Purpose The purpose of this paper is to present research work based on the authors’ conceptual framework reported in the VRAP Conference 2013. It is related with an efficient method to obtain an optimal part build orientation for additive manufacturing (AM) by using AM features with associated AM production knowledge and multi-attribute decision-making (MADM). The paper also emphasizes the importance of AM feature and the implied AM knowledge in AM process planning. Design/methodology/approach To solve the orientation problem in AM, two sub-tasks, the generation of a set of alternative orientations and the identification of an optimal one within the generated list, should be accomplished. In this paper, AM feature is defined and associated with AM production knowledge to be used for generating a set of alternative orientations. Key attributes for the decision-making of the orientation problem are then identified and used to represent those generated orientations. Finally, an integrated MADM model is adopted to find out the optimal orientation among the generated alternative orientations. Findings The proposed method to find out an optimal part build orientation for those parts with simple or medium complex geometric shapes is reasonable and efficient. It also has the potential to deal with more complex parts with cellular or porous structures in a short time by using high-performance computers. Research limitations/implications The proposed method is a proof-of-concept. There is a need to investigate AM feature types and the association with related AM production knowledge further so as to suite the context of orientating parts with more complex geometric features. There are also research opportunities for developing more advanced algorithms to recognize AM features and generate alternative orientations and refine alternative orientations. Originality/value AM feature is defined and introduced to the orientation problem in AM for generating the alternative orientations. It is also used as one of the key attributes for decision-making so as to help express production requirements on specific geometric features of a desired part.

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We undertook a randomised, double-blind, placebo-controlled study to compare the analgesic efficacy of pre-operative stellate ganglion block on postoperative pain relief after upper limb orthopaedic surgery. Patients were administered a 3-ml injection during ultrasound-guided stellate ganglion block; 15 patients received lidocaine 2% and 15 patients received 0.9% saline. Following the block, all patients received standardised general anaesthesia. Postoperative analgesia included regular intravenous diclofenac, paracetamol and patient-controlled analgesia with tramadol for 24 h. Patients were observed at 0, 2, 4, 6, 8, 12 and 24 h after surgery for tramadol consumption, cardiovascular variables and visual analogue scale pain scores at rest and on movement. The mean (SD) hourly tramadol consumption was significantly reduced in the lidocaine group compared with the saline group at 4 h (8.0 (10.1) mg vs 28.0 (12.6) mg, respectively; p = 0.001), 6 h (5.3 (10.8) mg vs 17.3 (12.7) mg, respectively; p = 0.013) and 8 h (5.3 (11.8) mg vs 21.3 (9.1) mg, respectively; p = 0.001). The cumulative 24-h tramadol consumption was 97.3 (16.6) mg in the lidocaine group and 150.6 (26.0) mg in the saline group (p = 0.001). There were significant differences in the pain visual analogue scale at rest at two time points; at 4 h the median (IQR [range]) visual analogue scale scores were 4 (4-6 [2-8]) in the lidocaine group and 5 (4-6 [2-7]) in the saline group (p = 0.03), and at 6 h visual analogue scale scores were 3 (3-4 [3-6]) and 4 (4-6 [2-7]), respectively (p = 0.04). Pain visual analogue scale on movement was lower in the lidocaine group at all time intervals compared with the saline group, but this did not reach statistical significance. The present study has demonstrated a postoperative tramadol-sparing and analgesic effect of pre-operative stellate ganglion block in patients undergoing upper limb orthopaedic surgery under general anaesthesia.

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