Non-Obstetric Surgery In A Pregnant Patient

Question 1

A 26-year-old female is booked onto the emergency theatre list for drainage of a perianal abscess. She is 30 weeks pregnant.

What added information would you like prior to proceeding with this case?

Answer 1

MDT approach - increased maternal and foetal risks

Anaesthetic, surgical and obstetric factors

Anaesthetic factors:

• This patient should be reviewed and managed by a senior anaesthetist, conducting a thorough history and examination to determine her comorbidities and risk factors. In addition, take an obstetric history including parity, gestation and any complications of pregnancy.
• The main anaesthetic concerns in this patient are:
• Increased risk of difficult airway and failed intubation.
• Avoidance of foetal distress and hypoxia through maintenance of
  maternal physiology.
• Aortocaval compression.
• Risk of premature labour.
• Care to minimise foetal exposure to medications, and in particular, avoid medications that are known to be harmful to the foetus or increase the risk of premature labour.

Question 2

What added information would you like prior to proceeding with this case?

Continued…

Answer 2

Surgical factors:

• The patient should be reviewed by a consultant surgeon and the procedure should be delayed if it is not necessary, while recognising that untreated maternal infection can be harmful to the foetus and that foetal wellbeing is ultimately linked to maternal wellbeing.
• If surgery is essential, it should be performed by a senior surgical team.

Question 3

What added information would you like prior to proceeding with this case?

Continued…

Answer 3

Obstetric factors:

• The obstetric team should be aware that this patient is undergoing surgery, and a consultant obstetrician should be informed.
• If appropriate, perioperative foetal monitoring should be conducted by a senior midwife. Most commonly, this means assessing foetal wellbeing by listening to the foetal heart rate pre- and post procedure. Very occasionally the CTG may be monitored intraoperatively, but it is difficult to interpret if the foetus has also been anaesthetised by the anaesthetic drugs administered to the mother. If intraoperative monitoring is used, a plan should be made of the appropriate course of action if an abnormal CTG is detected. This may vary from simply checking that maternal physiology is optimised, to proceeding to immediate caesarean delivery. If the latter is considered, then all the appropriate teams and equipment must be immediately to hand.
• Consideration of steroids for foetal lung maturation in case of premature labour, and the likelihood of delivery is considered to be high.

Question 4

If a general anaesthetic is used, the standard for airway control would be tracheal intubation.

What factors increase the risk of a difficult airway in this patient?

Answer 4

• Anatomical: increased breast tissue, airway oedema, and left lateral positioning leading to an altered view with laryngoscopy.
• Physiological: decreased functional residual capacity and increased oxygen demand, allowing less time for intubation prior to desaturation.
• Human factors: increased stress and anxiety, limited experience managing obstetric patients under general anaesthesia.

Question 5

How would you conduct the induction of anaesthesia this patient?

Answer 5

• Ensure emergency drugs and equipment checked including the difficult airway trolley, attach AAGBI monitoring, machine check and patient consent/WHO checklist complete.
• Preparation for rapid sequence induction: trained assistant; senior support; discussion of the airway plan including the plan in the event of a failed intubation; cricoid pressure; suction switched on and accessible; antacid prophylaxis; and appropriate positioning of the patient (head up with left lateral tilt).
• Consider using a videolaryngoscope first-line.

Question 6

How would you conduct the induction of anaesthesia this patient?

Answer 6

• Pre-oxygenation with 100% for 3 minutes targeting an end tidal oxygen concentration of >85%.
• Induction of anaesthesia with propofol (1.5–2 mg/kg) and suxamethonium (2 mg/kg), with cricoid pressure. Consider an opiate at induction (1–2 mcg/kg fentanyl, or equivalent); the opiate does not pose a risk to the foetus as delivery is not expected, and the risk of a hypertensive response to laryngoscopy is increased in pregnant women, particularly if hypertensive diseases of pregnancy are present.
• Tracheal intubation of the patient with an appropriately sized endotracheal tube (OAA/DAS guidelines recommend a size 7.0mm ETT as the default for pregnant women); confirmation of placement and maintenance of anaesthesia with sevoflurane/oxygen/air mixture.

Question 7

In the case of a failed intubation, what factors would favour proceeding with this particular surgery rather than waking the patient up?

Answer 7

• The Difficult Airway Society has produced a specific obstetric intubation guideline and algorithm that guides the anaesthetist in this situation.
• Factors that would encourage waking the patient include:
• No maternal or foetal compromise.
• Junior anaesthetist.
• Very high BMI.
• Complex or prolonged surgery.
• Patient not fasted.
• Factors that favour proceeding with surgery are:
• Severe maternal or foetal compromise with a threat to life.
• Consultant anaesthetist.
• Successful placement of 2nd generation supraglottic airway device.
• Fasted patient with minimal comorbidities.
• In this particular scenario, in the case of failed intubation, it would be prudent to follow the difficult airway algorithm, which includes calling for urgent senior help, attempting supraglottic airway device insertion and facemask ventilation, and early consideration of waking the patient.