V1v: Physiological consequences of supine position in pregnancy
Cardiovascular
- Overall increase in CO, SV, HR to accommodate physiological changes of pregnancy
- Supine position reduces CO with almost complete occlusion IVC & lateral displacement of subrenal aorta when supine due to compression by pregnant uterus
- Improves with L) lateral position which displays the greatest CO & SV
Aortocaval Compression Syndrome
- Compression of Aorta & IVC by pregnant uterus
- Reduction in CO
- Compensation by sympathetic activation
- Pallor, dizziness, hypotension, diaphoresis, nausea & LOC
- Resolution w L) lateral tilt
Respiratory
- Narrowing of upper airway by 3rd trimester
- OSA & snoring when supine
- Marked reduction in FRC 70% !
Renal
- Complete IVC occlusion at level of renal vein entry
- Increase in renal venous pressure
- Oliguria
MSK
- Lower back pain