{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,22]],"date-time":"2026-10-22T16:21:18Z","timestamp":1792686078611,"version":"4.5.0"},"reference-count":35,"publisher":"BMJ","issue":"11","license":[{"start":{"date-parts":[[2022,11,15]],"date-time":"2022-11-15T00:00:00Z","timestamp":1668470400000},"content-version":"unspecified","delay-in-days":14,"URL":"http:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/"}],"content-domain":{"domain":["bmj.com"],"crossmark-restriction":true},"short-container-title":["BMJ Open"],"accepted":{"date-parts":[[2022,10,30]]},"published-print":{"date-parts":[[2022,11]]},"abstract":"<jats:sec>\n                    <jats:title>Introduction<\/jats:title>\n                    <jats:p>When patients receive patient-controlled intravenous analgesia (PCIA), no basal infusion is always recommended, as the addition of a basal infusion increases the occurrence of postoperative opioid-induced respiratory depression. However, few studies have investigated whether low basal infusions increase the incidence of postoperative hypoxaemia relative to no basal infusion. We intend to conduct a clinical trial to test the hypothesis that PCIA with a low basal infusion does not increase the occurrence of postoperative hypoxaemia relative to PCIA with no basal infusion.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Methods and analysis<\/jats:title>\n                    <jats:p>\n                      This single-centre parallel randomised controlled clinical trial will be conducted with 160 patients undergoing gastrointestinal tumour surgery. The assigned nurse will set analgesic pumps (low or no basal infusion PCIA) according to block-based randomisation sequence. Other investigators and all participants will be blinded to intervention allocation. All patients will be monitored continuously with the ep pod, a wireless wearable device, recording of oxygen saturation (SpO\n                      <jats:sub>2<\/jats:sub>\n                      ) and daily ambulation duration for 48\u2009hours postoperatively. Three follow-up evaluations will be conducted to assess the analgesic effect (Numeric Rating Scale (NRS) pain score) and opioid-related side effects (Overall Benefit of Analgesic Score (OBAS)). The primary outcome will be the area under the curve for hypoxaemia (defined as SpO\n                      <jats:sub>2<\/jats:sub>\n                      &lt;95%) per hour. The secondary outcomes will be the areas under the curve for hypoxaemia defined as SpO\n                      <jats:sub>2<\/jats:sub>\n                      &lt;90% and &lt;85% per hour, hydromorphone consumption, OBASs at 24 and 48\u2009hours postoperatively, NRS scores at 4, 24 and 48\u2009hours postoperatively, and the ambulation time per hour over 48\u2009hours.\n                    <\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Ethics and dissemination<\/jats:title>\n                    <jats:p>The study has been approved by the Xijing Hospital Ethics Committee (KY20212163-F-1). Written informed consent will be obtained from all patients or their authorised surrogates. All data will be managed with confidentiality. Findings will be disseminated at international conferences and in peer-reviewed journals.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Trial registration number<\/jats:title>\n                    <jats:p>ChiCTR2100054317.<\/jats:p>\n                  <\/jats:sec>","DOI":"10.1136\/bmjopen-2022-064581","type":"journal-article","created":{"date-parts":[[2022,11,16]],"date-time":"2022-11-16T10:00:56Z","timestamp":1668592856000},"page":"e064581","update-policy":"https:\/\/doi.org\/10.1136\/crossmarkpolicy","source":"Crossref","is-referenced-by-count":7,"title":["Effects of hydromorphone-based intravenous patient-controlled analgesia with and without a low basal infusion on postoperative hypoxaemia: study protocol for a randomised controlled clinical trial"],"prefix":"10.1136","volume":"12","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-9814-2952","authenticated-orcid":false,"given":"Yumei","family":"Ma","sequence":"first","affiliation":[{"name":"Department of Anesthesiology and Perioperative Medicine, Fourth Military Medical University Xijing Hospital, Xian, Shaanxi, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Zhuomin","family":"Deng","sequence":"additional","affiliation":[{"name":"PMLS Upstream Marketing Department, Mindray Medical International Ltd, Shenzhen, Guangdong, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Xiangying","family":"Feng","sequence":"additional","affiliation":[{"name":"Department of General Surgery, Fourth Military Medical University Xijing Hospital, Xian, Shaanxi, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Jialin","family":"Luo","sequence":"additional","affiliation":[{"name":"Department of General Surgery, Fourth Military Medical University Xijing Hospital, Xian, Shaanxi, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Yang","family":"Meng","sequence":"additional","affiliation":[{"name":"Department of Anesthesiology and Perioperative Medicine, Fourth Military Medical University Xijing Hospital, Xian, Shaanxi, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Jingjing","family":"Lin","sequence":"additional","affiliation":[{"name":"Department of Anesthesiology and Perioperative Medicine, Fourth Military Medical University Xijing Hospital, Xian, Shaanxi, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Xiaoxiao","family":"Mu","sequence":"additional","affiliation":[{"name":"Department of Anesthesiology and Perioperative Medicine, Fourth Military Medical University Xijing Hospital, Xian, Shaanxi, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Xuan","family":"Yang","sequence":"additional","affiliation":[{"name":"Department of Anesthesiology and Perioperative Medicine, Fourth Military Medical University Xijing Hospital, Xian, Shaanxi, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Huang","family":"Nie","sequence":"additional","affiliation":[{"name":"Department of Anesthesiology and Perioperative Medicine, Fourth Military Medical University Xijing Hospital, Xian, Shaanxi, China"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"239","published-online":{"date-parts":[[2022,11,16]]},"reference":[{"key":"2025121512304785000_12.11.e064581.1","doi-asserted-by":"publisher","DOI":"10.1093\/bja\/aen300"},{"key":"2025121512304785000_12.11.e064581.2","doi-asserted-by":"publisher","DOI":"10.1097\/ALN.0000000000000564"},{"key":"2025121512304785000_12.11.e064581.3","doi-asserted-by":"publisher","DOI":"10.1016\/j.jclinane.2005.01.006"},{"key":"2025121512304785000_12.11.e064581.4","doi-asserted-by":"publisher","DOI":"10.1093\/bja\/87.1.1"},{"key":"2025121512304785000_12.11.e064581.5","doi-asserted-by":"publisher","DOI":"10.1016\/0304-3959(93)90016-I"},{"key":"2025121512304785000_12.11.e064581.6","doi-asserted-by":"publisher","DOI":"10.1016\/S0885-3924(97)00182-6"},{"key":"2025121512304785000_12.11.e064581.7","doi-asserted-by":"crossref","first-page":"795","DOI":"10.1034\/j.1399-6576.2001.045007795.x","article-title":"Efficacy and safety of patient-controlled opioid analgesia for acute postoperative pain. 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