1 Southmead Hospital, North Bristol NHS Trust, Southmead Road, Westbury-on-Trym, Bristol BS10 5NB, UK. 2 St Michaels Hospital, St Michaels Hill, Bristol, UK E-mail: donald_fiona@hotmail.com
Accepted for publication: August 7, 2002
![]() |
Abstract |
---|
![]() ![]() ![]() ![]() ![]() ![]() |
---|
Methods. We measured the angle of table tilt used by 16 anaesthetists during uncomplicated, elective Caesarean section. After initiating anaesthesia, they were asked to position the patient and estimate the angle of tilt, which was then measured.
Results. Almost every anaesthetist positioned the patient less than 15° because they overestimated the angle of tilt. When questioned on their knowledge of the current advice for lateral tilt, 11 of the 16 anaesthetists were aware of the 15° recommendation.
Conclusion. Estimation of the angle of table tilt is unreliable.
Br J Anaesth 2003; 90: 867
Keywords: anaesthesia, obstetric; position, lateral tilt
![]() |
Introduction |
---|
![]() ![]() ![]() ![]() ![]() ![]() |
---|
The common recommendation is a 15° lateral tilt which was first described by Crawford and colleagues in 1972,2 and was achieved using a wedge. They demonstrated a significant improvement in fetal well-being when mothers were tilted rather than kept supine. However, the ideal amount of tilt varies with different mothers; the amount actually used is a compromise between patient and surgeon comfort and the perceived reduction in compression. Compression can occur even at more than a 15° angle, so it is best to use as much tilt as possible.3 Morgan and colleagues4 state that estimating angles by eye is grossly inaccurate, with the true angle being much smaller than the estimated one. However, whilst this might be an expected finding, no published work has demonstrated or quantified it in obstetric anaesthetic practice.
![]() |
Methods and results |
---|
![]() ![]() ![]() ![]() ![]() ![]() |
---|
Fifteen of the 16 Caesarean sections were performed under spinal anaesthesia, and one under general anaesthesia. The anaesthetists, who did not know the purpose of the study, positioned the patient and were then asked to estimate the degree of tilt that they had applied. The angle was measured using a protractor with a hanging weight. Finally, the anaesthetist was asked what the recommended angle of tilt was.
The measured table tilt was 715°; only one anaesthetist managed 15° (Fig. 1). Estimated tilt was 735°, and ten anaesthetists overestimated it by more than 10°. The four anaesthetists unaware of the 15° recommendation were among the most junior members of the department.
|
![]() |
Comment |
---|
![]() ![]() ![]() ![]() ![]() ![]() |
---|
Most of our anaesthetists thought they were using as much, or more than, the recommended degree of tilt. This is an important finding as it could make anaesthetists discount inadequate tilt as a cause of hypotension or collapse in a pregnant woman. Fitting operating tables with a simple device to measure the angle of tilt would act as both a reminder and a guide.
![]() |
References |
---|
![]() ![]() ![]() ![]() ![]() ![]() |
---|
2 Crawford JS, Burton M, Davies P. Time and lateral tilt at Caesarean section. Br J Anaesth 1972; 44: 47784[ISI][Medline]
3 Kinsella SM, Whitwam JG, Spencer JAD. Aortic compression by the uterus; identification with the Finapres digital arterial pressure instrument. Br J Obstet Gynaecol 1990; 97: 7005[ISI][Medline]
4 Morgan DJ, Paull JD, Toh CT, Blackman GL. Aortocaval compression and plasma concentrations of thiopentone at Caesarean section. Br J Anaesth 1984; 56: 34954[Abstract]
5 Bamber J. Aortocaval compression: the effect of changing the amount and direction of lateral tilt on maternal cardiodynamics. IJOA 2000; 9: 197
6 Pinder A, Bamber J, Dresner M. A cardiodynamic investigation of the use of lateral tilt during spinal anaesthesia. IJOA 2001; 10: 226