Maternal hypotension during spinal anesthesia for caesarean delivery.

The aim of the study was to review maternal hypotension during caesarean delivery with spinal anesthesia. Obstetric complications, such as obstetric hemorrhage and problems related to concomitant maternal diseases are not considered. Reports of hypotension during spinal anesthesia for elective caesarean delivery are frequent (70-80%) when pharmacological prophylaxis is not used. Although some physical methods (leg wrapping, thromboembolic stockings) and the prevention of aorto-caval compression (left lateral tilt of the uterus) are useful, main prevention relies on two pharmacological methods, vasopressor therapy and intravascular fluid loading generally in combination. Ephedrine has been the vasopressor of choice in obstetrics for decades but phenylephrine is now the preferred first line approach during elective procedures at least. Crystalloid preloading is clinically ineffective and should be abandoned. Crystalloid coloading at the onset of sympathetic blockade is better but its efficacy may depend on the volume infused and the speed of administration. Preloading with hydroxyethylstarch is more consistently effective in reducing the incidence and severity of hypotension and hydroxyethylstarch coloading appears equally effective. Preoperative tests and new monitoring devices are available to predict or permit early detection of hypotension, but their feasibility and reliability in routine clinical practice is not yet established. With these tools, it may become possible to tailor prophylaxis to the assessed risk of the individual. Combining a prophylactic vasopressor regimen with hydroxyethylstarch preloading, hydroxyethylstarch coloading or crystalloid coloading is the best method to decrease the incidence and severity of hypotension during spinal anesthesia for caesarean delivery.