Created October 24, 2018, last updated over 1 year ago.
Collection: 92, Score: 1112, Trend score: 0, Read count: 1112, Articles count: 9, Created: 2018-10-24 23:40:40 UTC. Updated: 2021-02-09 00:08:21 UTC.
Is the conventional assumption that left-lateral tilt and uterine displacement avoids aortocaval compression during Caesarean section actually valid?
50 years of assumed orthodoxy is challenged by studies showing that:
- True aortal compression is relatively uncommon (Higuchi 2015, Lee 2012).
- Caval compression is probably near-universal, but also usually not improved by a mere 15 degree tilt. (An impractical 30 degrees is more likely required for meaningful impact!) (Palmer 2015).
- Caval compression probably has limited haemodynamic or fetal consequences in the fit, well, term parturient (Higuchi 2015; Lee 2012).
- Judicious use of vasopressor infusions may obviate the need for traditional uterine displacement (Lee 2017; Farber 2017).
Time to change practice then?
Not quite yet...
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Randomized Controlled Trial
Review Meta Analysis
During caesarean section mothers can be in different positions. Theatre tables could be tilted laterally, upwards, downwards or flexed and wedges or cushions could be used. There is no consensus on the best positioning at present. ⋯ There is limited evidence to support or clearly disprove the value of the use of tilting or flexing the table, the use of wedges and cushions or the use of mechanical displacers. A left lateral tilt may be better than a right lateral tilt and manual displacers may be better than a left lateral tilt but larger studies with more robust data are needed to confirm these findings.
Patients in the third trimester of pregnancy presenting to the emergency department (ED) with hypotension are routinely placed in the left lateral tilt (LLT) position to relieve inferior vena cava (IVC) compression from the gravid uterus thereby increasing venous return. However, the relationship between patient position and proximal intrahepatic IVC filling has never assessed directly. This study set out to determine the effect of LLT position on intrahepatic IVC diameter in third trimester patients under real-time visualization with ultrasound. ⋯ IVC ultrasound is feasible in late pregnancy and demonstrates an increase in diameter with LLT positioning. However, a quarter of patients had a decrease in IVC diameter with tilting and, instead, had the largest IVC diameter in the supine position suggesting that uterine compression of the IVC may not occur universally. IVC assessment at the bedside may be a useful adjunct in determining optimal positioning for resuscitation of third trimester patients.
Randomized Controlled Trial
Aortocaval compression (ACC) can result in haemodynamic disturbances and uteroplacental hypoperfusion in parturients. Its detection is difficult because in most patients, sympathetic compensation results in no signs or symptoms. However, profound hypotension may develop after sympathectomy during regional anaesthesia. In this prospective observational study, we aimed to detect ACC by analysing haemodynamic changes in term parturients who were positioned sequentially at different angles of lateral tilt. ⋯ Patients with ACC can be identified by the CO changes from serial measurements between supine, 15°, or full lateral tilt. Our findings suggest that in non-labouring parturients, ACC is asymptomatic and can be effectively minimized by the use of a left lateral tilt of 15° or greater.
Randomized Controlled Trial Comparative Study Clinical Trial
Sixty healthy women undergoing elective Caesarean section were randomly allocated to either a measured 15 degrees left table tilt position (n = 31) or full left lateral position (n = 29) for a 15-min period after spinal blockade. Arm and leg blood pressure, ephedrine requirements, symptoms, fetal heart rate, cord gases and Apgar scores were recorded. ⋯ Differences in maternal nausea, vomiting and bradycardia and fetal outcome were not statistically significant. Following spinal anaesthesia, even a true 15 degrees left table tilt position is associated with aortic compression.
Randomized Controlled Trial Comparative Study
Lateral table tilt or a pelvic wedge are commonly used to reduce inferior vena cava compression during obstetric anaesthesia in the supine position. Direct measurement of pelvic angle allows individual assessment of the effectiveness of these manoeuvres in achieving a tilted position. We observed routine practice during caesarean section after random allocation to one or other of these methods. ⋯ There was a significant difference between table angle and pelvic angle in the women with table tilt (p = 0.0003), but no significant difference in pelvic angle between the table tilt and wedge groups. Measurement of table angle does not represent pelvic position adequately in the majority of women. However, this study showed that lateral table tilt and a pelvic wedge were equally effective in producing tilt of the pelvis.