We have studied, in 37 adult patients, the anatomy of the sacral extradural (caudal) space using magnetic resonance imaging. The sacrococcygeal membrane (SCM) could not be detected in 10.8% of patients. The maximum depth of the caudal space adjacent to the SCM was beneath the upper third of the SCM in more than 90% of patients (mean depth 4.6 mm; range 1.0-8.0 mm). The shortest linear distance from the dura to the upper limit of the SCM varied considerably (60.5 mm; 34-80 mm) as did the volume of the caudal space excluding the foraminae and dural sac (14.4 cm3; 9.5-26.6 cm3). The dimensions of the caudal space and their variability have implications for clinical practice and a knowledge of these dimensions may increase both the reliability and safety of caudal techniques in adult patients.

Opioid analgesics have pharmacological effects in many organ systems, including the eye. Because the metabolites of morphine and codeine contribute to their overall pharmacological effect pupil diameter measurements were made over a 6-h period. We studied the pupillary effects of IV morphine (0.125 mg/kg), codeine (1 mg/kg), tramadol (1.25 mg/kg), or placebo (10 mL 0.9% w/v sodium chloride) in 10 healthy volunteers. Pupil diameter was measured every 30 min using a pupil densitometer. Comparisons of the change in pupil diameter for each drug were made using analysis of variance with repeated measures. No significant change in pupil diameter was observed after placebo. After IV morphine and codeine administration there was a 26% decrease in pupil diameter (P < 0.001). Over the course of the study period, pupil diameter gradually returned to baseline values. After administration of tramadol there were no significant changes in pupil diameter until 150 min after administration, after which there was a significant reduction for the remainder of the study period (P < 0.01). The changes in pupil diameter may be explained in part by the pharmacokinetic profiles of the opioids studied. Measurement of pupil diameter may have a place in monitoring the central effect of opioids.

We have evaluated the morphine-sparing effect of rectal paracetamol during the first 24 h after abdominal hysterectomy in a placebo-controlled, double-blind study. We studied 72 patients receiving patient-controlled analgesia (PCA) with i.v. morphine after a standardized anaesthetic, allocated randomly to receive rectal paracetamol 1.3 g, diclofenac 50 mg or placebo, after wound closure and at 8 and 16 h. Suppositories were blinded by the hospital pharmacy. Study violations excluded data from seven patients. Patient data, morphine doses during anaesthesia and recovery, and sedation and nausea scores were comparable. Mean morphine consumption during PCA was 35.0 (SD 20.4) mg, 32.7 (27.4) mg and 54.9 (28.3) mg in the paracetamol (n = 24), diclofenac (n = 20) and placebo (n = 21) groups, respectively (P < 0.05). Morphine sparing during PCA for paracetamol and diclofenac (36% vs 40% over 24 h) was significant from 4 h. Global scores of average pain over 24 h were lower after diclofenac compared with paracetamol (P < 0.01) and placebo (P = 0.08). We conclude that rectal paracetamol was an efficacious adjuvant analgesic after regular dosing.

Objectives To determine whether preoperative dexamethasone reduces postoperative vomiting in patients undergoing elective bowel surgery and whether it is associated with other measurable benefits during recovery from surgery, including quicker return to oral diet and reduced length of stay. Design Pragmatic two arm parallel group randomised trial with blinded postoperative care and outcome assessment. Setting 45 UK hospitals. Participants 1350 patients aged 18 or over undergoing elective open or laparoscopic bowel surgery for malignant or benign pathology. Interventions Addition of a single dose of 8 mg intravenous dexamethasone at induction of anaesthesia compared with standard care. Main outcome measures Primary outcome: reported vomiting within 24 hours reported by patient or clinician. Secondary outcomes: vomiting with 72 and 120 hours reported by patient or clinician; use of antiemetics and postoperative nausea and vomiting at 24, 72, and 120 hours rated by patient; fatigue and quality of life at 120 hours or discharge and at 30 days; time to return to fluid and food intake; length of hospital stay; adverse events. Results 1350 participants were recruited and randomly allocated to additional dexamethasone (n=674) or standard care (n=676) at induction of anaesthesia. Vomiting within 24 hours of surgery occurred in 172 (25.5%) participants in the dexamethasone arm and 223 (33.0%) allocated standard care (number needed to treat (NNT) 13, 95% confidence interval 5 to 22; P=0.003). Additional postoperative antiemetics were given (on demand) to 265 (39.3%) participants allocated dexamethasone and 351 (51.9%) allocated standard care (NNT 8, 5 to 11; P<0.001). Reduction in on demand antiemetics remained up to 72 hours. There was no increase in complications. Conclusions Addition of a single dose of 8 mg intravenous dexamethasone at induction of anaesthesia significantly reduces both the incidence of postoperative nausea and vomiting at 24 hours and the need for rescue antiemetics for up to 72 hours in patients undergoing large and small bowel surgery, with no increase in adverse events. Trial registration EudraCT (2010-022894-32) and ISRCTN (ISRCTN21973627).

More than half of the patients with symptoms of colorectal cancer are found to have extracolonic pathologies by CTC analysis. However, the proportion of patients found to have extracolonic malignancies after 1 year of CTC examination is not significantly greater than after barium enema or colonoscopy examinations. International Standard Randomised Controlled Trials no: 95152621.isrctn.com.