A Trial of the Use of Ultrasound to Aid the Insertion of Combined Spinal Epidural Anaesthesia

The study will establish whether the use of ultrasound scanning with a purpose built probe will aid the insertion of the needles for epidural and spinal anaesthesia for obese women undergoing elective caesarean section The study group will be 46 obese women (defined by the ratio of height to weight) at time of initial booking ultrasound scan, undergoing routine caesarean section with no serious illnesses that are both willing and able to provide informed consent prior to spinal epidural anaesthesia. Patients will be excluded if they have signs or symptoms of systemic or local infection, if they have a history of previous spinal surgery, a blood clotting abnormities. In order to evaluate the clinical usefulness of the ultrasound probe a randomised comparison of the traditional clinical methods of feeling the bones of the spine and ultrasound guided insertion of a combined spinal epidural anaesthetic will be undertaken. The rodiera tiped 17/18G 90mm tuohy needle and 123mm 27G spinal needle manufactured by Sarstedt will be the regional needles used for the combined spinal epidural anaesthetic. Randomisation into two groups (ultrasound guided needle insertion and feeling the bones) will be by computer generated random sequence. This information will be recorded in sealed envelopes and placed in the ward. Patients who meet the inclusion criteria and who consent immediately prior to caesarean section will be sequentially assigned a number that will correspond to a sealed envelope. The main aim of the study will be to detect any difference in time taken to insert epidural catheter via the needle in the patients back. The other factors measured will be the number of times the skin is punctured and bone touched by the needle, number of conversions from regional (spinal epidural) to general anaesthesia, patient satisfaction scores, requirement for extra local anaesthetic following initial blockade during Caesarean section. The factors will be compared by student t-test using Statistica6 (StatSoft,Inc.(2001). STATISTICA (data analysis software system), version 6. www.statsoft.com). A population of 46 patients will be required assuming a mean time for inserting a combined spinal epidural without