organs exposed to room air during procedure
Uterus has large blood vessels that cool patient rapidly
Abdominal cavity flush?
Hypothermia will prolong recovery to nursing of neonates
Pharmacological Considerations with c sections
All anesthetic agents cross the placenta*
Minimize the use of sedatives in the premedication as this will cause sedation, respiratory depression and C/V depression in neonates post-operatively
Drugs given to dam will have a more pronounced and longer effect in the newborns
MAC reduction of 30% in pregnant animals
Should you premed a dam
No Premedication, if dam is calm and co-operative, but minimize patient stress
Opioid Mu agonist
(ex. Hydromorphone, methadone, fentanyl)
Avoid sedatives
(ex. dexmedetomidine, acepromazine)
How do you induce for a c section
Propofol and alfaxalone can be used with similar effects
Wait 10 minutes after induction before removing puppies
Avoid benzodiazepines, can cause floppy infant syndrome
Avoid ketamine
Risks associated with mask inductions using only inhalational anesthetic (stress, regurgitation, aspiration)
What intraop analgesics are used during c sections
Opioids:
if not in premedication, the dam can receive an opioid once the puppies have been delivered
Ultra short acting mu opioid CRI (ex. Remifentanil) is ideal intra-op, can be given before removal of puppies
Local blocks:
Incisional line block, splash block (bupivacaine or lidocaine)
Lumbosacral Epidural for c sections
1ml/5kg dose, but total volume of the epidural should be decreased to 50-75%
Epidurals should only be performed by efficient, trained professionals
Lidocaine is preferred due to shorter duration of action which allows the dam to be up and mobile quicker
Avoid Morphine, effects can last up to 24 hours
What are the negative side effects of an epidural during a c section
Negative side effects:
Sympathetic nerve blockade resulting in significant hypotension
Post-op loss of function in hind limbs can cause stress and the patient may require a prolonged stay in hospital
How do you do post op care of a c section
Inadequate pain control can decrease milk production
Post-operative analgesia: mu-agonist opioid and an NSAID
A single dose post-op NSAID (ex. Meloxicam) has no significant effects on the puppies
Ideally dam and puppies should be reunited and nursing ASAP
Post-op goal is to get mom and pups healthy and at home
Decreased stress
Hospital acquired infections
How do you resuscitate a neonate
Changes in neonate resuscitation techniques are on the horizon.
RECOVER guidelines will include neonate resuscitation, coming out soon.
Do not swing puppies!
There needs to be a large group of trained individuals to assist in neonate resuscitation after delivery
Alternatively, have a trained technician or veterinarian supervising
Resuscitation in order of priority: warmth, airway, breathing, circulation, and drugs (Traas2008)
10% neonate mortality rates in C-sections and up to 20% in emergency C-sections
Neonate Resuscitation Supplies
Warming device (incubator)
Warm dry towels
Bulb syringes
Multiple O2 Sources
Cat-sized O2 masks
Intubation supplies (14-18 ga IV cath, ET tube 1 and 2)
25 ga needles and 1 ml syringes
Naloxone, epinephrine, doxapram
Hemostats, suture
Multi-colored collars
Neonate Warming
Avoid Hypothermia, actively warm neonates
Resuscitate with warm towels, replace towel as they cool
Warm water bottles, Bair hugger
Environmental temperature is important (32 ⁰C incubator)
Place in incubator or warm box until puppies can be reunited with dam
Normal neonate temperature (35–37.7*C)
How do you secure a neonates airway
The primary cause of neonate mortality is hypoxia
Bradycardia is usually a response to hypoxia
Remove any debris from neonate’s face
Lower head to drain fluids from airway
Clears own airway by crying
Bulb syringe can be used to gently suction nostrils and oropharynx
how do you get a neonate to breathe
Breathing can be stimulated by gently rubbing neonate with a warm, dry towel
Supplemental O2 with face mask if neonate is breathing
Acupuncture point GV 26
RR is 10-18 Bpm in newborns
will settle into a more regular pattern over time
Acupuncture Point GV 26
Midline between upper lip and nose
Stimulates respiration, cardiovascular system and sympathetic nervous system
If initial attempts to stimulate respiration is unsuccessful:
Intubate using a 14–18- gauge IV catheter or ETT 2 mm
Gentle intubation, difficult due to anatomy
Ventilate gently, and watch chest for over inflation
Use a low PIP (10 cmH2O)
Ventilate at the RR of 30-40 Bpm
Can try ventilation with a tight-fitting mask
how do you help with neonate ciruclation
Bradycardia most often associated with hypoxia
Cardiac Compressions 100-120 Bpm
Stop resuscitation if there is no response in 15–20 minutes
What drugs can you give a neonate
IV access Via Jugular or Umbilical vein
Breathing:
-Reversing any respiratory depressing drugs
- Naloxone sublingually (0.01 mg/kg)
- Doxapram 1-2 drops sublingually
Circulation:
- Epinephrine 0.01–0.2 mg/kg IV (umbilical or jugular) every 3–5 minutes
-Do not use atropine
What are some things you need to do for a neonate
Umbilical cord will need to be ligated and cleaned
Treat hypoglycemia
Dextrose by mouth or IV
Re-unite with dam ASAP, do not leave puppies alone with an ataxic dam.
How to increase success of live puppies
Planned C-section is better than emergency
Decrease anesthetic time
Maintain uterine perfusion and oxygenation
Train all staff on how to assist in neonate resuscitation
Dam awake and nursing quickly after surgery
Have a quiet, stress-free area for recovery
Exam room?
Cover cage with a towel and minimize interactions
