ICU · Obs/Gynae

Acute severe community-acquired pneumonia: special populations — pregnancy

Also known as CAP in pregnancy · Pneumonia in pregnant ICU patients · Maternal critical care · Varicella pneumonia in pregnancy · Influenza pneumonia in pregnancy · Pneumonia in pregnancy

CAP in pregnancy has higher morbidity and mortality than non-pregnant CAP — it is the 1 non-obstetric infection requiring ICU admission in pregnancy. Three converging mechanisms transform a 'standard' pneumonia into a time-critical maternal illness: (1) IMMUNOSUPPRESSION — pregnancy suppresses cell-mediated (Th1) immunity, increasing susceptibility to viral (influenza, varicella, CMV), intracellular (Legionella, Mycoplasma), and fungal (Coccidioides, Pneumocystis) pathogens; (2) RESPIRATORY PHYSIOLOGY — the gravid uterus elevates the diaphragm, reducing functional residual capacity (FRC) by ~20% while oxygen consumption rises 20-30%, so the apnoeic/fasted pregnant patient desaturates in seconds; (3) CARDIOVASCULAR PHYSIOLOGY — cardiac output and oxygen demand are already near-maximal (little reserve), and aortocaval compression in the supine position collapses preload and placental perfusion. Organisms: S. pneumoniae (1, ~two-thirds of bacterial CAP), H. influenzae, atypicals (Mycoplasma, Legionella); viral pathogens are disproportionately severe — pandemic H1N1 influenza (7x higher mortality in pregnancy; the third trimester is deadliest), varicella pneumonia (10-25x higher mortality — the classic exam killer), and SARS-CoV-2. Management: LOWER threshold for ICU; oxygen target SpO2 95% (fetal oxygenation is entirely dependent on maternal PaO2); LEFT LATERAL TILT from 20 weeks; MG-SAFE antibiotics (beta-lactams + macrolides safe; AVOID tetracyclines/aminoglycosides/quinolones); oseltamivir SAFE and given EARLY (within 48h) for influenza; aciclovir IV for varicella; continuous fetal monitoring (CTG) if viable; deliver the deteriorating mother.