The introduction of airbags has not significantly reduced serious thoracic injury for belted occupants in frontal crashes. This thesis has investigated the effectiveness of airbags and the characteristics of residual thoracic organ injury incurred by belted occupants in vehicles equipped with airbags. This study was based on the injury outcome of over 28,000 belted front seat occupants involved in frontal collisions. Data for this analysis was extracted from National Automotive Sampling System / Crashworthiness Data System (NASS/CDS) case years 1993-2007. The use of odds ratios for comparing the effect of airbags on the occurrence of injury has shown that airbags do not significantly increase protection against head and chest injuries. Overall, the lower extremity and the upper extremity were shown to be adversely affected by airbags. The face was the only body region that was shown to benefit from the combination of seat belts and airbags as compared to seat belts alone. An investigation into the characteristics and distributions associated with thoracic organ injuries showed the heart and great vessels are the only thoracic organs that showed a significant reduction in the rate of injury with the inclusion of airbags. In vehicles with airbags, the thoracic organs are injured more frequently than the ribs. When occupants sustain thoracic organ injury, the delta-V of the crash for vehicles with and without airbags is not significantly different. The odds of serious injury to the lungs and spleen are higher for occupants in vehicles with airbags as compared to those in vehicles without airbags. Rib fracture was found to be a poor predictor of moderate to fatal thoracic organ injury. Only 31-61% of thoracic organ injuries occur with an associated rib fracture. / Master of Science

京都大学 / 0048 / 新制・課程博士 / 博士(医学) / 甲第21620号 / 医博第4426号 / 新制||医||1033(附属図書館) / 京都大学大学院医学研究科医学専攻 / (主査)教授 平井 豊博, 教授 宮本 享, 教授 福田 和彦 / 学位規則第4条第1項該当 / Doctor of Medical Science / Kyoto University / DFAM

Caesarean section is a common major surgical procedure and long-term complications have not been fully investigated. By longitudinal population based register studies, based on National health registers and medical data records, maternal complications after caesarean delivery at subsequent labour (N=7 683), among extremely preterm births (N=406), and at remote gynaecologic surgery (N=25 354) were explored. In Paper I, uterine closure was investigated in respect to uterine rupture in a subsequent delivery after caesarean section. Uterine rupture occurred in 1.3 % of women with a previous caesarean section. There was no increased risk of uterine rupture with single compared with double layers for closure of the uterus (adjusted Odds Ratio 1.17, 95 % CI 0.78-1.70). Modifiable risk factors of uterine rupture in a trial of labour after caesarean section included induction of labour and use of epidural analgesia. In Paper II, maternal outcomes and surgical aspects of caesarean section in the extremely preterm period were assessed. Maternal complications were more frequently reported in extremely preterm- compared with term caesarean delivery. No increase in short-term morbidity was observed at 22-24 compared with 25-27 gestational weeks, but uterine corporal incisions were performed more frequently (18.1 % vs. 9.6 %, p=0.02). Furthermore, risk factors for abdominal adhesions after caesarean section and organ injury in remote gynaecologic surgery were analysed (Paper III and IV). Numbers of prior caesarean sections were the most important factor for formation of adhesions. Advanced maternal age, obesity, infection and delivery year 1997-2013 were factors associated with adhesions in conjunction with caesarean section. Organ injury occurred in 2.2 % of women undergoing benign hysterectomy. A history of caesarean section increased the risk (adjusted Odds Ratio 1.74, 95 % CI 1.41-2.15), but was only partly explained by the presence of adhesions. The organ affected depended on medical history; prior caesarean predisposed for bladder injury, prior bowel/pelvic surgery for bowel injury and endometriosis was associated with ureter injury at time of hysterectomy. In conclusion; data from National health registers indicates that caesarean delivery is associated with long-term complications, although the absolute risk of severe complications for the woman is low.