Influenza and Pregnancy

SPECIFIC CHALLENGES

• known high incidence of morbidity and mortality in mother and foetus in H1N1 infection and severe community acquired pneumonia.
• multidisciplinary team approach: O&G, NICU, anaesthetics, ICU
• planned delivery of foetus (although the teams may have conflicting interests)
• indication for intubation: if respiratory failure, hypoxaemia, hypercapnia, exhaustion.
• high risk intubation: aspiration, difficult airway, narrow airway, worsening acidosis, cardiac arrest.
• difficulties ventilation and complication of ventilation: pneumothorax, tension, cardiac arrest, increased airway pressures, watch intrinsic PEEP, high pressures may reflect raised intra-abdominal pressures.
• importance of keeping family members well informed of considerations and likelihood of possible poor foetal outcome as priority will be given to mother’s survival.

MOTHER

• physiologic changes of pregnancy: respiratory/cardiovascular, aortocaval compression syndrome.
• need to be aware of the changes in blood gas reference values.
• need to position carefully -> ideally left lateral position.
• pregnancy can worsen respiratory failure– pulmonary congestion, reflux disease, low FRC
• reduced respiratory reserve – > decompensation can be rapid
• hx of pregnancy: gestational age, singleton?, size of baby / polyhydramnios?
• does baby impair mothers state / ventilation
• protective ventilation and permissive hypercapnoea -> significant foetal acidosis
• safety of various drugs in pregnancy (antivirals, sedatives)

FOETUS

• viable?
• lung development possible/betamethasone considered?
• effect of medication given to mother:

-> Steroids – potential malformations in the fetus if used in the first trimester – cleft lip
-> Benzodiazepines – floppy infant syndrome
-> Opiates- fetal respiratory depression
-> Prolonged paralysis – risk of arthrogryposis in the fetus

• maternal hypercapnia – reduces uteroplacental blood flow + shifts oxyHb dissociation curve in the fetus to the right -> thus impairing fetal oxygenation – fetal monitoring essential
• long term maternal hypoxia associated with IUGR

MANAGEMENT

Resuscitate

A: secure early, RSI, anticipate that it may be difficult and prepare adequately including calling for help
B: head up, protective lung strategy, but limiting hypercapnoea if possible (SIMV, FiO2 1.0, TV 6-7mL/kg, low rate, I:E 1 to 3, PEEP 10-15cmH2O titrated to oxygenation, paralyse)
C: fluid resuscitate to clinical endpoints, invasive monitoring, vasoactive agents to maintain MAP > 60mmHg, may require Q monitoring, left lateral position

Acid-base and Electrolytes

• respiratory acidosis -> manipulation of ventilation
• metabolic acidosis -> treatment of sepsis

Specific Therapy

• oseltamivir
• IV antibiotics to cover possible superinfection
• steroids for baby
• planned triggers for delivery -> may require it urgently
• consideration for adjuncts: iNO, HFOV, (prone and ECMO contraindicated)
• monitoring for pulmonary and extra-pulmonary complications