The influence of posture upon cardiovascular dynamics throughout pregnancy

Atkins, A. J. F.; Watt, J. M.; Milan, P.; Davies, Paul; Crawford, J. Selwyn

doi:10.1016/0028-2243(81)90081-2

Cited by 31 publications

(5 citation statements)

References 12 publications

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“…The existing data from non-pregnant humans with regards to the effect of different positions on hemodynamic parameters are limited and sometimes conflicting. Some report that cardiac output is higher in the supine position compared to the right or left lateral position [12,13], while others have shown that cardiac output is higher in the left lateral position than in the supine position [14] and still others that there is no difference in either position [15,16]. In our series, we found that there was no significant effect on hemodynamic parameters and cardiac dimensions of moving from the supine to the left lateral position in non-pregnant women.…”

Section: Discussionmentioning

confidence: 99%

Quantitative cardiovascular magnetic resonance in pregnant women: cross-sectional analysis of physiological parameters throughout pregnancy and the impact of the supine position

Rossi

Cornette

Johnson

et al. 2011

Journal of Cardiovascular Magnetic Resonance

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BackgroundThere are physiological reasons for the effects of positioning on hemodynamic variables and cardiac dimensions related to altered intra-abdominal and intra-thoracic pressures. This problem is especially evident in pregnant women due to the additional aorto-caval compression by the enlarged uterus. The purpose of this study was to investigate the effect of postural changes on cardiac dimensions and function during mid and late pregnancy using cardiovascular magnetic resonance (CMR).MethodsHealthy non-pregnant women, pregnant women at 20th week of gestation and at 32nd week of gestation without history of cardiac disease were recruited to the study and underwent CMR in supine and left lateral positions. Cardiac hemodynamic parameters and dimensions were measured and compared between both positions.ResultsFive non-pregnant women, 6 healthy pregnant women at mid pregnancy and 8 healthy pregnant women at late pregnancy were enrolled in the study. In the group of non-pregnant women left ventricular (LV) cardiac output (CO) significantly decreased by 9% (p = 0.043) and right ventricular (RV) end-diastolic volume (EDV) significantly increased by 5% (p = 0.043) from the supine to the left lateral position. During mid pregnancy LV ejection fraction (EF), stroke volume (SV), left atrium lateral diameter and left atrial supero-inferior diameter increased significantly from the supine position to the left lateral position: 8%, 27%, 5% and 11%, respectively (p < 0.05). RV EDV, SV and right atrium supero-inferior diameter significantly increased from the supine to the left lateral position: 25%, 31% and 13% (p < 0.05), respectively. During late pregnancy a significant increment of LV EF, EDV, SV and CO was observed in the left lateral position: 11%, 21%, 35% and 24% (p < 0.05), respectively. Left atrial diameters were significantly larger in the left lateral position compared to the supine position (p < 0.05). RV CO was significantly increased in the left lateral position compared to the supine position (p < 0.05).ConclusionsDuring pregnancy positional changes affect significantly cardiac hemodynamic parameters and dimensions. Pregnant women who need serial studies by CMR should be imaged in a consistent position. From as early as 20 weeks the left lateral position should be preferred on the supine position because it positively affects venous return, SV and CO.

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Section: Discussionmentioning

confidence: 99%

Quantitative cardiovascular magnetic resonance in pregnant women: cross-sectional analysis of physiological parameters throughout pregnancy and the impact of the supine position

Rossi

Cornette

Johnson

et al. 2011

Journal of Cardiovascular Magnetic Resonance

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“…The leading cause for this is believed to be an increased vessel diameter in conjunction with an insufficient adaptation of the vascular autoregulation. Vasodilation during early pregnancy is supported by the trophoblastic invasion, estrogen and progesterone mediated relaxation of the venous smooth muscle tone, a reduced tone of the striated muscles and a marked shift in the production of prostaglandin derivatives from thromboxane to vessel dilating prostacyclin [2,8,10,11,12,15,24,25].…”

