van Leeuwen 1990.
| Methods | Study design: randomized parallel groups Study dates: not stated |
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| Participants | Country: the Netherlands Sex: both Age: aged 15 to 72 years ASA: I and II Procedure: orthopaedic or ophthalmic operations Study size: 30 |
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| Interventions |
Randomized portion of anaesthetic: parts of TIVA: hypnotic (propofol) infusions MCI: maintenance Intervention 1: maintenance propofol 2 mg/kg/h, N = 10 Intervention 2: maintenance propofol 3 mg/kg/h, N = 10 Intervention 3: maintenance propofol 4 mg/kg/h, N = 10 |
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| Outcomes | Primary outcomes: cardiovascular parameters between groups; duration of anaesthesia, mean total doses (induction and maintenance) of both propofol and alfentanil Secondary outcome: awareness/wakefulness as defined using an awareness classification system (see Table 1): class 1 Quote: "Awareness did not occur in any patient" |
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| Notes |
Non‐randomized portion of anaesthetic: N2O no parts of TIVA hypnotic (propofol) infusions MCI/narcotics infusion (alfentanil): maintenance/muscle relaxants induction yes/maintenance no All patients received premedication with diazepam 10 mg orally 1 to 1.5 h before surgery. Anaesthesia induction: propofol 2 mg/kg + alfentanil 10 µg/kg/min + vecuronium bromide 0.1 mg/kg. A single dose of vecuronium 0.1 mg/kg was used as the muscle relaxant; anaesthesia maintenance: alfentanil infusion 1 µg/kg/min + propofol 20 mg/kg and alfentanil 1 mg was administered as needed. Oxygen in air (FIO2 0.35). Neuromuscular block was reversed with atropine + neostigmine + naloxone 0.2 mg to 0.4 mg, if respiratory depression was present Time of outcome determination: day and month after operation Method of outcome determination: interview Email survey sent to author, no response received |
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| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | Unclear risk | Quote: "The patients were randomly allocated into three groups of ten patients each, Groups A, B, and C. All..." |
| Allocation concealment (selection bias) | Unclear risk | Comment: no information provided |
| Blinding of participants and personnel (performance bias) All outcomes | Unclear risk | Comment: anaesthesiologist: no information provided Comment: different infusion rates difficult to blind to anaesthesiologist (ROB survey van der Maaten 1996) |
| Blinding of outcome assessment (detection bias) All outcomes | Unclear risk | Quote: "The patients were questioned by the anaesthetist about intraoperative awareness. This was done in the recovery room, the day after and one month after the operation" |
| Incomplete outcome data (attrition bias) All outcomes | Low risk | Comment: no missing outcome data |
| Selective reporting (reporting bias) | Low risk | Comment: awareness outcome part of inclusion criteria |
| Other bias | Unclear risk | Comment: insufficient information provided |