Predictive Value of Noninvasive Hemodynamic Parameters For Post-Induction Hypotensionin Pregnant Women With Placenta Previa: A Review Article

Abstract

During pregnancy, anatomical and physiological changes occur to meet the increased metabolic needs, to permit appropriate development of fetus and to prepare the body for childbirth. The changes begin to occur early in the first trimester, peaking at the term or labour and revert to pre-pregnancy levels by a few weeks into the postpartum. Pregnancy induces significant cardiovascular adaptations beginning as early as the 8th week of gestation. Increased estrogen and progesterone levels cause peripheral vasodilation and reduced systemic vascular resistance, requiring an increase in cardiac output to maintain adequate blood pressure. Pregnancy causes several physiological changes in the respiratory system. Estrogen-induced capillary engorgement leads to edema of the nasal, oropharyngeal, and laryngeal mucosa, while enlargement of the thoracic cage increases chest dimensions. Increased metabolic demands result in higher carbon dioxide production and a rise in minute ventilation, reducing arterial carbon dioxide tension (PaCO₂) to 30–32 mmHg and producing a mild, compensated respiratory alkalosis with decreased serum bicarbonate levels