title: Transcutaneous carbon dioxide levels and oxygen saturation following caesarean section performed under spinal anaesthesia with intrathecal opioids.
abstract: BACKGROUND
  Intrathecal opioids can be associated with respiratory depression which may have serious consequences. We describe the use of a non-invasive monitor (TOSCA) to measure transcutaneous carbon dioxide levels and percentage of haemoglobin oxygen saturation in post-caesarean section patients in two hospitals which used different intrathecal opioids.
  
  
  METHODS
  Eighty-nine women undergoing caesarean section were monitored postoperatively until 08.00h on the first postoperative day. In addition to hyperbaric bupivacaine, patients from Hospital 1 received intrathecal diamorphine 300μg: those from Hospital 2 received intrathecal fentanyl 15μg and postoperative intramuscular morphine 10mg and were given morphine patient-controlled analgesia. Data from TOSCA were analysed the following day. Respiratory depression was defined as oxygen saturations <90% or transcutaneous carbon dioxide levels >7kPa for >2min or the need for medical intervention for clinical respiratory depression.
  
  
  RESULTS
  Sustained hypercapnia was recorded in 8/45 (17.8%) patients from Hospital 1 and 3/44 (6.8%) from Hospital 2. Sustained oxygen saturations <90% were recorded in one patient from Hospital 2 and none from Hospital 1. The overall incidence of respiratory depression was 17.8% in Hospital 1 and 9.1% in Hospital 2. The median duration of hypercapnia was 9min [IQR 5.8-12.4] in Hospital 1 and 11.5min [IQR 7-32.8] in Hospital 2. No patient required medical intervention.
  
  
  CONCLUSIONS
  The incidence of opioid-induced respiratory depression detected by TOSCA is higher than previously reported by other monitoring methods. TOSCA may have a role in detecting subclinical respiratory depression in the obstetric population. Further studies with a control population are needed.
authors.affiliation: Department of Anaesthesia, Gartnavel General Hospital, Glasgow, UK. stephan.dalchow@lanarkshire.scot.nhs.uk
authors.forename: S
authors.initials: S
authors.lastname: Dalchow
authors.forename: O
authors.initials: O
authors.lastname: Lubeigt
authors.forename: G
authors.initials: G
authors.lastname: Peters
authors.forename: A
authors.initials: A
authors.lastname: Harvey
authors.forename: T
authors.initials: T
authors.lastname: Duggan
authors.forename: A
authors.initials: A
authors.lastname: Binning
mesh_terms: D000328:Adult; D000701:Analgesics, Opioid; D000773:Anesthesia, Obstetrical; D000775:Anesthesia, Spinal; D000779:Anesthetics, Local; D002045:Bupivacaine; D002245:Carbon Dioxide / Q000097:blood*; D002585:Cesarean Section; D015331:Cohort Studies; D005260:Female; D006801:Humans; D007278:Injections, Spinal; D016343:Monitoring, Intraoperative; D010100:Oxygen / Q000097:blood*; D010147:Pain Measurement; D010149:Postoperative Pain / Q000188:drug therapy / Q000453:epidemiology / Q000523:psychology; D011247:Pregnancy; D012131:Respiratory Insufficiency / Q000503:physiopathology
chemical_list: D000701:Analgesics, Opioid; D000779:Anesthetics, Local; D002245:Carbon Dioxide; D010100:Oxygen; D002045:Bupivacaine