Study designBMJ 2009; 339 doi: https://doi.org/10.1136/bmj.b5263 (Published 10 December 2009) Cite this as: BMJ 2009;339:b5263
- Philip Sedgwick, senior lecturer in medical statistics
- 1Centre for Medical and Healthcare Education, St George’s, University of London, Tooting, London SW17 0RE
Researchers used a randomised, crossover, single blind, controlled trial to investigate whether local warming of the lower arm and hand facilitated peripheral venous cannulation for patients with leukaemia who required chemotherapy.1 The hand and lower forearm of participants was covered with a carbon fibre heating mitt for 10 minutes. Local warming (mitt warmed to 52°C) was compared with passive insulation (mitt used but heater not switched on). A nurse anaesthetist then inserted a cannula and recorded whether insertion was a success, plus the time taken. Each patient attended two visits at least one week apart.
Which of the following statements, if any, are true?
a) All patients experienced both local warming and passive insulation
b) Patients were not aware whether they received local warming or passive insulation
c) The nurse anaesthetist was not aware whether the patients received local warming or passive insulation