Impact of manual uterine displacement and left lateral tilt on echocardiographical velocity time intergral (stroke volume) in advanced pregnancy
Background. Pregnant women undergo a variety of physiological changes, and cardiac output (CO) is one of these important changes. During advanced pregnancy, aortocaval compression decreases CO by up to 30 - 40%. Such compression may cause adverse physiological disturbances in both the mother and the baby. Current practice is to nurse pregnant woman with at least 15° lateral tilt. Most studies have used non-invasive blood pressure measurement, which is not the gold standard and does not give a true depiction of the cardiac response to change in position.
Objective. To determine the impact of manual uterine displacement (MUD) on cardiac stroke volume (SV) using the current most accurate non-invasive method, i.e. descending aorta velocity time integral (VTI) with echocardiography (ECHO). This method was used to ascertain the appropriate position to improve CO and provide superior uterine perfusion.
Methods. A prospective case crossover study consisting of 22 women at 36 - 40 weeks of gestation was conducted. The studied positions were supine, 30° tilt, left lateral tilt and manual uterine displacement. Patients received a screening ECHO to ensure normal cardiac structure and function followed by measurement of the descending aorta VTI at each of the positions with 2-minute intervals between position changes.
Results. There was a significant increase in the aortic VTI with all changes in position. The mean (standard deviation (SD)) change for supine-left lateral was 3.68 (0.74) (p=0.00), supine-MUD was 3.29 (0.72) (p=0.00) and supine-30° was 2.93 (0.72) (p=0.00). No significant difference was found when the positions were compared with each other.
Conclusion. Lateral tilt and MUD significantly increased descending aorta VTI (SV).
K A Knipe, Department of Obstetrics and Gynaecology, Tygerberg Hospital and University of Stellenbosch, Cape Town, South Africa
E J Langenegger, Department of Obstetrics and Gynaecology, Tygerberg Hospital and University of Stellenbosch, Cape Town, South Africa
W Muller, Department of Medicine, Tygerberg Hospital and University of Stellenbosch, Cape Town, South Africa
P Herbst, Department of Medicine, Tygerberg Hospital and University of Stellenbosch, Cape Town, South Africa
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Date published: 2020-12-15
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