The role of cardiac output monitoring in obstetric anesthesia.

PURPOSE OF REVIEW: Haemodynamic monitoring in obstetric patients has evolved during the last decade, with the development of minimally invasive and noninvasive continuous cardiac output (CO) monitors. This review focuses on recent articles that improve our understanding of physiology and haemodynamic changes during spinal anaesthesia in healthy pregnant women, and pathophysiology in women with preeclampsia and other cardiovascular disease.

RECENT FINDINGS: Recent research findings in healthy women focus on the haemodynamic changes due to aortocaval compression, fluid administration, vasopressor therapy, and oxytocin during spinal anaesthesia for caesarean delivery. In preeclampsia, the haemodynamics of early versus late-onset disease and fluid management have been the subject of considerable investigation. Case reports suggest that invasive monitoring in combination with echocardiography is preferable for clinical management of high-risk obstetrics cases with unstable haemodynamics.

SUMMARY: In healthy women, left lateral tilt remains an important clinical intervention during caesarean delivery, and phenylephrine is an essential early adjunct to fluid therapy. Noradrenaline may have a clinical benefit in selected patients. Carbetocin has similar haemodynamic effects to oxytocin. Haemodynamic changes associated with delivery per se may be minor compared with those due to oxytocin. Uncomplicated severe preeclampsia is usually associated with a normal to raised CO. Early-onset preeclampsia may be associated with more vasoconstriction and lower CO than late-onset disease. Passive leg raising may be useful to judge fluid responsiveness, and lung ultrasound may predict pulmonary oedema in preeclampsia. Further research is warranted to study the area of circulatory changes during delivery and the postpartum period, in healthy and preeclamptic women.