Section: Introductionmentioning

confidence: 99%

The implication of upright posture on pregnancy

Schneider

Deckardt²

1991

Jpme

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Pregnant women spend more than half of the day in an upright position. The physiological effects of this posture on the mother and the fetus are evaluated. Changes in vascular autoregulation and anatomy lead to maternal fainting in about 8% of women during early pregnancy. The immediate effects of such episodes on the fetus are unknown. There is a positive correlation of orthostatic dysregulations and abortions. In late pregnancy we found a significant increase in functional residual capacity in the upright posture. Minute volume and oxygen consumption were also significantly increase (p less than 0.001). Regarding the cardiovascular changes we detected a rhythmic change of the maternal heart rate with the change to upright position, which had not been published before. Change from the left lateral position to unsupported standing increased maternal heart rate by a mean of 27 beats per minute and a mean duration of 105 seconds in two thirds of the women. This was accompanied by a decreased cardiac output, systolic blood pressure and an increased oxygen consumption. The gravid uterus is responsible for these changes. During the upright position, the venous flow to the right ventricle is inhibited by the relaxed uterus. Contractions, leaning forward and the muscle pump improve the venous return. The phenomenon reached its maximum during the 38th week, where 71% of pregnant women displayed a cyclic change in heart rate. The fetal heart rate baseline is significantly increased in the upright position with a significantly reduced acceleration frequency (p less than 0.001). Combined with the data from epidemiologic studies, prolonged standing during late pregnancy may signal potential risks for the fetus such as low birth weight, prematurity and stillbirths because of an 'uterovascular syndrome'. Maternal standing possibly may be used as a physiological fetal stress test.

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“…When noninvasive methods are used in this position, however, the arms are at a different vertical level with respect to the heart. The uppermost arm has always been found to have a blood pressure lower than that measured while supine [4][5][6][7][8][9][10][11] or semirecumbent [8]. When blood pressure values have been reported in the dependent arm, they are usually similar to those in the supine [8][9][10][11] or semirecumbent [8] positions.…”

Section: Discussionmentioning

confidence: 99%

“…The blood pressure cuff is commonly placed on the uppermost arm because it is more accessible and because of a fear that, if it is on the dependent arm in the lateral position, it will be compressed leading to an inaccurate reading. Studies in nonlabouring women have shown that blood pressure taken in the uppermost arm in the lateral position is lower than that measured while supine [4][5][6][7][8][9][10][11].…”

mentioning

confidence: 99%

Reporting of ‘hypotension’ after epidural analgesia during labour

Kinsella

Black

1998

Anaesthesia

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SummaryWe studied 20 women in labour to see how reporting 'hypotension' after obstetric epidural analgesia is affected by position of the blood pressure cuff and baseline definition. Blood pressure was recorded from both arms simultaneously while the woman was semirecumbent and then in the left lateral position. Three readings were then taken after epidural bupivacaine, one left lateral and the remainder right lateral. Before the epidural, blood pressure in the dependent arm in the lateral position was similar to blood pressure in either arm in the semirecumbent position and an average of 10 mmHg (systolic) and 14 mmHg (diastolic) higher than blood pressure in the uppermost arm (p Յ 0.00005). This difference persisted in both lateral positions as epidural analgesia became established. Choosing different definitions of hypotension, baselines and arm to measure blood pressure resulted in 'hypotension rates' between 0% and 75%. For blood pressure measurement in the lateral position, the blood pressure cuff should be placed on the dependent arm. Hypotension after epidural analgesia during labour is of importance because of the direct link with impairment of uteroplacental blood supply [1]. Hypotension is often attributed to the sympathetic blocking effect of local anaesthetics, but has also been noted after spinal opioids, most of which do not have such an effect. For example, Ducey et al. [2] reported that 46% of women receiving a combination of spinal fentanyl and morphine for analgesia developed hypotension, defined by them as a decrease of more than 20% from baseline. This is considerably more frequent than might be expected after epidural analgesia and is hard to explain as a pharmacological effect.There are two alternative hypotheses to explain why hypotension might be so commonly diagnosed after regional analgesia during labour. Blood pressure increases with the onset of labour as a consequence of painful contractions, and the use of a prelabour value as a baseline has been found to influence the hypotension rate [2,3]. The lateral position is often used in labour to avoid the maternal and fetal effects of supine aortocaval compression, and there must inevitably be a hydrostatic difference in the blood pressure recorded between the uppermost and dependent arms. The blood pressure cuff is commonly placed on the uppermost arm because it is more accessible and because of a fear that, if it is on the dependent arm in the lateral position, it will be compressed leading to an inaccurate reading. Studies in nonlabouring women have shown that blood pressure taken in the uppermost arm in the lateral position is lower than that measured while supine [4][5][6][7][8][9][10][11].We investigated these two influences on recording of blood pressure and hypotension rate after epidural analgesia during labour. Methods

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The influence of posture upon cardiovascular dynamics throughout pregnancy

Cited by 31 publications

References 12 publications

Quantitative cardiovascular magnetic resonance in pregnant women: cross-sectional analysis of physiological parameters throughout pregnancy and the impact of the supine position

Quantitative cardiovascular magnetic resonance in pregnant women: cross-sectional analysis of physiological parameters throughout pregnancy and the impact of the supine position

The implication of upright posture on pregnancy

Reporting of ‘hypotension’ after epidural analgesia during labour

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