Fehr 2001.
| Methods | Study design: randomized, double‐blind, placebo‐controlled Study dates: not stated |
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| Participants | Country: Switzerland Sex: male and female Age: 18 to 70 ASA: I‐II Procedure: superficial surgical procedures expected to last at least 45 min Study size: 50 |
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| Interventions |
Randomized portion of anaesthetic: cardiac drug vs placebo Intervention 1: maintenance: clonidine 4 µg/kg, N = 25 Intervention 2: maintenance: placebo in 0.9% NaCl 100 mL, N = 25 |
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| Outcomes | Primary outcomes: clonidine's impact on depth of anaesthesia as measured by BIS, BIS guided propofol concentration; implicit memory word test Secondary: awareness/wakefulness as defined using an awareness classification system (see Table 1): class 1 Quote: "No patient had any free recall either of the presented items or of any other pre‐ or intra‐operative events." Comment: no evidence of explicit or implicit memory |
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| Notes |
Non‐randomized portion of anaesthetic: parts of TIVA N2O no/hypnotic (propofol TCI) infusions MCI/narcotics infusion (remifentanil MCI): muscle relaxants maintenance yes induction/maintenance unclear/ADM BIS recorded Induction: propofol (TCI pump target plasma concentration incremental steps until patient unconscious) + rocuronium 0.6 mg/kg + 40% oxygen Maintenance: propofol (target concentration) + remifentanil MCI between 0.01 µg to 1 µg/kg/min maintain BIS and haemodynamic stability Notes: atropine 0.5 mg was administered if the heart rate fell below 40 beats per min Survey was sent to Donat Spahn, corresponding author, on 14 January 2011. No response |
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| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | Unclear risk | Quote: "...we allocated the patients randomly..." |
| Allocation concealment (selection bias) | Unclear risk | Comment: see above quote |
| Blinding of participants and personnel (performance bias) All outcomes | Low risk | Comment: anaesthesiologist: no information provided. However, clonidine or placebo was infused after a steady state was reached post intubation; the use of placebo is a form of blinding |
| Blinding of outcome assessment (detection bias) All outcomes | Unclear risk | Comment: assessor: no information provided |
| 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 |