Studies of the Inferior Vena Cava in Late Pregnancy

Kerr, M. G.; Scott, D. B.; Samuel, Eric

doi:10.1136/bmj.1.5382.522

Cited by 233 publications

(66 citation statements)

References 2 publications

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“…In pregnant mothers, the gravid uterus causes compression of the inferior vena cava and partial obstruction of the aorta [1,7]. These effects result in a reduced venous return, a fall in cardiac output and a decrease in systemic blood pressure.…”

Section: Discussionmentioning

confidence: 99%

Hypotension following combined spinal‐epidural anaesthesia for Caesarean section

et al. 2003

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SummaryEighty-seven pregnant mothers undergoing elective Caesarean section were randomly allocated either to the full left lateral position (n ¼ 45) or to the supine position with 12°left lateral tilt (n ¼ 42) after a combined spinal-epidural (CSE) in the sitting position and an initial 2 min in the full right lateral position. Fewer mothers were hypotensive while in the study position [29 (64%) in lateral group vs. 38 (90%) in the tilted supine group; p ¼ 0.03]. Mothers in the lateral group tended to become hypotensive after turning them back to the tilted supine position immediately before surgery; hence the number of mothers who were hypotensive from the insertion of the CSE until delivery were similar [36 (80%) vs. 38 (90%)

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Section: Discussionmentioning

confidence: 99%

Hypotension following combined spinal‐epidural anaesthesia for Caesarean section

et al. 2003

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“…In 1964, Kerr et al [11] demonstrated using radiological methods that the inferior vena cava was partially occluded in late pregnancy if the woman was placed in the supine position. In 1966, Bieniarz et al [12] demonstrated by simultaneous measurement of femoral and brachial arterial pressure that the aorta was also compressed in the supine position during late pregnancy.…”

Section: Discussionmentioning

confidence: 99%

“…Thus, aortocaval compression is a rule in late pregnancy in the supine position. It has been further demonstrated that the supine position can result in greater aortocaval compression than other positions such as left lateral decubitus, right lateral decubitus and upright positions [11,13,14].…”

Section: Discussionmentioning

confidence: 99%

Comparison of supine and upright positions on autonomic nervous activity in late pregnancy: the role of aortocaval compression

et al. 1999

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SummaryIn order to understand the effect of aortocaval compression on autonomic nervous activity, we compared the effects of supine and upright postures on measures of heart rate variability in late pregnancy. Thirty-two women in late pregnancy and 23 nonpregnant age-matched women were studied. Both time and frequency domain heart rate variability measures were compared between the supine and upright positions, and between pregnant women and controls. The pregnant women had smaller mean RR interval, standard deviation of RR intervals and normalised high-frequency power, and a larger low-to high-frequency power ratio than nonpregnant women in the supine position. When the position was changed from upright to supine in nonpregnant women, the percentage change in the mean RR interval and normalised high-frequency power were increased, whereas the percentage change in the coefficient of variation of RR interval and low-to high-frequency power ratio were decreased. In contrast, the percentage change in normalised high-frequency power was decreased and the percentage change in low-to high-frequency power ratio was increased in pregnant women when the position was changed from upright to supine. These results indicate that the vagal enhancing effect seen in normal subjects when changing position from upright to supine was reversed in women in late pregnancy. Aortocaval compression in the supine position in pregnant women might be responsible for this reversal in the autonomic response to lying down.

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“…ROBERTS [13] and HO-WARD et al [12] draw first attention to the fact, that the profound decrease in blood pressure observed by pregnant women in supine position in the last trimester is probably due to a reduced venous return to the maternal heart following vena caval occlusion. Radiological studies [4] showed that inferior vena cava is normally occluded in supine position in late pregnancy and venous return occures via azygos and vertebran vein. But these studies were concerned about maternal hemodynamics and maternal outcome.…”

mentioning

confidence: 99%