Table 1

Principal features to consider when treating unhealthy pregnant women

Disease	Features and/or indications
Asthma [15]	Recommended use of corticosteroids to prevent critical illness
Asthma [15]	Oral corticosteroids associated with a two-fold increase in pre-eclampsia and with a minimal incidence (0.4%) +of oral clefts (if taken in the first trimester)
Pulmonary oedema [15]	Cardiogenic basis secondary to haemodynamic factors occurring during pregnancy:
	↑ cardiac output
	↑ heart rate
	↓ systemic vascular resistance
	↓ colloid osmotic pressure
	A consequence of tocolytic therapy and of pre-eclampsia
	If no improvement within 24 h after diuresis, invasive haemodynamic monitoring and/or rapid antihypertensive therapy are required
Severe restrictive lung disease [10]	Risk of hypoxic and hypercapnic respiratory failure because the ability to increase ventilation is limited
	Severely reduced vital capacity but pregnancy can be well tolerated
	Minimal complication: preterm delivery with newborn needing high-dependency support
	Lung function and oxygen saturation should be monitored
	Supplemental oxygen and noninvasive ventilation may be required
Pre-eclampsia [16]	The most common obstetric disorder, with multisystem ramifications
	↑ minute ventilation because of ↑ concentration of blood leptin (a ventilation-stimulating hormone)
	↓ vital capacity secondary to lower transverse section area of the upper airways, pharyngeal oedema and excessive weight gain with higher adipose deposition around the neck
	↓ exercise tolerance
	Respiratory muscle function is not affected
Heart and lung transplantation [17]	Better to avoid conception within the first 1–2 years after transplantation
	Potential pregnancy-related complications: prematurity, low weight at birth and postpartum graft loss
	Maintenance of immunosuppression with close monitoring of cyclosporine blood levels during gestation
	Accurately diagnose signs of pre-eclampsia, as it is a multi-organ disease
Hereditary neuromuscular disorders [18]	Identify the highest risk group according to the diaphragmatic and/or bulbar involvement of the disease
	↑ respiratory muscle load by higher airway resistance and impaired bulbar load, leading to overwhelmed respiratory muscle capacity
	Hypoventilation
	Monitor the respiratory and cough function
	Maximise airway clearance
	High aspiration risk in the third trimester because of ↑ abdominal pressure and ↓ gastro-oesophageal sphincter tone
ARDS [19]	Non-obstetric causes: sepsis, pneumonia, intracerebral haemorrhage, blood transfusion and trauma
	Obstetric causes: amniotic fluid embolism, pre-eclampsia, septic abortion, retained products of conception and complication from tocolytic therapy
	Management includes: prompt antibiotic therapy, conservative fluid strategy, use of mechanical ventilation and extracorporeal life support in case of refractory ARDS
Mechanical ventilation [20]	Similar indications to those for non-pregnant patients, with some exceptions:
	Oxygen therapy may also help fetal distress
	Consider that P_CO₂ in pregnancy is about 30 mmHg when interpreting arterial blood gases
	Airways are narrow (consequence of mucosal surface hyperaemia), so it is preferable to perform endotracheal intubation via oral route using a smaller tube
	↓ oxygen reserve of the mother, so use pre-oxygenation with 100% oxygen during intubation to avoid arterial desaturation after a short period of apnoea
	Better to avoid respiratory alkalosis as it leads to problems in uterine blood flow and fetal oxygenation
	Treat respiratory acidosis with bicarbonate

ARDS: acute respiratory distress syndrome; ↑: increased; ↓: decreased.