We analyzed data from 1233 Chinese patients of a wide age range who received patient-controlled analgesia (PCA) intravenous morphine for postoperative pain relief, during the period from January 1992 to May 1995. The analgesic regimen was standardized as follows: PCA bolus 1 to 1.5 mg; lock-out interval 5 minutes; one-hour maximum dose 0.075 to 0.1 mg.kg -1 and background infusion 0 or 0.5 mg.h -1 . Most patients underwent major surgery that was broadly subclassified according to the anatomical area involved. The median verbal numerical rating scales of pain (0 to 10) at rest and while coughing for the first, second and third 24 hours were 3.0/5.0, 1.5/4.0 and 0/3.0 respectively and the corresponding demand to delivery ratios were 2.8±2.9, 2.6±2.4 and 2.4±2.6. The overall morphine consumptions in 1004 of these Chinese patients were 27.5±16.8, 17.8±16.1 and 18.1±21.0 µg.kg -1 .h -1 during the first 16, 17 to 41 and 42 to 66 postoperative hours respectively. These figures were the same as for Caucasian patients managed in the same institution. Morphine consumption was significantly higher following thoracic, upper abdominal and spinal surgery. Also it was higher in patients younger than 65 years, males, cigarette smokers and those with ASA physical status I or II. The commonest side-effects were nausea (34.5%) and vomiting (18.2%). Bradypnoea and oxygen desaturation occurred in 0.5% and 1.6% respectively. All cases were promptly detected and managed with no adverse outcomes. Most patients were satisfied (76.7% ranked "good") with their postoperative analgesia. The commonest reasons for dissatisfaction were inadequate pain relief, nausea and reluctance to selfcontrol analgesic administration. It is concluded that PCA with intravenous morphine is effective and safe as a routine postoperative technique for Chinese surgical patients.

as non-CTEPH and three MRI were considered non-diagnostic. MR lung perfusion was not performed in 11 patients due to impaired renal function or patient unable to tolerate breathhold. None of the surgically accessible disease was missed with either modality. The MR lung perfusion had a sensitivity of 96%, specificity of 92%, PPV of 87%, NPV of 98% and accuracy of 94% for diagnosing CTEPH. Perfusion scintigraphy had a sensitivity of 93%, specificity of 90%, PPV of 83%, NPV of 96% and accuracy of 91%. Conclusion Our results show that MR lung perfusion compared to 4-view static perfusion scintigraphy has an overall higher accuracy compared to perfusion scintigraphy and has a role in assessment of patients with suspected CTEPH. Background The incidence of pulmonary hypertension (PH) after an episode of acute pulmonary embolism (PE) is thought to be up to 4%. The incidence of persistent clot without PH is less clear. We evaluated the incidence of persistent perfusion defects in patients followed up after PE and assessed the impact on pulmonary arterial pressure measured by echocardiography. Methods The clinical pathway for outpatient follow-up of patients with PE includes a nuclear medicine ventilationperfusion scan at 5 months post PE. When this is positive, an echocardiogram is requested to look for evidence of PH. A retrospective study of consecutive patients attending outpatient follow-up was carried out to determine the incidence of persistent perfusion defects and echocardiographic findings suggestive of PH. Results Ninety-three patients were identified between February 2009 and July 2011 and their clinical data were studied retrospectively. 59 patients (63%) had persistent perfusion defects at 6 months. Of these 49 (83%) underwent echocardiography of which 12 had undetectable tricuspid regurgitation (TR). In the remaining 37, pulmonary artery systolic pressure (PASP) could be estimated from the TR velocity. Results are shown in Abstract S24 figure 1 and are skewed due to the presence of patients with PH. Median PASP (with IQR) was 32 mm Hg (26e39). The shaded area shows the 95% CIs for the normal PASP (2869.8 mm Hg, mean 6 2SD). Fourteen patients had estimated PASP above the normal range. Six patients were investigated with cardiac catheterisation S24